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G Hess

Publications and source records attributed to G Hess.

At least 73 records · Page 4Linked to original sources
PubMed1996

Hepatitis G virus RNA in the serum of patients with elevated gamma glutamyl transpeptidase and alkaline phosphatase: a specific liver disease? [corrected].

We tested the sera of 67 consecutive patients for hepatitis G virus (HGV) RNA by reverse transcriptase-polymerase chain reaction (RT-PCR). These patients (42 males and 25 females, median age 35 years, range 13-64 years) had liver disease of unknown aetiology and were without markers of hepatitis (A-E) viruses or signs of genetically determined, autoimmune, alcoholic or drug-induced liver disease. The controls in this study were 110 patients (50 females and 60 males, median age 45 years, range 9-65 years) with chronic hepatitis B virus (HBV) infection (19 patients) or hepatitis C virus (HCV) infection (91 patients). Ten of 67 (14.9%) patients with cryptogenic disease were positive for HGV RNA by at least three separate tests; HGV RNA was also detected in one of 19 (5.3%) hepatitis B surface antigen (HBsAg) carriers and in nine of 91 (16.6%) patients with antibody to HCV. These data suggest that HGV occurs as frequently in HCV-infected patients as in those with cryptogenic disease. Elevated serum gamma glutamyl transpeptidase (gamma-GT) (higher than twice the normal value) and alkaline phosphatase levels were found in eight of 10 (80%) HGV RNA positive patients and in six of 57 (10.5%) HGV RNA negative patients (P < 0.0001). Five (50%) HGV RNA positive patients had non-specific inflammatory bile duct lesions. A statistically significant difference was observed between HGV RNA positive and negative patients with chronic HBV or HCV infections (P < 0.029). Therefore, the spectrum of liver disease associated with HGV is wide, but a characteristic lesion of the bile duct leading to elevation of cholestatic enzymes might be specific for this virus.

Adolescent↗
PubMed1996

Long-term depression of horizontal connections in rat motor cortex.

The possibility for long-term depression (LTD) of synaptic transmission in layer II/III horizontal connections within motor cortex was investigated using field potentials and intracellular recordings in rat brain slices. The LTD was induced by low-frequency stimulation at 2 Hz for 10 min in sites displaced horizontally by 0.5 mm from the stimulating electrode. Response amplitude measured 25-30 min after 2 Hz stimulation ended was 79% of baseline values (n = 13) at half maximal stimulation and 59% when 2 Hz stimulus intensity was doubled (n = 10). In 13/15 tested cases LTD in horizontal connections was specific to the activated pathway. Intracellular recordings from six neurons confirmed synaptic character of response depression. Horizontal connections in which LTD was induced retained the capability of increasing synaptic strength. Long-term potentiation could be induced in previously depressed pathways by simultaneous theta burst stimulation of two converging horizontal inputs combined with transient local application of GABA(A) receptor antagonist bicuculline methiodide (mean increase: 45 +/- 8% n = 6) or by simultaneous theta burst stimulation of converging horizontal and vertical inputs (mean change: 26 +/- 6%, n = 5). These data demonstrate that activity-dependent mechanisms may regulate bidirectionally the effectiveness of horizontal synaptic coupling between cortical neurons, thus forming a potential mechanism for plasticity of cortical connections and the representation patterns they support.

Action Potentials↗
PubMed1996

Analysis of the p53 and MDM-2 gene in acute myeloid leukemia.

