Development of the formalin-inactivated hepatitis A vaccine, VAQTA from the live attenuated virus strain CR326F

The development of the formalin-inactivated hepatitis A vaccine, VAQTA, culminates nearly two decades of the basic science studies of VAQTA in hepatitis A virology at the MRL. The master seed virus for production of VAQTA is derived from the F'(P18) variant of the strain CR326F which has been studied in human clinical trials and shown to the highly attenuated. The antigen is highly purified to make possible the consistency and thoroughness of its inactivation by formalin. Phase I clinical studies of VAQTA were initiated in 1989 and have progressed since that time to the recent Phase III clinical trials which demonstrated efficacy of a single dose of the vaccine in preventing clinical hepatitis A disease in pediatric populations in Monroe, NY.

Acetylcholine receptor molecules of the nematode Caenorhabditis elegans

Receptors for acetylcholine are present in nematodes. Studies using physiological and biochemical methods have revealed the existence of nicotinic acetylcholine receptors with a novel pharmacology. Caenorhabditis elegans provides a particularly suitable organism with which to investigate such receptors using molecular genetic approaches. Mutants resistant to the cholinergic agonist (and anthelmintic drug) levamisole have permitted the isolation of a number of genes, including structural subunits of the nicotinic acetylcholine receptor. The only known viable mutants of nicotinic receptors are those of Caenorhabditis elegans. This organism offers the prospect of studying the developmental and regulatory effects of the loss of a single component of the receptor. Using Caenorhabditis elegans it is possible to select interesting phenotypic mutations by in vivo mutagenesis before determining the causative lesion. Resistance genes other than those encoding structural subunits are of particular interest, as they will encode additional polypeptides closely associated with nicotinic receptor function. Such proteins are often difficult or impossible to identify using conventional biochemical approaches, whereas genetic selection should permit their identification.

Childhood precursors of affective vs. social deficits in adolescents at risk for schizophrenia

Childhood attentional and neuromotor precursors of social competence and affective deficits in adolescents at risk for schizophrenia, adolescents at risk for affective disorder, and matched comparison adolescents were examined. The subjects were offspring of parents with schizophrenia or affective disorder and of normal parents matched on age, sex, and socioeconomic status from the New York High-Risk Project (Sample B). On the basis of interviews conducted when the subjects were children and adolescents, social competence was rated from child reports and parent reports, affective deficits were assessed by affective flattening ratings, and smiling was assessed by counting broad smiles. Adolescents at risk for schizophrenia had significantly greater social and affective deficits than adolescents at risk for affective disorder and comparison adolescents. In subjects at risk for schizophrenia, childhood neuromotor dysfunction predicted adolescent affective flattening, and childhood attentional dysfunction predicted adolescent social deficits. The results suggest that affective and social deficits in schizophrenia have different childhood precursors.

Single and booster dose responses to an inactivated hepatitis A virus vaccine: comparison with immune serum globulin prophylaxis

Pre- and postexposure prophylaxis against hepatitis A virus (HAV) infection with immune serum globulin (Ig) is only effective for 4-6 months. We compared the safety, tolerability and immunogenicity of a single i.m. injection of Ig with a single and booster dose of an inactivated hepatitis A virus vaccine (iHAV) in adults. Healthy volunteers (18-50 years) received a single Ig i.m. injection (n = 30), or iHAV i.m. (n = 15) at 0 and 24 weeks, or placebo (n = 4) at the same intervals. Anti-HAV seroconversion was measured by radioimmunoassay (RIA) and neutralizing antibodies by an antigen reduction assay. After Ig injection (0.06 ml/kg), anti-HAV seroconversion occurred in 100% of recipients at week 1, declining to 10% at week 12 and 0% by week 20. In contrast, after a single 25 ng dose, RIA seropositivity in iHAV vaccinees was 80% by week 2, reaching 100% by week 5 and persisted up to week 24, at which time anti-HAV geometric mean titres (GMT) were two fold higher than those seen at week 1 after Ig. Postbooster anti-HAV titres in iHAV recipients rose within 4 weeks to 73-fold greater than the peak GMT seen one week after Ig, and 400-fold higher than GMT at 12 weeks after Ig. Neutralizing antibody titres after iHAV followed a similar pattern, as observed for anti-HAV. iHAV was well tolerated; placebo and vaccine tolerability were indistinguishable, with no serious adverse experiences observed. In conclusion, active vaccination with a single iHAV dose may eventually replace Ig for pre-exposure prophylaxis.(ABSTRACT TRUNCATED AT 250 WORDS)

