Platelets are the smallest cells in the blood. They are formed in the bone-marrow and are important for the blood coagulation. Platelet tranfusions are given to patients propyhlactically before an operation but also in therapeutical purpose in connection with bleeding. It’s importent that the quality controls of the platelet concentrates are reliable. ADVIA®60 (Bayer HealthCare) is a fully automated cell counter which uses impedance principle to count platelets in blood samples. The purpose of the study was to evaluate this new instrument for use in the blood bank of Akademiska Sjukhuset in Uppsala. The instrument was bought to be used for quality control of platelet concentrates. 30 samples from platelet concentrates, from both apheresis and from buffy coats, were analyzed 10 times each on ADVIA®60 and the coefficient of variation (CV) was calculated for each sample. CV variated from 0,8 % to 2,9 % which is good considering that according to Bayer HealthCare the CV should be < 5 % for thrombocytes on ADVIA®60. The instrument was newly calibrated when the study was performed. Platelet count can also be performed by immunological or optical principles.

Controlling fates of stem and progenitor cells is one of the central goals of regenerative medicine. However, conventional cell enumeration methods are unable to distinguish between the effects of cell death, proliferation, and differentiation through molecular interventions on the output of specific cell types. We have devised a strategy to simultaneously obtain proliferation and death rates in cultures of highly purified erythroid progenitors. The approach is based on combining cell-surface marker analysis, cell-division tracking and 7-amino-actinomycin-D staining to monitor cell death. A compartment model of cell proliferation was developed to evaluate cell generation-specific length of cell-division, rates of entry into division, and cell death, from the experimental cell-division tracking data obtained following stimulation with erythropoietin (EPO) and Stem cell factor (SCF). The results indicated that EPO and SCF, either as single factor or in combination, differentially affect the rates of differentiation, length of cell-division and rates of death.

The ability to measure the oxygen saturation, oximetry, of retinal blood both non-invasively and in-vivo has been a goal of eye research for years. Retinal oximetry can in principle be achieved from the measurement of the reflectance spectrum of the ocular fundus. Oximetry calculations are however complicated by the scattering of red blood cells, the different pathways of light through blood and the ocular tissues that light interacts with before exiting the eye. The goal of this thesis was to investigate the influence of red blood cell scattering for different light paths relevant to retinal oximetry. Results of in-vitro whole blood experiments found calculated oxygen saturation differences between blood samples measured under different retinal light paths, and these differences did not depend on the absorbance path length. We also showed that the calculated oxygen saturation value determined by a multiple linear regression Beer-Lambert absorbance model depended on the wavelength range chosen for analysis. The wavelength dependency on the calculated oxygen saturation value is due in part to the correlation that exists between the oxyhaemoglobin and deoxyhaemoglobin extinction coefficient spectra and to errors in the assumptions built into the Beer-Lambert absorbance model. A wavelength region with low correlation between the oxyhaemoglobin and deoxyhaemoglobin extinction coefficients was found that is hypothesized to be a good range to calculate oxygen saturation using a multiple linear regression approach.

Thesis (Ph. D.)--University of Missouri-Columbia, 2000. / Typescript. Vita. Includes bibliographical references (leaves 113-117). Also available on the Internet.

Thesis (Ph. D.)--University of Missouri-Columbia, 2000. / Typescript. Vita. Includes bibliographical references (leaves 113-117). Also available on the Internet.

BACKGROUND: Exercise is a critical treatment modality in persons with Type II Diabetes Mellitus (T2DM), however people with this disease experience chronic fatigue and a decreased exercise capacity, which affects their ability or willingness to participate in physical activity. Studies suggest that this exercise intolerance may be partly due to a reduced exercising muscle blood flow (MBF), and in particular to a reduced ability of red blood cells (RBCs) to evoke ATP-mediated vasodilation and an increase in MBF as they traverse areas of high O2 demand. Additional evidence suggests that caffeine may attenuate this impairment by enhancing the release of ATP from RBCs. HYPOTHESIS: Persons with T2DM would have reduced Forearm Blood Flow (FBF), oxygen consumption (VO2), and exercise tolerance responses to exercise compared to control (CON) subjects, and caffeine would attenuate these impairments. METHODS: T2DM (n = 4) and CON (n = 4) participants performed rhythmic forearm handgrip exercise at an intensity equivalent to 17.5 kg until “task failure” or 20 minutes of exercise was reached, after having consumed either a caffeine (5mg/kg; Caff) or placebo (Pl) capsule. FBF (Doppler and Echo ultrasound of the brachial artery), VO2 and lactate efflux (deep venous blood sampling), forearm vascular conductance (FVK), mean arterial pressure (MAP) and heart rate (HR) were quantified for each minute of exercise. RESULTS: Steady state FBF was similar across groups and treatment conditions (mean ± SE ml/min; CONCaff 553.80 ± 82.35, CONPl 583.42 ± 112.62, T2DMCaff 523.33 ± 105.39, T2DMPl 569.08 ± 134.20, NS), and this was due to similar MAP and FVK (across groups and treatment conditions, NS). VO2 and Time to Task Failure (TTF) were not different between groups and treatment conditions (NS), although TTF tended to be improved with caffeine versus placebo (10.00 ± 2.02 vs 8.24 ± 1.79 min, P=0.295). There was a strong positive relationship between FBF and TTF (r2=0.763; P=0.005). CONCLUSIONS: In the exercise model utilized, persons with T2DM do not have impaired cardiovascular responsiveness or reduced exercise tolerance, and caffeine does not provide any benefit. Differences in exercising MBF may be an underlying mechanism regarding differences in exercise tolerance. / Thesis (Master, Kinesiology & Health Studies) -- Queen's University, 2009-09-16 16:19:42.537

