Arterial effects of salt restriction in hypertensive patients. A 9-week, randomized, double-blind, crossover study.

OBJECTIVE: To investigate the hemodynamic effects of a moderately low-salt diet in a 9-week, randomized, double-blind, crossover study in 20 hypertensive, ambulatory patients. METHODS: All subjects followed a 9-week, low-salt diet. During this period, they received capsules containing either lactose or salt in 4-week treatment periods, separated by a 1-week washout period. Hemodynamic and biological parameters were evaluated on the day of randomization and at the end of weeks 4 and 9. We defined a low-sodium diet (LSD) as a salt-restriction period with lactose capsules, and a normal-sodium diet (NSD) as a salt-restriction period with capsular salt supplementation. RESULTS: Blood pressure was significantly lower during LSD compared with NSD. This fall in blood pressure was associated with a decrease in peripheral resistance in carotid and forearm circulation. Brachial artery diameter was larger during LSD whereas carotid artery diameter remained unchanged. The changes in brachial artery were: (1) not related to blood pressure changes; (2) positively related to age, and (3) negatively correlated with baseline intracellular sodium content. CONCLUSIONS: These results suggest that moderate low-salt restriction is capable of decreasing blood pressure and peripheral resistance in carotid and forearm circulation. The increase in brachial, but not carotid, artery diameter following salt restriction suggests a difference in salt dependence among different arteries.     

Scorpion sting: a management problem.

Admissions for scorpion sting in 1 year and deaths resulting from scorpion sting over 3 years were analysed. Features that indicated the severity of the clinical condition were identified. Pulmonary oedema and shock were the usual causes of death. Poor management of fluid therapy was responsible for the frequently unsatisfactory resolution of envenoming, especially when purified human plasma was used. The role of the scorpion antivenom used is questioned and controversy regarding the most appropriate sedative to use in the management of scorpion sting is still not resolved. An in-depth study of these management issues is urgently required.     

Brain enzyme levels in CSF after cardiac arrest and resuscitation in dogs: markers of damage and predictors of outcome

Levels of brain creatine kinase (CK), aspartate aminotransferase (ASAT), and lactate dehydrogenase (LD) in CSF after cardiac arrest were studied in dog models. Ventricular fibrillation cardiac arrest lasting 10 min or asphyxiation cardiac arrest lasting 0-10 min was followed by cardiopulmonary resuscitation and 96-h intensive care. Outcome was scored as neurologic deficit (0% = normal, 100% = brain death) and overall performance category (1 = normal, 5 = death). Both measures correlated with EEG return time after asphyxiation cardiac arrest, but not after ventricular fibrillation cardiac arrest. Peak activity of enzymes in CSF at 48-72 h post arrest correlated with outcome, and CK was the best predictor. Brain histopathologic damage score at autopsy 96 h post arrest correlated with CK level in CSF (r = 0.79, n = 39) and neurologic deficit (r = 0.70, n = 50). Ischemic neuronal changes occurred after ventricular fibrillation cardiac arrest of 10 min, and neuronal changes plus microinfarcts occurred after asphyxiation cardiac arrest of 1.5-10 min. Brain enzymes were decreased at 6 h post arrest in regions with worst histologic damage (gray matter of neocortex, hippocampus, caudate nucleus, cerebellum). Brain CK decreased further, ASAT remained low, and LD increased at 72 h after arrest. The temporal changes in CK level paralleled the temporal ischemic neuronal changes in the brain, and time to peak activity was unaffected by the severity of the ischemic insult. Peak activity of individual enzymes in CSF was determined predominantly by the brain concentration, but was also influenced by rate of decomposition. This "chemical brain biopsy method" represents a useful adjunctive tool to predict permanent, severe brain damage during comatose states after cardiac arrest and resuscitation.     

Follow-up of soluble interleukin-2 receptor levels after thymectomy in patients with myasthenia gravis.

Soluble interleukin-2 receptor (sIL-2R) levels were followed up after thymectomy by a quantitative immunoradiometric assay in 59 patients with myasthenia gravis (MG). Increased levels of sIL-2R were found in 30.5% of the patients before thymectomy. Serum levels were significantly higher in severely affected patients. Sequential sampling after thymectomy indicated a significant and progressive decline of sIL-2R levels within 2 years after surgery, which was well associated with clinical improvement or remission. The sIL-2R purified from sera of patients with MG had a molecular mass of 45 kDa as the normal sIL-2R. The decline after thymectomy of sIL-2R titers suggests a possible role of the thymus in the occurrence of sIL-2R in the periphery. Soluble IL-2R levels may represent a marker of disease severity in MG, which might be useful in the follow-up of individual patients.     

Acute changes in forearm haemodynamics produced by cigarette smoking in healthy normotensive non-smokers are not influenced by propranolol or pindolol

Summary The aim of the present study was to examine the effect of cigarette smoking in healthy non-smokers on blood pressure and forearm haemodynamics after acute oral administration of non-selective -adrenoceptor blockers with and without intrinsic sympathomimetic activity, viz. pindolol 15 mg and propranolol 80 mg. A preliminary study was done to compare cigarette smoking and sham smoking to evaluate the time-course of the haemodynamic effects of cigarette smoking. The second experiment was then carried out in the same six volunteers, according to a double-blind randomized placebo-controlled crossover design, to evaluate the possible effect of pre-treatment with -adrenoceptor blockers on blood pressure, heart rate and forearm haemodynamics (forearm blood flow, brachial artery diameter and brachio-radial pulse-wave velocity) measured at baseline, during smoking and every five minutes up to 1 h afterwards.No major difference from placebo in blood pressure or forearm haemodynamics was found and pre-treatment with beta-blockers did not prevent the acute vascular effects of cigarette smoking.