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Biomedical subjects

P Robertson

Publications and source records attributed to P Robertson.

At least 55 records · Page 3Linked to original sources
PubMed1994

Decay of transplacental human immunodeficiency virus type 1 antibodies in neonates and infants.

Transplacental human immunodeficiency virus (HIV) antibodies from 11 uninfected and 3 infected infants of HIV-seropositive mothers were measured using end point titration of twofold dilutions of sera by a particle-agglutination method. Four or more sequential serum samples from each infant were collected between birth and age > or = 14 months and analyzed. Linear regression of log2 antibody titers of uninfected infants plotted against age (days) showed an exponential decay in maternal HIV antibodies. The mean half-life of passive HIV antibodies was 23.1 +/- SD 4.2 days (range, 18.2-29.3; 95% confidence interval, 20.2-26.0). The median age of clearance of maternal HIV antibodies was 13.3 months (range, 10.4-15.6). A model assuming first-order exponential decay and production of HIV antibodies was fitted to the time course of antibody titers of the infected infants. Minimal titers in each infected infant occurred at 5.5, 4.9, and 4.0 months, and doubling times of HIV antibodies from that point ranged from 16.8 to 31.4 days.

Agglutination Tests↗
PubMed1994

Early detection of human immunodeficiency virus type 1 infection in Australian infants at risk of perinatal infection and factors affecting transmission.

The earliest, most reliable methods for detecting human immunodeficiency virus type 1 (HIV-1) infection in infants at risk of perinatal HIV-1 and risks for transmission were investigated. Fifteen infants were followed prospectively from birth to age 21 to 48 months. Epidemiologic data on mothers during pregnancy were documented, and maternal proviral load (by quantitative polymerase chain reaction) and viral phenotype by HIV isolation were performed. Infants were assessed clinically and HIV isolation, HIV p24 antigen, polymerase chain reaction and total serum immunoglobulin determinations were performed. Four infants were infected. HIV isolation, HIV p24 antigen and polymerase chain reaction were positive within 3 months in all infected infants (100% sensitivity). False positive rates for a single test were 18, 9 and 9%, respectively. Median age of clearance of maternal antibodies was 13.4 +/- 2.1 months. Serum immunoglobulin G was significantly elevated after 6 months in all 4 infected infants. Advanced maternal age (> or = 30 years; Fisher's exact test, P > 0.014) was associated with transmission. A trend in higher maternal viral burden was observed among transmitters. Non-syncytium-inducing phenotype was present initially in all transmitting mothers.

Analysis of Variance↗
PubMed1994

Assessment of self-report in HIV surveillance: a pilot study.

The basis of HIV exposure category classification was investigated among selected cases of newly diagnosed HIV infection. Questionnaires seeking specific information on patient-reported exposure to HIV were forwarded to doctors who had requested the HIV antibody test for patients who met the study sample criteria. The cases of interest were those newly diagnosed between 1 January and 31 October 1991 and notified to state and territory health authorities as having been attributed to exposures to HIV other than male homosexual contact or receipt of blood, blood products or tissue. A total of 158 questionnaires was forwarded and 59 per cent were returned. Among the returned questionnaires included in the study sample, exposure to HIV on the original notification to the health authority was given as injecting drug use (8 per cent, 3 of 37), heterosexual contact (46 per cent, 17 of 37), or unavailable (46 per cent, 17 of 37). A clear basis for HIV exposure category classification was provided on the questionnaires for 70 per cent (7 of 10) of cases among women, whereas among men whose infection was attributed to heterosexual contact, a basis for exposure category classification was specified for only 43 per cent (10 of 23) of cases. Although the study was limited by the low response rate, use of the questionnaire provided a relatively simple means for assessing self-reported HIV exposure history.

Adolescent↗
PubMed1994

Screening and monitoring coeliac disease: multicentre trial of a new serum antibody test kit.

