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Biomedical subjects

R Chakrabarti

Publications and source records attributed to R Chakrabarti.

At least 91 records · Page 5Linked to original sources
PubMed1980

Haemostatic function and cardiovascular death: early results of a prospective study.

Components of the haemostatic system which may be involved in the pathogenesis of ischaemic heart disease (IHD) were measured in the Northwick Park Heart Study. Of 1510 white men aged 40-64 at recruitment, 49 have since died. 27 died from cardiovascular disease (IHD in all but 3), 18 from cancer, and 4 from other causes. The mean recruitment levels of factor VIIc, factor VIIIc, and fibrinogen were significantly higher in those who died of cardiovascular disease than in those who survived. The independent associations of factor VIIc and fibrinogen with cardiovascular death were at least as strong as the association of blood cholesterol with cardiovascular death. A clustering of two or three high clotting-factor values (factor VIIc, factor VIIIc, and fibrinogen) was present at recruitment in 63% of those who died of cardiovascular disease, compared with 23% of those who survived. The clotting-factor results appeared to be specific for cardiovascular disease: there was no evidence that high levels of factor VIIc, factor VIIIc, and fibrinogen were associated with death from cancer. The general epidemiology of factor VIIc, factor VIIIc, and fibrinogen is consistent with their having a role in the pathogenesis of IHD.

Adult↗
PubMed1979

Haemostatic variables associated with diabetes and its complications.

To study the possible role of an "increased thrombotic tendency" in the vascular complications of diabetes several tests of haemostatic function were carried out on 91 men and 63 women with diabetes aged 35-54 years and the results compared with findings in 686 men and 393 women of the same age in the Northwick Park Heart Study. Mean values for factors VII and X, fibrinogen, and platelet adhesiveness were higher in the diabetics, but mean fibrinolytic activity and whole blood platelet counts were lower. Antithrombin III values were also higher in the diabetics, which may have constituted a protective response to other changes favouring the onset of vascular disease. Diabetics with retinopathy had higher factor VII and antithrombin III values, and those with proteinuria had higher values for factor VII, fibrinogen, and platelet adhesiveness than those without these complications. These findings suggest a potentially important association between a thrombogenic tendency and vascular disease in diabetes. Nevertheless, prospective data are needed to clarify whether the haemostatic abnormalities precede the onset of clinically manifest vascular complications or are a consequence of them.

Adult↗
PubMed1979

Characteristics affecting fibrinolytic activity and plasma fibrinogen concentrations.

As part of a study to determine the extent to which the haemostatic system is implicated in the onset of clinically manifest ischaemic heart disease, characteristics influencing fibrinolytic activity (FA) and plasma fibrinogen concentrations were examined in 1601 men aged 18-64 and 707 women aged 18-59 in several occupational groups in North-west London. In men FA noticeably decreased till the age of about 58, when there was a small rise. In women a small increase in FA between 18 and about 40 was followed by a slightly larger fall between 40 and 59. There was a pronounced negative association of FA with obesity. FA was significantly less in smokers than non-smokers, though the effect was not large. FA increased with alcohol consumption. FA in men appeared to be greatest in the lower social classes, and men on night shift had poorer FA than those on day work. FA was greater in women using oral contraceptives than in those not using these preparations. In both sexes FA increased with exercise, but there were no associations between any of the characteristics studied and the increase. Plasma fibrinogen concentrations increase with age and obesity, are higher in smokers than non-smokers, and fall with alcohol consumption. In women the concentrations are higher in those using oral contraceptives. The general epidemiology of FA and plasma fibrinogen concentrations suggests that they may well be implicated in the pathogenesis of ischaemic heart disease.

Adolescent↗
PubMed1979

Relationship of air temperature to various chemical, haematological, and haemostatic variables.

Results for biochemical and haematological variables have been correlated with data on atmospheric temperature in order to identify possible mechanisms through which low environmental temperature may increase mortality from myocardial infarction and cerebrovascular disease. With the exception of cholesterol, there were no associations in the case of several clinical chemistry variables, or of haemoglobin and related indices. With varying degrees of consistency among the sex and age groups studied, temperature was positively correlated with factor VII, antithrombin III, and cholesterol, and negatively correlated with fibrinolytic activity. The correlations were all low but may offer some clues to mechanisms whereby air temperature influences ischaemic heart and cerebrovascular disease mortality.