Background: Dietary fat intake particularly of omega-3 and omega-6 fatty acids play an important role in growth and development and influence the risk of nutrition related non communicable diseases. These dietary intakes are reflected in the red blood cell (RBC) fatty acid profile. Aim: The aim of this study was to assess the fatty acid profile (%) of red blood cell membrane phospholipids in relation to the dietary intake of South African children aged 2 to 5 years, and of their mothers/caregivers from three communities, each with distinct dietary patterns. Method: In this cross-sectional observational study, approximately 105 children, aged: 2-5 years and their mother/caregivers were selected from three different geographical areas. These included; the urban community of De Aar (n=105), the urban coastal community Ocean View (n=93) and the rural community of Sekhukhune District (n=104). The red blood cell membrane total phospholipid fatty acid profile was determined by gas chromatography. A 24-hour dietary recall was done for each child and mother/caregiver as well as a socio-demographic questionnaire answered by each mother/caregiver. The mean and standard deviations of the RBC fatty acids were determined and compared through an analysis of variance (ANOVA) test followed by a Bonferroni post hoc test. Age and gender were controlled for in the children and age was controlled for in the mothers/caregivers. The median dietary intake (quartile range) was compared between communities by a Kruskal-Wallis test. The relationship between RBC membrane total phospholipid fatty acid profile and dietary fatty acid intake was done by stratifying the data for the three groups combined into tertiles according to RBC fatty acid profile and comparing the median (quartile range) of the dietary fatty acid intake in the different strata. Results: In the children, the total dietary fat, SFA and PUFA and omega-3 intake of De Aar (34.2%, 11.9%, 5.9% and 0.2% of energy, respectively) and Ocean View (33.0%, 11.2%, 7.4% and 0.2% of energy, respectively) was significantly different to Sekhukhune (19.9%, 6.5%, 3.0% and 0.1% of energy, respectively). Eicosaipentanoic (EPA) and docosahexaenoic (DHA) and α-linolenic acid (ALA) mean intake in children in all three sites was lower than recommended. In children from De Aar the RBC membrane total phospholipids contained significantly higher SFA and trans-fat percentages, while children in Sekhukhune District had significantly higher PUFA, omega-6 and omega-3 percentages. The linoleic acid (LA) profile in children from Ocean View was significantly higher than in those from De Aar and Sekhukhune District. The mother/caregivers’ dietary fat intake of total fat, SFA, PUFA and trans-fat was significantly higher in De Aar (31.7%, 10.5%, 6.3% and 0.2% of energy respectively) and Ocean View (37.4%, 12.1%, 8.5% and 0.59% of energy respectively) in comparison to Sekhukhune District (15.7%, 3.0%, 3.2% and 0.02% energy respectively). PUFA intakes were significantly higher in Ocean View (8.5% of energy). EPA, DHA and ALA dietary intakes were lower than recommended. The mother/caregiver’s RBC membrane total phospholipid SFA percentage was significantly higher in mothers/caregivers from De Aar and Ocean View whereas those from Sekhukhune District had significantly higher PUFA and omega-3 percentage. Conclusion: Differences particularly between the urban areas of De Aar and Ocean View and the rural area of Sekhukhune District were observed in dietary fat intake which was reflected in the red blood cell membrane total phospholipid fatty acid profile for children and mother/caregivers. Dietary omega-3 fatty acid intake was low in both children and mother/caregivers from all three study sites and is of concern. / MSc (Nutrition), North-West University, Potchefstroom Campus, 2014

