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B Weber

Publications and source records attributed to B Weber.

At least 145 records · Page 8Linked to original sources
PubMed1998

Reduction of diagnostic window by new fourth-generation human immunodeficiency virus screening assays.

In order to reduce the diagnostic window between the time of human immunodeficiency virus (HIV) infection and laboratory diagnosis, new screening enzyme-linked immunosorbent assays (ELISAs) which permit the simultaneous detection of HIV antigen and antibody have been developed. Two fourth-generation assays, HIV DUO (Biomérieux) and HIV Combi (Boehringer Mannheim), for the combined detection of HIV antigen and antibody, were compared with a third-generation assay (HIV-1/HIV-2 3rd Generation Plus enzyme immunoassay [EIA]; Abbott) and a p24 antigen test (HIV-1 Ag monoclonal; Abbott). A total of 17 seroconversion panels, 15 cell culture supernatants infected with different HIV type 1 (HIV-1) subtypes, and 255 potentially cross-reactive serum samples were tested. Ten seroconversions were detected an average of 8.1 days earlier with HIV DUO and 7.5 days earlier with HIV Combi than with the third-generation ELISA. Overall, in the 17 seroconversion panels tested, HIV DUO detected HIV-1 infection an average of 4.8 days and HIV Combi detected infection an average of 4.4 days earlier than HIV-1/HIV-2 3rd Generation Plus EIA. HIV antigen was detected with HIV DUO and HIV Combi in all of the 15 cell culture supernatants infected with different HIV-1 subtypes, including subtype O. With fourth-generation assays, considerably fewer false-positive results (n = 4 to 6) were obtained, in comparison with the third-generation EIA (n = 18). Fourth-generation assays permit an earlier diagnosis of HIV infection than third-generation antibody screening assays through the detection of p24 antigen, which may be present in serum samples from individuals with recent HIV infection prior to seroconversion.

AIDS Serodiagnosis↗
PubMed1998

Evaluation of the new automated enzymun-test anti-HBc plus for the detection of hepatitis B virus core antibody.

The new automated Enzymun-Test anti-HBc Plus for the detection of antibodies to hepatitis B virus (HBV) core antigen (anti-HBc) after pretreatment with reducing agents dithiothreitol (25 degrees C; + DTT) or potassium bisulfite (37 degrees C; + MBS) was evaluated by testing 571 serum and plasma samples. The panel included dilution series of reference standards and samples from chronic carriers, one seroconversion panel, samples from patients in acute or chronic stage of the disease or resolved hepatitis B, preselected sera from blood donors that were initially reactive in an anti-HBc assay without pretreatment, potentially cross-reactive serum samples obtained from patients suffering from other diseases or with passed infections other than HBV, pregnant women and individuals with HBV vaccination. The IMx CORE(TM) (Abbott Diagnostics) served as reference assay. Discrepant samples were further investigated with two different commercial anti-HBc enzyme immunoassays, other HBV-specific serological markers and HBV DNA hybridization. The sensitivity of the Enzymun-Test Anti-HBc Plus (25 degrees + DTT, and 37 degrees C; + MBS) in comparison to the reference assay was 100%. The IMx CORE showed a twofold higher sensitivity than Enzymun-Test Anti-HBc Plus for anti-HBc detection in dilution series of serum samples from HBV carriers. The agreement in terms of specificity of the Enzymun-Test Anti-HBc Plus (25 degrees C; + DTT, and 37 degrees C; + MBS) and in comparison to IMx CORE was 97.4 and 96.4%, respectively. After resolution of discrepant results (3 samples were tested false negative with IMx CORE), the agreement in terms of specificity of the Enzymun-Test Anti-HBc Plus (25 degrees C; + DTT, and 37 degrees C; + MBS) in comparison to the combination of the comparative assays was 98.3 and 97.4%, respectively. In conclusion, the new automated Enzymun-Test Anti-HBc Plus with sample pretreatment with DTT (25 degrees C; + DTT) or MBS (37 degrees C; + MBS) permits a highly sensitive and specific detection of anti-HBc in diagnostic virology and blood donation testing.

