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Biomedical subjects

V S Reddy

Publications and source records attributed to V S Reddy.

At least 19 recordsLinked to original sources
PubMed2003

High-frequency somatic embryo production and maturation into normal plants in cotton (Gossypium hirsutum) through metabolic stress.

A highly efficient somatic embryo production and maturation procedure has been developed to regenerate plantlets from cotton ( Gossypium hirsutum). This procedure involves the acceleration of differentiation through manipulations of nutrient and microenvironment conditions. Embryogenic calli, initiated from hypocotyls or cotyledonary leaf sections on MS medium containing 0.1 mg/l 2,4 dichlorophenoxyacetic acid, 0.5 mg/l kinetin, and 3% maltose produced globular-stage somatic embryos when transferred to hormone-free MS medium supplemented with high concentrations of nitrate. Subculture of globular embryos on hormone-free MS medium led to the development of torpedo- and cotyledonary-stage at a low frequency (two to four per plate) with the majority of embryos lacking further growth or entering into the dedifferentiation stage. Significant improvement in embryogenesis (two- to threefold) was achieved when calli were cultured on 1/5-strength MS medium irrespective of stress treatment. However, the frequency of globular embryos developing into normal plantlets improved considerably (20-24 per plate) when cultured on filter paper placed on MS medium. In this procedure, about 33% of globular embryos not only developed into the cotyledonary stage but rooted simultaneously, eliminating a separate rooting step. More than 70% of cotyledonary embryos developed into normal plantlets when cultured on full- strength MS medium containing 0.05 mg/l gibberellic acid.

2,4-Dichlorophenoxyacetic Acid↗
PubMed2003

Cerebral salt wasting syndrome in a patient with a pituitary adenoma.

Cerebral salt wasting syndrome (CSWS) is often an unrecognized cause of hyponatremia that occurs in the setting of intracranial lesions. It is important to differentiate CSWS from the syndrome of inappropriate ADH secretion, as this would alter the management of hyponatremia. We describe a case of CSWS that occurred in association with a non-functioning pituitary adenoma.

Adenoma↗
PubMed2001

Visualization of a water-selective pore by electron crystallography in vitreous ice.

The water-selective pathway through the aquaporin-1 membrane channel has been visualized by fitting an atomic model to a 3.7-A resolution three-dimensional density map. This map was determined by analyzing images and electron diffraction patterns of lipid-reconstituted two-dimensional crystals of aquaporin-1 preserved in vitrified buffer in the absence of any additive. The aqueous pathway is characterized by a size-selective pore that is approximately 4.0 +/- 0.5A in diameter, spans a length of approximately 18A, and bends by approximately 25 degrees as it traverses the bilayer. This narrow pore is connected by wide, funnel-shaped openings at the extracellular and cytoplasmic faces. The size-selective pore is outlined mostly by hydrophobic residues, resulting in a relatively inert pathway conducive to diffusion-limited water flow. The apex of the curved pore is close to the locations of the in-plane pseudo-2-fold symmetry axis that relates the N- and C-terminal halves and the conserved, functionally important N76 and N192 residues.

Amino Acid Sequence↗
PubMed2001

Modified Norwood operation for hypoplastic left heart syndrome.