The MDM-2 (murine double minute 2) gene codes for a cellular protein that can bind to the p53 tumor suppressor gene product, thereby functioning as a negative regulator of p53. In order to define the role of the MDM-2 gene in the pathogenesis of human acute myeloid leukemia, the expression and the sequence of the MDM-2 gene were examined in samples of bone marrow and/or peripheral mononuclear cells of 38 patients by using immunostaining, polymerase chain reaction (PCR), single strand conformation polymorphism, and sequencing. Immunohistochemical staining detected a weak accumulation of the MDM-2 protein in AML patients of FAB classification M4 and M5. RT-PCR analysis revealed a heterogeneous expression pattern of MDM-2 mRNA in AML samples of different FAB classification. An increased level of MDM-2 mRNA expression was observed in 17 of 38 AML patients when compared to normal controls. No structural changes in a 488 bp region extending from nucleotide 890 to 1378 of the MDM-2 cDNA were detected using RT-SSCP and sequence analysis. In addition, heterogeneous expression of p53 transcripts was found with the highest p53 mRNA levels in AML M4 and M5. Interestingly, there seems to be a correlation between the relative ratios of p53 and MDM-2 mRNA levels in AML M4 and M5: in 15 of 23 cases high p53 mRNA expression was directly associated with high levels of MDM-2 transcripts. An exclusively intranuclear p53 immunostaining pattern was found in 10 of 16 (58%) AML FAB M4 and M5, whereas the remaining AML samples tested were negative for p53 (0/10). Using RT-SSCP analysis and direct sequencing of the RT-PCR amplification products of p53 exon 5-8, we observed that only 1 of 38 AML patients showed a point mutation in the p53 gene. This missense mutation occurred in the evolutionary highly conserved region of p53 at codon 255 (Ile to Phe). These data indicated that structural alterations of the p53 gene do not play an important role in the initiation and progression of AML. However, abrogation of p53 tumor suppressor function due to MDM-2 overexpression may be an alternative molecular mechanism by which a subset of AMLs may escape from p53-regulated growth control.

Acute Disease↗
PubMed1996

Reverse transcription-PCR detection of hepatitis G virus.

Hepatitis G virus (HGV) was recently identified as a new member of the Flaviviridae, but its clinical significance is still unclear. Since no immunoassay for the diagnosis of HGV is available, we developed a sensitive reverse transcription-PCR (RT-PCR) assay to facilitate the detection of the viral genome by mass screening in the clinical laboratory. Sequences within the 5'-noncoding region and within the putative NS5a region are independently amplified in the presence of digoxigenin-11-dUTP and are detected by hybridization with biotinylated capture probes binding to a streptavidin-coated matrix. Semiquantitative Enzymun-Test DNA detection via chemiluminescence can be performed either in a microtiter plate format or on fully automated ES 300 machines. We were able to detect at least 8 x 10(2) genome equivalents per ml of serum using both primer pairs. HGV was shown to be present in 43 of 130 (33%) serum samples from intravenous drug abusers with a high risk of parenteral exposure. However, only two of the patients were positive when the NS5a primers only were used, and only one patient was positive when only the 5'-noncoding region primers were used, demonstrating the increased sensitivity of HGV detection with two sets of primers. Among these patients, there was no obvious correlation with other viral infections like hepatitis B virus, hepatitis C virus, or human immunodeficiency virus. Within a blood donor panel, 3 of 92 (3%) samples were found to be HGV positive, suggesting that donated blood may need to be screened for HGV.

Base Sequence↗
PubMed1996

Quantitative detection of human immunodeficiency virus (HIV) antigen by the Enzymun-Test: comparison with alternative assays and nucleic acid sequence-based amplification of HIV type 1 RNA.

A new modular automated enzyme immunoassay (EIA) (Enzymun-Test HIV Ag: Boehringer Mannheim) for quantitative human immunodeficiency virus (HIV) antigen detection was evaluated by testing a panel of 1,506 serum samples, including seroconversions, dilution series, follow-up samples from patients under antiretroviral therapy, single serum specimens from HIV-seropositive individuals in different stages of infection, potentially cross-reactive samples, and sera from HIV-negative hospitalized patients. The Abbott HIV type 1 (HIV-1) antigen monoclonal antibody assay served as the reference assay, and nucleic acid sequence-based amplification (Organon Teknika) for quantitative amplification of HIV-1 RNA was used for follow-up of patients under antiretroviral chemotherapy. The Boehringer Mannheim and Abbott EIAs showed concordant results for the early detection of HIV antigen in all the seroconversion panels. The follow-up samples from 29 HIV-infected individuals under antiretroviral therapy gave divergent results between both antigen tests. For the detection of HIV antigen in single serum samples from HIV-infected patients in different stages of HIV infection, a higher number of positive samples was detected with the Abbott HIV-1 antigen monoclonal antibody assay in samples from patients in stages II and III of HIV infection. The Enzymun-Test detected three or more positive samples than did the Abbott assay among the samples of patients with AIDS. The concordance on a sample-to-sample basis between the Boehringer Mannheim and Abbott EIAs was 98.6%. The sensitivity of the Enzymun-Test in comparison to the reference assay was 97.2%; the specificity was 98.8%. Although no close correlation could be found between the amount of viral RNA in serum detected by nucleic acid sequence-based amplification and the concentration of HIV antigen, a high HIV-1 RNA copy number was mostly associated with high levels of HIV antigen. In conclusion, the Enzymun-Test permits accurate HIV antigen detection and offers, in contrast to previous assays, the possibility of completely automated detection.

