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Biomedical subjects

D H Robertson

Publications and source records attributed to D H Robertson.

At least 37 records · Page 2Linked to original sources
PubMed1989

Screening for treponemal infection by a new enzyme immunoassay.

A new enzyme immunoassay (EIA, Captia Syphilis-G) for detecting IgG antibodies against Treponema pallidum was evaluated as a screening test for syphilis. When serum samples were tested at a dilution of 1 in 20 (EIA20), the overall agreement between the IgG EIA and serological status based on the T pallidum haemagglutination assay (TPHA) and the fluorescent treponemal antibody absorption (FTA-ABS) test was 99.2% (1310/1321). The sensitivity of the EIA20 was 98.4% (60/61) and the specificity 99.3% (1251/1260). Discrimination between patients with and without treponemal infection was good: the mean EIA20 absorbance ratios (patient/mean low titre positive control results) were 0.49 for antibody negative patients, 3.30 for patients with positive Venereal Diseases Research Laboratory (VDRL) test and TPHA results, and 1.77 for patients with negative VDRL but positive TPHA results. The cut off point for excluding treponemal infection was taken as 0.9. Specimens with ratios of more than 0.9 should be confirmed by the FTA-ABS test and evaluated for specific IgM antibodies to treponemes. When serum samples were tested at a 1 in 50 dilution (EIA50) the sensitivity was lower (80.3%) but the specificity was absolute. The reduction in sensitivity correlated with low absorbance ratios in the patients who were VDRL negative and TPHA positive. The screening performance of the IgG EIA20 is thus comparable with that provided by a combination of the VDRL test and TPHA. The potential for automation makes the EIA an attractive alternative, particularly in larger centres. Alternatively, the test can be performed at a 1 in 50 dilution (EIA50), at which level it is ideally suited for confirming the treponemal status of antibodies in serum samples preselected by positive cardiolipin antigen screening test results.

Antibodies, Bacterial↗
PubMed1988

Treatment failure in Trichomonas vaginalis infections in females. I. Concentrations of metronidazole in plasma and vaginal content during normal and high dosage.

Concurrent estimation by high pressure liquid chromatography (HPLC) of the concentrations of metronidazole in plasma and vaginal content in 12 patients with infections due to Trichomonas vaginalis who did not respond to normal and high-dose treatment has shown that the two levels are closely related to each other and to the dose. Individual idiosyncrasies in absorption of drug from the gut lumen or in its transfer into the vaginal content are unlikely to be the cause of treatment failure.

Adolescent↗
PubMed1988

Treatment failure in Trichomonas vaginalis infections in females. II. In-vitro estimation of the sensitivity of the organism to metronidazole.

We have developed a standard procedure to measure the susceptibility of Trichomonas vaginalis to metronidazole in vitro, by controlling the state of oxygenation of the test cultures, the size of the inocula in terms of infectivity, and providing multiple tests at each drug concentration. Estimates were made of the in-vitro sensitivity to metronidazole of T. vaginalis isolated from 11 randomly selected patients, all, except for three defaulters, known to have been treated successfully, and from six 'treatment failure' patients. Stocks isolated from 'successfully treated' patients, were all highly sensitive to metronidazole. Eighteen stocks isolated from the 'treatment failure' patients fell into two groups: (a) those clearly separable from sensitive stocks, with ED50 values (the concentration of drug at which growth is prevented in 50% of test wells) in N2 of up to 0.51 mg/l and 3.5 to 11 mg/l in N2/1%O2; (b) those giving intermediate ED50 values of up to 0.20 mg/l in N2 and 0.7 to 1.8 mg/l in N2/1%O2. The current procedure demonstrates clearly that repeated treatment failure in patients without other complication is associated with enhanced resistance to metronidazole of T. vaginalis, and it may discriminate between T. vaginalis infections that are likely to respond to higher dosage and those that are not.

Adult↗
PubMed1983

Ano-genital gonorrhoea and pharyngeal colonisation with meningococci: a serogroup analysis.