Hepatitis B Antibodies↗
PubMed1998

Quantification of viral load: clinical relevance for human immunodeficiency virus, hepatitis B virus and hepatitis C virus infection.

Quantitative determination of viral load using nucleic acid amplification techniques represents the most accurate prognostic marker for human immunodeficiency virus type 1 (HIV-1) infection, independently of CD4+ cell count. Overall, the different methods for HIV-1 RNA determination (RT-PCR, nucleic acid sequence-based amplification, branched DNA) show a good reproducibility (0.5 log), however for low copy numbers and in HIV-1-infected children the variability may exceed 0.7 log. In non-HIV-1 subtype B infections the copy number is underestimated. While serology permits an accurate follow-up of hepatitis B virus (HBV) infection, HBV DNA quantification is used for monitoring of antiviral therapy, determination of infectiosity and in combination with serological markers for the resolution of unusual profiles, i.e. isolated anti-HBc reactivity. The prognostic relevance of hepatitis C virus (HCV) RNA determination is of limited value for the long-term prognosis of chronic hepatitis C, however the viral load may predict the outcome of antiviral therapy. Genetic diversity represents a challenge for HCV RNA quantification.

Acquired Immunodeficiency Syndrome↗
PubMed1998

Improvement of the specificity of enzyme immunoassays for the detection of rotavirus and adenovirus in fecal specimens.

A variable rate of false-positive results may be observed with commercial enzyme immunoassays (EIAs) for the detection of rotavirus and adenovirus antigen in stool specimens, depending on the quality of the reagents and the presence of potentially interfering substances in stool samples. The present study was performed in an attempt to improve the specificity of current commercial rotavirus and adenovirus EIAs without significant loss of sensitivity by optimizing the cut-off value. A collective of 174 stool samples obtained from children suffering from acute gastroenteritis was tested. Electron microscopy (EM) and PAGE were used as reference methods for rotavirus detection. For the evaluation of the adenovirus kits, virus isolation in cell culture and the polymerase chain reaction served as reference standards. The highest sensitivity for rotavirus and adenovirus detection was achieved by the Ridascreen(R) Rotavirus and Ridascreen Adenovirus. However, the Ridascreen(R) Rotavirus and Ridascreen Adenovirus produced the highest number of false-positive results (n = 9) for each rotavirus and adenovirus detection. Cross-reactivities to coronaviruses and reoviruses were observed with the rotavirus antigen EIAs. For Rotazyme II, Ridascreen Rotavirus and Ridascreen Adenovirus, the specificity could be markedly increased without loss of sensitivity by doubling the cut-off value. For the alternative immunoassays, which were overall more specific, it was not possible to significantly decrease the rate of false-positive results without impairment of sensitivity by raising the cut-off value. In conclusion, at least for some rotavirus and adenovirus antigen EIAs, the cut-off value set by the manufacturer may not permit an optimal differentiation between true-positive and -negative samples. By raising the cut-off value from 50 to 100%, the specificity of two rotavirus antigen and one adenovirus antigen EIA can be improved markedly without significant loss of sensitivity.

Adenoviridae Infections↗
PubMed1998

Human immunodeficiency virus and hepatitis B virus infection in pregnancy: diagnostic potential of viral genome detection.

Hepatitis B virus (HBV) and human immunodeficiency virus (HIV) account for millions of cases of vertical infections worldwide. Laboratory diagnosis is essential for the detection of potentially infectious carriers. HBeAg represents the best serological marker for HBV replication. Since 10% of HBeAg-negative carriers transmit the virus to their children, determination of viral DNA is more reliable for the assessment of the risk to vertical infection. Risk assessment of vertical HIV transmission and monitoring AZT therapy during pregnancy are achieved by determination of HIV-1 viral load and CD4+ cell count. HIV-1 RNA or cDNA detection permits a nearly 100% sensitive diagnosis of congenital HIV infection already 2 weeks after birth. While qualitative HBV DNA determination should be limited only to anti-HBe carriers in order to assess infectiosity, HIV-1 RNA measurement represents in combination with the CD4+ cell count the best prognostic marker for vertical HIV infection and for the follow-up of infected children.