Safety, tolerability, and immunogenicity of an inactivated hepatitis A vaccine: effects of single and booster injections, and comparison to administration of immune globulin

Hepatitis A virus (HAV) infection in adults is often symptomatic and disabling. The present article summarizes our experience with phase 2 studies of an inactivated hepatitis A virus vaccine. Pre- and post-exposure prophylaxis with immune globulin (IG) is only effective for 4-6 months. We compared the safety, tolerability, and immunogenicity of a single i.m. injection of IG with single and booster doses of an inactivated hepatitis A virus vaccine (iHAV) in adults. A total of 75 healthy volunteers (aged 18-50 years) were evaluated in two separate studies. The first included 15 volunteers who received 25 units iHAV i.m. at 0 and 24 weeks. The second, a randomly controlled study, consisted of three groups receiving 25 units iHAV i.m. at 0, 1, and 6 months, or at 0, 2, and 6 months, or 0.06 ml/kg IG i.m. given once. Anti-HAV seroconversion was measured by radioimmunoassay (RIA). After IG injection, anti-HAV seroconversion occurred in 100% of recipients at week 1, declining to 10% at week 12, and 0% by week 20. In contrast, after a single 25-unit dose, RIA seropositivity in iHAV vaccines was 73% by week 2, reaching 100% by week 5, and persisted in all up to week 24, at which time anti-HAV geometric mean titers (GMT) were 2-fold higher than those seen at week 1 after IG. Administration of a booster dose given 1 or 2 months after primary immunization did not significantly improve the quantitative anti-HAV response at 6 months as compared to the effect of the primary dose.(ABSTRACT TRUNCATED AT 250 WORDS)

A detergent-solubilized nicotinic acetylcholine receptor of Caenorhabditis elegans

We have used a spin column assay to study the detergent-solubilized levamisole receptor, a nicotinic acetylcholine receptor of the nematode Caenorhabditis elegans. The receptor can be successfully solubilized in detergent solutions of Triton X-100, Lubrol PX, or sodium cholate. Centrifugal gel filtration assay using the tritiated ligand [3H]meta-aminolevamisole ([3H]MAL) provides a greater signal and a better signal-to-noise ratio for soluble levamisole receptor binding than either polyethylene glycol precipitation or DEAE filter assay with the same ligand. As for membrane-bound receptor, the detergent-solubilized levamisole receptor consists of more than one affinity state. Detergent solubilization appears to increase the affinity of all states for [3H]MAL (Kd for the highest affinity solubilized [3H]MAL binding state, 41 +/- 5 pM). Data is presented on the equilibrium binding and the association and dissociation reaction rates of the receptor. The similar relative efficacy with which various compounds inhibit specific [3H]MAL binding and deficiencies in solubilizable high affinity specific [3H]MAL binding in two receptor mutants show that the solubilized receptor is the same nicotinic acetylcholine receptor that is detected by assaying membrane-bound specific [3H]MAL binding. The detergent-solubilized levamisole receptor is stable at 0 degree to 4 degrees C, making receptor purification feasible.

A review of chest physiotherapy in neonatal intensive care units in Australia

Clinical techniques and protocols for chest physiotherapy vary greatly from one Neonatal Intensive Care Unit to another. In 1988 a questionnaire designed to investigate differing techniques used was distributed to Neonatal Intensive Care Units (NICU) around Australia. Fourteen of the 15 questionnaires were completed and returned. The results revealed that the methods of chest treatment and the indicators for commencing chest treatment were similar throughout NICU. Both physiotherapists and nursing staff played a role in the performance of chest treatment in all but one unit where it was the responsibility of nursing staff. However, the area in which there was most variability between NICU was the individual treatment protocols employed pre- and postextubation of the neonate. A review of literature over the past 10 years also demonstrates variability in chest physiotherapy. It was concluded that further well-controlled studies with larger sample sizes are needed to validate the use of chest physiotherapy for the neonate, especially in relation to the techniques and specific protocols employed.