Among patients attending a clinic for sexually transmitted diseases, women without gonorrhoea were significantly less likely to be colonised with meningococci than were women with gonorrhoea, men with gonorrhoea and men without gonorrhoea: the respective carriage rates (per cent) for groupable plus non-groupable meningococci were 16, 26, 23 and 31. Considering groupable and non-groupable meningococci separately it was found that women without gonorrhoea were also significantly less likely to be colonised with groupable meningococci but there were no significant differences in the carriage rates of non-groupable meningococci. The association between ano-genital gonorrhoea and meningococcal colonisation of the pharynx observed previously with certain groups of patients most likely results from increased mouth-to-mouth contact in 'high-risk' patients rather than individual susceptibility to neisserial infection. The possibility that there is a difference in the predominant means of spread of groupable and non-groupable meningococci is discussed.

Anus Diseases↗
PubMed1983

Subarachnoid spinal analgesia. Changing patterns of practice.

The results of a postal enquiry into the current usage of subarachnoid spinal analgesia in Scotland are compared with those obtained in 1976. On each occasion replies were received from more than 70% of those consultants receiving questionnaires. Replies indicating use of the techniques increased from 40% in 1976 to 75% in 1981 and this was accompanied by an increase in the frequency of usage and a decline in medico-legal anxiety. While medical conditions retain their importance, the use of surgical procedures as primary indications has increased. The majority of consultants currently practising extradural techniques also use spinal methods, and there have been changes in attitude regarding the place and safety of both. There is continued minority dissatisfaction with the choice of spinal agents. No major neurological sequelae were reported and replies indicating that subarachnoid spinal analgesia had a useful place in practice increased from 80% in 1976 to more than 90% in 1981.

Anesthesia, Spinal↗
PubMed1982

Restriction endonuclease analysis of DNA from genital isolates of herpes simplex virus type 2.

High-resolution restriction endonuclease analysis of DNA from multiple herpes simplex virus type 2 isolates from 30 patients at a single clinical center has indicated that herpes simplex virus type 2 DNA sequences are highly conserved. However, the use of six endonucleases, EcoRI, BglII, HindIII, KpnI, BamHI, and SstI, established that each patient was infected by a unique virus. Comparison of virus isolates from the same patient show that the most sequence variation occurred in the terminal and subterminal BamHI fragments. The results suggest that each individual may induce specific variation in the herpes simplex virus type 2 genome and that the results of epidemiological studies based on restriction endonuclease analyses of herpes simplex virus type 2 DNA must be interpreted with care.

Base Sequence↗
PubMed1980

Effects of caffeine on plasma free fatty acids, urinary catecholamines, and drug binding.

The effects of caffeine (250 mg orally) on plasma free fatty acids (FFA), urinary catecholamines, and drug binding were studied in 16 normal subjects (six men, five women on oral contraceptives, and five women not on oral contraceptives). FFA doubled 1 hr after caffeine, and remained elevated for at least 4 hr. with elevation of each FFA. Urinary excretion of epinephrine and dopamine increased (p<0.05) in the first 2 hr. returning to baseline in the next 2 hr. Plasma binding of chlordiazepoxide, diaxepam, and propranolol was estimated in each of the hourly plasma samples after caffeine; there was no change in percent unbound drug in any of the samples. In vitro addition of oleic acid to plasma samples of four subjects caused a step-wise increase in percent unbound fraction of all three drugs whereas in vitro addition of caffeine did not further alter drug binding. In our study circulating plasma FFA and urinary catecholamine levels were elevated after caffeine ingestion. In spite of a rise in FFA, there was, however, no change in plasma binding of chlordiazepoxide, diazepam, or propranolol.

Blood Proteins↗
PubMed1980

Oropharyngeal flora and individual susceptibility to neisserial infection.

Beta-haemolytic streptococci were isolated from throat swabs from 49 (10.5%) of 466 patients undergoing cultural examination for gonorrhoea. Although beta-haemolytic streptococci were isolated more frequently from patients with genital or anorectal gonorrhoea (15.9%) than from those without (9.2%), the difference was not statistically significant. When groupable (A, B, C, or G) and other (non-A, -B, -C, or -G) beta-haemolytic streptococci were analysed separately, as statistically significant association between non-A, -B, -C, or -G streptococci and gonococci was observed but not between groupable beta-haemolytic streptococci and gonococci.

Female↗