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Biomedical subjects

P Hauser

Publications and source records attributed to P Hauser.

At least 55 records · Page 3Linked to original sources
PubMed1995

Nonresponders to hepatitis B vaccine can present envelope particles to T lymphocytes.

The mechanisms causing nonresponsiveness to hepatitis B surface Ag (HBsAg) vaccines in humans remain largely unknown. The increased incidence of nonresponsiveness in subjects with HLA-DR3 or -DR7 haplotype suggests that immune response mechanisms governed by genes of the MHC are involved. It is conceivable that APC of nonresponders are defective in the presentation of HBsAg because they are unable to adequately take up, process, or present this Ag. To examine this hypothesis we have used PBMC from nonresponders to present recombinant particles containing S or PreS2-S sequences to HBsAg-specific T cell lines from haplo-identical responder vaccinees. The proliferative response of these lines was used to evaluate the efficacy of Ag presentation. Unfractionated PBMC from five DR2+ and six DR7+ nonresponders did not proliferate to HBsAg in vitro, whereas they vigorously proliferated upon stimulation with tetanus toxoid, thus ruling out the presence of a generalized immunodeficiency. All DR2(15)+ nonresponders were able to present hepatitis B envelope Ag to HBsAg-specific, DR1501-restricted T cells. PBMC from six DR7+ nonresponders were all able to present HBsAg to DR07-restricted T cell lines and PBMC from three DPw4+ nonresponders were able to present HBsAg to DP0402-restricted T cell lines. Additional experiments showed that PBMC from two nonresponders presented HBsAg equally well and sometimes better than PBMC from two partially HLA-matched high responders. We conclude that HLA-DR2+, -DR7+, and -DPw4+ nonresponder vaccinees are able to take up, process and present HBsAg to allogeneic, haplo-identical T cell lines in vitro.

Adult↗
PubMed1995

The Lyme disease vaccine candidate outer surface protein A (OspA) in a formulation compatible with human use protects mice against natural tick transmission of B. burgdorferi.

Development of a vaccine for the Lyme disease spirochete, Borrelia burgdorferi, has focused on the bacterial lipoprotein, major outer surface protein A (OspA). With few exceptions, testing of OspA vaccines in animal models has involved challenge with needle inoculation of cultured spirochetes. Recombinant OspA proteins from two OspA divergent strains of B. burgdorferi were tested for their vaccine potential in three different strains of mice challenged with laboratory reared ticks with a high rate of B. burgdorferi infection. All formulations of the B. burgdorferi sensu stricto derived OspA vaccine protected all strains of mice when challenged by ticks infected with an OspA homologous strain of the spirochete, whereas heterologous OspA from B. afzelii did not protect. Furthermore, ticks feeding on protected mice had reduced OspA levels compared to unvaccinated controls.

Animals↗
PubMed1995

T2 hyperintensities in bipolar disorder: magnetic resonance imaging comparison and literature meta-analysis.

OBJECTIVE: Accumulating evidence suggests a greater number of T2 abnormalities in the brains of patients with bipolar I disorder. The authors sought to evaluate the presence of signal "hyperintensities" in both bipolar I and II subjects and systematically review the existing literature. METHOD: Magnetic resonance images of the brain were obtained prospectively for 29 patients with bipolar I disorder, 26 patients with bipolar II disorder, and 20 normal comparison subjects. The presence and location of signal hyperintensities in three brain regions (periventricular white matter, subcortical gray matter, and deep white matter) were evaluated. RESULTS: No significant differences were found between groups for the presence of subcortical gray or deep white matter hyperintensities. Periventricular hyperintensities were more common in bipolar I patients (62%) than in bipolar II patients (38%) and normal comparison subjects (30%). Within patient groups, medication use was not significantly different for those with or without the presence of white matter hyperintensities. The literature on bipolar disorder and signal hyperintensities is reviewed. A meta-analysis of the pooled data in the literature on bipolar illness and signal hyperintensities revealed that the odds of having a T2 hyperintensity are significantly greater for bipolar I than for normal comparison subjects. CONCLUSIONS: Having bipolar I disorder significantly increases the chance of having white matter changes in the brain. This study suggests that bipolar II patients may be more similar than bipolar I patients to comparison subjects on T2 measures. The possible pathophysiological significance of hyperintensities is discussed.

