Latest News on Blood Disease : Nov 2020

Global burden of blood-pressure-related disease, 2001

Background

Few studies have assessed the extent and distribution of the blood-pressure burden worldwide. The aim of this study was to quantify the global burden of disease related to high blood pressure.

Methods

Worldwide burden of disease attributable to high blood pressure (≥115 mm Hg systolic) was estimated for groups according to age (≥30 years), sex, and World Bank region in the year 2001. Population impact fractions were calculated with data for mean systolic blood pressure, burden of deaths and disability-adjusted life years (DALYs), and relative risk corrected for regression dilution bias.

Findings

Worldwide, 7·6 million premature deaths (about 13·5% of the global total) and 92 million DALYs (6·0% of the global total) were attributed to high blood pressure. About 54% of stroke and 47% of ischaemic heart disease worldwide were attributable to high blood pressure. About half this burden was in people with hypertension; the remainder was in those with lesser degrees of high blood pressure. Overall, about 80% of the attributable burden occurred in low-income and middle-income economies, and over half occurred in people aged 45–69 years.

Interpretation

Most of the disease burden caused by high blood pressure is borne by low-income and middle-income countries, by people in middle age, and by people with prehypertension. Prevention and treatment strategies restricted to individuals with hypertension will miss much blood-pressure-related disease. [1]

Impact of High-Normal Blood Pressure on the Risk of Cardiovascular Disease

BACKGROUND

Information is limited regarding the risk of cardiovascular disease in persons with high-normal blood pressure (systolic pressure of 130 to 139 mm Hg, diastolic pressure of 85 to 89 mm Hg, or both).

METHODS

We investigated the association between blood-pressure category at base line and the incidence of cardiovascular disease on follow-up among 6859 participants in the Framingham Heart Study who were initially free of hypertension and cardiovascular disease.

RESULTS

A stepwise increase in cardiovascular event rates was noted in persons with higher base-line blood-pressure categories. The 10-year cumulative incidence of cardiovascular disease in subjects 35 to 64 years of age who had high-normal blood pressure was 4 percent (95 percent confidence interval, 2 to 5 percent) for women and 8 percent (95 percent confidence interval, 6 to 10 percent) for men; in older subjects (those 65 to 90 years old), the incidence was 18 percent (95 percent confidence interval, 12 to 23 percent) for women and 25 percent (95 percent confidence interval, 17 to 34 percent) for men. As compared with optimal blood pressure, high-normal blood pressure was associated with a risk-factor–adjusted hazard ratio for cardiovascular disease of 2.5 (95 percent confidence interval, 1.6 to 4.1) in women and 1.6 (95 percent confidence interval, 1.1 to 2.2) in men.

CONCLUSIONS

High-normal blood pressure is associated with an increased risk of cardiovascular disease. Our findings emphasize the need to determine whether lowering high-normal blood pressure can reduce the risk of cardiovascular disease. [2]

The Blood-Brain Barrier/Neurovascular Unit in Health and Disease

The blood-brain barrier (BBB) is the regulated interface between the peripheral circulation and the central nervous system (CNS). Although originally observed by Paul Ehrlich in 1885, the nature of the BBB was debated well into the 20th century. The anatomical substrate of the BBB is the cerebral microvascular endothelium, which, together with astrocytes, pericytes, neurons, and the extracellular matrix, constitute a “neurovascular unit” that is essential for the health and function of the CNS. Tight junctions (TJ) between endothelial cells of the BBB restrict paracellular diffusion of water-soluble substances from blood to brain. The TJ is an intricate complex of transmembrane (junctional adhesion molecule-1, occludin, and claudins) and cytoplasmic (zonula occludens-1 and -2, cingulin, AF-6, and 7H6) proteins linked to the actin cytoskeleton. The expression and subcellular localization of TJ proteins are modulated by several intrinsic signaling pathways, including those involving calcium, phosphorylation, and G-proteins. Disruption of BBB TJ by disease or drugs can lead to impaired BBB function and thus compromise the CNS. Therefore, understanding how BBB TJ might be affected by various factors holds significant promise for the prevention and treatment of neurological diseases. [3]

ABO and Rh Blood Group System and Periodontal Disease – A Prevalence Study

Background: Varied literature is documented exploring the relationship between ABO blood group and prevalence of oral and dental diseases. The aim of this study was to investigate the correlation of periodontal disease with “ABO” blood groups and Rhesus factor.

