Biomedical subjects
Publications and source records attributed to S K Wang.
Bioactivity-guided fractionation of a CHCl3 extract of the soft coral Lobophytum michaelae afforded a new cytotoxic cembranolide, lobomichaolide (1), and a known cytotoxic cembranolide, crassolide (2). The structure of 1 was determined by spectral and X-ray crystallographic analysis.
Nonoxynol 9 (non-9) is the active ingredient in a wide variety of vaginal contraceptive preparations. The manufacturer recommendation for optimal contraceptive practice is repeated application every 6 h. We studied the in vitro activity of non-9 against Chlamydia trachomatis (E/UW-5/Cx) and its toxicity against HeLa 229 cells and monkey cervical epithelial cells. With a contact time of 6 h, non-9 was toxic to HeLa cells at concentrations of 50 micrograms/ml or greater and to monkey cervical cells at 100 micrograms/ml or greater. Inhibitory effects of non-9 on extracellular chlamydiae were observed at concentrations of 50 micrograms/ml or greater. Inhibition of intracellular growth of chlamydiae in monkey cervical cells was observed at a nontoxic concentration of 50 micrograms/ml. Our studies show that non-9 has antichlamydial activity. However, owing to its toxicity to cervical cells in vitro, the effects of prolonged use of non-9 in vivo should be further studied.
Ascorbic acid (vitamin C) is an essential nutrient for humans. It may also be needed by Chlamydia trachomatis, an intracellular bacterium. We investigated the effects of vitamin C on the growth of C. trachomatis E/UW-5/Cx in a primary culture of human amniotic epithelial cells. The results showed that vitamin C enhances C. trachomatis infection at concentrations of 0.2, 0.6, and 1.2 mg/dl (P less than 0.001). These three concentrations represent the in vivo concentrations of deficiency, normal, and overload levels in serum, respectively. The enhancement was dose dependent. However, the growth of C. trachomatis was inhibited at vitamin C concentrations of 120 and 1,200 mg/dl. The inhibitory effect of erythromycin against C. trachomatis was shown to be reduced in the presence of vitamin C at the three concentrations tested (P less than 0.025-0.001), and MICs were four times greater (1.6 versus 0.4 micrograms/ml). Human amniotic cells were tolerant to vitamin C concentrations of up to 1,200 mg/dl. The results show that vitamin C may be an important nutrient for C. trachomatis and that incorporation of vitamin C in the culture medium may enhance the isolation and propagation of C. trachomatis in cell cultures.
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The measurement of 13 items in the face and nose of 220 young adults (110 males and 110 females) of the Han nationality between the ages of 18 and 21 years has been done in the Henan Province of China. The means and standard deviations have been obtained, and the significant differences in many items between males and females have been proved. Some items influencing outer nasal shape have been analyzed. The correlations between nose height, nose length, and morphologic facial height and physiognomic facial height have been discussed. The ratio and amount of nasal breadth to facial breadth and nasal breadth to interocular breadth have been compared and analyzed, and the differences among the different races and between the sexes have been explained.
Rats were randomly divided into 4 groups: Control, Electro-acupuncture (EA), Naloxone and Naloxone plus EA. The content of noradrenaline (NA) and dopamine (DA) in brain stem, diencephalon and telencephalon were determined by spectrofluorometry. It was found that the pain threshold increased and the NA content in the telencephalon decreased and the DA level in the brain stem increased markedly after EA. Naloxone injection partially decreased the analgesic effect of EA and abolished the EA-induced elevation of DA in the brain stem and attenuated the NA level in the diencephalon after EA. These results suggest that morphine receptor may play an important role in EA analgesia and this may be partially carried out through the brain catecholamine system.
In the present study, rats were synchronized with light from 8:00 to 20:00, then darkness. Water and food were available ad libitum. The basic levels in medulla oblongata plus pons, hypothalamus, hippocampus midbrain, striatum and cortex, and electroacupuncture influences on them were compared at four different times of a day (5:00, 11:00, 17:00 and 23:00). It was found that: (1) The basic level of LEK in the medulla oblongata plus pons at 11:00 was the highest among the four times; (2) The LEK content increased by 34.8% in the hypothalamus and decreased by 21.4% in the cortex when EA was given at 5:00; The LEK levels in the hypothalamus and the hippocampus increased by 65.3% and by 37.0% respectively when EA at 11:00. The LEK level in the hippocampus increased by 50.1% when EA at 17:00; The hippocampus decreased by 29.8% when EA at 23:00. The results show that a circadian rhythm was evident in the LEK level of the rat medulla oblongata plus pons, also EA at different hours produced different effects on LEK contents in rat discrete brain regions. This provides experimental evidence for acupuncture treatment selecting hours clinically. Also, the physiological circadian variation and the influence of time factor on acupuncture effects should be considered in study of acupuncture mechanism.
