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Biomedical subjects

J Hebert

Publications and source records attributed to J Hebert.

At least 19 recordsLinked to original sources
PubMed2001

Genetic variation in the human urea transporter-2 is associated with variation in blood pressure.

The kidney, by regulating the volume of fluid in the body, plays a key role in regulating blood pressure (BP). The kidney uses primarily sodium and, to a lesser extent, urea to maintain the appropriate volume of fluid. Genetic variation in proteins that determine sodium reabsorption and excretion is known to significantly influence BP. However, the influence of genetic variation in urea transporters on BP has not been examined. We determined therefore whether nucleotide variation in the kidney-specific human urea transporter, HUT2, is associated with variation in BP. After determining the genomic structure of the coding sequence, seven single nucleotide polymorphisms (SNPs) were identified. Two of the SNPs result in Val/Ile and Ala/Thr amino acid substitutions at positions 227 and 357 in the HUT2 open reading frame, respectively. Another SNP is silent and four others are in introns or the 3' untranslated region. Over 1000 hypertensive and low-normotensive individuals of Chinese origin were typed for five of these SNPs using a high-throughput genotyping method. The Ile227 and Ala357 alleles were associated with low diastolic BP in men but not women, with odds ratios 2.1 [95% confidence interval (CI) 1.5-2.7, P < 0.001] and 1.5 (95% CI 1.2-1.8, P < 0.001), respectively. There was a similar trend for systolic BP, and odds ratios for the Ile227 and Ala357 alleles were 1.7 (95% CI 1.2-2.3, P = 0.002) and 1.3 (95% CI 1.1-1.6, P = 0.007), respectively, in men.

Blood Pressure↗
PubMed2001

Streptococcus intermedius, Streptococcus constellatus, and Streptococcus anginosus ("Streptococcus milleri group") are of different clinical importance and are not equally associated with abscess.

Difficulties in distinguishing organisms of the "Streptococcus milleri group" (SMG; Streptococcus intermedius, Streptococcus constellatus, and Streptococcus anginosus), have caused ambiguity in determining their pathogenic potential. We reviewed 118 cases in which SMG isolates had been identified using 16S rDNA sequence. S. constellatus and S. anginosus were isolated far more frequently than was S. intermedius. Nearly all isolates of S. intermedius and most isolates of S. constellatus, but only 19% of those of S. anginosus, were associated with abscess. Our findings suggest that speciation of the SMG may guide diagnostic evaluation, give insight into the possible role of coinfecting organisms, and help assess the need to search for occult abscess.

Abscess↗
PubMed2001

The glycine allele of a glycine/arginine polymorphism in the beta2-adrenergic receptor gene is associated with essential hypertension in a population of Chinese origin.

BACKGROUND: Several studies implicate polymorphisms in the human beta-adrenergic receptor gene (ADRB2) in the susceptibility to hypertension. We sought to replicate these results in a population of Chinese origin primarily from Taiwan and the San Francisco Bay area. METHODS: We genotyped >800 hypertensive subjects and individuals with low-normal blood pressure that were derived largely from the same families as the hypertensive patients for three polymorphisms in the ADRB2 gene: a C/T transition at position 47 (C-47T) in the 5' leader cistron; another C/T transition that results in a glycine/ arginine substitution at codon 16 (Gly16Arg), and a G/C transversion that causes a glutamate/glutamine substitution at codon 27 (Glu27Gln). RESULTS: The Gly16Arg was significantly associated with hypertension (P < .03). Under a dominant model, for hypertension the relative risk for the Gly/Gly and Gly/Arg genotypes versus the Arg/Arg genotype was 1.35 (95% confidence limits [CL] 1.08, 1.70); for low-normal blood pressure the relative risk was 0.79 (95% CL 0.66, 0.94). This polymorphism explained approximately 1% of the variance in systolic and diastolic blood pressures in our study population. There was no evidence of association between the C-47T and Glu27Gln polymorphisms and hypertension in this population. CONCLUSIONS: The Glyl6 allele in the beta2-adrenergic receptor gene is a susceptibility allele for essential hypertension in a population of Chinese origin.

Arginine↗
PubMed2001

High-throughput genotyping with single nucleotide polymorphisms.

