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Biomedical subjects

V Srivastava

Publications and source records attributed to V Srivastava.

At least 19 recordsLinked to original sources
PubMed2005

Fludarabine-based conditioning for allogeneic stem cell transplantation for multiply transfused patients with Fanconi's anemia.

A fludarabine-based protocol (fludarabine (25 mg/m(2)/day x 6 days), cyclophosphamide (10 mg/kg/day x 2 days) and ATG (ATGAM 10 mg/kg/day x 4 days)) was used in four multiply transfused Fanconi's anemia (FA) patients aged 5-15 years to reduce rejection during allogeneic bone marrow transplantation (BMT). Graft-versus-host disease (GVHD) prophylaxis consisted of cyclosporine and mini methotrexate. The graft source was G-CSF-stimulated bone marrow or peripheral blood stem cells (PBSC) in two patients each. All patients engrafted with median time to ANC>500/mm(3) being 14 days (range: 12-17) and unsupported platelet count >20 ,000/mm(3) being 13 days (range: 11-18). One patient had secondary graft rejection on day 56 and expired on day 69 due to fungal pneumonia. One patient who developed acute myeloid leukemia on day 56 underwent successful induction with cytosine and daunorubicin followed by peripheral blood stem cell (PBSC) rescue on day 70 and is presently in remission with complete donor chimerism and grade I GVHD. At a median follow-up of 13 months (range: 4-21), three patients (75%) are well with complete donor chimerism. Addition of fludarabine to the conditioning regimen for BMT in FA can provide additional immunosuppression for engraftment without increasing toxicity.

Adolescent↗
PubMed2004

BIAS: Bioinformatics Integrated Application Software.

MOTIVATION: We introduce a development platform especially tailored to Bioinformatics research and software development. BIAS (Bioinformatics Integrated Application Software) provides the tools necessary for carrying out integrative Bioinformatics research requiring multiple datasets and analysis tools. It follows an object-relational strategy for providing persistent objects, allows third-party tools to be easily incorporated within the system and supports standards and data-exchange protocols common to Bioinformatics. AVAILABILITY: BIAS is an OpenSource project and is freely available to all interested users at http://www.mcb.mcgill.ca/~bias/. This website also contains a paper containing a more detailed description of BIAS and a sample implementation of a Bayesian network approach for the simultaneous prediction of gene regulation events and of mRNA expression from combinations of gene regulation events. CONTACT: hallett@mcb.mcgill.ca.

Computational Biology↗
PubMed2003

Actions of ethanol on epidermal growth factor receptor activated luteinizing hormone secretion.

OBJECTIVE: Activation of the epidermal growth factor receptor (EGF-R) stimulates prepubertal luteinizing hormone-releasing hormone (LHRH) release, which in turn induces luteinizing hormone (LH) secretion. Although ethanol (ETOH) diminishes LHRH secretion and delays the onset of female puberty, its actions following EGF-R activation are unknown. We therefore investigated the effects of ETOH on EGF-induced LHRH and LH release, both in vivo and in vitro. METHOD: Basal blood samples were taken every 15 minutes from immature female rats, which then received ETOH (3 g/kg) or saline by gastric gavage. After a 90-minute ETOH absorption period, a single blood sample was drawn from each rat. Finally, EGF (200 ng/3 microl) was injected into the third ventricle of all animals and postinjection samples were drawn every 15 minutes. A similar experimental design was performed except no blood samples were taken. After ETOH exposure, EGF was administered, and 45 minutes later the animals were killed and their medial basal hypothalamus and pituitary were removed and analyzed for EGF-R and cyclooxygenase (COX) 1 and 2 by western blot analysis. For in vitro experiment, median eminence fragments from immature female rats were exposed to ETOH in a static incubation system, and prostaglandin-E, (PGE2) and LHRH were measured. RESULTS: EGF stimulated LH release, and this release was blunted (p < .05) by ETOH. Western blot analysis revealed that ETOH did not alter the EGF-R protein levels in the hypothalamus. ETOH blocked EGF-induced PGE2 and LHRH released from isolated median eminences. EGF administration increased both COX-1 (p < .001) and COX-2 (p < .01), but both enzymes were blocked by ETOH. CONCLUSIONS: The ETOH-induced decrease in EGF-stimulated LH release is due to a reduction in the formation of hypothalamic PGE2 and, subsequently, suppressed LHRH release.

