Observation of high enantioselectivity for the gas phase hydrogenation of methyl pyruvate using supported Pt catalysts pre-modified with cinchonidine

Pt supported on alpha-Al2O3, gamma-Al2O3 and SiO2 pre-modified with cinchonidine gives over 50% ee in the hydrogenation of methyl pyruvate to methyl lactate using gas phase reactants at 40 degrees C giving the first clear observation of high enantioselection at the gas/solid interface.

Social work practice with people with disabilities in the era of disability rights

Social workers, especially those in health care and rehabilitation systems, must consider practice changes necessitated by recent legislation and the growing activism of disability rights groups. The authors review essential elements of the emerging sense of both oppression and empowerment that is occurring for many people with disabilities and groups; consider key aspects of ADA and other perti nent legislation that place new emphases on the self-determination of people with disabilities; and discuss what implications changing practice roles might have for social workers' relationships and patterns of interaction with other professionals in medical, health care and rehabilitation settings. The authors outline a beginning effort at designing a conceptual framework that promotes practice that: (1) maximizes clients' involvement in exploring an expanded range of options and choices; (2) prepares clients to be more effective in dealings with professionals, bureaucrats and agencies that often do not understand nor appreciate their need for self-determination; and (3) at the organizing level, mobilizes and helps to empower groups of people with disabilities to consider policy and program alternatives that can improve their situation. This framework may also be useful in work with people who have other long term care needs, chronic conditions.

Diuretic therapy in congestive heart failure

The principal goals of treatment of the patient in heart failure are the relief of their symptoms and improvement in their prognosis. Of all antiheart failure drugs currently available, the diuretics are therapeutically superior in their efficacy in relieving clinical symptoms and signs. Whether administered intravenously or orally, all diuretics result in a substantial reduction in the raised pulmonary vascular pressures in combination with a small reduction in cardiac output. Diuretics stimulate release of renin with subsequent activation of the renin-angiotensin-aldosterone system, particularly if used in large doses, although their quantitative impact on the neuroendocrine profile at different stages of heart failure remains to be defined. In patients with mild heart failure, diuretics reduce plasma catecholamine concentrations, but their sympatholytic effects in more severe cases are unknown, as are their effects on the metabolically active tissues in these patients. Diuretic resistance can be circumvented by segmental nephron blockade with a combination of low-dose diuretics that simultaneously block sodium reabsorption in the proximal tubule, the loop of Henle, the distal tubule, and the collecting duct. Diuretics improve symptoms of breathlessness and signs of peripheral edema in patients with congestive heart failure in direct relationship to the induced diuresis. These benefits are frequently associated with a substantial improvement in patients' appreciation of quality of life and economic capacity. There are few adverse reactions to chronic diuretic therapy, but the serum electrolytes should be monitored for hypokalemia and hypomagnesemia. The impact of diuretics on prognosis of patients with congestive heart failure is unknown; however, diuretics have been a major ingredient of the therapies used in all the survival trials with vasodilators, angiotensin-converting enzyme inhibitors, and beta-blocking drugs. In addition to their clinical benefits, diuretics are the most cost-effective treatment of any single drug group currently available for the treatment of patients with congestive heart failure.

Diuretics in cardiovascular therapy: the new clinicopharmacological bases that matter

