Diurnal variation in serum glucose,pyruvate, lactate and lactate dehydrogenase levels under different environmental temperatures

Circadian rhythm of serum glucose, pyruvate, lactate and lactate dehydrogenase (LDH) was studied in normal healthy young volunteers at the onset (I Group, 7 cases) and peak (II Group, 8 cases) of winters in India with highly varied temperature. There was a significant difference, in the circadian rhythm of glucose, pyruvate and lactate dehydrogenase (LDH) of the two groups. A clockwise shift was observed in acrophase except in serum lactate, which is related to the energy demand in association with time qualified changes in diurnal activity of the individuals and change in photoperiod.     

A study of spectrin and lipid peroxidation of red blood cell membrane in thalassaemia carrier

The aim of the present work is to understand the lipid peroxidation of RBC membrane and the spectrin protein content of RBC membrane cytoskeleton of thalassaemic carrier state (trait) of β and hemoglobin E variant (HbE). We have measured the hemoglobin (Hb), malondialdehyde (MDA) and spectrin content of RBC membrane of thalassaemic carrier. The spectrin content (α and β band) of both β and HbE carrier was not changed than normal individuals. However, lipid peroxidation of RBC membrane was significantly increased in both β and HbE trait, and Hb level was also decreased in thalassaemic carrier. It may be assumed that oxidative damage by excess lipid peroxidation may have no role on irreversible membrane damage in β thalassaemia and HbE thalassaemia carrier.     

Reduced plasma ascorbic acid and red cell glutathione contents in sickle cell disease—A preliminary report

Glutathione and ascorbic acid in erythrocytes are suggested to be essential in the detoxification of superoxide radicals and hydrogen peroxide formed during red cell metabolism. In sickle cell patients who are more prone to haemolysis have greater propensity for the formation of superoxide radical and hydrogen peroxide. In the present study conducted on sickle cell patients provide evidence for the presence of reduced levels of both ascorbic acid and glutathione in the red cells. This may seem to suggest that vitamin C supplementation may help such patients who are prone to haemolysis.     

Pro-oxidant and anti-oxidant status in patients of sickle cell anaemia

The role of oxidant damage to red cells in sickle cell anaemia has been of interest in recent years. Although, available reports suggest that sickle cell erythrocytes are susceptible to endogenous free radical mediated oxidant damage there remains discrepancy in the status of antioxidant enzymes and antioxidant vitamins in these patients. In view of this, 107 cases of sickle cell anaemia (36 ‘SS’ and 71 ‘AS’ pattern—as confirmed by haemoglobin electrophoresis) were subjected to analysis of malondialdehyde, ascorbic acid, superoxide dismutase and albumin. The results were compared with 54 age and sex matched healthy controls. The results indicate a marked increase in lipid peroxidation and superoxide dismutase levels in both ‘SS’ and ‘AS’ types of sickle cell anaemia as compared to controls. Although no difference was observed in the levels of albumin in these groups the levels of ascorbic acid were significantly depleted in sickle cell anaemia patients. The results are indicative of enhanced lipid peroxidation along with imbalance in the pro-oxidant and antioxidant status in patients of sickle cell anaemia.     

学术型企业家特质及其创业行为与创业环境分析

本文从分析"学术型企业家"的本质着手,分析了"学术型企业家"的特质,阐述了"学术形企业家"兼备科学家创造力与企业家创新精神的特质,继而论述了学术型企业家的创业行为,分析了其特殊的创业环境。     

Effect of n-3 fatty acid supplementation on blood glucose, lipid profile and cytokines in humans: A pilot study

