Search PubMed⌕ Search

Biomedical subjects

G Roberts

Publications and source records attributed to G Roberts.

At least 145 records · Page 8Linked to original sources
PubMed1991

Spectrum of in vitro antifungal activity of ditiocarb sodium.

The immunomodulator ditiocarb sodium (sodium diethyldithiocarbamate, DTC, CAS 148-18-5) is finding increasing use in treating AIDS-patients. Using a macro broth dilution method the minimal inhibitory concentrations and minimal fungicidal concentrations of DTC were studied for 76 fungal strains (54 species) and a broad spectrum of direct antifungal activity was found. All 6 Candida albicans strains tested were inhibited by 1.2 micrograms DTC/ml, a concentration achievable by i.v. administration of DTC in doses as presently used for immunomodulation. All strains of Cryptococcus were inhibited by DTC in concentrations of 2.5 micrograms/ml. In combination with amphotericin B, DTC showed a synergistic mode of action for 6 out of 7 Cryptococcus neoformans strains (checkerboard technique). As far as the direct antifungal activity of DTC was tested (11 strains, 5 species), the combination with amphotericin B or flucytosine showed no antagonistic mode of action. The augmentation of host defences by the immunomodulating agent DTC could become an adjunct to conventional therapy in immunocompromised patients with systemic fungal infections.

Amphotericin B↗
PubMed1991

Basal and stimulated plasma atrial natriuretic factor in type 2 diabetes.

Subjects with Type 2 diabetes have been reported to have elevated total exchangeable sodium when compared with normal subjects. Sodium retention may contribute to the development of hypertension in these subjects. Atrial natriuretic factor may play a role in sodium and blood pressure homeostasis in Type 2 diabetes. We have studied plasma atrial natriuretic factor in 17 subjects with Type 2 diabetes (9M:8F; aged 49 +/- 2 years) (mean +/- SE) and in 17 age- (49 +/- 2 years) and sex-matched controls. Mean fasting blood sugar was 8.3 +/- 0.6 mmol l-1 in the diabetic subjects. After fasting from 2200h, subjects remained upright from 0745h until 0945h when blood was taken for plasma atrial natriuretic factor, plasma renin activity and serum aldosterone. Two litres of 0.15 mmol l-1 NaCl was infused intravenously between 1000h and 1400h while the subjects remained supine. Blood was taken hourly. At 0945h plasma atrial natriuretic factor was 3.8 +/- 0.4 pmol l-1 in diabetic subjects and 6.1 +/- 1.6 pmol l-1 in controls (NS), at 1000h after 15 mins supine 3.5 +/- 0.3 and 7.9 +/- 2.3 pmol l-1 respectively (p < 0.05) and increased to 9.4 +/- 1.5 and 9.4 +/- 1.2 pmol l-1 in diabetic subjects and controls at 1400h (NS; both p < 0.01 vs basal values). Serum aldosterone, plasma renin activity, blood pressure and urinary sodium output for 12h before, 4h during and 8h after the NaCl infusion were not different between groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Aldosterone↗
PubMed1991

Serodiagnosis of echinococcosis: evaluation of two reference laboratories.

Two reference laboratories (CDC, Atlanta, and Institute of Hygiene, Vienna) were evaluated for their ability to diagnose echinococcosis from single serum-specimens by serological assays. Out of 18 specimens, both laboratories correctly identified the 12 sera from patients with echinococcosis. Each laboratory was able to give the species diagnosis for 11 of 12 cases. The CDC abstained from giving a final species-diagnosis for a serum from a patient with alveolar echinococcosis, the Institute of Hygiene similarly, for a case of cystic echinococcosis. Our findings reveal the considerable potential of today's serological methods for primary diagnosis of infections with Echinococcus granulosus and Echinococcus multilocularis.

Adult↗
PubMed1990

Prevalence of different types of lysosomal storage diseases in Saudi Arabia.

