Bio

Clinical Focus


  • Hematology, Pediatric
  • Pediatric Hematology-Oncology
  • Hematology/Oncology/Stem Cell Transplant, Pediatric
  • Oncology (Cancer), Pediatric

Administrative Appointments


  • Chair, Stanford University School of Medicine - Pediatrics (1993 - Present)

Professional Education


  • Board Certification: Hematology, American Board of Internal Medicine (1972)
  • Board Certification: Internal Medicine, American Board of Internal Medicine (1972)
  • Residency:Boston Children's Hospital (1976) MA
  • Residency:Boston Children's Hospital (1974) MA
  • Internship:Boston Children's Hospital (1971) MA
  • Medical Education:Duke University Medical Center (1970) NC

Research & Scholarship

Current Research and Scholarly Interests


My research interests extend from hypothesis-driven studies in biochemistry and cell biology to discovery-driven interests in proteomics and systems biology to clinical treatment of acute lymphoblastic leukemia of children.

Our biochemical studies have centered on the identification and characterization of members of the glutathione peroxidase family of antioxidant enzymes that contain an enzymatically active selenocysteine residue within the primary structure of the protein.

Recently we have undertaken proteomic investigations whose aim is to identify differences in protein expression that may be biomarkers of diseases in children for which an unequivocal diagnostic test is unavailable, or there is little insight to the mechanism of the disease. This discovery-driven research is being used to identify proteins in plasma or urine of children with Kawasaki Disease, an inflammatory disorder that is the leading cause of acquired heart disease in the pediatric population. Other proteomic investigations are being performed in the areas of prematurity, neonatal disorders, acute lymphocytic and myelogenous leukemia, juvenile rheumatoid arthritis, and acquired respiratory distress syndromes.

My other clinical interests are found in hematologic and oncologic diseases of children, particularly acute lymphoblastic leukemia. Research is focused on optimization of multi-component chemotherapy and radiation treatment for these children. In addition, research investigations in pediatric palliative care have been initiated.

Teaching

2013-14 Courses


Publications

Journal Articles


  • Postinduction Dexamethasone and Individualized Dosing of Escherichia Coli L-Asparaginase Each Improve Outcome of Children and Adolescents With Newly Diagnosed Acute Lymphoblastic Leukemia: Results From a Randomized Study-Dana-Farber Cancer Institute ALL Consortium Protocol 00-01 JOURNAL OF CLINICAL ONCOLOGY Vrooman, L. M., Stevenson, K. E., Supko, J. G., O'Brien, J., Dahlberg, S. E., Asselin, B. L., Athale, U. H., Clavell, L. A., Kelly, K. M., Kutok, J. L., Laverdiere, C., Lipshultz, S. E., Michon, B., Schorin, M., Relling, M. V., Cohen, H. J., Neuberg, D. S., Sallan, S. E., Silverman, L. B. 2013; 31 (9): 1202-1210

    Abstract

    We assessed the toxicity and efficacy of dexamethasone and a novel dosing method of Escherichia coli L-asparaginase (EC-Asnase) in children and adolescents with newly diagnosed acute lymphoblastic leukemia (ALL).Patients achieving complete remission (CR) on Dana-Farber Cancer Institute ALL Consortium Protocol 00-01 were eligible for random assignment to 1) dexamethasone or prednisone, administered as 5-day pulses, every 3 weeks, and 2) weekly EC-Asnase, administered as a 25,000 IU/m(2) fixed dose (FD) or individualized dose (ID) starting at 12,500-IU/m(2), adjusted every 3 weeks based on nadir serum asparaginase activity (NSAA) determinations.Between 2000 and 2004, 492 evaluable patients (ages 1 to 18 years) enrolled; 473 patients (96%) achieved CR. Four hundred eight patients (86%) participated in the corticosteroid randomization and 384 patients (81%) in the EC-Asnase randomization. With 4.9 years of median follow-up, dexamethasone was associated with superior 5-year event-free survival (EFS; 90% v 81% for prednisone; P = .01) but higher rates of infection (P = .03) and, in older children, higher cumulative incidence of osteonecrosis (P = .02) and fracture (P = .06). ID EC-Asnase had superior 5-year EFS (90% v 82% for FD; P = .04), but did not reduce the frequency of asparaginase-related toxicity. Multivariable analysis identified both dexamethasone and ID EC-Asnase as independent predictors of favorable EFS.There was no overall difference in skeletal toxicity by corticosteroid type; dexamethasone was associated with more infections and, in older children, increased incidence of osteonecrosis and fracture. There was no difference in asparaginase-related toxicity by EC-Asnase dosing method. Dexamethasone and ID EC-Asnase were each associated with superior EFS. Monitoring NSAA during treatment with EC-Asnase may be an effective strategy to improve outcome in pediatric ALL.

    View details for DOI 10.1200/JCO.2012.43.2070

    View details for Web of Science ID 000316187600021

    View details for PubMedID 23358966

  • Point-of-Care Differentiation of Kawasaki Disease from Other Febrile Illnesses JOURNAL OF PEDIATRICS Ling, X. B., Kanegaye, J. T., Ji, J., Peng, S., Sato, Y., Tremoulet, A., Burns, J. C., Cohen, H. J. 2013; 162 (1): 183-U219

    Abstract

    To test whether statistical learning on clinical and laboratory test patterns would lead to an algorithm for Kawasaki disease (KD) diagnosis that could aid clinicians.Demographic, clinical, and laboratory data were prospectively collected for subjects with KD and febrile controls (FCs) using a standardized data collection form.Our multivariate models were trained with a cohort of 276 patients with KD and 243 FCs (who shared some features of KD) and validated with a cohort of 136 patients with KD and 121 FCs using either clinical data, laboratory test results, or their combination. Our KD scoring method stratified the subjects into subgroups with low (FC diagnosis, negative predictive value >95%), intermediate, and high (KD diagnosis, positive predictive value >95%) scores. Combining both clinical and laboratory test results, the algorithm diagnosed 81.2% of all training and 74.3% of all testing of patients with KD in the high score group and 67.5% of all training and 62.8% of all testing FCs in the low score group.Our KD scoring metric and the associated data system with online (http://translationalmedicine.stanford.edu/cgi-bin/KD/kd.pl) and smartphone applications are easily accessible, inexpensive tools to improve the differentiation of most children with KD from FCs with other pediatric illnesses.

