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Biomedical subjects

L C Yong

Publications and source records attributed to L C Yong.

At least 19 recordsLinked to original sources
PubMed1997

Intake of vitamins E, C, and A and risk of lung cancer. The NHANES I epidemiologic followup study. First National Health and Nutrition Examination Survey.

The relation between the dietary intake of vitamins E, C, and A (estimated by a 24-hour recall) and lung cancer incidence was examined in the First National Health and Nutrition Examination Survey Epidemiologic Followup Study cohort of 3,968 men and 6,100 women, aged 25-74 years. During a median follow-up period of 19 years (from 1971-1975 to 1992), 248 persons developed lung cancer. Adjusted for potential confounders using Cox proportional hazards regression methods with age as the underlying time variable, the relative risk of lung cancer for subjects in the highest quartile of vitamin C intake compared with those in the lowest quartile was 0.66 (95% confidence interval (CI) 0.45-0.96). For vitamin A intake, a protective effect was observed only for its fruit and vegetable component (carotenoids) among current smokers (relative risk = 0.49, 95% CI 0.29-0.84), but this was modified by the intensity of smoking (a statistically significant effect (relative risk = 0.33, 95% CI 0.13-0.84) was observed only for those in the lowest tertile of pack-years of smoking). The vitamin E intake-lung cancer relation was modified by the intensity of smoking with a significant protective effect confined to current smokers in the lowest tertile of pack-years of smoking (relative risk = 0.36, 95% CI 0.16-0.83). Overall, there was no additional protective effect of supplements of vitamins E, C, and A beyond that provided through dietary intake. When vitamin E, vitamin C, and carotenoid intakes were examined in combination, a strong protective effect was observed for those in the highest compared with those in the lowest quartile of all three intakes (relative risk = 0.32, 95% CI 0.14-0.74). These data provide support for a protective role of dietary vitamins E and C and of carotenoids against lung cancer risk but with a modification in effects by the intensity of cigarette exposure. While smoking avoidance is the most important behavior to reduce lung cancer risk, the daily consumption of a variety of fruits and vegetables that provides a combination of these nutrients and other potential protective factors may offer the best dietary protection against lung cancer.

Adult↗
PubMed1997

The mast cell: origin, morphology, distribution, and function.

The mast cell remains an enigmatic cell more than 100 years after its discovery by Paul Ehrlich at the turn of the century. It is a cell that is found widely distributed in the body particularly associated with connective tissues. It can be recognised by its content of metachromatic granules when appropriately fixed and stained with metachromatic dyes such as toulidine blue. The metachromatic granules of the mast cell remain an important differentiating characteristic from other cells although it is by no means absolute. In the early days of its discovery it was thought to originate from primitive mesenchyme, thymocyte or lymphocyte. More recent evidence suggests that it may have originated from the monocyte. Current evidence points to an origin from haemopoietic tissue in the bone marrow, the progenitors differentiate from primitive cells under the influence of cytokines (IL3), migrate to other body sites and then undergo differentiation and maturation under the influence of growth and other factors. The mast cell has many functions exerted through its ability to produce a host of biologically active substances the most notable being heparin, serotonin, dopamine, tryptase and chymase. These substances may be released in response to immunological and neural stimuli. Mast cells are found to be functionally heterogeneous, possibly site specific and have the ability to adapt to their environment, producing secretions commensurate with the needs of any situation. The mast cell is involved in immunological, neoplastic, inflammatory and other conditions. Much about its function has been unravelled but there remains more to be uncovered.

Animals↗
PubMed1996

Prospective study of relative weight and risk of breast cancer: the Breast Cancer Detection Demonstration Project follow-up study, 1979 to 1987-1989.

