Jet-impingement heat transfer in gas turbine systems.

A review of jet-impingement heat transfer in gas turbine systems is presented. Characteristics of the different flow regions for submerged jets--free jet, stagnation flow, and wall jet--are reviewed. Heat transfer characteristics of both single and multiple jets are discussed with consideration of the effects of important parameters relevant to gas turbine systems including curvature of surfaces, crossflow, angle of impact, and rotation.

Efficacy and safety of a new HMG-CoA reductase inhibitor, atorvastatin, in patients with hypertriglyceridemia.

OBJECTIVE: To assess the lipid-lowering effect of atorvastatin (a new 3-hydroxy-3-methylglutaryl coenzyme A [HMG-CoA] reductase inhibitor) on levels of serum triglycerides and other lipoprotein fractions in patients with primary hypertriglyceridemia, determine if atorvastatin causes a redistribution of triglycerides in various lipoprotein fractions, and assess its safety by reporting adverse events and clinical laboratory measurements. DESIGN: Randomized double-blind, placebo-controlled, parallel-group, multicenter trial. SETTING: Community- and university-based research centers. PATIENTS: A total of 56 patients (aged 26 to 74 years) with a mean baseline triglyceride level of 6.80 mmol/L (603.3 mg/dL) and a mean baseline low-density lipoprotein cholesterol (LDL-C) level of 3.07 mmol/L (118.7 mg/dL). INTERVENTIONS: Cholesterol-lowering diet (National Institutes of Health National Cholesterol Education Program Step I Diet) and either 5 mg, 20 mg, or 80 mg of atorvastatin, or placebo. MAIN OUTCOME MEASURES: Percent change from baseline in total triglycerides for three dose levels of atorvastatin compared with placebo. RESULTS: Mean reductions in total triglycerides between 5 mg, 20 mg, and 80 mg of atorvastatin and placebo after 4 weeks of treatment were -26.5%, -32.4%, -45.8%, and -8.9%, respectively. Mean reductions in LDL-C were -16.7%, -33.2%, -41.4%, and -1.4%, respectively, and very low-density lipoprotein cholesterol (VLDL-C) were -34.3%, -45.9%, -57.7%, and -5.5%, respectively. Similar mean changes in total apolipoprotein B (apo B) (-16.9%, -32.8%, -41.7%, and +1.0%), apo B in LDL (-14.8%, -29.8%, -42.0%, and -3.1%), and apo B in VLDL (-23.8%, -35.8%, -34.4%, and +11.7%) were observed. In addition, comparable mean changes in LDL triglycerides (-22.5%, -30.7%, -39.9%, and +3.9%) and VLDL triglycerides (-28.1%, -34.0%, -47.3%, and -10.8%) were seen. CONCLUSIONS: In atorvastatin treatment groups, total serum triglyceride levels decreased in a dose-dependent manner, reductions in the 20-mg and 80-mg groups were statistically significant (P < .05) compared with placebo. Atorvastatin did not cause a redistribution of triglycerides but consistently lowered triglycerides in all lipoprotein fractions. Atorvastatin was well tolerated.

Comparative effects of atenolol versus celiprolol on serum lipids and blood pressure in hyperlipidemic and hypertensive subjects.

Antihypertensive drugs may affect serum lipoprotein levels in mixed populations but data in hyperlipidemic patients are scanty. Atenolol versus celiprolol effects on serum lipoproteins were compared in 159 hyperlipoproteinemic hypertensive patients. This was a randomized, double-blind, parallel-group, positive-controlled multicenter trial with centralized lipoprotein laboratory and diet constancy monitoring. Blood pressure reduction and serum lipoprotein and apoprotein levels were monitored for 3 months. Both drugs reduced systolic and diastolic blood pressures. Atenolol had greater effects than celiprolol on diastolic pressure, but effects on systolic blood pressure were not different. Patients receiving atenolol had lower serum high-density lipoprotein cholesterol levels and higher low-density lipoprotein/high-density lipoprotein cholesterol ratios, whereas patients treated with celiprolol showed no contrasting changes. These differences in lipoprotein levels between drug treatment groups were statistically significant at weeks 9 and 12. The difference between drug treatments was also significant if the values of the 9- and 12-week visits were averaged. Patients taking atenolol had statistically significantly higher serum levels of total cholesterol, triglycerides and apoprotein B at 9 weeks. These divergent directional changes were consistent throughout and statistically significantly different between drugs.