    View details for DOI 10.1016/j.jpeds.2012.06.012

    View details for Web of Science ID 000312915900040

    View details for PubMedID 22819274

  • Alterations in Cerebrospinal Fluid Proteins in a Presymptomatic Primary Glioma Model PLOS ONE Whitin, J. C., Jang, T., Merchant, M., Yu, T. T., Lau, K., Recht, B., Cohen, H. J., Recht, L. 2012; 7 (11)

    Abstract

    Understanding the early relationship between brain tumor cells and their environment could lead to more sensitive biomarkers and new therapeutic strategies. We have been using a rodent model of neurocarcinogenesis in which all animals develop brain tumors by six months of age to establish two early landmarks in glioma development: the appearance of a nestin(+) cell at thirty days of age and the appearance of cellular hyperplasia between 60 and 120 days of age. We now report an assessment of the CSF proteome to determine the changes in protein composition that occur during this period.Nestin(+) cell clusters and microtumors were assessed in 63 ethylnitrosourea-exposed rats on 30, 60, and 90 days of age. CSF was obtained from the cisterna magna from 101 exposed and control rats at 30, 60, and 90 days and then analyzed using mass spectrometry. Differentially expressed peaks were isolated and identified.Nestin(+) cells were noted in all ethylnitrosourea-exposed rats assessed pathologically. Small microtumors were noted in 0%, 18%, and 67% of 30-, 60-, and 90-day old rats, respectively (p<0.05, Chi square). False Discovery Rate analysis of peak intensities showed that the number of true discoveries with p<0.05 increased markedly with increasing age. Isolation and identification of highly differentially detected proteins at 90 days of age revealed increases in albumin and a fragment of ?1 macroglobulin and alterations in glutathionylated transthyretin.The presence of increased albumin, fragments of cerebrospinal fluid proteins, and glutathione breakdown in temporal association with the development of cellular hyperplasia, suggests that, similar to many other systemic cancers, inflammation and oxidative stress is playing an important early role in the host's response to brain tumor development and may be involved in affecting the early growth of brain tumor.

    View details for DOI 10.1371/journal.pone.0049724

    View details for Web of Science ID 000311333800047

    View details for PubMedID 23185417

  • Identification of protein marker in vaginal wall tissues of women with stress urinary incontinence by protein chip array JOURNAL OF OBSTETRICS AND GYNAECOLOGY RESEARCH Wen, Y., Whitin, J., Yu, T., Cohen, H., Polan, M. L., Chen, B. 2012; 38 (1): 89-96

    Abstract

    We sought to investigate protein biomarkers for stress urinary incontinence (SUI) in vaginal tissues using surface-enhanced laser desorption/ionization time-of-flight mass spectrometry (SELDI-TOF MS) and examine if this is a reliable methodology to examine proteins in small tissue specimens.? We compared protein expression profile of vaginal tissue from women with SUI and continent controls. A 22.6kDa peak was identified by subsequent weak cation-exchange, reverse-phase fractionation, gel electrophoresis, and trypsin digestion, then analyzed by matrix assisted laser desorption/ionization mass spectrometry (MALDI MS) and MALDI MS-MS. Biomarker identity and expression level were confirmed by Western-blotting and immunohistochemistry.Expression of the 22.6kDa protein, identified as SM-22?, was significantly higher in women with SUI versus controls. A 3×3-mm tissue sample was sufficient for identification. Western-blot/immunohistochemistry confirmed the SELDI-TOS MS findings.SM-22?, a marker for myofibroblasts, was identified as a biomarker of SUI. Differential protein profiling by SELDI-TOF MS is a powerful and reliable tool for urogynecological research as it allows us to study an array of proteins simultaneously using small tissue samples.

    View details for DOI 10.1111/j.1447-0756.2011.01690.x

    View details for Web of Science ID 000298882800014

    View details for PubMedID 22136672

  • URINE PEPTIDOMICS FOR CLINICAL BIOMARKER DISCOVERY ADVANCES IN CLINICAL CHEMISTRY, VOL 51 Ling, X. B., Mellins, E. D., Sylvester, K. G., Cohen, H. J. 2010; 51: 181-213

    Abstract

    Urine-based proteomic profiling is a novel approach that may result in the discovery of noninvasive biomarkers for diagnosing patients with different diseases, with the aim to ultimately improve clinical outcomes. Given new and emerging analytical technologies and data mining algorithms, the urine peptidome has become a rich resource to uncover naturally occurring peptide biomarkers for both systemic and renal diseases. However, significant analytical hurdles remain in sample collection and storage, experimental design, data analysis, and statistical inference. This study summarizes, focusing on our experiences and perspectives, the progress in addressing these challenges to enable high-throughput urine peptidomics-based biomarker discovery.

    View details for DOI 10.1016/S0065-2423(10)51007-2

    View details for Web of Science ID 000281865700007

    View details for PubMedID 20857622

  • Plasma Biomarkers in a Mouse Model of Preterm Labor PEDIATRIC RESEARCH Yang, Q., Whitin, J. C., Ling, X. B., Nayak, N. R., Cohen, H. J., Jin, J., Schilling, J., Yu, T. T., Madan, A. 2009; 66 (1): 11-16

    Abstract

    Preterm labor (PTL) is frequently associated with inflammation. We hypothesized that biomarkers during pregnancy can identify pregnancies most at risk for development of PTL. An inflammation-induced mouse model of PTL was used. Surface-enhanced laser desorption/ionization time-of-flight mass spectrometry was used to analyze and compare the plasma protein (PP) profile between CD-1 mice injected intrauterine with either lipopolysaccharide (LPS) or PBS on d 14.5 of gestation. The median differences of normalized PP peaks between the two groups were determined using the Mann-Whitney U test and the false discovery rate. In a second series of experiments, both groups of mice were injected with a lower dose of LPS. A total of 1665 peaks were detected. Thirty peaks were highly differentially expressed (p < 0.0001) between the groups. Two 11 kDa protein peaks were identified by MALDI-TOF/TOF-MS and confirmed to be mouse serum amyloid A (SAA) 1 and 2. Plasma SAA2 levels were increased in LPS-treated animals compared with controls and in LPS-treated animals that delivered preterm vs. those that delivered at term. SAA2 has the potential to be a plasma biomarker that can identify pregnancies at risk for development of PTL.

