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Biomedical subjects

T Wang

Publications and source records attributed to T Wang.

At least 145 records · Page 8Linked to original sources
PubMed2001

Effects of some water-quality and operating parameters on the decolorization of reactive dye solutions by ozone.

The ozonation of reactive dye solutions has been investigated. Results of studies on ozone mass transfer indicated that the volumetric mass transfer coefficient of ozone increased with the following water-quality and operating parameters: pH, initial dye concentration, applied ozone dose, and temperature. A model was developed to predict the volumetric mass transfer coefficient of ozone from the above parameters. The results of kinetic studies showed that ozonation of the aqueous reactive dye was a pseudo-first-order reaction with respect to the dye. The apparent rate constant increased with the pH, applied ozone dose and temperature, however, it declined logarithmically with the initial dye concentration. Meanwhile, Ozonation enhanced the biodegradability and reduced the COD of the reactive dye wastewater effectively.

Biodegradation, Environmental↗
PubMed2001

Effects of N-nitropyrazoles on ocular blood flow of rabbits and retinal function recovery of rat eyes after ischemic insults.

Twelve compounds of N-nitropyrazoles were studied for their effects on ocular blood flow in rabbits and retinal function recovery in rat eyes after ischemic insults. Of the twelve N-nitropyrazoles examined, nine increased choroidal blood flow while five increased retinal blood flow significantly. On the other hand, all twelve compounds increased blood flow in iris and ciliary muscle without exception. As for retinal function recovery after ischemic insult in rat eyes, eight out of the twelve compounds showed more significant facilitation than the control. The structure activity relationship of the N-nitropyrazoles to increase ocular blood flow and to facilitate retinal function recovery after ischemic insults were discussed.

Animals↗
PubMed2001

Red and black rice decrease atherosclerotic plaque formation and increase antioxidant status in rabbits.

The influence of white, red and black rice consumption on atherosclerotic plaque formation induced by hypercholesterolemia was investigated in rabbits. Male rabbits (n = 36) were divided into five groups. They were fed a normal laboratory purified diet (normal group, n = 6), a high cholesterol (0.5 g/100 g) diet (HC group, n = 6), a high cholesterol diet with 30 g/100 g white rice (WR group, n = 8), 30 g/100 g red rice (RR group, n = 8), or 30 g/100 g black rice (BR group, n = 8) for 10 wk. Blood samples were collected for lipid measurements and aorta were removed for assessment of atherosclerotic plaques at the end of the protocol. The oxidant and antioxidant status of blood, erythrocytes, liver and aorta was evaluated. The area of atherosclerotic plaque was 50% lower in rabbits fed the red or black rice diets than in those fed the white rice diet. Compared with the HC and WR groups, serum HDL cholesterol and apolipoprotein (apo) A-I concentration were greater (P < 0.05) in the RR and BR groups. Liver reactive oxygen species (ROS) and aortic malondialdehyde (MDA) were significantly lower, and the liver total antioxidative capacity (TAC) and erythrocyte superoxide dismutase (SOD) activity were significantly higher in the RR and BR groups compared with the HC and WR groups. Red or black rice consumption reduced or retarded the progression of atherosclerotic plaque development induced by dietary cholesterol. The enhanced serum HDL cholesterol and apo A-I concentrations, and the increased antioxidant and decreased oxidative status may be mechanisms of the antiatherogenic effect of red or black rice.

Analysis of Variance↗
PubMed2001

Risk factor distribution among sociodemographically diverse African American adults.

Because African Americans tend to have lower socioeconomic status (SES) than whites and numerous health indicators are related to SES variables, it is important when examining between-group differences in health indices to account for SES differences. This study examined the effects of income and education on several biologic and behavioral risk factors in a sample of sociodemographically diverse African American adults. Approximately 1,000 African American adults (aged 18-87) were recruited from 14 churches with predominantly black membership to participate in a nutrition education intervention. Demographics, height, weight, blood pressure, self-reported cigarette and alcohol use, self-reported diet by food frequency questionnaire, serum carotenoids, serum total cholesterol, and nutrition knowledge were assessed. The association of these risk factors were examined by four levels of education and income. For men, body mass index, blood pressure, total cholesterol, daily intake of fruits and vegetables, serum carotenoids, heavy alcohol use, or exercise were not associated significantly with income or education using analysis of variance (ANOVA). Past month alcohol use and nutrition knowledge were associated positively with education, but not income. For women, body mass index and smoking were associated inversely with income, but not with education. Blood pressure, total cholesterol, intake of fruits and vegetables, heavy alcohol use, and exercise were not associated with either income or education using ANOVA. Serum carotenoids, any 30-day alcohol use, and nutrition knowledge were associated positively with both income and education. Results using linear regression generally were similar for men and women, although a few more variables were associated significantly with SES compared to ANOVA analyses. Several health indicators that have been associated with socioeconomic variables in whites were not associated or only weakly associated in this diverse sample of African Americans. One interpretation of these findings is that SES factors may function differently among blacks and whites.

