FEASIBILITY OF CONDUCTING CARDIOVASCULAR OUTCOME RESEARCH IN AUSTRALIAN GENERAL PRACTICE: RESULTS FROM THE ANBP2 PILOT STUDY

1. The present study aimed to determine the feasibility of conducting a 5 year cardiovascular outcome trial of the treatment of 6000 elderly hypertensive patients in Australian general practices. 2. General practitioners (GPs) were invited to participate by mail and personal follow-up. Patient records were reviewed to identify subjects for a blood pressure (BP) screening programme. Blood pressure was measured on three occasions and eligible subjects were included if the average BP was 160 mmHg systolic or 90 mmHg diastolic if systolic BP was 140 mmHg. 3. Seven hundred and forty-one GPs were approached and 89 were enrolled in the study (12% of mail invites and 75% of those receiving a personal contact). In 16 practices where screening was completed, 82 000 records were reviewed to identify 4% patients eligible for screening. Twenty-two per cent of eligible subjects attended screening. Of 1938 subjects screened, 180 (9%) had BP 5=160/90 mmHg. Forty-seven percent of subjects (n = 916) were receiving antihypertensive therapy and 184 (20%) were withdrawn from therapy. One hundred and sixteen (63%) of these subjects had BP return to study entry levels within 6 weeks. Fifty-seven newly diagnosed and 81 previously treated subjects were randomized (7% of the screened population). 4. Based on the high participation rate of GPs, the response rate of patients to attend a BP screening programme and the 7% randomization to screening ratio for entry into the study, the ANBP2 pilot study has demonstrated that it is feasible to recruit subjects from Australian general practices to a cardiovascular outcome trial.     

Neuropsychological functions,sleep, and mental health in adults with Klinefelter syndrome

A few studies have examined neuropsychological functions, sleep, and mental health combined in Klinefelter syndrome (KS; 47,XXY). We investigated neuropsychological functions with standard tests, sleep with actigraphy, and self‐reported mental health in 30 men with KS (Mean age = 36.7 years) compared to 21 controls (Mean age = 36.8 years). Men with KS scored significantly lower on mental speed, attention span, working memory, inhibition, and set‐shifting tests, as well as overall IQ (mean effect size difference Cohen's d = 0.79). Men with KS had significantly longer night wakes, with no differences in other sleep variables (mean d = 0.34). Men with KS reported poorer mental health than controls (mean d = 1.16). Regression analyses showed neuropsychological functions explained variance in some sleep domains for men with KS but not for controls. Neuropsychological functions explained variance in some mental health domains for controls. For men with KS, however, verbal IQ was the only significant predictor of mental health. Altogether, men with KS display problems in neuropsychological functions and mental health but do not appear different from controls on most sleep parameters. Our findings indicate that relations between neuropsychological functions, sleep, and mental health differ between men with KS and controls.     

Apoptosis and expression of Bax, Bcl-x, and Bcl-2 apoptotic regulatory proteins in colorectal carcinomas, and association with p53 genotype/phenotype.

AIMS: Spontaneous apoptosis and expression of the apoptotic regulatory proteins Bax, Bcl-x, and Bcl-2 were investigated in 50 colorectal carcinomas. The p53 genotypes/phenotypes and BAX genotypes were also determined, and possible associations of these with apoptosis and/or with expression of the different apoptotic regulatory proteins were studied. METHODS: Terminal deoxynucleotidyl transferase (TdT) mediated dUTP labelling of DNA fragments was used to detect apoptotic tumour cells in sections and peroxidase immunohistochemistry was used to assess protein expression. p53 genotype/phenotype was determined using constant denaturant gel electrophoresis/immunoblotting and bax genotype was determined using polymerase chain reaction based methods. RESULTS: The distribution of tumour apoptotic indices was bimodal with a natural cut off at 1.0% (range, 0.0-5.4%); the median fraction of apoptotic tumour cells was 0.8%. Tumour apoptosis was not associated significantly with tumour DNA ploidy status. Normal mucosal tissue had less than 0.1% apoptotic cells. Staining intensities for Bax, Bcl-x, and Bcl-2 were strong; that is, equivalent to or greater than positive normal mucosal cells, in 11 of 50, 20 of 49, and 20 of 48 carcinomas. Frameshift mutations in the bax gene were detected in three of 42 tumours analysed, all of which were DNA diploid, and Bax protein expression in these tumours was absent or very low. Bax, Bcl-x, and Bcl-2 protein expression were not correlated with tumour apoptosis or tumour DNA ploidy status. p53 was expressed in 34 of 50 tumours and p53 gene mutations were detected in 22 of 29 p53 positive tumours analysed. Apoptosis was significantly lower in a greater number of p53 positive tumours than p53 negative tumours. In addition, Bcl-2 protein expression was significantly higher in a greater number of p53 positive tumours compared with p53 negative tumours. Bax and Bcl-x protein expression were not significantly associated with p53 phenotype/genotype. CONCLUSIONS: The results indicate that acquisition of a p53 phenotype is associated with lower spontaneous apoptosis and higher expression of Bcl-2. The results also suggest that p53 is not a major determinant for Bax expression in colorectal carcinomas in vivo.     