Despite extensive research on obesity and breast cancer in recent decades, inconsistencies in the literature exist. The authors examined prospectively the relation between adult relative weight (weight (kg)/height (m)1.5) and breast cancer risk in a cohort of 54,896 women aged 31-89 years who had previously participated in the Breast Cancer Detection Demonstration Project. During a mean follow-up period of 7 years, 226 of the premenopausal women and 1,198 of the postmenopausal women developed breast cancer. Analysis was performed using Cox proportional hazards regression methods with age as the underlying time variable and adjusted for the effects of potential confounders. Among postmenopausal women, the risk of breast cancer increased with increasing relative weight (p < 0.05 for trend); relative risk for the highest compared with the lowest quintile for relative weight was 1.3 (95% confidence interval (CI) 1.1-1.6). This association was modified by age at diagnosis, with relative risks of 1.1 (95% CI 0.8-1.4), 1.2 (95% CI 0.8-1.7), and 1.8 (95% CI 1.3-2.5), respectively, for women aged < 60, 60-64, and > or = 65 years. The higher risk of breast cancer among the older and overweight women was largely confined to women whose weights were measured during the postmenopausal but not the premenopausal period. This risk pattern was observed among the naturally menopausal women, but was also apparent in the smaller group of women with bilateral oophorectomy or hysterectomy with one ovary retained. Among premenopausal women, adult relative weight was not associated with breast cancer risk. These findings suggest that the inconsistencies in the literature on obesity and breast cancer may be due in part to the differing age distributions of the populations studied. The authors conclude that prevention of obesity throughout adulthood, particularly after menopause, may help reduce breast cancer among older women.

Adult↗
PubMed1995

Nephrotoxicity of notexin in experimental mice.

Notexin, a well known neurotoxin, derived from tiger snake venom, was shown to have direct nephrotoxic properties in experimental mice. A single subcutaneous dose of 1.38 micrograms/kg body weight of notexin produced renal tubular and glomerular damage within 24 hours. Renal damage increased in severity proportional to the dose of notexin injected. At a high dose of notexin, thrombotic "spherules" were found in glomeruli. These thrombotic spherules have not been previously reported to be associated with notexin or snake venoms.

Animals↗
PubMed1995

Effect of alcohol consumption on plasma carotenoid concentrations in premenopausal women: a controlled dietary study.

This 6-mo controlled dietary study compared the effect of 30 g alcohol/d for three menstrual cycles with three alcohol-free cycles on plasma carotenoid concentrations in 18 nonsmoking, premenopausal women. Participants were randomly allocated within a crossover design to either phase and consumed approximately 6 mg total carotenoids/d under isoenergetic conditions. Blood was drawn during the third menstrual cycle of each alcohol phase. After adjustment for the mean daily specific carotenoid and energy intakes for each alcohol phase, the paired differences in mean plasma alpha- and beta-carotene concentrations were significantly higher by 19% (P = 0.027) and 13% (P = 0.034), respectively, during the alcohol-intake phase of the study. The paired difference in mean plasma lutein/zeaxanthin concentration was significantly lower by 17% (P = 0.031) when the participants consumed alcohol than when they did not. This is the first reported study in women to document the independent effect of alcohol on plasma carotenoid concentrations without the potential interaction of smoking under controlled dietary conditions.

Adult↗
PubMed1995

Development of risk factors for cardiovascular disease among women from adolescence to older ages.

The development of risk factors for young adults to older ages for women has been evaluated in several studies. The increase in risk factor levels is related to age, weight gain, and diet. The levels of risk factors are related to extent of atherosclerosis, even at relatively young ages. The prevention of increase in risk factors is of primary importance for the future reduction of morbidity and mortality due to cardiovascular disease.

Adolescent↗
PubMed1994

Tracking of blood pressure from adolescence to middle age: the Dormont High School Study.

METHODS: Tracking of blood pressure was studied in a cohort of 86 men and 116 women, initially examined at mean age 17 years and re-examined at mean ages 34 and 47 years in the Dormont High School Follow-up Study. RESULTS: Correlations for systolic blood pressure (men vs women, P < 0.05) were r = 0.42 vs r = 0.39 between mean ages 17 and 34 years; r = 0.38 vs r = 0.54 between mean ages 34 and 47 years; and r = 0.27 vs r = 0.24 between mean ages 17 and 47 years. For diastolic blood pressure, the correlations were lower, but were higher among women than men, and were higher between mean ages 34 and 47 years (r = 0.44 for men and r = 0.54 for women, P < 0.001) than at earlier ages. The correlations for weight were higher than those for blood pressure (men vs women, P < 0.001): r = 0.64 vs r = 0.59 between mean ages 17 and 34 years; r = 0.88 vs r = 0.81 between mean ages 34 and 47 years; and r = 0.58 vs r = 0.49 between mean ages 17 and 47 years. With increase in age and length of follow-up, there was a stronger tendency for those in the extreme tertiles of the blood pressure distribution to maintain their ranks. The significance and magnitude of the blood pressure correlations remained essentially unchanged after adjustment for weight and its changes. However, weight was related to the changes in blood pressure tracking status, but this varied with age. CONCLUSION: These data suggest that the age and gender differences in the degree of blood pressure tracking may be a function of the tracking of weight as well as a reflection of the gender difference in the consistency of the relationship of blood pressure to weight at different ages.

