Formation of glycine and aminoacetone from L-threonine by rat liver mitochondria

Threonine is a precursor of glycine in the rat, but the metabolic pathway involved is unclear. To elucidate this pathway, the biosynthesis of glycine, and of aminoacetone, from L-threonine were studied in rat liver mitochondrial preparations of differing integrities. In the absence of added cofactors, intact mitochondria formed glycine and aminoacetone in approximately equal amounts from 20 mM L-threonine, but exogenous NAD+ decreased and CoA increased the ratio of glycine to aminoacetone formed. In intact and freeze-thawed mitochondria, the ratio of glycine to aminoacetone formed was markedly sensitive to the concentration of L-threonine, glycine being the major product at low L-threonine concentrations. Disruption of mitochondrial integrity by sonication (1 min) decreased the ratio of glycine to aminoacetone formed, and in 20000 X g supernatant fractions from sonicated (3 min) mitochondria, aminoacetone was the major product. The main non-nitogenous two-carbon compound detected when intact mitochondria catabolized L-threonine to glycine was acetate, which was probably derived from deacylation of acetyl-CoA. These results suggest that glycine formation from L-threonine in rat liver mitochondria occurred primarily by the coupled activities of threonine dehydrogenase and 2-amino-3-oxobutyrate CoA-ligase, the extent of coupling between the enzymes being dependent upon a close physical relationship and upon the flux through the dehydrogenase reaction. In vivo glycine synthesis would predominate, and aminoacetone would be a minor product.     

Control in congenital adrenal hyperplasia monitored by frequent saliva 17OH-progesterone measurements

Treatment in a group of 19 patients with congenital adrenal hyperplasia (CAH) has been monitored by frequent, serial measurements of saliva 17OH-progesterone (17OHP) concentrations. Detailed 17OHP profiles were obtained during consecutive weekend days and every 1-2 h over a separate 24-hour period. Patients showed a marked diurnal rhythm in 17OHP levels, particularly when treated with hydrocortisone. In some patients, 10 mg/m2/day of hydrocortisone was sufficient glucocorticoid replacement to produce adequate control, although there was considerable individual variation. Saliva 17OHP profiles provided valuable information on the efficacy of hydrocortisone, cortisone acetate, prednisolone and dexamethasone as glucocorticoid suppressive regimes in the treatment of CAH. Preliminary results suggest that hydrocortisone given in two divided doses during the day, supplemented by a small dose of prednisolone at bedtime, is suitable treatment for CAH patients who are still growing. In the patient who has completed statural growth, single daily dose dexamethasone therapy ensures adequate adrenal suppression and is convenient in the longterm.     

Tendencies in the epidemic process of dysentery in Ryazan

In shigellosis caused by Sh. sonnei and Sh. flexneri the epidemic process was found to have considerable difference in the tendencies and pace of its development. Shigellosis which dominated in the etiological structure at the period following 1966 was dysentery caused by Sh. sonnei; it showed the tendency towards a decrease in morbidity rate. Dysentery caused by Sh. flexneri was second in respect to the frequency of its occurrence after 1966 and showed the tendency towards increase. The simultaneous circulation of Sh. sonnei and Sh. flexneri, the differences in the epidemiology of these types of shigellosis make it imperative that they be studied separately, taking into ccount their etiological selectivity to the main routes of transmitting the infection.     

Zur Frage der Natur der extremitäteninduzierenden Wirkung

Ohne Zusammenfassung     

Clastogenic effects of acrylamide in mouse bone marrow cells

Acrylamide, known to induce dominant-lethal mutations (Shelby et al., 1986; Smith et al., 1986) and heritable translocations (Shelby et al., 1987) in rodent germ cells, was hitherto a questionable clastogen in rodent bone marrow (Shiraishi, 1978). Therefore, it was tested for chromosomal aberrations in mouse bone marrow cells, spermatogonia and by the micronucleus test. The intraperitoneally injected doses ranged from 50 to 150 mg/kg. In the chromosomal bone marrow test and the micronucleus assay positive results were obtained with acrylamide, and in the latter test the effect increased linearly with dose. Chromosomal aberrations were not induced in differentiating spermatogonia by the acute acrylamide treatment. Cisplatin was used as a positive control and gave the expected positive response in all 3 tests. The present results demonstrate that acrylamide is no exception among clastogens. It breaks chromosomes not only in mammalian germ cells but also in somatic cells.     

Action of the "delta-sleep peptide" on monoamine oxidase and acetylcholinesterase activity in subcellular fractions from different rabbit brain formations in vivo

Administration of delta-sleep-inducing peptide (DSIP) in vivo in a dose of 30 microgram/kg bw brings about MAO-A (substrate-serotonin) activation in synaptosome subfractions and cellular mitochondria from the brain structures (motor cortex, nucleus caudatus, thalamus). Activity of MAO-B (substrate-p-nitrophenylethylamine) and acetylcholinesterase was inhibited negligibly and specifically in subcellular fractions of the test brain structures. The results suggest that DSIP effects the regulatory or modulation function in the synapse. As one of the elements of sleep mechanisms this peptide induces a number of processes, particularly in serotonin metabolism.     

Cryofractographic study of intercellular junctions in the populations of agar-cultivated Bordetella pertussis

The characteristic feature of replicas obtained from the freeze-fractures of B. pertussis unfixed cultures developing on casein charcoal agar for 1-7 days is the associative growth of highly polymorphic cells, ensured by the ramified system of intercellular connections (IC) formed by the derivatives of the outer layers of the cell wall. This proves that the associative location of bacterial cells, linked by numerous IC, in the preparation is not the artefact appearing in the process of their chemical fixation. In replicas obtained from the freeze-fractures of B. pertussis cultures, previously fixed with glutaraldehyde, osmic acid and uranyl acetate, oval cells with the cytoplasm having a relatively homogeneous structure and with the smoothed-out three-layer cell wall prevail. As a rule, IC are limited to the sites of direct contacts between individual cells.