Loop diuretics reduce lithium reabsorption without affecting bicarbonate and phosphate reabsorption

The effects of the loop diuretics ethacrynic acid and bumetanide on lithium, bicarbonate and phosphate reabsorption were compared in 16 anaesthetized, normovolaemic dogs. In six dogs, ethacrynic acid (3 mg kg-1 body wt) significantly reduced absolute lithium reabsorption from 29.3 +/- 4.1 to 19.0 +/- 3.4 mumol min-1, fractional lithium reabsorption from 0.65 +/- 0.04 to 0.37 +/- 0.04 and fractional chloride reabsorption from 1.00 +/- 0.00 to 0.65 +/- 0.02. Bicarbonate and phosphate reabsorption did not decrease significantly. In six other dogs, bumetanide (30 micrograms kg-1 body wt) gave similar results. Absolute lithium reabsorption significantly decreased from 34.0 +/- 2.2 to 18.1 +/- 2.6 mumol min-1 and fractional lithium reabsorption decreased from 0.50 +/- 0.03 to 0.25 +/- 0.03. Fractional chloride reabsorption decreased from 0.98 +/- 0.00 to 0.61 +/- 0.05, whereas bicarbonate and phosphate reabsorption were not significantly altered. Thus, both loop diuretics greatly reduced lithium reabsorption. We propose that loop diuretics inhibit passive lithium reabsorption in the thick ascending limb of Henle's loop by reducing the lumen-positive electrical potential that drives passive cation transport.     

Low oxygen cost of carbonic anhydrase-dependent sodium reabsorption in the dog kidney

To examine the oxygen requirement of carbonic anhydrase-dependent sodium reabsorption in the proximal tubule, 18 anaesthetized dogs were studied under conditions of saturated distal NaCl reabsorption; the latter was accomplished by volume expansion (all groups) combined with infusion of loop diuretics (groups 1 and 3). Acetazolamide reduced HCO3- reabsorption by 602 +/- 32 mumol min-1 (55%, group 1) and by 777 +/- 103 mumol min-1 (66%, group 2). This was accompanied with a reduction in sodium reabsorption and oxygen consumption in a molar delta Na/delta O2 ratio of about 45 in both groups of dogs. The delta HCO3/delta O2 ratio averaged 16 +/- 1, which was not significantly different from the theoretical value of 18 expected for transcellular sodium transport by Na+, K+-ATPase. Mannitol (group 3) reduced NaCl reabsorption by 37 +/- 2% without affecting NaHCO3 reabsorption or oxygen consumption significantly. We conclude that carbonic anhydrase-dependent NaCl reabsorption in the proximal tubules is passive, and that NaHCO3 reabsorption is the only important active sodium transport which is sensitive to inhibition of carbonic anhydrase.     

P53 expression is associated with a high-degree of tumor DNA aneuploidy and incidence of p53 gene mutation, and is localized to the aneuploid component in colorectal carcinomas

p53 protein expression was studied by immunoblotting in 34 colorectal carcinomas and 28 of the corresponding normal mucosas, and correlated with tumor DNA ploidy as measured by flow cytometry. p53 protein was detected in 35% (12/34) of the tumors; the normal mucosas were negative. Fifty-five percent (12/22) of the tumors examined for mutations within the four hotspots (exons 5-8) of the p53 gene had point mutations. p53 expression correlated significantly with the presence of p53 gene mutations; 67% (8/12) of the tumors with mutations expressed p53, whereas only one of 10 tumors where no mutations were detected expressed the protein (p=0.01). Four tumors with p53 gene mutations did not express p53. Fifty-nine percent (20/34) of the tumors were aneuploid. p53 expression correlated significantly with aneuploidy; a total of 55% (11/20) of the aneuploid tumors were positive for p53 compared to 7% (1/14) of the diploid tumors (p=0.009). All of the 11 highly aneuploid tumors (1.31 less-than-or-equal-to DNA index (DI); less-than-or-equal-to 1.86) expressed p53, whereas all of the 9 moderately aneuploid tumors (1.11 less-than-or-equal-to DI less-than-or-equal-to 1.29) were p53-negative. Flow cytometry was also used to resolve cell cycle- and ploidy specific p53 expression in nuclei in 4 aneuploid tumors. p53 expression in these tumors was confined to the aneuploid component, whereas the diploid component was negative. p53 was seen in nuclei in all phases of the cell cycle of proliferating aneuploid cells. Neither p53 expression nor tumor DNA ploidy were correlated with Dukes' stage (p=1.00 and 0.72, respectively). The data suggest that high levels of mutant p53 may play a causative role in the generation of highly aneuploid tumors.     

Metabolic profiles in closely controlled diabetic pregnancies during the third trimester

Summary In 5 closely controlled pregnant diabetics (duration of pregnancy 237–266 days) and 5 pregnant non-diabetics (duration of pregnancy 210–278 days) 4-hourly blood samples were taken throughout a 24 h period and analyzed for blood glucose, lactate, pyruvate, 3-hydroxybutyrate and acetoacetate, plasma non-esterified fatty acids (NEFA), glucagon and cortisol. 24 h urine specimen was analyzed for total catecholamines and 4-hydroxy-3-methoxymandelic acid. There were few significant differences in concentrations of metabolites and hormones in the two groups at any time, although the variations about the mean was usually greater in the diabetics. Thus for blood glucose in diabetics, mean value was 4.4 mmol/l, coefficient of variation 43%; in non-diabetics 4.1 mmol/l and 10% respectively. Mean plasma 3-hydroxybutyrate in diabetics was 0.47 mmol/l, coefficient of variation 55%; in non-diabetics 0.44 mmol/l and 37% respectively. Plasma non-esterified fatty acid levels were significantly higher in the diabetics (0.47 mmol/l) than in the non-diabetics (0.26 mmol/l). Coefficients of variation were 46% and 33% respectively. Two conclusions can be drawn; first, when near normal mean values for blood glucose are achieved, other metabolite and hormone levels are also near normal; second, even when the available means for diabetic control, strict diet and insulin-mixtures twice daily, are used at their maximum, metabolism in diabetics is more unstable than in non-diabetics.