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Biomedical subjects

S L Martin

Publications and source records attributed to S L Martin.

At least 55 records · Page 3Linked to original sources
PubMed1999

Violence victimization experiences of pregnant prisoners.

The violence victimization histories of pregnant incarcerated women were studied in relation to those of pregnant health department patients in North Carolina. Prisoners were twice as likely as health department patients to have experienced both physical and sexual violence compared to no violence, and over three times more likely to have experienced both types of violence compared to only one type. Implications for research and program development are noted.

Adolescent↗
PubMed1999

Women inmates' risky sex and drug behaviors: are they related?

The large concentration of female illicit drug users in state correctional facilities prompted an examination of the associations among different types of drug use and sexual risk factors related to human immunodeficiency virus (HIV) among women inmates. A consecutive sample of 805 women felons admitted to the North Carolina Correctional Institution for Women between July 1991 and November 1992 was interviewed. Of these inmates, 651 had complete information on relevant characteristics. Of the women inmates, 73% had used drugs prior to incarceration; most women were crack smokers only (33%), followed by non-drug users (27%), other drug users (19%), crack-smoking injecting drug users (15%), and injecting drug users only (6%). Inconsistent condom use with multiple sex partners, a history of a diagnosed sexually transmitted disease (STD), a drug-injecting sex partner, or exchanging sex for money or drugs prior to incarceration were reported by 55% of the women. Sexual risk factors differed across different types of drug users, with crack-smoking injectors being placed at greatest potential risk for exposure to heterosexually transmitted HIV, followed by injecting drug users, crack smokers, and then other drug users. Given the differential associations between sexual risk factors and types of drug use, prison-based sexual-risk reduction strategies should be tailored to specific types of drug users. In times of limited resources, special attention should be given to crack smokers and/or drug injectors.

Adult↗
PubMed1999

Violence in the lives of pregnant teenage women: associations with multiple substance use.

Using data from a consecutive sample of approximately 700 prenatal patients aged 12 to 19, the extent of violence and substance use in the lives of these women was examined, as were associations between violence and substance use. The findings show that 29% of the study participants had been victims of violence, with 15% experiencing physical violence only, 5% sexual violence only, and 9% both physical and sexual violence. Adjusted odds ratios (ORs) and 95% confidence intervals (CIs) from logistic regression analyses showed that, after controlling for confounding factors, victims were more likely than nonvictims to use cigarettes, alcohol, and illicit drugs, with victims of both physical and sexual violence being the most likely to use each type of substance. Ordinal logistic regression analysis found that, compared to nonvictims, violence victims were more likely to have more severe patterns of substance use (use multiple types of substances), with victims of both physical and sexual violence being the most likely to be multiple substance users. These findings underline the importance of both violence and substance use as health concerns among our youth.

Adolescent↗
PubMed1999

Phase variation in Helicobacter pylori lipopolysaccharide due to changes in the lengths of poly(C) tracts in alpha3-fucosyltransferase genes.

The lipopolysaccharide (LPS) of Helicobacter pylori expresses the Lewis x (Lex) and/or Ley antigen. We have shown previously that H. pylori LPS displays phase variation whereby an Lex-positive strain yields variants with different LPS serotypes, for example, Lex plus Ley or nonfucosylated polylactosamine. H. pylori has two alpha3-fucosyltransferase genes that both contain poly(C) tracts. We now demonstrate that these tracts can shorten or lengthen randomly, which results in reversible frameshifting and inactivation of the gene products. We provide genetic and serological evidence that this mechanism causes H. pylori LPS phase variation and demonstrate that the on or off status of alpha3-fucosyltransferase genes determines the LPS serotypes of phase variants and clinical isolates. The role of the alpha3-fucosyltransferase gene products in determining the LPS serotype was confirmed by structural-chemical analysis of alpha3-fucosyltransferase knockout mutants. The data also show that the two alpha3-fucosyltransferase genes code for enzymes with different fine specificities, and we propose the names futA and futB to designate the orthologs of the H. pylori 26695 alpha3-fucosyltransferase genes HP0379 and HP0651, respectively. The data also show that the alpha3-fucosylation precedes alpha2-fucosylation [corrected], an order of events opposite to that which prevails in mammals. Finally, the data provide an understanding at the molecular level of the mechanisms underlying LPS diversity in H. pylori, which may play an important role in adaptation to the host.

