The purine nucleotide cycle. Studies of ammonia production by skeletal muscle in situ and in perfused preparations

Ammonia production by hind limbs of rat was studied in perfused preparations during rest, exercise, and hypoxia, and while the perfusate contained epinephrine or cyanide. Ammonia production by hind limbs was also studied in situ during rest and exercise. Strong correlations were observed between ammonia, IMP, and lactate formation. Adenylosuccinate was not present in detectable amounts in resting muscle (less than 1 nmol/g dry weight) but it appeared and rose sharply in exercising muscle, and then declined during recovery. The maximum found was about 18 nmol/g dry weight. When IMP accumulation exceeded 2.8 mumol/g dry weight, the formation of adenylosuccinate diminished, presumably because of an inhibition of adenylosuccinate synthetase by excess substrate. Exercise resulted in a greatly increased output of ammonia and a decreased output of alanine and glutamine. The tissue contents of aspartate and glutamate were decreased, while that of alanine was increased. The content of malate increased 3-fold during exercise. Epinephrine, hypoxia, and cyanide each caused an increased output of ammonia at the expense of the amino acid content of the tissue. These results provide evidence for the operation of the purine nucleotide cycle in skeletal muscle under various conditions that are associated with an increased rate of glycolysis.     

Regeneration of the node of Ranvier: a light and electron microscope study

Regeneration of the node of Ranvier was investigated in the rat peroneal nerve 10-60 days after nerve crush, by light and electron microscopy. At 10 and 20 days after crush nodes of Ranvier were clearly identifiable by electron microscopy but had a relatively simple structure. At 40 days after crush however nodes were highly differentiated showing specialised features such as paranodal bulbs, nodal constriction of the axon, paranodal Schwann cell mitochondria, nodal Schwann cell microvilli, and nodal gap substance. By light microscopy some nodes were identifiable as early as 20 days after crush. At both 30 and 60 days after crush regenerated internodes were uniformly short (means of 275 micronm and 339 micronm respectively).     

Research with the Wechsler Intelligence Scales for Adults.

The past 5 years of research with the adult Wechsler scales is critically reviewed. Most investigators used the most recently developed scale, the Wechsler Adult Intelligence Scale. Topical coverage includes: comparative validity; short forms; special populations and applications; refinements and critiques; personality correlates; investigations of diagnostic value; special diagnostic groups; and scatter, patterns, and diagnosis. The 197 articles reviewed show that there is no diminution in the number of researches in the area. While the quality of the research has improved, too many investigators repeat the errors contained in earlier studies, despite the periodic publication of these critical reviews. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Analogues of capsaicin with agonist activity as novel analgesic agents; structure-activity studies. 3. The hydrophobic side-chain "C-region"

Structural variants of the hydrophobic side chain ("C region") of the capsaicin molecule have been incorporated into a series of vanillylamides and vanillylthioureas. These compounds have been tested in an in vitro assay for agonism (45Ca2+ influx into dorsal root ganglia neurones), previously shown to be predictive of analgesic activity. The results of this study have established the requirement for a hydrophobic substituent of limited size (molar refractivity, MR, < 55) in order to obtain high potency. Combination of the information gained here about the "C-region" of the capsaicin molecule with the studies described in the preceding two papers provides a rational basis for the design of compounds of increased potency.     

Spontaneous coronary artery dissection associated with oral contraceptive use

A 39-year-old woman presented with acute myocardial infarction due to spontaneous dissection of the left anterior descending artery. This was treated conservatively. She had been on combined oral contraceptive pills from the age of 22. Repeat coronary angiography 7 months later revealed spontaneous complete healing.