To make large-scale association studies a reality, automated high-throughput methods for genotyping with single-nucleotide polymorphisms (SNPs) are needed. We describe PCR conditions that permit the use of the TaqMan or 5' nuclease allelic discrimination assay for typing large numbers of individuals with any SNP and computational methods that allow genotypes to be assigned automatically. To demonstrate the utility of these methods, we typed >1600 individuals for a G-to-T transversion that results in a glutamate-to-aspartate substitution at position 298 in the endothelial nitric oxide synthase gene, and a G/C polymorphism (newly identified in our laboratory) in intron 8 of the 11-beta hydroxylase gene. The genotyping method is accurate-we estimate an error rate of fewer than 1 in 2000 genotypes, rapid-with five 96-well PCR machines, one fluorescent reader, and no automated pipetting, over one thousand genotypes can be generated by one person in one day, and flexible-a new SNP can be tested for association in less than one week. Indeed, large-scale genotyping has been accomplished for 23 other SNPs in 13 different genes using this method. In addition, we identified three "pseudo-SNPs" (WIAF1161, WIAF2566, and WIAF335) that are probably a result of duplication.

Alleles↗
PubMed2000

Preliminary results of chemoradiation as a primary treatment for vulvar carcinoma.

PURPOSE: To assess the role of chemoradiation as a primary treatment for vulvar carcinoma. METHODS AND MATERIALS: Between December 1989 and August 1997, there were 14 patients with the diagnosis of squamous cell carcinoma of the vulva. Two patients were excluded from this study because of advanced stage at presentation. Key information about the remaining 12 patients was extracted from their charts. All patients had biopsy prior to treatment, and were treated with chemoradiation. Radiation was administered to the vulva only. Surgical biopsies from the vulva and inguinal nodal dissection were done 4-6 weeks after radiation treatment. All patients were followed for evaluation of response and clinical detection of recurrence. The period of follow-up ranged from 8 to 125 months. Mean follow-up period was 41 months. RESULTS: All 12 patients showed complete response to the treatment. Only 1 patient (8.3%) developed local recurrence at 3 months posttreatment. Another patient (8.3%) developed nodal recurrence at 30 months posttreatment. Both patients were salvaged by surgical treatment and remained disease free. The actuarial 5-year disease-free survival was 43%. The actuarial 3-year disease-free survival was 84%. The majority of patients developed mild-to-moderate complications due to chemoradiation. These were well tolerated and responded to medical treatment. None of the patients developed late complications to chemoradiation treatment. CONCLUSIONS: Chemoradiation is an effective primary treatment for vulvar carcinoma as shown by these successfully managed cases.

Aged↗
PubMed2000

Lack of evidence for an association between alpha-adducin and blood pressure regulation in Asian populations.

Recent studies have found the tryptophan allele of a glycine to tryptophan polymorphism at position 460 (G460W) of the alpha-adducin protein to be associated with essential hypertension in European populations. We examined whether the tryptophan allele is associated with hypertension in a different population, comprised of subjects of Chinese origin from Taiwan, and Chinese and Japanese origin from the San Francisco Bay area and Hawaii. We adapted the 5' allelic discrimination assay or TaqMan to type individuals for the G460W polymorphism, and using this method we typed more than 1000 individuals. The frequency of the W allele was slightly increased in the treated subjects in the Chinese population (0.458 v 0.423) but not the Japanese population (0.549 v 0.558). We considered dominant, recessive, and additive models in our analysis. There was a significant result for a recessive model for systolic blood pressure in the Chinese population (chi2 6.84, df = 2, P < .05), but only suggestive evidence for diastolic blood pressure (chi2 3.30). In contrast, in the Japanese population, there was no evidence for a positive association under any model. For the combined Chinese and Japanese samples, the evidence for association with alpha-adducin was not significant.

Adult↗
PubMed2000

Full-genome scan for linkage in 50 families segregating the bipolar affective disease phenotype.

A genome scan of approximately 12-cM initial resolution was done on 50 of a set of 51 carefully ascertained unilineal multiplex families segregating the bipolar affective disorder phenotype. In addition to standard multipoint linkage analysis methods, a simultaneous-search algorithm was applied in an attempt to surmount the problem of genetic heterogeneity. The results revealed no linkage across the genome. The results exclude monogenic models and make it unlikely that two genes account for the disease in this sample. These results support the conclusion that at least several hundred kindreds will be required in order to establish linkage of susceptibility loci to bipolar disorder in heterogeneous populations.

