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Biomedical subjects

S Balasubramanian

Publications and source records attributed to S Balasubramanian.

At least 19 recordsLinked to original sources
PubMed2007

Differential gene expression patterns in porcine nuclear transfer embryos reconstructed with fetal fibroblasts and mesenchymal stem cells.

The present study compared the developmental ability and gene expression pattern at 4-cell, 8-cell, morula, and blastocyst stages of porcine nuclear transfer (NT) embryos from fetal fibroblasts (FFs) and mesenchymal stem cells (MSCs), in vitro fertilized (IVF), and in vivo derived embryos. MSC-NT embryos showed enhanced blastocyst formation, higher total cell number, and a low incidence of apoptosis compared to FF-NT embryos. Alterations in the expression pattern of genes implicated in transcription and pluripotency (Oct4, Stat3, Nanog), DNA methylation (Dnmt1, Dnmt3a), histone deacetylation (Hdac2), growth factor signaling, and imprinting (Igf2, Igf2r) and apoptosis (Bax, Bcl2) regulation were observed in NT embryos. The expression of transcripts in MSC-NT embryos more closely followed that of the in vivo derived embryos compared with FF-NT embryos. In conclusion, MSCs with a relatively undifferentiated genome might serve as suitable donors that could be more efficiently reprogrammed to re-activate expression of early embryonic genes in porcine NT.

Analysis of Variance↗
PubMed2007

Cellular composition and viability of cloned bovine embryos using exogene-transfected somatic cells.

The present study compared the efficiency of transgenic (TG) cloned embryo production by somatic cell nuclear transfer (SCNT) with fetal-derived fibroblast cells (FFCs) which were transfected with pEGFP-N1 to in vitro-fertilized (IVF), parthenogenetic and SCNT counterparts by evaluating the rates of cleavage and blastocyst formation, apoptosis rate at different developmental stages, cell number, ploidy and gene expression in blastocysts. In SCNT and TG embryos, the rates of cleavage and blastocyst formation were significantly lower (p < 0.05) than those of IVF controls, but it did not differ between SCNT and TG embryos. In IVF control, 86.7% embryos displayed diploid chromosomal complements and the rates were significantly (p < 0.05) higher than those of SCNT and TG embryos. Most TG embryos (79%) with FFCs expressed the gene by both PCR and under fluorescence microscopy. The expression of apoptosis by TUNEL was first detected at six to eight cell stages in all embryos of IVF, SCNT and TG groups, but the expression rate at each developmental stages was significantly higher (p < 0.05) in SCNT and TG embryos than in IVF counterparts. The expression rate in inner cell mass (ICM) of TG embryos was significantly higher (p < 0.05) than in SCNT and IVF embryos. These results indicate that the high occurrence of apoptosis observed in SCNT and TG embryos compared with IVF counterparts might influence the developmental competence. Moreover, the SCNT embryos derived using non-transfected donor cells exhibited a lower apoptosis expression in ICM cells than in TG embryos derived using pEGP-N1-transfected donor cells suggesting a possible role of negative gene effect in TG embryos.

Animals↗
PubMed2006

The surface structure of ionic liquids: comparing simulations with x-ray measurements.

The surface-normal electron density profile of an ionic liquid, [bmim][PF6], derived from x-ray reflectivity measurements, is compared with two independent molecular-dynamics simulations. It is shown that a meaningful comparison requires a detailed accounting for both thermal and nonthermal surface roughening effects. The former is due to thermally excited capillary waves, and the latter is due to the molecular zero-point motion and form. These quantities influence very significantly, but differently, the simulated and measured density profiles. Stripping off these effects from both types of profiles yields the intrinsic structure factor of the surface. The simulated intrinsic structure factors are found to deviate considerably from the measured one. The introduction of additional ad hoc surface roughness to the simulated profiles greatly reduces the deviation, however, no physical origin for this effect can be identified. The method employed in this study should prove useful for simulation-experiment comparisons of other liquid surfaces, provided they obey capillary-wave theory, as do almost all liquid surfaces studied to date by x-ray reflectivity.

Journal Article↗
PubMed2006

Layering at an ionic liquid-vapor interface: a molecular dynamics simulation study of [bmim][PF6].

