Effects on the buoyant density of rabbit platelets of ADP and agents that increase the concentration of cyclic AMP

Rabbit platelets were aggregated by adenosine diphosphate (ADP), allowed to deaggregate and then separated into density subpopulations by centrifugation through discontinuous Stractan density gradients. Although ADP causes little or no release of the contents of the amine storage granules of rabbit platelets, ADP caused a decrease in platelet density as compared with control platelets subjected to the same procedures except for exposure to ADP. The density change persisted for at least four hours. The apparent size of platelets stimulated with ADP increased initially, but returned to control values during a one-hour period. A similar decrease in platelet density was observed with an albumin density gradient. Under conditions in which aggregation did not occur in response to ADP with ethylenediaminetetraacetic acid (EDTA) in the medium, little or no decrease in platelet density was observed. Agglutination with polylysine did not change platelet density. Thus, not only agents such as thrombin and plasmin that cause the release of the contents of the platelet granules decrease platelet density, but ADP also has this effect. Platelets would be exposed to all of these stimuli during thromboembolic processes, and their effect on platelets may account for the decrease in platelet density observed previously in experiments with rabbits with indwelling aortic catheters. Agents that increase the concentration of cyclic AMP (cAMP) in platelets (PGE1, adenosine, dibutyryl cAMP, forskolin, and papaverine) also decreased platelet density. This effect persisted when the platelets were washed and resuspended in fresh medium and was also demonstrable in plasma. Platelet size was gradually increased by prostaglandin E1 (PGE1) which maintains platelets in a disc shape and does not cause the release of granule contents, indicating that the decrease in platelet density caused by PGE1 may be attributable to platelet swelling.     

Chronic ethanol consumption alters rat liver plasma membranes and potentiates release of alkaline phosphatase

The aim of this study was to investigate possible mechanisms involved in the elevation of serum alkaline phosphatase activity in alcoholics. Male Sprague-Dawley rats were pair-fed nutritionally adequate liquid diets containing ethanol as 36% of energy or an isocaloric amount of carbohydrate for 4-5 wk. Serum alkaline phosphatase activity was increased moderately but significantly. Hepatocytes isolated from ethanol-fed animals exhibited pronounced morphologic alterations of their plasma membranes by scanning electron microscopy and a reduced content of alkaline phosphatase despite an increase in total liver alkaline phosphatase content. Chronic ethanol feeding also potentiated the release of alkaline phosphatase from the cells during incubation with 50 mM ethanol. Furthermore, chronic ethanol feeding resulted in reduced recovery of alkaline phosphatase in hepatic plasma membranes isolated by sucrose gradient centrifugation but did not affect the recoveries of other plasma membrane markers (5'-nucleotidase and Na+,K+-adenosine triphosphatase) nor the subcellular distribution of alkaline phosphatase in the nuclear, mitochondrial, microsomal, and cytosolic fractions. These findings suggest that the increased serum alkaline phosphatase levels observed in response to chronic ethanol feeding may be due, at least in part, to increased lability of this plasma membrane enzyme.     

ESIN in Forearm Fractures

Abstract Background and Purpose: Elastic stable intramedullary nailing (ESIN) is well established for stabilizing pediatric forearm fractures. To prevent uncritical use, it is necessary to evaluate the problems and complications of this common technique. Patients and Methods: Four pediatric surgical departments participated in a retrospective study analyzing the last 400 fractures treated with ESIN. Continuous documentation of treatment, postoperative course and follow-up formed the basis of evaluation. In this article forearm fractures (n = 163, 40.7%) are discussed, and epidemiology, indication, fracture types, intraoperative technique, postoperative management and problems, as well as complications and results are compared to those described in the literature. Results: Complete, transverse fractures of the midshaft (73%) were mainly seen. Indication for intervention was an intolerable axial deviation (85.9%). Intraoperative technique (operating and transillumination time, site of approach, material choice) and postoperative management (hospital stay, number of X-ray controls, and follow-up) differed highly depending on the hospitals circumstances. Postoperatively, 3.0% of patients showed soft-tissue irritation due to sharp nail ends or wound infections. Complications (10.4%) included secondary rupture of a tendon in 3.7%, refracture with nails in situ in 2.5%, axial deviations > 10° or instability of osteosynthesis in 1.8%, delayed healing in 1.2%, migration of nails in 0.6%, and technical failure in 0.6%. Overall, a significant functional restriction (limitation of movement > 10°) was found in three cases only (1.8%) following radial neck fracture. Conclusion: ESIN in pediatric forearm fractures is an often used technique with clear indications and excellent results to be expected. Numerically, complications have not altered considerably, but they rather show a shifting of problems with optimization and refinement of technique and improvement of equipment. Thus, continuous evaluation of technical principles and procedural recommendations constitutes the mainstay in the prevention of problems and complications.     

Prevalence of conditions potentially associated with lower urinary tract symptoms in men

OBJECTIVE: To estimate the frequency of conditions associated with lower urinary tract symptoms (LUTS, typically included when assessing benign prostatic hyperplasia, BPH), as other causes of LUTS should be excluded when diagnosing BPH, using data from the Olmsted County Study of Urinary Symptoms and Health Status among Men. SUBJECTS AND METHODS: During 1989-91, Caucasian men aged 40-79 years were randomly selected from the Olmsted County population. Before contact, eligibility was determined by reviewing the community medical records. Baseline exclusion criteria included comorbid pre-existing conditions or treatments, e.g. prostate, bladder or lower back surgery, bladder neck contracture or cancer, diabetes with lower extremity amputation, and neurological diseases, including Parkinson's disease, amyotrophic lateral sclerosis, multiple sclerosis, tabes dorsalis and stroke. Men with these conditions were excluded from the Olmsted County Study at baseline, because these conditions are potentially associated with LUTS. RESULTS: Of the 5100 randomly sampled men, 13.4% met at least one of the pre-existing exclusion criteria. Individually, the frequency of exclusions was 7.8% for prostate cancer or surgery, 4.8% for back surgery, 1.3% for bladder surgery and 1.4% for neurological conditions. All other conditions represented <1.0% of the study exclusions. Older men were more likely to meet at least one of the exclusion criteria, with men in their fifth to eighth decade having a total exclusion frequency of 1.4%, 5.4%, 8.5% and 32.8%, respectively. The most common reason for men in their fifth decade to be excluded was lower back surgery (0.9%), whereas the most common reason in the eighth was prostate surgery (21.8%). CONCLUSIONS: In men, conditions that may contribute to LUTS, other than BPH, are prevalent in the community and increase in frequency with age. It is important that other conditions associated with LUTS be excluded before a definitive diagnosis of BPH. Any oversight in this initial evaluation can potentially result in misclassification bias, misdiagnosis and incorrect treatment of patients.