Age Factors↗
PubMed2001

Single-copy primary transformants of maize obtained through the co-introduction of a recombinase-expressing construct.

We describe a variation of the method to generate single-copy transgenic plants by recombinase-mediated resolution of multiple insertions. In this study, a transgene construct flanked by oppositely oriented lox sites was co-bombarded into maize cells along with a cre-expressing construct. From analysis of the regenerated plants, a high percentage of the primary transformants harbored a single copy of the introduced transgene, and among these, a majority also lacked the cre construct. We deduce that the expression of cre must have contributed to resolving concatemeric molecules either prior to or after DNA integration into the maize genome.

Gene Dosage↗
PubMed2001

Tuberculosis among allogeneic bone marrow transplant recipients in India.

Allogeneic bone marrow transplant recipients have severe impairment of cell-mediated immunity and hence a higher incidence of mycobacterial infections might be expected in regions where tuberculosis is common. We reviewed the case records of 217 patients who underwent allogeneic bone marrow transplantation during the period 1986-1999 at our center in India. Mycobacterial infections were diagnosed in three patients (1.38%). All patients presented with extrapulmonary disease. Two patients had disseminated tuberculosis with one of these being diagnosed on autopsy studies. The third patient had tuberculosis involving the cervical lymph node and dorsal spine. Two patients treated with antituberculous therapy are well. Infection with Mycobacterium tuberculosis is not a common problem in allogeneic bone marrow recipients even in an endemic area, but when it occurs, it is usually disseminated with predominantly extrapulmonary involvement.

Adult↗
PubMed2001

Do cellulose binding domains increase substrate accessibility?

This article provides an overview of various theories proposed during the past five decades to describe the enzymatic hydrolysis of cellulose highlighting the major shifts that these theories have undergone. It also describes the effect of the cellulose-binding domain (CBD) of an exoglucanase/xylanase from bacterium Cellulomonas fimi on the enzymatic hydrolysis of Avicel. Pretreatment of Avicel with CBDCex at 4 and 37 degrees C as well as simultaneous addition of CBDCex to the hydrolytic enzyme (Celluclast, Novo, Nordisk) reduced the initial rate of hydrolysis owing to irreversible binding of CBD proteins to the substrate's binding sites. Nonetheless, near complete hydrolysis was achieved even in the presence of CBDCex. Protease treatment of both pure and CBDCex-treated Avicel reduced the substrates' hydrolyzability, perhaps owing to proteolysis of the hydrolyzing enzyme (Celluclast) by the residual Proteinase K remaining in the substrate. Better protocols for complete removal of CBD proteins from the substrate need to be developed to investigate the effect of CBD adsorption on cellulose digestibility.

Binding Sites↗
PubMed2000

Spectral analysis of vibrational harmonic motion by use of a continuous-wave CO2 Doppler lidar.

Vibrational motion of a harmonic oscillator was investigated with a focused continuous-wave (cw) CO2 Doppler lidar at 9.1-microm wavelength. A continuum of frequencies along with many discrete, equally spaced, resonant frequency modes was observed. The frequency modes are similar in structure to the oscillatory longitudinal modes of a laser cavity and arise because of interference of the natural resonant frequency of the oscillator with specific frequencies within the continuum. Each consecutive resonant frequency mode occurred for a movement of the oscillator much less than the wavelength of incident lidar radiation. For vigorous vibration of the oscillator, the observed spectra may be indicating nonlinear motion.

Journal Article↗
PubMed1999

Single-copy transgenic wheat generated through the resolution of complex integration patterns.