Bipolar Disorder↗
PubMed2000

Comparison of the efficacy and safety of mometasone furoate dry powder inhaler to budesonide Turbuhaler.

Mometasone furoate (MF) administered by dry powder inhaler (DPI) was composed with budesonide (BUD) Turbuhaler in the treatment of moderate persistent asthma. The patients were randomized to one of four treatment groups: MF DPI (100, 200, 400 microg b.i.d) or BUD Turbuhaler. 400 microg b.i.d in a 12-week, active-controlled, evaluator-blind, multicentre international trial. The primary efficacy variable was the mean change from baseline to endpoint (last treatment visit) in forced expiratory volume in one second (FEV1). Changes in FEV1 showed a statistically significant superiority (p<0.05) of MF DPI 200 and 400 microg b.i.d compared with the BUD Turbuhaler 400 microg b.i.d treatment. Significant superiority (p<0.05) was also seen in scores for several secondary efficacy variables when MF DPI was compared with BUD Turbuhaler treatment. MF DPI 200 microg b.i.d was comparable to MF DPI 400 microg b.i.d in therapeutic benefit. The incidence of oral candidiasis was no more than 3% in any group. All treatments were well tolerated. A total daily dose of 400 microg of mometasone furoate administered by dry powder inhaler provides a well-tolerated treatment for patients with moderate persistent asthma and results in a significantly greater improvement, when compared to a daily dose of 800 microg BUD Turbuhaler in the parameters measured in this study.

Adolescent↗
PubMed1999

A randomized, multicenter trial of weight-adjusted intravenous heparin dose titration and point-of-care coagulation monitoring in hospitalized patients with active thromboembolic disease. Antithrombotic Therapy Consortium Investigators.

BACKGROUND: Therapy with intravenous unfractionated heparin improves clinical outcome in patients with active thromboembolic disease, but achieving and maintaining a therapeutic level of anticoagulation remains a major challenge for clinicians. METHODS: A total of 113 patients requiring heparin for at least 48 hours were randomly assigned at 7 medical centers to either weight-adjusted or non-weight-adjusted dose titration. They were separately assigned to either laboratory-based or point-of-care (bedside) coagulation monitoring. RESULTS: Weight-adjusted heparin dosing yielded a higher mean activated partial thromboplastin time (aPTT) value 6 hours after treatment initiation than non-weight-adjusted dosing (99.9 vs 78.8 seconds; P =.002) and reduced the time required to exceed a minimum threshold (aPTT >45 seconds) of anticoagulation (10.5 vs 8.6 hours; P =.002). Point-of-care coagulation monitoring significantly reduced the time from blood sample acquisition to a heparin infusion adjustment (0.4 vs 1.6 hours; P <.0001) and to reach the therapeutic aPTT range (51 to 80 seconds) (16.1 vs 19.4 hours; P =.24) compared with laboratory monitoring. Although a majority of patients participating in the study surpassed the minimum threshold of anticoagulation within the first 12 hours and reached the target aPTT within 24 hours, maintaining the aPTT within the therapeutic range was relatively uncommon (on average 30% of the overall study period) and did not differ between treatment or monitoring strategies. CONCLUSIONS: Weight-adjusted heparin dosing according to a standardized titration nomogram combined with point-of-care coagulation monitoring using the BMC Coaguchek Plus System represents an effective and widely generalizable strategy for managing patients with thromboembolic disease that fosters the rapid achievement of a desired range of anticoagulation. Additional work is needed, however, to improve on existing patient-specific strategies that can more effectively sustain a therapeutic state of anticoagulation.

Adult↗
PubMed1999

Thrombin generation after the abrupt cessation of intravenous unfractionated heparin among patients with acute coronary syndromes: potential mechanisms for heightened prothrombotic potential.

