Immigration and sexual partner risk among Latino adolescents in San Francisco.

Sexual partner characteristics increase risk for adverse reproductive health outcomes. Evidence is limited regarding whether choice of sexual partners among Latino adolescents changes with U.S. acculturation/adaptation. We used generalized estimating equations to assess the associations between immigrant generation (recent immigrant, 1.5 [immigrated prior to adolescence], 2nd and 3rd) and sexual partner risk in a prospective cohort study of 411 Latino adolescents aged 14-19. We examined three measures of partner risk and mediating effects of family influence (familism and parental monitoring). The odds of reporting a partner with frequent substance use increased with increasing immigrant generation (odds ratios (OR) [reference = recent immigrants]: 2.3, 3.4, and 5.6) as did having a partner who was in a gang/incarcerated (OR [reference = recent immigrants]: 2.4, 3.6, and 5.7). Though the odds of having high-risk partners decreased with higher parental monitoring, neither family influence measure mediated these relationships. Findings underscore the need for a prevention focus on partner choice with attention to increased risk with increasing U.S. generation.

Gang exposure and pregnancy incidence among female adolescents in San Francisco: evidence for the need to integrate reproductive health with violence prevention efforts.

Among a cohort of 237 sexually active females aged 14-19 years recruited from community venues in a predominantly Latino neighborhood in San Francisco, California, the authors examined the relation between gang exposure and pregnancy incidence over 2 years of follow-up between 2001 and 2004. Using discrete-time survival analysis, they investigated whether gang membership by individuals and partners was associated with pregnancy incidence and determined whether partnership characteristics, contraceptive behaviors, and pregnancy intentions mediated the relation between gang membership and pregnancy. Pregnancy incidence was determined by urine-based testing and self-report. Latinas represented 77% of participants, with one in five born outside the United States. One quarter (27.4%) became pregnant over follow-up. Participants' gang membership had no significant effect on pregnancy incidence (hazard ratio = 1.25, 95% confidence interval: 0.54, 3.45); however, having partners who were in gangs was associated with pregnancy (hazard ratio = 1.90, 95% confidence interval: 1.09, 3.32). The male partner's perceived pregnancy intentions and having a partner in detention each mediated the effect of partner's gang membership on pregnancy risk. Increased pregnancy incidence among young women with gang-involved partners highlights the importance of integrating reproductive health prevention into programs for gang-involved youth. In addition, high pregnancy rates indicate a heightened risk for sexually transmitted infections.

High throughput detection of retrovirus-associated reverse transcriptase using an improved fluorescent product enhanced reverse transcriptase assay and its comparison to conventional detection methods.

The development and application of a novel, sensitive TaqMan fluorescent probe-based product enhanced RT test (F-PERT) for the detection of retrovirus are described. The assay allows discrimination between the amplification signals generated by genuine positive signals that result from retroviral RT activity and the RT-like activity from DNA polymerases. The RT-like activity from DNA polymerases was suppressed by the addition of activated calf-thymus DNA with no reduction in the RT activity. A linear relationship between threshold cycle (C(T)) and the number of virus particles was demonstrated, allowing quantification of retroviruses in unknown samples. The F-PERT assay was able to detect a wide range of retroviral RT activities, including that from porcine endogenous retrovirus (PoERV), murine leukaemia virus (MLV), simian foamy virus (SFV), simian immunodeficiency virus (SIVmac) and squirrel monkey retrovirus (SMRV). The detection limit of SMRV, MLV and PoERV was approximately 100 virion particles and the test was able to detect at least 10(2) molecules of purified RT enzyme. RT activity was not detected in cellular lysates and supernatants from MRC-5, BT, VERO, or Raji cells, whereas RT activity was detected in C1271, Mus dunni, K-Balb, BHK-21, CHO-K1, SP2/0-Ag14 and NSO cell supernatants. RT activity was also detected in the Spodoptera cell line Sf9.

BPV-4 induces amplification and activation of 'silent' BPV-1 in a sub-line of C127 cells.

