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H Pfister

Publications and source records attributed to H Pfister.

At least 73 records · Page 4Linked to original sources
PubMed1998

Point mutations in SP1 motifs in the upstream regulatory region of human papillomavirus type 18 isolates from cervical cancers increase promoter activity.

Evidence of the functional significance of two naturally occurring mutations at nt 40 or 41 in the Sp1 motif in the promoter proximal segment of the upstream regulatory region (URR) of human papillomavirus (HPV) type 18 is presented. In electrophoretic mobility shift assays, Sp1 protein bound more efficiently to the Sp1 mutant motifs than to the prototype; while in both HeLa and HT3 cells, luciferase activity controlled by the mutant URRs was upregulated 2- and 3-fold, or 4- and 6-fold, in comparison with the prototype URR or HeLa cell-derived URR respectively. The HeLa URR represents a more appropriate baseline for promoter activity, containing a series of point mutations representative of most HPV-18 cancer isolates, including one in the Yin Yang 1 (YY1) site at the P105 promoter. The effect of the Sp1 mutations was found to be largely maintained in the context of the HeLa URR containing the prototype YY1 site.

Alanine↗
PubMed1998

Structure, content and reliability of the Munich-Composite International Diagnostic Interview (M-CIDI) substance use sections.

After reviewing currently available diagnostic assessment instruments for substance use disorders this paper describes the format and structure of the Munich-Composite International Diagnostic Interview (M-CIDI) substance disorder section. In addition, the test-retest reliability of diagnoses and criteria for nicotine, alcohol, illegal and prescription drugs, is reported. Findings obtained in community sample of adolescents and young adults indicate that the substance section is acceptable for almost all types of respondents, efficient in terms of time and ease of administration as well as reliable in terms of consistency of findings over time. The test-retest reliability over a period of an average of 1 month, as examined by two independent interviewers indicates good-to-excellent kappa values for all substance disorders assessed, with significant kappa values ranging between 0.55 for drug abuse and 0.83 for alcohol abuse. There was also fairly consistently high agreement for the assessment of single DSM-IV diagnostic criteria for abuse and dependence as well as the M-CIDI quantity-frequency and time-related questions. To conclude, although - unlike previous studies - this study was conducted in a community sample and not in patients and used considerably longer time intervals of more than a month between investigations, our M-CIDI reliability findings are at least as high as those from previous studies.

Adolescent↗
PubMed1998

Use, abuse and dependence of prescription drugs in adolescents and young adults.

Lifetime prevalence estimates of psychotropic medicine use as well as prevalence of DSM-IV prescription drug use disorders from the baseline investigation of the Early Developmental Stages of Psychopathology (EDSP) Study are presented. Use of prescription medication at some time in their life was reported by 27.4% of the respondents. Illicit use of prescription drugs, which means an intake without medical legitimation, was reported by 4.5% of the sample. The findings suggest that abuse of and dependence on prescription drugs, with most cases reporting polysubstance use, is quite rare in the 14- to 24-year-olds. DSM-IV abuse was more prevalent than dependence (0.5 vs. 0.3%). In general, women reported higher prevalence rates of prescription drug use, whereas men reported higher prevalence rates of prescription drug disorders. This result suggests that men have a higher risk to develop a substance-use-related disorder.

Adolescent↗
PubMed1998

Interaction of human papillomavirus 8 regulatory proteins E2, E6 and E7 with components of the TFIID complex.