The structure of the planar liquid-vapor interface of a room-temperature ionic liquid, 1-n-butyl-3-methylimidazolium hexafluorophosphate ([bmim][PF6]), is studied using atomistic molecular dynamics simulations. Layering of the ions at the interface is observed as oscillations in the corresponding number density profiles. These oscillations, however, are diminished in amplitude in the electron density profile, due to a near cancellation in the contributions from the anions and the cations. An enhancement by 12% in the electron density at the interface over its value in the bulk liquid is observed, in excellent agreement with X-ray reflectivity experiments. The anions are found to predominantly contribute to this increase in the interfacial electron density. The cations present at the interface are oriented anisotropically. Their butyl chains are observed to be preferentially oriented along the interface normal and to project outside the liquid surface, thus imparting a hydrophobic character. In the densest region of the interface, the imidazolium ring plane is found to lie parallel to the surface normal, in agreement with direct recoil spectroscopy experiments.

Journal Article↗
PubMed2006

Ultra-structural changes and developmental potential of porcine oocytes following vitrification.

This study evaluated the effects of exposure and/or vitrification of porcine metaphase II (MII) oocytes on their in vitro viability and ultra-structural changes with two experiments. Experiment 1 examined the effect of vitrified oocytes on microtubule localization, mitochondrial morphology, chromosome organization and the developmental rate in IVF control and vitrified oocytes. Oocytes matured for 44 h were subjected to IVF (IVF control). Oocytes matured for 42 h were exposed to cryoprotectants (CPA control), followed by 2h culture, and subjected to IVF. Oocytes vitrified at 42 h post-maturation were warmed, cultured for 2h, and subjected to IVF (vitrified). Experiment 2 evaluated the effect of oocytes freezing on development of ICSI with and without activation and parthenotes. Fresh and vitrified oocytes were subjected to ICSI with and without electrical activation. Cleavage and blastocyst rates were significantly (P<0.05) lower in vitrified IVF, parthenote and ICSI embryos than those in fresh counterparts. Between ICSI embryos from fresh oocytes and vitrified oocytes, the rates of blastocyst were significantly higher (P<0.05) in activated group than the group without activation. Significant differences (P<0.05) were observed in normal spindle configuration of vitrified (43.5%) compared to control (81.0%) oocytes, but no significant difference was observed between CPA exposed and control groups. In conclusion, porcine oocytes at MII stage are very sensitive to vitrification with altered microtubule localization and mitochondrial organization thus resulting in impaired fertilization and embryo development.

Animals↗
PubMed2006

The interferon-induced GTPase, mGBP-2, confers resistance to paclitaxel-induced cytotoxicity without inhibiting multinucleation.

Interferon (IFN) exposure promotes a wide variety of cellular changes, many of which are still poorly characterized. Many of these changes are initiated through the induction or repression of hundreds of genes. One multigene family of GTPases induced by both type I and type II IFNs is the Guanylate Binding Protein (GBP) family. In this study we show that a murine GBP, mGBP-2, confers resistance to a microtubule-stabilizing drug used in cancer therapy, paclitaxel. Paclitaxel-treated, mGBP-2-expressing NIH 3T3 cells showed less rounding and substrate detachment than treated control cells. mGBP-2 also conferred resistance to paclitaxel-induced cytotoxicity at paclitaxel concentrations from 0.005 to 15 microM. mGBP-2-mediated paclitaxel resistance did not protect against the generation of multinucleate cells but fewer of these cells progressed to apoptosis.

Animals↗
PubMed2006

DNA methylation levels in porcine fetal fibroblasts induced by an inhibitor of methylation, 5-azacytidine.

Removal of the somatic DNA methylation pattern from donor cells and remodeling of embryonic status have been suggested as integral processes for successful nuclear transfer (NT) reprogramming. This study has investigated the effects of 5-azacytidine (5-azaC), a DNA methylation inhibitor, on global methylation changes in porcine fetal fibroblasts (PFF); this may improve NT attributable to the potential reprogramming of the methyl groups. PFF in 5th passage cultures were treated with 0, 0.5, 1.0, 2.0, and 3.0 microM 5-azaC for 96 h; 5-azaC inhibited the growth at all tested concentrations. At the higher concentrations of 5-azaC used, cells appeared to exhibit morphological changes and to become apoptotic as observed by TUNEL assay. Thus, cells were negatively affected by 5-azaC. Differences in cellular ploidy were also observed at higher concentrations. Analysis showed no considerable changes in the proportion of cells at the G1-phase of the cell cycle with 5-azaC concentrations. The fractional part of the methylated DNA of these cells was significantly reduced by 5-azaC treatment. Confocal microscopy confirmed the inhibition of methylation levels in PFF with increased concentrations of 5-azaC. Exposure to 5-azaC altered the expression of genes involved in imprinting (IGF2) or pro-apoptosis (BAX), whereas there was a reduction in the expression of the main enzyme responsible for replicating the DNA methylation pattern (DNMT1) and anti-apoptosis (BCL2L1). Therefore, 5-azaC induces a relative reduction in methylation in PFF, and cells treated with 0.5 microM 5-azaC may have enhanced potential for porcine NT.

