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Biomedical subjects

R Chaturvedi

Publications and source records attributed to R Chaturvedi.

At least 19 recordsLinked to original sources
PubMed2004

In vitro morphogenesis in zygotic embryo cultures of neem (Azadirachta indica A. Juss.).

Immature zygotic embryo cultures of neem yielded highly regenerative cultures, with the response varying with the embryo stage at culture. Early dicotyledonous stage embryos were the most responsive followed by torpedo stage embryos. The embryo cultures differentiated three types of regenerants: somatic embryos (SEs), shoot buds and neomorphs. SEs exhibited morphological abnormalities such as pluricotyledony, fusion of cotyledons and absence of cotyledons. Although these SEs showed secondary embryogenesis, the occurrence of normal dicotyledonous embryos was extremely rare. On MS basal medium 3% of SEs developed a long tap root but a plumular shoot did not appear. However, it was possible to regenerate plantlets from immature zygotic embryo cultures of neem via neomorph formation and adventitious shoot bud formation. The transplantation survival of these plants was more than 80%.

Azadirachta↗
PubMed2004

CompuCell, a multi-model framework for simulation of morphogenesis.

MOTIVATION: CompuCell is a multi-model software framework for simulation of the development of multicellular organisms known as morphogenesis. It models the interaction of the gene regulatory network with generic cellular mechanisms, such as cell adhesion, division, haptotaxis and chemotaxis. A combination of a state automaton with stochastic local rules and a set of differential equations, including subcellular ordinary differential equations and extracellular reaction-diffusion partial differential equations, model gene regulation. This automaton in turn controls the differentiation of the cells, and cell-cell and cell-extracellular matrix interactions that give rise to cell rearrangements and pattern formation, e.g. mesenchymal condensation. The cellular Potts model, a stochastic model that accurately reproduces cell movement and rearrangement, models cell dynamics. All these models couple in a controllable way, resulting in a powerful and flexible computational environment for morphogenesis, which allows for simultaneous incorporation of growth and spatial patterning. RESULTS: We use CompuCell to simulate the formation of the skeletal architecture in the avian limb bud. AVAILABILITY: Binaries and source code for Microsoft Windows, Linux and Solaris are available for download from http://sourceforge.net/projects/compucell/

Animals↗
PubMed2002

Production of haploids of neem (Azadirachta indica A. Juss.) by anther culture.

Androgenic haploids of the neem tree (Azadirachta indica A. Juss.) were produced by anther culture at the early- to late-uninucleate stage of pollen. Haploid formation occurred via callusing. The best medium for inducing callusing in the anther cultures was Murashige and Skoog's basal medium (MS) (9% sucrose) supplemented with 1 microM 2,4-D, 1 microM NAA and 5 microM BAP, while anther callus multiplied best on MS medium supplemented with 1 microM 2,4-D and 10 microM Kn. These calli differentiated shoots when transferred to a medium containing BAP; 5 microM BAP was optimum for young calli (75% cultures differentiated shoots), but older calli showed the best regeneration with 7.5 microM BAP. Shoots elongated at a lower concentration of BAP-0.5 microM. These shoots were multiplied by forced axillary branching and rooted in vitro. The plants were subsequently established in soil. Of the plants that regenerated from anther callus 60% were haploid, 20% were diploid and 20% were aneuploid.

2,4-Dichlorophenoxyacetic Acid↗
PubMed2001

Estrogen receptors in rat bone: their interaction with estrogen receptor modulators.

