Irbesartan has no short‐term effect on insulin resistance in hypertensive patients with additional cardiometabolic risk factors (i‐RESPOND)

Aims: Intervention studies have shown that angiotensin receptor blockers (ARB) may reduce the incidence of type 2 diabetes mellitus. It is currently unclear whether short‐term therapy with ARBs affects metabolic parameters. Methods: i‐RESPOND, a randomised, controlled, multicentre, double‐blind study evaluated the effect of 16 weeks of irbesartan vs. hydrochlorothiazide (HCTZ) on insulin resistance as well as on lipid and inflammatory parameters in hypertensive subjects with metabolic syndrome. Patients received irbesartan (150 mg/d; n = 211) or HCTZ (12.5 mg/d; n = 215), titrated to 300 mg/day and 25 mg/day respectively. In a second part of the study (weeks 16–28), patients initially randomised to irbesartan received additional HCTZ and vice versa. Results: At week 16 both irbesartan and HCTZ had no effect on insulin resistance measured by the Matzuda index and beta‐cell function. Similarly, in the second part of the study (week 16–28) no differences between irbesartan and HCTZ with respect to glucose metabolism were observed. However, irbesartan induced beneficial changes in high‐sensitivity‐C‐reactive protein (hs‐CRP) (irbesartan: ?5.5 ± 5.2%; HCTZ + 19.9 ± 6.5%, p = 0.0024) and in urinary albumin/creatinine ratio (ACR) (irbesartan: ?13%; HCTZ + 9%; p = 0.0041) compared with HCTZ despite a similar decrease in blood pressure in both treatment groups. Irbesartan and HCTZ were well tolerated and adverse events were comparable. Conclusion: Irbesartan did not show significant favourable effects on insulin resistance compared with HCTZ in this study; however, may have beneficial effects on inflammation and microalbuminuria in hypertensive patients with metabolic syndrome.     

Effects of selective beta 2-adrenoceptor blockade on serum potassium and exercise performance in normal men.

1. The differential effects of beta-adrenoceptor subtypes on potassium fluxes and exercise capacity were compared in eight healthy young men using single oral doses of the selective beta 2-adrenoceptor antagonist ICI-118551, the selective beta 1-adrenoceptor antagonist atenolol or the non-selective beta-adrenoceptor antagonist propranolol. The study was randomized, double-blind and placebo controlled. 2. Potassium in the venous effluent from the exercising muscles increased progressively with increasing exercise intensity. This response was augmented by propranolol, whereas neither atenolol nor ICI-118551 modified the response. After exercise potassium concentration fell exponentially with no difference between the treatment regimens. 3. Cumulative work was significantly reduced by ICI-118551 (6.4%, P = 0.04) and by propranolol (12.4%, P less than 0.01), whereas the reduction with atenolol (5.6%) did not reach statistical significance. 4. Atenolol and propranolol reduced peak heart rate by 23% and 29%, and peak systolic blood pressure by 9% and 11% respectively during maximal exercise. ICI-118551 caused a non-significant reduction in heart rate during submaximal exercise, with a significant reduction at maximum exercise (6% reduction), whereas systolic blood pressure was not different from placebo. Diastolic blood pressures were similar across all treatment regimens. 5. Similar glucose concentrations were obtained at baseline and at exhaustion during all treatment regimens. Lactate concentrations were comparable for any given exercise intensity irrespective of treatment regimens. Propranolol reduced lactate concentrations from the exercising muscles at maximum exercise in proportion to the reduction of maximal exercise capacity. 6. The subjective perception of fatigue was not affected by either beta 1- or beta 2-adrenoceptor blockade.(ABSTRACT TRUNCATED AT 250 WORDS)     

T-independent and T-dependent steps in the murine B cell response to antiimmunoglobulin