This study was undertaken to evaluate the effects of n-3 fatty acid supplementation on blood glucose, lipid profile and cytokines in humans. Twenty adult healthy subjects were supplemented with 1g/day fish oil concentrate capsules for 2 weeks. Fasting blood samples were taken at baseline and again after 2 week intervention. Fish oil supplementation significantly lowered fasting serum concentrations of total cholesterol, triacylglycerol, very low density lipoprotein and low density lipoprotein (P < 0.01). Also high density lipoprotein increased significantly compared with baseline value (P < 0.01). Fish oil did not significantly altere the fasting blood glucose concentration but significantly reduced the serum cytokines (P < 0.001). This study demonstrated that eicosapentanoic acid (EPA) and docosahexaenoic acid (DHA) supplementation altered serum lipids, lipoprotein and cytokine concentrations in normal human subjects even at the small dose of 660 mg of EPA plus DHA per day. It appears that EPA plus DHA can be a safe and perhaps beneficial supplement to inflammatory diseases.     

Frequency sweep rate dependence on the dielectrophoretic response of polystyrene beads and red blood cells

Alternating current (AC) dielectrophoresis (DEP) experiments for biological particles in microdevices are typically done at a fixed frequency. Reconstructing the DEP response curve from static frequency experiments is laborious, but essential to ascertain differences in dielectric properties of biological particles. Our lab explored the concept of sweeping the frequency as a function of time to rapidly determine the DEP response curve from fewer experiments. For the purpose of determining an ideal sweep rate, homogeneous 6.08 μm polystyrene (PS) beads were used as a model system. Translatability of the sweep rate approach to ∼7 μm red blood cells (RBC) was then verified. An Au/Ti quadrapole electrode microfluidic device was used to separately subject particles and cells to 10Vpp AC electric fields at frequencies ranging from 0.010 to 2.0 MHz over sweep rates from 0.00080 to 0.17 MHz/s. PS beads exhibited negative DEP assembly over the frequencies explored due to Maxwell-Wagner interfacial polarizations. Results demonstrate that frequency sweep rates must be slower than particle polarization timescales to achieve reliable incremental polarizations; sweep rates near 0.00080 MHz/s yielded DEP behaviors very consistent with static frequency DEP responses for both PS beads and RBCs.     

The effect of red blood cell aggregation on velocity and cell-depleted layer characteristics of blood in a bifurcating microchannel

Red blood cell (RBC) aggregation is a multifaceted phenomenon, and whether it is generally beneficial or deleterious remains unclear. In order to better understand its effect on microvascular blood flow, the phenomenon must be studied in complex geometries, as it is strongly dependent on time, flow, and geometry. The cell-depleted layer (CDL) which forms at the walls of microvessels has been observed to be enhanced by aggregation; however, details of the characteristics of the CDL in complex regions, such as bifurcations, require further investigation. In the present study, a microchannel with a T-junction was used to analyze the influence of aggregation on the flow field and the CDL. Micro-PIV using RBCs as tracers provided high resolution cell velocity data. CDL characteristics were measured from the same data using a newly developed technique based on motion detection. Skewed and sharpened velocity profiles in the daughter branches were observed, contrary to the behavior of a continuous Newtonian fluid. RBC aggregation was observed to increase the skewness, but decrease the sharpening, of the velocity profiles in the daughter branches. The CDL width was found to be significantly greater, with a wider distribution, in the presence of aggregation and the mean width increased proportionally with the reciprocal of the fraction of flow entering the daughter branch. Aggregation also significantly increased the roughness of the interface between the CDL and the RBC core. The present results provide further insight into how RBC aggregation may affect the flow in complex geometries, which is of importance in both understanding its functions invivo, and utilizing it as a tool in microfluidic devices.     