A multicentre trial was conducted to evaluate a new test for anti-gliadin antibodies (AGA) in serum (Coeliac Screening Kit, CSK, Medical Innovations Limited, Artarmon, NSW, Australia). The test showed excellent reproducibility for both anti-gliadin IgA and IgG detection. The average intraassay coefficient of variation (CV) was 3.0% for IgA and 2.4% for IgG (n = 6), while the average interassay CV was 6.4% for IgA and 4.3% for IgG (n = 3). By defining a positive test as both IgA and IgG elevated, a sensitivity of 93% in untreated coeliacs (n = 75) was observed. The corresponding specificities in healthy adults (n = 130) and healthy children (n = 77) were > 99% and 100% respectively, while in patients with other gastrointestinal disorders (disease controls) the specificity was 94% (n = 129). The test was also useful in monitoring patients, with anti-gliadin IgA and IgG falling for up to a year after commencing a gluten-free diet (GFD) (12 adults). In some patients however, antibody levels did not reach the normal cutpoint after many months on a GFD, which may reflect the patients' poor adherence to their gluten free diet. The test was superior to the Pharmacia anti-gliadin ELISA, and should be useful as an aid to the diagnosis of coeliac disease, as well as in the follow-up of treated patients.

Adult↗
PubMed1993

High-performance liquid chromatographic assay for two rifamycin-derived hypocholesterolemic agents in liver and biological fluids.

CGP 43371 (compound I), a mono-pivaloyl oxazole derivative of a 3-piperazino-rifamycin, has been in clinical trials as a potential hypocholesterolemic agent. A reversed-phase high-performance liquid chromatographic (HPLC) assay was developed using a C18 column and a gradient solvent system of methanol-0.1 M sodium acetate, pH 4.5, at a flow-rate of 1 ml/min. The compound and internal standard (rifampicin) were detected by their ultraviolet absorption at 254 nm. Isolation of the compounds from plasma and liver homogenates was accomplished by precipitation of proteins with acetonitrile, followed by evaporation under nitrogen and reconstitution in methanol. Bile, lymph and urine were injected onto the HPLC column without pretreatment. Calibration curves were linear (r > 0.999) over the concentration range 0.25-20.0 micrograms/ml. The assay procedure was also applicable to other rifamycin derivatives and was able to distinguish between molecular species containing small differences in functionality.

Animals↗
PubMed1991

Effects of pancreas transplantation on postprandial glucose metabolism.

BACKGROUND: Because a pancreas allograft is placed in the pelvis, pancreas transplantation abolishes the normal gradient between portal-vein and peripheral-vein insulin concentrations and causes systemic hyperinsulinemia. Whether pancreas transplantation restores carbohydrate metabolism to normal is not known. METHODS: We studied seven patients with insulin-dependent diabetes mellitus after pancreas-kidney transplantation, seven nondiabetic patients after kidney transplantation (to control for immunosuppression), and eight normal subjects. Measurements were made after an overnight fast and after ingestion of a mixed meal. RESULTS: Although plasma glucose concentrations did not differ in the two transplant groups, plasma insulin concentrations were significantly higher in the diabetic pancreas-kidney recipients than in the nondiabetic kidney recipients, both before the meal (mean +/- SE, 102 +/- 15 vs. 53 +/- 6 pmol per liter; P less than 0.05) and afterward (123 +/- 22 vs. 61 +/- 6 nmol per liter per six hours; P less than 0.05). Plasma C-peptide concentrations were the same in both groups, indicating that hyperinsulinemia was due to decreased insulin clearance rather than increased insulin secretion. Despite drainage of the venous effluent from the transplanted pancreas into the systemic circulation, the values for splanchnic clearance of ingested glucose, suppression of hepatic glucose release, incorporation of carbon dioxide into glucose, stimulation of glucose oxidation, glucose uptake, and forearm glucose clearance were all similar in the transplant groups and differed minimally from the values in the normal group. The similar rates of glucose uptake in the presence of higher systemic insulin concentrations indicated that the extrahepatic tissues of the diabetic pancreas-kidney recipients were insulin-resistant. CONCLUSIONS: Despite systemic delivery of insulin, pancreas-kidney transplantation in patients with diabetes results in carbohydrate metabolism similar to that in nondiabetic subjects receiving the same immunosuppressive agents after kidney transplantation.

Adult↗
PubMed1991

Perceptions of follow-up care in women with breast cancer.

