Abnormal adaptation of visual contrast sensitivity in multiple sclerosis patients.

Some multiple sclerosis patients with 20/20 acuity complain of poor vision. In a previous report we accounted for this in our patient group by showing that multiple sclerosis had caused a depression of contrast sensitivity while sparing visual acuity. In this study we investigated whether some of this measured depression might be due to abnormally rapid or severe adaptation during the test procedure rather than a true permanent loss.

Application of arabinofuranosyl cytosine in the kinetic analysis and quantitation of DNA repair in human cells after ultraviolet irradiation.

We have developed a technique whereby 3-h pulses of arabinofuranosyl cytosine (ara-C) and hydroxyurea (HU) are used to analyze the kinetics of repair with time after ultraviolet irradiation in human fibroblasts. We demonstrate that this technique offers a significant improvement over existing repair assays in its ability to visualize between 57 and 100% of all sites undergoing repair in a given period of time. In addition, kinetic analyses of repair are more easily made and yield more information than techniques such as repair replication or unscheduled DNA synthesis.

Correlations between visual test results and flying performance on the advanced simulator for pilot training (ASPT).

Looking for visual differences in pilots to account for differences in flying performance, we tested five groups of subjects: Air Force primary student jet pilots, graduating (T38 aircraft) students, Air Force pilot instructors, and two control groups made up of experienced nonpilot aircrew and nonflying civilians. This interim report compares 13 different visual test results with low-visibility landing performance on the Air Force Human Resources Laboratory ASPT simulator. Performance was assessed by the number of crashes and by the distance of the aircraft from the runway threshold at the time of the first visual flight correction.

Quantitative estimation of the extent of alkylation of DNA following treatment of mammalian cells with non-radioactive alkylating agents.

Alkaline sucrose sedimentation has been used to quantitate phosphotriester formation following treatment of human cells with the monofunctional alkylating agents methyl and ethyl methanesulfonate. These persistent alkaline-labile lesions are not repaired during short-term culture conditions and thus serve as a useful and precise index of the total alkylation of the DNA. Estimates of alkylation by this procedure compare favorably with direct estimates by use of labeled alkylating agents.

Effect of sulfinpyrazone on ventricular fibrillation during acute myocardial ischemia.

In patients treated with sulfinpyrazone, an apparent reduction in the incidence of sudden death and presumed ventricular fibrillation has been reported. Using an intact animal model without microcirculatory thrombosis, we studied the effects of sulfinpyrazone on ischemic myocardium in 58 anesthetized dogs divided into three groups: control untreated (n =24), group 1 (n = 16), treated daily with 300 mg of sulfinpyrazone for 7 days, and group 2 (n = 18), treated daily with 300 mg of sulfinpyrazone for 7 days but omitting treatment on day 8. Although consistent hemodynamic differences were not apparent, the degree of injury determined by ECG mapping was significantly lower in group 1.

The relationship of DNA excision repair of ultraviolet-induced lesions to the maximum life span of mammals.

Physical and chemical agents present in the environment can potentially damage mammalian DNA. Such damage is known in some cases to be repaired by the process of DNA excision repair. This process has been extensively studied utilizing the repair of ultraviolet irradiation damage as a model system.

Depression of myocardial function during acute pancreatitis.

The left ventricular function of 24 patients with acute pancreatitis was studied noninvasively using systolic time intervals. Seven of the 24 patients were reevaluated 4-40 days following the onset of acute symptoms. During the acute phase the PEP/LVET ratio was significantly prolonged to 0.

Evaluation of thallium-201 imaging in nontransmural ischemia and infarction.

To assess the validity of thallium-201 myocardial imaging in the diagnosis of nontransmural ischemia and infarction, the proximal left anterior descending coronary artery was partially occluded for 60 minutes with a balloon-tip catheter in intact anesthetized dogs in a basal state or during atrial pacing. In vivo scintigrams of myocardium were compared with those obtained in the isolated heart and in the incised ventricle spread flat. None of the animals with partial occlusion with or without pacing demonstrated abnormal scintiscans in vivo.

Cell sodium and the induction of myocardial injury after adrenaline.

Accumulation of calcium in cardiac cells during catecholamine induced injury is considered a major pathogenetic factor but its mechanism has not been defined. During initiation of injury in an intact canine model, cell sodium was enhanced fourfold in myocardium after a local infusion of epinephrine via the left anterior descending coronary artery for a 60 min period. Tissue calcium was enhanced and a major role for the Na-Ca carrier system is suggested.

Temporal selectivity of changing-size channels.

Changing-size channels tuned to the oscillation frequency are excited by a stimulus square whose size oscillates at a fixed frequency. In the 0.25-16 Hz frequency band there are at least three kinds of changing-size channels tuned to different frequencies.

Comparison of the effects of cholecystokinin and cholecystokinin octapeptide on pancreatic secretion, gallbladder contraction, and plasma pancreatic polypeptide in man.

To assess the possible clinical utility of the C-terminal CCK-OP as a stimulus to exocrine and endocrine pancreatic secretin and gallbladder contraction in man, we administered increasing doses of CCK (0.066, 0.125, 0.

The benzodiazepine receptor of mammalian brain.

There exists a saturable, high-affinity, stereospecific, regionally and pharmacologically specific, neuronally localized benzodiazepine receptor in mammalian brain, which has a development profile similar to other neurotransmitter receptors. This receptor appears to be modulated by gamma-aminobutyric acid and selected divalent cations, and chloride ions increase the affinity of the receptor for benzodiazepines. Several benzodiazepines were shown to bind irreversibly to the receptor upon exposure to ultraviolet light and these agents can be used to facilitate solubilization and purification of the benzodiazepine receptor.

Influence of fructose on the glycogen synthase and phosphorylase systems in rat liver.

Fructose and glucose, when administered as a single, large intravenous dose (500 mg/kg) produced opposite effects on key regulatory enzymes of glycogen metabolism in intact normal fed animals. Glucose rapidly stimulated glycogen synthase phosphatase activity and increased the proportion of glycogen synthase in the active (I) form as expected; fructose reduced synthase phosphatase activity and the proportion of synthase in the I form. Glucose also stimulated a reduction in the proportion of phosphorylase in the active (a) form, whereas fructose stimulated an increase in the proportion of phosphorylase in thea form.

Duodenal calcium outputs in health and pancreatic disease.

To investigate the relationship between the duodenal outputs of calcium and diseases of the pancreas, we measured calcium secretion into the duodenum (during saline perfusion and after stimulation with an intravenous infusion of cholecystokinin (CCK) or secretin) in healthy controls, patients with chronic alcoholic or idiopathic pancreatitis, and patients with pancreatic cancer. The effects of acute and chronic hypercalcaemia and previous cholecystectomy were also studied. Our results indicate a characteristic increase in duodenal calcium outputs in response to CCK in chronic pancreatitis which is unaffected by the level of serum calcium, aetiology of the pancreatitis, previous cholecystectomy, and the presence or absence of radiological pancreatic calcifications.