Adolescent↗
PubMed1978

The effect of plasma fibrinogen levels on measures of fibrinolytic activity.

It has been claimed that lysis time methods may be inappropriate as measures of fibrinolytic activity on the grounds that they are largely determined by plasma fibrinogen levels. The dilute blood clot lysis time (DBCLT) has therefore been measured in 103 subjects; fibrinolytic activity (expressed as 100/DBCLT) has been compared with the fibrin plate area (FPA) lysed by the euglobulin fraction, the latter method being, of course, virtually independent of plasma fibrinogen. Plasma fibrinogen levels have also been measured; they ranged from 167 to 416 mg%. Results have been analysed by the technique of multiple regression. The incorporation of plasma fibrinogen levels in the regression equation relating 100/DBCLT to FPA does not result in a significant increase in the proportion of the variance in 100/DBCLT that can be explained. It is concluded that there is no evidence that DBCLT is influenced by plasma fibrinogen levels within the physiological range.

Female↗
PubMed1977

Haemostatic, lipid, and blood-pressure profiles of women on oral contraceptives containing 50 microgram or 30 microgram oestrogen.

In 15 women on oral contraceptives containing 30 microgram oestrogen, mean values for factors II, VII, and X, fibrinogen, fibrinolytic activity, antithrombin III, cholesterol, and fasting triglycerides were intermediate between values for 63 women on preparations containing 50 microgram oestrogen and those for 243 premenopausal women not on oral contraceptives. Mean blood-pressure levels, however, were higher in women on 30 microgram than in those on 50 microgram preparations. In 28 women on 50 microgram preparations containing 3 mg or 4 mg norethisterone, mean values of factor VII, fibrinogen, fibrinolytic activity, cholesterol, fasting triglycerides, and systolic blood-pressure were higher than in 15 women whose preparations contained only 1 mg of norethisterone. A less consistent picture was found in women on 30 microgram oestrogen preparations containing either 250 microgram (10 women) or 150 microgram (5 women) d-norgestrel. It is concluded that 30 microgram oestrogen preparations probably result in smaller hemostatic and lipid changes than 50 microgram preparations but that they may have a blood-pressure-raising effect attributable to the particular progestagen, d-norgestrel, used in 30 microgram preparations. The safety of these 30 microgram oestrogen preparations may thus depend partly on the balance between these two sets of effects. It is also concluded that norethisterone may have effects similar to those attributed to oestrogens.

Adult↗
PubMed1977

Changes in haemostatic system after application of a tourniquet.

In 35 patients undergoing routine orthopaedic operations in which occlusive tourniquets were used there was a pronounced rise in fibrinolytic activity in the systemic circulation which lasted for at least 15 minutes after the release of the tourniquet; this response was seen after operations on both arms and legs. In contrast there was no increase in fibrinolytic activity in the systemic circulation associated with venous occlusion. Neither the application of a tourniquet nor venous occlusion resulted in changes in factors V or VIII, fibrinogen, or platelet-count. The application of a completely occlusive tourniquet might be a simple form of prophylaxis against deep-vein thrombosis and would avoid the disadvantages of using heparin.

Adult↗
PubMed1976

Factor V in an industrial population.

Factor-V levels have been measured in a random sample of 626 men and 307 women working in a variety of occupations in North West London. The method is an automated one-stage assay using the same batch of freeze-dried thromboplastin, all results being expressed in terms of the same freeze-dried standard plasma; it has been shown that only one dilution of test plasma is necessary. Factor-V levels are significantly higher when venepuncture is difficult than when it is satisfactory, the mean levels being about 130% and 117% respectively. Factor-V levels are approximately normally distributed; they are similar in men and women and in blacks and whites, and increase significantly with age at the rate of about 0.6% per annum. Factor-V levels are not affected by oral contraceptives or the menopause, and there are no differences according to blood group or secretor status.

Adult↗