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.

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.

The effect of granulocyte-macrophage colony-stimulating factor (GM-CSF) on hepatitis B vaccination in haemodialysis patients

Haemodialysis patients often fail to respond to hepatitis B vaccination. In this pilot study, 15 patients previously non-responsive to at least three 40 micrograms doses of hepatitis B vaccine were given 0.5, 5 or 10 micrograms kg-1 granulocyte-macrophage colony-stimulating factor (GM-CSF) subcutaneously 24 h prior to booster vaccination with a hepatitis B vaccine. Seven of the 15 patients developed antibody to hepatitis B surface antigen (HBsAb) (35-7240 IU L-1) upon initial vaccination with GM-CSF and two of four individuals responded with low HBsAb titres of 15 and 60 IU L-1 when revaccinated with hepatitis B surface antigen (HBsAg) and twice the dose of GM-CSF. The application of GM-CSF was associated with adverse effects that were, in general, mild to moderate in severity and appeared to be dose dependent. Two patients, both receiving 10 micrograms kg-1 GM-CSF discontinued the study because of severe hypotension.

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.

Molecular cloning and disease association of hepatitis G virus: a transfusion-transmissible agent

An RNA virus, designated hepatitis G virus (HGV), was identified from the plasma of a patient with chronic hepatitis. Extension from an immunoreactive complementary DNA clone yielded the entire genome (9392 nucleotides) encoding a polyprotein of 2873 amino acids. The virus is closely related to GB virus C (GBV-C) and distantly related to hepatitis C virus, GBV-A, and GBV-B. HGV was associated with acute and chronic hepatitis. Persistent viremia was detected for up to 9 years in patients with hepatitis. The virus is transfusion-transmissible. It has a global distribution and is present within the volunteer blood donor population in the United States.

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.

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.

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.

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.

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.

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.

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.

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.

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.

Clinical significance of quantitative anti-HBc IgM assay in acute and chronic HBV infection

The applicability and clinical usefulness of anti-HBc IgM quantification in acute and chronic hepatitis type B by a single run of undiluted sera is largely unknown. Serum anti-HBc IgM concentrations were measured in 153 patients with various forms of acute and chronic HBV infection by a new commercially available qualitative ELISA/2-step capture assay applying streptavidin technology. The absorbance values were expressed in anti-HBc IgM U/ml using a calibration curve produced by a series of anti-HBc IgM standards. The results were compared with those obtained with another second generation qualitative anti-HBc IgM method also in undiluted sera applying the Microparticle Enzyme Immune Assay (MEIA). In acute hepatitis B, anti-HBc IgM was always > 600 U/ml (median: > 800 U/ml) declining to median values of 135 and 85 U/ml at months 3 and 6, respectively. Values above 600 U/ml were seen in 4 out of 20 (20%) HBsAg carriers with episodes of severe HBV-induced liver damage resembling acute hepatitis B (group 2) and in 2 out of 35 (5.6%) patients with HBV induced chronic active hepatitis (group 3). Values above 100 U/ml, representing the cutoff levels for the diagnosis of acute hepatitis B in the qualitative assays, were detected in 55% (11/20) and 45.7% (16/35) of the above patients of groups 2 and 3, respectively. Anti-HBc IgM was negative or under 20 U/ml in 96.7% (29/30) of HBsAg carriers with acute or chronic liver damage unrelated to HBV (HDV, HCV or drug-induced) and in 91% (41/45) of HBsAg carriers with persistently normal ALT levels.(ABSTRACT TRUNCATED AT 250 WORDS)

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.