    View details for Web of Science ID 000267249300004

    View details for PubMedID 19287348

  • FDR made easy in differential feature discovery and correlation analyses BIOINFORMATICS Ling, X. B., Cohen, H., Jin, J., Lau, I., Schilling, J. 2009; 25 (11): 1461-1462

    Abstract

    Rapid progress in technology, particularly in high-throughput biology, allows the analysis of thousands of genes or proteins simultaneously, where the multiple comparison problems occurs. Global false discovery rate (gFDR) analysis statistically controls this error, computing the ratio of the number of false positives over the total number of rejections. Local FDR (lFDR) method can associate the corrected significance measure with each hypothesis testing for its feature-by-feature interpretation. Given the large feature number and sample size in any genomics or proteomics analysis, FDR computation, albeit critical, is both beyond the regular biologists' specialty and computationally expensive, easily exceeding the capacity of desktop computers. To overcome this digital divide, a web portal has been developed that provides bench-side biologists easy access to the server-side computing capabilities to analyze for FDR, differential expressed genes or proteins, and for the correlation between molecular data and clinical measurements.(http://translationalmedicine.stanford.edu/Mass-Conductor/FDR.html).

    View details for DOI 10.1093/bioinformatics/btp176

    View details for Web of Science ID 000266109500030

    View details for PubMedID 19376824

  • Idiopathic neutropenia of childhood is associated with Fas/FasL expression CLINICAL IMMUNOLOGY Nadeau, K. C., Callejas, A., Wong, W. B., Joh, J. W., Cohen, H. J., Jeng, M. R. 2008; 129 (3): 438-447

    Abstract

    Idiopathic neutropenia (IN) in children is characterized by decreased neutrophil counts (<1500/microl), can be acute or chronic (greater than 6 months duration). The pathophysiology is not well understood; therefore, potential mechanisms of pediatric IN were investigated. An increase in Fas transcripts in neutrophils of IN patients compared to age-matched healthy control (HC) neutrophils was observed (p<0.005). Increased expression of Fas protein was found in IN neutrophils, while Fas surface expression on other immune cells was similar. Plasma from acute IN patients had higher protein levels of soluble FasL than chronic IN patients. When HC neutrophils were incubated in plasma from IN patients, greater rates of apoptosis were observed. Biochemical studies suggest the apoptotic factor(s) in plasma is heat-sensitive, non-IgG, and 12-50 kD protein. Addition of anti-sFasL blocking antibodies to patient plasma caused a statistically significant decrease in neutrophil apoptosis. These studies show that the Fas/FasL pathway could be associated with neutrophil apoptosis in childhood IN.

    View details for DOI 10.1016/j.clim.2008.08.006

    View details for Web of Science ID 000261011100007

    View details for PubMedID 18819843

  • Capture of phosphopeptides using alpha-zirconium phosphate nanoplatelets ANALYTICAL CHEMISTRY Xu, S., Whitin, J. C., Yu, T. T., Zhou, H., Sun, D., Sue, H., Zou, H., Cohen, H. J., Zare, R. H. 2008; 80 (14): 5542-5549

    Abstract

    Alpha-zirconium phosphate nanoplatelets (alpha-ZrPN) were studied as a binding agent for phosphopeptides. Nanoplatelets of alpha-zirconium phosphate were incubated overnight with zirconium oxychloride, followed by centrifugation, and washed twice with water followed by an aqueous solution of 80% acetonitrile to form the binding agent. Alpha-ZrPN were able specifically to capture phosphoserine-containing peptides from a tryptic digest of a complex peptide mixture in which its abundance was only 0.05%. Alpha-ZrPN also bound peptides containing phosphothreonine and phosphotyrosine. The limit of detection for phosphopeptides is approximately 2 fmol, based on using matrix-assisted laser desorption/ionization mass spectrometry. Alpha-ZrPN were applied for the analysis of tryptic digests of mouse liver and leukemia cell phosphoproteomes and succeeded in identifying 158 phosphopeptides (209 phosphorylation sites) from 101 phosphoproteins in mouse liver lysate and 78 phosphopeptides (104 phosphorylation sites) from 59 phosphoproteins in leukemia cell extract. For these two tryptic digests, the alpha-ZrPN approach is able to capture more phosphopeptides than that obtained from TiO2 particles or from Fe(3+)-IMAC beads, but each method is able to bind some phosphopeptides that the others do not.

