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Biomedical subjects

R Taylor

Publications and source records attributed to R Taylor.

At least 433 records · Page 24Linked to original sources
PubMed1991

Ethylene Biosynthesis-Inducing Endoxylanase Is Translocated through the Xylem of Nicotiana tabacum cv Xanthi Plants.

Ethylene biosynthesis-inducing xylanase (EIX) from the fungus Trichoderma viride elicits enhanced ethylene production and tissue necrosis in whole tobacco (Nicotiana tabacum cv Xanthi) plants at sites far removed from the point of EIX application when applied through a cut petiole. Symptoms develop in a specific pattern, which appears to be determined by the interconnections of the tobacco xylem. Based on results of tissue printing experiments, EIX enters the xylem of the stem from the point of application and rapidly moves up and down the stem, resulting in localized foliar symptoms on the treated side of the plant above and below the point of EIX application. The observation that a fungal protein that elicits plant defense responses can be translocated through the xylem suggests that plants respond to pathogen-derived extracellular proteins in tissues distant from the invading pathogen.

Journal Article↗
PubMed1991

Insulin action 1991.

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Endocrine System Diseases↗
PubMed1991

Peripheral and hepatic insulin sensitivity in healthy elderly human subjects.

Insulin resistance has been reported in normal ageing but discrepancies between such studies may be related to compounding factors such as body composition and exercise patterns. We employed a two-step hyperinsulinaemic euglycaemic clamp to assess peripheral and hepatic tissue insulin sensitivity and glucose recycling in 13 elderly (E) and 14 young (Y) healthy subjects controlling for the above factors. There was no difference in basal hepatic glucose production (E: 2.36 +/- 0.06, Y: 2.47 +/- 0.1 mg kg-1 min-1; P = 0.4). At step 1 (insulin infusion 15 mU kg-1 h-1) glucose turnover was similar (E: 2.65 +/- 0.13, Y: 2.88 +/- 0.22 mg kg-1 min-1; P = 0.4) but hepatic glucose production was lower in the elderly group (0.20 +/- 0.16 vs 0.64 +/- 0.10 mg kg-1 min-1; P = 0.03). At step 2 (insulin infusion 50 mU kg-1 h-1) glucose turnover was similar (E: 7.60 +/- 0.24, Y: 8.05 +/- 0.34 mg kg-1 min-1; P = 0.3) and hepatic glucose production was equal but negative (E: -1.35 +/- 0.18, Y: -1.34 +/- 0.22 mg kg-1 min-1; P = 0.9). Glucose recycling did not differ between the groups at any stage. Similar serum insulin levels were achieved in both groups at each step. Decreased glucose tolerance was confirmed in E with a higher 2 h blood glucose after an OGTT (5.3 +/- 0.4 vs 4.1 +/- 0.3 mmol l-1; P = 0.03) but incremental insulin response was similar (E: 3236 +/- 289, Y: 3586 +/- 463 mU l-1 min-1; P = 0.5). We conclude that changes in hepatic tissue insulin sensitivity do not cause the deterioration in glucose tolerance observed with age. A small reduction in both peripheral tissue insulin sensitivity and late insulin secretion may be responsible.

Adult↗
PubMed1991

The effect of sulphonylurea therapy on skeletal muscle glycogen synthase activity and insulin secretion in newly presenting type 2 (non-insulin-dependent) diabetic patients.