Genetic transformation of plants often results in multiple copies of the introduced DNA at a single locus. To ensure that only a single copy of a foreign gene resides in the plant genome, we used a strategy based on site-specific recombination. The transformation vector consists of a transgene flanked by recombination sites in an inverted orientation. Regardless of the number of copies integrated between the outermost transgenes, recombination between the outermost sites resolves the integrated molecules into a single copy. An example of this strategy has been demonstrated with wheat transformation, where four of four multiple-copy loci were resolved successfully into single-copy transgenes.

Chimera↗
PubMed1999

Effects of ethanol on leptin secretion and the leptin-induced luteinizing hormone (LH) release from late juvenile female rats.

BACKGROUND: Chronic ethanol (EtOH) exposure lowers serum insulin-like growth factor-1 (IGF-1) and luteinizing hormone (LH) levels and also delays female puberty, similar to the deficits in the reproductive system that occur during leptin deficiency. Leptin administration restores fertility and gonadotropin secretion in the ob/ob mouse and can induce recovery of reproductive function in food-restricted animals. This study assessed the effects of EtOH on serum leptin levels, and whether exogenous leptin administration could restore IGF-1 and LH levels in the EtOH-treated animals. METHODS: In the first study, 29-day-old female rats were divided into control and EtOH-treated groups, each of which received their respective diet regimen for 5 consecutive days. The EtOH-treated animals were subdivided and received an intraperitoneal injection of either leptin (100 microg/0.1 ml) or saline twice daily. Control animals also received intraperitoneal saline injections twice daily. On day 34, animals were killed, and serum leptin, LH, and IGF-1 were measured by RIA. In a second study we assessed the acute effects of a single 3 g/kg dose of EtOH on the ability of leptin to act centrally to induce LH release. For this, leptin (1 microg) was administered via a third ventricular (3V) cannula and blood sampling via jugular cannula. In a third experiment, animals were again subjected to a chronic feeding regimen. When 34 days old, they were killed and the anterior pituitaries removed and incubated in a static incubation system for 60 min to establish basal LH release, then for an additional 60 min in medium containing leptin (10(-7) M). RESULTS: Chronic EtOH exposure lowered serum leptin (p < 0.01), IGF-1 (p < 0.01), and LH (p < 0.05) levels. Leptin administration to EtOH-treated animals did not restore serum IGF-1 levels. This peptide did, however, effectively restore LH levels to normal, but did not advance the timing of puberty. Acute EtOH administration was found to block leptin-induced LH release following central administration of the peptide. Conversely, anterior pituitaries from control and 5-day EtOH-treated animals that were incubated in vitro released (p < 0.01) equal amounts of LH in response to leptin (10(-7) M). CONCLUSIONS: These data demonstrate that EtOH administration not only can suppress peripheral levels of leptin, but also blocks its central action to facilitate LH secretion. Although replacement of leptin can reverse the EtOH-induced suppression of LH by a direct action at the level of the pituitary, it cannot elevate serum IGF-1; a peripheral signal that acts centrally to stimulate LH releasing-hormone (LHRH)/LH release during the juvenile-peripubertal transition period, and thus accelerates the initiation of female puberty. These results demonstrate further the complex actions and interactions of multiple hormones involved in the pubertal process and the vulnerability of their actions to the toxic effects of EtOH.

Age Factors↗
PubMed1998

Ethanol blocks the central action of IGF-1 to induce luteinizing hormone secretion in the prepubertal female rat.