Human papillomavirus 8 (HPV8) is one of the oncogenic HPV types specifically associated with skin cancers of epidermodysplasia verruciformis patients. The early gene products of this virus exert functions in transformation (E2, E6, E7), replication (E1, E2) and in the control of viral transcription (E2, E7). Many viral and cellular transactivators of transcription have been shown to interact selectively and directly with a number of TATA-box-binding protein (TBP)-associated factors (TAFIIs), which then play a role as coactivators. Using glutathione-S-transferase (GST) pull-down experiments, we tested in vitro interactions between GST-HPV8-E1, -E2, -E6 and -E7 and 7 in-vitro-translated TAFIIs in the human (h) system (hTAFII18, hTAFII20, hTAFII28, hTAFII30, hTAFII55, hTAFII100, hTAFIIDeltaN135) or TBP. We could show that GST-HPV8-E2 interacts directly at least with hTAFII55 and TBP. Deletion analysis indicated that a domain overlapping with the C-terminal moiety of HPV8-E2 is required for binding to TBP, whereas determinants for interactions with hTAFII55 are in the central and C-terminal part of the E2 protein. In similar binding studies, GST-HPV8-E6 interacted with hTAFII28, hTAFIIDeltaN135 and TBP, and more weakly with hTAFII20, whereas GST- HPV8-E7 bound to hTAFII20, hTAFII28, hTAFII55, hTAFIIDeltaN135 and TBP. Deletion analysis revealed that the C-terminal part of HPV8-E7 is required for the interaction with these hTAFIIs. In contrast, no interactions were observed between GST-HPV8-E1 and in-vitro-translated hTAFIIs.

Binding Sites↗
PubMed1998

[YY1 and its repressive effect on human papillomavirus 16 early promoter P97 existed widely among human epithelial cell lines].

Cellular transcription factor YY1 represses the activity of early promoter P97 of HPV 16. Removal of the specific binding sites for YY1 in HPV 16 LCR can increase the P97 activity. To analyse the expression of YY1 and the existence of the activation effect on P97 due to removing YY1 binding sites in the LCR region, we extracted nuclear proteins from four cervical cancer cell lines and two human keratinocytes. EMSA assays were carried out in vitro. At the same time, we transiently transfected the luciferase reporter plasmids, which contain HPV 16 reference and mutated LCR sequences, respectively, into the different cells and determined the luciferase expressions. The results showed that all the analysed cell lines contained biologically functional YY1 proteins. No remarkable difference in the concentration of native YY1 proteins could be detected among the tested cells. Removal of YY1 binding sites in HPV 16 LCR could elevate P97 activity in several analysed cell lines, including normal human primary kerationcytes from foreskin. It suggests that YY1 regulatory system exists widely in human epithelial cell lines. We also found that the transcription activator NF1 was more highly expressed in C33a cell than in HT3 cell, indicating an unevenly distribution of functional proteins in various cell lines.

Cells, Cultured↗
PubMed1997

Virological treatment failure of protease inhibitor therapy in an unselected cohort of HIV-infected patients.

OBJECTIVE: To determine the rate of virological treatment failure with protease inhibitor therapy in unselected patients and to assess underlying risk factors. DESIGN AND SETTING: Retrospective study in two German tertiary care treatment centres. PATIENTS: A total of 198 HIV-infected patients treated with protease inhibitors in 1996. MAIN OUTCOME MEASURES: Levels of HIV RNA 1-6 months after start of treatment; definition of treatment failure of < 1 log10 reduction in plasma HIV RNA within 6 months after starting protease inhibitor therapy; multivariate analysis of risk factors for treatment failures. RESULTS: A total of 226 treatment episodes with protease inhibitors were evaluable (saquinavir, 83; ritonavir, 47; indinavir, 96). The rate of virological treatment failure was 44% (saquinavir, 64%; ritonavir, 38%; indinavir, 30%). In a multivariate analysis, the following independent risk factors for virological failure were found: CD4 cell count, pretreatment with antiretroviral drugs (number), and protease inhibitor (compound). The relative risk reduction for each CD4 cell count increase was 0.997 (P = 0.012), 2.64 for pretreatment with one or two drugs versus no drug (P = 0.05), 2.97 for pretreatment with more than two drugs versus no drug (P = 0.05), and 4.62 for treatment with saquinavir versus indinavir (P = 0.001). CONCLUSION: An unexpectedly high rate of virological treatment failure of protease inhibitor therapy was found in an unselected cohort of HIV-infected patients. Response to antiretroviral combination therapy in normal clinical practice may considerably differ from results of randomized clinical trials. Further studies are warranted to find optimal treatment strategies for both initial and salvage therapy.

Adult↗
PubMed1997

Sequence variation in the upstream regulatory region of HPV 18 isolates from cervical cancers.