    View details for DOI 10.1021/ac800577z

    View details for Web of Science ID 000257598100036

    View details for PubMedID 18522436

  • A potential biomarker in the cord blood of preterm infants who develop retinopathy of prematurity PEDIATRIC RESEARCH Madan, A., El-Ferzli, G., Carlson, S. M., Whitin, J. C., Schilling, J., Najmi, A., Yu, T. T., Lau, K., Dimmitt, R. A., Cohen, H. J. 2007; 61 (2): 215-221

    Abstract

    Preterm infants are at risk of developing sepsis, necrotizing enterocolitis (NEC), chronic lung disease (CLD), and retinopathy of prematurity (ROP). We used high-throughput mass spectrometry to investigate whether cord blood proteins can be used to predict development of these morbidities. Cord blood plasma from 44 infants with a birth weight of <1500 g was analyzed by surface-enhanced laser desorption/ionization time-of-flight mass spectrometry (SELDI-TOF). Six infants developed ROP >or=stage II, 10 CLD, three sepsis, and one NEC. We detected 814 protein signals representing 330 distinct protein species. Nineteen biomarkers were associated with development of >or=stage II ROP [false-discovery rate (FDR) <5%] and none with CLD. Several proteins with molecular weight (Mr) 15-16 kD and pI 4-5 were detected with increased abundance in infants with ROP, while similar Mr proteins with pI 7-9 were less abundant in these patients. Sodium dodecylsulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and sequence analysis identified these proteins as alpha-, beta-, and gamma-globin chains. Partial deamidation of Asn139 in beta-globin chains was observed only in the pI 4-5 proteins. We conclude that there are several promising biomarkers for the risk of ROP. Deamidation of globin chains is especially promising and may indicate underlying prenatal pathologic mechanisms in ROP. Validation studies will be undertaken to determine their clinical utility.

    View details for DOI 10.1203/pdr.0b013e31802d776d

    View details for Web of Science ID 000243714700016

    View details for PubMedID 17237725

  • Improving feature detection and analysis of surface-enhanced laser desorption/ionization-time of flight mass spectra PROTEOMICS Carlson, S. M., Najmi, A., Whitin, J. C., Cohen, H. J. 2005; 5 (11): 2778-2788

    Abstract

    Discovering valid biological information from surface-enhanced laser desorption/ionization-time of flight mass spectrometry (SELDI-TOF MS) depends on clear experimental design, meticulous sample handling, and sophisticated data processing. Most published literature deals with the biological aspects of these experiments, or with computer-learning algorithms to locate sets of classifying biomarkers. The process of locating and measuring proteins across spectra has received less attention. This process should be tunable between sensitivity and false-discovery, and should guarantee that features are biologically meaningful in that they represent chemical species that can be identified and investigated. Existing feature detection in SELDI-TOF MS is not optimal for acquiring biologically relevant data. Most methods have so many user-defined settings that reproducibility and comparability among studies suffer considerably. To address these issues, we have developed an approach, called simultaneous spectrum analysis (SSA), which (i) locates proteins across spectra, (ii) measures their abundance, (iii) subtracts baseline, (iv) excludes irreproducible measurements, and (v) computes normalization factors for comparing spectra. SSA uses only two key parameters for feature detection and one parameter each for quality thresholds on spectra and peaks. The effectiveness of SSA is demonstrated by identifying proteins differentially expressed in SELDI-TOF spectra from plasma of wild-type and knockout mice for plasma glutathione peroxidase. Comparing analyses by SSA and CiphergenExpress Data Manager 2.1 finds similar results for large signal peaks, but SSA improves the number and quality of differences betweens groups among lower signal peaks. SSA is also less likely to introduce systematic bias when normalizing spectra.

    View details for DOI 10.1002/pmic.200401184

    View details for Web of Science ID 000231036100008

    View details for PubMedID 15986333

  • Hospital staff and family perspectives regarding quality of pediatric palliative care PEDIATRICS Contro, N. A., Larson, J., Scofield, S., Sourkes, B., Cohen, H. J. 2004; 114 (5): 1248-1252

    Abstract

    Development of a pediatric palliative care program was preceded by a needs assessment that included a staff survey and family interviews regarding improving pediatric palliative care.Four hundred forty-six staff members and community physicians responded to a written survey regarding comfort and expertise in delivering end of life care. Sixty-eight family members of 44 deceased children were interviewed regarding treatment, transition to palliative care, and bereavement follow-up contact. Frequencies were generated for responses to the staff survey. Five interviewers reviewed the families' narratives and identified frequently occurring themes.Staff members reported feeling inexperienced in communicating with patients and families about end of life issues, transition to palliative care, and do not resuscitate status. Families reported distress caused by uncaring delivery of bad news and careless remarks made by staff members. Staff members reported feeling inexperienced in symptom and pain management and described occasions when pain could have been better managed. Families believed pain had been managed as well as possible despite observing their children suffer. Fifty-four percent of staff members reported that adequate support was not provided for those who treat dying children. Staff members and family members stated their desire for more support. Staff members who described their most difficult experiences caring for a dying child referenced personal pain and inadequate support most frequently.Albeit from different perspectives, staff members and family members shared common concerns and experiences regarding pediatric palliative care. These experiences emphasize the need for additional systematic study, improved education and support for staff members, and continued development of more effective and compassionate delivery of pediatric palliative care.

    View details for DOI 10.1542/peds.2003-0857-L

    View details for Web of Science ID 000224842700008

    View details for PubMedID 15520103

  • Commentary on "Cancer incidence in adolescents and young adults in the United States, 1992-1997" JOURNAL OF ADOLESCENT HEALTH Cohen, H. J. 2003; 32 (6): 403-404
  • Selenomethionine does not affect PSA secretion independent of its effect on LNCaP cell growth PROSTATE Bhamre, S., Whitin, J. C., Cohen, H. J. 2003; 54 (4): 315-321

    Abstract

    Individuals supplemented with selenium have reduced incidence of prostate cancer. This study determines whether selenomethionine specifically affects the secretion of prostate specific antigen (PSA) in vitro.LNCaP cells were supplemented with selenomethionine for 7 days. PSA secretion was determined by ELISA. Cell proliferation was assessed by enumeration of trypan blue excluding cells. Colony formation was determined in soft agar. Cell cycle distribution was determined by FACS analysis of propidium iodide stained cells.Selenomethionine at > or = 70 microM inhibited LNCaP cell growth and colony formation. 0-100 microM selenomethionine did not affect the secretion of PSA by LNCaP cells in cell culture supernatants when normalized to the number of cells in culture. At supra-nutritional concentrations of selenomethionine, LNCaP cells had longer G(0)/G(1) phase in agreement with the inhibitory effects on cell growth.PSA secretion is not specifically inhibited by concentrations of selenomethionine corresponding to plasma selenium concentrations found in individuals supplemented with chemopreventive concentrations of selenized yeast. These data suggest that changes in serum PSA levels in individual patients during selenium supplementation is not an effect specific for PSA secretion, but rather may be a useful indicator for changes in disease progression in individual patients.