Ten newly presenting, Type 2 (non-insulin-dependent), Caucasian diabetic patients were studied before and after 8 weeks treatment with the sulphonylurea gliclazide, and in parallel 13 similar patients were studied before and after 8 weeks treatment with diet alone. Eight non-diabetic subjects were also studied. Insulin action was assessed by measuring activation of skeletal muscle glycogen synthase (GS) prior to and during a 4-h hyperinsulinaemic euglycaemic clamp (100 mU kg-1 h-1). Fasting plasma glucose (+/- SE) and glycosylated haemoglobin decreased to a greater extent in the gliclazide treated patients (fall of 6.2 +/- 0.7 vs 2.1 +/- 0.5 mmol l-1, p less than 0.005 and 4.7 +/- 0.5 vs 2.1 +/- 0.5%, p less than 0.005). This was accompanied by an increase in fasting serum insulin concentrations in the gliclazide treated patients (7.0 +/- 1.3 to 10.1 +/- 1.1 mU l-1, p less than 0.005), but no change in the diet treated patients. Fractional GS activity did not increase during the clamp at presentation in either treatment group (change +2.9 +/- 1.8 and -1.5 +/- 1.9%, respectively) whereas it increased markedly in the control subjects (+16.4 +/- 3.4%, both p less than 0.001). After 8-week treatment there was a significant increase in GS activity during the clamp in the patients receiving gliclazide (+6.9 +/- 2.7%, p less than 0.05), but no change in GS activity in the patients on diet alone (+0.5 +/- 1.4%). The difference in post-treatment muscle insulin action was significant (p less than 0.05). There was no correlation between the degree of improvement in metabolic control and the improvement in response of GS to insulin in the gliclazide treated patients (r = -0.06), suggesting a possible direct drug effect on skeletal muscle. Glucose requirement during the clamp at presentation was markedly lower in both treatment groups than in the non-diabetic subjects (gliclazide 2.1 +/- 0.3, diet 2.0 +/- 0.6 vs 7.8 +/- 0.4 mg kg-1 min-1, both p less than 0.001), and despite a marked improvement in both groups after treatment (4.3 +/- 0.4 and 3.1 +/- 0.5 mg kg-1 min-1, both p less than 0.001) remained lower than in the non-diabetic subjects (p less than 0.001).(ABSTRACT TRUNCATED AT 400 WORDS)

Blood Glucose↗
PubMed1991

Reactive hypoglycaemia in association with disordered islet function and abnormal hepatic glucose-6-phosphatase activity: response to diazoxide.

Severe reactive hypoglycaemia was confirmed in a non-diabetic male patient by a counter-regulatory hormone (GH, cortisol and catecholamine) response to profound hypoglycaemia induced by an intravenous glucose load. There was also evidence of disordered pancreatic islet cell paracrine regulation with hyperinsulinaemia and absent glucagon response to hypoglycaemia. A defect in the patient's hepatic glucose-6-phosphatase enzyme system was documented. Because of severe symptoms, dietary control was insufficient, but the patient responded clinically and biochemically to 18 months of oral diazoxide therapy. He also showed good biochemical response to a single dose (100 micrograms IM) of the somatostatin analogue octreotide.

Adult↗
PubMed1991

Mortality in Pacific island countries around 1980: geopolitical, socioeconomic, demographic and health service factors.

Inhabitants of Pacific island countries experience a wide range of levels and cause structures of mortality. Data on socioeconomic, geopolitical and demographic variables have been analysed here to identify correlates and determinants of mortality in Pacific island countries circa 1980. The mortality data used in the study were the best available for the period and are reasonably accurate; descriptive data were derived from recognised sources. Political status was a major correlate, with independence positively associated with mortality. However, the influence of political status was partly accounted for by economic and social variables. Economic indices, particularly imports per capita, were major inverse correlates of mortality. Disparities in life expectancy occurred between malarious and nonmalarious countries, and these were not explicable by other factors. Melanesians, especially women, experienced high mortality rates. Education and doctor availability were both associated with increased life expectancy. Intercorrelation and confounding need to be taken into account in the interpretation of this analysis. The results have ramifications for policy development in the Pacific island countries themselves, and for investment and aid programs from major donor nations and organisations.

Cross-Sectional Studies↗
PubMed1991

Eyelid leishmaniasis in a patient with neurogenic ptosis.

A patient with chronic progressive external ophthalmoplegia contracted cutaneous leishmaniasis of the upper eyelid. Infection of this site is rare because eyelid movements usually prevent the sandfly vector from biting the skin there. It is postulated that the relative immobility of the upper eyelid in this patient was a major predisposing factor for the infection.

Antimony Sodium Gluconate↗
PubMed1991

Use of probes for ZFY, SRY, and the Y pseudoautosomal boundary in XX males, XX true hermaphrodites, and an XY female.

Three XX males, two XX true hermaphrodites, and an XY female were studied for possible deletions using probes for the recently characterised SRY gene and the pseudoautosomal boundary. The XX males and true hermaphrodites were negative for all three probes, while the XY female was positive. One XX male and one XX true hermaphrodite were sibs. A previous sib pair of an XX male and an XX true hermaphrodite have been shown to be positive for Y chromosomal material near the pseudoautosomal boundary. Thus, both phenotypes can be produced from different mutations, some involving the SRY gene and others not.

Adolescent↗
PubMed1991

The influence of health insurance status on the organisation of patient care in Sydney public hospitals.