BACKGROUND: We examined early results in infants with hypoplastic left heart syndrome undergoing the Norwood operation with perioperative use of inhaled nitric oxide and application of extracorporeal membrane oxygenation. METHODS: Medical records were reviewed retrospectively. RESULTS: Between April 1997 and March 2001, 50 infants underwent a modified Norwood operation for hypoplastic left heart syndrome. Mean age at operation was 7.5 +/- 5.7 days, and mean weight was 3.1 +/- 0.5 kg. Five infants had a delayed operation because of sepsis. The mean diameter of the ascending aorta by echocardiography was 3.6 +/- 1.8 mm. Ductal cannulation was used to establish cardiopulmonary bypass in all patients. Mean circulatory arrest time was 39.4 +/- 4.8 minutes. The size of the pulmonary-systemic shunt was 3.0 mm in 6 infants, 3.5 mm in 37, and 4.0 mm in 7. Infants with persistent hypoxia (partial pressure of oxygen < 30 mm Hg) received nitric oxide after they were weaned from cardiopulmonary bypass. Extracorporeal membrane oxygenation was initiated in 8 infants in the pediatric intensive care unit primarily for low cardiac output and in 8 in the operating room because of the inability to separate them from cardiopulmonary bypass. The 30-day mortality rate was 22% (11 of 50 patients), and the hospital mortality rate was 32% (16 of 50 patients). Mean follow-up was 17 months. Ten patients (20%) underwent stage-two repair, with one operative death. One survivor had a Fontan procedure, and 2 underwent heart transplantation, with one death. CONCLUSIONS: Early application of extracorporeal membrane oxygenation for hemodynamic instability and selective use of nitric oxide for persistent hypoxia in the immediate postoperative period may improve survival of patients with hypoplastic left heart syndrome. Renal failure requiring hemofiltration during extracorporeal membrane oxygenation (p < 0.05) and cardiopulmonary arrest in the pediatric intensive care unit (p < 0.05) were predictors of hospital mortality.

Administration, Inhalation↗
PubMed2001

Extracorporeal membrane oxygenation in children after repair of congenital cardiac lesions.

BACKGROUND: The purpose of this study was to review our experience in the early application of extracorporeal membrane oxygenation (ECMO) in patients requiring mechanical assistance after cardiac surgical procedures. METHODS: The hospital records of all children requiring ECMO after cardiac operation were retrospectively reviewed, and an analysis of variables affecting survival was performed. RESULTS: Fifty pediatric patients between May 1997 and October 2000 required ECMO for cardiopulmonary support after cardiac operation. Patients ranged in age from 1 day to 11 years (median age, 40 days). Forty-eight patients underwent repair of congenital cardiac lesions and 2 were included after receiving a heart transplant. Twenty-two children could not be weaned from cardiopulmonary bypass and were placed on ECMO in the operating room for circulatory support. Of the 28 children who required ECMO in the intensive care unit, 10 had ECMO instituted after cardiopulmonary arrest (mean cardiopulmonary resuscitation time 42 minutes; range, 5 to 110 minutes). In infants with single-ventricle physiology, survival to discharge was 61% (11 of 18 patients) as compared with 43% (14 of 32 patients) in those with biventricular physiology. Thirty of the 50 patients (60%) were successfully weaned from ECMO, of which 25 (83%) were discharged home. Overall survival to discharge in the entire cohort was 50%. Extracorporeal membrane oxygenation support greater than 72 hours was a grave prognostic indicator. Overall survival in this group was 36% (9 of 25 patients) compared with 56% (14 of 25 patients) in those with ECMO support less than 72 hours (p < 0.05). Univariate analysis revealed the presence of renal failure, extended periods of circulatory support, and a prolonged period of cardiopulmonary resuscitation as risk factors for mortality. The presence of shunt-dependent flow, operative procedure, and institution of ECMO in the intensive care unit did not alter survival. CONCLUSIONS: Extracorporeal membrane oxygenation provides effective support for postoperative cardiac and pulmonary failure refractory to medical management. Early institution of ECMO may decrease the incidence of cardiac arrest and end-organ damage, thus increasing survival in these critically ill patients.

Child↗
PubMed2001

Laparoscopic versus open splenectomy in the pediatric population: a contemporary single-center experience.