    View details for DOI 10.1002/pros.10184

    View details for Web of Science ID 000181056800009

    View details for PubMedID 12539231

  • Extracellular glutathione peroxidase is secreted basolaterally by human renal proximal tubule cells AMERICAN JOURNAL OF PHYSIOLOGY-RENAL PHYSIOLOGY Whitin, J. C., Bhamre, S., Tham, D. M., Cohen, H. J. 2002; 283 (1): F20-F28

    Abstract

    Extracellular glutathione peroxidase (eGPx) is a secreted selenoenzyme with GPx activity. eGPx protein and activity are found in blood plasma and other extracellular fluids. eGPx in plasma is predominantly derived from the proximal tubules of kidneys in humans. Two types of human proximal tubule cells were cultured on semipermeable polycarbonate membranes to determine whether these cells secrete eGPx in a polarized direction. Immortalized human proximal tubule HK-2 cells and primary human proximal tubule cells formed confluent monolayers when cultured on these membrane inserts in culture dishes, as evidenced by transepithelial resistance. Both cell lines also constituted a barrier to diffusion of a fluoresceinated dextran of 75 kDa, a size similar to eGPx homotetramers. In both cell lines, 6- to 12-fold more 35S-methionine-labeled eGPx was immunoprecipitated from the basolateral media than from the apical media, indicating basolateral secretion of eGPx. eGPx was immunolocalized to the extracellular fluid at the basolateral surface of proximal tubules in human kidney. These data support the conclusion that eGPx is secreted through the basolateral membrane of human kidney proximal tubule cells into the extracellular fluid of the kidney, and from there enters blood plasma.

    View details for DOI 10.1152/ajprenal.00014.2001

    View details for Web of Science ID 000176138800003

    View details for PubMedID 12060583

  • Increased expression of extracellular glutathione peroxidase in mice with dextran sodium sulfate-induced experimental colitis PEDIATRIC RESEARCH Tham, D. M., Whitin, J. C., Cohen, H. J. 2002; 51 (5): 641-646

    Abstract

    Extracellular glutathione peroxidase (E-GPx) is a selenoenzyme that reduces hydrogen peroxide and organic peroxides. All plasma glutathione peroxidase (GPx) activity in humans is attributable to E-GPx. The gastrointestinal (GI) tract also synthesizes and secretes E-GPx into the extracellular milieu. Endogenously generated oxidants have been implicated in inflammatory bowel disease (IBD). We evaluated E-GPx levels in a mouse model of IBD using dextran sodium sulfate (DSS). Histologic lesions of the lower GI tract consisted of multifocal areas of mucosal erosion denuded of epithelial cells, reduction in goblet cells, dilated crypts, crypt collapse, submucosal edema, and transmural distribution of mixed inflammatory infiltrates. On d 7, plasma GPx activity in the DSS group increased by 61% compared with the control group (p < 0.05). Western blot analysis demonstrated a 64% increase in E-GPx protein in the plasma of the DSS group after 7 d of treatment (p < 0.01). As the major source of plasma GPx is the kidney, we determined whether the increase in plasma GPx activity and protein was caused by a change in E-GPx synthesis by the kidney. After 3 and 7 d of DSS treatment, E-GPx mRNA levels, relative to glyceraldehyde-3-phosphate dehydrogenase, increased in the kidney (p < 0.05) without a concomitant increase in cellular GPx mRNA on d 7. These results suggest that the inflammatory injury in the intestine elicits an increase in E-GPx in the plasma that is associated with an increase in E-GPx mRNA in the kidney. This implies that renal production of E-GPx may be sensitive to insults distal to the kidney.

    View details for Web of Science ID 000175171600016

    View details for PubMedID 11978890

  • Developmental stage-specific expression of the alpha and beta subunits of the HIF-1 protein in the mouse and human fetus MOLECULAR GENETICS AND METABOLISM Madan, A., Varma, S., Cohen, H. J. 2002; 75 (3): 244-249

    Abstract

    Erythropoietin (Epo) is a glycoprotein hormone that is the primary regulator of erythropoiesis. Transcription of the Epo gene increases in response to hypoxia or anemia. Epo is synthesized in the liver in fetal life and in the kidney later in gestation. In the mammalian fetus the switch in Epo production from the liver to the kidney occurs in the third trimester. Hypoxia-inducible factor (HIF-1) is a heterodimeric transcription factor consisting of an alpha and beta subunit that binds under hypoxic conditions to an enhancer element in the 3' region of the Epo gene. In order to determine if there is a relationship between expression of HIF-1 alpha and beta subunits with the shift in expression of the Epo gene from the liver to the kidney or with the transitional events occurring at birth we analyzed the expression of these mRNAs in mouse and human fetuses at different stages of gestation. Total RNA was extracted from the brain, heart, kidney, liver, and lungs of mice at P15, P17, and P19 of gestation, from newborn mice at Days 1 and 3, from an adult and an anemic adult mouse as well as from human fetuses at 14-22 weeks of gestation. RNA was analyzed by Northern blot and slot-blot hybridization using appropriate cDNA probes. HIF-1alpha and -beta mRNA were expressed in all tissues tested and at all stages of gestation in the mouse and human fetus. Expression of HIF-1alpha and -beta in the mouse fetus was highest in the brain followed by heart, kidney, lung, and liver. Expression in the fetal and newborn mice was higher versus the adult and expression was higher in the anemic versus the normal adult mouse. In the human fetus a higher expression of HIF-1alpha was noted in the brain followed by heart, kidney, lung, and liver. There was a small trend toward a decrease in expression with advancing gestational age. HIF-1beta was expressed to a similar extent in all human tissues examined. Our studies indicate that expression of HIF-1alpha and -beta subunits was not related to the switch in Epo gene expression from the liver to the kidney. Although expression of HIF-1alpha and -beta did not decrease immediately after birth, it is possible that the HIF-1 protein is involved in the various events that occur during transition after birth.