This study describes sequence variation in both the enhancer and promoter segments of the upstream regulatory region (URR) of 28 human papillomavirus (HPV) type 18 isolates from cervical cancers, 25 from women treated at an Australian center and three from overseas included for comparison. No large-scale changes were found in either region. Fourteen substitutions were identified in the enhancer region with the number in individual isolates ranging from one to eight. Four substitutions impacted cellular transcription factor binding sites but there were no obvious associations with clinicopathological variables. The promoter segment was found to be more highly conserved than the enhancer, but four of the five point mutations identified involved cellular transcription factor binding motifs including a substitution of C for T at nt 104 which affected 21 samples. This change was found to impact upon a previously unrecognized Yin Yang (YY1) binding site. Electrophoretic mobility shift assays (EMSA) showed that this substitution significantly reduced protein-DNA binding and evidence was sought for its possible clinical implications. Of the 24 women with less than Stage III disease and known clinical outcome, tumor recurrence was observed in all of the 6 women whose isolates had the "prototype" T at nt 104, whereas only 8 of the 18 cancers with the mutation at this YY1 site recurred. This is the first report on URR variation in HPV 18 isolates from the South Pacific region. The study also provides initial data on diversity in the promoter region and preliminary evidence suggesting that a specific point mutation in this region may be clinically significant.

DNA, Viral↗
PubMed1997

Regulatory interactions of transcription factor YY1 with control sequences of the E6 promoter of human papillomavirus type 8.

Human papillomavirus type 8 (HPV-8) is a strictly cutaneous oncogenic virus known to induce malignant skin lesions in epidermodysplasia verruciformis patients. Our study shows that sequences surrounding transcription start sites of the HPV-8 oncogene E6 (nt 175-179) and comprising the presumable CCAAC and TATA boxes of the E6 promoter P175 contain a cluster of four motifs similar to the DNA recognition site of the multifunctional cellular transcription factor yin-yang 1 (YY1). Using DNase I footprinting and gel retardation tests it could be demonstrated that three of these motifs indeed act as YY1 binding sites. To test their functional relevance for P175 activity, engineered YY1 binding site mutants were analysed in the context of a P175 test vector using transient expression assays with human keratinocytes. YY1 turned out to exert both positive and negative effects upon the activity of the HPV-8 E6 promoter; binding of YY1 to a site upstream of the promoter's cap-position (BS1) activated transcription, whereas the downstream site (BS2) mediated repression. The second downstream YY1 binding site (BS3) seemed to play an auxiliary role, enhancing the negative effect of YY1 BS2. These observations define YY1 as an important cellular protein involved in the control of E6 oncogene expression of the skin-specific 'high risk' HPV-8 and emphasize the potential regulatory role of sequences located downstream of the transcription start site.

DNA-Binding Proteins↗
PubMed1997

Human papillomavirus DNA in non-melanoma skin cancers of a renal transplant recipient: detection of a new sequence related to epidermodysplasia verruciformis associated types.

The detection of human papillomavirus (HPV) types originally isolated from patients with epidermodysplasia verruciformis (EV) in skin tumors of transplant recipients may point to a role of this HPV subgroup in non-melanoma skin cancer in immunosuppressed people. We analyzed 17 formalin-fixed, paraffin-embedded biopsies of benign or malignant skin tumors of a renal transplant patient with unusually widespread cutaneous carcinomas. Using a nested polymerase chain reaction (PCR), HPV-specific DNA was demonstrated in 11 specimens (65%). Analysis of nine PCR amplification products revealed four different sequences related to EV-associated HPVs. Three sequences occurred only in one lesion. In six samples identical sequences were found that differed from all HPV sequences published to date and may therefore represent a novel EV-HPV type, preliminarily labeled RTRX7. RTRX7 was found in benign, premalignant, and malignant skin lesions. Alignments identified HPV12 as the closest relative of RTRX7, both in the DNA (81% homology) and in the amino acid sequence (84% homology).

Adult↗
PubMed1997

Comparison of inducible nitric oxide synthase expression in the brains of Listeria monocytogenes-infected cattle, sheep, and goats and in macrophages stimulated in vitro.

