Functional expression cloning reveals proapoptotic role for protein phosphatase 4

Functional expression cloning strategies are highly suitable for the analysis of the molecular control of apoptosis. This approach has two critical advantages. Firstly, it eliminates prior assumptions about the properties of the proteins involved, and, secondly, it selectively targets proteins that are causally involved in apoptosis control and which affect the crucial cellular decision between survival and death. The application of this strategy to the isolation of cDNAs conferring resistance to dexamethasone and gamma-irradiation resulted in the isolation of a partial cDNA for the catalytic subunit of protein phosphatase 4 (PP4). Cells transfected with this partial cDNA in an expression vector downregulated PP4 and were resistant to both dexamethasone and UV radiation, as demonstrated by both membrane integrity and colony-forming assays. These observations suggest that PP4 plays an important proapoptotic role in T lymphocytes.

Long-term use of depot-norethisterone enanthate: effect on blood lipid fractions

This is the third report of a metabolic study on 56 long-term users (24 for 2-5 yr; 32 for over 5 yr) of the injectable contraceptive norethisterone enanthate (Net-En) and deals with the effects on the blood levels of lipoprotein fractions. There was no significant difference between this group and a group of 30 non-users in serum concentrations of triglycerides, total cholesterol, low density and very low density lipoproteins. There was a significant reduction in mean high density lipoprotein levels between the controls and the user groups (16% for the intermediate duration and 12% for the longer duration). Age, ethnic group, body-mass index and a close family history of cardiovascular disease were taken into account, as were various lifestyle factors: diet, exercise, alcohol consumption and smoking. In a smaller group, levels of apoproteins A and B were also assayed. There was a significant reduction in apoprotein A between controls and all users, but the significance was lost on adjusting for confounding variables. Consideration was given to the ratio of total cholesterol to high density lipoprotein cholesterol as an index of coronary risk. There were no significant differences in the total cholesterol:HDL-C ratio between controls and user groups. There was a significant interaction with ethnic group (Caucasian or Afro-Caribbean) in the response to duration of use.

High prevalence of hypertriglyceridaemia and apolipoprotein abnormalities in coronary artery disease

Serum lipids and apolipoproteins A-I and B were measured in 174 men aged less than 60 with angiographically confirmed coronary artery disease and in 572 healthy control men. Two thirds of the patients had raised age-corrected values of fasting serum cholesterol and/or triglyceride and/or a low high density lipoprotein (HDL) cholesterol compared with the controls. Eighteen (30%) of the 61 normolipidaemic patients had a concentration of serum apolipoprotein A-I below the 5th percentile of 233 controls. In normolipidaemic patients on beta blockers the relative prevalence of serum low density lipoprotein (LDL)-apolipoprotein B values above the 95th percentile of 339 controls was significantly increased. Discriminant function analysis showed that a raised concentration of serum triglyceride was the best discriminant between patients and controls, with raised LDL-apolipoprotein B and reduced apolipoprotein A-I coming second only to triglyceride in analyses where each was separately compared with all the lipid variables. These associations were highly significant and were independent of other influences, including beta blockade. These findings re-emphasise the importance of hypertriglyceridaemia as a risk factor and confirm that apolipoprotein abnormalities occur frequently in coronary disease, even in normolipidaemic patients.

Metabolic investigations with Femodene--an oral contraceptive containing gestodene and ethinyloestradiol

The metabolic effects of a new oral contraceptive Femodene (SHD 356C) containing 75 micrograms gestodene (delta-15-levonorgestrel) and 30 micrograms ethinyloestradiol were studied in two groups of women. Group 1 consisted of women not currently using oral contraceptives; Group 2 consisted of women switching to Femodene from their current oral contraceptive. Changes in lipid metabolism were assessed by measuring serum levels of cholesterol, triglycerides, LDL-C, VLDL-C, HDL-C, HDL2-C and HDL3-C. Minimal changes occurred in lipid metabolism apart from increases in triglyceride concentrations. Women in Group 1 showed a 105% increase in SHBG levels and a 51% increase in caeruloplasmin levels compared to increases of 33% and 2% in women in Group 2. A comparison of the two groups of women suggested that the gestagen in Femodene exerted a less anti-oestrogenic effect than most of the gestagens currently used in oral contraceptives. No significant changes occurred in liver function (assessed by estimation of gamma-glutamyl transferase) or in the coagulation factors, Factor X and antithrombin III. Minor effects on glucose tolerance as assessed by blood glucose and plasma insulin levels were noted. These minimal effects on metabolism, combined with its high efficacy and acceptability shown in clinical trials, makes Femodene an ideal alternative to currently used oral contraceptives.