Sepharose-anti-Ig and purified populations of small, high-density B cells have been used to study the formation and function of B lymphoblasts. Sepharose-anti-Ig converts small, Ia-poor B cells with a high-buoyant density to large, Ia-rich, B blasts with a low-buoyant density. We find that this response proceeds efficiently in the absence of IL-4 (BSF-1) as well as most T cells, macrophages, and dendritic cells. Further development of the blasts requires an additional stimulus, such as LPS or the conditioned medium of stimulated EL-4 thymoma cells. Within 6 h, blasts begin to enter S phase and within 24 h most divide. At later times (48-72 h) most of the blasts are actively secreting IgM. Recombinant IL-1, -2, -3, and -4 have little or no effect on the B blasts, and a neutralizing mAb to IL-4 does not block the response to EL-4 Sn. We conclude that Sepharose-anti-Ig induces B cell blastogenesis in a T-independent fashion and that these blasts represent a highly enriched population of cells that respond to distinct, T cell-derived lymphokines.     

Effect of induced hypotension on serum concentrations of atropine after intramuscular administration

The serum concentrations of atropine after a single intramuscular injection of 0.01 mg/kg were determined by radioimmunoassay in nine general surgical patients during and after a combination anaesthesia and compared with those of 13 neurosurgical patients operated on during induced hypotensive anaesthesia (sodium nitroprusside plus trimetaphan). Surprisingly, comparable serum levels were found in both patient groups. We conclude that this kind of induced hypotension cannot be used as a model of drug absorption in such clinical situations as cardiac failure, haemorrhage or anaphylactic drug reactions.     

Enhanced Predictive Power of Quantitative TWA during Routine Exercise Testing in the Finnish Cardiovascular Study

Introduction: We examined whether quantification of T-wave alternans (TWA) enhances this parameter's capacity to evaluate the risk for total and cardiovascular mortality and sudden cardiac death (SCD).
Methods and Results: The Finnish Cardiovascular Study (FINCAVAS) enrolled consecutive patients (n = 2,119; 1,342 men and 777 women) with a clinically indicated exercise test with bicycle ergometer. TWA (time domain-modified moving average method) was analyzed from precordial leads, and the results were grouped in increments of 10 μV. Hazard ratios (HR) for total and cardiovascular mortality and SCD were estimated for preexercise, routine exercise, and postexercise stages. Cox regression analysis was performed. During follow-up of 47.1 ± 12.9 months (mean ± standard deviation [SD]), 126 patients died: 62 were cardiovascular deaths, and 33 of these deaths were sudden. During preexercise, TWA ≥ 20 μV predicted the risk for total and cardiovascular mortality (maximum HR >4.4 at 60 μV, P < 0.02 for both). During exercise, HRs of total and cardiovascular mortality were significant when TWA measured ≥50 μV, with 90 μV TWA yielding maximum HRs for total and cardiovascular death of 3.1 (P = 0.03) and 6.4 (P = 0.002), respectively. During postexercise, TWA ≥60 μV indicated risk for total and cardiovascular mortality, with maximum HR of 3.4 at 70 μV (P = 0.01) for cardiovascular mortality. SCD was strongly predicted by TWA levels ≥60 μV during exercise, with maximum HR of 4.6 at 60 μV (P = 0.002), but was not predicted during pre- or postexercise.
Conclusion: Quantification of TWA enhances its capacity for determination of the risk for total and cardiovascular mortality and SCD in low-risk populations. Its prognostic power is superior during exercise compared to preexercise or postexercise.     

Fibronectin in synovial fluid and tissue in rheumatoid arthritis

Fibronectin is a glycoprotein found in body fluids, loose connective tissue matrix and in basement membranes. Fibronectin in rheumatoid arthritis synovial fluid was immunologically indistinguishable from the plasma form, as shown by double-diffusion analysis. Fibronectin isolated from rheumatoid synovial fluid by affinity chromatography on gelatin--Sepharose had a polypeptide pattern similar to that of plasma fibronectin in SDS--polyacrylamide gel electrophoresis. In fifty-one patients with rheumatoid arthritis and related diseases fibronectin concentrations is synovial fluid were 445 +/- 103 micrograms/ml (mean +/- SD) and within normal range, 335 +/- 52 micrograms/ml, in plasma. Immunofluorescence staining showed a prominent increase of fibronectin in the proliferating synovial connective tissue in rheumatoid arthritis as compared to normal synovial membrane. The results suggest an increased local production of fibronectin in rheumatoid synovial tissue.     