BPV-4-induced malignant transformation of C127 mouse fibroblasts in vitro is the result of a 'hit and run' mechanism. Viral DNA is lost on continued subculture of transformed cell lines without loss of any malignant characteristics. The DNA from these cells harbours specific amplified sequences. Two such amplified fragments of approximately 10 kb and 12 kb were molecularly cloned and designated HL-10 and HL-12 respectively. HL-10 transformed C127 cells efficiently and therefore encodes a transforming function, whereas the 12 kb clone did not. Heteroduplexes showed that HL-12 was homologous to HL-10 except for two additional tandem copies of an approximately 1.7 kb sequence. Sequence analysis of HL-10 revealed that the clone contained a 5.2 kb region from BPV-1 including the transforming ORFs. Transformation studies have shown differences between HL-10 and BPV-1, indicating that the host flanking sequences may contribute to the transforming potential of the BPV-1 ORFs. The BPV-1 DNA was associated with sequences homologous to murine autonomously replicating sequences (ARS) implicated in the establishment of multiple tandem DNA repeats. As the parental cells contain the set of sequences amplified in transformed cells in single copy and show none of the characteristics of transformed cells, we conclude that BPV-4 has activated these sequences by amplification and rearrangement. These phenomena may be mediated through an interaction between BPV-4 proteins and the BPV-1 origin of DNA replication or via the ARS region.

First steps in the development of an information and counselling service for women with an abnormal smear result.

A study was conducted to develop and evaluate an information leaflet and to investigate the acceptability of a counselling service for women with an abnormal smear result. A newly constructed information leaflet which addressed concerns related to receipt of an abnormal smear result and its medical management was compared for ease of readability with five other leaflets in current use and found to be superior. 144 women were given the leaflet either prior to a colposcopy examination or outpatient ablative treatment and randomly assigned to two recruitment strategies to examine the acceptability of a counselling interview. There was no significant difference between the two strategies and an uptake rate of 80% suggested that women welcomed such an opportunity. An interview evaluation schedule yielded a 98% positive response rate which indicated that the women were satisfied with the counsellor and found the interview useful. Significant differences emerged before and after medical intervention. Patients reported less anxiety, improved mood, and less distress related to the smear result and subsequent medical procedures immediately after the medical interventions (P less than 0.001).

The Harvey ras 1 gene is activated in papillomavirus-associated carcinomas of the upper alimentary canal in cattle.

The possible activation of ras sequences in papillomavirus-associated carcinomas of the upper alimentary canal of cattle was investigated by restriction enzyme and hybridization analysis, and by DNA-mediated transformation of NIH3T3 cells. In three cancers, a squamous cell carcinoma of the palate, a squamous cell carcinoma of the rumen, and a transitional cell carcinoma of the urinary bladder, repetitive DNA sequences present in the Ha-ras 1 locus showed anomalous restriction patterns, indicating rearrangements and, in the case of the palate cancer, amplification. Genomic DNA from several cancers was capable of inducing focus formation in the NIH3T3 transformation test. DNA from primary, secondary and tertiary transformants was analysed by hybridization to bovine ras probes and by nucleotide sequencing of polymerase chain reaction products. Bovine Ha-ras 1 sequences were found in all transformants, but no nucleotide differences were detected in exon 1 or exon 2 between normal, cancer and transformed cells. It is concluded that the Ha-ras 1 gene is activated in alimentary canal carcinomas, although the activating mutation has not yet been mapped. The possible relationship between papillomavirus infection and activation of the ras gene is considered.

Multiple Harvey-ras genes in the bovine genome.

Three different Harvey-ras (Ha-ras) genes have been identified in the bovine genome by screening a lambda phage-bovine DNA library with the ras gene of the Harvey murine sarcoma virus. The genes have been characterized by hybridization and heteroduplex analysis with both the viral and human Ha-ras genes. Based on heteroduplex mapping, the putative direction of transcription and the approximate position of the coding regions of the bovine genes were established. Two genes, bovine Ha-ras 1 and 2, both show an arrangement of exons and introns typical of c-Ha-ras genes. However, they are distinct entities as they have different nucleotide sequences and physical maps, and heteroduplexes between them contain a region of non-homology upstream of exon 1. The third gene, c-Ha-ras 3, does not contain introns and is a pseudogene, analogous to human c-Ha-ras 2. The nucleotide sequence of both Ha-ras 1 and Ha-ras 2 has been determined and shows that Ha-ras 1 encodes a bona fide ras protein, whereas Ha-ras 2 has diverged considerably from a recognizably functional sequence.

Transplantation and morphological studies of primary and passaged murine radiation-induced myeloid leukaemias.

Myeloid leukaemia can be induced reproducibly in CBA/H male mice following X-irradiation. After serial passage of the leukaemic cells into syngeneic recipients, they grow faster and require fewer cells for a take. Transplantation of primary leukaemias requires high cell doses unlike passaged lines derived from them. Passaging at low cell doses retains their primary-like growth and morphological properties. It would seem that these low cell dose passages may be a more useful model which can be used for investigating the biology and therapeutic responses of myeloid leukaemia than routinely passaged cell lines.