Rotational and translational water diffusion in the hemoglobin hydration shell: dielectric and proton nuclear relaxation measurements

The dynamic properties of water in the hydration shell of hemoglobin have been studied by means of dielectric permittivity measurements and nuclear magnetic resonance spectroscopy. The temperature behavior of the complex permittivity of hemoglobin solutions has been measured at 3.02, 3.98, 8.59, and 10.80 GHz. At a temperature of 298 K the average rotational correlation time tau of water within a hydration shell of 0.5-nm thickness is determined from the activation parameters to be 68 +/- 10 ps, which is 8-fold the corresponding value of bulk water. Solvent proton magnetic relaxation induced by electron-nuclear dipole interaction between hemoglobin bound nitroxide spin labels and water protons is used to determine the translational diffusion coefficient D(T) of the hydration water. The temperature dependent relaxation behavior for Lamor frequencies between 3 and 90 MHz yields an average value D(298K) = (5 +/- 2) x 10(-10)m2 s-1, which is about one-fifth of the corresponding value of bulk water. The decrease of the water mobility in the hydration shell compared to the bulk is mainly due to an enhanced activation enthalpy.

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.

Virological and serological aspects of hepatitis B and the delta agent

The hepatitis B virus (HBV) belongs to a group of viruses termed hepadnaviruses. The 3.2 kb genome encodes for a variety of proteins involved in viral replication (p-gene), transactivation (x-gene), or encodes for structural proteins (c- and s-genes). Several viral and non-viral functions determine the clinical course of HBV infection. The hepatitis D virus resembles a viroid and requires the HBV as a helper virus. The interaction between the viruses is not well understood. More information on the interaction between the human host and viruses is needed to help improve the treatment.

Sub-acute effects of interferon-alpha 2 on adrenocorticotrophic hormone, cortisol, growth hormone and prolactin in humans

This study investigated the chronic effects of interferon-alpha 2 (IFN-alpha 2) on hormonal secretion in humans. Six patients suffering from chronic hepatitis B or C infection received SC doses of 3 million IU IFN-alpha 2 three times a week for 4 mo. Each patient was examined for hormone secretion four times: the day before initial IFN-alpha 2 administration (day 0), the day of the first injection (day 1), and 4 wk after start of IFN therapy on days 27 (without IFN administration) and 28 (with IFN administration). Adrenocorticotrophic hormone (ACTH), cortisol, growth hormone (hGH), and prolactin (PRL) were measured in plasma samples drawn at 30-min intervals between 1600h and 2400h. Acute administration of IFN-alpha 2 stimulated the release of ACTH to 423% (p = 0.02 vs. day 0) and cortisol to 393% (p = 0.01 vs. day 0) of control values in each patient. In five of the six patients, the plasma levels of hGH were higher on day 1 than on day 0. IFN-alpha 2 did not affect the secretion of prolactin. On day 27, the plasma levels of the four hormones were similar to the baseline levels on day 0. When IFN-alpha 2 was given on day 28, there were no significant differences in the release of ACTH (135% of control, p = 0.4) or cortisol (124% of control, p = 0.5) in comparison to day 27. These findings indicate that IFN-alpha 2 stimulation of hormone release is restricted to specific hormones.(ABSTRACT TRUNCATED AT 250 WORDS)

Antiviral effect of prolonged intermittent lymphoblastoid alpha interferon treatment in chronic hepatitis B

In a European multicentre study 40 patients with HBeAg positive chronic hepatitis B virus (HBV) infection were treated with 5 mega units of lymphoblastoid alpha-interferon daily according to the following regimen: a four week primer course, four weeks of rest and a second course lasting 16 to 30 weeks. After 52 weeks of follow up, a response (HBeAg seroconversion and HBV-DNA negativity) was observed in 22 patients (55%). HBsAg seroconversion occurred in five patients (12.5%). One patient exhibited a relapse for serum HBeAg and HBV-DNA after cessation of treatment. According to a response prediction model, the observed response rate was not related to the selection of patients likely to respond. The initial interferon course induced a reduction of the serum HBV-DNA and HBeAg levels of 87% and 18%, respectively, leading to a significantly lower level of viral replication activity at the start of the second longterm course compared with baseline. After 24 weeks of follow up (week 16 of the second course), 19 (48%) patients exhibited a response, 13 (32%) a partial response (HBeAg < 50% of initial level or HBV-DNA negative) and 8 (20%) no response. For eight of the 13 partial responders treatment was stopped at week 24 and viral replication rebounded to pretreatment values. In the last five partial responders prolongation of therapy up to week 38 led to a definite response and HBsAg seroconversion in three of the five patients. The results of this study suggest that a short primer course and prolongation of therapy may help to enhance the response rate of alpha-interferon therapy for chronic hepatitis type B.