Adolescent↗
PubMed2001

Mink cell focus-forming murine leukemia virus killing of mink cells involves apoptosis and superinfection.

Induction of apoptosis by different types of pathogenic retroviruses is an important step in disease development. We have observed that infection of thymic lymphocytes by the mink cell focus-forming murine leukemia virus (MCF MLV) during the preleukemic period resulted in an enhancement of apoptosis of these cells. To further study the ability of MCF MLVs to induce apoptosis and the role of this process in viral pathogenesis, we have developed an in vitro system of virus-induced apoptosis. MCF13 MLV infection of mink epithelial cells resulted in the production of cytopathic foci. In contrast, infection of mink cells with the 4070A amphotropic MLV did not produce any cytopathic effects. Staining of MCF13 MLV-infected cells with propidium iodide and annexin V-fluorescein isothiocyanate indicated that virus-induced cell death was due to apoptosis. At 6 days postinfection, the percentage of apoptotic MCF13 MLV-infected cells was 27% compared with 2 to 3% for mock- or amphotropic MLV-infected cells, representing a 9- to 14-fold difference. Assays for caspase-3 activation confirmed the detection by flow cytometry of apoptosis of MCF13 MLV-infected cells. Large amounts of unintegrated linear viral DNA were detectable by Southern blot analysis during the acute phase of infection, which indicated that MCF13 MLV is able to superinfect mink cells. Unintegrated viral DNA of only the linear form was detectable in thymic lymphocytes isolated from MCF13 MLV-inoculated mice during the preleukemic period. These results indicated that the ability of MCF13 MLV to induce apoptosis is correlated with its ability to superinfect cells and that this occurs as an early step in thymic lymphoma development.

Animals↗
PubMed2001

The gastrins: their production and biological activities.

Gastric epithelial organization and function are controlled and maintained by a variety of endocrine and paracrine mediators. Peptides encoded by the gastrin gene are an important part of this system because targeted deletion of the gene, or of the gastrin-CCKB receptor gene, leads to decreased numbers of parietal cells and decreased gastric acid secretion. Recent studies indicate that the gastrin precursor, preprogastrin, gives rise to a variety of products, each with a distinctive spectrum of biological activity. The conversion of progastrin to smaller peptides is regulated by multiple mechanisms including prohormone phosphorylation and secretory vesicle pH. Progastrin itself stimulates colonic epithelial proliferation; biosynthetic intermediates (Gly-gastrins) stimulate colonic epithelial proliferation and gastric epithelial differentiation; and C-terminally amidated gastrins stimulate colonic proliferation, gastric epithelial proliferation and differentiation, and acid secretion. The effects of progastrin-derived peptides on gastric epithelial function are mediated in part by release of paracrine factors that include histamine, epidermal growth factor (EGF)-receptor ligands, and Reg. The importance of the appropriate regulation of this system is shown by the observation that prolonged moderate hypergastrinemia in transgenic mice leads to remodelling of the gastric epithelium, and in the presence of Helicobacter, to gastric cancer.

Animals↗
PubMed2001

Essential role of NHE3 in facilitating formate-dependent NaCl absorption in the proximal tubule.

The absorption of NaCl in the proximal tubule is markedly stimulated by formate. This stimulation of NaCl transport is consistent with a cell model involving Cl(-)-formate exchange in parallel with pH-coupled formate recycling due to nonionic diffusion of formic acid or H(+)-formate cotransport. The formate recycling process requires H(+) secretion. Although Na(+)-H(+) exchanger isoform NHE3 accounts for the largest component of H(+) secretion in the proximal tubule, 40-50% of the rates of HCO absorption or cellular H(+) extrusion persist in NHE3 null mice. The purpose of the present investigation is to use NHE3 null mice to directly test the role of apical membrane NHE3 in mediating NaCl absorption stimulated by formate. We demonstrate that formate stimulates NaCl absorption in the mouse proximal tubule microperfused in vivo, but the component of NaCl absorption stimulated by formate is absent in NHE3 null mice. In contrast, stimulation of NaCl absorption by oxalate is preserved in NHE3 null mice, indicating that oxalate-stimulated NaCl absorption is independent of Na(+)-H(+) exchange. The virtually complete dependence of formate-induced NaCl absorption on NHE3 activity raises the possibility that NHE3 and the formate transporters are functionally coupled in the brush border membrane.

