The process of the socialization of first year medical students is analyzed according to a paradigm of adult socialization. This paradigm consists of three sets of variables, that is, independent variable (I), personal background characteristics, independent variable (II), elements of interpersonal relation in which students are involved, and dependent variable, the cultural content of socialization. The study shows (a) that during the first year the medical students tend to think of the first year as the least important period for their later career. Besides being least important, the first year appears to be the most difficult. They also feel hard pressed for time-- there seems to be too much to learn for the time allowed. However, they expect that as they go through medical school, their training will be less difficult. A majority of them find themselves very much involved in the competition among themselves. Their attitudes towards this are rather neutral. They express satisfaction with their faculty members in the given direction in their studies. (b) In the assessment of their performance during their training, a majority of the students classify themselves as average, the reference point of which is largely found in themselves rather than in their fellow students, or in the opinion of the faculty members. (c) With regard to their attitudes and values; students tend to hold the initial values which they had on entering medical school, namely, "people-orientation." No student thinks of himself as a doctor in The first year, in fact, from the beginning he did not expect to establish his professional self-image in the first year. On the other hand, the outline of the image of physician which emerged on entry into medical school remains almost the same at the end of the year with only a slight modification. The image is characterized primarily by personality traits, and a task-oriented emphasis. As the year comes to an end, a substantial proportion of students tend to specify themselves as preferring general practice as their later career. This was not chosen by anyone at the beginning of the year. Their expected income differs little from the actual current income of physicians. They tend to express more satisfaction with their chosen career as they progress through the first year. / Arts, Faculty of / Sociology, Department of / Graduate

In recent years, two mechanisms have been proposed for the enzymatic formation of acetoacetate by liver extracts. One of these, the "HMG-CoA cycle", involves the condensation of acetyl-CoA and acetoacetyl-CoA to form β-hydroxy- β-methylglutaryl-CoA (HMG-CoA) via the action of the HMG-CoA condensing enzyme, with the release of free coenzyme A (CoASH) (reaction 1). Acetyl-CoA + acetoacetyI-CoA + H₂O⇆ HMG-CoA + CoASH (1) followed by cleavage of the HMG-CoA to acetyl-CoA and free acetoacetate, via the action of the HMG-CoA cleavage enzyme (reaction 2). HMG-CoA⇆ acetoacetate + acetyl-CoA (2) The second mechanism which has been proposed involves a direct deacylation of acetoacetyl CoA through the action of a specific acetoacetyl-CoA thioesterase (reaction). Acetoacetyl-CoA + H₂O→ acetoacetate + CoASH (3) Evidence is presented which indicates acetoacetate formation by a soluble enzyme system from bicarbonate extracts of whole beef liver proceeds largely, if not exclusively, via HMG-CoA (reactions 1 and 2). Both the HMG-CoA condensing and cleavage enzymes have been partially purified from beef liver bicarbonate extracts, each free of contamination by the other, in good yields. The level of activity of these two enzymes is sufficiently high to account for all the acetoacetate formed by liver tissue. The possibility that the specific acetoacetyl-CoA thioesterase may play a minor role in the enzymatic synthesis of acetoacetate is also discussed. The intracellular and tissue localization of the enzymes of acetoacetate formation is also discussed. In liver homogenates, most, if not all, of the acetoacetate-synthesizing activity appears to be associated with the mitochondrion. Evidence is also presented that the primary reason for the inability of extrahepatic tissue preparations to catalyze the accumulation of acetoacetate may be the lack of one of the enzymes involved, i.e., the HMG-CoA condensing enzyme, and not merely further metabolic degradation of acetoacetate, as has generally been assumed. An enzyme fraction in chicken liver extracts which inhibits the in vitro formation of acetoacetate by chicken liver homogenates has also been studied. Evidence is presented that this enzyme fraction exerts its effect through the inactivation of coenzyme A. Preliminary observations indicate that this enzyme may be a 3’-nucleotidase, removing the 3’- phosphate of coenzyme A, forming dephosphocoenzyme A. The occurrence of a highly active β-hydroxybutyryl dehydrogenase in extracts of dry culture of C. kluyveri has been noted. This enzyme differs from the similar enzyme reported in mammalian tissues, in that it is very specific for triphosphopyridine nucleotide, and is virtually inactive with diphosphopyridine nucleotide (DPN) (reaction). Acetoacetyl-CoA + TPNH + H⁺⇆β - hydroxybutyryl-CoA (4) + TPN⁺ / Medicine, Faculty of / Anesthesiology, Pharmacology and Therapeutics, Department of / Graduate

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Many bacteria accumulate carbon stores as poly-3-hydroxybutyrate (PHB) when growth is limited but carbon availability is not. This stored carbon can then be utilized during conditions of limited carbon availability. The net PHB accumulation in the cell is dependent on the balance between PHB synthesis and degradation. Sinorhizobium meliloti accumulates PHB in the free-living stage but not in the symbiotic stage. The physiological role of the PHB cycle in S. meliloti is unknown. As a first step to understand the genetics of PHB degradation, transposon-generated mutants that were not able to use PHB degradation intermediates, such as 3-hydroxybutyrate and acetoacetate, as a sole carbon source, were isolated. Genetic mapping revealed that there were at least three chromosomal loci involved in acetoacetate metabolism. Identification of these three loci determined that in S. meliloti: (1) acetoacetyl-CoA synthetase (AcsA), encoded by acsA2 gene, rather than the enzyme acetoacetate:succinyl-CoA transferase, is the enzyme that catalyzes activation of acetoacetate to acetoacetyl-CoA; (2) PHB synthase, encoded by phbC, is required for acetoacetate utilization; (3) a putative transporter protein encoding gene, aau-3, may also be involved in acetoacetate metabolism. acsA2 and aau-3 were 78% linked in co-transduction, while phbC was mapped to somewhere else on the chromosome. Biochemical analysis revealed that acsA2::Tn5 mutants lacked AcsA activity but not acetoacetate:succinyl-CoA transferase activity, while phbC::Tn5 maintained similar level of AcsA activity as wild type in vitro. PHB was absent in the phbC mutant. / One transposon-generated mutant, age-1, showed enhanced growth rate on acetoacetate medium. Genetic mapping and transductional analysis indicated that the location of the mutation in age-1 is tightly linked to acsA2. Fine mapping with PCR and DNA sequence techniques showed that Tn5 in age-1 was located at 132 by upstream of the putative translation start site of acsA2. Gene expression analysis indicated that age-1 insertion results in elevated transcription of acsA2. Thus enhanced growth rate on acetoacetate was due to the increased gene expression. acsA2 transcription was induced by acetoacetate and 3-hydroxybutyrate, and repressed by glucose and acetate. / All mutants formed root nodules that fixed nitrogen with varying decrease of impairment. Acetoacetate metabolism and the PHB degradation are not essential for symbiosis.