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Biomedical subjects

C A Jackson

Publications and source records attributed to C A Jackson.

89 records · Page 5Linked to original sources
PubMed1981

Inhibition of prostacyclin and platelet thromboxane A2 after low-dose aspirin.

To compare the inhibitory effects of aspirin on prostaglandin synthesized by vessel walls and platelets, we obtained vein segments from five subjects before they were given 150 or 300 mg of aspirin and at various intervals afterward. We then measured prostacyclin (PGI2) synthesis with a radioimmunoassay for its stable metabolite, 6-keto-prostaglandin F1 alpha. Platelet production of thromboxane A2 was measured with a radioimmunoassay for its stable metabolite, thromboxane B2. Two hours after aspirin had been given, 81 to 100 per cent inhibition of PGI2 synthesis was demonstrated; 86 per cent inhibition was still evident in one subject tested eight hours after administration. Simultaneously, platelet production of thromboxane B2 was completely inhibited for more than 24 hours. We conclude that there is little difference between the initial inhibitory response of platelet cyclooxygenase and that of vessel-wall cyclooxygenase to these doses of aspirin. Our results also indicate that in male subjects the prolonged template bleeding time after aspirin is not the consequence of selective inhibition of platelet production of thromboxane.

Adult↗
PubMed1977

The occurrence of the intestinal fluke Sphaeridiotrema globulus in domestic ducks in New South Wales.

A mortality in muscovy ducklings caused by infection with the intestinal fluke, S. globulus, is described. The disease was characterised by depression, anorexia, wasting, diarrhoea and high mortality. The major pathological lesions were associated with the attachment sites of the flukes and consisted of severe enteritis with ulceration, principally affecting the jejunum, but also involving the duodenum and ileum. Experimental infections were produced in ducklings by oral administration of either G. austrialis infected with S. globulus metacercariae or S. globulus metacercariae or S. globulus metacercariae. The small, dextral, operculate snail G. australis was identified as the intermediate host and G. australis and an unidentified planorbid as transport hosts. L. tomentosa was also able to be a transport host. The epidemiology of the outbreak and aspects of acquired resistance are presented.

Animals↗
PubMed1976

Field trials with lyophilised herpesvirus of turkeys vaccine against Marek's disease in layer and broiler rearing flocks.

The safety and immunogenicity of commercial lyophilised herpesvirus of turkeys (HVT) vaccine against Marek's disease (MD) was evaluated in 19 field trials involving 76,848 vaccinated and 87,590 control chickens. In the first series of 11 trials involving one commercial vaccine at a dose of 536 plaque forming units (PFU) there was a significant reduction in the incidence of MD (P less than 0.001) and in total mortality (P less than 0.001) from 0 to 18 weeks due to vaccination and the overall protection was 85.2%. In the second series of eight trials involving another commercial vaccine at a dose range of 1360 to 1900 PFU there was a significant reduction in the incidence of MD (P less than 0.001) from 0 to 18 weeks of age due to vaccination. The overall protection was 77.8%. In both series there was a significant difference in MD mortality between meat breeders and crossbred pullets (P less than 0.005) in response to vaccination. There was also a significant difference in total mortality from 0-6 weeks of age between the two series suggesting either differences in response to the two vaccines or differences in the vaccination technique. In a number of trials the incidence of MD was low in the controls, however, where MD incidence was above 2% in the controls protection usually exceeded 80%. It was concluded the vaccines were safe and efficacious and the degree of protection was comparable to that obtained by HVT vaccines described in other countries.

Animals↗
PubMed1975

Comparison of two lidocaine preparations by in vivo assay methods.

An in vivo study was conducted to determine if there were differences in local anesthetic potency between two commercial brands of lidocaine. The two preparations were evaluated in terms of onset of action, peak effects and duration of action using a double-blink technique. Both products were tested at concentrations of 0.25%, 0.50% and 1%. Each were evaluated for conduction (in rats), topical (in rabbits) and in filtration (in guinea pigs) anesthesia. No clinically significant differences between the two commercial preparations were found.

Anesthesia, Conduction↗
PubMedDate not supplied

Treatment typically provided for comorbid anxiety disorders.

OBJECTIVE: To study whether the extent and type of treatment for comorbid anxiety disorders varies for patients with depression, hypertension, diabetes, and heart disease treated by general medical clinicians. METHODS: Data are from 2189 general medical patients with and without comorbid anxiety disorders in the Medical Outcomes Study. Treatment data were based on clinician reports of counseling provided during a visit and patient reports of recent medication use. RESULTS: Patients with comorbid anxiety disorders were more likely to receive treatments for anxiety disorders than those without anxiety disorders. Among those with anxiety disorders, the use of psychosocial counseling and psychotropic medication was greater for patients with depression than for patients without depression who had chronic medical conditions. Minor tranquilizers were used more commonly than antidepressants, regardless of the type of comorbid condition. Among patients with anxiety disorders, those visiting medical subspecialists were more likely to use minor tranquilizers than those visiting family practitioners or internists. Patients of family physicians with chronic medical conditions (but not with depression) were less likely than similar patients of internists to use minor tranquilizers whether or not anxiety disorders were present. CONCLUSIONS: Anxiety disorders co-occurring with another disease (medical illness or depression) increases the likelihood of counseling and the use of psychotropic medication in the general medical sector. Patients with a chronic medical illness with or without comorbid anxiety disorders visiting family physicians are less likely to use minor tranquilizers than those visiting subspecialists or internists.

Adult↗
PubMedDate not supplied

Glucose intolerance and hypertension in north London: the Islington Diabetes Survey.

