Effect of gemfibrozil on erythrocyte membrane lipids in geriatric patients

Twenty geriatric patients with primary or secondary hyperlipidemia and suffering from various other diseases received for three weeks once daily 900 mg gemfibrozil. The hyperlipidemia had not been treated before, and a cholesterol-reduced diet did not succeed in lowering total cholesterol below 6.75 mmol/l (260 mg/100 ml) and serum triglycerides below 1.97 mmol/l (175 mg/100 ml). The purpose of this study was to analyze the lipid composition of the erythrocyte membrane, serum lipids and rheological parameters before and after the therapy. Mean serum total cholesterol and triglyceride content decreased significantly by 16.3% (p less than 0.05) and 35.2% (p less than 0.01) on average, respectively. Aggregation of thrombocytes and of erythrocytes, thrombin time and partial thromboplastin time slightly varied during the three weeks' treatment, but without statistical significance. The content of total long-chain saturated fatty acids in the phospholipid fraction of the erythrocyte membrane decreased slightly from 41.3% to 40.9% (p less than 0.05), whereas the total w6-unsaturated fatty acids without the precursor linoleic acid increased by about the same extent from 15.66% to 16.0% (p less than 0.05). The molar ratio of phospholipid to cholesterol content decreased significantly (p less than 0.01) due to a reduced phospholipid content at the end of the therapy. In conclusion, in addition to reducing the serum lipids, gemfibrozil slightly effects the lipid composition of erythrocytes, but the effects of the varied concentrations of long-chain saturated and long-chain w6-unsaturated fatty acids in the phospholipid fraction on membrane fluidity might be compensated, at least partly, by the decrease of the ratio of membrane phospholipid to cholesterol.

Decrease of cholesterol concentration in human erythrocyte ghosts in old age

The lipid composition of the erythrocyte membrane ghosts of 95 relatively healthy elderly subjects was compared between four age groups: 70 to below 75 years (I), 75 to below 80 (II), 80 to below 85 (III) and 85 to below 90 years of age (IV). The molar ratio of phospholipid to cholesterol (PL/CH) in the erythrocyte ghosts increased with advancing age. Whilst PL levels did not change significantly, a decrease of membrane cholesterol was found. Therefore, the red cell membrane cholesterol seems to parallel the well-known pattern of variation of mean plasma total cholesterol and LDL cholesterol concentrations with age: an increase to a maximum in the sixth decade of life, and a decline thereafter. The processes which are responsible for these changes in cholesterol level with age have not been delineated. However, the findings suggest that one might get different results in studies of age-dependent membrane lipid alterations if rough age group divisions are made (below 30 years of age vs. over 70 years) or to subdivide the group of the elderly.

Blood coagulation factors in the elderly

To investigate causes of the age-dependent increase of thromboembolic events, plasma coagulation parameters were determined in healthy elderly blood donors in comparison with young, and elderly diseased blood donors. Partial thromboplastin and thrombin clotting times were slightly shortened, whereas prothrombin and reptilase clotting times were unaltered. Plasma concentration of clotting factors like F I, VII, VIII: C, X, HMW-kininogen and prekallikrein were increased, whereas the coagulation inhibitor antithrombin III was decreased. Concerning fibrinolysis, plasminogen and alpha-2-antiplasmin were not affected by age, but plasminogen activators in the euglobulin fraction were lower. This shift in the pattern of coagulation factors favors enhanced fibrin formation and delayed fibrinolysis in the elderly. Higher intermediary products demonstrate that activation of coagulation and fibrinolysis happen more often in elderly healthy people. Together with blood stasis and vessel wall damage, this shift of the hemostatic balance contributes to a higher incidence of thromboembolic disorders in the aged.

SEM studies on age related changes in the surface structures of rat hairs

In albino rats of four age groups (male and female; 1, 6, 12 and 36 months) telogen hairs of the back were investigated in scanning electron microscopy at defined locations. The length of the cuticular 'scales' as well as the thickness of the hair shaft decreased significantly in the 36 month group of both sexes. In addition the scales of this group had irregular contours, cracks and spindle shaped inclusions.

Erythrocyte membrane changes associated with nutrition and aging--the role of plasmalogens

Fatty aldehyde dimethylacetals (DMA) derived from human plasma and red cell plasmalogens of 20 female and 20 male donors, aged 70 years and over, and of 17 younger ones (12 male, 5 female), were measured as part of total phospholipid fatty acid methyl esters and DMA. There were no statistically significant changes in the hexadecanal DMA fractions of erythrocyte membranes with respect to donor age. In contrast, small degrees of correlation, though statistically significant, indicate a stochastic decline with donor age of erythrocyte octadecanal DMA and of plasma-derived hexadecanal DMA and octadecanal DMA levels. It is concluded that in the context of age-related changes not only the plasmalogen content of biomembranes has to be considered. Because of the sensitivity of plasmalogens to autoxidation, effects of oxidative damage and defense on membrane architecture, the degree of plasmalogen domain formation with its implication on membrane functions and the mechanisms regulating membrane turnover have to be also assessed.