Fucosyltransferases↗
PubMed1999

Capillary filtration coefficient, vascular resistance, and compliance in isolated mouse lungs.

Although many recently produced transgenic mice possess gene alterations affecting pulmonary vascular function, there are few baseline measurements of vascular resistance and permeability. Therefore, we excised the lungs of C57/BL6 mice and perfused them with 5% bovine serum albumin in RPMI-1640 culture medium at a nominal flow of 0.5 ml/min and ventilated them with 20% O(2)-5% CO(2)-75% N(2). The capillary filtration coefficient, a sensitive measurement of hydraulic conductivity, was unchanged over 2 h (0.33 +/- 0.03 ml. min(-1). cmH(2)O(-1). 100 g(-1)) in a control group ventilated with low peak inflation pressures (PIP) but increased 4. 3-fold after high PIP injury. Baseline pulmonary vascular resistance was 6.1 +/- 0.4 cmH(2)O. ml(-1). min. 100 g(-1) and was distributed 34% in large arteries, 18% in small arteries, 14% in small veins, and 34% in large veins on the basis of vascular occlusion pressures. Baseline vascular compliance was 5.4 +/- 0.3 ml. cmH(2)O(-1). 100 g(-1) and decreased significantly with increased vascular pressures. Baseline pulmonary vascular resistance was inversely related to both perfusate flow and microvascular pressure and increased to 202% of baseline after infusion of 10(-4) M phenylephrine due to constriction of large arterial and venous segments. Thus isolated mouse lung vascular permeability, vascular resistance, and the longitudinal distribution of vascular resistance are similar to those in other species and respond in a predictable manner to microvascular injury and a vasoconstrictor agent.

Animals↗
PubMed1999

Voluntary HIV testing in prison: do women inmates at high risk for HIV accept HIV testing?

This study examined the proportion of women inmates who accepted HIV testing and the sociodemographic, criminal, and HIV-related risk characteristics associated with accepting such testing in a state prison offering voluntary HIV testing. A consecutive sample of 805 women felons admitted to the North Carolina Correctional Institution for Women between July 1991 and November 1992 was interviewed. Of these inmates, 680 (84%) granted permission to access their medical records and had complete information on relevant characteristics. Seventy-one percent of the women inmates accepted HIV testing. In multivariate analysis, the exchange of sex for money or drugs and the conviction for a drug crime were significantly associated with accepting HIV testing. Injection drug use, drug-injecting sex partners, and a history of a sexually transmitted disease were not significantly associated with accepting HIV testing. A prison-based voluntary HIV testing program appears to be reaching a substantial proportion of women inmates potentially at risk for HIV, especially women inmates who exchanged sex for money or drugs.

AIDS Serodiagnosis↗
PubMed1998

Prenatal detection of congenital idiopathic cataracts.

Congenital cataracts can cause irreversible loss of sight unless surgery is performed soon after birth. In the case reported here an obstetric ultrasound detected congenital cataracts in an otherwise normal fetus without any history of familial syndrome, infection or metabolic disorder. The lens opacity was detectable on transabdominal ultrasound at 18 weeks' gestation and the appearance was unchanged near-term. An otherwise normal boy was delivered at term and underwent surgery in the first week of life. Prenatal detection of the cataracts by means of high quality obstetric ultrasound facilitated early surgery and preservation of sight.

Adult↗
PubMed1998

Recombination between subtypes creates a mosaic lineage of LINE-1 that is expressed and actively retrotransposing in the mouse genome.