Computer simulation for the prediction of separation as a function of pH for reversed-phase high-performance liquid chromatography. II. Resolution as a function of simultaneous change in pH and solvent strength

The optimization of reversed-phase high-performance liquid chromatographic separation by the simultaneous variation of pH and solvent strength (%B) was studied for acidic (substituted benzoic acids) and basic samples (substituted anilines). The combination of these two variables was expected to be more useful than either variable alone. This proved to be the case for the benzoic acid sample, but not for the aniline sample. Column plate numbers were also studied for each sample and as a function of pH. With the exception of one compound (3,5-dimethylaniline) in one particular pH range (3.0-4.5), plate numbers of 12,000-20,000 were observed for each sample.

Computer simulation for the prediction of separation as a function of pH for reversed-phase high-performance liquid chromatography. I. Accuracy of a theory-based model

Computer simulation software (DryLab I/mp) is described for predicting high-performance liquid chromatographic separation as a function of changes in mobile phase pH. Three experimental runs with pH (only) varied are used to derive values of pKa plus capacity factors (k') for the ionized and non-ionized form of each ionizable solute. Various tests of the experimental data then allow classification of each solute as acidic, basic, neutral (including strong or weak acids or bases) and amphoteric. Experimental data are reported for the separation of several substituted anilines as a function of pH and solvent composition (%B). Experimental requirements for the accurate prediction of separation (ca. +/- 2-4% in alpha) as a function of pH are discussed. The reliability of the software is demonstrated for three different samples: mixtures of (a) substituted benzoic acids, (b) substituted anilines and (c) catecholamine-related compounds.

Protein starvation impairs the ability of activated lymphocytes to produce interferon-gamma

The impairment of lymphocyte function in nutritionally deprived rats was studied. Lymphocytes from rats fed a diet lacking protein showed a severe decrease in their ability to proliferate when stimulated with mitogens. This was accompanied by a dramatic inhibition of interferon-gamma (IFN-gamma) production and a lesser decrease in the release of interleukin-2 (IL-2). Analysis of RNA levels by Northern blot hybridization confirmed that lymphocytes from protein-starved rats had lower levels of mRNAs for IFN-gamma, IL-2, and IL-2 receptor than those from control animals. Protein deprivation therefore leads to a modification of lymphocyte function such that IFN-gamma production in particular is severely impaired.

Safety profile and immunogenicity of an inactivated vaccine derived from an attenuated strain of hepatitis A

To determine the safety and immunogenicity of an inactivated hepatitis A vaccine, 56 healthy adult volunteers were randomly assigned to receive an intramuscular injection of 6.3, 12.5 or 25 ng of inactivated hepatitis A vaccine or placebo at 0, 2 or 4, and 24 weeks. Adverse reactions occurred with similar frequency in vaccine and placebo recipients and consisted primarily of pain or tenderness at the injection site. By 4 weeks after a single 6.3, 12.5 or 25 ng injection, seven, nine and ten out of ten vaccinees, respectively, had antibody detectable by a HAV AB assay modified to increase its sensitivity tenfold. All vaccinees had antibodies detectable by this assay within 2 weeks of their second inoculation. Geometric mean antibody levels increased with higher doses of vaccine (p = 0.05). Neutralizing antibody was detected within 4 weeks of a single inoculation in all vaccinees. Neutralizing antibody was detected after the third inoculation at dilutions of greater than or equal to 1:2048 in all 12.5 and 25 ng vaccinees. All 19 vaccinees tested at 24 months still had HAV antibodies detectable by a modified HAV AB assay. This inactivated hepatitis A vaccine appears to be well tolerated and immunogenic at doses of 6.3-25 ng. The choice of dose and vaccination schedule may depend on the rapidity with which seroconversion is desired.

