Homology modelling of two subtilisin-like proteases from the hyperthermophilic archaea Pyrococcus furiosus and Thermococcus stetteri

The hyperthermophilic archaeon Pyrococcus furiosus produces an extracellular, glycosylated hyperthermostable subtilisin-like serine protease, termed pyrolysin (Voorhorst,W.G.B., Eggen,R.I.L., Geerling,A.C.M., Platteeuw,C., Siezen,R.J. and de Vos,W.M. (1996) J. Biol. Chem., 271, 20426-20431). Based on the pyrolysin coding sequence, a pyrolysin-like gene fragment was cloned and characterized from the extreme thermophilic archaeon Thermococcus stetteri. Like pyrolysin, the deduced sequence of this serine protease, designated stetterlysin, contains a catalytic domain with high homology with other subtilases, allowing homology modelling starting from known crystal structures. Comparison of the predicted three-dimensional models of the catalytic domain of stetterlysin and pyrolysin with the crystal structure of subtilases from mesophilic and thermophilic origin, i.e. subtilisin BPN' and thermitase, and the homology model of subtilisin S41 from psychrophilic origin, led to the identification of features that could be related to protein stabilization. Higher thermostability was found to be correlated with an increased number of residues involved in pairs and networks of charge-charge and aromatic-aromatic interactions. These highly thermostable proteases have several extra surface loops and inserts with a relatively high frequency of aromatic residues and Asn residues. The latter are often present in putative N-glycosylation sites. Results from modelling of known substrates in the substrate- binding region support the broad substrate range and the autocatalytic activation previously suggested for pyrolysin.      

Effect of essential fatty acid deficiency on myelin proteins

The effect of essential fatty acid (EFA) deficiency on rat-brain myelin proteins was studied. Rats were maintained on a lipid-free diet and compared with control rats fed the same diet supplemented with 3% corn oil. At 17 days of age, each pup was injected with [³H]leucine and rats from each group were killed over a period of 163 days. Although a large decrease occurred in the total amount of myelin protein per brain, the proportions of constituent myelin proteins remained relatively unchanged. Metabolic studies showed a decrease in the net turnover of myelin proteins analogous to that previously demonstrated for myelin phospholipid (PL).     

The general practitioner as sports physician

General practitioners must become more knowledgeable about sports medicine in order both to treat the injured athlete and to provide better rehabilitative treatment and advice on fitness and exercise to other patients. Close involvement with young amateur athletes also helps to keep the older physician "in tune" with the younger generation. Finances remain a major problem for amateur sporting events and sports medicine groups, as well as for the individual physician volunteering his time.     

Quantitative determination of spleen added to ground beef

Simultaneous measurement of cardiac output distribution with 86Rubidium and 57Cobalt-tagged microspheres in rats implanted with liver tumors by intraportal injection of sarcoma cells enables quantitation of arterial and portal tumor circulation. The portal circulation was found to be increased in small tumors as compared to the liver, but as the tumor grew there was a decrease in the portal tumor circulation. When the tumor growth became massive even the total liver circulation was reduced, as measured with 133Xenon wash-out. All the tumors had increased arterial circulation. This arterial hyperperfusion was changed into ischemia when the liver artery was occluded through embolization with degradable microspheres.     

Effect of age and sex on the prevalence of intestinal parasitism in dogs

The effects of age, sex, and neutering on the prevalence of canine intestinal parasitism were evaluated by fecal examination of 1,468 pet dogs admitted to the University of Missouri Veterinary Teaching Hospital during 1975. Evidence of hookworm infection was encountered in 35.8% of the dogs examined, whipworms in 18.5%, ascarids in 17.9%, tapeworms in 5.2%, and coccidia in 4.5%. Evidence of intestinal parasitism was not detected in 653 (44.4%) dogs. Whipworm infections were detected less often in young dogs than in older ones, whereas ascarid and coccidial infections were more prevalent in pups that in mature dogs. In dogs more than 6 months old, hookworm infections were the most common parasitism. Tapeworm infections were diagnosed sporadically in all age groups. For most of these parasites, castrated males and spayed females had decreased prevalence of infection, compared with their respective intact counterparts. There were significant (P less than 0.05) differences in the prevalence of both ascarid and hookworm infections between intact and spayed female dogs. Also, there were significant (P less than 0.001) differences between age categories for all parasites observed. Overall, parasitism tended to decrease with age.     