The contents of Met-enkephalin (MEK) and Leu-enkephalin (LEK) in striatum and MEK in hypothalamus of rat increased markedly after electroacupuncture analgesia (EAA). Intraperitoneal injection of phentolamine, a blocker of alpha receptor, potentiated the EAA and abolished the effects of EA increasing MEK and LEK contents; while injection of propranolol, a blocker of beta receptor, partially inhibited the EAA, as well as abolished the effects of EA increasing MEK and LEK concentrations in the striatum and the hypothalamus, and also elevated the MEK and LEK contents in hippocampus and MEK level in cortex. The results indicate that EA regulates metabolism of MEK and LEK, as well as EAA partially via alpha and beta receptors.
The basic level of methionin-enkephalin (MEK) in rat medulla oblongata plus pons was the highest at 05:00 o'clock and the lowest at 23:00. In both hypothalamus and striatum at 05:00 it was higher than at 11:00, 17:00 and 23:00. In both hippocampus and midbrain at 05:00 and 23:00 it was higher than those at 11:00 and 17:00. In the cortex it was higher at 05:00 than at 11:00 and 17:00. The basic level of leucine enkephalin (LEK) in the medulla oblongata plus pons was the highest at 11:00 and the lowest at 17:00 and 23:00. Electroacupuncture (EA) at 05:00 increased the MEK content in the medulla oblongata plus pons and the LEK level in the hypothalamus. It decreased the MEK content in the hypothalamus and the LEK level in the cortex; EA at 11:00 produced decreases of MEK concentrations in the medulla oblongata plus pons and the midbrain and increases of MEK content in the cortex, hypothalamus and striatum. At 17:00 it increased the MEK level in the hypothalamus and the LEK content in the hippocampus. At 23:00 it reduced the levels of MEK and LEK in the hippocampus. The results suggest that there are very marked circadian rhythms in the MEK basic levels of the six discrete brain regions observed and the LEK of the medulla oblongata plus pons; EA at different times produces different effects on brain MEK and LEK levels.
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Pseudomonas aeruginosa region II alginate genes are involved in the biosynthesis of the uronic acid containing exopolysaccharide, alginic acid. We have subcloned and overexpressed various DNA fragments contained within region II in an attempt to further characterize and more precisely localize the genes involved in alginate production. Overexpression of the genes controlling alginate biosynthesis within region II was accomplished by placing various cloned restriction fragments under the transcriptional control of the hybrid trp-lac (tac) promoter, and plasmid encoded proteins were examined in a maxicell expression system. We correlated various region II plasmid constructions with the ability to complement specific alginate negative (alg) mutants and code for polypeptides. Several proteins suspected of being involved in alginate production were encoded by sequences within region II. The results of this study further reveal that the transcriptional orientation of the alg loci within region II appears to be in the direction from argF to pmi. The specific activities of phosphomannomutase (PMM) and GDP-mannose pyrophosphorylase (GMP), two enzymes involved in the formation of the alginate precursor GDP-mannuronic acid, were measured in region II alg mutants and in cells overexpressing cloned segments from region II. Based on these enzyme measurements, we conclude that the remaining region II alg genes do not encode either PMM or GMP. These results support the suggestion that the remaining alg genes in region II are likely to be involved in post GDP-mannuronic acid processing events such as mannuronic acid transport, polymerization, secretion, epimerization and acetylation.
The specific activities of phosphomannose isomerase (PMI), phosphomannomutase (PMM), GDP-mannose pyrophosphorylase (GMP), and GDP-mannose dehydrogenase (GMD) were compared in a mucoid cystic fibrosis isolate of Pseudomonas aeruginosa and in two spontaneous nonmucoid revertants. In both revertants some or all of the alginate biosynthetic enzymes we examined appeared to be repressed, indicating that the loss of the mucoid phenotype may be a result of decreased formation of sugar-nucleotide precursors. The introduction and overexpression of the cloned P. aeruginosa phosphomannose isomerase (pmi) gene in both mucoid and nonmucoid strains led not only to the appearance of PMI levels in cell extracts several times higher than those present in the wild-type mucoid strain, but also in higher PMM and GMP specific activities. In extracts of both strains, however, the specific activity of GMD did not change as a result of pmi overexpression. In contrast, the introduction of the cloned Escherichia coli manA (pmi) gene in P. aeruginosa caused an increase in only PMI and PMM activities, having no effect on the level of GMP. This suggests that an increase in PMI activity alone does not induce high GMP activity in P. aeruginosa. The heterologous overexpression of the P. aeruginosa pmi gene in the E. coli manA mutant CD1 led to the appearance in cell extracts of not only PMI activity but also GMP activity, both of which are normally undetectable in extracts of CD1. We discuss the implications of these results and propose a mechanism by which overexpression of the P. aeruginosa pmi gene can cause an elevation in both PMM and GMP activities.
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We present a class of group sequential tests, indexed by a single parameter, that yields approximately optimal results. We also provide tables of key values to help in the design of group sequential tests that meet selected specifications.
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