    View details for DOI 10.1006/mgme.2001.3293

    View details for Web of Science ID 000174740300007

    View details for PubMedID 11914036

  • Family perspectives on the quality of pediatric palliative care ARCHIVES OF PEDIATRICS & ADOLESCENT MEDICINE Contro, N., Larson, J., Scofield, S., Sourkes, B., Cohen, H. 2002; 156 (1): 14-19

    Abstract

    As a prelude to establishing a Pediatric Palliative Care Program, we solicited information from families about their experiences and their suggestions for improving the quality of end-of-life care. Participants were English- and Spanish-speaking family members of deceased pediatric patients who received care at Lucile Salter Packard Children's Hospital, Stanford University Medical Center, Palo Alto, Calif.Sixty-eight family members of 44 deceased children were interviewed regarding treatment, transition to palliative care, and bereavement follow-up. Four clinical social workers and one clinical psychologist reviewed the participants' responses and identified frequently occurring themes.Several areas of unsatisfactory interactions with staff were identified: confusing, inadequate, or uncaring communications regarding treatment or prognosis; preventable oversights in procedures or policies; failure to include or meet the needs of siblings and Spanish-speaking family members; and inconsistent bereavement follow-up. A discrepancy emerged between the high degree of pain described by the families and parents' perceptions that pain had been managed well. Community hospice programs are frequently poorly prepared to serve pediatric patients.There is a need to improve pediatric palliative care. Recurring themes in the family interviews suggest useful issues to consider in the development of a palliative care program.

    View details for Web of Science ID 000173079600005

    View details for PubMedID 11772185

  • Intracellular reduction of selenite into glutathione peroxidase. Evidence for involvement of NADPH and not glutathione as the reductant MOLECULAR AND CELLULAR BIOCHEMISTRY Bhamre, S., Nuzzo, R. L., Whitin, J. C., Olshen, R. A., Cohen, H. J. 2000; 211 (1-2): 9-17

    Abstract

    Selenium (Se) in selenite is present in an oxidized state, and must be reduced for it to be incorporated as selenocysteine into selenoenzymes such as glutathione peroxidase (GPx). In vitro, Se, as in selenite, can be reduced utilizing glutathione (GSH) and glutathione reductase (GRed). We determined the effects of decreasing GSH levels, inhibiting GRed activity, and decreasing cellular NADPH on the selenite-dependent rate of GPx synthesis in cultured cells: PC3, CHO, and the E89 glucose-6-phosphate dehydrogenase (G-6-PD)-deficient cell line. A novel statistical analysis method was developed (using Box Cox transformed regression and a bootstrap method) in order to assess the effects of these manipulations singly and in combinations. Buthionine sulfoximine (BSO) was used to decrease GSH levels, 1,3 bis-(2 chloroethyl)-1 -nitrosourea (BCNU) was used to inhibit GRed activity and methylene blue (MB) was used to decrease cellular NADPH levels. This statistical method evaluates the effects of BSO, BCNU, MB and selenite alone and in combinations on GPx activity. Decreasing the GSH level (< 5% of control) did not have an effect on the selenite-dependent rate of GPx synthesis in PC3 or CHO cells, but did have a small inhibitory effect on the rate of GPx synthesis in E89 cells. Inhibiting GRed activity was also associated with either no effect (CHO, E89) or a small effect (PC3) on GPx activity. In contrast, decreasing NADPH levels in cells treated with MB was associated with a large decrease in the selenite-dependent rate of GPx synthesis to 36, 34 and 25% of control in PC3, CHO, and E89 cells, respectively. The effects of BSO plus BCNU were not synergistic in any of the cell lines. The effects of BSO plus MB were synergistic in G-6-PD-deficient E89 cells, but not in PC3 or CHO cells. We therefore conclude that under normal culture conditions, NADPH, and not glutathione, is the primary reductant of Se in selenite to forms that are eventually incorporated into GPx. For cells with abnormal ability to generate NADPH, lowering the GSH levels had a small effect on selenite-dependent GPx synthesis. GRed activity is not required for the selenite-dependent synthesis of GPx.

    View details for Web of Science ID 000089137800002

    View details for PubMedID 11055542

  • Increase in extracellular glutathione peroxidase in plasma and lungs of mice exposed to hyperoxia PEDIATRIC RESEARCH Kim, K. K., Whitin, J. C., Sukhova, N. M., Cohen, H. J. 1999; 46 (6): 715-721

    Abstract

    Extracellular glutathione peroxidase (E-GPx) is a selenium-dependent enzyme that can reduce hydrogen peroxide and phospholipid hydroperoxides. E-GPx is found in plasma and extracellular fluids such as bronchoalveolar lavage fluid. Because lung is one of the tissues that is capable of synthesizing and secreting E-GPx, the effect of exposure to hyperoxia on E-GPx in plasma and lung were studied in an injury model of hyperoxia exposure in adult mice. Exposure to 100% oxygen for 72 h resulted in an increase of 55% in plasma GPx activity and an increase of 50% in the amount of E-GPx protein in the plasma. Exposure to hyperoxia was also associated with an increase in the amount of E-GPx protein in lungs. The 7-fold increase in the amount of E-GPx protein in lungs was not due to plasma contamination of lungs from mice exposed to hyperoxia. E-GPx in the lung is calculated to account for 10% of lung GPx activity in control mice. However, E-GPx is calculated to account for 45% of lung GPx activity in the lungs of mice exposed to hyperoxia for 72 h. Further studies are needed to determine whether the increase in lung E-GPx is due to changes in translation or stability of E-GPx. The role of E-GPx in protecting the lung from oxidative damage warrants further study.