Hepatitis B and C in heterosexual patients with various sexually transmitted diseases

The seroprevalence of hepatitis B virus (HBV) and hepatitis C virus (HCV) infections were prospectively assessed in 356 heterosexuals with STDs (sexually transmitted diseases) and compared to a control group of 381 healthy first-time blood donors. Eighty-one of 356 STD patients were anti-HBC positive (22.8%) compared to 14/381 blood donors (3.8%; p less than 0.001). In addition, 18 of the 81 anti-HBC positive STD patients, but none of the controls, were positive for HBSAg (p = 0.06). The prevalence for anti-HCV was also significantly higher in the STD group than in the controls (5.3% vs. 0.5%; p less than 0.001). Among the various STDs syphilis (anti-HBC: 67.5%; anti-HCV: 12.5%) and Chlamydia trachomatis infections (anti-HBc: 20.2%, anti-HCV: 8.1%) had the highest prevalence for both infections. This study provides strong evidence of heterosexual transmission of hepatitis B and C virus infections. Thus, heterosexuals with STDs or multiple partners should be actively vaccinated against hepatitis B.

Statistical analysis of long-term potentiation of large excitatory postsynaptic potentials recorded in guinea pig hippocampal slices: binomial model

Excitatory postsynaptic potentials (EPSPs) were recorded in guinea pig hippocampal slices (area CA1) from 15 neurons after stimulation of stratum radiatum (str. rad.) and stratum oriens. EPSP amplitudes increased in 8 neurones (10 post-tetanic regions) recorded 15 to 45 min after tetanic stimulation of str. rad. The increase was considered to represent long-term potentiation (LTP). Quantal analysis was performed by two methods assuming binomial statistics: the histogram method using deconvolution of noise and the variance method. According to both methods, LTP was associated with an increase in mean quantal content (m) which correlated with LTP magnitude. A statistically significant increase in quantal size (v) was found only by the histogram method and the increase was not correlated with LTP magnitude. A separate analysis of EPSPs with small LTP magnitude demonstrated that with the histogram method only v was increased but not m. A smaller increase in m for the pooled data of both methods did not correlate with LTP magnitude for this EPSP subset. The increase in m for the whole EPSP set corresponds to previous results on the quantal analysis of LTP in in vivo preparations and favours a presynaptic location of major mechanisms underlying LTP maintenance. The increase in v indicates the existence of another mechanism responsible for the maintenance of a small part of LTP. This mechanism might involve either pre- or postsynaptic changes or both.

Quantal analysis of long-term potentiation of "minimal" excitatory postsynaptic potentials in guinea pig hippocampal slices: binomial approach

"Minimal" excitatory postsynaptic potentials (EPSPs) were recorded from 13 neurones in area CA1 of guinea pig hippocampal slices after double-pulse stimulation of stratum radiatum (str. rad.) and stratum oriens (str. or.). Amplitudes of EPSPs significantly increased in 8 neurones 5 to 55 min after 9 tetanizations in str. rad.. The increase was considered to represent long-term potentiation (LTP). Altogether 26 EPSPs (42 post-tetanic regions) were statistically analysed by four methods of the quantum hypothesis assuming the binomial model of transmitter release: the deconvolution (histogram), the variance, the failures, and the combined (variance-failures) methods. The mean quantal content (m) significantly increased after LTP induction according to all methods used. Quantal size (v) also tended to increase but according to some methods, the increase was not statistically significant and it did not correlate with LTP magnitude. However, for an EPSP subset with a LTP magnitude of less than 1.55, the increase in v correlated with LTP magnitude, whereas the increase in m did not. The relative contribution of the increase in v to LTP magnitude was larger for cases with small LTP than for the whole EPSP set. In general, the increase in m corresponds to previous studies and favours the presynaptic location of major mechanisms of LTP maintenance, i.e. an increase in the average number of transmitter quanta released by each presynaptic volley. The post-tetanic increase in v might reflect some additional mechanisms which presumably include an increase in the amount of transmitter in one quantum.