Simulation of malaria-infected red blood cells in microfluidic channels: Passage and blockage

Malaria-infected red blood cells (iRBCs) become less deformable with the progression of infection and tend to occlude microcapillaries. This process has been investigated in vitro using microfluidic channels. The objective of this paper is to provide a quantitative basis for interpreting the experimental observations of iRBC occlusion of microfluidic channels. Using a particle-based model for the iRBC, we simulate the traverse of iRBCs through a converging microfluidic channel and explore the progressive loss of cell deformability due to three factors: the stiffening of the membrane, the reduction of the cell''s surface-volume ratio, and the growing solid parasites inside the cell. When examined individually, each factor tends to hinder the passage of the iRBC and lengthen the transit time. Moreover, at sufficient magnitude, each may lead to obstruction of narrow microfluidic channels. We then integrate the three factors into a series of simulations that mimic the development of malaria infection through the ring, trophozoite, and schizont stages. These simulations successfully reproduce the experimental observation that with progression of infection, the iRBC transitions from passage to blockage in larger and larger channels. The numerical results suggest a scheme for quantifying iRBC rigidification through microfluidic measurements of the critical pressure required for passage.     

Biomechanical properties of red blood cells in health and disease towards microfluidics

Red blood cells (RBCs) possess a unique capacity for undergoing cellular deformation to navigate across various human microcirculation vessels, enabling them to pass through capillaries that are smaller than their diameter and to carry out their role as gas carriers between blood and tissues. Since there is growing evidence that red blood cell deformability is impaired in some pathological conditions, measurement of RBC deformability has been the focus of numerous studies over the past decades. Nevertheless, reports on healthy and pathological RBCs are currently limited and, in many cases, are not expressed in terms of well-defined cell membrane parameters such as elasticity and viscosity. Hence, it is often difficult to integrate these results into the basic understanding of RBC behaviour, as well as into clinical applications. The aim of this review is to summarize currently available reports on RBC deformability and to highlight its association with various human diseases such as hereditary disorders (e.g., spherocytosis, elliptocytosis, ovalocytosis, and stomatocytosis), metabolic disorders (e.g., diabetes, hypercholesterolemia, obesity), adenosine triphosphate-induced membrane changes, oxidative stress, and paroxysmal nocturnal hemoglobinuria. Microfluidic techniques have been identified as the key to develop state-of-the-art dynamic experimental models for elucidating the significance of RBC membrane alterations in pathological conditions and the role that such alterations play in the microvasculature flow dynamics.     

Asymmetry of red blood cell motions in a microchannel with a diverging and converging bifurcation

In microcirculation, red blood cells (RBCs) flowing through bifurcations may deform considerably due to combination of different phenomena that happen at the micro-scale level, such as: attraction effect, high shear, and extensional stress, all of which may influence the rheological properties and flow behavior of blood. Thus, it is important to investigate in detail the behavior of blood flow occurring at both bifurcations and confluences. In the present paper, by using a micro-PTV system, we investigated the variations of velocity profiles of two working fluids flowing through diverging and converging bifurcations, human red blood cells suspended in dextran 40 with about 14% of hematocrit level (14 Hct) and pure water seeded with fluorescent trace particles. All the measurements were performed in the center plane of rectangular microchannels using a constant flow rate of about 3.0 × 10⁻¹² m³/s. Moreover, the experimental data was compared with numerical results obtained for Newtonian incompressible fluid. The behavior of RBCs was asymmetric at the divergent and convergent side of the geometry, whereas the velocities of tracer particles suspended in pure water were symmetric and well described by numerical simulation. The formation of a red cell-depleted zone immediately downstream of the apex of the converging bifurcation was observed and its effect on velocity profiles of RBCs flow has been investigated. Conversely, a cell-depleted region was not formed around the apex of the diverging bifurcation and as a result the adhesion of RBCs to the wall surface was enhanced in this region.     

Influence of aerobic treadmill exercise on blood glucose homeostasis in noninsulin dependent diabetes mellitus patients

The role of treadmill exercise on blood glucose homeostasis in noninsulin dependent diabetes mellitus (NIDDM) were studied using males between age of 45 and 60 years (X-52), who were clinically and biochemically-confirmed cases of NIDDM were taken into study group. Control group comprised of 10 males between age group of 45 to 60 (X-53) years. All the subjects were assessed by physician and were investigated to confirm diabetic status. The whole study period was extended for 6 weeks. The significant decrease in postprandial blood sugar (44.4 mg% for the study group and 32.2mg% for the control group) with a significant inter group difference (P<0.05) was observed. The mean decrease in fasting blood sugar (39.4mg% for the study group and 27.4mg% for the control group), with a marginal inter group difference (P<0.05) was observed. The treadmill exercise was found to be a definite tool in addition to drug and diet in glycemic control.     

