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Biomedical subjects

J Todd

Publications and source records attributed to J Todd.

At least 127 records · Page 7Linked to original sources
PubMed1992

Prostitutes and their clients: a Gambian survey.

The social backgrounds and working behaviour of 248 prostitutes in urban and rural areas of The Gambia were investigated. Prostitutes were found to be highly mobile, moving frequently between a number of working locations in The Gambia and neighbouring Senegal, from which most of them originated. The educational level of prostitutes and the standard of living of their natal families were above average. Prostitutes worked on average four days a week and had between two and three clients a night. Condoms were used in up to 80% of contacts. 795 clients of prostitutes were interviewed and found to be on average of low educational and occupational status. Half were non-Gambian and most were currently travelling or living away from home.

Abortion, Therapeutic↗
PubMed1992

A novel semi-automated paramagnetic microparticle based enzyme immunoassay for hepatitis C virus: its application to serologic testing.

A new rapid serologic enzyme immunoassay for antibodies to hepatitis C virus (HCV) is described. The assay combines synthetic peptide and recombinant antigens representing putative structural and non structural HCV gene products with paramagnetic microparticle assay (MP assay) technology. Assay readout is based upon an enzymatically generated fluorescent product which is quantified with a novel semi-automated washer/reader instrument system. Assay sensitivity and specificity was determined to be greater than the first generation HCV C-100 EIA using a non-A, non-B hepatitis disease panel, an HCV performance panel, an HCV seroconversion panel, dilutions of HCV reactive sera, and random volunteer blood donor specimens.

Evaluation Studies as Topic↗
PubMed1992

Association between HIV-2 infection and genital ulcer diseases among male sexually transmitted disease patients in The Gambia.

OBJECTIVE: To investigate whether genital ulcer diseases are cofactors which enhance the transmission of HIV-2 in West Africa. DESIGN: A cross-sectional study of 435 men presenting with a sexually transmitted disease (STD). SETTING: The outpatient clinic of the Medical Research Council Laboratories, a primary care facility in Fajara, a suburb of Banjul, the capital city of The Gambia (West Africa). PATIENTS, PARTICIPANTS: Six hundred and twenty-four men presenting with a genital complaint, of whom 443 had an STD. Eight of the men with an STD were excluded from further analysis because they were HIV-1-infected (five patients) or had indeterminate Western blot patterns (three patients). The remaining 21 HIV-2-infected and 414 seronegative men constituted our study-group. MAIN OUTCOME MEASURES: Participants were questioned about previous STD and behavioural and demographic characteristics. A physical examination was performed and serum collected for measurement of antibodies against Haemophilus ducreyi and Treponema pallidum. RESULTS: HIV-2-infected men were more likely than HIV-seronegative participants to have previously had a genital ulcer [odds ratio (OR), 3.00; 95% confidence interval (Cl), 1.18-7.60] and to have antibodies against T. pallidum (OR, 5.95; 95% Cl, 2.10-16.91), or H. ducreyi (OR, 4.59; 95% Cl, 1.71-12.33). Circumcised patients with residual foreskin were more likely to be HIV-2 infected than patients with complete circumcision. HIV-2-seropositive patients were six times more likely to have generalized lymphadenopathy than their seronegative counterparts. CONCLUSIONS: Our data suggest that genital ulcerative diseases, such as syphilis and chancroid, are probably cofactors that increase the transmission of HIV-2 in West Africa, and that HIV-2 infection frequently results in generalized lymphadenopathy.

Adolescent↗
PubMed1992

Clinical and laboratory predictors of survival in Gambian patients with symptomatic HIV-1 or HIV-2 infection.