LINE-1, or L1, elements are retrotransposons that have amplified to high-copy number during the evolution of mammals. L1 appears to amplify in waves, spawning large numbers of progeny such that elements with distinct sequence features dominate the dispersal process in a given window of time. This process generates discrete subfamilies of L1 within mammalian genomes, with the oldest being remnants, or fossils, of earlier waves of amplification. In mice, at least three distinct subfamilies of L1 were distinguished by their unique 5' ends, A, F and V. These subfamilies amplified at distinct times in the evolution of mice, with A being the youngest and V the oldest; both V and F subfamilies were believed extinct. Recent data established that a variant of the F family, TF, is actively retrotransposing. We demonstrate here that members of the TF subfamily are abundantly expressed in mouse cells and encode the major protein constituent of L1 ribonucleoprotein particles. Although members of the TF subfamily are not as numerous in the genomes of laboratory mice as are members of the older A and F subfamilies, they appear to have been activated some time ago during mouse evolution, in the common ancestor of Mus spretus and Mus domesticus. Phylogenetic analysis demonstrates that this modern, active form of TF-type L1 has a composite evolutionary history, showing evidence of multiple recombinations between distinct L1 variants, including members of the A and F subfamilies.

Animals↗
PubMed1998

Functional reverse transcriptases encoded by A-type mouse LINE-1: defining the minimal domain by deletion analysis.

Long interspersed elements, or LINEs, are retrotransposons that move via an RNA intermediate. In mice, one polymorphic variant of L1 has amplified relatively recently, giving rise to the A-type subfamily in species belonging to the genus and subgenus Mus. Retrotransposition of LINE-1 (L1) requires the function of the L1-encoded reverse transcriptase that is produced from open reading frame 2 (ORF2). Here, we employ a convenient yeast genetic assay to determine the reverse transcriptase activity of the ORF2 obtained from three A-type L1 elements: one, a cDNA from the RNA in ribonucleoprotein particles; another with a purported inactivating mutation; and the third, a hypothetical ancestral construct. Because there are no examples of A-type elements that have transposed recently to inactivate a gene, this assay is the first step towards demonstrating the functional capability of mouse A-type LINE-1 elements. One of the three elements was believed to have been inactivated during evolution by the substitution of leucine for a highly conserved phenylalanine or tryptophan residue among known reverse transcriptases. This mutation did not inactivate the L1 reverse transcriptase in the yeast assay; thus, all three of the elements tested encoded reverse transcriptase activity. We further examined the minimal reverse transcriptase domain within ORF2 by creating a series of deletions. The results demonstrate that removal of the L1 endonuclease domain from the N-terminal region of ORF2 does not affect reverse transcriptase activity as determined by this assay, and that approximately half of the ORF2 coding sequence from mouse A-type L1 elements is required for functional reverse transcriptase.

Animals↗
PubMed1998

An actively retrotransposing, novel subfamily of mouse L1 elements.

Retrotransposition of LINEs and other retroelements increases repetition in mammalian genomes and can cause deleterious mutations. Recent insertions of two full-length L1s, L1spa and L1Orl, caused the disease phenotypes of the spastic and Orleans reeler mice respectively. Here we show that these two recently retrotransposed L1s are nearly identical in sequence, have two open reading frames and belong to a novel subfamily related to the ancient F subfamily. We have named this new subfamily TF (for transposable) and show that many full-length members of this family are present in the mouse genome. The TF 5' untranslated region has promoter activity, and TF-type RNA is abundant in cytoplasmic ribonucleoprotein particles, which are likely intermediates in retrotransposition. Both L1spa and L1Orl have reverse transcriptase activity in a yeast-based assay and retrotranspose at high frequency in cultured cells. Together, our data indicate that the TF subfamily of L1s contains a major class of mobile elements that is expanding in the mouse genome.

Animals↗
PubMed1998

Women in a prenatal care/substance abuse treatment program: links between domestic violence and mental health.