The purpose of this study was to compare a recent contemporaneous experience between laparoscopic (LS) and open (OS) splenectomy in children. All splenectomy cases between 1994 and 1999 at our institution were reviewed. The study included open and laparoscopic cases performed according to surgeon preference. Emergency splenectomies for trauma were excluded. The patient record was reviewed for the diagnosis, indications, postoperative length of stay, operative technique, postoperative complications, blood loss/blood transfusion, total amount of parenteral narcotics, and time to resumption of oral intake. Chi-square and t tests were used to compare measured differences for statistical significance. Between May 1994 and December 1999, 52 splenectomies were performed at Vanderbilt Children's Hospital. Of these, 45 were elective operations with 29 open and 16 laparoscopic procedures. During four OS and five LS operations a concomitant cholecystectomy was performed. The median patient age was 9.2 years (range 0.5 to 17.3). There was no statistical difference between the two groups in terms of age, weight, American Society of Anesthesiologists class, or estimated blood loss. There were no immediate postoperative complications in either group. There were no conversions from LS to OS. The mean duration of surgery was 264 minutes (LS) versus 169 minutes (OS) (P < 0.05). The average time to first oral intake was shorter in patients undergoing LS (1.1 vs 1.6 days, P < 0.05) and the mean postoperative length of stay was also shorter in the LS group (1.3 vs 3.1 days, P < 0.05). The use of postoperative intravenous narcotics (in morphine-equivalent doses) was significantly less in LS patients than in OS patients (7.5 mg or 0.15 mg/kg vs 46.9 mg or 1.5 mg/kg, P < 0.001), as was the need for PCA pump analgesia (90% in the OS group vs 25% in LS group, P < 0.01). Overall the average hospital charge (anesthesia fee, narcotics charge, and hospital room charge) was $5400 (range $4240-6250) in the OS group and $4950 (range $4450-6240) in the LS group (P < 0.05). Among the nine patients undergoing splenectomy with cholecystectomy, findings between the OS and LS groups were similar except for one late complication consisting of a diaphragmatic hernia in an LS patient. Both LS and OS with or without a concomitant procedure can be accomplished safely in children. LS appears to result in longer operative times but shorter lengths of stay, earlier first oral intake, and significantly fewer requirements for intravenous narcotics; all of these contribute to a reduction in hospital charges compared with the open operation.

Adolescent↗
PubMed2000

A calmodulin binding protein from Arabidopsis is induced by ethylene and contains a DNA-binding motif.

Calmodulin (CaM), a key calcium sensor in all eukaryotes, regulates diverse cellular processes by interacting with other proteins. To isolate CaM binding proteins involved in ethylene signal transduction, we screened an expression library prepared from ethylene-treated Arabidopsis seedlings with 35S-labeled CaM. A cDNA clone, EICBP (Ethylene-Induced CaM Binding Protein), encoding a protein that interacts with activated CaM was isolated in this screening. The CaM binding domain in EICBP was mapped to the C-terminus of the protein. These results indicate that calcium, through CaM, could regulate the activity of EICBP. The EICBP is expressed in different tissues and its expression in seedlings is induced by ethylene. The EICBP contains, in addition to a CaM binding domain, several features that are typical of transcription factors. These include a DNA-binding domain at the N terminus, an acidic region at the C terminus, and nuclear localization signals. In database searches a partial cDNA (CG-1) encoding a DNA-binding motif from parsley and an ethylene up-regulated partial cDNA from tomato (ER66) showed significant similarity to EICBP. In addition, five hypothetical proteins in the Arabidopsis genome also showed a very high sequence similarity with EICBP, indicating that there are several EICBP-related proteins in Arabidopsis. The structural features of EICBP are conserved in all EICBP-related proteins in Arabidopsis, suggesting that they may constitute a new family of DNA binding proteins and are likely to be involved in modulating gene expression in the presence of ethylene.

Amino Acid Motifs↗
PubMed2000

Crystal and solution structures of an HslUV protease-chaperone complex.

HslUV is a "prokaryotic proteasome" composed of the HslV protease and the HslU ATPase, a chaperone of the Clp/Hsp100 family. The 3.4 A crystal structure of an HslUV complex is presented here. Two hexameric ATP binding rings of HslU bind intimately to opposite sides of the HslV protease; the HslU "intermediate domains" extend outward from the complex. The solution structure of HslUV, derived from small angle X-ray scattering data under conditions where the complex is assembled and active, agrees with this crystallographic structure. When the complex forms, the carboxy-terminal helices of HslU distend and bind between subunits of HslV, and the apical helices of HslV shift substantially, transmitting a conformational change to the active site region of the protease.

ATP-Dependent Proteases↗
PubMed2000

A pollen-specific novel calmodulin-binding protein with tetratricopeptide repeats.