AIDS Serodiagnosis↗
PubMed1996

Conditions for the induction of long-term potentiation in layer II/III horizontal connections of the rat motor cortex.

1. The present studies investigated conditions for the induction of long-term potentiation (LTP) in the local horizontal pathways of layers II/III in the primary motor cortex (MI) of the adult rat. Field potential and intracellular recordings demonstrated synaptic interactions across the superficial layers within MI that could be enhanced transiently by focal application of the gamma-aminobuturic acid-A receptor antagonist bicuculline methiodide (Bic) at the recording site. 2. Field potentials evoked in the superficial MI horizontal pathways increased in amplitude after tetanizing, theta burst stimulation (TBS), but only when Bic was applied transiently at the recording site immediately before TBS. In the absence of Bic, TBS failed to produce long-lasting increases in horizontally evoked field responses. By contrast, TBS delivery during focal Bic application increased field potential amplitudes by 25-35% when measured 25-30 min after stimulation. The amount of potentiation was greater when two converging horizontal inputs were stimulated together but was not increased with higher intensity stimulation. Persistent effects of Bic application alone were evident. However, these effects were small unless Bic application continued until evoked field potential amplitude increase exceeded 200% of baseline. 3. The synaptic nature of field potential increases were confirmed using intracellular recordings of layer II/III neurons located near field potential electrodes. 4. LTP also could be induced without Bic application by cotetanization of vertical pathways simultaneously with horizontal activation. Vertical conditioning alone at 2 Hz, which affects inhibitory efficacy, was shown to transiently relieve depression of successive responses that ordinarily occurs during a burst of three horizontal stimuli. These results suggest that LTP of horizontal pathways may be regulated by spatiotemporal interactions between horizontal and vertical pathways. 5. Horizontal LTP was blocked reversibly by bath application of the N-methyl-D-aspartate (NMDA) antagonist 2-amino-5-phosphonovaleric acid, thereby implicating NMDA-receptor activation in LTP induction for these pathways. 6. The results confirm and extend our previous finding that the potential for activity-dependent modification of synaptic connections exists within the intrinsic horizontal connections of the superficial cortical layers. Synaptic modification across horizontally connected neurons appears to be regulated both by the arrangement of intrinsic circuitry and by the availability of mechanisms for modification at individual synapses. The properties of horizontal connections indicate that they form a spatial substrate and provide an activity-dependent mechanism for plasticity of adult cortical representations.

2-Amino-5-phosphonovalerate↗
PubMed1996

Long-term potentiation and long-term depression of horizontal connections in rat motor cortex.

This paper reviews studies that investigate conditions resulting in long-lasting modifications of synaptic efficacy in horizontal connections within layers II/III of adult rat motor cortex using the in vitro slice preparation. Long-term potentiation (LTP) was induced by high frequency theta burst stimulation (TBS) when local synaptic inhibition was transiently suppressed by bicuculline methiodide application at the recording site immediately prior to TBS of the horizontal pathway. Without bicuculline, TBS failed to produce LTP. LTP could also be induced without Bic application by conjoint TBS of horizontal and vertical (ascending) inputs. By contrast, long-term depression (LTD) of horizontal transmission was induced by 10 min of 2 Hz stimulation. Depressed horizontal connections nevertheless retained the capability for synaptic strength increases. These studies indicate that synaptic modification across horizontally connected neurones is regulated both by the arrangement of their intrinsic circuits and by the availability of mechanisms for modification at individual synapses. Activity dependent forms of synaptic plasticity operating within horizontal connections may form a spatial substrate and mechanism for experience-dependent regulation of cortical representations.

