Biomedical subjects

K Nageswari

Publications and source records attributed to K Nageswari.

9 recordsLinked to original sources

PubMed2002

Quantitative assessment of cerebral neocapillary network and its remodeling in mice using intravital fluorescence videomicroscopy.

To assess the responses of different growth factors on cerebral neocapillary density (NCD), cerebral angiogenesis was induced in mice using growth factors, basic fibroblast growth factor (bFGF) and platelet-derived growth factor (PDGF) at a concentration of 6 ng/ml each. Intravital fluorescence videomicroscopy was used to quantitatively evaluate microhemodynamic parameters such as diameter and red cell velocity. The gel-nylon mesh-sandwich system was implanted over the exposed cortex. After incubation for different periods of time (days 7, 14 or 28), fluorescein isothiocyanate (FITC)-labeled red cells were injected through a carotid artery and the neocapillaries on the upper surface of the nylon mesh were observed under a fluorescence videomicroscope. Based on the recorded videoimages, we evaluated the density, diameter and red cell velocity of the neocapillaries. The NCD in the bFGF group on day 7 was significantly higher than that in the PDGF group on day 7 (P < 0.01). The NCD (index) reached 100% on day 14, while it reduced significantly in both the groups on day 28. The neocapillary diameter was greater than that of the pre-existing capillaries on day 7. On day 14, a clear difference appeared in the capillary density between large and small vessels. The red cell velocity increased with the number of days after incubation. The response of cerebral neocapillaries to acetylcholine was measured after 28 days of incubation with growth factor bFGF and with PDGF. The red cell velocity increased significantly from its basal value in the PDGF group. These results suggest that the neocapillaries in the PDGF group matured earlier than those in the bFGF group.

Acetylcholine↗

PubMed2000

Effects of exercise on rheological and microcirculatory parameters.

The physiological changes occurring during exercise and its possible consequences have been receiving considerable attention lately. In this paper, we studied the changes in hemorheological and microcirculatory parameters, before and after the exercise, in the subjects undergoing mild exercise (n = 20). A cycle ergometer adjusted at 2.5 kilopounds was used for 15 minutes. The whole blood viscosity showed a significant increase after exercise at all shear rates (0.512-51.2/s) except at the high shear rate (94.5/s). However, the significant level was more (P < 0.005) at low shear rates (0.512-4.39/s). A significant elevation in plasma viscosity was observed after the exercise (P < 0.0008). Red cell rigidity showed a significant increase after the exercise (P < 0.001) while red cell aggregation and hematocrit failed to show any significant change. Microcirculatory studies showed a significant increase in the basal perfusion level after exercise (P < 0.0002) when compared to the resting state value. There was a significant decrease in reactive hyperaemia perfusion index after exercise (P < 0.0007). Hence, it is evident from this study that short-term exercise significantly alters hemorheological and microcirculatory parameters.

Adult↗

PubMed2000

Microcirculatory characterization of cerebral angiogenesis in mice using intravital videomicroscopy.

The present study investigated microcirculatory characteristics of the cerebral neovasculature induced in mice, using basic fibroblast growth factor (bFGF) and platelet derived growth factor (PDGF). The nylon-mesh sandwich (collagen gel/growth factor in bovine serum albumin embedded in between two nylon-mesh pieces) was used to induce angiogenesis. After different days of incubation, the observations of neocapillaries were done on the upper surface of the nylon-mesh, using fluorescence video-microscopy. The neocapillary diameter, red cell velocity, and the neocapillary density were evaluated based on the video-image. The neocapillaries were visible on the upper surface of the mesh on the 6th day after the incubation, and red cells started to flow from the day 7. The neocapillary red cell velocity increased with days after incubation, but its level was less than that of the pre-existing capillaries. The neocapillary diameter decreased as the neocapillaries got matured. The neocapillary density was dependent on the doses of bFGF and PDGF. The neocapillary diameter did not alter with the higher concentration as well as with different growth factors. Both bFGF and PDGF showed an increase in red cell velocity at high concentration.

Animals↗

PubMed1999

Effect of saturated, omega-3 and omega-6 polyunsaturated fatty acids on myocardial infarction.

Dietary fatty acids have cholesterol lowering, antiatherogenic, and antiarrhythmic properties that decrease the risk of myocardial infarction (MI). This study was designed to study the effects of various oils rich in either polyunsaturated (omega-3 or omega-6) fatty acids (PUFA) or saturated fatty acids (SFA) on the severity of experimentally induced MI. Male albino Sprague-Dawley rats (100-150 g; n = 20) were fed diets enriched with fish oil (omega-3 PUFA), peanut oil (omega-6 PUFA), or coconut oil (SFA) for 60 days. Experimental MI was induced with isoproterenol. Mortality rates; serum enzymes aspartate amino transferase; alanine amino transferase; creatine phosphokinase (CPK); lipid profiles in serum, myocardium, and aorta; peroxide levels in heart and aorta; activities of catalase and superoxide dismutase; and levels of glutathione were measured. The results demonstrated that mortality rate, CPK levels, myocardial lipid peroxides, and glutathione levels were decreased in the omega-3 PUFA treated group. Maximum increase in parameters indicative of myocardial damage was seen in the coconut oil group. These findings suggest that dietary omega-3 PUFA offers maximum protection in experimentally induced MI in comparison to omega-6 PUFA and SFA enriched diets. SFA was found to have the least protective effect.