Safety and tolerability of metoprolol OROS in hypertension treatment.

One hundred twenty-six patients with mild to moderate hypertension responsive to beta-adrenergic blocking agents--alone or in combination with other antihypertensive drugs--entered this open-label, multicenter study designed to evaluate the safety and tolerability of metoprolol OROS (metoprolol fumarate). Metoprolol OROS was given once daily for 14 weeks in doses ranging from 100 to 600 mg. Satisfactory blood pressure control was achieved by 85% of the patients at doses between 100 and 400 mg. Mean diastolic blood pressure was maintained at or below 90 mm Hg. Adverse reactions were experienced by 29% of the patients; most of these reactions were mild or moderate, and none was unexpected for treatment with a beta-blocker. Only three patients withdrew because of adverse reactions. The results of this study indicate that metoprolol OROS given once daily is safe and well tolerated.

The treatment of moderate to severe hypertension with ACE inhibitors.

Quinapril, when given as initial monotherapy or in addition to diuretics, was extensively evaluated in patients with moderate to severe hypertension, defined as sitting diastolic blood pressure (DBP) greater than or equal to 105 mm Hg with concomitant diuretic therapy or greater than or equal to 110 mm Hg during placebo baseline. In four double-blind, comparative trials and a subset analysis from a placebo-controlled study, 368 patients were treated with quinapril, and 338 patients were treated with comparative therapies (i.e., captopril, enalapril, or placebo). In three studies, quinapril was given in addition to diuretics, and in one study nonresponders received optional atenolol. Two studies assessed quinapril as first-line monotherapy, with nonresponders receiving hydrochlorothiazide in one study. Quinapril dosages ranged from 10 to 40 mg/day, with some patients receiving up to 80 mg/day. Quinapril effectively reduced blood pressure in patients with moderate to severe hypertension either as first-line monotherapy or when given concomitantly with a diuretic or a beta-blocker. Quinapril was comparable in efficacy to enalapril, and in several analyses quinapril was significantly more efficacious than captopril (p less than 0.05). Quinapril was well tolerated, and the incidence of adverse events was comparable with or less than that of captopril or enalapril.

The myth of the low anion gap.

Sixty-seven thousand seven hundred forty consecutive sets of electrolyte levels measured at the Massachusetts General Hospital were reviewed, and their anion gaps were calculated. A low anion gap (less than 8 mEq/L) was found in 304 patients (0.8%). Repeatedly low anion gaps were found in only 19 patients. Eight patients were hypoalbuminemic, and eight were hyponatremic. For the entire population, there was a positive correlation between sodium concentration and anion gap. The average anion gap was 16.25 mEq/L. The most common cause of a low anion gap was presumptive laboratory error.

The Harvard Cooperative Stroke Registry: a prospective registry.

Data from 694 patients hospitalized with stroke were entered in a prospective, computer-based registry. Three hundred and sixty-four patients (53 percent) were diagnosed as having thrombosis, 215 (31 percent)as having cerebral embolism 70 (10 percent) as having intracerebral hematoma, and 45 (6 percent) as having subarachnoid hemorrhage from aneurysm or arteriovenous malformations. The 364 patients diagnosed as having thrombosis were divided into 233 (34 percent of all 694 patients) whose thrombosis was thought to involve a large artery and 131 (19 percent) with lacunar infarction. Many of the findings in this study were comparable to those in previous registries based on postmortem data. New observations include the high incidence of lacunes and cerebral emboli, the absence of an identifiable cardiac origin in 37 percent of all emboli, a nonsudden onset in 21 percent of emboli, and the occurrence of vomiting at onset in 51 percent and the absence of headache at onset in 67 percent of hematomas.