Adult↗
PubMed1994

Immunization of mice by recombinant OspA preparations and protection against Borrelia burgdorferi infection induced by Ixodes ricinus tick bites.

The wide distribution of Borrelia burgdorferi, the spirochete causing Lyme borreliosis, represents a human health hazard in many areas of the world. Vaccination has been proposed as an effective prevention strategy. Vaccination experiments were conducted with preparations of recombinant outer surface protein A (OspA) derived from Borrelia burgdorferi strain ZS7. Mice received three doses (1 microgram each) of the antigens adsorbed to aluminum hydroxide. A strong immune response to the vaccine antigen was observed. Mice were challenged after immunization, using Ixodes ricinus nymphal ticks infected with Borrelia burgdorferi strain ZS7. Infection was investigated by ear biopsy culture, xenodiagnosis with uninfected larvae and serological response to Borrelia burgdorferi antigens. All unimmunized control animals were found to be infected, while all immunized animals were found to be protected against infection by Borrelia burgdorferi. In addition, most adult ticks derived from nymphs that fed on immunized mice were found to be free of spirochetes.

Animals↗
PubMed1994

Correlation between in vivo humoral and in vitro cellular immune responses following immunization with hepatitis B surface antigen (HBsAg) vaccines.

To study the regulation of the human immune response to hepatitis B surface antigen (HBsAg) we have carefully monitored the in vivo humoral and in vitro cellular immune responses to HBsAg in 50 subjects receiving four doses of hepatitis B vaccine according to a 0, 1, 2, 12 month vaccination scheme. Twenty-three subjects were given a plasma-derived vaccine (Hevac B) and 27 received a recombinant HBsAg vaccine (yeast-derived; Engerix-B). The humoral and cellular immune responses were measured before vaccination (day 0); 6 days after the second dose (day 36); 6 days (day 66), 2 months (day 120) and 10 months (day 365) after the third dose and 1 month after the fourth dose (day 395). Based on the kinetics of the humoral immune responses, the vaccinees could be classified into fast, intermediate and slow/non-responders. Based on the magnitude of the immune response (anti-HBs titre) on day 395, the vaccinees could be divided into high (> or = 2000 U l-1) and low (< or = 2000 U l-1) responders. A close correlation between the kinetics and the magnitude of the humoral immune response was observed. The in vivo anti-HBs response was measured using commercially available immunoradiometric assays. The in vitro cellular immune response was measured using an HBsAg-specific lymphoproliferation assay. Because of interassay variability the results were considered as dichotomous variables (proliferation versus non-proliferation) for further data analysis. A statistically significant correlation was observed between the kinetics and magnitude of the humoral immune response on the one hand and the in vitro anti-HBs response on the other hand.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1993

Attention deficit-hyperactivity disorder in people with generalized resistance to thyroid hormone.

BACKGROUND: Attention deficit-hyperactivity disorder is a well-recognized psychiatric disorder of childhood. Its cause is unknown, but there is evidence of a familial predisposition. Symptoms suggestive of this disorder have been reported in subjects with generalized resistance to thyroid hormone, a disease caused by mutations in the thyroid receptor-beta gene and characterized by reduced responsiveness of peripheral and pituitary tissues to the actions of thyroid hormone. We systematically evaluated the presence and severity of attention deficit-hyperactivity disorder in 18 families with a history of generalized resistance to thyroid hormone. METHODS: We studied 49 affected and 55 unaffected family members; 52 were adults, and 52 were children. All subjects were evaluated with structured psychiatric questionnaires by interviewers who were unaware of the medical diagnosis. The number of symptoms of attention deficit-hyperactivity disorder was calculated for each subject. RESULTS: Among the adults, 11 of 22 subjects with generalized resistance to thyroid hormone (50 percent) and 2 of 30 unaffected subjects (7 percent) had met the criteria for attention deficit-hyperactivity disorder as children (P < 0.001). Among the children, 19 of 27 subjects resistant to thyroid hormone (70 percent) and 5 of 25 unaffected subjects (20 percent) met the criteria for the disorder (P < 0.001). The odds of having attention deficit-hyperactivity disorder were 3.2 times higher for affected male subjects than for affected female subjects and were 2.7 times higher for unaffected male subjects than for unaffected female subjects. The mean symptom score was 2.5 times higher in the affected group than in the unaffected group (7.0 vs. 2.8, P < 0.001). The frequency of other psychiatric diagnoses was similar in the two groups. CONCLUSIONS: In our study sample, attention deficit-hyperactivity disorder is strongly associated with generalized resistance to thyroid hormone.