Background: Dietary fat intake particularly of omega-3 and omega-6 fatty acids play an important role in growth and development and influence the risk of nutrition related non communicable diseases. These dietary intakes are reflected in the red blood cell (RBC) fatty acid profile. Aim: The aim of this study was to assess the fatty acid profile (%) of red blood cell membrane phospholipids in relation to the dietary intake of South African children aged 2 to 5 years, and of their mothers/caregivers from three communities, each with distinct dietary patterns. Method: In this cross-sectional observational study, approximately 105 children, aged: 2-5 years and their mother/caregivers were selected from three different geographical areas. These included; the urban community of De Aar (n=105), the urban coastal community Ocean View (n=93) and the rural community of Sekhukhune District (n=104). The red blood cell membrane total phospholipid fatty acid profile was determined by gas chromatography. A 24-hour dietary recall was done for each child and mother/caregiver as well as a socio-demographic questionnaire answered by each mother/caregiver. The mean and standard deviations of the RBC fatty acids were determined and compared through an analysis of variance (ANOVA) test followed by a Bonferroni post hoc test. Age and gender were controlled for in the children and age was controlled for in the mothers/caregivers. The median dietary intake (quartile range) was compared between communities by a Kruskal-Wallis test. The relationship between RBC membrane total phospholipid fatty acid profile and dietary fatty acid intake was done by stratifying the data for the three groups combined into tertiles according to RBC fatty acid profile and comparing the median (quartile range) of the dietary fatty acid intake in the different strata. Results: In the children, the total dietary fat, SFA and PUFA and omega-3 intake of De Aar (34.2%, 11.9%, 5.9% and 0.2% of energy, respectively) and Ocean View (33.0%, 11.2%, 7.4% and 0.2% of energy, respectively) was significantly different to Sekhukhune (19.9%, 6.5%, 3.0% and 0.1% of energy, respectively). Eicosaipentanoic (EPA) and docosahexaenoic (DHA) and α-linolenic acid (ALA) mean intake in children in all three sites was lower than recommended. In children from De Aar the RBC membrane total phospholipids contained significantly higher SFA and trans-fat percentages, while children in Sekhukhune District had significantly higher PUFA, omega-6 and omega-3 percentages. The linoleic acid (LA) profile in children from Ocean View was significantly higher than in those from De Aar and Sekhukhune District. The mother/caregivers’ dietary fat intake of total fat, SFA, PUFA and trans-fat was significantly higher in De Aar (31.7%, 10.5%, 6.3% and 0.2% of energy respectively) and Ocean View (37.4%, 12.1%, 8.5% and 0.59% of energy respectively) in comparison to Sekhukhune District (15.7%, 3.0%, 3.2% and 0.02% energy respectively). PUFA intakes were significantly higher in Ocean View (8.5% of energy). EPA, DHA and ALA dietary intakes were lower than recommended. The mother/caregiver’s RBC membrane total phospholipid SFA percentage was significantly higher in mothers/caregivers from De Aar and Ocean View whereas those from Sekhukhune District had significantly higher PUFA and omega-3 percentage. Conclusion: Differences particularly between the urban areas of De Aar and Ocean View and the rural area of Sekhukhune District were observed in dietary fat intake which was reflected in the red blood cell membrane total phospholipid fatty acid profile for children and mother/caregivers. Dietary omega-3 fatty acid intake was low in both children and mother/caregivers from all three study sites and is of concern. / MSc (Nutrition), North-West University, Potchefstroom Campus, 2014

The ability to measure the oxygen saturation, oximetry, of retinal blood both non-invasively and in-vivo has been a goal of eye research for years. Retinal oximetry can in principle be achieved from the measurement of the reflectance spectrum of the ocular fundus. Oximetry calculations are however complicated by the scattering of red blood cells, the different pathways of light through blood and the ocular tissues that light interacts with before exiting the eye. The goal of this thesis was to investigate the influence of red blood cell scattering for different light paths relevant to retinal oximetry. Results of in-vitro whole blood experiments found calculated oxygen saturation differences between blood samples measured under different retinal light paths, and these differences did not depend on the absorbance path length. We also showed that the calculated oxygen saturation value determined by a multiple linear regression Beer-Lambert absorbance model depended on the wavelength range chosen for analysis. The wavelength dependency on the calculated oxygen saturation value is due in part to the correlation that exists between the oxyhaemoglobin and deoxyhaemoglobin extinction coefficient spectra and to errors in the assumptions built into the Beer-Lambert absorbance model. A wavelength region with low correlation between the oxyhaemoglobin and deoxyhaemoglobin extinction coefficients was found that is hypothesized to be a good range to calculate oxygen saturation using a multiple linear regression approach.

Thesis (M.D. with Distinction in Research) -- University of Texas Southwestern Medical Center at Dallas, 2005. / Vita. Bibliography: 25-28.