Utilising intensive semi-structured interviews with health professionals working in public hospitals in Sydney, a comparison was made of the perceived similarities and differences in the medical and administrative management of patients who were covered by Medicare and those who were privately insured. Interviewees argued that there was evidence of preferential access to public hospital care for privately insured patients due to medical misrepresentation of the urgency of their cases. They reported that some medical and administrative practices existed which compromised the choice of admission as a Medicare patient for those with private insurance, and for those without private insurance who were referred to hospital by a specialist. It was suggested also by the interviewees that medical considerations encouraged continuity of specialist care for Medicare patients admitted to hospital when they were known to an attending specialist. Such an allegation places in some doubt the claim made by private insurers that choice of doctor is permitted only under their cover. Interviewees did not report knowledge of any form of compromise in the quality of hospital care on the basis of medical preference for private patients. However, it was reported that private patients may, in some instances, be denied a full range of hospital services due to doctors' attempts to monopolise their treatment.

Continuity of Patient Care↗
PubMed1991

The lyso-precursor of platelet-activating factor (lyso-PAF) in ischaemic myocardium.

While it has been postulated that lyso-PAF and PAF might contribute to structural and functional damage in myocardial ischaemia, there has been no clear evidence for the accumulation of these bioactive compounds in ischaemic myocardium. In open chest, anaesthetised dogs, the proximal left anterior descending coronary artery was ligated and myocardial samples from the central ischaemic and normal areas assayed for lyso-PAF, free arachidonic acid and PLA2 activity. Ischaemic myocardium contained 50 +/- 29% (SD) more lyso-PAF than non-ischaemic myocardium after 20 min ischemia (P less than 0.002; N = 8) and 53 +/- 39% more after 60 min (P less than 0.01; N = 8) but there was no difference after 10 min (N = 8). Free arachidonic acid significantly increased in ischaemic myocardium after 60 min (122 +/- 136%; P less than 0.05) while no increase in PLA2 activity was found in-vitro. Since lyso-phospholipids themselves damage cell membranes and, additionally, lyso-PAF is the precursor of PAF which has potent effects on platelets, leukocytes and small vessels, the increase in lyso-PAF in ischaemic myocardium could contribute to myocardial damage.

Acetylation↗
PubMed1991

Separation of two subpopulations of old human fibroblasts by mitochondria (rhodamine 123) fluorescence.

The mitochondria-binding fluorescent dye rhodamine 123 (R123) was used to sort two subpopulations of cells from mass cultures of old human fibroblasts (HF). Both subpopulations showed unusual dye retention kinetics when compared to young HF. Additionally, electron microscopy revealed differences in numerical density of mitochondria between young and old HF. Moreover, the two subpopulations exhibited differences in radiolabeled thymidine incorporation and proliferative capacity. The results obtained suggest a possible relationship between mitochondria, proliferative potential and cellular aging.

Cell Division↗
PubMed1991

A seroepidemiological study of hepatitis B amongst Fiji health care workers.

Hepatitis B immunization for health care workers is common policy in many countries where they constitute a particular at risk group. A seroepidemiological study of hepatitis B virus (HBV) in Fiji health care workers was conducted to determine whether this occupational group (or subgroups thereof) were at higher risk of infection than the general Fiji population. The purpose of this study was to ascertain whether health staff should be immunized, or whether it would be more productive to focus resources on neonatal immunization. Blood samples were obtained from 2,639 health workers and the sera analysed by radio-immunoassay for hepatitis B surface antigen (HBsAg), and hepatitis B surface antibody (anti-HBs). Prevalence rates of HBV markers of infection were compared with those observed in the general population, from a previous population-based cluster sample survey. Approximately 70% of the health care staff participated in the study. Prevalence of total HBV markers was 24%. The rate of HBsAg was 5%. Sex and ethnic group specific prevalence rates varied. Male subjects, Fijians and "other" Pacific Islanders all experienced higher rates of infection. Rural/urban and age related trends were also observed. Rates of infection in health staff were lower than those reported in the general population. Previous studies have indicated that most of the transmission of hepatitis B in hyperemdemic Pacific populations occurs at birth or within the next few years. There was no consistent pattern of hepatitis B infection in different occupational groups of health care workers. Certain relatively socially homogeneous subgroups of health workers were analysed separately, and among these health workers there was evidence for increased risk of infection due to exposure to blood or used hypodermic syringes, but not due to patient contact. Until health staff assume a higher risk of infection than the general Fijian population, efforts directed at community-wide control of hepatitis B continue to be the most appropriate use of resources.

Adolescent↗
PubMed1990

Comparison of non-mydriatic retinal photography with ophthalmoscopy in 2159 patients: mobile retinal camera study.