Materials and Methods: A total of 684 systemically healthy subjects who were non smokers were selected by chance. Subjects with known blood group who had at least 20 teeth, were included in the study and the blood groups were confirmed from their medical records. Based on the periodontal parameters like clinical attachment loss (CAL) and bleeding on probing (BOP) the subjects were divided into three groups: healthy, gingivitis and periodontitis. The percentage distribution of ABO blood groups and Rhesus factor among the groups was tabulated.

Results: There was an increased prevalence of gingivitis in subjects with blood group ‘A’ and periodontitis in subjects with blood group ‘O’, while subjects with blood group ‘B’ had healthy periodontium. There was higher prevalence of gingivitis in Rh positive group.

Conclusion: A significant relationship between blood typing and periodontal disease was determined in this study. Further research into this is indicated. [4]

Frequency Distribution of Hemoglobin Variants, ABO and Rhesus Blood Groups among Students of African Descent

Background: Hemoglobin variants, ABO and Rhesus blood groups are known to vary from one population to another. This study therefore sought to study the frequency of these indices among a cohort of Nigerian University students of African descent. The result will serve as a platform for instituting genetic counseling services with a view to reducing hemoglobinopathies.

Methods: Two hundred consenting students were recruited and screened for hemoglobin variants by standard alkaline cellulose acetate electrophoresis. ABO and Rhesus blood groups were determined by the hemagglutination technique.

Results: Of the 200 students aged 18 – 25 years that were screened, 123 (61.5%) were males and 77(38.5%) were females. Those with blood group O were the most prevalent (45%) followed by groups A (25.5%), B (25%) and AB (3.5%). Only 2 genotypes HbAA (78.5%) and HbAS (21.5%) were reported in this study. Rhesus D antigen was positive for 94.0% and negative for 6.0% of the study population.

Conclusions: The frequency of ABO and Rhesus blood groups appeared to be stable and consistent with reports from previous studies in Nigeria. Blood group O was the most prevalent. This also means there is a large pool of ‘’apparently’’ universal blood donors in this population. There was only one genotype variant reported (HbAS). This could imply a decline in hemoglobinopathies among Africans. Therefore the culture of genetic counseling must be encouraged and sustained. [5]

Reference

[1] Lawes, C.M., Vander Hoorn, S. and Rodgers, A., 2008. Global burden of blood-pressure-related disease, 2001. The Lancet, 371(9623), pp.1513-1518.

[2] Vasan, R.S., Larson, M.G., Leip, E.P., Evans, J.C., O’Donnell, C.J., Kannel, W.B. and Levy, D., 2001. Impact of high-normal blood pressure on the risk of cardiovascular disease. New England journal of medicine, 345(18), pp.1291-1297.

[3] Hawkins, B.T. and Davis, T.P., 2005. The blood-brain barrier/neurovascular unit in health and disease. Pharmacological reviews, 57(2), pp.173-185.

[4] Anup, P., Siddhartha, V., Girish, S., Keshava, A., Sameer, Z. and Vishwajeet, K. (2016) “ABO and Rh Blood Group System and Periodontal Disease – A Prevalence Study”, Journal of Advances in Medicine and Medical Research, 16(5), pp. 1-6. doi: 10.9734/BJMMR/2016/24055.

[5] Pennap, G. R., Envoh, E. and Igbawua, I. (2011) “Frequency Distribution of Hemoglobin Variants, ABO and Rhesus Blood Groups among Students of African Descent”, Microbiology Research Journal International, 1(2), pp. 33-40. doi: 10.9734/BMRJ/2011/196.

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