The frequency of different types of lysosomal storage diseases in 125 referred cases, collected over three years, was compared to the occurrence elsewhere. The data suggest that mucopolysaccharidosis (MPS) type IVA (Morquio disease), multiple sulphatase deficiency, Niemann-Pick disease type B, GM2 gangliosidosis type '0' (Sandhoff disease), and ceroid lipofuscinosis (Jansky-Bielschowsky and Batten-Spielmeyer-Vogt syndromes) are encountered frequently in Saudi Arabia, as compared to other storage diseases. In contrast, some other diseases such as the adult variant of Gaucher's disease were not observed. Half of the GM2 gangliosidosis type '0' cases originated from one large tribe in the country. Other conditions did not show tribal predilection. The ceroid lipofuscinosis cases in Saudi Arabia originated from four large families. Consanguineous marriages taking place within tribal boundaries probably account for the pattern observed.

Child, Preschool↗
PubMed1990

Investigation of expression of 5T4 antigen in cervical cancer.

A monoclonal antibody detecting amniotrophoblastic antigen 5T4 has shown reactivity against various neoplastic cell lines and tumour specimens but with a relatively restricted normal tissue expression. This antibody has been investigated as a potential indicator of premalignant changes identified as cervical intra-epithelial neoplasia and malignant cervical lesions using immunohistochemistry on frozen tissue biopsies. The basal cells of normal cervical stratified epithelium exhibited faint staining, but a general increase in intensity and extent of specific labeling of this tissue was seen from the first premalignant stage through to carcinoma. In most cases, this was in accordance with the distribution of dysplastic cells, and was accompanied by increased specific staining of the stromal tissue. All invasive squamous carcinomas of the cervix were 5T4 antigen positive. Common inflammatory non-malignant diseases did show a certain degree of epithelial and stromal reactivity. These results, showing 5T4 reactivity with neoplastic and pre-neoplastic lesions, may provide a quantitative basis for its potential use as a tumour marker in the immunochemical detection on immunoassay of cervical cancer.

Antigens, Neoplasm↗
PubMed1990

Clinical presentation and investigation of patients proceeding to isotope lung scanning for suspected pulmonary embolism.

The presenting features of 250 consecutive patients who underwent a ventilation/perfusion lung scan for suspected pulmonary embolus (PE) were analysed. Ninety-six patients had lung scans highly suggestive of PE, with one or more unmatched segmental perfusion defects (scan positive), 86 had low probability scans (scan negative) and 68 an indeterminate scan. Scan positive patients were more likely to have a PaO2 of less than 10.7 kPa, an elevated P(A-a)O2 and an abnormal chest X-ray compared with scan negative patients but these measurements were of poor specificity. Furthermore, scan-positive patients had a higher incidence of lung disease. Localized chest wall tenderness was more common in scan-positive patients, occurring in 9% of patients, but there were no other significant differences in individual symptoms, signs or electrocardiographic findings between scan-positive and scan-negative patients. The diagnosis of PE should not be made on clinical grounds alone and all patients suspected of having a PE should at least undergo isotope lung scanning.

Adolescent↗
PubMed1990

Plasma atrial natriuretic factor levels during normal pregnancy and pregnancy complicated by diabetes mellitus and hypertension.

Atrial natriuretic factor (ANF) may play a role in the regulation of the changes of blood volume and vascular reactivity during pregnancy and when pregnancy is complicated by hypertension. Reports of plasma ANF levels during pregnancy are conflicting. We have prospectively studied plasma ANF levels during pregnancy in 25 women, and compared these with 20 age-matched non-pregnant women. Five women developed hypertension during pregnancy and a further five who remained normotensive had insulin-dependent diabetes mellitus. Plasma ANF was 6.8 +/- 1.2 (mean +/- SEM) and 6.3 +/- 0.9 pmol/l during weeks 8-15 and 24-31 of normal pregnancy (n = 15; vs non-pregnant levels (4.0 +/- 0.6 pmol/l) P less than 0.05, n = 20). Levels were 4.3 +/- 0.8 and 3.9 +/- 0.4 pmol/l during weeks 16-23 and 32-39. In the diabetic patients and in the group who developed hypertension levels were at no time different from the uncomplicated pregnancy group. Serum aldosterone increased as pregnancy progressed, but plasma renin activity remained unchanged. As plasma ANF was not different between those who did, and those who did not develop hypertension, early measurement of it will not predict who will and who will not develop hypertension during pregnancy.