Animals↗
PubMed1996

Cholinergic modulation of synaptic transmission in horizontal connections of rat motor cortex.

The influence of compounds interacting with cholinergic systems on field potentials evoked in layer II/III horizontal connections was investigated in rat motor cortex in vitro. The cholinesterase inhibitor eserine (10 microM) decreased field responses by 20 +/- 2%. This effect could be prevented by preincubation with atropine (10 microM). Application of 5 microM carbachol resulted in reduction of the responses by 30 +/- 1%. These reductions were reversible, repeatable and independent of stimulus intensity; they could be blocked by the M1 muscarinic receptor antagonist pirenzepine (3 microM) but not by the M2 muscarinic receptor antagonist gallamine (10 microM). During carbachol application, paired-pulse facilitation (40 ms interpulse interval) was increased. The results indicate that endogenous acetylcholine may modulate excitatory synaptic transmission in horizontal connections of rat motor cortex, most likely by acting upon M1 receptors located presynaptically on glutamatergic terminals, and may contribute both to information processing and synaptic plasticity within the motor cortex.

Animals↗
PubMed1996

Sustaining, protecting and promoting public health in Bosnia and Herzegovina.

Four years of war in Bosnia and Herzegovina have severely damaged the health care system and destroyed basic infrastructures. Yet in spite of these conditions and the reappearance of several "dormant" diseases, no major fatal disease outbreaks have occurred. Morbidity and mortality due to infectious diseases have remained surprisingly low. This article explores some of the reasons why this potentially enormous public health disaster was avoided. Public health interventions can generally be considered the outcome of two components: knowledge and action. War situations inhibit thorough or ideal data collection and therefore the balance between knowledge and action must be tipped towards the latter. In Bosnia and Herzegovina, the WHO/national health monitoring system maintained a sufficient level of surveillance so as to provide early detection of significant threats to health. As the lead health agency in the conflict, WHO applied several health monitoring strategies. Major fatal epidemics were avoided because health workers have become increasingly scientific in predicting epidemics in war situations and formulating the steps necessary to limit them. Some of the preventive interventions applied in Bosnia and Herzegovina to reduce the impact of infectious diseases are discussed.

Bosnia and Herzegovina↗
PubMed1995

Immunogenicity and safety of an inactivated hepatitis A vaccine in anti-HIV positive and negative homosexual men.

The immunogenicity, reactogenicity, and safety of an inactivated hepatitis A vaccine were assessed in anti-HIV positive homosexual men. Fourteen anti-HIV positive (group 1) and 20 anti-HIV negative (group 2) men received vaccine (containing 720 ELISA units of hepatitis A antigen per dose) intramuscularly at 0, 1, and 6 months. Twelve unvaccinated anti-HIV positive men (group 3) were included as controls to evaluate disease progression. Seroconversion (anti-hepatitis V virus (HAV) > or = 20 mlU/ml) was higher in group 2 than group 1 at months 2 (100% vs. 73%) and 7 (100% vs. 77%). Group 2 had higher antibody titres than group 1 at months 1 (201 vs. 92 mlU/ml) and 7 (1,687 vs. 636 mlU/ml). The decline in CD4+ cells between months 0 and 7 was similar in groups 1 and 3 (6.4% vs. 16.2%), showing no evidence for harmful effect of the vaccine on the course of HIV infection. This hepatitis A vaccine appears safe, well tolerated, but less immunogenic in HIV positive homosexual men.

Acquired Immunodeficiency Syndrome↗
PubMed1995

Analysis of immunoassays to detect antibodies to hepatitis A virus (anti-HAV) and anti-HAV immunoglobulin M.

Two newly developed anti-HAV tests were assessed, using a total of 1835 sera. These two tests are being distributed under the trademarks Enzymun-Test anti-HAV and Enzymun-Test IgM anti-HAV. The anti-HAV test was compared to anti-HAV tests from other manufacturers and featured a high sensitivity combined with a high level of reproducibility and specificity. In terms of sensitivity, reproducibility and specificity, the IgM test proved to be comparable to other IgM anti-HAV tests used for the diagnosis of acute type A hepatitis. Combining both tests was shown to be useful to recognize an acute or past hepatitis A virus infection. In addition, the high sensitivity of the anti-HAV test makes this test extremely useful to assess the immunoresponse to the hepatitis A vaccine.

