Platelet membrane fluidity and aggregation of rabbit platelets

Aggregation of rabbit platelets from citrated plasma in response to ADP was directly correlated with platelet plasma membrane fluidity as determined by fluorescence depolarization measurements with the probe diphenylhexatriene. Rabbits were maintained for periods of 200 and 400 days on potentially hyperlipidemic diets (20% fat by weight) with varying levels of saturated and polyunsaturated fatty acids. Dietary variations were effective in modulating the mole percentage distribution patterns of the platelet phospholipid fatty acids. The major chemical control of membrane fluidity was the actual mass of unsaturated lipid in the cells and not simply the relative percentage distributions of such unsaturated fatty acids. Substantially higher phospholipid/protein ratios were observed upon analysis of platelets and platelet membranes from rabbits after 200- than after 400-day diet periods. Accordingly lipid structures were significantly more fluid in either whole platelets or membrane isolates at the end of the shorter diet period. The observations pertaining to the extent of aggregation and membrane fluidity are in consonance with the general role of membrane fluidity in controlling biological activity and support the concept that platelet aggregation is a membrane-associated phenomenon.     

Increased serum angiotensin-converting enzyme in chronic renal disease

Serum angiotensin-converting enzyme (SACE) was significantly elevated in 16 of 48 patients with various types of chronic renal disease not on hemodialysis [45.6 +/- (SD) 16.7 nmol/min/ml, p less than 0.001] and in 17 of 52 patients with chronic renal disease on maintenance hemodialysis (43.2 +/- 13.8, p less than 0.001) in comparison with 58 healthy adult controls (32.2 +/- 9.8). There was no significant relationship between SACE and renal function as indicated by serum creatinine and creatinine clearance, or the presence or absence of maintenance hemodialysis, except for a transiently increased elevation of SACE immediately post-dialysis due to hemoconcentration. There was a statistically insignificant positive correlation between SACE and 24-hour urinary protein excretion (r = 0.254, n = 21). Mean blood pressure measured in patients on maintenance hemodialysis was inversely related to SACE (p less than 0.05) following dialysis. Chronic renal disease irrespective of severity and therapy tends to be associated with elevated SACE and must be considered in the evaluation of sarcoidosis.     

Malignant lymphomas in a population at risk for acquired immune deficiency syndrome

Certain neoplasia are closely associated with acquired immune deficiency syndrome (AIDS). To evaluate this relationship the authors reviewed the occurrence of lymphomas in populations at high risk for AIDS; the study population included prisoners from New York State and nonprisoner intravenous drug abusers (IVDA). Non-Hodgkin's lymphoma was diagnosed in 16 prisoners, all of whom were IVDA, and four nonprisoner IVDA. The observed number of prisoners with non-Hodgkin's lymphoma (11) diagnosed between January 1, 1981 and December 12, 1984, significantly greater than the expected number (2.28) based on age adjusted incidence rates for the US population (P less than 0.001). The calculated average incidence rate for non-Hodgkin's lymphoma among New York State prisoners aged 20 to 49 years was 21.5/10(5) to 67.2/10(5), which was nearly sixfold to 18-fold higher than the general population. For prisoner IVDA, specifically, this incidence may be as high as 164/10(5), which represents a 40-fold increase in the relative risk compared with the general population. It is concluded that, non-Hodgkin's lymphoma is frequently a manifestation of AIDS among IVDA, and is the most common malignancy seen in IVDA with AIDS.     

Comparative anatomy of feline and canine gastric sling fibers

Investigation of the function of human sling fibers is not feasible with the use of technics currently available for animal experiments. Thus, this study examined the anatomy of the gastric sling fibers in 22 dogs and 16 cats to determine if either or both resemble that of the human. In both species, the gastric sling fibers hooked around the notch between the gastric fundus and distal esophagus, and traversed the stomach, anteriorly and posteriorly, parallel to the lesser curve, finally disappearing near the incisura angularis. A constrictor cardiac muscle was found at the upper limit of the sling fibers in both species. The muscularis propria of the distal esophagus of the dog was found to be striated. In contrast, smooth muscle was present in the distal esophagus of the cat. Furthermore, a vestibule, analogous to that described in man, was found in the cat but not in the dog. It has been postulated that the sling fibers play a role in the sphincteric mechanism of the distal esophagus. Our finding that the anatomy of the sling fibers and the distal esophagus in the cat resembles that of man suggests that it would be a more suitable model than that of the dog.     

In vivo H-1 spectroscopy in humans at 1.5 T

Water-suppressed and section-selective proton (hydrogen-1) magnetic resonance (MR) spectra were recorded from human brain, leg muscle, liver, and heart with a 1.5-T imager. Signal from water was well suppressed, and resonances from several metabolites were consequently seen. The spectra from brains of healthy volunteers (n = 5) showed resonances from N-acetylaspartate, glutamine, aspartate, phosphocreatine/creatine, choline, taurine, and glycine. In five large brain meningiomas, resonances from N-acetyl-aspartate and phosphocreatine/creatine were either not visible or markedly decreased in intensity. The spectra from leg muscles of healthy volunteers showed resonances from protons in saturated fatty acyl chains, whereas resonances from unsaturated fatty acyl chains predominated in spectra from leg muscles of two patients with spina bifida. The spectra from livers of three healthy volunteers showed resonances from aliphatic and aromatic amino acids, choline, carnitine, and both saturated and unsaturated fatty acyl chains, and spectra from hearts of six healthy volunteers showed major resonances from phosphocreatine/creatine and taurine and smaller resonances from amino acids and fatty acyl chains.     

Splenic abscess arising by direct extension from a perinephric abscess

A case of a perinephric abscess invading the spleen in a 25-year-old woman with bladder exstrophy is reported. Treatment utilized both percutaneous drainage and open surgery. Perinephric abscesses have not been previously reported to extend into the spleen.