One hundred one patients with breast cancer, 48 localized and 53 metastatic, were questioned about their perceptions of follow-up examinations. Patients with metastatic disease preferred more frequent follow-up. Most indicated that they wanted their physicians to ask them about pain and nutritional status at each follow-up visit and were aware of the tests they had received. Only a third of the patients recognized the value of the history in detecting recurrence, and two-thirds felt that the physical examination was helpful. Laboratory tests and imaging procedures were rated higher than the history in detecting recurrence. Most patients were unaware of the implications of a normal procedure or test and perceived "normal" as meaning an absence of cancer cells in the organ evaluated. Knowledge of the value and limitations of testing was not related to educational level or disease stage. Patients need to be educated about the effectiveness of follow-up examination. Greater emphasis should be placed on the history and physical examination, and the limitations of more costly laboratory and imaging procedures should be explained carefully.

Adult↗
PubMed1991

Operative and assisted delivery.

Decisions about the role of cesarean section, forceps, and vacuum delivery in obstetrics continue to be a challenging part of daily obstetric practice. Five interesting papers on this topic are reviewed, including a comparison of international rates of cesarean sections and vaginal births after cesarean section, the method of choice for the delivery of the low-birth-weight fetus presenting as vertex, the advantages of a prelabor cesarean section for a fetus diagnosed with meningomyelocele, and the appropriate role for the midforceps delivery in the 1990s.

Cesarean Section↗
PubMed1990

Smokeless tobacco use and health effects among baseball players.

The effects of smokeless tobacco (ST) use were studied in 1109 members of major and minor league professional baseball teams during spring training in 1988. The prevalence of current ST use was 39%. The median age at initiation among users was 18 years, and the median duration of use was 5 years. Among users, 75% cited a snuff brand as their usual ST product. Oral leukoplakia was present in 46% (196/423) of current-week ST users and 1.4% (7/493) of nonusers (odds ratio, 60; 95% confidence interval, 28 to 130). Prevalence of oral leukoplakia among ST users increased with hours used per day and decreased with time lapsed since last use, and was higher in snuff users than in chewing tobacco users. Of the subjects with oral leukoplakia who underwent punch biopsy, 91 had benign hyperkeratosis and one had mild dysplasia. Overall prevalence of dental caries, gingivitis, and plaque did not differ between ST users and nonusers. In analyses confined to facial surfaces of mandibular incisor teeth, where ST is most commonly used, there were significant increases among users in both gingival recession and attachment loss. Users of ST did not differ from nonusers in blood pressure, pulse, total or high-density lipoprotein cholesterol level, or white blood cell count, but among users high-density lipoprotein cholesterol levels were inversely associated with serum cotinine levels. The major health effects of ST use among professional baseball players are oral leukoplakia and localized periodontal disease. The study population was young, physically fit, and characterized by relatively moderate short-term ST use.

Adolescent↗
PubMed1990

Insulin-dependent diabetes mellitus: a risk factor in anorexia nervosa or bulimia nervosa? An empirical study of 116 women.

A number of recent studies suggest that diabetes mellitus confers a high risk for the development of anorexia nervosa or bulimia nervosa. In order to test this hypothesis, 56 women with IDDM and 60 non-diabetic female controls were studied. All subjects completed the Eating Attitudes Test (EAT), and the Bulimic Investigatory Test, Edinburgh (BITE). The subjects were interviewed in order to obtain clinical and demographic information as well as to determine test validity. The DSM-III-R criteria of anorexia nervosa and bulimia nervosa were used. Four items were removed from the original EAT in order to eliminate possible bias related to IDDM. The results did not support the hypothesis that eating disturbances occur more frequently in IDDM-patients. Six criteria are proposed to improve the methodological standards of future studies in order to facilitate comparison of results.

Adolescent↗
PubMed1990

Isotype responses of infected, virus-vaccinated and peptide-vaccinated cattle to foot-and-mouth disease virus.