Adolescent↗
PubMed1994

Relationship between dietary intake and plasma concentrations of carotenoids in premenopausal women: application of the USDA-NCI carotenoid food-composition database.

The diet-plasma relationships for carotenoids were examined in a group of 98 nonsmoking premenopausal women who participated in the cross-sectional phase of the National Cancer Institute (NCI)-US Department of Agriculture (USDA) diet study on alcohol-hormone metabolism, 1988-90. With use of the newly developed USDA-NCI carotenoid food-composition database, the mean daily intakes of carotenoids were significantly higher when estimated from the food-frequency questionnaire (FFQ) than from the 7-d diet records. Lycopene (mean = 0.58 mmol/L), lutein plus zeaxanthin (mean = 0.46 mmol/L), and beta-carotene (mean = 0.34 mmol/L) were the major plasma carotenoids. After adjustment for body mass index, energy and alcohol intakes, and total plasma cholesterol concentration, the following significant correlation (P < 0.05) were observed between the diet record and the FFQ-estimated carotenoid intakes and their respective plasma concentrations: alpha-carotene (r = 0.58 vs 0.49), beta-carotene (r = 0.51 vs 0.49), beta-cryptoxanthin (r = 0.49 vs 0.36), lutein plus zeaxanthin (r = 0.31 vs 0.37), lycopene (r = 0.50 vs 0.26), and total carotenoids (r = 0.57 vs 0.49). These data indicate that plasma carotenoid concentrations are reflective of dietary intake, but the magnitude of the correlation varies depending on the specific carotenoid and on the dietary assessment tool.

Adult↗
PubMed1993

Longitudinal study of blood pressure: changes and determinants from adolescence to middle age. The Dormont High School follow-up study, 1957-1963 to 1989-1990.

The changes and determinants of blood pressure were examined in the Dormont High School (Pittsburgh, Pennsylvania) cohort of 86 men and 116 women with mean ages of 17 years during high school (1957-1963), 34 years at follow-up I (1977-1978), and 47 years at current follow-up II (1989-1990). Over the 30-year period, the subjects' mean systolic blood pressure changed relatively little, whereas the increase in mean diastolic blood pressure was significantly higher in men than in women (p < 0.01). Based on the criteria of diastolic blood pressure > or = 90 mmHg, and/or current use of antihypertensive medication, 18% developed hypertension. Compared with nonhypertensives, hypertensives had significantly higher baseline systolic blood pressure (p < 0.001); higher weight at all ages (p < 0.05); and gained more weight over the period (p < 0.01). By means of multivariate analyses, it was found that baseline systolic blood pressure, current weight, and weight gain were significantly and independently associated with current systolic blood pressure level and hypertension. These data indicate that initial systolic blood pressure level at adolescence, current weight, and weight gain are important determinants of risk of high blood pressure, and there is a further suggestion of sex and age differences in the critical period of risk.

Adolescent↗
PubMed1993

The correlation between two dietary assessments of carotenoid intake and plasma carotenoid concentrations: application of a carotenoid food-composition database.

A newly available carotenoid food-composition database providing specific carotenoid values for > 2300 foods was linked to dietary data on 57 male nonsmokers to examine the association between dietary carotenoid intake and plasma carotenoid concentrations over 3 wk when free-living. Carotenoid intake was estimated from a food-frequency questionnaire (FFQ) and 7 d of food diaries with concurrent analysis of plasma carotenoid concentrations. After adjustment for energy intake, percentage of energy from alcohol, and plasma lipid concentrations, significant diet-plasma correlations for the FFQ and the food diaries (FD) included alpha-carotene (r = 0.29 and 0.43), beta-carotene (r = 0.36 FFQ only), beta-cryptoxanthin (r = 0.46 and 0.44), lutein (r = 0.44 FD only), and lycopene (r = 0.53 FD only). Dietary carotenoid intakes were associated with plasma carotenoid concentrations for all the carotenoids except for beta-carotene when food diaries were used whereas the diet-plasma correlation for the provitamin A carotenoids were consistently significant when the FFQ was used.

Adult↗
PubMed1992

Proliferative glomerulonephritis in mice induced by sea snake (Aipysurus laevis) venom.