OBJECTIVES: This study examines the prevalence of violence experienced by patients enrolled in the Step by Step program, a combined prenatal care/substance abuse treatment program at the Wake County Health Department in North Carolina. In addition, potential associations between violence and sociodemographic characteristics, substance use, and mental health are investigated. METHOD: All prenatal care/substance abuse treatment patients who met study eligibility criteria (N = 84) were assessed by health care providers. Descriptive statistics and bivariate analyses were used to compare victims of violence and nonvictims on a wide range of variables. Multiple linear regression analysis estimated the impact of the women's experiences of violence on their levels of mental health symptoms while controlling for confounding factors. RESULTS: Forty-two percent of patients had been victims of both sexual and physical violence, and 30% had been victims of physical violence alone. The combination of sexual and physical violence was significantly less common among African-American women compared with other women. No other significant differences were found between victims and nonvictims in terms of sociodemographics or substance use. Compared with nonvictims, victims of the combination of sexual and physical violence had significantly elevated levels of general psychological distress as well as elevated levels of hostility, depression, anxiety, interpersonal sensitivity, and somatization. However, no significant differences in levels of mental health symptoms were observed among women who had experienced physical violence in the absence of sexual violence. CONCLUSIONS: Questions concerning experiences of violence, including sexual victimization, should be incorporated into the clinical history-taking procedures of professionals working within prenatal care/substance abuse treatment programs so that effective interventions that take experiences of violence into account can be put into place for these high-risk women.

Adult↗
PubMed1998

[Premature delivery. Epidemiology and prognosis at the Dakar University Hospital Center].

A prospective study included 131 premature births registered from January to December 1996 giving a rate of 28 per 1,000 deliveries. The epidemiological profile was one of a primiparous woman, mean age 25 years, admitted in a clinical situation of irreversible premature birth (91.6%). The prematurely born infant was hypotrophic in 48.8% of the cases with term less than or equal to 32 weeks. Vaginal delivery was achieved in most cases. Risk factors identified were: poor prenatal care (no prenatal check-up in 25%) and obstetrical factors (29.8%). The neonatal outcome included neonatal suffering (64.7%) and high mortality (30.7%). Care of premature infants is relatively costly with a mean daily cost of $US 30 per day besides the cost of laboratory tests and personnel costs.

Adult↗
PubMed1997

In vitro properties of the first ORF protein from mouse LINE-1 support its role in ribonucleoprotein particle formation during retrotransposition.

LINEs are transposable elements, widely distributed among eukaryotes, that move via reverse transcription of an RNA intermediate. Mammalian LINEs have two ORFs (ORF1 and ORF2). The proteins encoded by these ORFs play important roles in the retrotransposition process. Although the predicted amino acid sequence of ORF1 is not closely related to any known proteins, it is highly basic; thus, it has long been hypothesized that ORF1 protein functions to bind LINE-1 (L1) RNA during retrotransposition. Cofractionation of ORF1 protein and L1 RNA in extracts from both mouse and human embryonal carcinoma cells indicated that ORF1 protein binds L1 RNA, forming a ribonucleoprotein particle. Based on UV crosslinking and electrophoretic mobility-shift assays using purified components, we demonstrate here that the ORF1 protein encoded by mouse L1 binds nucleic acids with a strong preference for RNA and other single-stranded nucleic acids. Furthermore, multiple copies of ORF1 protein appear to bind single-stranded nucleic acid in a manner suggesting positive cooperativity; such binding characteristics are likely to be facilitated by the protein-protein interactions detected among molecules of ORF1 polypeptide by coimmunoprecipitation. These observations are consistent with the formation of ribonucleoprotein particles containing L1 RNA and ORF1 protein and provide additional evidence for the role of ORF1 protein during retrotransposition of L1.

Animals↗
PubMed1997

Lewis X biosynthesis in Helicobacter pylori. Molecular cloning of an alpha(1,3)-fucosyltransferase gene.