Estrogen receptors (ER) were studied in rat bone cytosol using immunoprecipitation, and Western blot technique. Ligand specificity of bone ER was studied using various known modulators of ER. Competitive experiments were performed under exchange conditions in bone tissue obtained from one day old rats. ER alpha and beta subtypes were identified using immunoblotting experiments compared with that of ovarian and uterine tissues. In competitive binding assay, maximum inhibition in specific 3H-E2 binding was shown by E2 followed by tamoxifen and diethylstilbestrol. 7-Hydroxycentchroman and 85/287 also inhibited specific 3H-E2 binding but were less potent as compared to tamoxifen and diethylstilbestrol. However, 85/287 was less effective (81%) as compared to 7-hydroxycentchroman. Polyacrylamide gel electrophoresis of cytosol and Western blot analysis revealed the presence of 55 kD and 66 kD ER immunoreactive bands corresponding to alpha and beta subtypes, respectively, in bone as well as in uterus. Interestingly, the concentration of 55 kD ER was 3-fold higher than that of 66 kD ER. Ovarian cytosol revealed the presence of a 55 kD band only in Western blot analysis. These studies suggest the action of estrogens/ER modulators on osteoblasts which contain a limited number of classical alpha as well as beta sub types of ER that are known to be structurally different in their hormone-binding domains.

Animals↗
PubMed2000

The delta-endotoxin proteins accumulate in Escherichia coli as a protein-DNA complex that can be dissociated by hydrophobic interaction chromatography.

The insecticidal protein CryIAc accumulated to form inclusion bodies in Escherichia coli upon overexpression of the cloned gene. The solubilized inclusion bodies contained the delta-endotoxin in association with DNA fragments of about 25 kb. The protein-DNA complex could be dissociated and the delta-endotoxin purified by hydrophobic interaction chromatography on phenyl-Sepharose. The DNA was washed out in the high-salt buffer while the delta-endotoxin was bound to the matrix and was eluted at 4 degrees C by a stepwise decreasing potassium chloride gradient. The DNA-protein complex also contained plasmids harbored by the host strain. The plasmid DNA associated with the complex became competent to transform E. coli only after it was dissociated from the delta-endotoxin. The hydrophobic interaction chromatography provides an efficient method for the purification of DNA-free activated toxin.

Bacillus thuringiensis↗
PubMed2000

Degradation and de novo synthesis of D1 protein and psbA transcript levels in Chlamydomonas reinhardtii during UV-B inactivation of photosynthesis and its reactivation.

UV-B induces intensity and time dependent inhibition of photosynthetic O2 evolution and PS II electron transport activity in Chlamydomonas reinhardtii. The D1 and D2 proteins of chloroplast membranes are rapidly and specifically degraded in the course of irradiation of cells to UV-B. Continuous synthesis of the two proteins was essential for the repair of damaged PS II as chloramphenicol accelerated UV-B inactivation of photosynthesis and prevented photoreactivation. Northern analysis revealed that UV-B also affected the expression of psbA gene coding for the D1 protein. Cells showing 72% inhibition of PS II activity, revealed a modest net loss of 25% in the level of D1 protein. This shows that synthesis of D1 protein is not the only component involved in the recovery process. Our results indicate that besides affecting the synthesis of the D1 protein UV-B may impair certain post-translational events, which in turn may limit the repair of damaged PS II.

Animals↗
PubMed2000

Effect of light intensity on in vitro multiple shoot induction and regeneration of cotton (Gossypium hirsutum L. cv Khandawa-2).

Cotyledonary nodes taken alongwith shoot apex from seedlings of cotton (G. hirsutum) proliferated into shoots on nutrient agar medium supplemented with cytokinins. In the presence of optimal plant growth regulators, low light intensity enhanced the number of shoots initiated per explant in cotton. An average of 33.5 +/- 2.9 shoots were obtained from a single explant cultured for 8 weeks which is about four fold higher than the values reported in earlier protocols. The isolated shoots were rooted on nutrient agar medium supplemented with alpha-naphthalene acetic acid and transferred to soil after acclimatization. Regenerated plants were morphologically identical to the seed-germinated plants and were fertile.

Culture Media↗
PubMed2000

Cranial irradiation--an unusual cause for diabetes insipidus.

Central diabetes insipidus frequently occurs due to tumours in the region of pituitary or hypothalamus or following surgical trauma to these regions. Rarely it has been reported following cranial irradiation. We report the case of a middle aged woman who underwent surgical removal of a frontal capillary hemangioblastoma and received cranial irradiation. She presented ten months later with features of diabetes insipidus which was confirmed to be of central origin. She responded well to desmopressin nasal spray. Radiation induced damage to the hypothalmo-pituitary axis presents usually with anterior pituitary hormone deficiencies, most commonly that of growth hormone. Presentation as central diabetes insipidus is very uncommon.

