Possible enzyme deficiency in bovine lymphosarcoma cells grown in vitro

A culture of bovine lymphosarcoma cells was unable to grow in HAT medium, suggesting that the cells were unable to use either exogenous hypoxanthine or exogenous thymidine. Further work showed that they were able to incorporate tritiated thymidine but not tritiated guanine. This indicated that failure to grow in HAT medium was due to the cells being deficient in the enzyme hypoxanthine guanine phosphoribosyl transferase which is responsible for incorporation of the bases hypoxanthine and guanine. This finding may have application in the therapy of bovine lymphosarcoma.     

Oxygenation-linked subunit interactions in human hemoglobin: experimental studies on the concentration dependence of oxygenation curves

An experimental study on the concentration dependence of oxygenation curves for human hemoglobin has been carried out between 4 X 10(-8) M heme and 5 X 10(-4) M heme in 0.1 M tris(hydroxymehtyl)aminomethane hydrochloride, 0.1 M NaCl, 1 mM disodium ethylenediaminetetraacetic acid, pH 7.4, 21.5 degrees C. With decreasing hemoglobin concentration the curves show pronounced shifts in position and shape, consistent with dissociation of tetrameric hemoglobin into dimeric species of high affinity and low cooperativity. Combination of these data with independently determined values of dissociation constants for unliganded and fully liganded hemoglobin permits a resolution of the seven parameters necessary to define the linked binding and subunit association processes. The total oxygenation-linked subunit dissociation energy (6.34 kcal) was resolved into intersubunit contact energy changes between alphabeta dimers in tetrameric hemoglobin which accompany binding of the first, middle two, and last oxygen molecules. The resolution is accurate to within approximately +/-0.3 kcal. To within this limit the isolated dimers are found to bind oxygen noncooperatively and with the same affinity as isolated alpha and beta chains. Equally good fits to the data are obtained when dimers are slightly anticooperative. At least three major energetic states are apparently assumed by hemoglobin tetramers, with respect to the alpha1beta2 contact region, corresponding to (a) unliganded, (b) singly liganded, (c) triply and quadruply liganded species. The results do not establish whether these states may be assumed by a single molecule, or whether they arise as averages over a distrubution of conformational states. They do provide unequivocal evidence against a concerted transition at any particular binding step in a system with only two energetic states of tetramer (i.e., an all or none switchover between T and R states at a particular binding step).     

Comparative status of oxidative damage and antioxidant enzymes in chronic tonsillitis patients

Comparative study of two modalities i.e. antioxidant therapy (by vitamin E) and tonsillectomy was done in chronic tonsillitis patients, the study included 80 cases. It was found that both modalities were affective than tonsillectomy. Thus the use of antioxidant may be a promising alternative for the tonsillectomy.     

Sport: assessing the risk

Studies on the incidence of sports injuries are an integral part of sports medicine. A survey of three sports medicine journals showed a paucity of information in this area. In view of the need for well designed studies, a series of guidelines for studies is presented.     

Psychoautonomic and neurovascular disorders in patients with autonomic vascular dystonia and the hyperventilation syndrome and methods for their correction

35 patients with vegetocirculatory dystonia and hyperventilation syndrome, but without the signs of organic lesion of nervous system were treated. The complex treatment included the breathing exercises with feedback mechanisms, the correction of psychovegetative and neurovascular disturbances, the massage of neck region and a head, psychotherapy, angioprotective, vegeto- and psychotropic drug therapy. The disappearance of acute vascular attacks and paroxysms of migrainous headache, the normalization of all breathing parameters and the improvement of vegetative status were observed in all patients.     

Circadian responsiveness of the hypothalamic-pituitary axis

Five healthy men 25-38 years old were subjected to simultaneous composite intravenous stimulation tests of insulin hypoglycemia (0.1 U/kg), thyrotropin-releasing hormone (TRH, 100 mug), and luteinizing hormone-releasing hormone (LHRH, 50 mug) at weekly intervals to study the circadian responsiveness of the hypothalamic-adenohypophyseal axis at 0600, 1200, 1800, and 0000 hours. Blood sugar (BS), LH, follicle-stimulating hormone, TSH, prolactin, cortisol (C), growth hormone, and testosterone (T) levels were estimated before and after the administration of drugs. Comparisons were made between basal and delta values (difference between basal and peak or nadir levels) at different tests. Significant circadian variations in BS, GH, C, and, to a lesser extent PRL, responses were observed 0600 h basal and delta BS values were the lowest, delta BS was highest at 0000 h accompanied by maximal hypoglycemic symptoms; the delta values of both C and GH were significantly higher at 0600 h and 0000 h; highest mean delta PRL was observed at 0600; at 1800 h the basal plasma PRL level was maximum but the delta PRL was lowest. Plasma TSH, LH, and FSH responses did not show significant circadian variations. These results suggest that circadian variations are evident when stimuli act through central or hypothalamic mechanisms; however, direct stimulation of the adenohypophysis resulted in indentical responses at different periods tested.     

Cancer and dysplasia of the post-hysterectomy vaginal cuff

The localization of delta5-3beta-hydroxysteroid dehydrogenase activity was demonstrated histochemically in the neonatal mouse ovary. Histochemical studies were also undertaken in an attempt to investigate the effects of gonadotropic deprivation from birth to age 7 or 14 days on the distribution of enzymatic activity. Between birth and the age of 2 weeks, delta5-3beta-hydroxysteroid dehydrogenase activity was observed in virtually all follicles. In the newborn mouse ovary, the activity was found in granulosa cells of follicles developing in the center of the organ. On the 14th day, the granulosa cells of some apparently normal follicles histochemically were relatively inert, while others, obviously atretic, demonstrated extensive, localized, diformazan granules. Deprivation of endogenous circulating gonadotropin by daily injections of anti-rat gonadotropin had specific effects on follicular development and histochemical patterns in animals deprived of gonadotropins for 14 days but not for only 7 days.