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Biomedical subjects

P Robertson

Publications and source records attributed to P Robertson.

At least 19 recordsLinked to original sources
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↗
PubMed1989

Effects of methyl ethyl ketone pretreatment on hepatic mixed-function oxidase activity and on in vivo metabolism of n-hexane.

1. Male Fischer-344 rats were given methyl ethyl ketone (MEK; 1.87 ml/kg), a potentiator of the neurotoxicity of n-hexane, by gavage for 4 days prior to a single inhalation exposure to n-hexane (1000 ppm). 2. Samples of blood, liver, testis and sciatic nerve were obtained and analysed for n-hexane, MEK and their metabolites by g.l.c.-mass spectrometry. 3. Pretreatment with MEK increased the concentrations of 2,5-hexanedione (2,5-HD; the proximal neurotoxin) in blood, sciatic nerve and testis relative to concentrations in the tissues in sham-treated controls. 4. Concentrations of 2,5-dimethylfuran, a metabolite of 2,5-HD, were increased in all four tissues tested. 5. After 1-7 days treatment with MEK, the activity of 7-ethoxycoumarin O-deethylase was increased (up to 500%), but benzphetamine N-demethylase activity was virtually unaffected. 6. Hence, the potentiating effects of MEK on the neurotoxicity of n-hexane appear to arise, at least in part, from the activating effects of MEK on selected microsomal enzymes responsible for n-hexane activation.

Animals↗
PubMed1989

School and the in-center pediatric hemodialysis patient.

Life "on the machine" can significantly disrupt the social and academic school experience of preadolescent and adolescent renal failure patients because of their frequent absences. When hemodialysis patients were offered treatments after school and on Saturday mornings, patients, families, and staff reported significant improvement in the patients' social integration and academic performance.

Adaptation, Psychological↗
PubMed1988

Antibodies to HIV are produced within the central nervous system of all subjects with all categories of HIV infection.

Anti-HIV antibodies were found in the cerebrospinal fluid of all 41 subjects tested whose serum contained these antibodies. To ensure that locally produced antibody was being detected, a sensitive assay was used to demonstrate the integrity of the blood-brain barrier. Antibodies to ubiquitous adenovirus group antigens were sought, simultaneously, in CSF and serum. A lack of adenovirus antibodies in CSF of subjects seropositive for adenovirus was required before CSF anti-HIV antibodies could be considered to be produced within the central nervous system. Of the 41 subjects tested eight were asymptomatic, eight were clinically well but had persistent lymphadenopathy, 14 were immunodeficient and had constitutional symptoms (AIDS-related complex or ARC) and 11 had AIDS. Oligoclonal banding was detected in the CSF of 16 subjects and a pleocytosis was present in 24. Neither finding clustered with a particular stage of infection. It appears that HIV infection of T lymphocytes and the central nervous system occurs simultaneously, early in the course of the infection. All HIV infected subjects are at risk of developing primary neurological as well as immunological sequelae. Currently poorly understood resistance factors must protect both lymphocytes and nervous system tissue from damage by the HIV virus, as to date, the majority of infected subjects have not become immunodeficient or developed neurological disease.

AIDS-Related Complex↗