The analysis of failure time data in crossover studies

Clinical trials of new drugs in the treatment of angina pectoris frequently make use of exercise tests to evaluate efficacy. The crossover design is often employed. The methods commonly used to analyse the various exercise times, for example, 'time to pain', are insensitive and potentially biased by the manner in which they deal with the censored nature of the data. Survival analysis can be adapted for use in crossover trials, both in a relatively simple way, and also through the full power of the Cox model. This is considerably more sensitive and not subject to the same bias. This methodology leads to the use of median survival times to illustrate treatment effects and this provides a practical interpretation of clinical relevance. The estimation of median survival times in crossover trials poses some special problems. The methodology is illustrated throughout by means of a specific two-period example in which atenolol was compared with the combination of atenolol and nifedipine. The three-period design is also briefly discussed.

Three-point versus two-point method for early individualization of aminoglycoside doses

An approach using two serum concentrations following the initial dose of an aminoglycoside was retrospectively evaluated using the first and third samples from all three-point studies conducted by the pharmacokinetic consult service in 1988. The same Sawchuk and Zaske method was used for the three-point and two-point studies. Although the predicted peaks and troughs from the two-point study were statistically different from those of the three-point study, it is the authors' opinion that the root mean squared error of 0.38 mg/L (95% confidence interval [CI] 0.31-0.45) for the peaks and 0.09 mg/L (95% CI 0.06-0.11) for troughs is well within the limits of acceptable clinical error for gentamicin and tobramycin. Eliminating one-third of initial aminoglycoside concentrations could result in significant time and cost savings.

Interferon selectively inhibits the expression of mitochondrial genes: a novel pathway for interferon-mediated responses

As an approach to identifying genes involved in physiological actions of interferons we used differential probes to screen a cDNA library from mouse L-929 cells treated with interferon alpha/beta. We identified two negatively regulated mRNA species which have been examined by analysis of the corresponding mRNAs and by DNA sequencing. Comparison with the GenBank database showed that these cDNA clones corresponded to mitochondrially encoded genes for cytochrome b and subunit I of cytochrome c oxidase. A further cDNA encompassing three mitochondrial genes was used as a probe to show that a third mRNA, NADH dehydrogenase subunit 5, was also down-regulated by interferon while a fourth, NADH dehydrogenase subunit 6, was unaffected. Expression of cytochrome b was also inhibited in mouse NIH 3T3 cells treated with interferon alpha/beta and in human Daudi lymphoblastoid cells treated with interferon alpha. The ability of interferon to reduce mitochondrial mRNA levels could be blocked by cycloheximide suggesting that these effects are mediated by an interferon-responsive nuclear gene which encodes a product capable of regulating mitochondrial gene expression. Analysis of proteins synthesized in the presence of emetine, a specific inhibitor of cytoplasmic translation, showed that the synthesis of several mitochondrial translation products, including cytochrome b, was reduced after treatment with interferon. Our results reveal a novel effect of interferon on cellular physiology which could have important consequences for understanding the effects of interferons as well as suggesting new mechanisms for the regulation of mitochondrial biogenesis and function.

Conserved sequence and structural elements in the HIV-1 principal neutralizing determinant

The principal neutralizing determinant (PND) of human immunodeficiency virus HIV-1 is part of a disulfide bridged loop in the third variable region of the external envelope protein, gp120. Analysis of the amino acid sequences of this domain from 245 different HIV-1 isolates revealed that the PND is less variable than thought originally. Conservation to better than 80 percent of the amino acids in 9 out of 14 positions in the central portion of the PND and the occurrence of particular oligopeptide sequences in a majority of the isolates suggest that there are constraints on PND variability. One constraining influence may be the structural motif (beta strand--type II beta turn--beta strand--alpha helix) predicted for the consensus PND sequence by a neural network approach. Isolates with a PND similar to the commonly investigated human T cell lymphoma virus IIIB (HTLV-IIIB) and LAV-1 (BRU) strains were rare, and only 14 percent of sera from 86 randomly selected HIV-1 seropositive donors contained antibodies that recognized the PND of these virus isolates. In contrast, over 65 percent of these sera reacted with peptides containing more common PND sequences. These results suggest that HIV vaccine immunogens chosen because of their similarity to the consensus PND sequence and structure are likely to induce antibodies that neutralize a majority of HIV-1 isolates.