OBJECTIVES: The purpose of this study was to determine the mechanistic basis for thrombin generation and increased prothrombotic potential after the abrupt cessation of intravenous (i.v.) unfractionated heparin among patients with acute coronary syndromes. BACKGROUND: A "rebound" increase in prothrombotic potential has been observed biochemically and clinically after the abrupt cessation of unfractionated heparin (UFH) among patients with acute coronary syndromes. Although the mechanism is unknown, tissue factor and the extrinsic coagulation cascade, both operative in atherosclerotic vascular disease and arterial thrombosis, are thought to be centrally involved. METHODS: In a single-center, pilot study, 30 patients with either unstable angina or non-ST segment elevation myocardial infarction who had received a continuous i.v. infusion of UFH for 48 h were randomly assigned to: 1) abrupt cessation, 2) i.v. weaning over 12 h or 3) subcutaneous weaning over 12 h. RESULTS: Thrombin generation (prothrombin fragment 1.2) was evident within 1 h of UFH cessation, increased progressively (by nearly two-fold) at 24 h (p = 0.002) and correlated inversely with tissue factor pathway inhibitor concentration (r = -0.61). Thrombin generation was greatest among patients randomized to abrupt cessation (1.6-fold increase at 24 h) and least in those with i.v. weaning. CONCLUSIONS: Thrombin generation after the abrupt cessation of UFH may represent a drug-induced impairment of physiologic vascular thromboresistance in response to locally generated tissue factor. A dosing strategy of abbreviated i.v. weaning attenuates but does not prevent heparin rebound among patients with acute coronary syndromes.

Adult↗
PubMed1999

A genomic screen of autism: evidence for a multilocus etiology.

We have conducted a genome screen of autism, by linkage analysis in an initial set of 90 multiplex sibships, with parents, containing 97 independent affected sib pairs (ASPs), with follow-up in 49 additional multiplex sibships, containing 50 ASPs. In total, 519 markers were genotyped, including 362 for the initial screen, and an additional 157 were genotyped in the follow-up. As a control, we also included in the analysis unaffected sibs, which provided 51 discordant sib pairs (DSPs) for the initial screen and 29 for the follow-up. In the initial phase of the work, we observed increased identity by descent (IBD) in the ASPs (sharing of 51.6%) compared with the DSPs (sharing of 50.8%). The excess sharing in the ASPs could not be attributed to the effect of a small number of loci but, rather, was due to the modest increase in the entire distribution of IBD. These results are most compatible with a model specifying a large number of loci (perhaps >/=15) and are less compatible with models specifying </=10 loci. The largest LOD score obtained in the initial scan was for a marker on chromosome 1p; this region also showed positive sharing in the replication family set, giving a maximum multipoint LOD score of 2.15 for both sets combined. Thus, there may exist a gene of moderate effect in this region. We had only modestly positive or negative linkage evidence in candidate regions identified in other studies. Our results suggest that positional cloning of susceptibility loci by linkage analysis may be a formidable task and that other approaches may be necessary.

Adolescent↗
PubMed1999

Decreased lactic acidosis and anemia after transfusion of o-raffinose cross-linked and polymerized hemoglobin in severe murine malaria.

Severe anemia is a major cause of death in falciparum malaria. Blood transfusion increases survival in humans and in animal models of this disease. Because of logistic constraints and viral contamination of the blood supply, transfusions are frequently not practical in endemic regions. Modified hemoglobin is an effective O2 carrier in hemorrhagic shock. It is free of infectious contamination, may not require refrigeration, and because of its nitric oxide scavenging and small size, may have pharmacologic benefits in malaria. The effects of transfusions of modified hemoglobin in rats with high-grade parasitemia were evaluated. Modified hemoglobin decreased lactic acidosis and corrected anemia as well as transfusions with red blood cells; these findings may correlate with improved survival and suggest a possible proerythropoietic effect. Further study of this novel therapy is warranted.

Acidosis, Lactic↗
PubMed1998

Worksite and family education for dietary change: the Treatwell 5-a-Day program.

The National Cancer Institute's '5-a-Day for Better Health Campaign is examining the efficacy of interventions in increasing the consumption of fruits and vegetables to five or more servings a day. This paper presents the study design, intervention and baseline survey results of the Treatwell 5-a-Day project, a randomized, controlled worksite-based intervention study. Twenty-two community health centers were randomly assigned to either a Minimal Intervention, Worksite Intervention or Worksite Plus Family Intervention. The Worksite Intervention included participation of employee advisory boards, programs aimed at individual behavior change and programs aimed at changes in the worksite environment. The Worksite Plus Family Intervention incorporated family-focused interventions into the worksite program, including a learn-at-home program, family newsletter, family festival and materials mailings. A self-administered survey was conducted prior to randomization (mean response rate: 87%, n = 1359). Twenty-three percent reported consuming five or more servings of fruits and vegetables a day. Consumption of fruits and vegetables was directly associated with level of household support for healthy eating. The Treatwell 5-a-Day intervention model has the potential to enhance existing worksite-based intervention through incorporation of its family focus, especially given the association of household support with individual eating habits.