Does α1-adrenergic blockade influence regional blood flow regulation in hearts with coronary artery occlusion?

Summary. The effects of selective α₁-adrenergic blockade with doxazosin on regional myocardial tissue blood flow was studied in anaesthetized cats with acute coronary artery occlusion. Reflex tachycardia was prevented by selective β₁-adrenergic blockade with atenolol and coronary perfusion pressure was kept constant by partial stenosis of the descending aorta. Administration of atenolol reduced cardiac mechanical work-load by its negative inotropic and chronotropic effects, and reduced myocardial tissue blood flow in normally perfused myocardium. This reduction was most pronounced in the endocardial half-layer of the myocardium adjacent to the ischaemic region. Administration of doxazosin in this situation clearly reduced peak systolic and coronary perfusion pressure. But when coronary perfusion pressure was raised to pre-administration values, measurements of regional blood flow revealed no changes either in ischaemic or non-ischaemic myocardium. Also, there was no sign of redistribution of blood flow between endocardial and epicardial tissue in any area. This study, therefore, indicates that α₁-adrenoceptors play a minor role in the regulation of coronary blood flow in normal myocardium as well as ischaemic myocardium.     

The Asn-291→Ser and Ser-477→Stop mutations of the lipoprotein lipase gene and their significance for lipid metabolism in patients with hypertriglyceridaemia

We examined 99 Finnish patients whose serum fasting triglycerides (TG) had exceeded 6.0 mmol L^?1, with special interest to their lipid, lipoprotein and post-heparin plasma lipase activities. The control group consisted of 75 healthy individuals. We also determined the frequency of the Asn-291→Ser and Ser-447→Stop mutations both in hypertriglyceridaemic (HTG) subjects and in control subjects. A total of 51 of the original 99 hypertriglyceridaemic patients still had TG > 6.0 mmol L^?1 when measured a second time. They are referred to as persistently hypertriglyceridaemic subjects (pHTG). The remaining 48 subjects had TG < 6.0 mmol L^?1 in the second measurement and are referred to as sporadically hypertriglyceridaemic subjects (sHTG). The allelic frequencies of the Ser-447→Stop mutation in the total HTG and sHTG groups were similar to the frequencies present in the control group, but lower in pHTG patients compared with the control group (0.049 vs. 0.153, χ² = 6.63, P < 0.05). The Asn-291→Ser mutation was more frequent in HTG group than in the control group (0.0606 vs. 0.013, χ² = 4.86, P < 0.05). This difference was due to the higher frequency of the minor allele of Asn-291→Ser in the cohort with persistent hypertriglyceridaemia compared with the control group (0.088 vs. 0.013, χ² = 8.00, P < 0.01 ). The highest frequency (0.114) of the minor allele of Asn-291→Ser was found in type 2 diabetic patients with persistent hypertriglyceridaemia. The carrier status of Asn-291→Ser or Ser-447→Stop did not predict either post-heparin plasma lipoprotein lipase (LPL) activities or lipid and lipoprotein levels in any of the groups studied. Our data suggest that overproduction of very low-density lipoproteins (VLDL) is a more important cause of hypertriglyceridaemia in the Finns than is the LPL deficiency.     

Primary hyperparathyroidism or hypercalcaemia of malignancy?

The introduction of two-site immunometric assays measuring intact parathyroid hormone (PTH) and radioimmunoassays measuring PTH-related peptide (PTH-RP) have simplified the evaluation of patients with hypercalcaemia. We present a 63-year-old man with recurrent hypercalcaemia after surgical treatment for primary hyperparathyroidism 3 years previously. PTH measured with a mid-region radioimmunoassay gave normal values, at the same level as during his primary hyperparathyroidism. Intact PTH was, however, clearly suppressed, and he had a highly elevated level of PTH-RP. This suggested that he had humoral hypercalcaemia of malignancy. The patient died after 2 months, and at autopsy an adenocarcinoma of the pancreas with no skeletal metastases was found.