OBJECTIVES: To determine which clinical and immunological features of patients with symptomatic HIV-1 and HIV-2 infection best predict survival in The Gambia. METHODS: All patients presenting to two hospitals in The Gambia between January 1987 and June 1990 with symptoms or signs suggesting chronic HIV infection were tested for HIV-1 and HIV-2 antibodies. Eighteen HIV-1 and 31 HIV-2-infected patients were recruited to the study, investigated intensively on admission and followed up until the end of 1990. Presenting clinical features, such as Karnofsky score, diagnosis of AIDS according to World Health Organization Bangui or Centers for Disease Control criteria and number of associated infections, together with five immunological measurements, as well as type of HIV infection, were related to length of survival using proportional hazard models fitted to Kaplan-Meier plots of survival times. RESULTS: Karnofsky score and diagnosis of AIDS were the best clinical predictors of survival. Type of HIV infection or number of associated infections did not predict outcome. The most powerful laboratory predictors were log(e) serum neopterin level, CD4 cell count and log(e) serum beta 2-microglobulin (beta 2M) level. The estimated median survival times (90% confidence interval) of the HIV-1 and HIV-2-infected were six (4-11) and 13 (9-20) months, respectively. These survival times do not differ significantly. CONCLUSIONS: The Karnofsky score and measurements of serum neopterin or beta 2M, which are easier and cheaper to perform than CD4 counts, may prove to be useful guides to prognosis for HIV infection in Africa.

Acquired Immunodeficiency Syndrome↗
PubMed1992

Purification and partial characterization of a membrane-associated lipoxygenase in tomato fruit.

Membrane-associated lipoxygenase from green tomato (Lycopersicon esculentum L. cv Caruso) fruit has been purified 49-fold to a specific activity of 8.3 mumol.min(-1).mg(-1) of protein by solubilization of microsomal membranes with Triton X-100, followed by anion- exchange and size-exclusion chromatography. The apparent molecular mass of the enzyme was estimated to be 97 and 102 kD by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and size-exclusion chromatography, respectively. The purified membrane lipoxygenase preparation consisted of a single major band following sodium dodecyl sulfate-polyacrylamide gel electrophoresis, which cross-reacts with immunoserum raised against soluble soybean lipoxygenase 1. It has a pH optimum of 6.5, an apparent K(m) of 6.2 mum, and V(max) of 103. mumol.min(-1).mg(-1) of protein with linoleic acid as substrate. Corresponding values for the partially purified soluble lipoxygenase from tomato are 3.8 mum and 1.3 mumol.min(-1).mg(-1) of protein, respectively. Thus, the membrane-associated enzyme is kinetically distinguishable from its soluble counterpart. Sucrose density gradient fractionation of the isolated membranes indicated that the membrane-associated lipoxygenase sediments with thylakoids. A lipoxygenase band with a corresponding apparent mol wt of 97,000 was identified immunologically in sodium dodecyl sulfate-polyacrylamide gel electrophoresis-resolved proteins of purified thylakoids prepared from intact chloroplasts isolated from tomato leaves and fruit.

Journal Article↗
PubMed1992

Evaluation of a Treponema pallidum western immunoblot assay as a confirmatory test for syphilis.

Tests for the detection of antibodies to Treponema pallidum are recommended for the confirmation of reactive nontreponemal test results and the accurate diagnosis of syphilis. The present-day use of Western blot (immunoblot) technology for the diagnosis of retroviruses prompted the development and evaluation of a Western blot assay with whole-cell T. pallidum as the antigen. The assay detected antibodies in syphilitic serum or plasma from dilutions of specimens incubated overnight with test strips. A test was considered positive when at least three of four major antigens having molecular masses of 15.5, 17, 44.5, and 47 kDa were detected. The Western blot assay had 93.8% sensitivity and 100% specificity for clinically defined samples. The Western blot assay was compared with double-staining fluorescent treponemal antibody absorption [FTA-ABS (DS)], which had a sensitivity and a specificity of 91.7 and 92.0%, respectively. Dilution series studies of syphilis-positive specimens indicated that the Western blot assay has an endpoint of reactivity at least 3 to 4 serial dilutions greater than that for FTA-ABS (DS). Overall, the greater than 95% agreement between the Western blot assay and FTA-ABS (DS) for clinically defined specimens indicates that the sensitivity of the Western blot assay is equal to or greater than that of FTA-ABS (DS). The Western blot assay demonstrated no false-positive or equivocal reactivities for nonsyphilitic specimens, including normal specimens (both plasma and serum), biological false-positives, and specimens with elevated gamma globulin or antinuclear antibody. We conclude that the high sensitivity and specificity of the T. pallidum Western blot assay, together with its simplicity and objectivity, make it a good confirmatory test for syphilis.