Absorption↗
PubMed2001

Role of NHE isoforms in mediating bicarbonate reabsorption along the nephron.

This study assessed the functional role of Na(+)/H(+) exchanger (NHE) isoforms NHE3 and NHE2 in the proximal tubule, loop of Henle, and distal convoluted tubule of the rat kidney by comparing sensitivity of transport to inhibition by Hoe-694 (an agent known to inhibit NHE2 but not NHE3) and S-3226 (an agent with much higher affinity for NHE3 than NHE2). Rates of transport of fluid (J(v)) and HCO(3)(-) (J(HCO3)) were studied by in situ microperfusion. In the proximal tubule, addition of ethylisopropylamiloride or S-3226 significantly reduced J(v) and J(HCO3), but addition of Hoe-694 caused no significant inhibition. In the loop of Henle, J(HCO3) was also inhibited by S-3226 and not by Hoe-694, although much higher concentrations of S-3226 were required than what was necessary to inhibit transport in the proximal tubule. In contrast, in the distal convoluted tubule, J(HCO3) was inhibited by Hoe-694 but not by S-3226. These results are consistent with the conclusion that NHE2 rather than NHE3 is the predominant isoform responsible for apical membrane Na(+)/H(+) exchange in the distal convoluted tubule, whereas NHE3 is the predominant apical isoform in the proximal tubule and possibly also in the loop of Henle.

Absorption↗
PubMed2001

Haplotype analysis of BRCA2 8765delAG mutation carriers in French Canadian and Yemenite Jewish hereditary breast cancer families.

The BRCA2 8765delAG mutation was previously reported in hereditary breast cancer families of French Canadian and Yemenite Jewish descent. Haplotype analysis, using six microsatellite markers that span BRCA2 and two intragenic polymorphisms, was performed on 8765delAG mutation carriers to determine if there was evidence that the mutations were identical by descent. The alleles of the microsatellite markers most closely flanking BRCA2 (D13S1697 and D13S1701) were found to be identical in state in all the mutation carriers. However, the disease-associated allele of one of the intragenic markers differed between the Yemenite Jews and French Canadian families, indicating that the 8765delAG mutation has independent origins in these two geographically and ethnically distinct populations.

BRCA2 Protein↗
PubMed2001

Acute and chronic influence of temperature on red blood cell anion exchange.

Unidirectional (36)Cl(-) efflux via the red blood cell anion exchanger was measured under Cl(-) self-exchange conditions (i.e. no net flow of anions) in rainbow trout Oncorhynchus mykiss and red-eared freshwater turtle Trachemys scripta to examine the effects of acute temperature changes and acclimation temperature on this process. We also evaluated the possible adaptation of anion exchange to different temperature regimes by including our previously published data on other animals. An acute temperature increase caused a significant increase in the rate constant (k) for unidirectional Cl(-) efflux in rainbow trout and freshwater turtle. After 3 weeks of temperature acclimation, 5 degrees C-acclimated rainbow trout showed only marginally higher Cl(-) transport rates than 15 degrees C-acclimated trout when compared at the same temperature. Apparent activation energies for red blood cell Cl(-) exchange in trout and turtle were lower than values reported in endothermic animals. The Q(10) for red blood cell anion exchange was 2.0 in trout and 2.3 in turtle, values close to those for CO(2) excretion, suggesting that, in ectothermic animals, the temperature sensitivity of band-3-mediated anion exchange matches the temperature sensitivity of CO(2) transport (where red blood cell Cl(-)/HCO(3)(-) exchange is a rate-limiting step). In endotherms, such as man and chicken, Q(10) values for red blood cell anion exchange are considerably higher but are no obstacle to CO(2) transport, because body temperature is normally kept constant at values at which anion exchange rates are high. When compared at constant temperature, red blood cell Cl(-) permeability shows large differences among species (trout, carp, eel, cod, turtle, alligator, chicken and man). Cl(-) permeabilities are, however, remarkable similar when compared at preferred body temperatures, suggesting an appropriate evolutionary adaptation of red blood cell anion exchange function to the different thermal niches occupied by animals.

Animals↗
PubMed2001

Autonomic control of heart rate during forced activity and digestion in the snake Boa constrictor.