Journal Article↗

PubMed1998

Hemorheological parameters for biocompatibility evaluation.

Biomaterials have been extensively used for various clinical applications. Since blood is very sensitive to the presence of any foreign substances, testing for hemocompatibility is a major part of biocompatibility evaluation. At present, blood viscosity parameters are being used as screening tests for biomaterial compatibility. Successful use of these parameters will help eliminate many incompatible materials from being subjected to extensive testing. In this study, we evaluated the blood viscosity parameters (n = 10)--whole blood viscosity, plasma viscosity, red cell rigidity, hematocrit, and biochemical parameters (total proteins and albumin). A significant increase in hemorheological parameters after incubation with material was found to be an indicator of incompatibility.

Adult↗

PubMed1998

Hemorheological changes in blood transfusion-treated beta thalassemia major patients.

Beta thalassemia major is an inherited impairment of haemoglobin structure, in which there is partial or complete failure to synthesize a specific type of globin chain. The study was undertaken to assess the hemorheological changes in beta thalassemic major patients. We studied hemorheological parameters in thalassemic patients (n = 37) immediately after blood transfusion. The parameters studied were whole blood viscosity (WBV), plasma viscosity (PV), red cell rigidity (RCR) and hematocrit (Hct). Blood samples from age-and sex-matched normal controls were also analysed for comparison. Statistical analysis was done using Student's t-test and p values were recorded. The results showed a significant decrease in level of WBV and Hct in patients when compared to normal controls. However, the red cell rigidity was higher when compared to normal controls. Increase in RCR should show an increase in WBV. But in our study cases there was a significant decrease in WBV which was probably due to the significant decrease in level of hematocrit.

Blood Transfusion↗

PubMed1998

Hemorheological changes in nephrotic syndrome.

Hemorheological parameters of childhood nephrotic syndrome cases, in relapse and remission (n = 60 in each group), were studied and their results were compared with those of an equal number of age and sex matched normal children free from any renal disease. During relapse, it was noticed that the viscosity parameters, viz. plasma viscosity, red cell rigidity and whole blood viscosity, were deranged when compared to the values obtained in the remission period. These observations were statistically analyzed using t-test with the level of significance p = 0.05. It was also noted that serum/plasma biochemistry played an important role with regards to the fluidity of blood. During relapse period, fibrinogen level was significantly high, which persisted at a high level even during remission when compared to normal controls. The high cholesterol and triglyceride levels during relapse were responsible for a high plasma viscosity, increased red cell rigidity and thereby contributed directly to a marked increase in whole blood viscosity. Total protein and albumin levels were significantly decreased during relapse when compared to remission period. Hence, hemorheological parameters can be used for early detection of cases prone to relapse and could be of prognostic significance.

Blood Viscosity↗

PubMed1997

Hematological aspects of biocompatibility--review article.

The development and improvement of medical devices and artificial organs is critically dependent on the realisation of the importance of the interactions between materials and body tissues. In this regard, the evaluation of biocompatibility assumes paramount importance. This paper reviews the hematological aspects of biocompatibility--the responses evoked by the material as well as the methods for their detection. The paper also mentions a few methods of improvement of material compatibility.

Animals↗

PubMedDate not supplied

Association of hemorheological parameters and risk of stroke in hypertensives of Indian origin.

The blood viscosity parameters of one hundred and fifty cases of WHO grade I and II hypertension of Indian origin, on treatment with calcium antagonists, were measured and a six-monthly follow up was conducted for a period of three years. The whole blood viscosity (WBV), plasma viscosity (PV), red cell rigidity (RG) and hematocrit (Hct) were monitored. Occurrence of stroke was considered as the outcome variable and it was observed that sixteen cases of stroke occurred during the follow up period (10.7% incidence). After excluding known risk factors of age, sex, addictions, blood pressure levels, cholesterol levels and underlying diseases, it was observed that an increased whole blood viscosity > 6 centiPoise was associated with an increased risk of stroke (Relative risk 2.9, 95% confidence interval 2.2 to 3.7). An increased red cell rigidity in a hypertensive patient was found to be an independent risk factor for stroke. Patients with red cell rigidity greater than 4 had 4 times (Relative risk 3.6, 95% confidence interval 3.2 to 4) higher risk of stroke as compared with patients with red cell rigidity levels less than 4. Treatment with drugs modifying the rheological profile and aiming at improving the red cell deformability should thus be considered in hypertensive patients in an attempt to prevent the occurrence of stroke.

Blood Viscosity↗