Biomedical subjects

A R Ness

Publications and source records attributed to A R Ness.

45 records · Page 3Linked to original sources

PubMed1996

Vitamin C status and blood pressure.

OBJECTIVE: To examine the cross-sectional relationship between blood pressure and plasma vitamin C. DESIGN: A cross-sectional analysis. SETTING: A population-based study. SUBJECTS: The subjects were 835 men and 1025 women aged 45-75 years registered with general practices in Norfolk. INTERVENTIONS: Completion of health and lifestyle questionnaire and attendance for a health check. MAIN OUTCOME MEASURES: Diastolic blood pressure (DBP), systolic blood pressure (SBP) and plasma vitamin C level. RESULTS: The mean SBP was 135.8 +/- 18.5 mmHg (mean +/- SD) and the mean DBP was 82.5 +/- 11.3 mmHg. The mean plasma vitamin C level was 52.6 +/- 19.7 mumol/l. The plasma vitamin C level was negatively correlated both with SBP and with DBP. These correlations persisted after adjustment for age, sex and body mass index. Adjusting for other confounders including cigarette smoking, physical activity and alcohol intake did not alter the observed association. Exclusion of subjects taking vitamin supplements and those with known hypertension did not affect the results. The differences in SBP and in DBP for a 50 mumol/l difference in vitamin C, estimated using linear regression, were -3.6 and -2.6 mmHg, respectively. CONCLUSIONS: The plasma vitamin C level may be a marker of other factors; nevertheless, these results are consistent with other published work indicating that a high intake of vitamin C from food confers protection against raised blood pressure and strokes.

Aged↗

PubMed1996

Vitamin C status and respiratory function.

OBJECTIVE: To examine the cross sectional relationship between respiratory function and plasma vitamin C. DESIGN: Cross sectional analysis. SETTING: Population based study. SUBJECTS: 835 Men and 1025 women aged 45 to 75 registered with GP practices in Norfolk. INTERVENTIONS: Completion of health and lifestyle questionnaire and attendance for a health check. MAIN OUTCOME MEASURES: Forced expiratory volume in one second (FEV1), forced vital capacity (FVC) and non fasting plasma vitamin C. RESULTS: Plasma vitamin C was positively correlated, after adjustment for age and height, with both FEV1 (r = 0.17, P < 0.001) and FVC (r = 0.14, p < 0.001) in men. The association in women was weaker and not statistically significant. Adjusting for other possible factors and exclusion of various groups did not alter the observed associations. The differences in FEV1 and FVC in men, adjusted for age, height and cigarette smoking, for a 50 micromol/L difference in vitamin C were 0.22 litres (95% CI 0.10-0.33) and 0.23 litres (95% CI 0.09-0.37) respectively. The population distribution was shifted such that 12.1% of men with vitamin C levels < or = 30 micromol/L had an FEV1 of less than two litres, compared with 4.6% with levels > or = 60 micromol/L. CONCLUSIONS: These findings are consistent with other studies of vitamin C and respiratory function and suggest that vitamin C may be protective for lung function through the whole normal range of dietary intake and lung function.

Aged↗

PubMed1996

Vitamin C status and serum lipids.

OBJECTIVES: To examine the cross sectional relationship between plasma vitamin C and serum lipids. DESIGN: Cross-sectional analysis. SETTING: Population based study. SUBJECTS: 835 Men and 1025 women aged 45-75 registered with GP practices in Norfolk. INTERVENTIONS: Completion of health and lifestyle questionnaire and attendance for a health check. MAIN OUTCOME MEASURES: Non fasting plasma vitamin C and serum lipids. RESULTS: Plasma vitamin C was not correlated with serum total cholesterol or LDL cholesterol in men or women. In women plasma vitamin C was positively correlated with HDL cholesterol r = 0.15 (P < 0.001) and negatively correlated with triglyceride r = -0.17 P < 0.001). These correlations persisted after adjustment for age and body mass index. The association in men was weaker and after adjustment for age and body mass index was no longer statistically significant. Exclusion of subjects taking vitamin supplements and those with known hyperlipidaemic did not affect the findings. The difference in HDL cholesterol, adjusted for age, body mass index and alcohol intake, for a 50 micromol/l difference in vitamin C, estimated using linear regression, was 0.11 mmol/l in women. The difference in triglyceride, adjusted for age and body mass index was -0.16 mmol/l in women. CONCLUSIONS: Plasma vitamin C level may be a marker of other factors; nevertheless these results are consistent with other published work indicating that a high intake of vitamin C from food raises serum HDL cholesterol and lowers serum triglyceride.

Aged↗

PubMed1996

Vitamin C and cardiovascular disease: a systematic review.

BACKGROUND: Laboratory studies suggest that antioxidants, such as Vitamin C, are important inhibitors of atherosclerotic lesions. Most epidemiological reviews have considered all antioxidants together. This review seeks to clarify the current state of knowledge specifically concerned with vitamin C. METHODS: All ecological studies, case-control studies, prospective studies and trials in humans that examined the association between vitamin C intake or blood levels of vitamin C and cardiovascular disease were included. Relevant references were located by MEDLINE search for articles published from 1966 to 1996, by an EMBASE search for articles published from 1980 to 1996, by searching personal bibliographies, books and reviews and from citations in located articles. RESULTS: For coronary heart disease four of seven ecological studies, one of four case-control studies and three of 12 cohort studies found a significant protective association with vitamin C intake or status. For strokes two of two ecological studies, none of one case-control study and two of seven cohort studies found a significant protective association. For total circulatory disease, two of three cohort studies reported a significant protective association. CONCLUSIONS: The evidence, albeit limited, is consistent with vitamin C having protective effect against stroke whereas the evidence that vitamin C is protective against coronary heart disease is less consistent. The lack of an association for coronary heart disease could be explained in terms of there being a true lack of effect, dietary measurement error, a threshold effect, and effect of seasonal variations in intake, an interaction with other dietary constituents or a relatively short duration of follow-up.

Ascorbic Acid↗

PubMed1977

A study of the arrangement of osteoblasts of rat calvarium cultured in medium with, or without, added parathyroid extract.

The osteoblast layers on the inner surfaces of the half-calvaria of neonatal rats of 2 litters were studied by scanning electron microscopy. Some halves were fixed immediately on dissection. Others were carried through incubation in an Eagle's medium, with or without the addition of parathyroid extract (PTE): for 2, 4, 8 or, most importantly, 24 h. In their initial state, presumed as like the o-h material, the osteoblasts presented as a dense tesselation. After 24 h of culture in the medium, osteoblasts were more sparse in the fields examined and although, in a set of 4 preparations, they retained significant alignment, their orientation had become more random. In addition, they were broader and larger in area. By contrast, with PTE added to the medium, osteoblasts almost maintained their number per field, did maintain their cell area, but became longer and narrower and strikingly parallel in their array. The aligning effect of the PTE preceded, and thus was independent of, its elongating effect.

Animals↗

PubMed1971