Reptiles, particularly snakes, exhibit large and quantitatively similar increments in metabolic rate during muscular exercise and following a meal, when they are apparently inactive. The cardiovascular responses are similar during these two states, but the underlying autonomic control of the heart remains unknown. We describe both adrenergic and cholinergic tonus on the heart during rest, during enforced activity and during digestion (24-36 h after ingestion of 30 % of their body mass) in the snake Boa constrictor. The snakes were equipped with an arterial catheter for measurements of blood pressure and heart rate, and autonomic tonus was determined following infusion of the beta-adrenergic antagonist propranolol (3 mg kg(-1)) and the muscarinic cholinoceptor antagonist atropine (3 mg kg(-1)). The mean heart rate of fasting animals at rest was 26.4+/-1.4 min(-1), and this increased to 36.1+/-1.4 min(-1) (means +/- S.E.M.; N=8) following double autonomic block (atropine and propranolol). The calculated cholinergic and adrenergic tones were 60.1+/-9.3 % and 19.8+/-2.2 %, respectively. Heart rate increased to 61.4+/-1.5 min(-1) during enforced activity, and this response was significantly reduced by propranolol (maximum values of 35.8+/-1.6 min(-1)), but unaffected by atropine. The cholinergic and adrenergic tones were 2.6+/-2.2 and 41.3+/-1.9 % during activity, respectively. Double autonomic block virtually abolished tachycardia associated with enforced activity (heart rate increased significantly from 36.1+/-1.4 to 37.6+/-1.3 min(-1)), indicating that non-adrenergic, non-cholinergic effectors are not involved in regulating heart rate during activity. Blood pressure also increased during activity. Digestion was accompanied by an increase in heart rate from 25.6+/-1.3 to 47.7+/-2.2 min(-1) (N=8). In these animals, heart rate decreased to 44.2+/-2.7 min(-1) following propranolol infusion and increased to 53.9+/-1.8 min(-1) after infusion of atropine, resulting in small cholinergic and adrenergic tones (6.0+/-3.5 and 11.1+/-1.1 %, respectively). The heart rate of digesting snakes was 47.0+/-1.0 min(-1) after double autonomic blockade, which is significantly higher than the value of 36.1+/-1.4 min(-1) in double-blocked fasting animals at rest. Therefore, it appears that some other factor exerts a positive chronotropic effect during digestion, and we propose that this factor may be a circulating regulatory peptide, possibly liberated from the gastrointestinal system in response to the presence of food.

Adrenergic beta-Antagonists↗
PubMed2001

Lactate sequestration in the carapace of the crayfish Austropotamobius pallipes during exposure in air.

When held in air for up to 24 h, crayfish accumulated Ca(2+) and Mg(2+) in their haemolymph in direct proportion to raised levels of lactate. K(+) levels were highly variable, with elevated levels associated with morbidity. Lactate accumulation in the haemolymph was reflected in proportional increases in lactate levels in the carapace and muscle. Pieces of carapace incubated in saline containing elevated levels of lactate accumulated lactate to up to half the dissolved concentration. Measured levels in the carapace, relative to its water content, implied that lactate accumulated in the carapace in a combined form, possibly complexed to calcium. The exoskeleton seems to provide a reserve of buffering capacity and a sink for lactate during anaerobic metabolism. A similar mechanism has been identified in pond turtles.

Air↗
PubMed2001

A motivational interviewing intervention to increase fruit and vegetable intake through Black churches: results of the Eat for Life trial.

OBJECTIVES: This study reports on Eat for Life, a multicomponent intervention to increase fruit and vegetable consumption among African Americans that was delivered through Black churches. METHODS: Fourteen churches were randomly assigned to 3 treatment conditions: (1) comparison, (2) self-help intervention with 1 telephone cue call, and (3) self-help with 1 cue call and 3 counseling calls. The telephone counseling in group 3 was based on motivational interviewing. The primary outcome, assessed at baseline and 1-year follow-up, was fruit and vegetable intake as assessed by 3 food frequency questionnaires. RESULTS: Change in fruit and vegetable intake was significantly greater in the motivational interviewing group than in the comparison and self-help groups. The net difference between the motivational interviewing and comparison groups was 1.38, 1.03, and 1.21 servings of fruits and vegetables per day for the 2-item, 7-item, and 36-item food frequency questionnaires, respectively. The net difference between the motivational interviewing and self-help groups was 1.14, 1.10, and 0.97 servings for the 2-item, 7-item, and 36-item food frequency questionnaires, respectively. CONCLUSIONS: Motivational interviewing appears to be a promising strategy for modifying dietary behavior, and Black churches are an excellent setting to implement and evaluate health promotion programs.

Black or African American↗
PubMed2001

Heat resistance of Listeria monocytogenes.