Female↗
PubMed1998

Predictive value of tubular markers for the development of microalbuminuria in adolescents with diabetes.

The predictive value of tubular proteinuria and/or enzyme excretion for the development of microalbuminuria in patients with diabetes mellitus was investigated over a period of 7.5 years in 64 children and adolescents without microalbuminuria at baseline. An abnormal urinary excretion of N-acetyl-beta-D-glucosaminidase (NAG) preceded the increase of albumin excretion in all 8 patients (12.5%) developing microalbuminuria during this period (positive/negative predictive value 0.2 and 1.0, respectively). Also both, the actual as well as the long-term glycemic control (HbAlc) up to the onset of abnormal NAG excretion were predictive for the development of microalbuminuria. Fifty percent of those patients with both an elevated NAG excretion and an HbAlc > or = 9% developed micro-albuminuria within the next 5 years. Therefore, periodic monitoring of urinary NAG excretion should be incorporated into the follow-up of patients with type 1 diabetes mellitus.

Acetylglucosaminidase↗
PubMed1998

Factors modifying the effect of hyperglycemia on the development of retinopathy in adolescents with diabetes. Results of the Berlin Retinopathy Study.

The Berlin Retinopathy Study follows children from the onset of diabetes with serial retinal examinations by fluorescein angiography. It confirmed that long-term poor glycemic control, both before and after puberty, is the major risk factor for the development of retinal changes. The relationship between long-term HbAlc and background retinopathy follows an exponential, non-linear function. Apart from glycemia, several other factors (age at onset, puberty, lipids, blood pressure, genetic factors, smoking) may be of varying relevance in the individual patient. Nevertheless, best glycemic control from the onset of diabetes appears to be of outstanding importance as the HbAlc levels already during the first year of diabetes are related to the later development of background retinopathy.

Adolescent↗
PubMed1998

Mineralocorticoid receptor also modulates basal activity of hypothalamus-pituitary-adrenocortical system in humans.

Hippocampal mineralocorticoid (MRs) and glucocorticoid receptors (GRs) have been demonstrated to regulate the activity of the hypothalamus-pituitary-adrenocortical (HPA) system. To elucidate the role of the hippocampal MR in the circadian activity of the human HPA system, we studied diurnal secretory profiles of corticotropin (ACTH) and cortisol in 10 healthy male humans before and after an 8-day treatment with the MR antagonist spironolactone. 24-hour blood sampling at 30-min intervals was performed for estimation of cortisol (q30) and ACTH (q120). Saliva cortisol was measured for estimation of unbound cortisol. At the end of the 24-hour sampling period a corticotropin-releasing hormone (CRH) challenge was performed. High plasma concentrations of the active metabolite canrenone were achieved (begin of sampling: 2,653 +/- 693 nmol/l; end of sampling: 747 +/- 177 nmol/l). There was a significant increase in the diurnal minima (37.1 +/- 13.3 vs. 23.7 +/- 8.9 nmol/l, p < 0.02) and mean cortisol (193.5 +/- 25.8 vs. 173.0 +/- 23. 0 nmol/l, p < 0.03) plasma concentrations. However, the diurnal peak concentrations and pulsatile secretory features were unchanged after spironolactone treatment. For saliva cortisol, the only significant treatment difference was a decrease in the diurnal amplitude of cortisol relative to the diurnal mean concentration (2.56 +/- 0.47 vs. 3.11 +/- 0.87, p < 0.03). After spironolactone treatment there was a decrease in diurnal mean ACTH concentrations (46.2 +/- 14.4 vs. 41.8 +/- 10.3 pmol/l). There was no difference in the ACTH and cortisol response after infusion of CRH before and after spironolactone treatment. CBG plasma concentrations were significantly increased (22.4 +/- 2.3 vs. 19.2 +/- 2.7 mg/l, p < 0. 01) after spironolactone treatment, which possibly contributed to the observed increase in plasma cortisol. In summary, as predicted from animal studies we found significant effects of MR antagonization to be restricted to time windows of low HPA system activity. These findings are similar to the effects of aging upon the HPA system. However, the effect of spironolactone treatment was small, suggesting that the HPA system activity in humans is modulated but not regulated by the hippocampal MR.