Diuretics in current use include early distal tubular (i.e., thiazide-type), loop (i.e., furosemide-type), and potassium-and-hydrogen-retaining substances. Available oral formulations of diuretics differ in terms of their renal excretory potency in man, as formally assessed through the effect of a single dose on 24-hour natriuresis in healthy subjects. The 2.5 mg formulation of the loop diuretic torasemide does not increase mean 24-hour natriuresis, and it is therefore considered a very-low-dose formulation. Amiloride 5 mg and torasemide 5 mg and 10 mg, which increase mean 24-hour natriuresis by less than 40%, are considered low-dose or low-potency diuretic formulations of diuretic substances. Hydrochlorothiazide 25 and 50 mg, furosemide 40 and 80 mg, and torasemide 20 mg, which increase mean 24-hour natriuresis by more than 40%, are considered high-dose or high-potency formulations. A rebound in natriuresis follows the early-after-dosing increase in this variables caused by loop diuretics; hence many oral formulations of loop substances are less potent natriuretics than most oral formulations of thiazide-type diuretics. Hydrochlorothiazide 25 mg and furosemide 80 mg have similar natriuretic potencies. During once-daily administration of diuretic formulations of diuretics to subjects without edema and normal renal function, the increases in 24-hour natriuresis and diuresis that follow the first dose disappear or attenuate markedly. This is due to neuroendocrine reactions to diuretic-induced sodium loss and its attendant hemodynamic shifts. Some of these reactions, e.g. the increase in plasma aldosterone that takes place, account for an elevation in kaliuresis that occurs during once-daily treatment with a high-dose formulation of a thiazide-type diuretic. Common fixed-dose combinations of a thiazide-type or a loop diuretic and a potassium-and-hydrogen-retaining substance generally do not change kaliuresis, but they increase natriuresis strikingly. Thiazide-type and loop diuretics decrease and increase calciuresis respectively; none of these actions wanes during prolonged administration. Plasma renin activity and aldosterone do not rise in response to very-low-dose formulations of loop diuretics taken once daily. Glomerular filtration rate tends to fall in the course of once-daily administration of high-dose formulations of diuretics, but not during prolonged once-daily treatment with very-low-dose formulations of loop diuretics.

Hemodynamic differences between metoprolol and carvedilol in hypertensive patients

Resting hemodynamics were measured before, at 2 and 24 h after the first dose, and after 4 weeks of monotherapy with either metoprolol or carvedilol in a randomized single-blind study. We analyzed results from 24 hypertensive patients (30-68 years of age) with adequate blood-pressure lowering on monotherapy. Acutely, both drugs lowered systolic blood pressure and heart rate. Whereas metoprolol reduced cardiac output and increased both systemic and femoral artery resistance, carvedilol did not alter cardiac output but led to reductions in the systemic and regional resistances. After 4 weeks of therapy, cardiac output remained reduced and vascular resistances increased in the metoprolol group, whereas in carvedilol patients cardiac output continued to be unchanged and the trend for vascular resistances to be decreased persisted. Acutely and chronically the differences in the hemodynamic effects of the two medications were statistically significant. The study results indicate that carvedilol's vasodilatory action is not subject to tolerance development. Chronic afterload reduction associated with the decrease in systemic vascular resistance may lead to additional savings in myocardial oxygen consumption, a beneficial feature particularly in those patients with concomitant ischemic heart disease. It may also have a favorable influence on concentric cardiac hypertrophy and changes in the walls of arteriolar resistance vessels.

Comparison of the hemodynamic effects of metoprolol and carvedilol in hypertensive patients

Metoprolol and carvedilol are widely used in the treatment of hypertension, but no randomized comparison of their hemodynamic activity has been previously reported. Their comparative effects on heart rate, systemic blood pressure, and echocardiographically determined aortic and femoral artery blood flow were measured at rest and at 2 and 24 hours after the first dose of each drug, and again after 4 weeks of sustained monotherapy in 12 male and 12 female patients, aged 36-68 years with uncomplicated sustained hypertension according to a randomized single-blind protocol. Nine patients in each drug group achieved the target diastolic blood pressure of < 90 mmHg on the initial doses of each drug; this was achieved in the remainder following doubling of each dose. Neither drug occasioned withdrawal of any patient due to adverse reactions. Both drugs significantly reduced heart rate, although the reduction at 2 hours was significantly greater after metoprolol than after carvedilol. Both drugs reduced systolic pressure throughout the study; the reduction at 2 hours was significantly greater after carvedilol than after metoprolol. In contrast, the diastolic blood pressure was persistently reduced only by carvedilol. The cardiac output, determined as the aortic systolic blood flow, after carvedilol was not significantly different from pretreatment values throughout the study but was significantly reduced in the metoprolol-treated patients at each point of measurement. After metoprolol the systemic and femoral vascular resistances derived from conventional formulae were consistently and significantly increased over pretreatment values throughout the study and were significantly greater than in the carvedilol group at all measurement points. The hemodynamic differences between these two beta-blocking drugs may be explained by the additional vasodilator activity of carvedilol associated with its alpha 1-adrenoceptor blocking activity. The long-term clinical and prognostic implications of these pharmacodynamic differences between beta-adrenoceptor antagonists with and without additional vasodilator activity in the treatment of hypertensive patients remain to be determined.

