Early acquisition of homozygous deletions of p16/p19 during squamous cell carcinogenesis and genetic mosaicism in bladder cancer

We looked for p16/p19 deletion and p16 promoter methylation, as well as loss of 9p21 heterozygosity in pure squamous cell carcinomas (SCC), and in transitional cell carcinomas (TCC) of the bladder with SCC components. Homozygous deletion of p16/p19 was detected in 11 of 21 (52%) cases of pure SCCs and in three of ten (30%) cases of TCC with SCC. Three cases of TCC with SCC had p16/p19 deletion, hypermethylation of the p16 promoter, or LOH on 9p21 only in the SCC components, suggesting that these molecular alterations occurred preferentially in SCC. Interestingly, homozygous deletion of p16/p19 was observed in squamous metaplasia from bladder cancer patients (five of 11, 45%), showing that this change occurred in preneoplastic cells. On the other hand, p16/p19 deletions were not found in squamous metaplasias from non cancerous patients. Hypermethylation of the p16 promoter was observed in two of 14 tumors (14%) and none of seven metaplasias examined. These data suggest that: (a) p16/p19 deletion is associated with early carcinogenesis of SCC of the bladder, and squamous metaplasia of the bladder cancer patient has already sustained genetic changes found in cancer, and (b) genetic mosaicism occurs in cases of TCC with SCC, with the SCC component showing more frequent 9p21 alterations than the TCC component.     

Pituitary adenylate cyclase activating polypeptide induces multiple signaling pathways in rat peritoneal mast cells

Pituitary adenylate cyclase activating polypeptide (PACAP) is a high-affinity ligand for at least two types of G-protein coupled receptors, the PACAP type 1 and type 2 receptor. In this study it is demonstrated that the C-terminal PACAP-fragment PACAP(6-27) stimulates serotonin release from rat peritoneal mast cells with higher potency (EC50: 0.2 vs. 2.0 microM) than the PACAP receptor ligand PACAP(1-27). PACAP-induced degranulation of rat peritoneal mast cells was abolished by pertussis toxin and by benzalkonium chloride (IC50: 9.1 microg/ml) indicating the involvement of heterotrimeric G-proteins of the Gi-type. The PACAP effect was also reduced by inhibitors of the phosphatidylinositol specific phospholipase C ((U73122), IC50: 4 microM; (ET-18-O-CH3), IC50: 18 microM), by D609, a specific inhibitor of the phosphatidylcholine specific phospholipase C (IC50: 41 microM), by the protein kinase C-inhibitor staurosporine (IC50: 0.6 microM) and by the lipoxygenase inhibitor nordihydroguaiaretic acid (NGDA) but not by indomethacin. It is concluded that PACAP peptides stimulate secretion in rat peritoneal mast cells in a PACAP receptor-independent manner, probably via direct activation of heterotrimeric G-proteins of the Gi-type; these G-proteins may lead to a sequential activation of different signaling cascades (see above), which may converge at the level of one or more staurosporine-sensitive protein kinase.     

Pro-apoptotic effect of the hepatitis B virus X gene

The hepatitis B virus (HBV) is a common human pathogen that causes acute and chronic liver disease. Persistent HBV infection is strongly associated with the development of hepatocellular carcinoma. The contribution of the viral regulatory protein HBx in liver oncogenesis has been supported by our recent studies in a transgenic mouse model, showing that HBx cooperates with c-myc by accelerating the onset of primary liver tumors. Here we show that liver expression of HBx is associated with increased rates of spontaneous apoptosis in liver cells from two different transgenic lines. In transient transfection assays, overexpression of HBx in the established hepatocyte cell line MMHD3 and in human hepatoma cells HepG2 was found to induce apoptosis in a dose-dependent manner. These data suggest that HBx might trigger an apoptotic process in HBV-infected hepatocytes, in turn possibly favoring liver regeneration and accumulation of genetic alterations, ultimately leading to liver cell transformation in chronically infected patients.     

Prevalence of Porphyromonas gingivalis and periodontal health status

Periodontitis is a common, progressive disease that eventually affects the majority of the population. The local destruction of periodontitis is believed to result from a bacterial infection of the gingival sulcus, and several clinical studies have provided evidence to implicate Porphyromonas gingivalis. If P. gingivalis is a periodontal pathogen, it would be expected to be present in most subjects with disease and rarely detected in subjects with good periodontal health. However, in most previous studies, P. gingivalis has not been detected in the majority of subjects with disease, and age-matched, periodontally healthy controls were not included for comparison. The purpose of the study reported here was to compare the prevalence of P. gingivalis in a group with periodontitis to that of a group that is periodontally healthy. A comprehensive sampling strategy and a sensitive PCR assay were used to maximize the likelihood of detection. The target sequence for P. gingivalis-specific amplification was the transcribed spacer region within the ribosomal operon. P. gingivalis was detected in only 25% (46 of 181) of the healthy subjects but was detected in 79% (103 of 130) of the periodontitis group (P < 0.0001). The odds ratio for being infected with P. gingivalis was 11.2 times greater in the periodontitis group than in the healthy group (95% confidence interval, 6.5 to 19.2). These data implicate P. gingivalis in the pathogenesis of periodontitis and suggest that P. gingivalis may not be a normal inhabitant of a periodontally healthy dentition.     

