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Biomedical subjects

J C Thomas

Publications and source records attributed to J C Thomas.

At least 55 records · Page 3Linked to original sources
PubMed1997

Self-treatment patterns among clients attending sexually transmitted disease clinics and the effects of self-treatment on STD symptom duration. The Study Group.

OBJECTIVE: To assess patterns of self-treatment and its effects on the duration of sexually transmitted disease (STD) symptoms before medical care. METHODS: A cross-sectional interview survey in public STD clinics (7 U.S. cities). Patients, seeking treatment for STD symptoms or having a known infected sexual contact, reported self-treatment behaviors and symptom duration. Additional data were abstracted from medical charts. RESULTS: Self-treatment, primarily over-the-counter topical medications (54.8%), was reported by 21.8% of 2,508 symptomatic patients. Self-treaters were significantly more likely to be African-American (odds ratio [OR] = 1.8), female (OR = 1.7), over age 30 (OR = 1.3), report > 1 symptom (OR = 1.4), and report a genital lesion (OR = 2.1). Symptom duration was 2 days longer among self-treaters (p < 0.01). African-Americans (OR = 1.5), men (OR = 1.2), and self-treaters of symptoms other than genital lesions (OR = 1.4) had a significantly longer time from symptom onset to receiving medical care. CONCLUSIONS: Self-treatment is common among patients with STDs. Self-treatment of a genital lesion, unlike certain demographic factors and self-treatment of other STD symptoms, did not prolong the time to medical treatment.

Adolescent↗
PubMed1997

Condom and nonoxynol-9 use and the incidence of HIV infection in serodiscordant couples in Zambia.

We aimed to measure the effectiveness of latex condoms and of nonoxynol-9 [N-9] spermicides, in preventing HIV transmission in heterosexual serodiscordant couples in Lusaka. Each couple was examined at clinic visits scheduled at 3-month intervals for one year or more per couple, or until seroconversion or discontinuation. Couples were given condoms and their choice of 3 N-9 products and advised to use both at every intercourse. Sexual exposure was ascertained from coital logs that recorded coitus and barrier method use. HIV serological testing was done at each clinic visit (ELISA and Western blot if positive). One hundred and ten discordant couples were followed for a mean of 17.6 months. Seventy-eight per cent of coital episodes were protected by condoms, 85% by spermicides and 6.4% were unprotected. Fourteen seroconversions occurred (8.7 infections per 100 couple-years [c-y]). The rate was higher among seronegative men than seronegative women. Among couples who reported using condoms at every intercourse the infection rate was 2.3/100 c-y, compared with 10.7/100 c-y among couples using condoms less consistently (rate ratio [RR] 0.2; 95% confidence interval [CI] 0-1.6). Among couples who reported using N-9 at every intercourse, the seroconversion rate was 6.9/100 c-y; among couples who reported less than full-time N-9 use, the rate was 8.9/100 c-y (RR 0.8; 95% CI 0.2-2.8). Among the subset of female seronegatives, the N-9 RR was 0.5 (95% CI 0.1-3.8). But when we calculated HIV rates according to N-9 consistency in coital acts when condoms were not used, there was no evidence of protection with higher N-9 use. Consistent use of latex condoms reduces the incidence of HIV infection, but the association between N-9 spermicides and HIV is less clear. The current study could not provide compelling data on the impact of N-9 spermicide use on risk of HIV infection. The study's small size, as well as the consistency of concurrent condom use, limited our inferences. Available spermicide products must be studied further.

Adolescent↗
PubMed1997

Sociodemographic factors and the variation in syphilis rates among US counties, 1984 through 1993: an ecological analysis.

OBJECTIVES: Syphilis in the United States is focally distributed, with high incidence rates in the South and in metropolitan areas nationwide. In this study an ecological analysis, using the county as the unit of analysis, was performed to generate hypotheses about community-level determinants of syphilis rates. METHODS: Bivariate rank correlations and multivariate, backward stepwise elimination linear regressions were performed. Mean annual incidence of primary- and secondary-stage syphilis in a county was the dependent variable, and county sociodemographic characteristics (from census data) were the independent variables. RESULTS: In the multivariate regression model, sociodemographic characteristics accounted for 71% of the variation in syphilis rates among counties. With other factors accounted for, the most highly correlated characteristics were percentage non-Hispanic Black population, county location in the South, percentage of the population that was urban, percentage Hispanic population, and percentage of births to women younger than 20 years. CONCLUSIONS: Most of the variation in syphilis rates among counties is accounted for by sociodemographic characteristics. Identification and remediation of modifiable health determinants for which these factors are markers are needed to improve the health status of these populations.