Insulin-like growth factor-1 (IGF-1) is emerging as a signal of peripheral origin capable of acting centrally to induce luteinizing hormone (LH) secretion and accelerate the initiation of female puberty. Since we have shown previously that ethanol (ETOH) can suppress prepubertal LH release and delay female puberty, we hypothesized that these detrimental effects might be due, at least in part, to the drugs ability to alter the central actions of IGF-1. Thus, we have investigated the effects of ETOH on IGF-1 induced LH release in vivo, and on IGF-1 induced prostaglandin-E2 (PGE2) and LH-releasing hormone (LHRH) release in vitro from rats during the juvenile phase of development as well as from rats during the early stage of first proestrus. For the in vivo experiment three initial jugular blood samples were taken at 10-min. intervals from all rats, then the animals received either a 3g/Kg dose of ETOH or an equal volume of saline by gastric gavage. The rats were subsequently left undisturbed for 90 min. to allow time for ETOH absorption, then a single blood sample was drawn from each rat. Finally, IGF-1 (200 ng/3 microl) was microinjected into the third ventricle of all animals and five more blood samples were withdrawn at 10 min. intervals. We demonstrated that IGF-1 induced the release of LH (p<0.01) in the saline controls from rats in both phases of pubertal development. Conversely, this effect of IGF-1 was blocked by ETOH in both developmental groups. For the in vitro experiment, median eminences (MEs) were dissected, then incubated in the presence or absence of ETOH (50 mM). The amount of PGE2 and LHRH released was measured from the same samples following the addition of IGF-1 (100 ng/ml). As above, similar responses were observed from rats in both developmental phases. IGF-1 stimulated the release of PGE2 (p<0.001) and LHRH (p<0.01) from the incubated nerve terminals in the absence of ETOH; however, these effects were blocked by the presence of ETOH. Thus, these combined in vivo and in vitro results suggest that ETOH can acutely block IGF-1 induced LH release during the juvenile-peripubertal transition period, and that this is a centrally mediated action which is due to the diminished formation of PGE2 resulting in decreased LHRH release.

Animals↗
PubMed1998

Alcohol's effects on female puberty: the role of insulin-like growth factor 1.

Research suggests that alcohol consumption during early adolescence may delay the onset of female puberty. Alcohol's effect on sexual development is associated with altered function of insulin-like growth factor 1 (IGF-1). This hormone, which is produced in the liver, travels through the bloodstream to the brain, where it helps coordinate overall physical growth with the maturation of the reproductive system. Long-term alcohol consumption inhibits the production of IGF-1 in the liver. Short-term alcohol administration alters IGF-1 function within the brain, ultimately suppressing the release of specific reproductive hormones that initiate puberty. Large proportions of young girls develop drinking habits that place them at risk for alcohol-related endocrine disorders at a crucial time in female pubertal development.

Alcohol Drinking↗
PubMed1998

Recall of old and recent information.

A neural network model for 'forgetting upon learning' is developed in such a way that old information can also be evoked. A new synaptic clipping scheme coupled with selective reinforcement of information is introduced that mimics the learning and memory functions of the 'limbic system' in the brain. The model thus enables both long-term (old) and short-term (recent) memories to exist concurrently, without one affecting the other, as one expects in a realistic situation.

Humans↗
PubMed1997

Ovarian nitric oxide synthase (NOS) gene expression during peripubertal development.

Nitric oxide (NO) is generated from L-arginine by different isoforms of the enzyme nitric oxide synthase (NOS) and is known to be involved in mediating several biological functions, some of which are associated with reproduction. In this study, we examined the ability of the prepubertal ovary to express the inducible (i), as well as the neuronal-type constitutive (c) form of NOS and also, investigated whether either isoform undergoes changes in the ovary during peripubertal development. Results indicate that both forms of NOS were expressed in the ovary and that the iNOS mRNA transcripts were expressed without being exogenously induced. When compared with juvenile levels, iNOS, but not cNOS, mRNA increased (p<0.01) during the early proestrous phase of development. By the late proestrous phase, the levels of iNOS mRNA declined markedly (p<0.001) and remained low throughout both the first estrous and diestrous phases. Western blot analysis revealed both iNOS and cNOS protein expression in each phase of puberty with only iNOS showing a significant change during the peripubertal period. Specifically, there was an initial increase in the expression of iNOS protein during the late proestrous phase (p<0.05) which was accompanied by preovulatory increases in serum estradiol (p<0.01) and LH (p<0.001). The iNOS protein levels then dramatically increased to peak on the morning of first estrus (p<0.001), an event associated with declining (p<0.05) serum levels of estradiol. These data demonstrate developmental changes in the expression of ovarian iNOS mRNA and protein both before and after first ovulation; hence, suggesting a role for NO in the ovary during pubertal maturation and furthermore, providing compelling evidence at the gene level supporting the hypothesis that the NO/NOS system plays a physiological role in ovarian function.

