Biomedical subjects

E R Block

Publications and source records attributed to E R Block.

111 records · Page 7Linked to original sources

PubMed1972

Pharmacological studies with 5-fluorocytosine.

A cylinder plate bioassay for 5-fluorocytosine (5-FC) is described which permits determination of 5-FC concentrations in biological fluids in the presence of amphotericin B. Using this assay, we determined serum concentrations in 12 patients after a single dose of drug and in 8 patients receiving daily 5-FC at 6-hr intervals (4 to 120 days). Drug was detectable in serum as early as 0.5 hr and concentrations were measurable as long as 24 hr after a dose, regardless of renal function. Peak concentrations occurred 6 hr after the initial drug dose, but were seen between 1 and 2 hr after a dose in all patients receiving a minimum of 4 days of therapy. Mild to moderate renal impairment produced marked increases in peak 5-FC concentrations in the serum of a group of eight patients on three different dosage schedules. Five patients were studied before and after amphotericin B-induced renal insufficiency. Peak concentrations increased from 14 to 142% concomitant with the change in renal function. Parallel studies in rabbits confirmed the results in our patients. 5-FC half-life in the serum of 10 rabbits increased from 3.35 +/- 0.27 to 24.63 +/- 0.70 hr after experimentally induced acute renal failure. Concentrations of 5-FC in the cerebrospinal fluid of five patients ranged from 17 to 62 mug/ml and were 74.4 +/- 5.6% of simultaneously determined serum concentrations. The effect of renal function on 5-FC concentrations in cerebrospinal fluid was similar to that seen with serum.

Adult↗

PubMedDate not supplied

Carbonic anhydrase inhibition in glaucoma: hazard or benefit for the chronic lunger?

Carbonic anhydrase inhibitors, of proven value in the longterm management of glaucoma, have a number of troublesome side effects, most of which are well-known. However, their potential hazards to patients with chronic obstructive lung disease have received little attention. The author reviews the physiological effects of carbonic anhydrase inhibition on carbon dioxide metabolism and the implications for the chronic lung patient. The untoward pulmonary complications associated with the use of carbonic anhydrase inhibitors are of particular importance to ophthalmologists, since chronic lung disease and glaucoma, both common disorders in the elderly, frequently coexist in the same patient.

Acetazolamide↗

PubMedDate not supplied

Vitamin E distribution and modulation of the physical state and function of pulmonary endothelial cell membranes.

Vitamin E, a dietary antioxidant, is thought to incorporate into the lipid bilayer of biological membranes. We evaluated the lipid composition and distribution of [3H]-vitamin E in various membranes of pulmonary endothelial cells and determined whether vitamin E incorporation caused alterations in membrane structure and function in these cells. Following 6-, 12-, 18-, 24-, and 48-h incubation periods, vitamin E incorporation values were 3.0, 5.7, 6.9, 7.2, and 6.8 nmol/mg protein or 3.8, 7.3, 8.8, 9.2, and 8.7 nmol/mg phospholipid in mitochondrial membranes and 2.0, 4.4, 5.2, 5.3, and 5.0 nmol/mg protein or 3.5, 7.7, 9.1, 9.3, and 8.8 nmol/mg phospholipid in microsomal membranes, respectively. Vitamin E incorporation into the plasma membranes was greater than in mitochondrial and microsomal membranes after 12-, 24-, and 48-h incubations (18.9, 20.8, and 19.6 nmol/mg protein, respectively [P less than .001] versus mitochondria and microsomes or 12.2, 13.4, and 12.6 nmol/mg phospholipid, respectively [P less than .05] versus mitochondria and microsomes). The total phospholipid content, as well as the unsaturation index of the fatty acid content of these membranes, were in the same order, (i.e., plasma membrane greater than mitochondrial membranes and microsomal membranes). The physical state of the intact plasma membrane and the mitochondrial and microsomal membranes were measured by monitoring fluorescence anisotropies (rs) of the molecular probes, diphenylhexatriene (DPH) and trimethylamino-DPH (TMA-DPH). Vitamin E incorporation caused significant increases in rs for DPH (P less than .01) and TMA-DPH (P less than .01) in all three membranes compared to controls. Similar increases in rs values for DPH and TMA-DPH were observed in lipid vesicles prepared from these membranes. Following vitamin E incorporation, 5-hydroxytryptamine (5-HT) transport was measured as an index of plasma membrane function. Vitamin E incorporation resulted in an 18% reduction (P less than .05) in 5-HT uptake. These results indicate that vitamin E was distributed nonuniformly in endothelial cell membranes but resulted in comparable decreases in fluidity in all three membranes. In addition to its role as an antioxidant, vitamin E may alter the membrane physical state and modulate a variety of endothelial cell functions, including 5-HT transport.

Animals↗