The role of the B cell receptor V region in peripheral B cell survival

We investigate the role of the antigen-specific B cell receptor (BCR) in the establishment and maintenance of the peripheral B cell pools. We studied the fate of a population of transgenic B cells expressing a BCR without V region (Tg(deltaVmu)). We found that the Tg(deltaVmu) B cells can populate the peripheral B cell pools in the absence of other B cells, but when in the presence of a second population of non-transgenic B cells, they are virtually absent from the mature B cell compartments. By studying the rate of accumulation of 5-bromo-2'-deoxyuridine we show that the peripheral Tg(deltaVmu) B cells have a shorter life-span compared to non-transgenic B cells. By directly comparing the fate of two populations of transgenic B cells, either lacking or expressing a V region, we were able to assign the poorest competitive ability and the short peripheral survival of the Tg(delatVmu) B cells to the lack of an antigen-binding site. The results obtained support the involvement of the V region in the persistence of peripheral B cell populations.     

Use of excretory/secretory antigens in a competition test to follow the kinetics of infection by Fasciola hepatica in cattle

Eight 16-18-month-old Charolais heifers were experimentally infected with Fasciola hepatica. An antigen competition assay was used to follow the kinetics of the infection and was compared to antibody tires and serum liver enzymes. The antigen competition assay was able to detect the presence of infection as soon as 6 days after the start of the experimental infection which is considerably sooner than other methods. Consequently, this assay would be useful in diagnosing fasciolosis early in the prepatent period. The animals were slaughtered at the end of the experiment, the livers recovered and post-mortem fluke burdens determined. However, only serum liver enzyme levels gave any indication of the intensity of infection in the different animals.     

Updating a situation model: a memory-based text processing view

Previous research (J. E. Albrecht & E. J. O'Brien, 1993) demonstrated that readers were aware of an inconsistency between an earlier described characteristic of a protagonist and a subsequent target action carried out by the protagonist. In a series of 5 experiments, a qualification was added to the described characteristic that restricted the conditions under which the characteristic was operative. According to the here-and-now view of mapping, readers should use this qualification to maintain a fully updated model of the protagonist in active memory and should not experience comprehension difficulty when reading the target action. In contrast, according to the memory-based text processing view, the qualification would not be part of the active discourse model. Instead, it would be reactivated when the target action was read. Thus, readers should still experience comprehension difficulty. Results of all 5 experiments were consistent with the memory-based text processing view.     

A sustainable behavioral intervention to increase condom use and reduce gonorrhea among sex workers in Singapore: 2-year follow-up

BACKGROUND: Prostitution is the most important source of transmission of AIDS and sexually transmitted diseases in Asia. We developed and evaluated the sustainability of an intervention to increase condom use and reduce gonorrhea among brothel-based sex workers in Singapore. The intervention focused on developing sex workers' negotiation skills, educating clients, and mobilizing support from peers and health staff in promoting condom use. METHODS: A pretest-posttest design with one intervention site (n = 124) and another comparable control site (n = 122) was maintained for 5 months followed by a time series design to follow up the intervention group for 2 years. RESULTS: At 5 months, the intervention group improved significantly in negotiation skills and were almost twice as likely as controls to always refuse unprotected sex (adjusted rate ratio 1.90, 95% CI 1.22-2.94). Gonorrhea incidence declined considerably by 77.1% in the intervention group compared with 37.6% in the controls. Consistent refusals of unprotected sex in the intervention group increased from 44.4% at baseline to 65.2% at 5 months, 73.6% at 1 year, and 90.5% at 2 years with a corresponding decline in gonorrhea. CONCLUSION: Sustained condom use with a corresponding decline in gonorrhea was achieved by a behavioral and environmental intervention for sex workers.     

Confidence intervals for the receiver operating characteristic area in studies with small samples

RATIONALE AND OBJECTIVES: The authors performed this study to address two practical questions. First, how large does the sample size need to be for confidence intervals (CIs) based on the usual asymptotic methods to be appropriate? Second, when the sample size is smaller than this threshold, what alternative method of CI construction should be used? MATERIALS AND METHODS: The authors performed a Monte Carlo simulation study where 95% CIs were constructed for the receiver operating characteristic (ROC) area and for the difference between two ROC areas for rating and continuous test results--for ROC areas of moderate and high accuracy--by using both parametric and nonparametric estimation methods. Alternative methods evaluated included several bootstrap CIs and CIs with the Student t distribution. RESULTS: For the difference between two ROC areas, CIs based on the asymptotic theory provided adequate coverage even when the sample size was very small (20 patients). In contrast, for a single ROC area, the asymptotic methods do not provide adequate CI coverage for small samples; for ROC areas of high accuracy, the sample size must be large (more than 200 patients) for the asymptotic methods to be applicable. The recommended alternative (bootstrap percentile, bootstrap t, or bootstrap bias-corrected accelerated method) depends on the estimation approach, format of the test results, and ROC area. CONCLUSION: Currently, there is not a single best alternative for constructing CIs for a single ROC area for small samples.