The lipopolysaccharide of certain strains of Helicobacter pylori was recently shown to contain the Lewis X (Lex) trisaccharide (Galbeta-1, 4-(Fucalpha(1,3))-GlcNAc). Lex is an oncofetal antigen which appears on human gastric epithelium, and its mimicry by carbohydrate structures on the surface of H. pylori may play an important part in the interaction of this pathogen with its host. Potential roles for bacterial Lex in mucosal adhesion, immune evasion, and autoantibody induction have been proposed (Moran, A. P., Prendergast, M. M., and Appelmelk, B. J. (1996) FEMS Immunol. Med. Microbiol. 16, 105-115). In mammals, the final step of Lex biosynthesis is the alpha(1,3)-fucosylation of GlcNAc in a terminal Galbeta(1-->4)GlcNAc unit, and a corresponding GDP-fucose:N-acetylglucosaminyl alpha(1,3) fucosyltransferase (alpha(1,3)-Fuc-T) activity was recently discovered in H. pylori extracts. We used part of a human alpha(1, 3)-Fuc-T amino acid sequence to search an H. pylori genomic data base for related sequences. Using a probe based upon weakly matching data base sequences, we retrieved clones from a plasmid library of H. pylori DNA. DNA sequence analysis of the library clones revealed a gene which we have named fucT, encoding a protein with localized homology to the human alpha(1,3)-Fuc-Ts. We have demonstrated that fucT encodes an active Fuc-T enzyme by expressing the gene in Escherichia coli. The recombinant enzyme shows a strong preference for type 2 (e.g. LacNAc) over type 1 (e.g. lacto-N-biose) acceptors in vitro. Certain residues in a short segment of the H. pylori protein are completely conserved throughout the alpha(1,3)-Fuc-T family, defining an alpha(1,3)-Fuc-T motif which may be of use in identifying new fucosyltransferase genes.

Amino Acid Sequence↗
PubMed1997

Recurrent left ventricular false aneurysm.

A recurrent left ventricular false aneurysm 5 years after patch repair and causing progressive congestive heart failure was readily diagnosed by echocardiography and heart catheterization. Its substrate was suture dehiscence of undetermined origin. Urgent repair was successful. The long-term prognosis is guarded.

Aged↗
PubMed1997

Biosynthetic origin of mycobacterial cell wall galactofuranosyl residues.

SETTING: Mycobacterial galactofuran is essential to the linking of the peptidoglycan and mycolic acid cell wall layers. Galactofuran biosynthesis should thus be essential for viability. OBJECTIVE: The objective was to determine the pathway of galactofuranosyl biosynthesis and to clone a gene encoding an essential enzyme necessary for its formation. DESIGN: Specific enzymatic conversions involved in formation of galactopyranose and galactofuranose residues in other bacteria were tested for in Mycobacterium smegmatis. M. tuberculosis deoxyribonucleic acid (DNA) was identified by homology. RESULTS: It was shown that the de novo synthesis of the galactose carbon skeleton occurred in M. smegmatis by the transformation of UDP-glucopyranose to UDP-galactopyranose via the enzyme UDP-glucose 4-epimerase (E.C. 5.1.3.2). The N-terminal sequence of this enzyme was obtained after purification. The galactose salvage pathway enzyme, UDP-glucose-galactose-1-phosphate uridylyltransferase (E.C. 2.7.7.12), was also shown to be present. The critical biosynthetic transformation of the galactopyranose to galactofuranose ring form was shown to occur at the sugar nucleotide level via the enzyme UDP-galactopyranose mutase (E.C. 5.4.99.9). The M. tuberculosis DNA encoding this enzyme was sequenced, the gene expressed in Escherichia coli, and the expected enzymatic activity demonstrated. CONCLUSION: Galactofuranose biosynthesis can now be pursued as a potential drug target in M. tuberculosis.

Amino Acid Sequence↗