Antibody-mediated in vitro neutralization of human immunodeficiency virus type 1 abolishes infectivity for chimpanzees

This study was undertaken to establish whether antibody directed against the human immunodeficiency virus type 1 (HIV-1) principal gp120 type-specific neutralization determinant can abolish the infectivity of HIV-1 in chimpanzees. Challenge inocula of the IIIb virus isolate were mixed in vitro with either immunoglobulin G (IgG) from an uninfected chimpanzee, nonneutralizing IgG from an HIV-seropositive human, a virus-neutralizing murine monoclonal antibody directed against the HIV-1 IIIb isolate, or virus-neutralizing IgG from a chimpanzee infected with the IIIb isolate. Both neutralizing antibodies were directed against the principal neutralization determinant of the challenge isolate. Establishment of infection following inoculation of each virus-antibody mixture into chimpanzees was assessed by virus-specific antibody development and by virus isolation. No protective effect was noted either with the control IgG or with the nonneutralizing anti-HIV IgG. By contrast, the polyclonal chimpanzee virus-neutralizing IgG prevented HIV-1 in vivo infection, while the neutralizing monoclonal antibody notably decreased the infectivity of the challenge virus. Hence, antibody to the gp120 principal neutralization determinant is able both to prevent HIV-1 infection in vitro and to inhibit infection in vivo.

Meta-analysis of value of propranolol in prevention of variceal haemorrhage

A meta-analysis of all controlled clinical trials of beta-adrenoceptor blocking drugs, principally propranolol, in the prevention of primary or secondary variceal bleeding has shown that beta-blockade significantly reduced the occurrence of variceal bleeding, deaths from variceal bleeding, and overall mortality. There was some heterogeneity between trials in the effect of beta blockade on secondary prevention. When only fully reported, randomised, placebo-controlled studies were included the heterogeneity disappeared, and the reductions in bleeding episodes and mortality became more striking. Separate analyses of primary and secondary prevention studies also showed clear reductions in occurrence of variceal bleeding and deaths. These results seem to indicate the value of beta-adrenoreceptor blocking drugs for the primary prevention of haemorrhage from large oesophageal varices. However, there is still a need for large multicentre trials of beta-blockade for primary prevention of variceal bleeding in patients without large varices and of comparisons between beta-blocker therapy with other treatments in secondary prevention.

Beta and gamma interferons act synergistically to produce an antiviral state in cells resistant to both interferons individually

We showed previously that the mouse fibroblastoid cell line Ltk-aprt- is resistant to the antiviral effects of beta interferon. This lack of response reflects a partial sensitivity to the interferon that is accompanied by a failure to activate expression of several interferon-regulated genes, although certain other genes respond in a normal manner. We show here that Ltk-aprt- cells were also unable to establish an antiviral state and to activate expression of 2,5-oligo(A) synthetase when treated with gamma interferon. Strikingly, however, treatment with a combination of beta interferon and gamma interferon provided complete protection against viral replication. Although the cells were completely insensitive to up to 250 U of the interferons per ml added singly, essentially complete protection from viral cytopathic effects was achieved when as little as 10 U of each of the interferons per ml were combined. Expression of 2,5-oligo(A) synthetase was also sensitive to this synergistic effect. Activation of an antiviral state could also be achieved by sequential treatment, first with gamma interferon and then with beta interferon. Partial protection against viral replication could be achieved by pretreatment with gamma interferon for as little as 1 h before incubation with beta interferon and could be blocked by the addition of specific antibodies or by cycloheximide, indicating that gamma interferon induces the synthesis of a protein which can act synergistically with a signal produced by the beta-interferon receptor. We suggest that Ltk-aprt- cells suffer from defects in one or more components of the gene activation pathways for both type I and type II interferons. Nonetheless, gamma interferon is able to activate the expression of a gene encoding a protein required for signal transduction. This protein acts synergistically with a transient signal produced in response to beta interferon, thereby activating the expression of a further group of genes.