Associations of selected medications and visual function: the Beaver Dam Eye Study.

AIM: To investigate association of drug use and visual function. METHODS: A cross sectional population based study was carried out on participants in the 1993-5 examination phase of the Beaver Dam Eye Study. All drugs in current use by study participants were recorded. Performance based and self assessed visual functions were obtained at the time of the study evaluation. The main outcome measure was the relation of levels of visual functions by use of specific drugs. RESULTS: Many classes of drugs were associated with decreases in at least two performance based visual functions. For example, high blood pressure drugs were significantly associated with poorer best corrected visual acuity, poorer near vision, and poorer contrast sensitivity (p<0.001 for all). Patterns of association for self assessed visual functions were not as strong. However, use of glaucoma drops and benzodiazepines were associated with poorer self assessed visual functions in most circumstances cited. CONCLUSIONS: Many commonly used medications are inversely associated with visual functions in a middle and older aged population. This may influence the ability to perform complex tasks and quality of life.

The saline solution bag as a compensating filter.

For certain radiographic procedures, extremes in tissue composition and/or thickness can result in a poor quality image. There exists, however, a practical approach to adjust for tissue extremes by using a saline solution bag as a compensating filter. By applying this technique, radiographic image quality can be improved.

High technology: miracle or malady for patient care.

Trends in medicine in the United States today are toward a more widespread application of high technology equipment and procedures. The patient can perceive these new technologies as both miracles and maladies in their health care delivery. While a benefit to the treatment of the disease process is usually very clear, the impact on the person as a whole is often forgotten. The article is intended to focus on the impact of high technology on the patient as a person.

Erythrocyte membrane sialic acids in primary and secondary hypertension in man and rat.

Sialic acids of erythrocyte membranes (erythrocyte 'ghosts') and blood plasma were studied in patients with essential or chronic renal hypertension, and in spontaneously hypertensive rats (SHR). The total content of sialic acids in erythrocyte membranes (determined by thiobarbituric-acid assay) was around 100 mumol/g protein in both the hypertensive patients and controls, there being no difference between the three groups. Similarly total sialic-acid content of plasma did not differ between the hypertensive patients and controls, being around 2 mmol/l. Although total membrane sialic acid was unchanged, the sialic-acid content of glycolipids extracted from erythrocyte membranes was 17% greater (P less than 0.001) in patients with essential hypertension than in renal hypertensive patients and controls (22.1 +/- 0.5 mumol/g protein v. 18.2 +/- 0.8 and 18.9 +/- 0.8, respectively). Sialic acid in plasma glycolipid did not differ between the patient groups. The animal study revealed no differences between total--or glycolipid--sialic-acid content in plasma and erythrocyte membrane in SHR and normotensive rats. The finding of an increase in the sialic-acid content of erythrocyte membrane glycolipid in essential hypertension is in agreement with recent studies demonstrating structural abnormalities in hydrophobic regions of erythrocyte membrane, and is considered a manifestation of membrane glycolipid alteration in primary hypertension.

[Role of membrane-bound calcium in the changes of ion permeability and Na+, 5+ and ATPase activity of the erythrocytes in hypertension]. / O roli kal'tsiia, sviazannogo s membranoi, v izmenenii ionnoi.

The content of calcium bound to the erythrocyte membrane and the effect of intracellular calcium concentration on the activity of Na+, K+-ATPase in the reconstituted erythrocytes were studied in 20 patients with essential hypertension and in 20 individuals with normal pressure. In incubation of the erythrocytes in a solution containing EDTA much more calcium is removed from the outer surface of their membrane in patients with essential hypertension than in the control group (60 +/- 5 mEq/l and 41 +/- 3 mEq/l, respectively). When the intracellular calcium concentration varies from 0 to 500 mumol/l, which corresponds to a rise in the free calcium (Ca2f+-3) concentration to 41 mumol/l, a difference in the changes of Na+, K+-ATPase activity of the reconstituted erythrocytes is noted. When intracellular calcium concentration is 50 mumol/l (Ca2f+-3 mumol/l), ATP-ase activity in patients with essential hypertension is 21% less than that in individuals with normal pressure (P less than 0.005). The authors explain the difference in the kinetics of Na+, K+-ATPase changes by the different degree of calcium depletion of the inner surface of the erythrocyte membrane in relatively low Ca2f+ values in the internal medium. The data obtained are evidence of the altered calcium-binding capacity of the erythrocyte membrane, which may cause the increased permeability of the erythrocyte membrane to sodium and potassium ions in patients with essential hypertension, which the authors had revealed earlier. The authors consider the revealed changes to be a fragment of a more extensive membrane defect which may be the principal cause of activation of the servomechanisms which maintain arterial pressure.

[Disruption of erythrocyte membrane permeability for sodium and potassium ions in hypertension]. / Dannye o narushenii pronitsaemosti membrany éritrotsitov dlia ionov natriia i kaliia pri gipertonicheskoi bolezni

The kinetics of Na22 efflux from the erythrocytes and K42 accumulation by the erythrocytes in patients with essential hypertension and in normotensive persons was studied. Sodium efflux from the erythrocytes into a normal medium was found to be significantly accelerated in hypertensive patients, and their rate constant of Na/Na exchange in the erythrocytes has a higher value (1.61 +/- 0.39 mol.1(-1) min.-1 versus 0.56 +/- 0.08 - 10(-6) mol. 1(-1).min. -1). The difference is statistically significant only under active transport inhibition with ouabain. K42 accumulation by the erythrocytes is slower than in normotensive indifiduals. The observed changes in the transport of cations are attributed by the authors to an increased passive permeability of the erythrocytic membrane in hypertonics. The latter is interpreted as a fragment of a more general defect of the cell membrane function that may be the cause of activation of the mechanisms that maintain a high arterial pressure.