Cerebellar Neoplasms↗
PubMed1999

Antioxidant protection against iron toxicity: plasma changes during cardiopulmonary bypass in neonates, infants, and children.

Cardiopulmonary bypass surgery is associated with the release of low molecular mass iron, which increases the saturation of plasma transferrin to over 50% in all adult patients treated. In a significant minority, however plasma transferrin becomes 100% iron saturated and non-transferrin bound iron can be detected in the plasma. An iron-saturated transferrin is also a common physiological finding in normal term and pre-term infants at a time when their plasma antioxidants, which protect against iron toxicity and radical scavenging, are profoundly different from those seen in adults. This study was conducted to assess the extent to which antioxidants, which protect against iron toxicity, are altered in neonates, infants, and children undergoing cardiopulmonary bypass surgery.

Antioxidants↗
PubMed1999

Urgent homograft aortic root replacement for aortic root abscess in infants and children.

OBJECTIVE: To assess the results of early homograft aortic root replacement in infants and children with an aortic root abscess. DESIGN: Descriptive study of all patients with an aortic root abscess during 1987-97, identified by retrospective review of the echocardiographic and surgical registries. SETTING: A tertiary referral centre. PATIENTS: Five patients (age 0.6 to 13 years; two female) were identified with an aortic root abscess. Four had no known pre-existing congenital heart abnormality. Three had a misleading presentation and were referred to our hospital with non-cardiac diagnoses (fulminant hepatic failure; adult respiratory distress syndrome; cerebrovascular accident). The other two presented with septicaemia and a murmur, respectively. Blood cultures identified Staphylococcus aureus (n = 3) and Streptococcus pneumoniae (n = 2). Aortic root abscess was diagnosed by transthoracic echocardiography. INTERVENTIONS: Homograft aortic root replacement with coronary reimplantation was performed urgently (median one day after diagnosis). RESULTS: Four patients survived. The youngest died following multiorgan failure, multiple aortic fistulae, three valve involvement, and extensive tissue destruction preventing mitral valve replacement (S pneumoniae). Two of the four survivors have required further surgery: mitral valve replacement (0.3 years later), and pulmonary autograft replacement of the homograft (8.3 years later). All survivors remain in sinus rhythm and New York Heart Association functional class I. CONCLUSIONS: Infective endocarditis should be considered in any child with severe septicaemia or embolic phenomena. Echocardiographic diagnosis of an aortic root abscess indicates uncontrolled infection and impending haemodynamic collapse. Homograft aortic root replacement can be performed successfully in critically ill children with active infection.

Abscess↗
PubMed1998

Impact of a Simple Inexpensive Quality Assurance Effort on Physician's Choice of Thrombolytic Agents and Door-to-Needle Time: Implication for Costs of Management.

The objective of this study were to assess the impact of a quality assurance effort on the door-to-needle time and the choice of thrombolytic agent for the management of acute myocardial infarction in the emergency department. The study design involved a prospective collection of data on a series of consecutive patients who received a thrombolytic agent for a presumed acute myocardial infarction. The study was carried out in the emergency department of a major university urban tertiary care center. A total of 349 patients were studied from September 1989 to March 1994. The quality assurance program began in 1989 and included chart review of all patients receiving thrombolytic therapy, with special attention to all patients with door-to-needle times >60 minutes to identify causes for delay. Feedback was directed to pharmacy, nursing, and physician staff. Biannual reports were distributed throughout the hospital and the emergency department. Nursing-specific feedback led to the development of protocols for all aspects of the delivery of thrombolytic agents. The choice of thrombolytic agent was not dictated by the protocol, but the physician staff was continuously updated on the results of the latest clinical trials comparing one thrombolytic agent with another. The mean age was 58 years for men and 67 years for women in this cohort consisting of 78% men and 22% women. Thirty-seven percent of the myocardial infarctions were in an anterior location and 56% were in an inferior location. The median duration of chest pain before presentation to the emergency department was 120 minutes. Hospital mortality was 3%. Median door-to-needle time fell from 46 (1989-1991) to 36 (1992-1994) minutes, P& < 0.01. The percentage of patients with a door-to-needle time >60 minutes decreased from 35% (1989-1991) to 16% (1992-1994) minutes, P < 0.0001. Corresponding with the ISIS-3 report, there was a significant increase in the proportion of patients receiving streptokinase over the first 3 years of the study (P < 0.0001), which changed to a trend toward increased utilization of tissue plasminogen activator with the GUSTO report in the final 6 months of the study. In conclusion, a quality assurance program led to a significant reduction in the door-to-needle time, and recent megatrials were found to influence the choice of thrombolytic agent used.

