Biomedical subjects

Y Na

Publications and source records attributed to Y Na.

4 recordsLinked to original sources

PubMed2000

Highly Stereoselective and Efficient Hydrosilylation of Terminal Alkynes Catalyzed by

With [RuCl(2)(p-cymene)](2) as a catalyst, extremely high regio- and stereoselectivity was observed in the hydrosilylation reaction of various terminal alkynes under mild conditions to afford beta-(Z)-vinylsilanes in excellent yields. A dramatic directing effect was also observed when alkynes having a hydroxyl group at the beta position to the triple bond were employed as a substrate, and in these cases regioisomeric alpha-vinylsilanes were generated with excellent selectivity.

Journal Article↗

PubMed1999

Loss of heterozygosity in (LewisxF344)F1 rat urinary bladder tumors induced with N-butyl-N-(4-hydroxybutyl)nitrosamine followed by dimethylarsinic acid or sodium L-ascorbate.

Dimethylarsinic acid (DMA), a main metabolite of arsenicals which are carcinogenic in man, exerts tumor-promoting activity on rat urinary bladder carcinogenesis initiated with N-butyl-N-(4-hydroxybutyl)nitrosamine (BBN). Sodium L-ascorbate (Na-AsA) is also a strong tumor promoter in this animal model. In this study, we used (LewisxF344)F, rats to compare molecular alterations in urinary bladder tumors caused by BBN followed by DMA or Na-AsA. Male, 6-week-old rats were given 0.05% BBN in their drinking water for 4 weeks, and then the rats in group 1 were maintained with no further treatment for 40 weeks. The animals of groups 2 and 3 were administered 0.01% DMA in their drinking water (group 2) or 5% Na-AsA in the powder diet (group 3) after the BBN treatment. Group 4 rats were given 0.05% BBN continuously for 36 weeks. At weeks 12, 20, 36 and 44, subgroups of rats were killed. Histopathological examination revealed promoting activity for DMA and, to a greater extent, Na-AsA on urinary bladder carcinogenesis. Loss of heterozygosity (LOH), detected with the polymerase chain reaction using 36 microsatellite markers, was found to be present in 2 of 9 (22%) urinary bladder tumors after treatment with DMA and 3 of 22 (14%) induced by continuous administration with BBN. No LOH was, however, detected in urinary bladder tumors after treatment with Na-AsA. The results thus suggest that the mechanisms of action of these two promoters, DMA and Na-AsA, may differ in rat urinary bladder carcinogenesis.

Animals↗

PubMed1998

Breast-feeding initiation in New York City, 1979 to 1996.

OBJECTIVES: The purpose of this study was to explore changes in breast-feeding initiation from 1979 to 1996 among infants born in New York City hospitals. METHODS: All New York City hospitals were surveyed every 2 years. Hospital staff reported feeding method at newborn discharge. RESULTS: New York City breast-feeding initiation rates increased consistently from 1979 to 1996 (from 29% to 58%, P < .0001), including 1984 to 1990, when rates decreased nationally. CONCLUSIONS: A 1984 New York State regulation requiring each hospital to designate a lactation coordinator may have been associated with the continuing increases in breast-feeding initiation.

Breast Feeding↗

PubMed1998

Decrease in infant mortality in New York City after 1989.

OBJECTIVES: This study identified factors contributing to the rapid decline in infant mortality in New York City from 1989 to 1992. METHODS: Changes in birthweight distributions and in birthweight/age-, cause-, and birthweight/age/cause-specific mortality rates from 1988/89 (before the mortality reduction) to 1990/91 were identified from New York City vital statistics data. RESULTS: Infant, neonatal, and postneonatal mortality of very-low-birthweight (< 1500 g) and normal-birthweight infants decreased significantly. The declines were almost entirely due to decreases in birthweight-specific mortality rates, rather than increased birthweights. All races experienced most of these reductions. Mortality decreased significantly for 6 causes of death. These decreases were consistent with the birthweight/age groups experiencing mortality declines. CONCLUSIONS: Widespread, multiple perinatal and postnatal factors contributed to the decline in infant mortality.

Birth Weight↗