Animals↗
PubMed1996

An accessory protein enhances both DNA binding and activity of DNA polymerase alpha isolated from normal, but not transformed, human fibroblasts.

DNA polymerase alpha/primase (pol alpha) isolated from fibroblasts established from a 66-year-old human donor (GM3529) exhibited decreased specific activity compared with pol alpha from either fetal-derived fibroblasts (WI38), or pSV3.neo-transformed GM3529 fibroblasts. The pol alpha specific activity decrease was correlated with a decreased proliferative capacity frequently seen in cells from aged donors. Pol alpha isolated from pSV3.neo-transformed GM3529 cells (GM3529T) exhibited a single isoform with about 10-fold higher specific activity than pol alpha from GM3529 cells. GM3529T pol alpha was immunoreactive with both anti-pol alpha and anti-SV40 large tumor antigen. Polymerases from GM3529 and GM3529T cells were treated with a pol alpha accessory protein, alpha AP, isolated from L1210 cells. Pol alpha from GM3529T cells showed no increase in activity in the presence of alpha AP, while pol alpha isolated from GM3529 cells exhibited about an 8-fold increase in activity after treatment with alpha AP. Double stranded SV40 DNA containing multiple ori sequences exhibited a greater decrease in electrophoretic mobility in the presence of GM3529T pol alpha than when treated with GM3529 pol alpha. In the presence of pol alpha from either GM35229 or GM3529T cells SV40 dsDNA exhibited a decrease in electrophoretic mobility, and in each instance addition of alpha AP resulted in an even greater decrease in DNA mobility. These data indicate that alpha AP increased pol alpha binding to SV40 dsDNA, or that alpha AP bound the DNA in addition to previously bound pol alpha. GM3529 pol alpha also bound non-specific, non-SV40, dsDNA, whereas GM3529T pol alpha with associated TAg did not bind the non-viral dsDNA unless alpha AP was added to the preparation. While not all human diploid fibroblast cell lines derived from aged human donors necessarily exhibit decreased proliferative capacity compared with cells from young donors, decreased specific activity associated with a decline in cellular DNA synthesis is typical of pol alpha from cells derived from aged human donors. We suggest that a decrease in endogenous alpha AP interaction with pol alpha may account, in part, for the loss of DNA binding affinity and specific activity of pol alpha from GM3529 cells derived from an aged donor.

Aged↗
PubMed1996

Integration and expression of the high-molecular-weight glutenin subunit 1Ax1 gene into wheat.

The unique bread-making characteristic of wheat flour is closely related to the elasticity and extensibility of the gluten proteins stored in the starchy endosperm, particularly the high-molecular-weight glutenin subunits (HMW-GS), which are important in determining gluten and dough elasticity. The quality of wheat cultivars depends on the number and composition of the HMW-GS present. We have introduced the HMW-GS 1Ax1 gene, known to be associated with good bread-making quality, into the Bob White cultivar of wheat (Triticum aestivum L.), in which it is not present in nature, by the biolistic bombardment of cultured immature embryos. Of the 21 independent transformed lines selected, 20 expressed the selectable bar gene, and nine the 1Ax1 gene. The amount of HMW-GS 1Ax1 protein produced in the different transgenic lines varied from 0.6% to 2.3% of the total protein, resulting in an increase of up to 71% in total HMW-GS proteins. The transgenic plants were normal, fertile, and showed Mendelian segregation of the transgenes. The accumulation of HMW-GS 1Ax1 was consistent and stable up to the R3 seed generation. These results demonstrate that it is possible to manipulate both the quantity and quality of HMW-GS, which influence the bread-making quality of wheat.

Biotechnology↗