Animals↗
PubMed1992

Immune response of cattle to Haemophilus somnus lipid A-protein conjugate vaccine and efficacy in a mouse abortion model.

Immunogenicity of the lipid A component of Haemophilus somnus lipooligosaccharide in cattle and mice was examined after purification, detoxification, and covalent conjugation to a protein carrier. After 2 inoculations, a substantial antibody response was induced in most cattle to lipid A and the protein carrier. To determine whether antibodies to lipid A would be protective, 5 x 10(7) colony-forming units of H somnus strain 649 were administered IV to endotoxin-responsive (C3H/HeN) mice. In one study, 8 of 13 C3H/HeN mice aborted when inoculated. In contrast, abortion did not result when mice were inoculated with the same dose of an isolate of H somnus normally found in the prepuce or with the rough mutant Escherichia coli J5. In addition, endotoxin-nonresponsive (C3H/HeJ) mice were significantly (P = 0.03) more resistant to abortion by strain 649 than were C3H/HeN mice, but inoculated C3H/HeN mice were only slightly more resistant to H somnus abortion, compared with control mice. Although a large antibody response to lipid A was detected, there was no significant difference in the immunized group between mice that aborted and mice that delivered normally. Thus, lipooligosaccharide and other properties of virulent H somnus strains may contribute to abortion in mice.

Abortion, Veterinary↗
PubMed1991

Characterization of a non-hemolytic mutant of Actinobacillus pleuropneumoniae serotype 5: role of the 110 kilodalton hemolysin in virulence and immunoprotection.

To determine the role of hemolysin(s) in virulence and immunoprotection, non-hemolytic mutants of Actinobacillus pleuropneumoniae serotype 5, strain J45, were isolated following chemical mutagenesis. One mutant was selected for extensive characterization. Differences in capsule content, or in lipopolysaccharide or membrane protein electrophoretic profiles of the parent and mutant were not detected. A predominant, calcium-inducible protein of 110 kDa was present in culture supernatant of the parent, but absent from the mutant. Two-dimensional (2-D) gel electrophoresis confirmed that the 110 kDa protein was absent in culture supernatant of the mutant, but few, if any, minor differences could be detected in whole-cell proteins between the parent and mutant. The mutant totally lacked extracellular hemolytic and cytotoxic activity. Lysates of whole cells of the mutant contained weak hemolytic activity, and the 110 kDa protein could be detected by immunoblotting. Neutralization titers were negative in pigs immunized with the mutant or purified, denatured hemolysin, although enzyme-immunoassay titers were detected. Four additional independently isolated non-hemolytic mutants were avirulent in pigs and mice at doses greater than 10 times the lethal dose of the parent. Neither pigs nor mice were protected against lethal infection following immunization with the non-hemolytic mutant. We conclude that the 110 kDa hemolysin plays an important role in bacterial virulence and the pathogenesis of pleuropneumonia, and that sufficiently high levels of neutralizing antibodies to the 110 kDa hemolysin may be required for protection of pigs against disease.

Actinobacillus↗
PubMed1991

Disseminated strongyloidiasis in AIDS: uncommon but important.

Disseminated Strongyloides stercoralis infection is a rare and severe but treatable complication of AIDS. We present a case where this infection was successfully treated and review the available literature. Cases may present many years after they have left an area endemic for Strongyloides infection, emphasizing the need for a full travel history. Symptoms are typically gastrointestinal and pulmonary, with infiltrates often seen on chest radiography. Diagnosis requires stool examination and biopsy of affected sites. Treatment with repeated courses of thiabendazole (25 mg/kg twice daily for 5 days) was successful in our case, but maintenance regimens have not yet been defined. The relative rarity of this complication of AIDS suggests that, where both infections are present, disseminated strongyloidiasis only arises either when HIV-induced immunodeficiency is profound or, possibly, when it is accompanied by impaired granulopoiesis.

Acquired Immunodeficiency Syndrome↗
PubMed1991

Genotypic identification of pathogenic Mycobacterium species by using a nonradioactive oligonucleotide probe.