Adolescent↗
PubMed1996

Rural gonorrhea in the southeastern United States: a neglected epidemic?

Some rural counties in the southeastern United States are experiencing high rates of gonorrhea; however, existing knowledge of epidemiologic patterns of gonorrhea within communities is from urban areas. This paper describes the epidemiology of gonorrhea within a rural county of North Carolina and compares it with the patterns described for large cities. Data include gonorrhea reports from private physicians and the county health department from August 11, 1992, to August 10, 1993, and ethnographic interviews. The rate among males (1,602 cases per 100,000 person-years) was twice that among females. The risk of reinfection within 6 months of an initial infection (12.9%) was high compared with risks in urban settings. Although case numbers did not cluster by geographical area as described for some cities, case rates did. Factors favoring transmission in rural communities include greater poverty and fewer health care resources than in urban settings, the exchange of sex for crack cocaine, and a lack of anonymity that may cause some people to avoid seeking treatment or acknowledging risky sexual behaviors in a clinical setting. Addressing high rural rates will entail improving access to care, taking extra measures to ensure confidentiality, and dispelling the myth that high rates are limited to cities.

Adolescent↗
PubMed1996

The development and use of the concept of a sexually transmitted disease core.

A small proportion of people experiencing a sexually transmitted disease (STD), who are frequently infected or often transmit the infection, has been referred to as the "core." Though a prominent paradigm in the epidemiology of STDs, there is confusion about the meaning of the core. The term has been used to refer variously to people who are infected a large proportion of the time, infect more than one other person, are repeatedly infected, or are prostitutes or their clients and to geographic areas with large numbers of cases. Three perspectives that have contributed to the development of the concept of an STD core were identified: mathematical, clinical-epidemiologic, and sociocultural. These different perspectives share the common aim of identifying strategic points of intervention to reduce STDs. The value of the concept of an STD core will ultimately derive from its utility in lowering STD rates.

Gonorrhea↗
PubMed1996

Differential transcription of phycobiliprotein components in Rhodella violacea. Light and nitrogen effects on the 33-kilodalton phycoerythrin rod linker polypeptide, phycocyanin, and phycoerythrin transcripts.

In Rhodella violacea phycoerythrin (PE) has two transcripts, a premessenger and a mature messenger (the gene contains an intron). Phycocyanin, which is plastid-encoded, and the 33-kD PE rod linker polypeptide, which is nuclear-encoded, have only one transcript. The PE premessenger had a rapid turnover; mature transcripts were stable in the light and more stable in the dark. In the presence of rifampicin, cells that shifted from dark to light exhibited an active translation of preexisting transcripts. There are indications of a modulation of the nuclear genome expression by the chloroplast; it may involve an unstable, plastid-encoded translational activator. All transcripts disappeared rapidly during nitrogen starvation. If nitrogen addition was carried out in the dark, active transcription and translation resumed as in light conditions, but ceased after 2 d. Both nitrogen and light were required for a total recovery after nitrogen starvation. Compared with the transcripts of phycobilisome components studied so far in cyanobacteria and Rhodophyceae, the mature transcripts of R. violacea are very stable when nitrogen is not limiting. The unstable PE premessenger is a good indicator of active transcription. This organism is therefore an interesting model to study the regulation of gene expression and the interactions between chloroplastic and nuclear genomes.

Amino Acid Sequence↗
PubMed1996

Isolation and characterization of a novel gamma-hexachlorocyclohexane-degrading bacterium.