In a general practice-based screening survey, 1040 (63.3%) of a randomly selected sample of 1644 people over the age of 40 years were examined for diabetes mellitus (DM) and hypertension (HT). Glucose intolerance was assessed by a single 2 h post-load blood glucose estimation and HT (diastolic blood pressure greater than or equal to 95mmHg by a single blood pressure reading) or being on anti-hypertensive treatment. The sample included 41 patients (2.1%) with known DM and 135 (12.5%) with known HT. Screening identified 27 (2.6%) new diabetics (16 women) and 43 subjects (4.1%) with impaired glucose tolerance (30 women). A further 30 known diabetics over the age of 40 and 12 diabetics under 40 were registered at the practice. The estimated prevalence of diabetes in the over 40s was 4.6% and in all ages was 1.6%. DM appeared to affect Afro-Caribbeans more commonly than Caucasians among those examined (5.9% versus 2.6%) though this difference did not reach statistical significance (z = 1.1106, p = 0.134). A total of 190 subjects (17.5%) were found to have HT, of whom 55 (5.1%) were newly diagnosed; 10.2% of the sample were on anti-hypertensive treatment, and in 79.3% of these the blood pressure was well controlled (diastolic less than 100 mmHg). HT was more common among known diabetics with a prevalence of 35.4%, of whom one-third were previously undiagnosed. HT affected Afro-Caribbeans significantly more commonly than Caucasians (z = 4.206, p less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMedDate not supplied

The glycohaemoglobin assay as a screening test for diabetes mellitus: the Islington Diabetes Survey.

Blood glucose 2 h after an oral glucose load (2hBG) and glycohaemoglobin (GHb) (Corning agar-gel electrophoresis) levels were used as screening tests in a general practice diabetic screening programme. The diagnosis of diabetes (DM) was based on a separate oral glucose tolerance test (OGTT) in 223 of 1040 screened subjects, selected as a stratified sample biased towards higher levels of 2hBG and GHb. The GHb assay was also repeated at the recall examination and urine was tested for glycosuria before and after glucose administration. At a cut-off level of 8.1%, the screening GHb assay correctly identified 90% of all probable diabetics with a specificity of 85.3% (95% Cl 83.3-87.3%) and a positive predictive value of 14.0% (9.0-19.0%). The specificity of the screening GHb assay as a screening test for true DM was 45.8% (39.0-52.4%) at 90% sensitivity, and that of the recall GHb assay was 64.5% (57.9-71.1%). The screening 2hBG was 93.3% (88.9-97.7%) specific at 90% sensitivity as a screening test for true DM diagnosed by OGTT at recall. The test characteristics for fasting glycosuria were: sensitivity 16.7% (0-37.8%) and specificity 98.0% (96.0-100.0%). Equivalent values for the post-glucose test for glycosuria were: 72.7% (46.4-99.0%) and 77.4% (70.1-84.7%), respectively. While GHb assay is a poorer screening test for DM than the 2hBG at the single cut-off level quoted, comparison of the accuracy of the two tests shows that the GHb assay is only marginally less accurate. It is superior to testing for glycosuria as a screening test for DM and can be performed on any random blood sample, facilitating its use in population screening.

Adult↗
PubMedDate not supplied

Glucose tolerance and glycohaemoglobin: a population study of male-to-female ratios.

We have studied blood glucose concentrations 2 h after a 75g glucose load, and glycohaemoglobin as assayed by agar gel electrophoresis, in 1084 subjects over the age of 40 in a community screening survey. There were 16 newly diagnosed diabetic women (2.7%) and 11 men (2.5%). The mean level of 2h blood glucose was 5.6 +/- 2.04 mmol/l in women and 5.33 +/- 2.14 mmol/l in men (p less than 0.002) but when corrected for age and weight the mean levels were 5.55 mmol/l in women and 5.40 mmol/l in men (p greater than 0.2). Mean levels of glycohaemoglobin were 7.30 +/- 1.10% in women and 7.17 +/- 1.18% in men (p less than 0.02) but when adjusted for blood glucose and age these were 7.25% in both sexes (p greater than 0.9). Differences in glucose tolerance in this population are related to differences in age and weight. There is no evidence for differences in glycosylation in men and women.

Adult↗
PubMedDate not supplied

Changes in injection-site blood flow and plasma free insulin concentrations in response to stress in type 1 diabetic patients.

In order to test the effect of stress on injection-site blood flow and blood glucose control, 16 C-peptide negative patients were studied on a stress day, when a 30-min Stroop Colour-Word Test was completed, and a control day, when a cartoon was shown. Unmodified insulin was injected subcutaneously into the thigh before the test, and injection-site blood flow measured throughout the experiment with a thermal clearance probe. Blood glucose and plasma free insulin, glucagon, growth hormone, cortisol, and catecholamines were measured at intervals before, during, and after stress. Patients showed a significant overall rise in injection-site blood flow with the Stroop test from 4.1 (SD 1.6) to 5.2 (1.8) ml 100-g-1 min-1 (increase 38.1 (37.8) %, p less than 0.001). There was no overall significant difference between stress and control days in blood glucose or plasma free insulin levels, with differences in mean blood glucose levels during stress between the 2 days varying from -4.2 mmol l-1 to +6.3 mmol l-1 in individual patients. The increase in injection-site blood flow with stress correlated significantly with the increase in plasma free insulin concentration both during (r = 0.55) and after stress (r = 0.71). Differences in blood glucose concentration between stress and control day for each patient showed strong correlation with differences in plasma free insulin both during (r = -0.73) and after stress (r = -0.79). Differences in counter-regulatory hormones occurred but correlated poorly with blood glucose difference. Thus, stress affects the blood flow at the injection site, and this in turn affects insulin absorption. Most of the blood glucose response to stress is explained by changes in free insulin concentration.

Adult↗