Commercial DNA hybridization assays (Syngene, Inc., San Diego, Calif.) utilizing alkaline phosphatase-labeled oligonucleotide probes for the identification of Mycobacterium tuberculosis complex and M. avium complex (MAC) were evaluated with 261 isolates of mycobacteria. On the basis of biochemical criteria, the test for MAC was 98% specific and more sensitive (95 of 99, 95%) than Gen-Probe (88 of 99, 89% sensitivity); the major difference in sensitivity noted between the two systems was related to the hybridization of seven MAC strains to the SNAP X probe. The M. tuberculosis complex probe correctly identified all 62 isolates of M. tuberculosis and all 11 isolates of M. bovis, for a sensitivity of 100%. There were two discrepant reactions with mycobacteria other than M. tuberculosis complex isolates.

Bacteriological Techniques↗
PubMed1990

Estimation of serum V kappa IIIb light chains in rheumatoid arthritis and correlation with CD5-positive B-cells.

The presence of V kappa IIIb light chains in the sera of rheumatoid arthritis (RA) patients has been evaluated by an enzyme-linked immunosorbent assay (ELISA). V kappa IIIb light chains have been confirmed to be largely restricted to IgM, and were rarely detected in the IgG fraction of sera. The concentration of total serum V kappa IIIb did not significantly vary with age, nor did it correlate with IgM-rheumatoid factor (RF) titre. Although total serum V kappa IIIb was not significantly increased in RA patients compared with matched controls, IgM-RFs frequently contained V kappa IIIb. Using flow cytometry, CD5-positive B-cells were not increased in these RA patients compared with healthy laboratory control personnel. Furthermore, there was no direct correlation between total serum IgM V kappa IIIb content and CD5-positive B-cell numbers in peripheral blood.

Adult↗
PubMed1990

Detection of serotype-specific antibodies or capsular antigen of Actinobacillus pleuropneumoniae by a double-label radioimmunoassay.

Diagnostic tests for Actinobacillus pleuropneumoniae have been problematic because current tests do not use a purified antigen and in most cases measure either antibody or antigen, but not both. We describe a Farr-type double-label radioimmunoassay that utilizes purified, serotype-specific, 3H-capsule to measure antibody to capsule directly or that can measure capsule in a sample indirectly by inhibition of antibody binding. The assay could detect about 1 ng of serotype-specific antibody in serum or at least 100 pg of capsule in a sample. Due to the sensitivity of the assay, false-positive results were common with neat sera (probably due to cross-reacting antibodies to unrelated antigens), but the specificity was improved when the sera were diluted 1:100. The radioimmunoassay should prove to be a useful reference method for research and diagnostic testing and for comparison of new assays for detection of capsule or antibodies to capsule.

Actinobacillus↗
PubMed1989

Factors predicting the response of patients with advanced breast cancer to endocrine (Megace) therapy.

We have treated 238 patients with advanced breast cancer with megestrol acetate (Megace, Bristol-Myers): 221 were assessable for response at 6 months by UICC criteria. Thirty-six (16%) patients responded, 54 (25%) were static and 131 (59%) progressed. Survival from the time of starting Megace calculated by log-rank analysis showed no significant difference in survival between patients showing response and static disease at 6 months. Patients with progression of disease within 6 months survived significantly shorter than patients who showed response or static disease at 6 months. Categorizing response at 6 months appeared to identify patients who had static disease of worthwhile duration. ER status of the primary tumour correlated significantly with survival from the time of commencing Megace. However, when Megace was used as a second-line hormone therapy the assessment of response or static disease on prior hormone therapy was a better predictor of the effect of Megace than ER status of the primary tumour.

Adult↗
PubMed1989

The recurrence risks for mild idiopathic mental retardation.

A genetic study of children attending ESN(M) schools in Coventry has shown a recurrence risk of idiopathic mental retardation in sibs lying between 1 in 4 and 1 in 5. There was also a prevalence of mental retardation in other relatives that was greater than the population prevalence, and was less for second degree relatives than for first degree, and less still for third degree relatives. Recurrence in sibs was greater if more than one first degree relative was affected. There was no suggestion of a contribution by X linked genes, once the fragile X syndrome had been excluded. The presence of perinatal and other environmental factors in the index children did not alter the recurrence risk for sibs except for very low birth weight. There was a low recurrence rate of mental retardation in Asian families, suggesting that they had a different distribution of intelligence from non-Asian families.

Adolescent↗