    View details for Web of Science ID 000083870200013

    View details for PubMedID 10590029

  • Expression of extracellular glutathione peroxidase in human and mouse gastrointestinal tract AMERICAN JOURNAL OF PHYSIOLOGY-GASTROINTESTINAL AND LIVER PHYSIOLOGY Tham, D. M., Whitin, J. C., Kim, K. K., Zhu, S. X., Cohen, H. J. 1998; 275 (6): G1463-G1471

    Abstract

    Extracellular glutathione peroxidase (EGPx) is a glycosylated selenoprotein capable of reducing hydrogen peroxide, organic hydroperoxides, free fatty acid hydroperoxides, and phosphatidylcholine hydroperoxides. We found that human large intestinal explant cultures synthesize EGPx and cellular glutathione peroxidase (CGPx) and secrete EGPx. The level of EGPx mRNA expression relative to alpha-tubulin was similar throughout the mouse gastrointestinal tract. EGPx mRNA transcripts have been localized to mature absorptive epithelial cells in human and mouse large intestine. Western blot analysis of mouse intestinal protein has demonstrated the presence of EGPx protein in the small intestine, cecum, and large intestine, with the highest protein levels found in the cecum. Immunohistochemistry studies of human large intestine and mouse small and large intestine sections demonstrated the presence of EGPx protein within mature absorptive epithelial cells. In human large intestine and mouse small intestine, EGPx protein is also present in the extracellular milieu. These results suggest a role for EGPx in protection of the intestinal tract from peroxidative damage and/or in intercellular metabolism of peroxides.

    View details for Web of Science ID 000077746400031

    View details for PubMedID 9843785

  • Plasma glutathione peroxidase and its relationship to renal proximal tubule function MOLECULAR GENETICS AND METABOLISM Whitin, J. C., Tham, D. M., Bhamre, S., Ornt, D. B., Scandling, J. D., Tune, B. M., Salvatierra, O., Avissar, N., Cohen, H. J. 1998; 65 (3): 238-245

    Abstract

    Selenium-dependent extracellular glutathione peroxidase (E-GPx) is found in plasma and other extracellular fluids. Previous studies have indicated that patients with chronic renal failure on dialysis have low plasma GPx activity. In this study, dialysis patients had approximately 40% of control plasma GPx activity, while anephric individuals had lowest plasma GPx activities ranging from 2 to 22% of control. The residual plasma GPx activity in anephric individuals could be completely precipitated by anti-E-GPx antibodies, indicating that all plasma GPx activity can be attributed to E-GPx in both normal and anephric individuals. Plasma GPx activity rises rapidly following kidney transplantation, often reaching normal values within 10 days. The plasma GPx activity in some transplanted patients rises to levels higher than the normal range, followed by a return to the normal range. Since E-GPx in the kidney is primarily synthesized in the proximal tubules, we investigated whether nephrotoxic agents known to disrupt proximal tubule function also affected plasma GPx activity. The beta-lactam antibiotic cephaloglycin rapidly caused a decrease in plasma GPx activity in rabbits. In addition, the chemotherapeutic agent ifosfamide caused a decrease in plasma GPx activity in pediatric osteosarcoma patients. Fanconi syndrome associated with either ifosfamide therapy or valproic acid therapy also caused a decrease in plasma GPx activity. Thus plasma GPx activity is related to kidney function and is decreased in certain situations where nephrotoxic drugs are administered. Monitoring plasma GPx activity may have predictive value in evaluating the function of transplanted kidneys or in predicting those patients particularly at risk of nephrotoxic injury associated with certain medications.

    View details for Web of Science ID 000077722800008

    View details for PubMedID 9851889

  • Serologic markers to monitor the engraftment, growth, and treatment response of human leukemias in severe combined immunodeficient mice BLOOD Arguello, F., Sterry, J. A., Zhao, Y. Z., Alexander, M. R., Shoemaker, R. H., Cohen, H. J. 1996; 87 (10): 4325-4332

    Abstract

    We have investigated human lactate dehydrogenase (LDH) isoenzymes and human nuclear matrix protein 41/7 (NMP 41/7) as potential serologic markers to monitor the course of human leukemia in severe combined immunodeficient (SCID) mice. Following the transplantation of 10(6) human acute lymphoblastic leukemia (ALL) Nalm-6 cells, human specific LDH isoenzymes were measurable in the serum of SCID mice as early as 7 days after transplantation, although serum total LDH increased in some animals as early as 5 days after transplantation. Human NMP 41/7 was measurable in all animals at day 15 after leukemia cell injection. Serum levels of total LDH, human specific LDH and NMP 41/7 increased progressively over time, reaching total LDH levels as high as 50,000 U/L at day 25 after transplantation. To determine whether the levels of LDH and NMP 41/7 in serum were a reflection of human tumor burden, we studied these serologic markers in SCID mice bearing measurable subcutaneous human neuroblastoma tumors, or compared the serum levels of these markers with the number of human leukemia CD10+ cells in the bone marrow of the SCID mice. The serum levels of total LDH, human specific LDH isoenzymes, and NMP 41/7 correlated well with tumor burden, and they drastically decreased or disappeared from serum after the human leukemia or neuroblastoma cells were selectively killed with a single intravenous (IV) injection of 1 to 3 micrograms diphtheria toxin (DT) (the cellular receptor for DT is present on human cells, but not on mouse cells). Paraplegic mice with central nervous system leukemia completely recovered after DT treatment. We conclude that measurements of serum levels of total LDH, human LDH isoenzymes, and NMP 41/7 are sensitive, quantitative, rapid, and easy to perform serologic methods useful to monitor the engraftment, progression, and treatment response of human leukemia in SCID mice.