Female↗
PubMed1994

N-methyl-D-aspartate receptor mediated component of field potentials evoked in horizontal pathways of rat motor cortex.

To identify potential sites of synaptic modification of intrinsic cortical circuits, the contribution of the N-methyl-D-aspartate type of glutamate receptors to field potentials evoked in horizontal and oblique intracortical pathways was examined in rat motor cortex slice preparations. Presumably monosynaptic, short latency responses with a prominent negativity (-0.4 to -2.0 mV) were recorded in both superficial (across layer III) and deep (across layer V) horizontal pathways at a distance of approximately equal to 500 microns lateral to electrical stimulation sites and in oblique V-III pathway (-0.3 to -1.6 mV). Bath application of the N-methyl-D-aspartate receptor antagonist D,L-2-amino-5-phosphonovaleric acid (100 microM) reversibly decreased field potentials. Although decreases were observed in all components of the waveform, the most pronounced effect was on the late phase of the response. D,L-2-Amino-5-phosphonovaleric acid produced on average a 22% decrease in area, 12% in initial slope and 11% in peak amplitude of responses. Combined application of 100 microM D,L-2-amino-5-phosphonovaleric acid and a non-N-methyl-D-aspartate glutamate receptor antagonist, 6-cyano-7-nitro- or 6,7-dinitro-quinoxaline-2,3- dione (10-20 microM), eliminated all but a small, early and presumably non-synaptic response. In 18 of 23 cases, the relative contribution of the D,L-2-amino-5-phosphonovaleric acid-sensitive component was unrelated to field potential magnitude, suggesting that this component is present in all fiber classes. It is concluded that glutamate is the major transmitter of horizontal connections of layers II/III and layer V, as well as in the oblique V-III pathway. While most glutamatergic transmission is relayed by other glutamate receptor subtypes, N-methyl-D-aspartate receptor activation contributes a small but consistent part of ordinary transmission in each of these pathways in vitro. The results further suggest that a potential for N-methyl-D-aspartate receptor-mediated synaptic modification exists in intrinsic horizontal pathways of both superficial and deep layers of rat motor cortex.

2-Amino-5-phosphonovalerate↗
PubMed1994

Molecular analysis of the erythropoietin receptor system in patients with polycythaemia vera.

Erythropoietin (EPO) is a potent regulator of the viability, proliferation and differentiation of erythroid progenitor cells. Its effect is mediated by binding to the erythropoietin receptor (EPO-R), a member of a new cytokine receptor family. Alterations of the EPO/EPO-R system have recently been shown to be involved in the pathogenesis of familial erythrocytosis and polycythaemia vera (PV). In order to define whether genetic changes in the EPO-R gene and its ligand play a role in the development of PV, the structure and expression levels of the EPO-R and EPO genes were examined in samples from bone marrow and/or peripheral blood mononuclear cells of 24 patients with PV. As expected, EPO serum levels were low and no detectable level of EPO mRNA was found by reverse polymerase chain reaction (RT-PCR) in the peripheral blood mononuclear cells of our PV patients. To search for structural alterations of the EPO-R, cDNA samples were subjected to PCR and SSCP analysis as well as sequencing. Heterogenous expression of EPO-R mRNA was observed without any structural changes, as revealed by RT-SSCP analysis using overlapping primers spanning the whole coding region of the EPO-R gene. Structural integrity of the EPO-R was further confirmed by sequencing of cloned PCR products. These data suggest that the mechanisms for the development of PV do not involve structural changes of the EPO-R gene.

Adult↗
PubMed1994

Diagnosis of human immunodeficiency virus (HIV) infection: multicenter evaluation of a newly developed anti-HIV 1 and 2 enzyme immunoassay.

A new anti-human immunodeficiency virus type 1 and 2 (anti-HIV 1 and 2) test is described. It uses recombinant p24 and peptides covering gp32, gp41, and gp120 to identify HIV-1 and HIV-2 infections. This test has been shown to be specific (99.5%) and sensitive (99.8%). In this respect, the assay was equal or superior to anti-HIV 1 and 2 tests run as references. The test was able to discriminate sera from patients with HIV infections from those from uninfected individuals with excellence; it also exerted high intra- and interassay precisions. The "modular" concept of the test allows the use of single components (gp32 or gp41) to separate between HIV-2 and HIV-1 infections, respectively.