OBJECTIVE: To determine whether non-mydriatic Polaroid retinal photography was comparable to ophthalmoscopy with mydriasis in routine clinic screening for early, treatable diabetic retinopathy. DESIGN: Prospective study of ophthalmoscopic findings according to retinal camera screening and ophthalmoscopy and outcome of referral to ophthalmologist. SETTING: Outpatient diabetic clinics of three teaching hospitals and three district general hospitals. PATIENTS: 2159 Adults selected randomly from the diabetic clinics, excluding only those registered as blind or those in wheelchairs and unable to enter the screening vehicle. MAIN OUTCOME MEASURES: Numbers of patients and eyes correctly identified by each technique as requiring referral with potentially treatable retinopathy (new vessel formation and maculopathy) and congruence in numbers of microaneurysms, haemorrhages, and exudates reported. RESULTS: Camera screening missed two cases of new vessel formation and did not identify a further 12 but indicated a need for referral. Ophthalmoscopy missed five cases of new vessel formation and indicated a need for referral in another four for other reasons. Maculopathy was reported in 147 eyes with camera screening alone and 95 eyes by ophthalmoscopy only (chi 2 = 11.2; p less than 0.001), in 66 and 29 of which respectively maculopathy was subsequently confirmed. Overall, 38 eyes received laser treatment for maculopathy after detection by camera screening compared with 17 after ophthalmoscopic detection (chi 2 = 8.0; p less than 0.01). Camera screening underestimated numbers of microaneurysms (chi 2 = 12.9; p less than 0.001) and haemorrhages (chi 2 = 7.4; p less than 0.01) and ophthalmoscopy underestimated hard exudates (chi 2 = 48.2; p less than 0.001). CONCLUSIONS: Non-mydriatic Polaroid retinal photography is at least as good as ophthalmoscopy with mydriasis in routine diabetic clinics in identifying new vessel formation and absence of retinopathy and is significantly better in detecting exudative maculopathy.

Adolescent↗
PubMed1990

Metastasizing thymoma and myasthenia gravis. Favorable response to glucocorticoids after failed chemotherapy and radiation therapy.

Myasthenia gravis (MG) occurs in up to 44% of patients with thymoma. Thirty-three percent of these neoplasms are invasive but extrathoracic disease is rare. Recently, we saw a patient with MG and recurrent, metastasizing mixed lymphoepithelial thymoma, whose disease was resistant to combination chemotherapy and radiotherapy but who responded dramatically to treatment with daily glucocorticoids. Thus, therapy with daily glucocorticoids should be considered in the treatment of invasive or metastatic thymoma associated with MG, including when conventional surgery, radiotherapy, and chemotherapy have failed.

Drug Administration Schedule↗
PubMed1990

Increase in glomerular filtration rate in patients with insulin-dependent diabetes and elevated erythrocyte sodium-lithium countertransport.

Increased sodium-lithium countertransport in erythrocytes is found in patients with insulin-dependent diabetes mellitus (IDDM) and nephropathy. To determine whether such an increase precedes the onset of nephropathy and, if so, whether it is associated with changes in renal function, we measured erythrocyte sodium-lithium countertransport in 52 patients with IDDM but not nephropathy or hypertension and in 32 control subjects. Seventeen of the 52 patients with IDDM (33 percent) had sodium-lithium countertransport activity that exceeded the maximal activity in the control subjects (0.39 mmol of lithium per hour per liter of cells). Eighteen of the 52 patients with IDDM were studied in more detail. The 7 patients with raised sodium-lithium countertransport values had glomerular filtration rates (median, 159 ml per minute per 1.73 m2 of body-surface area; range, 134 to 197) that were significantly higher (P less than 0.01) than those in the remaining 11 patients with IDDM and normal sodium-lithium countertransport (median, 126 ml per minute per 1.73 m2; range, 110 to 176) or in the 10 control subjects (median, 128 ml per minute per 1.73 m2; range, 93 to 151). In the seven patients with elevated sodium-lithium countertransport, the filtration fraction (median, 0.27; range, 0.22 to 0.37) was also greater (P less than 0.01) than that in control subjects (median, 0.22; range, 0.18 to 0.28). There were no differences in renal function between the patients with IDDM and normal sodium-lithium countertransport and the control subjects. We conclude that sodium-lithium countertransport is increased in patients with IDDM before the onset of nephropathy and is associated with hyperfiltration. Thus, elevated sodium-lithium countertransport activity may be an early marker of diabetic nephropathy.

Adult↗
PubMed1990

Power to prevent.

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Acquired Immunodeficiency Syndrome↗