The natural biotic capacity of soils to degrade gamma-hexachlorocyclohexane (gamma-HCH, lindane) was estimated using an enrichment technique based on the ability of soil bacteria to develop on synthetic media and degrade the xenobiotic compound, used as the sole source of carbon and energy. Bacterial inocula from relatively highly contaminated soils (from wood treatment factories) were found to promote efficiently the degradation of gamma-HCH, which subsequently permitted isolation of a competent gamma-HCH-degrading microorganism. The decrease of gamma-HCH concurrently with the release of chloride ions and the production of CO2 demonstrated the complete mineralization of gamma-HCH mediated by the isolate. This was confirmed by gas chromatography-mass spectrometry analyses showing that degradation subproducts of gamma-HCH included an unidentified tetrachlorinated compound and subsequently 1,2,4-trichlorobenzene and 2,5-dichlorophenol. The two linA- and linB-like genes coding, respectively, for a gamma-HCH dehydrochlorinase and a dehalogenase were characterized by using a PCR strategy based on sequence homologies with previously published sequences from Sphingomonas paucimobilis UT26. Nucleotide sequence analysis of the linA-like region revealed the presence of a 472-bp open reading frame exhibiting high homology with the linA gene from S. paucimobilis, while a preliminary study also indicated strong homology among the two linB genes. All enzymes involved in the gamma-HCH degradative pathway appear to be extracellular and encoded by genes located on the chromosome, although numerous cryptic plasmids have been detected.

Amino Acid Sequence↗
PubMed1996

Outcome assessment in spinal infections.

The importance of outcome studies in patients undergoing spinal surgery is discussed. There are numerous questionnaires used to assess quality of life results in orthopedic patients. This suggests disagreement and difficulty in the assessing and comparing outcomes. Several of these instruments for assessing outcome are reviewed. Postoperative spinal infection can prolong a patients recovery from spinal surgery and exacerbate symptoms of lower back pain. A review of the authors' patients at 3 years follow-up suggests that outcome with postoperative infections was similar to other patients with low back pain undergoing fusion without postoperative infectious complications.

Follow-Up Studies↗
PubMed1996

Assessment of pseudarthrosis in pedicle screw fusion: a prospective study comparing plain radiographs, flexion/extension radiographs, CT scanning, and bone scintigraphy with operative findings.

Twenty-five consecutive patients who had previously undergone lumbar fusion using stainless steel pedicle screw instrumentation and complained of persistent, severe pain were identified for prospective study. All patients had been scheduled for hardware removal and fusion inspection. Studies to rule out pseudarthrosis included plain radiography, flexion and extension radiography, computed tomography, and bone scintigraphy. Each preoperative radiographic study was then evaluated in a blinded fashion by a single independent radiologist and was determined to show fusion or pseudarthrosis. Each patient then underwent surgery, at which time the pedicle screw instrumentation was removed and the fusion was inspected. Using surgical inspection as absolute evidence of fusion or pseudarthrosis, statistical analysis was undertaken to evaluate the predictive value of the radiographic studies singly and in combination. No statistically significant correlation was found.

Bone Screws↗
PubMed1996

Outcome after Wiltse pedicle screw removal.

Thirty-five patients were retrospectively reviewed after hardware removal after previous posterior lumbar spinal fusion by using Wiltse pedicle screw fixation. Pseudarthrosis was intraoperatively confirmed in 10 patients. Thirty of 35 patients were reviewed at an average of 17.5 months (range, 6-57 months). Of 30 patients, 30 had persistent back pain that limited activities and lumbar motion. Patients found to have pseudarthroses were significantly more likely to have less pain, use fewer narcotic medications, and have an improved quality of life after reoperation than patients found to have solid fusions. Postsurgical assessment of fusion is difficult, with instrumentation making exploration the most reliable method determining the state of arthrodesis. Accurate preoperative assessment of the fusion mass is the most important factor in deciding whether or not to reoperate on patients after Wiltse pedicle screw arthrodesis of the lumbar spine.

Adult↗
PubMed1996

Evaluation of continuous intraspinal narcotic analgesia for chronic pain from benign causes.

Intraspinal narcotic analgesia (INA) has been used for chronic pain from nonmalignant causes with moderate success. To ascertain the efficacy of the morphine pump, we reviewed the 2-year results of continuous INA in 18 patients with failed back syndrome or arachnoiditis and intractable, debilitating pain that was unrelieved by conventional means. All patients underwent a trial screening of single-dose intrathecal narcotics with good pain relief. After 2 years, 8 pumps were still functioning, 8 patients had the pump removed or turned off, and 2 patients were lost to follow-up. Our patients averaged 1.4 additional procedures or hospitalizations after initial pump insertion. Overall, only 4 patients had objective evidence of benefit from INA, for a success rate of 25%. Results of this review suggest INA should not be used for the long-term management of chronic pain from nonmalignant causes.