Congestive heart failure. Towards a comprehensive treatment

Heart failure constitutes an increasing health hazard with major demands on health care resources. Recent major advances in drug treatment have yet to be translated into increased survival of heart failure patients in the community at large. Failure of diagnosis is a major factor in delaying early and adequate treatment. Echocardiography probably provides the most reliable and inexpensive instrument to confirm the diagnosis and pinpoint the mechanical components of the syndrome. The targets for therapeutic intervention may be categorized (i) haemodynamic, neuroendocrine and metabolic disorders (ii) symptoms and quality of life, (iii) morbidity and mortality risks. Symptoms and quality of life are the prime concerns of the physician in the treatment in the individual patient. Selection of anti-heart failure drugs used should be based on knowledge of the impact on the pathophysiological disorders and on the morbidity and mortality risks. Diuretics, vasodilators and ACE-inhibitors are now accepted as standard treatment, particularly when used in combination. Controversy continues to surround the efficacy of digitalis glycosides; they improve symptoms in some patients but their impact on morbidity and mortality risks is still uncertain. Even with standard treatments, may practical therapeutic questions remain, one of which is what is the most efficacious dose of each anti-heart failure drug which, when used in combination, will give the maximum improvement in quality of life and greatest extension of survival? Despite available treatment with diuretics, digitalis, vasodilators and ACE-inhibitors, the morbidity and mortality risks of congestive heart failure remain high. None of these drug groups significantly modulates the excessive excitation of the sympathoadrenal system, one of the two major neuroendocrine hazards of heart failure. For this reason, amongst the many newer drugs in development, the beta-adrenoceptor antagonists hold considerable promise as the next step towards a more comprehensive treatment of congestive heart failure.

Reoperation for recurrent metastatic brain tumors

Results of reoperation in 48 patients who developed recurrent brain metastases between January 1984 and April 1993 are presented. Median time from first craniotomy to diagnosis of recurrence (time to recurrence) was 6.7 months. Median Karnofsky performance scale (KPS) score prior to reoperation was 80. Recurrence was local in 30 patients, distant in 16 patients, and both local and distant in two patients. Median survival time after reoperation was 11.5 months. There were no operative mortalities. Multivariate analysis revealed that presence of systemic disease (p = 0.008), KPS scores less than or equal to 70 (p = 0.008), time to recurrence of less than 4 months (p = 0.008), age greater than or equal to 40 years (p = 0.51), and primary tumor type of breast or melanoma (p = 0.028) negatively affected patient survival time. These five factors were used to develop a grading system (Grades I-IV). Patients categorized in Grade I had a 5-year survival rate of 57%, whereas the median survival time of patients in Grades II, III, and IV was 13.4, 6.8, and 3.4 months, respectively (p < 0.0001). Overall, 26 patients developed a second recurrence after reoperation. Seventeen patients underwent a second reoperation, whereas nine did not. Patients undergoing a second reoperation survived a median of 8.6 additional months versus 2.8 months for those who did not (p < 0.0001). This study concludes that reoperation for recurrent brain metastasis can prolong survival and improve quality of life. A second reoperation can also increase survival. Five factors influence survival: status of systemic disease, KPS score, time to recurrence, age, and type of primary tumor. The grading system using these five factors correlates with survival time. Reoperation should be approached with caution in Grade IV patients because of their poor prognosis.