Efficacy of mevinolin as adjuvant therapy for refractory familial hypercholesterolaemia

Mevinolin, a potent inhibitor of cholesterol synthesis, was used as a therapeutic adjuvant in patients with refractory familial hypercholesterolaemia for an average period of 13 months. Sustained decreases in serum cholesterol of 23 and 31 per cent were achieved by doses of 20 mg and 40 mg/day respectively in 13 heterozygotes already on cholestyramine or after partial ileal bypass. Administration of 80 mg/day to three patients undergoing plasma exchange reduced peak serum cholesterol levels by 11.5 per cent in two homozygotes and by 17 per cent in a double heterozygote for familial hypercholesterolaemia and type III hyperlipoproteinaemia. The decrease in cholesterol was largely confined to low-density lipoprotein and no significant changes occurred in serum triglyceride or high-density lipoprotein cholesterol. Mevinolin was well-tolerated except in one patient who developed myositic symptoms; asymptomatic, transient elevations of serum enzymes were observed in five others. Short and long Synacthen tests showed no evidence that the drug impaired adrenocortical response to ACTH. These results indicate that mevinolin provides a safe and highly effective means of reducing LDL levels in patients with heterozygous familial hypercholesterolaemia refractory to conventional treatment but is less useful in homozygotes.

Coronary artery disease and haemostatic variables in heterozygous familial hypercholesterolaemia

Haemostatic variables were measured in 61 patients with heterozygous familial hypercholesterolaemia, 32 of whom had evidence of coronary heart disease. Age adjusted mean concentrations of plasma fibrinogen and factor VIII were significantly higher in these patients than in the 29 patients without coronary heart disease, but there were no significant differences in serum lipid concentrations between the two groups. Comparisons in 30 patients taking and not taking lipid lowering drugs showed lower values for low density lipoprotein cholesterol, high density lipoprotein cholesterol and antithrombin III, and a higher high density lipoprotein ratio while receiving treatment. The results suggest that hypercoagulability may play a role in the pathogenesis of coronary heart disease in patients with familial hypercholesterolaemia.

The effect of continuous subcutaneous insulin infusion on serum lipids

The effect of continuous subcutaneous insulin infusion (CSII) on serum lipids was examined in 2 groups of insulin dependent diabetic patients. Twelve paired patients selected by a random procedure to be treated with CSII or conventional insulin injections had lipids measured monthly for 6 months. A more heterogenous group of 13 CSII treated patients including the 6 randomised patients had lipids measured initially and after their maximum duration of CSII (range 3 to 18 months). Significant falls were seen in HbAI, plasma glucose and triglycerides in CSII treated patients whether the 6 randomised or the group of 13 were examined. High density, lipoprotein cholesterol (HDL-C) rose significantly in both groups. In the larger group of 13, a drop in the low density lipoprotein cholesterol (LDL-C) to HDL-C ratio and LDL-C was also seen. Control patients showed no significant changes. These findings confirm but are slightly different from improvements in lipids found in other studies of long-term CSII. In addition it was demonstrated that these changes could be maintained in patients managed outside the strict rigors of a controlled study.

Effect of a new contraceptive ring releasing 20 micrograms levonorgestrel daily on blood lipid levels and glucose tolerance

Fifteen healthy subjects used a contraceptive device, namely an intravaginal ring releasing 20 micrograms levonorgestrel daily, for 12 weeks. High, low and very low density fractions of cholesterol, triglyceride and phospholipids were measured, together with oral glucose tolerance before and after 12 weeks of use. There were no significant differences in any of the plasma lipid fractions or in glucose tolerance.