Influence of pranayamas and yoga-asanas on serum insulin,blood glucose and lipid profile in type 2 diabetes

A distinguishable feature of type 2 diabetes besides hyperglycemia and deranged lipid profile is an impaired insulin secretion, peripheral insulin resistance and obesity which has become a major health concern worldwide. India with an estimated 31million diabetics in 2000 and 79mllions by the yr 2030 has the highest number of type 2 diabetics in the world. In this study, we aimed to see if yoga-asanas and pranayamas have any influence in modifying certain biochemical parameters. Sixty patients of uncomplicated type 2 diabetes (age 35–60 yrs of 1–10 yrs duration) were divided into two groups: Group 1 (n=30): performed yoga along with the conventional hypoglycemic medicines and group 2 (n=30): patients who only received conventional medicines. Duration of the study was 45 days. Basal recordings of blood glucose (fasting and post-prandial), lipid profile and serum insulin were taken at the time of recruitment and the second reading after forty five days. Results showed a significant improvement in all the biochemical parameters in group 1 while group 2 showed significant improvement in only few parameters, thus suggesting a beneficial effect of yoga regimen on these parameters in diabetic patients.     

A numerical study on the dynamics of droplet formation in a microfluidic double T-junction

In this study, droplet formations in microfluidic double T-junctions (MFDTD) are investigated based on a two-dimensional numerical model with volume of fluid method. Parametric ranges for generating alternating droplet formation (ADF) are identified. A physical background responsible for the ADF is suggested by analyzing the dynamical stability of flow system. Since the phase discrepancy between dispersed flows is mainly caused by non-symmetrical breaking of merging droplet, merging regime becomes the alternating regime at appropriate conditions. In addition, the effects of channel geometries on droplet formation are studied in terms of relative channel width. The predicted results show that the ADF region is shifted toward lower capillary numbers when channel width ratio is less than unity. The alternating droplet size increases with the increase of channel width ratio. When this ratio reaches unity, alternating droplets can be formed at very high water fraction (wf = 0.8). The droplet formation in MFDTD depends significantly on the viscosity ratio, and the droplet size in ADF decreases with the increase of the viscosity ratio. The understanding of underlying physics of the ADF phenomenon is useful for many applications, including nanoparticle synthesis with different concentrations, hydrogel bead generation, and cell transplantation in biomedical therapy.     

Migration and vascular lumen formation of endothelial cells in cancer cell spheroids of various sizes

We developed a microfluidic device to culture cellular spheroids of controlled sizes and suitable for live cell imaging by selective plane illumination microscopy (SPIM). We cocultured human umbilical vein endothelial cells (HUVECs) within the spheroids formed by hepatocellular carcinoma cells, and studied the distributions of the HUVECs over time. We observed that the migration of HUVECs depended on the size of spheroids. In the spheroids of ∼200 μm diameters, HUVECs migrated outwards to the edges within 48 h; while in the spheroids of ∼250 μm diameters, there was no outward migration of the HUVECs up to 72 h. In addition, we studied the effects of pro-angiogenic factors, namely, vascular endothelial growth factor (VEGF) and fibroblast growth factor (β-FGF), on the migration of HUVECs in the carcinoma cell spheroid. The outward migration of HUVECs in 200 μm spheroids was hindered by the treatment with VEGF and β-FGF. Moreover, some of the HUVECs formed hollow lumen within 72 h under VEGF and β-FGF treatment. The combination of SPIM and microfluidic devices gives high resolution in both spatial and temporal domains. The observation of HUVECs in spheroids provides us insight on tumor vascularization, an ideal disease model for drug screening and fundamental studies.     