Specificity of amphetamine induced release of norepinephrine and serotonin from rat brain in vitro

Incubation of normal rat cortical or brain stem tissue with 3H-NE or 3H-5-HT and subsequent exposure to amphetamine produced a concentration-related release of the transmitters from tissue stores into the incubation media. Although pretreatment with the catecholamine neurotoxin in 6-hydroxydopamine (6-OHDA) reduced the retention of 3H-NE in both of these tissues, the proportion of 3H-NE released by amphetamine was attenuated only in cortical tissue. Pretreatment with the serotonergic neurotoxin, 5,6-dihydroxytryptamine (5,6-DHT) had no effect on the retention or release of 3H-NE in cortical or brain stem tissue. Pretreatment with 5,6-DHT reduced the retention of 3H-5-HT in the cortex and brain stem, but the release of 3H-5-HT was significantly attenuated only in the latter tissue. 6-OHDA pretreatment increased the retention and proportion of cortical 3H-5-HT released by amphetamine but reduced the release of brain stem 3H-5-HT in the absence of an effect on retention. It appears that the in vitro release of 3H-NE from the cerebral cortex occurs primarily from catecholamine and not serotonergic neurons whereas the cortical release of 3H-5-HT is not an event specific to serotonergic nerve terminals. The release of 3H-5-HT from brain stem does not appear to be restricted to the serotonergic cell bodies since its release was attenuated by 5,6-DHT and 6-OHDA.     

Cryosurgery of bronchopulmonary structures. An approach to lesions inaccessible to the rigid bronchoscope

Cryonecrosis of the upper lobe of the lung and bronchi was safely inudced in healthy dogs by application of the cryoprobe to serosal surfaces or, through a bronchotomy, to the mucosal surfaces under direct vision. Seven days after cryosurgery, hyperemia of the bronchus was seen. By 14 days the bronchus at the target site was covered with cuboidal epithelium. Reappearance of normal ciliated epithelium occurred by 180 days after cryosurgery. Cartilage remained intact, and there was no evidence of formation of a stricture or other gross alteration of bronchial architecture. In the lung there was coagulation necrosis; and by 14 days after cryosurgery, there was fibrosis in the target area. There were no complications of the pleural space. Cryosurgery of tissues at the margins of the bronchotomy does not impair healing. Cryosurgery may reduce the necessity for extensive surgery in selected patients with bronchopulmonary tumors, including those inaccessible to the rigid bronchoscope. Clinically, eight patients with recurrent bronchogenic tumors have received palliation by transbronchoscopic cryosurgery.     

Family structure and the mental health of children. Concurrent and longitudinal community-wide studies

This study provides a map of variations of families and some of the core relationships between types of family and the mental health of children. Family types in a poor, black urban community were defined in terms of the adults present at home. The resulting taxonomy is based on two populations: half of the community's 1964 first-grade children and families and the entire 1966 first-grade children and families. Eighty-six family types were found, falling into ten major classes. Family type was found to be strongly related over time to the child's social adaptational status (SAS) and his or her psychological well-being. The results suggest that (1) mother alone families entail the highest risk in terms of social maladaptation and psychological well-being of the child; (2) the presence of certain second adults has important ameliorative functions--mother/grandmother families being nearly as effective as mother/father families, with mother/stepfather families similar to mother alone in regard to risk; and (3) the absence of the father was less important than the aloneness of the mother in relation to risk.