[Geriatric day clinics and rehabilitation]

If the present development of our population is not to result in a continued increase in care-requiring elderly people, the building and expansion of geriatric rehabilitation institutions is a matter of urgency. Numerous studies, some of which carried out in our own country, show how successful geriatric rehabilitation can be. Prerequisites are, apart from appropriately equipped facilities, the proper selection of those requiring care, adequate numbers of properly qualified personnel, and early initiation of any treatment needed. Thus, 70 to 80% of those originally scheduled for admission to an old persons' nursing home can be enabled to live more or less independently at home. Apart from geriatric hospitals, geriatric day clinics offer optimal possibilities for rehabilitation. They combine therapeutic effectiveness and economy with the advantage that, during treatment, the elderly person is not completely taken out of his familiar surroundings, which results in an improvement in his motivation to get well again quickly. At the same time, complicating diseases, such as, for example, diabetes mellitus, can be treated under conditions closely similar to those of the patient's subsequent day-to-day situation. In this sense, geriatric day clinics are not only desirable, but urgently needed institutions.

Pharmacokinetics of ranitidine in geriatric patients with multiple diseases

Ranitidine pharmacokinetics was measured after intravenous administration of 50 mg of the drug in 18 geriatric patients suffering from multiple diseases. Elimination half-life was prolonged (3.05 +/- 0.58 h) and total clearance was reduced (282 +/- 97 ml/min) as compared to the results of studies on normal younger persons by other investigators. In comparison to other studies on healthy elderlies, the pharmacokinetic parameters of ranitidine were only slightly different. Statistical analyses showed correlations of pharmacokinetic parameters of ranitidine with creatinine clearance, serum creatinine, uric acid concentration and alkaline phosphatase activity. These results disclose that reduced creatinine clearance or serum creatinine concentration in the upper normal range, for example, might serve as indicators for a possible dose reduction of ranitidine to prevent unnecessary overmedication in elderly patients.

Pharmacokinetics of tiaprofenic acid in geriatric patients with ischemic heart disease

The serum levels of tiaprofenic acid were determined by HPLC in 20 geriatric patients with ischemic heart disease, and the pharmacokinetic parameters were calculated. The results indicate that in geriatric patients the drug does not accumulate when given at a dose of 300 mg twice a day. Sufficient plasma levels are reached and the short terminal phase half-life prevents accumulation. The electrolyte balance was examined during the 7 days of treatment, and no change in sodium and potassium levels in the serum or in urine were observed. Weight as well as blood pressure of the patients remained constant, so that an increased development of edema, especially with regard to the existing ischemic heart disease of the patients, could be excluded. The results of our study indicate that tiaprofenic acid at the employed dosage is suitable for the therapy of arthritis in geriatric patients suffering from ischemic heart disease, without accumulation of the drug or the development of edema.

Pharmacokinetics of triamterene in geriatric patients--influence of piretanide and hydrochlorothiazide

Pharmacokinetics of triamterene (single oral dose of 50 mg) and its pharmacologically active metabolite (OH-TA-ester) were determined in 20 geriatric patients with multiple diseases. Mean peak concentration of triamterene was increased in the elderly patients compared with the data of young healthy volunteers. Coadministration of piretanide seems to lower the mean plasma concentration (AUC) and the mean concentration after 24 h of triamterene as compared with the coadministration of hydrochlorothiazide.

Clearance of heterologous, homologous and damaged homologous erythrocytes by the isolated perfused rat liver

Homologous and autologous rat erythrocytes, human erythrocytes as well as glutaraldehyde-treated and hemolysed homologous red blood cells suspended in an isotonic, buffered saline, free of immunoglobulins were perfused through the isolated rat liver. The mononuclear phagocyte system of the liver (mainly Kupffer cells) was able to recognize damaged rat and heterologous human erythrocytes and to sequester them by a direct membrane-erythrocyte mechanism. Hemoglobin and homologous and autologous rat erythrocytes were not sequestered or only to a minor extent. High sequestration rates are reflected by an increased energy demand with subsequent increase of the lactate-pyruvate and beta-hydroxybutyrate-acetoacetate-quotient.

Steady-state kinetics of bezafibrate retard in hyperlipidemic geriatric patients

The pharmacokinetics of a slow-release formulation of bezafibrate were investigated under steady-state conditions in 19 hyperlipidemic patients between the age of 61 and 87 years and compared to the kinetics in 20 healthy volunteers (age 19-42 years). Maximum serum levels were 1.6-fold higher in the elderly, which was partly due to a diminished renal clearance caused by the reduction in renal function (CLCR 23-81 ml/min) and partly due to a decrease in extrarenal clearance (probably hydroxylation and hydrolysis). Evidence for the additional decrease in extrarenal clearance was provided by the greater decline in total drug clearance than would be anticipated from a mere reduction in glomerular filtration. Thus, dose adjustment of slow-release bezafibrate in elderly patients cannot be based merely on creatinine clearance. In general, it is recommended that bezafibrate retard is substituted by a reduced dose of normal-release bezafibrate below a creatinine clearance of 60 ml/min.

High-performance liquid chromatographic method for the determination of alpha-amanitin and phalloidin in human plasma using the column-switching technique and its application in suspected cases of poisoning by the green species of amanita mushroom (Amanita phalloides)

A reversed-phase high-performance liquid chromatographic assay has been developed for the simultaneous determination of alpha-amanitin and phalloidin in human plasma. The procedure is based on the enrichment of the toxins on a pre-column, followed by the transfer of both compounds in a foreflush mode to the analytical column. alpha-Amanitin and phalloidin can be quantified reliably down to a minimum concentration of 10 ng/ml in plasma (relative standard deviation less than 10%). An alternative method is recommended for hepatic coma patients.