Aipysurus laevis venom has been shown to have a direct nephrotoxic effect in mice. A single subcutaneous injection (0.075 mg/kg body wt.) of the whole venom caused acute renal tubular degeneration and proliferative glomerulonephritis. The tubular changes appeared within 1 hour and remained for at least 14 days. Mesangial proliferative glomerulonephritis developed within 3-10 days, and is characterised by mild mesangial proliferation, mesangial and glomerular basement membrane deposits. This is followed by a partial resolution and subsequent mesangial sclerosis. The exact pathogenesis of venom-induced glomerulonephritis is not clear although it may have an immunological basis similar to that seen in human poststreptococcal glomerulonephritis. It was not possible to clarify the nature of the deposits by conventional immunohistochemical stains.

Animals↗
PubMed1991

A comparative study of cultured vascular and lymphatic endothelium.

There is comparatively little knowledge of the structure and function of cultured lymphatic endothelium. A study was carried out to compare the intrinsic growth characteristics of cultured lymphatic endothelial cells with cultured endothelial derived from blood vessels. It was found that cultured lymphatic endothelium has growth requirements and growth characteristics similar to vascular endothelium. It also possesses FVIIIRA and Weibel-Palade bodies for specific identification. The results of this study have provided important base line data for subsequent studies of the pathobiology of lymphatic endothelium.

Animals↗
PubMed1990

The clearance of heterologous antibodies in experimental antibasement membrane antibody mediated glomerulonephritis.

A study of the clearance of anti GBM antibodies is important for an understanding of the pathogenesis of Goodpasture's syndrome. This paper reports a study of the sequential clearance of heterologous anti-glomerular basement membrane antibodies in the neonatal rat. A single intraperitoneal injection was followed by rapid and linear binding of injected antibodies to glomerular basement membranes, particularly to those glomeruli in the corticomedullary region. GBM bound antibodies were cleared gradually through the mesangium and significant amounts of antibodies still remained bound after 6 months. Subsequent injections of antibodies failed to provoke morphological abnormalities. These experiments have shown that the glomerular basement membrane of neonatal and adult rats possesses similar antigenic sites. The mesangium plays a major role in the clearance of injected heterologous antibodies. The slow clearance of antibodies from the GBM indicates a strong affinity of antibodies to antigenic sites and that the removal of antibodies is intimately related to the slow metabolic turnover of the glomerular basement membrane. The findings help to explain some of the observations in human antibasement membrane antibody mediated disease of the Goodpasture's type.

Animals↗
PubMed1988

The effect of oxygen toxicity and cigarette smoking on the binding of heterologous antibodies to alveolar basement membrane in the rat.

It has been suspected that pulmonary lesions of the Goodpasture type may be the result of circulating antibodies to alveolar basement membrane and that environmental factors such as cigarette smoke may influence antibody binding. Carefully designed experiments in this study have shown that exposure to cigarette smoke for 3 weeks or 100% oxygen for 65 h did not influence the binding of heterologous antibodies to alveolar basement membrane in Wistar rats, nor did these regimes increase any pathological changes associated with the antibody binding as detected by light microscopy. The results which are at variance with other reported findings are discussed with reference to reported animal models of antibody mediated pneumonitis and Goodpasture's syndrome in man.

Animals↗
PubMed1987

Culture and characterization of bovine mesenteric lymphatic endothelium.

Lymphatic endothelial cells isolated from bovine mesenteric lymphatic vessels were cultured and characterized. Lymphatic endothelial cells grew as a monolayer displaying an elongated morphology in preconfluent primary cultures. When confluent, the cells exhibited a polygonal morphology to form a "cobblestone" pattern previously described for cultured vascular endothelium. All culture lymphatic endothelial cells expressed Factor VIII-related antigen and bound Ulex europaeus I lectin. Ultrastructurally, cultured lymphatic endothelium was characterized by the presence of Weibel-Palade bodies as well as the usual cytoplasmic organelles.

Animals↗
PubMed1987

Cardiovascular lesions in experimental acute and chronic renal failure in the rat.

Adult Wistar rats were subjected to partial or total nephrectomy or injected with mercuric chloride to induce a state of acute or chronic renal failure. They developed sequential pathological changes in the cardiovascular system characterized by fibrin deposition in the pericardium and fibrinoid changes in many systemic arteries and arterioles. Focal myocardial necrosis and interstitial fibrosis were a feature of long term chronic renal failure. Increased vascular permeability was evident in the pericardium of rats with chronic renal failure especially when autologous blood was also injected into the pericardial sac of previously nephrectomized rats.

Acute Kidney Injury↗