Pancreas divisum: thin-section CT

Twelve patients with known pancreas divisum underwent thin-section computed tomography (CT) to determine the capability of CT to depict this pancreatic anomaly. Focal pancreatic enlargement was present in five patients. Two distinct pancreatic moieties separated by a fat cleft were noted in three patients; a fourth patient had focal atrophy in the distribution of the dorsal pancreas. The two pancreatic moieties were identified at the same craniocaudal level in all four of these patients. The dorsal duct was depicted in all 12 patients, while the short ventral duct was seen in only five of the 12 patients. Failure of the ventral and dorsal pancreatic ducts to fuse was identified in all five patients in whom both ducts were seen. CT may not enable specific diagnosis of pancreas divisum in the majority of patients. If, however, distinct pancreatic moieties or unfused ductal systems are evident, the diagnosis may be confidently suggested.     

p-Methoxyamphetamine,a potent reversible inhibitor of type-A monoamine oxidase in vitro and in vivo

p-Methoxyamphetamine is over 20 times as potent as (+)-amphetamine as an inhibitor of 5-HT oxidation by monoamine oxidase in mouse brain in vitro, with a K_i value of 0·22 μM. It is highly selective towards A-type monoamine oxidase and possesses only weak activity against the B-type enzyme (Ki value about 500 μM with benzylamine as substrate and solubilized rat liver mitochondria as enzyme source). It is 10 times more active than (+)-amphetamine in protecting mouse brain monoamine oxidase from inhibition by phenelzine in vivo. o-Methoxy- and m-methoxyamphetamines inhibit monoamine oxidase both in vitro and in vivo with potencies comparable with, or less than that of (+)-amphetamine.     

IMPROVED PROCEDURE OF PURIFICATION OF INORGANIC PYROPHOSPHATASE FROM BACILLUS STEAROTHERMOPHILUS

An improved method for isolation of inorganic pyrophosphatase (EC 3.6.1.1.) from Bacillus stearothermophilus is described. The enzyme was purified to more than 90% after two chromatographic steps. A molecular weight of 140 000 daltons was estimated by density gradient centrifugation. The isoelectric point was found to be 4.0.     

Finite-time thermodynamics: Engine performance improved by optimized piston motion

The methods of finite-time thermodynamics are used to find the optimal time path of an Otto cycle with friction and heat leakage. Optimality is defined by maximization of the work per cycle; the system is constrained to operate at a fixed frequency, so the maximum power is obtained. The result is an improvement of about 10% in the effectiveness (second-law efficiency) of a conventional near-sinusoidal engine.