我国R&D枢纽形成区域选择及发展模式研究

从省域尺度上考察我国R＆D枢纽的形成与发展状况。采用2006年我国各省市R＆D活动的数据,建立R＆D枢纽选择指标体系,从研发投入、研发产出、研发产业化和创新环境方面对我国R＆D枢纽形成区域及发展模式进行实证研究。研究结果表明：北京和上海适宜成为我国的R＆D枢纽。在R＆D枢纽的发展模式上,北京适合发展成混合型的研发枢纽,上海适合发展成为自主创新型的研发枢纽。     

Paired values of serum fructosamine and blood glucose for the screening of gestational diabetes mellitus: A retrospective study of 165 Saudi pregnant women

This study reports the utilization of serum fructosamine and blood glucose for the screening of gestational diabetes mellitus (GDM). Blood samples from 165 pregnant women were analyzed for fasting blood glucose (FBG), random blood glucose (RBG) and serum fructosamine. The actual fructosamine levels were corrected for serum protein (c-Fruct) for more precise presentation. Two cut-off values of FBG (>5.3 mmol/L and >7.0 mmol/L) and RBG (>7.8 mmol/L and >11.0 mmol/L) were used to classify hyperglycemic subjects for subsequent evaluation. The average values±standard deviations for FBG, RBG and cFruct were 5.865±1.95, 7.767±3.21 and 2.387±0.47 mmol/L, respectively. FBG levels were significantly correlated with RBG (Pearson correlation=0.597, P<0.001). Significant correlations were also observed between cFruct and FBG (Pearson correlation=0.673, P<0.001) or RBG (Pearson correlation=0.641, P<0.001). Out of 165 subjects, 24 (14.5%) cases were classified as hyperglycemic on the basis of FBG>7.0 mmol/L or RBG>11.0 mmol/L; use of lower cut-off values resulted higher frequencies of hyperglycemia. Whereas, a combined criteria of FBG>5.3 mmol/L and cFruct >2.5 mmol/L predicted 35 patients as the most probable hyperglycemic as compared to 32 patients identified using the criteria of RBG >7.8 mmol/L and cFruct >2.5 mmol/L. These criteria were associated with 4.8% and 3.6% false-positivity at the expense of 3.6% and 3.0% false-negative outcomes, respectively. The levels of FBG, RBG and cFruct were significantly higher in hyperglycemic groups (irrespective of grouping criteria) as compared to the respective normal groups. In conclusion, these findings clearly indicate that the paired values of cFruct with FBG or RBG could help in filtering high-risk individuals for OGTT and therefore avoiding a unnecessary OGTT.     

大企业衍生创业对创业集群形成的影响研究

提出"大企业衍生创业"的概念,并构建以创业能力形成为中心环节的衍生创业的过程模型;在文献分析基础上通过定性分析并辅以案例验证,认为大企业衍生创业是产业相关企业不断创建产生并最终推动集群形成的重要动因;建立以大企业衍生创业为核心的集群形成解释模型,并据此提出通过创业-集群的方法来促进区域经济成长和创新发展的政策建议。     

国际创业韧性形成与成长机理案例研究

企业在国际市场上面临极大的不确定性、复杂性和风险性,现有研究多关注企业如何进行国际创业以取得成功,鲜有学者探究企业如何应对国际市场中的挫折或失败并持续进行国际创业。对金鹏的国际创业过程进行探索性单案例分析得出：(1)国际市场上的情境不确定性与网络关系触发组织能力、危机意识和应对机制进一步演化而形成国际创业韧性;(2)在国际创业中持续的学习和经验积累,以及国际创业团队面对失败或成功时的态度和行为推动国际创业韧性成长,并经过以能力为主导、以信心为主导和以应对机制为主导三个阶段。最后明晰国际创业韧性成长机理,以指导企业形成和培养动态化的国际创业韧性。