Adult↗
PubMed1993

Site-specific alterations in the B oligomer that affect receptor-binding activities and mitogenicity of pertussis toxin.

Pertussis toxin plays a major role in the pathogenesis of whooping cough and is considered an important constituent of vaccines against this disease. It is composed of five different subunits associated in a molar ratio 1S1:1S2:1S3:2S4:1S5. The S1 subunit is responsible for the ADP-ribosyltransferase activity of the toxin. The B moiety, composed of S2 through S5, recognizes and binds to the target cell receptors and has some ADP-ribosyltransferase-independent activities such as mitogenicity. Site-directed mutagenesis of subunits S2 and S3 allowed us to identify amino acid residues involved in receptor binding. Of all the modifications generated, the deletion of Asn 105 in S2 and of Lys 105 in S3 resulted in the more drastic reduction of binding to haptoglobin and CHO cells, respectively. A holotoxin carrying both deletions presented a mitogenicity reduced to an undetectable level. The combination of these B oligomer mutations with two substitutions in the S1 subunit led to the production of a toxin analog with reduced ADP-ribosyltransferase-dependent and -independent activities including mitogenicity. As shown by immunoprecipitation with various monoclonal antibodies, the mutant holotoxin was correctly assembled and antigenically similar to the native toxin. This toxin analog induced toxin-neutralizing antibodies at the same level as the holotoxin carrying only mutations in the S1 subunit, and may therefore be considered a useful candidate for the development of a new generation vaccine against whooping cough.

ADP Ribose Transferases↗
PubMed1993

Haptoglobin polymorphism and the immune response after hepatitis B vaccination.

One hundred healthy Caucasian medical students (age 22 +/- 1 years) were vaccinated with a recombinant hepatitis B vaccine and their haptoglobin types were determined. A relationship between haptoglobin type and immune response to the vaccine was observed. Subjects with a 2-2 haptoglobin phenotype produced significantly lower hepatitis B antibody titres than those having a 1-1 or 2-1 haptoglobin phenotype. The haptoglobin phenotypes not only influenced the magnitude but also the kinetics of the anti-HBs response. For all haptoglobin types, haptoglobin concentration and immune response to the vaccine behaved independently.

Adult↗
PubMed1993

Characterization of the immune response of volunteers vaccinated with a killed vaccine against hepatitis A.

To characterize the immune response elicited by the hepatitis A virus (HAV) vaccine, the sera of 79 subjects who received two vaccine doses at an interval of 1 month and a booster dose 6 months after the first dose, were analysed by ELISA, radioimmunofocus inhibition test (RIFIT) and by a competition monoclonal antibody assay using two neutralizing mAbs (K3-4C8 and B5-B3), which recognize different epitopes. The data show that 93.6% of the volunteers responded after one dose, as detected by ELISA. After the second dose, 100% seroconversion (total Ig) was achieved and most of the vaccines had neutralizing antibodies. Furthermore, these antibodies are able to inhibit the binding of mAbs K3-4C8 and B5-B3 to the HAV virus, indicating that they recognize two major neutralizing epitopes identified on infectious virions. Using a standard commercial radioimmunoassay test, 100% of the subjects were found positive after the third dose. These different methods of titration were also performed on sera of convalescents and immune serum globulin (ISG) recipients. Although the level of antibodies in convalescents is significantly higher than in vaccinees or in ISG recipients, the relative amount of neutralizing antibodies quantified by the competition monoclonal antibody assay is equivalent for the groups tested.

Adolescent↗
PubMed1993

Role of SV40 T antigen binding to pRB and p53 in multistep transformation in vitro of human uroepithelial cells.