Animals↗
PubMed2006

Effect of cysteamine supplementation of in vitro matured bovine oocytes on chilling sensitivity and development of embryos.

In vitro techniques for production of bovine embryos including in vitro oocyte maturation (IVM), fertilization (IVF) and culture (IVC) are becoming increasingly employed for a variety of research purposes. However, decreased viability following cryopreservation by conventional methods has limited commercial applications of these technologies. A practical alternative to facilitate transport would be to arrest development by chilling without freezing. The present research was undertaken to evaluate chilling sensitivity of IVM-IVF embryos at different stages of development, and to determine possible beneficial effects of cysteamine treatment during IVM, previously shown to enhance embryo development in culture, on survival following chilling at different stages. Embryos produced by standard IVM-IVF-IVC methods were chilled to 0 degrees C for 30 min at 2-cell (30-34 h post-insemination, hpi), 8-cell (48-52 hpi) or blastocyst (166-170 hpi) stages. Viability after chilling was assessed by IVC with development to expanded blastocyst stage determined on days 7 and 8 post-insemination (pi) and hatching blastocyst stage determined on days 9 and 10 pi. Control embryos at the same stages were handled similarly, but without chilling, and development during culture similarly assessed. The effect of cysteamine supplementation (100 microM) of the IVM medium was determined for both chilled and non-chilled (control) embryos. Cysteamine supplementation during IVM had no significant effect on oocyte maturation or fertilization, but increased the proportions of oocytes developing to blastocyst stage by day 7 (13.7+/-0.9% versus 7.2+/-0.9%; P<0.05), total blastocysts (20.5+/-0.9% versus 15.3+/-1.3%; P<0.05), and hatching blastocysts (16.8+/-1.6% versus 12.0+/-1.5%; P<0.05). The greater survival in terms of hatching (78.6+/-7.0) following chilling of blastocysts produced by IVM-IVF of oocytes matured in media supplemented with cysteamine offers promise for applications requiring short-term storage to facilitate transport of in vitro produced bovine embryos.

Animals↗
PubMed2006

Effect of chilling on the development of in vitro produced bovine embryos at various cleavage stages.

PURPOSE: Bovine embryos and zygotes are known to be sensitive to "temperature shock" when cooled to temperatures near 0 degrees Celsius. The effect of chilling on in vitro derived embryos at various cleavage stages was investigated. METHODS: Cumulus-oocyte-complexes (COCs) were matured in IVM medium with serum. Presumptive zygotes were cultured in serum free in vitro culture (IVC) medium. Embryos were used as chilled or control samples at the 2-cell, 4-cell, 8-cell, morula, and blastocyst stages. Embryos in 0.2 mL PBS in plastic straws were cooled rapidly in ethanol baths at 0 degrees Celsius for 30 min. Embryo viability was assessed by in vitro development. RESULTS: The percentage of control embryos that hatched as blastocysts increased the later stage at which they were selected. Relative proportion of embryos increased from 28% to 48% to 68% when chilled at the 8-cell, morula or blastocyst stages. CONCLUSIONS: IVF-produced embryos are differentially susceptible to cooling injury. Cell counts made of those blastocysts formed from chilled embryos indicated subtle effects of chilling.

Animals↗
PubMed2006

Somatic cell nuclear transfer in buffalos: effect of the fusion and activation protocols and embryo culture system on preimplantation embryo development.

