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B Kiran

Publications and source records attributed to B Kiran.

11 recordsLinked to original sources
PubMed2005

Peritransplant and long-term secretion of interleukin-1beta in cyclosporine treated syngeneic rats allografted with islets of langerhans.

Interleukin-1beta (IL-1beta) is one of the proinflammatory cytokines that may mediate primary nonfunction of islets of Langerhans, limiting the success of allogeneic transplantation. The aim of this study was to assess differences between the secretion of IL-1beta as well as glycemia in peri- and long-term periods of intraportal islet allo-transplantation with or without cyclosporine (CyA) immunosuppression. Inbred Wistar albino rats were transplanted intraportally with rat islets isolated by collagenase digestion. The two recipient groups (6 rats/group) were: group 1, control, islet transplantation (ITX) without any treatment and group 2, CyA-treated via the femoral muscle on days -1, 0, +1, and +2. Serum IL-1beta (pg/mL) levels were measured by ELISA on days 0 (pre-ITX), +1, +2, and +195. Tail vein blood was used to evaluate glycemia (mg/dL). No major differences were observed in IL-1beta secretion on days 0, +1, or +195 between the groups. Immunosuppressive treatment produced significantly lower secretion in group 2 (P < .002) on day +2. Significantly greater secretions were detected at days +195, +1, and +195 compared to days 0, +2, and +2, respectively (P < .002; P < .008; P < .002). Positive correlations were observed between IL-1beta levels on days +1 and +2 (r = 0.845, P < .034). The mean values in groups 1 and 2 on days 0, +1, and +2 were 140.6 +/- 4.62 vs 119.1 +/- 12.12, 73.1 +/- 19.59 vs 88.3 +/- 14.08, 106.5 +/- 13.79 vs 92.5 +/- 15.8, respectively. No animal in group 1 displayed glycemia while three group 2 animals did at day +195. However, a negative correlation was found between IL-1beta on day 0 and glycemia on day +195 (r = -0.999, P < .026). Our results suggest that IL-1beta secretion, which is detrimental for islet engraftment, decreases at peritransplant day +2, but is upregulated during long-term graft survival both in controls and in CyA-treated recipients.

Animals↗
PubMed2004

Ab initio study of small graphitic cones with triangle, square, and pentagon apex.

Accurate geometries of carbon nanocones of different sizes with a triangle, square or pentagon at the apex have been determined for the first time using a quantum chemical optimization method. The structure close to the apex is distorted from an ideal conical surface. The charging effect of the central defect is quite different from that predicted by tight-binding calculations. The symmetry behavior of the frontier orbitals and the size of the highest occupied molecular orbital-lowest unoccupied molecular orbital gap versus cone type and size is explained. The density of states quickly converges towards that of graphite when the size of the cone increases. In comparison to previous results in the literature it is found that the local densities of states of cones, that are locally different but belong to the same topo-combinatoric class, share common features.

Journal Article↗
PubMed2004

Effects of pneumoperitoneum created through CO2 insufflation and parameters of mechanical ventilation (PEEP application) on systemic dissemination of intraabdominal infections.

BACKGROUND: To examine whether CO2 pneumoperitoneum and positive end expiratory pressure (PEEP) in mechanical ventilation affect the systemic spread of intraabdominal infection. METHODS: Sprague-Dawley male rats weighing 200-300 g were allocated to three groups of 12 animals in each. All rats received mechanical ventilation under general anesthesia. An intraabdominal infection model was established by injecting with 1 ml of Escherichia coli (10(9) CFU/mL) intraperitoneally. Half of the animals in each group were exposed to PEEP (10 cmH2O). CO2 pneumoperitoneum at 13 mmHg was applied to the rats in group 1. Group 2 rats underwent laparotomy. Group 3 served as controls. In addition, TNF-alpha serum levels were measured at baseline and 3 h. A peritoneal specimen for histopathological examination were obtained after the rats were killed at the end of 3 h. For the assessment of data, descriptive statistical methods (mean, standard deviation) as well as Friedman test for repeated measurements in multiple groups, Kruskal-Wallis test for intergroup comparisons, Dunn's multiple comparison test for subgroup comparisons, Mann-Whitney U test for comparisons between paired groups, chi-square and Fisher's exact test for comparison of qualitative data, and McNemar's test for assessment of changes in group variables over time were used. The results were considered statistically significant if probability (p) values were <0.05. RESULTS: Grades of peritonitis in group 1 and 2 were seen to differ nonsignificantly. In group 1, baseline blood cultures were not included in the assessment between the subgroups that received PEEP or not, as there was no growth in any of the subgroups. No significant difference was detected between growth in blood cultures at 1, 2, and 3 h ( p > 0.05). Application of PEEP in subgroups did not alter the blood culture results ( p > 0.05). Significant differences were seen between the initial and final TNF-alpha values of groups (KW: 18.94, p < 0.0001). The values in control group were observed to be significantly lower than those in groups 1 and 2 ( p < 0.01, p < 0.001). Bacteremia and systemic spread of the intraabdominal infection did appear to be different according to the PEEP application. After the assessments of ventilation parameters in our study, significant reductions in pH and HCO3 levels were detected in group 1 as a result of pneumoperitoneum, which was consistent with the literature. There is a significant difference between pH values at baseline and at the end of 1 h because of pneumoperitoneum (Fr: 10.01, p < 0.05). PEEP application in subgroups did not create significant differences in terms of respiratory parameters ( p < 0.01). CONCLUSION: No difference was found between the applications of CO2 pneumoperitoneum and laparotomy with regard to bacteremia and infection-induced peritonitis. It was determined that pneumoperitoneum along with PEEP application had neither a positive nor a negative impact on intraabdominal infection.

