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Biomedical subjects

K Seto

Publications and source records attributed to K Seto.

At least 181 records · Page 10Linked to original sources
PubMed1977

O-alkylhomoserine synthesis catalyzed by O-acetylhomoserine sulfhydrylase in microorganisms.

An enzyme that can synthesize O-alkylhomoserine from alcohols and O-acetylhomoserine was purified from Corynebacterium acetophilum. The enzyme was found to be identical to O-acetylhomoserine sulfhydrylase; a preparation that appeared homogeneous on polyacrylamide gel electrophoresis showed both O-alkylhomoserine-synthesizing and O-acetylhomoserine sulfhydrylase activities. Its molecular weight was determined to be about 220,000, and it consisted of two subunits. Its pH and temperature optima for the two reactions were the same. Besides catalyzing the formation of homocysteine from O-acetylhomoserine and sulfide, it also catalyzed the syntheses of O-alkylhomoserines corresponding to the alcohols added form O-acetylhomoserine and ethyl alcohol, n-propylalcohol, n-butyl alcohol, methyl alcohol, and n-pentyl alcohol, its activities with these alcohols decreasing in that order. L-Homoserine, O-succinylhomoserine, and O-acetylserine reacted with sulfide. O-ethylhomoserine, O-acetylthreonine, O-succinylhomoserine, and O-acetylserine inhibited both enzyme activities. O-acetylhomoserine sulfhydrylase purified from Saccharomyces cerevisiae also showed O-alkylhomoserine-synthesizing activity. Thus, O-acetylhomoserine sulfhydrylase seems to catalyze O-alkylhomoserine synthesis in the presence of appropriate concentrations of alcohol and O-acetylhomoserine in microorganisms.

Alcohols↗
PubMed1977

Critical review of biopsy and cytologic examination of oral cancer.

The value of cytologic diagnosis has been highly estimated since Papanicolaou introduced cytologic study into various clinical fields as a diagnostic tool. In this paper the causes of errors in diagnosis, particularly the false negative case which occurs more frequently than false positive cases are critically reviewed. Four false negative cases, including one case subsequently diagnosed as positive by a direct imprint smear taken from its biopsy section, are presented in detail and possible causative factors for misinterpretation discussed and summarized, comparing the results with those previously reported by Watanabe et al (1959) and Watanabe (1968). In the 24 cases reviewed in this article false negative diagnoses were made in 12-5 per cent and in summarizing the results with the previous reports they averaged 14-5 per cent. False negative cases could be reduced by careful attention to the elimination of the causative factors which have been described.

Adult↗
PubMed1976

In vitro transfer rate of 14C from acetate-1-14C into ovarian steroids in the rat ovary during the estrous cycle and effects of LH and FSH.

Fluctuations of ovarian biosynthetic activity and effects of exogenous LH and FSH on it during the estrous cycle were investigated by measuring in vitro transfer rates of 14C from 14C-1-acetate into progesterone (P), 20 alpha-hydroxy-pregn-4-en-3-one (20 alpha-OH-P) and estrogen (estradiol and estrone, E) in the ovarian homogenates from rats autopsied at 2 hour intervals. The transfer rate of 14C from 14C-1-acetate into P was lowest in the afternoon of estrus and increased from the morning of diestrus 1, making its peaks during the afternoon of diestrus 2 and in the midnight of proestrus. The transfer of 14C into 20 alpha-OH-P was high on the days of diestrus 2 and proestrus with its peak in the afternoon of the latter day. The maximum transfer of 14C into E in the afternoon of proestrus and a high rate in the morning of estrus with relatively low one in the midnight were observed. Exogenously injected LH (150 mug) or FSH (150 mug) was either stimulatory or inhiibitory to the transfer rates of 14C from 14C-1-acetate into ovarian steroids. During day time of diestrus 2 and midnight between proestrus and estrus, the transfer of 14C into P and 20 alpha-OH-P increased by LH, and during day time of proestrus and from the afternoon of estrus to the morning of diestrus 1 decreased. The transfer of 14C into E increased by LH from the afternoon of diestrus 2 to the morning of proestrus, and decreased during the afternoon of proestrus and from the afternoon of estrus to the morning of diestrus 2. Administration of FSH was also stimulatory or inhibitory. The 14C transfer into P and 20 alpha-OH-P increased by FSH from the afternoon of estrus to the morning of proestrus, but in the afternoon of proestrus they decreased. Transfer of 14C into E increased by FSH significantly on the days of diestrus 2 and proestrus, and slightly on the day of estrus, while it decreased in the afternoon of diestrus 1.

Acetates↗
PubMed1975

Effect of glucose load on synthesis of plasma glucose in lactating cows.

We assess the effect of an intravenous glucose load on production of glucose in lactating dairy cows. Isotope dilution techniques were utilized to measure transfer rate of plasma glucose (with tritiated glucose) and gluconeogenesis (with carbon-14 labeled propionate or carbon dioxide). A glucose load equivalent to the cow's normal transfer rate decreased endogenous glucose output two-thirds and decreased gluconeogenesis by half. Glucose concentration and transfer rate were higher within 2 h after glucose load started while carbon-14 transfer to plasma glucose became increasingly depressed and persisted for at least 1 h after loading terminated. Reduced plasma glucose synthesis from propionate during loading was associated with increased transfer of propionate carbon to plasma phospholipids, triglycerides, and cholesterol esters, and with increased plasma insulin concentration. It appears that glucogenic precursors are utilized for greater synthesis of lipid (and presumably glycogen) and that loading leads to metabolic changes causing net reduction in gluconeogenic capacity. These changes could have important implications for use of intravenous glucose in treating hypoglycemic metabolic conditions.

Animals↗