Adrenal Cortex↗
PubMed1998

Sequence analysis of BRCA1 and BRCA2: correlation of mutations with family history and ovarian cancer risk.

PURPOSE: Previous studies of mutations in BRCA1 or BRCA2 have used detection methods that may underestimate the actual frequency of mutations and have analyzed women using heterogeneous criteria for risk of hereditary cancer. PATIENTS AND METHODS: A total of 238 women with breast cancer before age 50 or ovarian cancer at any age and at least one first- or second-degree relative with either diagnosis underwent sequence analysis of BRCA1 followed by analysis of BRCA2 (except for 27 women who declined analysis of BRCA2 after a deleterious mutation was discovered in BRCA1). Results were correlated with personal and family history of malignancy. RESULTS: Deleterious mutations were identified in 94 (39%) women, including 59 of 117 (50%) from families with ovarian cancer and 35 of 121 (29%) from families without ovarian cancer. Mutations were identified in 14 of 70 (20%) women with just one other relative who developed breast cancer before age 50. In women with breast cancer, mutations in BRCA1 and BRCA2 were associated with a 10-fold increased risk of subsequent ovarian carcinoma (P = .005). CONCLUSION: Because mutations in BRCA1 and BRCA2 in women with breast cancer are associated with an increased risk of ovarian cancer, analysis of these genes should be considered for women diagnosed with breast cancer who have a high probability of carrying a mutation according to the statistical model developed with these data.

Adult↗
PubMed1998

Increased diurnal plasma concentrations of dehydroepiandrosterone in depressed patients.

Activation of the hypothalamus-pituitary-adrenocortical system is a biological core symptom of depression. Although the regulation of cortisol secretion is well studied in this condition, there is no information about the diurnal activity of dehydroepiandrosterone (DHEA) secretion. Therefore, we studied 24-h DHEA plasma concentrations (every 30 min) in severely depressed patients (n = 26) and healthy controls (n = 33). We found depression to significantly increase diurnal minimal and mean DHEA plasma concentrations, whereas there was no effect on the diurnal maximal plasma concentration and the diurnal amplitude of DHEA. In particular, we found a parallel increase in mean DHEA (5.8 +/- 3.6 vs. 3.4 +/- 1.9 nmol/L; P < 0.003), cortisol (286 +/- 65 vs. 184 +/- 29 nmol/L; P < 0.0001) and ACTH (7.14 +/- 2.06 vs. 5.72 +/- 1.36 pmol/L; P < 0.002) plasma concentrations. The novel finding of parallel increases in diurnal DHEA and cortisol plasma concentrations in depressed patients has important implications for the regulation of the hypothalamus-pituitary-adrenocortical system in conditions of chronic stress and for the rationale of DHEA treatment in depressed patients.

Adrenocorticotropic Hormone↗
PubMed1998

PET with 18fluorodeoxyglucose and hexamethylpropylene amine oxime SPECT in late whiplash syndrome.