Diagnosis, Differential↗
PubMed1994

Long-term potentiation of horizontal connections provides a mechanism to reorganize cortical motor maps.

1. Field potential recordings were used in rat motor cortex (MI) slice preparations to investigate the potential for activity-dependent modifications in the effectiveness of synaptic connections formed by layer II/III horizontal projections. 2. Long-term potentiation (LTP) of synaptic efficacy in MI horizontal pathways could be produced at short (0.5 mm) and long (1.0 mm) distances by theta burst stimulation (TBS), but only during local, transient application of the gamma-aminobutyric acid-A (GABAA) receptor antagonist, bicuculline methiodide (bic) immediately before TBS. Mean increase of the field potential amplitude measured 25-35 min after LTP induction ranged between 24 and 34%. Cooperative effects of conjoint TBS of two horizontal pathways on LTP induction were observed. 3. These results demonstrate that persistent changes in the functional interactions of cortical neurons can arise by activity-dependent mechanisms within the local horizontal connections and suggest a likely mechanism to recognize cortical representation patterns.

Animals↗
PubMed1993

Toward routine diagnosis of hepatitis B virus desoxyribonucleic acid.

Although a multitude of hepatitis B markers are available to discriminate different states of hepatitis B virus (HBV) infection, there remains a need to detect the HBV DNA itself. The HBV DNA test is the only test that can quantify the number of complete virions. As shown in this review, the diagnostic value of testing for HBV DNA depends on quantification, and there are situations in which in vitro amplification is necessary and others in which testing for HBV DNA without preamplification is best. Indications for analysis of HBV DNA include the early recognition of chronic hepatitis B, discrimination of different HBsAg carrier states, recognition of the evolution of variants, indication and follow-up of anti-viral therapy with interferon, and assessment of blood products for infectivity. In each of these cases quantification of HBV DNA improves the diagnosis of HBV infection and will become an important tool in the routine diagnosis of hepatitis B virus infection in the future.

Acute Disease↗
PubMed1993

Evaluation of the automated 'Enzymen-Test Anti HIV-1 + 2' and 'Enzymen-Test Anti HIV-1/2 selective' for the combined detection and differentiation of anti-HIV-1 and anti-HIV-2 antibodies.

A new, modular automated ELISA (test 1) for HIV-1 and HIV-2 antibody detection and differentiation (Enzymun-Test Anti HIV-1 + 2; anti HIV 1/2 selective, Boehringer Mannheim) was compared with 3 alternative enzyme immunoassays (Abbott recombinant HIV-1/HIV-2 3rd generation EIA, Abbott (test 2); Enzygnost HIV 1 + 2, Behringwerke (test 3); and Wellcozyme HIV recombinant, Murex (test 4)) and Western blot (New LAV I Blot and New LAV II Blot; Diagnostics Pasteur). 380 serum samples from HIV-1 and HIV-2 seropositive patients at different stages of disease, high risk individuals, patients with conditions unrelated to AIDS and from healthy blood donors were used in this evaluation along with 6 seroconversion panels, 6 serum dilution series and 'tricky' sera (repeatedly positive results in ELISA, but negative or undeterminate in Western blot; n = 67). Using the Western blot as reference assay, the overall sensitivity of the four ELISAs was 100%. Test 4 showed the highest sensitivity for antibody detection in seroconversion and dilution series. A high specificity was achieved with test 1 (100%) and test 2 (99.4%). A relatively high rate of false positive results were obtained with test 2 (n = 12) and test 3 (n = 10) by testing 'tricky' sera or samples obtained from healthy blood donors. In comparison to Western blot, a clear differentiation between HIV-1 and HIV-2 antibody serum samples was achieved with the Enzymun-Test. The results of the present study show that the Enzymun-Test provides reliable selective HIV-1 and HIV-2 antibody detection at a cost which is significantly lower than the costs of Western blot tests. Furthermore, the evaluation of test 1 suggests, that it is a highly specific assay for HIV antibody detection.

AIDS Serodiagnosis↗