Effect of Red Blood Cell Aggregation on Tube Flow
Oguz Baskurt, Björn Neu, Herbert J. Meiselman in Red Blood Cell Aggregation, 2011
Understanding blood flow in the circulatory system has attracted scientific interest for several centuries, with perhaps the most notable early work being the 1628 publication of An Anatomical Study of the Motion of the Heart and of the Blood in Animals by William Harvey. However, due to technical difficulties in conducting appropriate experiments in the vasculature of living organisms, blood flow studies until early in the twentieth century were mostly based on observations in cylindrical tubes. Therefore, observations on blood flow in narrow tubes have provided the majority of basic information on blood flow dynamics, including the influence of red blood cell (RBC) properties. These early studies on blood flow in cylindrical tubes are briefly summarized in this chapter, with more detailed information available elsewhere (Goldsmith et al. 1989).
Comparative Aspects of Red Blood Cell Aggregation
Oguz Baskurt, Björn Neu, Herbert J. Meiselman in Red Blood Cell Aggregation, 2011
It is well known that the aggregation of red blood cells (RBC) as discussed in this book is a mammalian feature. Mammalian RBC do not contain a nucleus or other organelles, while all nonmammalian species, including avian, reptile, and fish, are characterized by nucleated RBC (see frog RBC in Figure 9.1e as an example). Primarily due to an extensive degree of evolution, RBC in mammalian species are usually biconcave discs (Figure 9.1) with only a few exceptions (e.g., camelids, Figure 9.1c). This special geometry of RBC is common for all sub and infraclasses of the Mammalian class, including placental mammals, marsupials, and monotremes (Baskurt et al. 2010) that represent the first diversification of Mammalia dating back ~200 million years (Grutzner et al. 2003). It has been suggested that this special geometry evolved to optimize blood flow in the circulatory system (Uzoigwe 2006).
‘The anatomy of the blood’
Andrew Cunningham in ‘I Follow Aristotle’:How William Harvey Discovered the Circulation of the Blood, 2022
Before Harvey’s discovery of the circulation of the blood, blood and its composition had not been something that anatomists discussed. Blood-letting was an extremely common medical intervention, and continued to be so after Harvey, with Harvey himself continuing to support it. However, two groups of young investigators in France and England, now knowing that the blood circulated in all animals, began to think about the possibility of transfusing blood from one animal to another, and indeed even from animals to humans; that is, until one of the French transfusees died. Other people, using their microscopes, began to look at blood to determine its make-up and structure. Between them they began to make the blood a new research object.
Effects of hormone therapy on ambulatory blood pressure in postmenopausal Korean women
Published in Climacteric, 2011
D-Y. Lee, J-Y. Kim, J-H. Kim, D-S. Choi, D-K. Kim, K. K. Koh, B-K. Yoon
Background Previous studies of the effects of postmenopausal hormone therapy (HT) on blood pressure have yielded inconsistent results. Objectives To examine the impact of HT on 24-h ambulatory blood pressure. Methods A total of 67 postmenopausal Korean women (age 57.1 ± 5.7 years) received 2 months of HT consisting of conjugated equine estrogen (CEE, 0.625 mg/day) with or without micronized progesterone (100 mg/day). Ambulatory blood pressure monitoring was performed at baseline and after HT. Subjects were divided into those with normal blood pressure (n == 25) and those with high blood pressure (n == 42), based on their baseline daytime blood pressure. Results Parity and body mass index were higher in the group with high blood pressure than in the group with normal blood pressure. For both systolic and diastolic blood pressures throughout the day, significant negative correlations were observed between basal blood pressure and blood pressure difference after HT. During the daytime period, HT increased systolic and diastolic blood pressures in the subjects with normal blood pressure and decreased systolic and diastolic blood pressures in those with high blood pressure. When micronized progesterone was added to the CEE treatment, the increase in daytime blood pressure in the group with normal blood pressure was abolished, and the decrease in systolic blood pressure throughout the day in the group with high blood pressure was potentiated. Conclusions HT had either blood pressure-elevating or blood pressure-lowering effects in postmenopausal Korean women, depending on basal blood pressure. CEE increased the daytime blood pressure in women with normal blood pressure, but reduced it in women with high blood pressure. Micronized progesterone may provide beneficial effects on blood pressure when combined with CEE.
CURRENT PERCEIVED RISKS OF TRANSFUSION IN THE UK AND RELEVANCE TO THE FUTURE ACCEPTANCE OF BLOOD SUBSTITUTES
Published in Artificial Cells, Blood Substitutes, and Biotechnology, 2001
K. C. Lowe, K. Farrell, E. M. P. Ferguson, V. James
Data has been gathered on the perception of risk associated with blood donation and transfusion (including the use of so-called blood substitutes) by UK general practitioners (GPs), anaesthetists, healthcare journalists and blood donors of both genders. A questionnaire survey was conducted from March – July 2000 involving (i) GPs (n = 88), (ii) anaesthetists (n = 143), (iii) journalists (n = 20), and (iv) blood donors (n = 250). Respondents rated (scale of 1–7) the general risk of blood transfusion and the risk of infection associated with blood transfusion and donation. Respondents were asked through free response questions to identify the risks they most associated with blood transfusion and the infections associated with blood transfusion and donation. They were also asked to indicate their preference for their own blood, compared to donor blood or a blood substitute and to make a choice between donated blood or a blood substitute. The percentage of respondents who preferred to receive their own blood, compared to donor blood or a suitable substitute, was 73–94%. When required to choose between donor blood or a blood substitute, there were significant (P < 0.05) differences between sample groups: anaesthetists and GPs preferred to receive a blood substitute (52–59%), whereas blood donors and journalists preferred donated blood (74–93%). These findings have clear implications for the future development and implementation of modern transfusion options, including the use and acceptability of blood substitutes as alternatives to donor blood.
A Comparison of Two Blood Bank Crossmatch Policies
Published in A I I E Transactions, 1971
The process of crossmatching blood is an integral part of blood bank operations. Human blood is specialized in the sense that one person's donated blood cannot be used randomly for another person. Before blood is infused to a patient, a test is performed to determine if the patient's blood matches the blood to be infused. Only blood that matches the patient's blood is acceptable. Two blood crossmatch policies are compared. The commonly used policy is compared to a modified policy and it is found that the latter can produce considerable savings in blood and concomitant costs. The absorbing Markov chain model is used to evaluate the two crossmatch policies.