In the present study, we examined the sufficiency of SV40 T antigen (Tag) binding to pRB and p53 to substitute for alterations in RB and TP53 at all stages of human uroepithelial cell (HUC) transformation in vitro. Two independent SV40 immortalized HUCs (SV-HUC and SV-HUC/CK2) and 17 independent derivative carcinogen-induced or spontaneous tumors (T-SV-HUCs and T-SV-HUC/CK2) representing different stages of urothelial tumorigenesis were examined. Although five of 17 T-SV-HUCs and SV-HUC/CK2 and its derivative tumor showed 13q chromosome deletion and loss of heterozygosity (LOH), this did not reflect functional loss of pRB because Tag/pRB binding was unaltered and sequencing showed a normal RB gene in all these tumors. No genetic alterations involving 17p or TP53 were detected in any tumors in this study using the same techniques. These results indicate that Tag/pRB and Tag/p53 binding apparently abrogate requirements for/or a selective advantage of RB and TP53 mutations in HUC tumorigenic transformation and progression, as well as in HUC immortalization. These data also provide new evidence that more than one suppressor gene may be located on chromosome 13q.

Antigens, Polyomavirus Transforming↗
PubMed1993

Simian virus 40 (SV40) T-antigen mutations in tumorigenic transformation of SV40-immortalized human uroepithelial cells.

pSV2Neo, a plasmid that contains the wild-type simian virus 40 (SV40) origin of replication (ori), is widely used in mammalian cell transfection experiments. We observed that pSV2Neo transforms two nontumorigenic SV40-immortalized human uroepithelial cell lines (SV-HUC and CK/SV-HUC2) to G418 resistance (G418r) at a frequency lower than that at which it transforms SV-HUC tumorigenic derivatives (T-SV-HUC). Transient expression studies with the chloramphenicol transferase assay showed that these differences could not be explained by differences in Neo gene expression. However, when we replaced the SV40 ori in pSV2Neo with a replication-defective ori to generate G13.1Neo and G13.1'Neo, the G418r transformation frequency of the SV40-immortalized cell lines was elevated. Because SV40 T antigen stimulates replication at its ori, we tested plasmid replication in these transfected cell lines. The immortalized cell lines that showed low G418r transformation frequencies after transfection with pSV2Neo showed high levels of plasmid replication, while the T-SV-HUC that showed high G418r transformation frequencies failed to replicate pSV2Neo. To determine whether differences in the status of the T-antigen gene contributed to the phenomenon, we characterized the T-antigen gene in these cell lines. The results showed that the T-SV-HUC had sustained mutations in the T-antigen gene that would interfere with the ability of the T antigen to stimulate replication at its ori. Most T-SV-HUC contained a super-T-antigen replication-defective ori that apparently resulted from the partial duplication of SV40 early genes, but one T-SV-HUC had a point mutation in the ori DNA-binding domain of the T-antigen gene. These results correlate with the high G418r transformation frequencies with pSV2Neo in T-SV-HUC compared with SV-HUC and CK/SV-HUC2. Furthermore, these results suggest that alterations in SV40 T antigen may be important in stabilizing human cells immortalized by SV40 genes that contain the wild-type SV40 ori, thus contributing to tumorigenic transformation. This is the first report of a super T antigen occurring in human SV40-transformed cells.

Antigens, Polyomavirus Transforming↗
PubMed1993

Differential expression of mutant and normal beta T3 receptor alleles in kindreds with generalized resistance to thyroid hormone.

Thyroid hormone resistance (THR) is primarily an autosomal dominant inherited disease characterized by resistance of pituitary and peripheral tissues to the action of thyroid hormone. We investigated whether the heterogeneous phenotypic features that occur not only among kindreds but also within the same kindred might be due to the expression of differing ratios of mutant and normal receptors in tissues. Using an allele-specific primer extension method, we determined the relative expression of normal and mutant mRNAs from the fibroblasts of affected and unaffected members of two kindreds with TRH: A-H and N-N. While two affected members of A-H, as expected, had nearly equal amounts of normal and mutant hTR beta mRNA, two other members had mutant mRNA levels that accounted for at least 70% of the hTR beta mRNA. Phenotypic variability within and between kindreds with generalized resistance to thyroid hormone GRTH may be due to this differential expression of the mutant and wild type mRNA. Furthermore, when several clinical parameters of THR were compared in several affected members from two kindreds with GRTH, we found that two cases in one kindred exhibited a high mutant-to-normal hTR beta ratio and had considerably more bone resistance during their development. In certain kindreds with THR, differing ratios of normal and mutant hTR receptors may be age and growth related and may account for the reported attenuation of phenotypic symptoms with age.

Adolescent↗