The heat resistance data on Listeria monocytogenes in culture media and foods are summarized. Most heat resistance data for foods have been obtained in dairy, meat, poultry, and egg products. Limited data have been published on seafood, fruits, and vegetables. The methodologies employed have evolved over time; hence data from earlier experiments are not directly comparable to more recent studies. Many factors influence the heat resistance of L. monocytogenes. Variation exists among different strains in their ability to withstand heat treatment. In addition, heat resistance is influenced by age of the culture, growth conditions, recovery media, and characteristics of foods such as salt content, a(w), acidity, and the presence of other inhibitors. Listeriae are more heat resistant than most other nonspore-forming foodborne pathogens, and thus, processing recommendations based on data from experiments with Salmonella spp. or pathogenic Escherichia coli may not be sufficient to eliminate similar numbers of L. monocytogenes. The data provided in this review may prove useful for food processors in determining appropriate times and temperatures for producing foods free of vegetative pathogens.

Animals↗
PubMed2001

The respiratory consequences of feeding in amphibians and reptiles.

Many ectothermic vertebrates ingest very large meals at infrequent intervals. The digestive processes associated with these meals, often coupled with an extensive hypertrophy of the gastrointestinal organs, are energetically expensive and metabolic rate, therefore, increases substantially after feeding (specific dynamic action, SDA). Here, we review the cardio-respiratory consequences of SDA in amphibians and reptiles. For some snakes, the increased oxygen uptake during SDA is of similar magnitude to that of muscular exercise, and the two physiological states, therefore, exert similar and profound demands on oxygen transport by the cardiorespiratory systems. In several species, SDA is attended by increases in heart rate and overall systemic blood flows, but changes in blood flow distribution remain to be investigated. In snakes, the regulation of heart rate appears to involve a non-adrenergic-non-cholinergic mechanism, which may be a regulatory peptide released from the gastrointestinal system during digestion. Digestion is also associated with a net acid secretion to the stomach that causes an increase in plasma HCO3- concentration (the 'alkaline tide'). Experiments on chronically cannulated amphibians and reptiles, show that this metabolic alkalosis is countered by an increased P(CO2), so that the change in arterial pH is reduced. This respiratory compensation of arterial pH is accomplished through a reduction in ventilation relative to metabolism, but the estimated reductions in lung P(O2) are relatively small. The SDA response is also associated with haematological changes, but large interspecific differences exist. The studies on cardiorespiratory responses to digestion may allow for a further understanding of the physiological and structural constraints that limits the ability of reptiles and amphibians to sustain high metabolic rates.

Amphibians↗
PubMed2001

Boiler briquette coal versus raw coal: Part I--Stack gas emissions.

Stack gas emissions were characterized for a steam-generating boiler commonly used in China. The boiler was tested when fired with a newly formulated boiler briquette coal (BB-coal) and when fired with conventional raw coal (R-coal). The stack gas emissions were analyzed to determine emission rates and emission factors and to develop chemical source profiles. A dilution source sampling system was used to collect PM on both Teflon membrane filters and quartz fiber filters. The Teflon filters were analyzed gravimetrically for PM10 and PM2.5 mass concentrations and by X-ray fluorescence (XRF) for trace elements. The quartz fiber filters were analyzed for organic carbon (OC) and elemental carbon (EC) using a thermal/optical reflectance technique. Sulfur dioxide was measured using the standard wet chemistry method. Carbon monoxide was measured using an Orsat combustion analyzer. The emission rates of the R-coal combustion (in kg/hr), determined using the measured stack gas concentrations and the stack gas emission rates, were 0.74 for PM10, 0.38 for PM2.5, 20.7 for SO2, and 6.8 for CO, while those of the BB-coal combustion were 0.95 for PM10, 0.30 for PM2.5, 7.5 for SO2, and 5.3 for CO. The fuel-mass-based emission factors (in g/kg) of the R-coal, determined using the emission rates and the fuel burn rates, were 1.68 for PM10, 0.87 for PM2.5, 46.7 for SO2, and 15 for CO, while those of the BB-coal were 2.51 for PM10, 0.79 for PM2.5, 19.9 for SO2, and 14 for CO. The task-based emission factors (in g/ton steam generated) of the R-coal, determined using the fuel-mass-based emission factors and the coal/steam conversion factors, were 0.23 for PM10, 0.12 for PM2.5, 6.4 for SO2, and 2.0 for CO, while those of the BB-coal were 0.30 for PM10, 0.094 for PM2.5, 2.4 for SO2, and 1.7 for CO. PM10 and PM2.5 elemental compositions are also presented for both types of coal tested in the study.

Air Pollution↗