Calcium is essential for pollen germination and pollen tube growth. A large body of information has established a link between elevation of cytosolic Ca(2+) at the pollen tube tip and its growth. Since the action of Ca(2+) is primarily mediated by Ca(2+)-binding proteins such as calmodulin (CaM), identification of CaM-binding proteins in pollen should provide insights into the mechanisms by which Ca(2+) regulates pollen germination and tube growth. In this study, a CaM-binding protein from maize pollen (maize pollen calmodulin-binding protein, MPCBP) was isolated in a protein-protein interaction-based screening using (35)S-labeled CaM as a probe. MPCBP has a molecular mass of about 72 kDa and contains three tetratricopeptide repeats (TPR) suggesting that it is a member of the TPR family of proteins. MPCBP protein shares a high sequence identity with two hypothetical TPR-containing proteins from Arabidopsis. Using gel overlay assays and CaM-Sepharose binding, we show that the bacterially expressed MPCBP binds to bovine CaM and three CaM isoforms from Arabidopsis in a Ca(2+)-dependent manner. To map the CaM-binding domain several truncated versions of the MPCBP were expressed in bacteria and tested for their ability to bind CaM. Based on these studies, the CaM-binding domain was mapped to an 18-amino acid stretch between the first and second TPR regions. Gel and fluorescence shift assays performed with CaM and a CaM-binding synthetic peptide further confirmed MPCBP binding to CaM. Western, Northern, and reverse transcriptase-polymerase chain reaction analysis have shown that MPCBP expression is specific to pollen. MPCBP was detected in both soluble and microsomal proteins. Immunoblots showed the presence of MPCBP in mature and germinating pollen. Pollen-specific expression of MPCBP, its CaM-binding properties, and the presence of TPR motifs suggest a role for this protein in Ca(2+)-regulated events during pollen germination and growth.

Amino Acid Sequence↗
PubMed2000

Virus maturation targets the protein capsid to concerted disassembly and unfolding.

Many animal viruses undergo post-assembly proteolytic cleavage that is required for infectivity. The role of maturation cleavage on Flock House virus was evaluated by comparing wild type (wt) and cleavage-defective mutant (D75N) Flock House virus virus-like particles. A concerted dissociation and unfolding of the mature wt particle was observed under treatment by urea, whereas the cleavage-defective mutant dissociated to folded subunits as determined by steady-state and dynamic fluorescence spectroscopy, circular dichroism, and nuclear magnetic resonance. The folded D75N alpha subunit could reassemble into capsids, whereas the yield of reassembly from unfolded cleaved wt subunits was very low. Overall, our results demonstrate that the maturation/cleavage process targets the particle for an "off pathway" disassembly, because dissociation is coupled to unfolding. The increased motions in the cleaved capsid, revealed by fluorescence and NMR, and the concerted nature of dissociation/unfolding may be crucial to make the mature particle infectious.

Animals↗
PubMed2000

Embryology, anatomy, and surgical applications of the extrahepatic biliary system.

As technology has improved and the ability to apply this technology in the surgical arena has grown, surgeons have been able to perform more sophisticated operative procedures. Hepatobiliary surgeons are now able to use laparoscopy, immunosuppressive drugs, and technical advances in cryosurgery to accomplish magnificent results. The success and safety of laparoscopic cholecystectomy, orthotopic liver transplantation, and trisegmentectomy for hepatic tumors depend on a high regard for and an accurate knowledge of the anatomy and some of the common embryologic anomalies of the biliary tree. The blood supply, ductal variations, and gallbladder anatomy of this area are often the source of major challenge to unprepared and unaware surgeons. The authors have attempted to stimulate an interest in, a respect for, and perhaps some desire to learn more about the important and fascinating anatomy of this region.

Bile Duct Diseases↗
PubMed2000

The rice R gene family: two distinct subfamilies containing several miniature inverted-repeat transposable elements.