BACKGROUND: Many patients have cognitive abnormalities and psychological problems after whiplash injury to the cervical spine. To our knowledge, neuroradiologic imaging has not depicted brain damage that explains the symptoms. Parietotemporo-occipital perfusion deficits on hexamethylpropylene amine oxime (HMPAO) SPECT studies have been described among patients who have sustained whiplash injury. METHODS: We examined 13 patients with typical late whiplash syndrome (study group) using HMPAO SPECT, 18fluorodeoxyglucose (FDG) PET, and MRI of the brain and compared the findings with those for 16 control subjects who underwent FDG PET. RESULTS: In the study group, statistical parametric mapping revealed significantly decreased FDG uptake in the frontopolar and lateral temporal cortex and in the putamen. The frontopolar hypometabolism correlated significantly with scores of the Beck Depression Inventory. However, in individual cases, reliability in the depiction of hypometabolic areas was relatively low. No alterations were found in the parietotemporo-occipital area. In these areas, decreased uptake of HMPAO and FDG correlated with cortical mass. CONCLUSION: FDG PET did not allow reliable diagnosis of metabolic disturbances for individual patients. Therefore, we do not recommend FDG PET or HMPAO SPECT as a diagnostic tool in routine examinations of patients with late whiplash syndrome.

Adult↗
PubMed1998

Effects of major depression, aging and gender upon calculated diurnal free plasma cortisol concentrations: a re-evaluation study.

Depression, aging and female gender are associated with increased diurnal concentrations of total plasma cortisol. For the physical effects of hypercortisolemia, however, it is generally assumed that free rather than total plasma cortisol concentrations are of importance. Herein, we report a mathematical approach to determine free plasma cortisol concentrations on the basis of total cortisol, corticosteroid binding-globulin (CBG) and albumin plasma concentrations. This approach was used to re-evaluate two sets of data in order to estimate the effect of depression as well as the effect of aging and gender upon free plasma cortisol concentrations. Comparing male depressed patients with healthy controls, we found 24-hour free cortisol minima (MIN: 4.1 +/- 1.8 vs. 1.6 +/- 1.1 nmol/l, p < 0.0001), mean (MEAN: 25.5 +/- 6.7 vs. 10.4 +/- 2.7 nmol/l, p < 0.0001) and maximal (MAX: 85.3 +/- 23.3 vs. 45.2 +/- 15. 8 nmol/l, p < 0.0001) concentrations to be significantly increased in depressed patients. In general, the impact of depression upon total plasma cortisol were not only maintained, but stronger regarding free plasma cortisol. Also, age was associated with free plasma cortisol MIN (F1,30= 10.8, p < 0.003) and free plasma cortisol MEAN (F1,30 = 8.9, p < 0.006). All effects of age upon total plasma cortisol were generally also found in free plasma cortisol, though with less impact. No effect of gender upon any of the given free plasma cortisol outcome variables was found. Taken together, our re-evaluation clearly shows not only depression but also aging to be associated with increases in free plasma cortisol concentrations. This finding is in line with the observation that in both conditions medical problems triggered and/or maintained by glucocorticoids (e.g. osteoporosis) are frequently seen.

Adult↗
PubMed1998

Effect of neuromuscular blockers and opiates on the cerebrovascular response to endotracheal suctioning in adults with severe head injuries.

BACKGROUND: Intracranial hypertension occurs in response to routine procedures such as endotracheal suctioning in patients with severe head injuries. In some patients, the intracranial pressure does not immediately return to baseline levels. OBJECTIVES: To examine the effect of drug administration on cerebrovascular response to endotracheal suctioning in adults with severe head injuries. METHODS: Seventy-one subjects were divided into 3 groups: those who received no drugs, those treated with opiates only (morphine sulfate and fentanyl citrate), and those treated with a neuromuscular blocking agent (vecuronium bromide) plus opiates. A controlled protocol involving 2 sequences of endotracheal suctioning that included hyperoxygenation, hyperinflation, and suctioning was used for all subjects. Two-way repeated-measures analyses of variance were done with type of drug as the between-subject factor and phase of suctioning as the within-subject factor. Survival analysis was used to compare the return of intracranial pressure to baseline levels among the 3 groups. RESULTS: Changes in intracranial pressure were significantly smaller in subjects who received a neuromuscular blocking agent plus opiates than in subjects who did not receive any drugs or received opiates only. The greatest increase in intracranial pressure from baseline was in the first and second phases of suctioning. The 3 groups showed no significant difference in the return of intracranial pressure to baseline level. CONCLUSIONS: Neuromuscular blockers attenuate the increases in intracranial pressure that occur with endotracheal suctioning. It is not known whether control of procedurally induced elevations in intracranial pressure affects long-term outcomes in adults with severe head injuries.