The expression of inducible nitric oxide synthase (iNOS) was studied in the brains of cattle, sheep, and goat that succumbed to a natural infection with Listeria monocytogenes. The lesions in infected brains are characterized by microabscesses, perivascular cuffs, gliosis, glial nodules, and large areas of malacia. Using immunocytochemistry, we detected bacteria in microabscesses, particularly in sheep and goats, and in areas without signs of inflammation, but not in perivascular infiltrates. iNOS was expressed by macrophage (Mphi)-type cells of microabscesses and glial nodules but rarely by Mphi in areas of malacia, as determined by immunohistochemistry with iNOS-specific antibodies. iNOS was not detected in perivascular cuffs. Major histocompatibility complex class II molecules (MHC-II), another marker of cell activation, showed a different pattern of distribution. Perivascular cuffs contained high numbers of MHC-II-positive cells, including some with Mphi characteristics. Microabscesses in sheep and goats showed low expression of MHC-II, particularly in iNOS-expressing cells. In cattle, the expression of markers for activated or recruited phagocytes, the calcium-binding proteins S100A8 and S100A9 (formerly called MRP-8 and MRP-14, respectively), was largely restricted to cells showing weak or undetectable iNOS expression; iNOS-positive Mphi showed a low expression of S100A8 and S100A9. Thus, iNOS is expressed by a restricted subset of Mphi in listeric encephalitis. In cultured sheep and goat Mphi, a low proportion of cells expressed iNOS upon activation by L. monocytogenes and gamma interferon, resulting in nitrite generation at least 1 order of magnitude lower than that in similarly treated cattle Mphi. Since these species differences were much less obvious in vivo, it appears that the well-known species variation in iNOS expression by Mphi could reflect an in vitro phenomenon.

Animals↗
PubMed1997

Serum factors, cell membrane CD14, and beta2 integrins are not required for activation of bovine macrophages by lipopolysaccharide.

The role of serum factors such as lipopolysaccharide (LPS)-binding protein (LBP) and of macrophage-expressed CD14 and beta2 integrins in the activation of bovine macrophages by LPS was investigated. Macrophage activation was determined by measuring tumor necrosis factor production, NO generation, and upregulation of procoagulant activity by LPS (Escherichia coli O55:B5) at concentrations of 100 pg/ml to 100 ng/ml. The 50% effective dose for LPS was 1 order of magnitude higher than that for activating human macrophages. Macrophages were activated by LPS in the presence of serum or in the presence of albumin demonstrated to be free of LBP. The capacity to react to LPS in the absence of LBP was not due to the acquisition of LBP during a previous culture in serum. It was then established which CD14-specific antibodies block LPS binding to monocytes. Among the CD14-specific antibodies recognizing bovine mononuclear phagocytes (60bca, 3C10, My4, CAM36, VPM65, CMRF31, and TUK4), the first four blocked the binding of LPS-fluorescein isothiocyanate to bovine monocytes at low concentrations. Anti-CD14 antibodies did not block LPS-mediated activation of bovine bone marrow-derived macrophages, monocyte-derived macrophages, and alveolar macrophages. This was observed in experiments in which anti-CD14 concentrations exceeded the 50% inhibitory dose by >30-fold (3C10 and My4) or >300-fold (60bca), as defined in the binding assay described above. Monocyte-derived macrophages from an animal deficient in beta2 integrins and control macrophages were activated by similar concentrations of LPS, suggesting that beta2 integrins are not important bovine LPS receptors. Thus, in bovine macrophages, LPS recognition pathways which are independent of exogenous LBP, of membrane-expressed CD14, and of beta2 integrins may exist.

Acute-Phase Proteins↗
PubMed1997

Competitive binding of viral E2 protein and mammalian core-binding factor to transcriptional control sequences of human papillomavirus type 8 and bovine papillomavirus type 1.