Animals↗
PubMed2004

Effect of human somatotropin hormone on cultured rat islets.

Because growth hormone (GH) improves the insulin secretion capacity of isolated human fetal islets in vitro, we sought to show that it positively influences isolated rat islets. Islets isolated from Wistar albino rats by a modified automated system were cultured in media containing 87% RPMI 1640, 10% FCS, 2% antibiotic-antimycotic, and 1% L-glutamine for 12 +/- 2 days. The cultured islets were divided into two groups: growth hormone negative (Group I) and growth hormone positive (Group II). On the 5th day we observed a decrease in the islet cell counts in both groups (Group I 28% versus Group II 45%). On the 10th day, the decrease continued in the GH-negative group (59%), while the count remained stable in the GH-positive group. The viability of rat islets was determined by fluorescein diacetate (FDA) plus propidium iodide (PI) staining. In comparison to the peripheral green, central orange-red staining pattern of Group I islets upon fluorescent microscopy, Group II showed more compact islets. Cultured islets seemed to be brighter than those without GH in the cultured islets. In conclusion, we observed that 2 weeks of incubation in the presence of GH acts positively on cultured rat islets for both their amount and their viability.

Animals↗
PubMed2000

Which electron count rules are needed for four-center three-dimensional aromaticity?

A series of charged and neutral four-center n-electron (4c-ne, n = 1-4) molecules based on the adamantane framework, but which include combinations of boron, nitrogen, and phosphorus atoms at bridgehead positions, were studied computationally at the B3LYP/6-31G* level of density functional theory (DFT). The three-dimensional aromaticity, observed earlier for the 1,3,5,7-bisdehydroadamantane dication (1), is found to be general for 4c-2e electron systems. The degree of electron delocalization, evaluated by energetic, geometric, and various magnetic criteria, is quite independent of the molecular symmetry (point groups vary from Td to Cs), the degeneracy of the orbitals, the molecular charges, and the nature of the atoms participating in the delocalized bonding. Although the multiple positive (e.g., in 1 and some of the heteroatom systems) and multiple negative charges are strongly repulsive, the rigid adamantane frameworks help hold the bridgehead atoms within bonding distances with the fewer available electrons. The corresponding 4c-1e doublets are approximately half as aromatic as the 4c-2e singlets based on the same criteria. However, the three-electron systems may either adopt distorted but still four-center delocalized structures, or alternative 3c-2e two-dimensional arrangements in which the fourth bridgehead atom is more distant. There is no need to derive special rules for each point group for 4c-ne systems. Although the three-dimensional stabilization is computed to be quite appreciable, ranging between 10 and 50 kcalmol(-1), this delocalization energy is generally not sufficient to overcome distortion due to strain in higher homologues of 1 and in analogous noncage systems. Among the various 4c-2e homoadamantanedehydro dications studied, only the 1,8-dehydrohomoadamandiyl-3,6-dication forms a three-dimensional aromatic system.

Journal Article↗
PubMed2000

Are oxocarbon dianions aromatic?

Assessment of the cyclic electron delocalization of the oxocarbon dianions, C(n)()O(n)()(2)(-) and their neutral counterparts C(n)()O(n)() (n = 3-6), by means of structural, energetic, and magnetic criteria, shows that C(3)O(3)(2)(-) is doubly aromatic (both sigma and pi cyclic electron delocalization), C(4)O(4)(2)(-) is moderately aromatic, but C(5)O(5)(2)(-), as well as C(6)O(6)(2)(-), are less so. Localized orbital contributions, computed by the individual gauge for localized orbitals method (IGLO), to the nucleus-independent chemical shifts (NICS) allow pi effects to be disected from the sigma single bonds and other influences. The C-C(pi) contribution to (NICS(0,pi) (i.e., at the center of the ring) in oxocarbon dianions decreases with ring size but shows little ring size effect at points 1.0 A above the ring. On the basis of the same criteria, C(4)O(4) exhibits cyclic electron delocalization due to partial occupancy of the sigma CC bonds. However, the dissociation energies of all the neutral oxocarbons, C(n)()O(n)(), are highly exothermic.

Journal Article↗