The present study was conducted primarily to evaluate several factors that affect the nuclear transfer programme in water buffalos, in which relatively few studies have been performed. Embryos reconstructed with quiescent fetal fibroblasts and metaphase II cytoplasts were matured for 24 h, and activation was found to be comparatively better than in those matured for 30 h. A significantly higher proportion of embryos fused (52.0 +/- 1.9) and cleaved (51.2 +/- 1.7) when the couplets were fused 4-6 h before activation than when fused and activated simultaneously (46.5 +/- 1.6 and 44.5 +/- 2.0, respectively). Development of nuclear transfer embryos to the blastocyst stage (4.8 +/- 2.2) was supported by a commercially available sequential medium, and cleavage (76.5 +/- 2.8) was significantly higher in this medium compared with cleavage in TCM-199 with oviduct epithelial cell coculture (45.6 +/- 1.5) and synthetic oviduct fluid (21.8 +/- 6.6). Of the 16 cloned embryos transferred, none resulted in pregnancy. The present study demonstrates that optimal numbers of cloned buffalo blastocysts can be obtained from oocytes matured for 24 h, fused 3-4 h before activation and cultured in a commercially available sequential media (G1/G2), thus providing further information to enable successful nuclear transfer in buffalos.

Animals↗
PubMed2006

Influence of seasons, extenders, slow and rapid freezing on seminal characters in Korean native bucks.

The success of AI technology is based on both semen quality and freezing process. In order to establish the semen freezing techniques in Korean native bucks, factors affecting the success were evaluated in the present study. Semen collected by electro-ejaculation from bucks during four distinct seasons was evaluated for semen volume and pH, sperm motility and survivability. The semen volume, concentration and total cell were higher in spring, summer and less in winter. Yet, there were no seasonal differences in the proportional data of live sperm, motility score and pH of semen among seasons. The percentage of live sperm after thawing was found to increase with increased concentration of lactose in Tris-Egg yolk-glycerol (TY-G), being highest in TY-G supplemented with 180 mm lactose (TYL180-G), but did not differ between TY-G and TYL120-G. Sperm motility was enhanced by employing 2.0 h equilibration time with rapid freezing method. In conclusion, semen could be frozen with high success rates for further use of AI in breeding techniques and to preserve the Korean native bucks.

Animals↗
PubMed2006

Reference values for oxygen saturation by pulse oximetry in healthy children at sea level in Chennai.

UNLABELLED: There is little information on oxygen saturation (SaO2) values in children in developing countries. AIM: To determine the reference values for oxygen saturation by pulse oximetry in healthy children living at sea level in Chennai and aged between 1 mth and 5 yrs. DESIGN AND SETTING: A prospective study was conducted in Kanchi Kamakoti CHILDS Trust Hospital from February to May 2005. METHODS: A total of 626 healthy children aged between 1 mth and 5 yrs were examined for heart rate, respiratory rate and SaO2. RESULTS: The mean SaO2 levels for children in the age groups 1-3 mths, 3 mths to 1 yr, 1-3 years and 3-5 years were 98.5%, 98.8%, 98.9% and 99.1%, respectively. The overall mean and median SaO(2) values for the children in the different age groups were 99%. The mean -2 SD values of oxygen saturation in the age groups were 96.5%, 96.4%, 96.3% and 97.1%, respectively, with an overall mean of 96.6%. CONCLUSION: The reference value for mean SaO2 in healthy children aged between 1 mth and 5 yrs and living at sea level in Chennai city was 98.5% or more, but the -2SD values had a mean of 96.6%.

Aging↗
PubMed2006

Hypocalcemia due to vitamin D deficiency in exclusively breastfed infants.

This report is based on observations during the conduct of a study of hypocalcemia in infants and children. In a study of 50 cases, 13 exclusively breast fed infants manifesting with hypocalcemic seizures were confirmed to have vitamin D deficiency. None of the 13 infants had received vitamin D supplementation. All of them had biochemical evidence of hyperparathyroidism and low levels of 25 (OH) Vit D3 and promptly responded to therapy with vitamin D and calcium. All the mothers of these 13 infants had low levels of 25 (OH) Vit D3. Mothers of 5 infants had reported reduced exposure to sunlight due to religious reasons. This report emphasizes the need to supplement Vitamin D in exclusively breast fed infants and also to encourage exposure to sunlight in them and their mothers.

Breast Feeding↗
PubMed2006

A reappraisal of the criteria to diagnose plasma leakage in dengue hemorrhagic fever.