The promoter P7535 of human papillomavirus type 8 and the promoter P7185 of bovine papillomavirus type 1 are negatively regulated by viral E2 proteins via the promoter proximal binding sites P2 and BS1, respectively. Mutations of these E2 binding sites can reduce basal promoter activity. This suggests binding of a transcription-stimulating factor and may indicate that repression by E2 is due to competitive binding of viral and cellular proteins. A computer search revealed putative binding sites for core-binding factor (CBF; also referred to as PEA2, PEBP2, or AML), overlapping with P2 and BS1. Binding of recombinant CBF proteins to these sites was confirmed by band shift analysis. Competition of CBF and E2 protein for DNA binding was shown for both human papillomavirus type 8 and bovine papillomavirus type 1. The importance of CBF-E2 competition in E2-mediated repression could be demonstrated by comparing the E2 effect on P7185 activity in two cell lines containing different amounts of endogenous CBF. In cells with large amounts of CBF, E2 repressed P7185 wild-type constructs to the basal promoter activity of a mutant (50%) that could not bind this protein any more. In contrast, in a cell line containing small amounts of CBF, the promoter activities of constructs with wild-type and mutated CBF binding sites hardly differed and specific repression by E2 was not detectable.

Animals↗
PubMed1997

Macrophages infected with cytopathic bovine viral diarrhea virus release a factor(s) capable of priming uninfected macrophages for activation-induced apoptosis.

Bovine bone marrow-derived macrophages infected with the cytopathic biotype of bovine viral diarrhea virus released an antiviral activity into the supernatant which was tentatively characterized as type I interferon because of its physicochemical properties. Such supernatants primed both infected and uninfected macrophages for decreased nitric oxide production and apoptosis in response to lipopolysaccharide. This finding strongly suggests a role of this pathway in the pathogenesis of mucosal disease, a lethal form of infection with cytopathic bovine viral diarrhea virus in which the principal lesions are located in the oral cavity and the gastrointestinal tract, which are known to contain a high concentration of endotoxin.

Animals↗
PubMed1996

Chronic sun exposure and age are inversely associated with nevi in adult renal transplant recipients.

In 126 adult renal transplant recipients who had survived their transplantation for at least 8 years, we determined whether numbers of nevi and the presence of clinically atypical nevi were related to chronic sun exposure. On the basis of a skin examination, three groups were defined: patients with at least one clinically a typical nevus; patients with only clinically normal nevi: and patients without any nevi. The prevalence odds ratio of having any clinically atypical nevi as compared to having only clinically normal nevi was calculated in a logistic model, in relation to gender, skin type, age, sun exposure, and number of keratotic skin lesions present. Similarly, the prevalence odds ratio of having 30 or more nevi compared to fewer than 30 nevi was calculated. We found an inverse association between chronic sun exposure and age with numbers of nevi in adult renal transplant recipients. The presence of clinically atypical nevi was also inversely associated with chronic sun exposure, but this association disappeared after adjustment for age. We did not observe an association of nevi with the number of keratotic skin lesions, nor with humoral immune responses against human papillomavirus and the presence of certain HLA antigens, which are factors associated with nonmelanoma skin cancer in renal transplant recipients. Chronic sun exposure and age appeared to be strong determinants for decreased numbers of nevi in adult renal transplant recipients. Infection with human papillomaviruses does not appear to play an important role.

Adult↗
PubMed1996

E2 represses the late gene promoter of human papillomavirus type 8 at high concentrations by interfering with cellular factors.

The late gene promoter P7535 of the epidermodysplasia verruciformis-associated human papillomavirus type 8 (HPV8) is regulated by the viral E2 protein. Transfection experiments performed with the human skin keratinocyte cell line RTS3b and P7535 reporter plasmids revealed transactivation at low amounts and a repression of basal promoter activity at high amounts of E2 expression vector. This repression was promoter specific and correlated with the amount of transiently expressed E2 protein. Mutational analyses revealed that the negative regulation of P7535 activity is mediated by the low-affinity E2 binding site P2, which is separated by one nucleotide from the P7535 TATA box. Biochemical and genetic analyses suggested that repression is due to a displacement of the TATA-box binding protein by E2 and an interference of E2 with promoter-activating cellular factors that specifically recognize the P2 sequence. The high conservation of the P2 sequence among several papillomaviruses (epidermodysplasia verruciformis-associated HPVs, HPV1, cottontail rabbit papillomavirus, and bovine papillomavirus type 1) in the vicinity of the late gene promoter cap site suggests that an interplay of E2 and cellular factors at this sequence element is important for the expression of structural proteins.

Animals↗