Multiple endocrine neoplasia type II: the role of gastrointestinal humoral factors in calcitonin release following alcohol and pentagastrin stimulation

Familial medullary carcinoma of thyroid (MCT) can be diagnosed early by measuring stimulated plasma calcitonin following provocation with 50 ml of oral whisky, or 0.5 microgram kg-1 i.v. pentagastrin. The calcitonin release, however, can be variable following both stimuli. To determine whether a humoral mechanism might be involved in mediating this calcitonin release, nine gut peptides, histamine, alcohol, calcium, and calcitonin, were measured in the plasma of eight patients whose family was affected by multiple endocrine neoplasia Type II syndrome. Pentagastrin produced significant rises in plasma calcitonin, histamine and pancreatic polypeptide. Whisky produced a variable rise in plasma alcohol, but significant rises in plasma calcitonin, histamine and pancreatic polypeptide as well as insulin (P less than 0.05). This study suggests that histamine may be the mediator of calcitonin release following provocation by either pentagastrin or alcohol. Histamine infusion requires evaluation as a screening test for MCT in MEN II syndrome.

Effects of short term beta adrenoreceptor blockade on serum lipids and lipoproteins in patients with hypertension or coronary artery disease

The effects of beta adrenoceptor blockade with propranolol or pindolol on serum total cholesterol, low density lipoprotein cholesterol (LDL), high density lipoprotein cholesterol (HDL), and its subfractions HDL2 and HDL3, serum triglyceride, and Intralipid clearance were studied in 17 normolipidaemic, non-diabetic patients with hypertension or angina pectoris. Both pindolol and propranolol had similar effects on fasting serum total and lipoprotein cholesterol concentrations. HDL2 cholesterol concentrations were reduced by 9 +/- 29% and HDL3 cholesterol increased by 11 +/- 16%, but there were no significant changes in total or LDL cholesterol in the combined groups after six weeks' treatment. After 12 weeks' treatment total cholesterol concentrations were reduced by 7 +/- 10% mainly owing to a reduction in the LDL fraction of 9 +/- 15%. Concentrations of HDL2 remained low, 8% less than control values. Serum triglyceride concentrations were increased by both drugs at six weeks but had returned to base values in the pindolol group by the twelfth week. Pindolol, but not propranolol, enhanced the rate of clearance of intravenous Intralipid.

Collagen content of atherosclerotic arteries is higher in smokers than in non-smokers

The biochemical composition of coronary endarterectomy and aortic samples obtained during 52 coronary artery bypass graft operations was analysed. The content of cholesterol or collagen relative to protein in the aorta or endarterectomy specimens did not correlate with serum total cholesterol, triglyceride, or high-density-lipoprotein cholesterol, nor were there any significant differences between samples from normotensive and hypertensive patients. However, smokers had a significantly higher content of collagen in coronary endarterectomy specimens and the aorta and a higher content of cholesterol in the aorta than non-smokers.

Effect of injectable norethisterone oenanthate (Norigest) on blood lipid levels

Lipid concentrations were measured in 74 blood samples from 61 women who had been using the injectable contraceptive Norigest (norethisterone oenanthate) for between 2 to 4-1/2 years. There were no significant changes in the concentrations of total cholesterol, total triglycerides and low density and very low density lipoprotein cholesterol but high density lipoprotein cholesterol was significantly reduced. The reduction in serum HDL-C levels was not correlated with either the serum norethisterone concentrations or the length of use of Norigest nor was it affected by obesity or smoking.

Effect of lipoprotein concentration and lecithin: cholesterol acyltransferase activity on cholesterol esterification in human plasma after plasma exchange

The rate of cholesterol esterification in plasma, plasma lecithin cholesterol acyltransferase (LCAT) activity and plasma lipoprotein levels have been measured in five subjects who underwent therapeutic plasma exchange to reduce their plasma cholesterol concentration. In the week following the exchange the cholesterol esterification rate and the plasma triglyceride concentration returned rapidly in parallel to pre-exchange levels, while high density lipoprotein (HDL) cholesterol and LCAT activity returned to normal more slowly but also in parallel. The data suggest that the rate-limiting factor for cholesterol esterification in plasma is unlikely to be solely the enzyme levels, but is probably a combination of factors, including the enzyme level and either substrate availabiltiy or product removal. Plasma very low density lipoprotein (VLDL) may either provide substrates for the reaction or provide a means of removing one of the products from the site of reaction.