Adult↗
PubMed1990

The MMPI and Jesness Inventory as measures of effectiveness on an inpatient conduct disorders treatment unit.

There is a paucity of research on the effectiveness of inpatient treatment of conduct disorders. The purpose of the present study was to determine what effect a locked behavioral/cognitive treatment setting would have upon the Minnesota Multiphasic Personality Inventory (MMPI) and Jesness Inventory scores of adolescent inpatients. Fifty consecutive admissions (30 males, 20 females) to a conduct disorders unit were administered the MMPI and Jesness Inventory pre- and posttreatment. Statistically significant changes were found on both inventories. Males responded to treatment more favorably than did females. Improvement on the test scores could not conclusively be linked to the treatment due to the absence of a control group; however, combined with previous research, the results indicate areas of improvement in the sample's pathology.

Adolescent↗
PubMed1989

The role of physical and chemical characteristics in assessing the performance of a new biological vascular graft.

Information obtained from physical and chemical characterization of vascular grafts can prove valuable in obtaining a preliminary assessment of potential in vivo performance. The data presented illustrate the concept and show that the new biological graft made from bovine ureters has adequate performance characteristics for use as a potentially successful vascular graft.

Animals↗
PubMed1989

Role of thiol agents in protecting against the toxicity of helenalin in tumor-bearing mice.

Helanalin, a sesquiterpene lactone antineoplastic agent, is toxic at therapeutic doses in murine tumors. The toxicity has been assumed to be correlated with the binding of the drug to cellular thiol groups. Studies were undertaken to increase the intracellular level of GSH in the liver, kidney and other tissues to eliminate the toxicity of helenalin in vivo. Combination of helenalin 8 mg/kg/day i.p.) with L-cysteine (100 mg/kg/day), beta-mercaptoethanolamine (20 mg/kg/day), 18-beta-glycyrrhetinic acid (15 mg/kg/day), or 4,4'-diaminodiphenylsulfone (10 mg/kg/day) afforded improvement in survival of mice bearing P-388 lymphocytic leukemia. However, other thiol-elevating agents, anti-oxidants, intracellular buffering agents, and cardiac treatment drugs were not effective. Hydrocortisone, Cortef, treatment with helenalin afforded improvement in life expectancy. Reduced glutathione (GSH) and non-protein sulfhydryl (NPS) levels were not reduced in the liver, kidney, or circulating red blood cells (rbc) by helenalin treatment. After three days treatment of mice with helenalin, GSH levels were reduced and NPS levels elevated in P-388 tumor cells. Administration of L-cysteine, beta-mercaptoethanolamine, 4,4'-diaminodiphenylsulfone, or 18-beta-glycyrrhetinic acid alone caused no alteration in liver GSH but elevated NPS levels; P388 cell GSH and NPS levels were lowered. Combination of any of these agents, after three days, with helenalin afforded increases in P-388 cell GSH and NPS levels. This data would suggest that helenalin toxicity is not related to the lowering of GSH or NPS levels in critical tissues of mice.

Animals↗
PubMed1989

Basal and saline-stimulated levels of plasma atrial natriuretic factor in acromegaly.

We have studied plasma ANF before and after a 4-h intravenous infusion of normal saline in eight subjects with active acromegaly and in eight age and sex-matched control subjects. Plasma ANF, serum aldosterone and blood pressure were measured basally and after 2 and 4 h and plasma renin activity basally and after 4 h. Basal plasma ANF was similar in each group (4.4 +/- 1.5 pmol/l (mean +/- SEM) in acromegalic subjects and 5.3 +/- 0.7 pmol/l in controls NS). Plasma ANF did not rise significantly after saline in the acromegalic group (2-h value, 5.9 +/- 0.9; 4-h value, 5.1 +/- 0.9 pmol/l) but did rise significantly in the control group (2-h value, 8.9 +/- 1.9; 4-h value 9.5 +/- 1.3 pmol/l, both values P less than 0.05 vs basal level). The 4-h ANF value was significantly higher in the control group than in the acromegalic group (P less than 0.05). Basal and stimulated serum aldosterone values were similar in the two groups. Plasma renin activity suppressed to a lesser extent in the acromegalic group after 4 h. The facts that basal plasma ANF was not raised in acromegalic subjects and did not respond to saline stimulation demonstrate that an abnormality of ANF control may be an important factor in the aetiology of the expanded sodium status of patients with acromegaly and hence may contribute to the hypertension seen in patients with growth hormone excess.