APACHE↗
PubMed1998

Youth suicide prevention: a survey and analysis of policies and efforts in the 50 states.

State-level initiatives directed at youth suicide prevention since 1980 were analyzed. During 1992 and 1996, each governor was surveyed regarding his or her state's efforts in youth suicide prevention. Questions pertained to legislation, a mandated or recommended school-based suicide prevention curriculum, funding, a special advisory council, a state plan, the development and dissemination of materials, and assessment. Several states sent examples of their prevention activities, which were reviewed to determine the extent to which they represent conceptually and/or empirically grounded preventive intervention strategies. The number of suicides, suicide rates, and percentage change in rate for youth 15-19 years old were reported by state for the periods 1979-1981 and 1992-1994. The results of a repeated measures 2 x 5 ANOVA revealed that while changes in suicide rates over time were statistically significant, there was no relation between these changes and any of the variables studied. Suggestions for future research on state-level initiatives are presented.

Adolescent↗
PubMed1998

Remaining indications for total mastectomy in breast carcinoma

Does radical mastectomy for cancer remain needed? Breast conserving treatment may be achieved by surgery, primary chemotherapy followed by radiotherapy and surgery. This article attempts at defining (according to clinical and pathological parameters of the tumor and patient's characteristics), when conservative treatment is not allowed and radical mastectomy must be performed. Mastectomy must be performed first when there are multiple tumors or a tumor too large with respect to the breast volume or diffuse microcalcifications on mammograms.ometimes the stage of pregnancy, a personal history of collagen vascular disease or prior radiotherapy or the willing of the patient lead to perform radical mastectomy.econdary mastectomy is necessary in case of failure of conservative treatment or recurrence after breast conserving treatment.

Journal Article↗
PubMed1998

[Do indications remain for total mastectomy for cancer?].

Does radical mastectomy for cancer remain needed? Breast conserving treatment may be achieved by surgery, primary chemotherapy followed by radiotherapy and surgery. This article attempts at defining (according to clinical and pathological parameters of the tumor and patient's characteristics), when conservative treatment is not allowed and radical mastectomy must be performed. Mastectomy must be performed first when there are multiple tumors or a tumor too large with respect to the breast volume or diffuse microcalcifications on mammograms. Sometimes the stage of pregnancy, a personal history of collagen vascular disease or prior radiotherapy or the willing of the patient lead to perform radical mastectomy. Secondary mastectomy is necessary in case of failure of conservative treatment or recurrence after breast conserving treatment.

Breast Neoplasms↗
PubMed1997

Identification of three internalization sequences in the cytoplasmic tail of the 46 kDa mannose 6-phosphate receptor.

The cytoplasmic tail of the human 46 kDa mannose 6-phosphate receptor (MPR 46) is necessary for rapid internalization of the receptor and sufficient to mediate internalization of a resident plasma membrane protein. To localize the internalization sequences within the 67 amino acids of the cytoplasmic tail, the tail was progressively shortened from its C-terminus, internal deletions of between four and eight amino acids were introduced into the tail, and individual residues were substituted by alanine, glycine or serine. Three sequences were identified that contribute to the internalization of MPR 46. The first is located within the 23 juxtamembrane cytoplasmic residues of the tail. It contains four essential residues within a heptapeptide and does not resemble known internalization signals. The second sequence contains as a critical residue Tyr-45. The third region is located within the C-terminal seven residues and contains a di-leucine pair as essential residues. The first and third sequences were shown to function as autonomous internalization sequences. Substitution of critically important residues within a single internalization sequence was tolerated, with no or only a moderate decrease in the internalization rate. When essential residues from two or all three internalization sequences were substituted, however, the internalization rate was decreased by more than 60% and 90% respectively. This indicates that the autonomous internalization signals in the cytoplasmic tail of MPR 46 function in an additive manner, but are partly redundant.

Amino Acid Sequence↗