Adult↗
PubMed1997

Provider training for patient-centered alcohol counseling in a primary care setting.

OBJECTIVE: To assess the impact of a brief training program on primary care providers' skills, attitudes, and knowledge regarding high-risk and problem drinking. DESIGN: Training plus pretesting and posttesting for program efficacy. SETTING: Ambulatory primary care clinic; academic medical center. PARTICIPANTS: Fourteen attending physicians, 12 residents, and 5 nurse practitioners were randomized by clinical team affiliation to a Special Intervention or usual care condition of a larger study. We report the results of the training program for the Special Intervention providers. INTERVENTION: Providers received a 2-hour group training session plus a 10- to 20-minute individual tutorial session 2 to 6 weeks after the group session. The training focused on teaching providers how to perform patient-centered counseling for high-risk and problem drinkers. MAIN OUTCOME MEASURES: Alcohol counseling skills; attitudes regarding preparedness to intervene and perceived importance and usefulness of intervening with high-risk and problem drinkers; and knowledge of the nature, prevalence, and appropriate treatment of alcohol abuse in primary care populations. RESULTS: After training, providers scored significantly higher on measures of counseling skills, preparedness to intervene, perceived usefulness and importance of intervening, and knowledge. CONCLUSION: A group training program plus brief individual feedback can significantly improve primary care providers' counseling skills, attitudes, and knowledge regarding high-risk and problem drinkers.

Alcohol Drinking↗
PubMed1994

Candidate tumor-suppressor genes MTS1 (p16INK4A) and MTS2 (p15INK4B) display frequent homozygous deletions in primary cells from T- but not from B-cell lineage acute lymphoblastic leukemias.

Using a Southern blot approach, deletions of MTS1 (multiple tumor-suppressor gene 1) and MTS2 (multiple tumor-suppressor gene 2) candidate tumor-suppressor genes have been studied in primary neoplastic cells from 55 acute lymphoblastic leukemia (ALL) patients. Homozygous MTS1 deletions were found in 20 of 24 T-ALL cases and in only 2 of 31 B-lineage cases (P < .001). The deletions involved MTS1 and MTS2 in most cases. Homozygous MTS2 deletions were observed in 16 of 24 T-ALL cases and in 1 of 31 B-lineage ALLs (P < .001), all of them displaying homozygous MTS1 deletions. In 5 cases (4 T and 1 B), deletions involved MTS1 but spared the MTS2 gene, showing that one deletion breakpoint was located between the two genes within a 25-kb region. In 1 T-ALL case, an MTS1 gene rearrangement has occurred downstream to exon 2. Possible hemizygous deletions were found in 6 cases, 4 of them of the B-cell lineage. In 7 ALL cases, cells obtained at presentation and at first relapse were studied and identical results were observed in 6 cases. In 1 B-lineage case, a germline pattern was found at presentation and a possible monoallelic MTS1/MTS2 deletion was observed at relapse. The high frequency of MTS1 and MTS2 homozygous deletions in T-ALLs supports the view that inactivation of these genes plays an important role in the pathogenesis of this type of human leukemia.

Adolescent↗
PubMed1994

Synthesis of high specific activity [3H]-9-cis-retinoic acid and its application for identifying retinoids with unusual binding properties.

all-trans-Retinoic acid is known to bind to the retinoic acid receptors (RARs) resulting in an increase in their transcriptional activity. In contrast, recently identified 9-cis-retinoic acid (9-cis-RA), which is an additional endogenous RA isomer, is capable of binding to both RARs and retinoid X receptors (RXRs). These distinct properties have raised questions as to the biological role governed by these two retinoic acid isomers and the set of target genes that they regulate. Herein, we report the synthesis of high specific activity [3H]-9-cis-RA and its application to study the ligand-binding properties of the various retinoid receptor subtypes. We examined the binding properties of RARs and RXRs for a series of synthetic retinoids and compared the ligand-binding properties of these arotinoid analogs with their ability to regulate gene expression via the retinoid receptors in a cotransfection assay. The utilization of the [3H]-9-cis-RA competitive binding assay and the cotransfection assay has made it possible to rapidly identify important structural features of retinoids leading to increased selectivity for either the RAR or RXR receptor subtypes.

Animals↗