    View details for Web of Science ID A1996UK87900035

    View details for PubMedID 8639792

  • 1995 Public policy plenary symposium: ''The Crisis in Clinical Research'' PEDIATRIC RESEARCH Genel, M., Kelly, W. N., Chesney, R. W., Starfield, B., Cohen, H. J., Murray, T. H. 1996; 39 (5): 902-913

    View details for Web of Science ID A1996UG00100027

    View details for PubMedID 8726249

  • EXTRACELLULAR GLUTATHIONE-PEROXIDASE MESSENGER-RNA AND PROTEIN IN HUMAN CELL-LINES ARCHIVES OF BIOCHEMISTRY AND BIOPHYSICS Avissar, N., KERL, E. A., Baker, S. S., Cohen, H. J. 1994; 309 (2): 239-246

    Abstract

    Extracellular glutathione peroxidase (E-GPx) and cellular glutathione peroxidase (C-GPx) are selenoenzymes encoded by two distinct genes. Using specific immunoprecipitations of [75Se]selenium metabolically labeled human cell lines in culture, it was found that Caco-2, Hep3B, Hep G2, and Caki-2 synthesize C-GPx and E-GPx and secrete E-GPx. HBL-100, BT-20, and MCF-7 synthesize only C-GPx. The relationship between Se status (as determined by C-GPx activity) and E-GPx and C-GPx mRNA steady-state levels was investigated in Hep G2, Caco-2, and Caki-2. The most Se-deficient Hep G2, Caco-2, and Caki-2 cells had 8.7 +/- 2.6, 11.2 +/- 4.9, and 9.4 +/- 5.0%, respectively, of C-GPx activity of the replete cells. The steady-state levels of mRNA were measured by Northern and slot blot hybridization analysis. By Northern analysis, a single band was present at 1.0 and 1.80 kb for C-GPx and E-GPx mRNA, respectively, in all three cell lines. Scanning densitometry of the blots revealed that the most Se-deficient cells had 30-50% C-GPx mRNA and 60-80% E-GPx mRNA of the replete cells. It is concluded that, in addition to previously examined human cell lines, Hep3B and Caco-2 make and secrete E-GPx while HBL-100 and BT-20 do not. The slightly reduced levels of G-GPx and E-GPx mRNA in Se-deficient human cell lines can only partially account for the decreased C-GPx activity in Se-deficient human cell lines.

    View details for Web of Science ID A1994MY85800006

    View details for PubMedID 8135533

  • HUMAN KIDNEY PROXIMAL TUBULES ARE THE MAIN SOURCE OF PLASMA GLUTATHIONE-PEROXIDASE AMERICAN JOURNAL OF PHYSIOLOGY Avissar, N., Ornt, D. B., Yagil, Y., Horowitz, S., Watkins, R. H., KERL, E. A., Takahashi, K., Palmer, I. S., Cohen, H. J. 1994; 266 (2): C367-C375

    Abstract

    The sites of synthesis of extracellular (E) glutathione peroxidase (GPX), a unique selenoglycoprotein present in plasma, are not known. To investigate the possibility that the kidney is the main source for the plasma GPX, we examined GPX activities and selenium concentrations in the plasma of patients with renal failure on dialysis and nephrectomized patients before and after kidney transplantation. Plasma GPX activities in these patients were 42, 22, and 180% of normal EGPX activity, respectively, whereas plasma Se levels were within the normal range. Twenty-four hours after nephrectomy of anesthetized rats, plasma GPX activity was 30.0 +/- 6.4% of the activity at zero time. Northern hybridization analysis of eight human tissues probed with EGPX and cellular glutathione peroxidase (CGPX) cDNA revealed that the ratio of EGPX to CGPX was highest in the kidney. cRNA in situ hybridization studies on kidney slices showed that only proximal tubular epithelial cells and parietal epithelial cells of Bowman's capsule contained EGPX transcripts. Caki-2, a proximal tubular renal carcinoma cell line, makes and actively secretes EGPX. Taken together, these results strongly suggest that kidney proximal tubular cells are the main source for GPX activity in the plasma.

    View details for Web of Science ID A1994NA80100006

    View details for PubMedID 8141250

  • COMPARATIVE PHARMACOKINETIC STUDIES OF 3 ASPARAGINASE PREPARATIONS JOURNAL OF CLINICAL ONCOLOGY Asselin, B. L., Whitin, J. C., Coppola, D. J., RUPP, I. P., Sallan, S. E., Cohen, H. J. 1993; 11 (9): 1780-1786

    Abstract

    As part of pharmacologic studies of asparaginase (ASNase), we determined the half-life of ASNase activity and protein, and the effect of dose, repeated doses, different drug preparations, and hypersensitivity reactions on the half-life (t1/2) of serum ASNase activity.We measured ASNase activity (spectrophotometric assay) in serum samples obtained from patients with acute lymphoblastic leukemia (ALL) at various times during their therapy with intramuscular ASNase. ASNase protein was measured by enzyme-linked immunoadsorbent assay (ELISA).Studies following the initial dose of Escherichia coli-derived ASNase demonstrated no difference in apparent t1/2 following 25,000 IU/m2 versus 2,500 IU/m2 (1.24 v 1.35 days, P = .2). The apparent t1/2s following maintenance doses of E coli ASNase (middle dose t1/2, 1.28 days, or last dose t1/2, 1.14 days) showed no difference when compared with the initial dose of ASNase (P = .3 to .9). There was no significant difference between the apparent t1/2s of ASNase activity and ASNase protein (n = 8, P = .2 to .6). The serum t1/2 was 0.65 and 5.73 days for patients receiving Erwinia or polyethylene glycol (PEG)-modified E coli ASNase, respectively, as the induction dose. ASNase activity was undetectable in sera of four patients studied in the week following an anaphylactic reaction to E coli ASNase and the t1/2 was significantly shorter in five patients with a history of allergic reaction to E coli ASNase who were studied following a dose of PEG ASNase, (t1/2, 1.80 days).We conclude that (1) the apparent t1/2 of ASNase is dependent on enzyme preparation used, but is not affected by dose or by repeated use; (2) the apparent t1/2 of E coli ASNase as a protein is the same as the apparent t1/2 of enzymatic activity; and (3) patients who have had a hypersensitivity reaction to E coli ASNase have a decreased apparent t1/2 with both E coli and PEG ASNase.

    View details for Web of Science ID A1993LW36900021

    View details for PubMedID 8355045

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