Journal Article↗
PubMed1998

Purification of alpha feto protein from human cord blood.

Alpha Fetoprotein (AFP) is a major serum protein in the developing fetus and is of clinical significance as it is an oncofetal protein being synthesized by fetal organs and malignant tumors. AFP is here used as a diagnostic marker for hepatic carcinomas. In view of structural homology and similarities in physico-chemical properties with serum albumin, the separation and purification of AFP has always been a problem. Immunologically active AFP has been purified from human cord plasma using pseudoaffinity chromatography based on Cibacron blue substituted Sephadex G-100. AFP was quantified using rocket immunoelectrophoresis and double sandwich ELISA. Polyclonal antibodies were raised against purified AFP in mice. The purified antibodies were conjugated with peroxidase for use in double antibody sandwich ELISA. Purification of AFP from human cord plasma by an improved method with 55% recovery is reported.

Animals↗
PubMed1997

Resting right ventricular function in patients with coronary artery disease: pressure volume analysis using conductance catheters.

Right ventricular pressure volume cycles from patients with coronary artery disease were created in order to assess their characteristics and the effects of peak ventricular pressure and right and left artery coronary disease. Thirty-three patients undergoing diagnostic catheterisation for ischaemic heart disease underwent right ventricular catheterisation with a micromanometer and a conductance catheter. Simultaneous pressure and volume signals were recorded and analysed as functions of time, and of each other, forming pressure volume cycles. A total of 19/33 (58%) patients had an abnormal pressure volume loop with a clear end systolic shoulder, and an isovolumic relaxation phase. The mean peak ventricular pressure for all patients was raised (35.2 S.D. 11.8 mmHg), but there was no correlation between indices of shape and peak systolic pressure. Values of dP/dtmax were also raised, but there was no significant difference in this or any other index between patients with left or right coronary artery disease. Thus, in patients with coronary artery disease, the right ventricular pressure volume loop is frequently abnormal in a pattern that is recognised as a feature of an increased ventricular afterload.

Angina Pectoris↗
PubMed1997

Clinical application of the conductance catheter technique in the adult human right ventricle.

This study examines the use of conductance catheters to assess human right ventricular volume. Ten patients undergoing diagnostic cardiac catheterisation underwent right heart catheterisation with a conductance catheter and micromanometer, and a thermodilution catheter before and after fluid loading. Parallel wall conductance (Vc), and the multiplication factor relating conductance and thermodilution derived stroke volumes (å) were derived at each steady state. Pressure-volume cycles were analyzed at steady state and during fluid loading. Fluid loading resulted in a significant increase in cardiac output, and change in maximum and minimum cycle volume. There was no significant change in å (mean 0.40 S.D. 0.20) or Vc (mean 126.4 S.D. 59.6 ml) at higher cardiac outputs or ventricular volumes. Right ventricular pressure-volume cycles were formed demonstrating characteristic lack of clear isovolumic contraction and relaxation phases, and low cycle efficiencies (mean 0.62 S.D. 0.16). Serial cycles recorded during volume loading defined an end systolic pressure-volume relation more reliably than a stroke work end diastolic volume relation. Thus, a conductance derived volume signal can be obtained in the human right ventricle which can be interpreted as a continuous and instantaneous index of right ventricular volume, allowing the construction of real time pressure-volume cycles.

Adult↗