Analgesia, Epidural↗
PubMed1995

Light-induced expression of ipt from Agrobacterium tumefaciens results in cytokinin accumulation and osmotic stress symptoms in transgenic tobacco.

Cytokinins are plant growth regulators that induce shoot formation, inhibit senescence and root growth. Experiments with hydroponically grown tobacco plants, however, indicated that exogenously applied cytokinin led to the accumulation of proline and osmotin. These responses were also associated with environmental stress reactions, such as salt stress, in many plant species. To test whether increased endogenous cytokinin accumulation led to NaCl stress symptoms, the gene ipt from Agrobacterium tumefaciens, encoding isopentenyl transferase, was transformed into Nicotiana tabacum cv. SR-1 under the control of the light-inducible rbcS-3A promoter from pea. In high light (300 mumol PPFD m-2 s-1), ipt mRNA was detected and zeatin/zeatin glucoside levels were 10-fold higher than in control plants or when transformants were grown in low light (30 mumol PPFD m-2 s-1). High light treatment was accompanied by increased levels of proline and osmotin when compared to low light grown transformed and untransformed control plants. Elevated in planta cytokinin levels induced responses also stimulated by salt stress, suggesting either common or overlapping signaling pathways are initiated independently by cytokinin and NaCl, setting in motion gene expression normally elicited by developmental processes such as flowering or environmental stress.

Adenine↗
PubMed1995

Syphilis in the South: rural rates surpass urban rates in North Carolina.

We studied primary and secondary syphilis rates in North Carolina for 1985 through 1993 to elucidate demographic trends and the role of rurality in the state's high rates. Each of the state's 100 counties was classified by rural-urban character; and county-level rates, adjusted for gender, race, and age group, were compared. Syphilis rates rose dramatically during the 9-year period, with most of the increase occurring among women, non-Whites, and rural counties. The rural rates recently surpassed urban rates, with the greatest increase experienced by non-White rural women. The exchange of sex for drugs and characteristics of rural poverty may be fueling these trends.

Adolescent↗
PubMed1993

An in vivo approach to define the role of the LCM, the key polypeptide of cyanobacterial phycobilisomes.

In cyanobacteria, phycobilisomes are regularly arrayed on the surface of the photosynthetic membranes, and their role is to funnel light energy to the underlying photosystem II reaction center. A model has recently been proposed that ascribes to the so-called LCM, a central role in the building up of the phycobilisome, in addition to its role of terminal energy acceptor (Capuano, V., Braux, A.-S., Tandeau de Marsac, N., and Houmard, J. (1991) J. Biol. Chem. 266, 7239-7247). The phycobilisomes of Calothrix sp. PCC 7601 are typically of the type found in most cyanobacteria. Those of Synechococcus PCC 7942 (or PCC 6301) differ in having central cores made up of two instead of three cylinders. We have integrated the Calothrix PCC 7601 apcE gene that encodes the LCM into the chromosome of a Synechococcus PCC 7942 strain. We have observed that the heterologous gene is expressed and that the corresponding product carries a bilin-type chromophore and can be detected in the phycobilisome fraction of the Synechococcus strain. Moreover, it is shown that, in agreement with our model, this LCM can direct the formation of phycobilisomes that have three-cylinder cores.

Bacterial Proteins↗
PubMed1993

Cytomegalovirus recurrence in seropositive pregnant women attending obstetric clinics.

To understand reasons for cytomegalovirus (CMV) recurrence, a cohort of 350 CMV-seropositive pregnant women attending obstetric clinics in Taiwan was examined for cervical or urinary CMV shedding. Urine specimens were collected from 350 women and cervical secretion specimens were collected from 220 women. We measured the association of various factors with CMV recurrence, which was defined as viral shedding identified by the presence of a CMV-specific gene sequence amplified by the polymerase chain reaction in seropositive individuals. CMV recurrence status was independently associated with a sexual activity composite variable, which was defined by three sexual activity indicators: age at first sexual intercourse, total years of sexual experience, and average frequency of sexual intercourse prior to pregnancy. Pregnant women with a history of genital tract infection were more likely than women without such history to experience cervical CMV recurrence. Similarly, pregnant women with previous urinary tract infections were more likely to experience urinary CMV recurrence. The findings indicate that multiple exposure to CMV by sexual activity prior to pregnancy is an important determinant of CMV recurrence during pregnancy.

Antibodies, Viral↗