Acromegaly↗
PubMed1989

The dmfs and dmft of young South African children.

As part of a series of frequent epidemiological field studies to determine caries prevalences in the primary dentition of young South African children, 1436 children of 1-4 yr of age from five ethnic groups were examined. Using WHO diagnostic criteria decayed, missing, and filled surfaces were determined with mirror and probe and caries free, dmfs, dfs, ds, mfs, and dmft scores were calculated. The investigation has shown that urban coloured and Indian children have the highest caries prevalences and urban white children have the lowest. It is suggested that the percentage of caries-free children should be used to set goals for reduction in caries.

Black or African American↗
PubMed1989

Variations in the plasma concentration of atrial natriuretic factor across 24 hours.

There is little information available concerning the presence or absence of a normal variation in the circulating concentration of atrial natriuretic hormone throughout a 24 h period. We have examined this in 8 normal subjects (aged 23-35 years) on a fixed 120 mmol Na+ diet. Circulating levels of ANH, plasma renin activity, serum aldosterone and serum cortisol were determined two-hourly during 24 h in a supine position. There was a significant change in the concentration of each of these four hormones during the study period (P less than 0.05). ANH: peak 8.5 (22.00 h), nadir 4.0 (12.00 h) (pmol/l); PRA: peak 1.7 (04.00 h), nadir 0.8 (22.00 h) (microgram.l-1.h-1); aldosterone: peak 350 (14.00 h), nadir 143 (22.00 h) (pmol/l); cortisol: peak 346 (08.00 h), nadir 51 (22.00 h) (nmol/l). Peak plasma ANH occurred at 22.00 h and with the exception of times 20.00 h and 10.00 h this value was significantly higher than all the other time means (P less than 0.05). The only other significant differences were between plasma ANH at 20.00 h and 06.00 h, 08.00 h, 12.00 h and 14.00 h, respectively (P less than 0.05). From midnight until 18.00 h, there was no significant difference between any of the time means. There was a peak in PRA at 04.00 h, while peak serum aldosterone and serum cortisol occurred at 14.00 h and 08.00 h, respectively. This study suggests that ANH may display a diurnal rhythm. Our findings provide further physiological evidence that plasma ANH and PRA may have a reciprocal relationship.

Adult↗
PubMed1989

Relationship between basal and sodium-stimulated plasma atrial natriuretic factor, age, sex and blood pressure in normal man.

The relationships between plasma atrial natriuretic factor (ANF), blood pressure (BP) and age have not been clearly defined. We measured plasma ANF levels and BP in 128 normal subjects (65 male; 63 female; mean age 48 years, range 20-87 years) on no medication. In subjects of 75 years or less (n = 120) plasma ANF was 5.7 +/- 0.3 pmol/l (mean +/- SEM). Plasma ANF did not differ between sexes (males 5.6 +/- 0.4 pmol/l, females 5.9 +/- 0.4 pmol/l). There was a positive correlation between plasma ANF and age, correlation coefficient (r) = 0.46, systolic BP (r = 0.44), diastolic BP (r = 0.22) and mean BP (r = 0.37) (all P less than 0.01), but after multiple linear regression analysis plasma ANF only related significantly (P less than 0.01) to age and systolic BP once other factors had been excluded. We also measured plasma ANF after erect and supine posture and during a 21IV normal saline infusion given over 4 hrs (n = 24; age range 21-62 years) after an overnight fast. Mean plasma ANF was 5.9 +/- 1.1 pmol/l erect, 7.4 +/- 1.6 pmol/l supine and rose to 10.1 +/- 1.4 pmol/l after saline (both P less than 0.05 vs basal). Response to saline was assessed as the area under the curve of hourly measurements. Neither this nor peak ANF during saline infusion correlated with age. We conclude that basal plasma ANF is influenced by age and systolic BP but plasma ANF response to acute saline stimulation is not.

Adult↗