An ELISA to measure bovine serum immunoglobulin isotypes (IgG1, IgG2, IgM and IgA) specific for foot-and-mouth disease virus (FMDV) or for synthetic FMDV peptides is described. Sera from cattle infected by FMDV, vaccinated with conventional inactivated virus vaccines or vaccinated with synthetic peptides were examined using this assay. Generally IgG subclasses dominated the antibody responses of all groups after an early IgM response had waned. An exception to this pattern was seen in the case of a group of immature calves given multiple or high doses of synthetic peptide and in which levels of IgM continued to rise until the end of the experimental period. Both infected animals and those vaccinated with inactivated virus mounted antibody responses in which IgG1 titres tended to predominate over those of IgG2. In some infected animals, an early IgG2 response was evident but resolution of lesions and clinical recovery did not occur until IgG1 antibody appeared in the serum some days later. In synthetic-peptide immunized animals the response was more variable but IgG1:IgG2 ratios at 21 days postvaccination were significantly lower than those of virus-vaccinated animals. It is proposed that differences in the isotype profiles induced by conventional FMD vaccines and those resulting from vaccination of cattle with synthetic FMDV peptides may in part account for the lower protective index of peptide-induced antibodies.

Animals↗
PubMed1990

A comparison of different sources of information about pregnancy and childbirth.

Different methods of obtaining information in medical and social research present problems of interpretation for the researcher. However, there are few systematic studies on the extent of the lack of concordance yielded by different methods. This paper uses data from a randomized controlled trial of social support in pregnancy to examine this issue in relation to three methods of data collection--medical records, home interviews and a postal questionnaire--on the following topics: obstetric history; smoking, alcohol use, number of antenatal hospital visits, bleeding and depression in pregnancy; length of labour; baby's sex, birthweight and neonatal health problems; and ethnicity. Considerable discrepancies are found comparing the different data sources. These suggest that mothers may be more reliable sources of information than medical records, and that the anonymity of a postal questionnaire may provide higher estimates than home interviews on some sensitive topics, such as smoking in pregnancy.

Data Collection↗
PubMed1990

A pilot study of intralymphatic interleukin-2. II. Clinical and biological effects.

Interleukin-2 (recombinant methionyl human interleukin-2 alanine 125; IL-2) was administered intralymphatically to 12 patients with advanced cancer in a phase I trial. Doses were administered once a week for 6 weeks in a dosage escalation schedule; patients were entered in four groups at successively higher starting dosages. Toxicity occurred in a profile similar to that seen with intravenous IL-2. The maximum tolerated dose with this route/schedule was 275,000 units/kg, a figure not higher than expected with intravenous administration. T1/2 alpha was prolonged to 54 min from the 13 min figure we obtained with IL-2 given intravenously. Granulocytosis and eosinophilia were seen, along with lymphocytosis following initial lymphopenia. Anti-IL-2 antibodies were seen in 42% of patients (compared to 16% with this agent given intravenously), suggesting increased immunogenicity of this route/schedule. No clinical response was achieved. Immunologic effects will be reported separately but are summarized.

Adolescent↗
PubMed1989

Purification and characterisation of NAD-glutamate dehydrogenase from Aspergillus nidulans.

NAD-Glutamate dehydrogenase has been purified from mycelia of A. nidulans. The enzyme comprises subunits of 110 kDa. It is located in the cytosol. It is completely denatured by 1.0 M guanidine hydrochloride, and is not renatured by subsequent dilution. Isophthalate is a strong competitive inhibitor and the enzyme is also inhibited by thiol reagents. The properties of the enzyme were compared to those from other fungi in terms of size, sensitivity to inhibitors, intracellular distribution and mode of regulation, and were found to resemble most closely those of Neurospora crassa.

Aspergillus nidulans↗
PubMed1989

Cardiac abnormalities in the fragile X syndrome.

Twenty three patients with fragile X syndrome underwent cardiovascular assessment. Echocardiography showed dilatation of the aortic root in 12 (52%) and mitral valve prolapse in five (22%), four of whom had an apical mid-systolic click on auscultation. Patients with fragile X syndrome have cardiac defects similar to those seen in other disorders of connective tissue such as Marfan's syndrome and Ehlers-Danlos syndrome. These, and other somatic features, suggest an underlying connective tissue dysplasia.

Adolescent↗