A study was undertaken to analyze the usefulness of radiographic and ultrasonographic findings and area specific hematocrit cut off values in Dengue Hemorrhagic Fever (DHF). Of the 65 cases, 35 were DHF and 30 were Dengue Fever as per the WHO case definition. Among the DHF cases, hemoconcentration (>20%) was detected in 20 cases (57.14%), hypoproteinemia in 11 (31.42%) and clinical evidence of pleural effusion and or ascites in 25 (71.42%). Hemoconcentration based on area specific hematocrit cut off values was observed in 32 cases (91.42%). Ultrasonographic evidence of plasma leakage was seen in 32 cases (91.42%). In detecting plasma leakage, area specific hematocrit cut off values and ultrasonography had the highest sensitivity (91.42%), while ultrasonography had the highest negative predictive value of 84.21%. Clinical evidence of plasma leakage was more frequent than hemoconcentration or hypoproteinuria. Ultrasonography is an ideal non-invasive investigation to detect plasma leakage and area specific hematocrit values are useful as evidence of plasma leakage.

Adolescent↗
PubMed2005

Synthesis and in vitro microbiological evaluation of imidazo(4,5-b)pyridinylethoxypiperidones.

A series of imidazo(4,5-b)pyridinylethoxypiperidones was designed, synthesized and characterized for evaluation of potential antibacterial activity against Bacillus subtilis, Klebsiella pneumoniae, Escherichia coli, Staphylococcus aureus and Pseudomonas aeruginosa and antifungal activity against Candida albicans-6, Candida albicans, Aspergillus niger, Candida albicans-51 and Aspergillus flavus. Structure-activity relationship led to the conclusion that compound 39 exerted strong in vitro antibacterial activity against Bacillus subtilis and Staphylococcus aureus whereas compounds 38 and 39 displayed promising antifungal activity against Aspergillus flavus. The interesting antimicrobial profile of compound 39 led us to select this derivative for further development.

Animals↗
PubMed2005

Dynamics in a room-temperature ionic liquid: a computer simulation study of 1,3-dimethylimidazolium chloride.

The transport properties and solvation dynamics of model 1,3-dialkylimidazolium chloride melt at 425 K is studied using molecular-dynamics simulations. Long trajectories of a large system have been generated and quantities such as the self-diffusion coefficient of ions, shear viscosity, and ionic conductivity have been calculated. Interestingly, the diffusion of the heavier cation is found to be faster than the anion, in agreement with experiment. The interaction model is found to predict a higher viscosity and lower electrical conductivity compared to experimental estimates. Analysis of the latter calculations points to correlated ion motions in this melt. The solvation time correlation function for dipolar and ionic probes studied using equilibrium simulations exhibits three time components, which include an ultrafast (subpicosecond) part as well as one with a time constant of around 150 ps. The ultrafast solvent relaxation is ascribed to the rattling of anions in their cage, while the slow component could be related to the reorientation of the cations as well as to ion diffusion.

Journal Article↗
PubMed2005

Development of cloned pig embryos by nuclear transfer following different activation treatments.

This study compared the effects of activation treatments on the development and ploidy of nuclear transferred (NT) pig embryos. After in vitro maturation of oocytes collected from the slaughterhouse, oocytes were enucleated and reconstructed by transfer of donor cells and fusion with three DC pulses (1.4 kV/cm, 20 musec). Oocytes were pulsed thrice electrically with 1.4 kV/cm for 20 musec and NT eggs were divided into three treatment groups: Group 1 (no further treatment), Group 2 (10 mug/mL cycloheximide [CHX], 3 hr), and Group 3 (1.9 mM 6-dimethylaminopurine [DMAP], 3 hr). All the eggs were cultured in sets of 30 in 60 muL drops of NCSU-23 supplemented with 4 mg/mL fatty acid free BSA, and compared for the rates of development and ploidy. The rates of cleavage, development, and total cell number of parthenotes in Group 3 were significantly (P < 0.05) higher than those in Groups 1 and 2. Cleavage rates of NT embryos in Group 1 were significantly (P < 0.05) lower than those in Groups 2 and 3 (73% vs. 81% and 82%, respectively). Development into blastocyst stage and total cell number of NT embryos in Group 3 were significantly (P < 0.05) higher than those in Groups 1 and 2. Although the embryos in Group 3 had higher development, approximately 58% of NT embryos evaluated were abnormal ploidy (6% haploidy, 9% polyploidy, and 42% mixoploid). The results suggested that although DMAP enhanced development and higher cell number, due attention should be paid to abnormal ploidy in pig NT embryos.

Analysis of Variance↗