The R and B genes of maize regulate the anthocyanin biosynthetic pathway and constitute a small gene family whose evolution has been shaped by polyploidization and transposable element activity. To compare the evolution of regulatory genes in the distinct but related genomes of rice and maize, we previously isolated two R homologues from rice (Oryza sativa). The Ra1 gene on chromosome 4 can activate the anthocyanin pathway, whereas the Rb gene, of undetermined function, maps to chromosome 1. In this study, rice R genes have been further characterized. First, we found that an Rb cDNA can induce pigmentation in maize suspension cells. Second, another rice R homologue (Ra2) was identified that is more closely related to Ra1 than to Rb. Domesticated rice and its wild relatives harbor multiple Ra-like and Rb-like genes despite the fact that rice is a true diploid with the smallest genome of all the grass species analyzed to date. Finally, several miniature inverted-repeat transposable elements (MITEs) were found in R family members. Their possible role in hastening the divergence of R genes is discussed.

Amino Acid Sequence↗
PubMed2000

Cloning, expression, and sequence analysis of the gene encoding the alkali-stable, thermostable endoxylanase from alkalophilic, mesophilic Bacillus sp. Strain NG-27.

Alkalophilic Bacillus sp. strain NG-27 produces a 42-kDa endoxylanase active at 70 degrees C and at a pH of 8.4. The gene for this endoxylanase was cloned and sequenced. The gene contained one open reading frame of 1,215 bases. An active site characteristic of the family 10 beta-glycanases was recognized between amino acids 303 and 313, with the active glutamate at position 310. Though highly thermostable, the enzyme contains no cysteine residue.

Amino Acid Sequence↗
PubMed2000

Twenty-five-year surgical experience with pheochromocytoma in children.

Our objective was to analyze the presentation, diagnostic localization, operative management, histology, and long-term outcome of a single center's experience with pheochromocytomas in children. A chart review was done to identify all operatively managed pheochromocytomas in patients age 18 years or younger. Open and laparoscopic cases were included. We reviewed the presentation, diagnostic imaging, localization, operative management, pathology, and postoperative outcome of these patients. Clinic visits, contact with the tumor registry, and telephone interviews were used for follow-up. From 1973 through 1999, there were 11 children (four males and seven females) with 14 pheochromocytomas. Two (18.2%) patients had bilateral adrenal lesions and one patient had both adrenal and extra-adrenal tumors. Six (54.5%) patients had extra-adrenal lesions. The average age at operation was 14.7 years (range 9-18 years). Nine (82%) patients had significant hypertension at presentation. CT was used to localize the tumor in eight patients and urine catecholamine levels were used to confirm the diagnosis. Two of the cases were associated with inherited syndromes (multiple endocrine neoplasia 2A and von Hippel-Lindau). Ten patients underwent an open operation and one patient had a laparoscopic resection. The average patient follow-up was 9.2 years (range 9 months to 25 years). There were no operative complications and all patients were alive and well at the time of last follow-up. Three patients (27.2%) had tumors with microscopic malignant features. No tumors recurred or had evidence for metastatic spread. We conclude that peak incidence of pheochromocytomas in children is in early adolescence. Resection can be carried out safely with minimal morbidity and mortality. Current best management of this entity includes establishment of a biochemical diagnosis, adequate preoperative blockade, appropriate imaging, and an individualized operative approach based on tumor location and size.

Adolescent↗
PubMed1999

Longitudinal analysis of fibroblast growth factor expression after transplantation and association with severity of cardiac allograft vasculopathy.

BACKGROUND: Vascular smooth muscle cell growth factors are postulated to contribute to cardiac allograft vasculopathy (CAV). Few data quantitatively address the timing, location, or stimuli for growth factor expression and relationship to CAV. METHODS AND RESULTS: Acidic fibroblast growth factor (aFGF) mRNA expression was determined in serial endomyocardial biopsies during the first year after transplantation. Patients with high levels of aFGF mRNA and elevations after the early posttransplant period had significantly more severe CAV than patients with low aFGF and no late elevations. CONCLUSIONS: Parenchymal aFGF expression varies between patients and in the same patient over time and correlates with development of CAV.

Biopsy↗
PubMed1999

Interaction of a kinesin-like protein with calmodulin isoforms from Arabidopsis.

In Arabidopsis and other plants there are multiple calmodulin isoforms. However, the role of these isoforms in regulating the activity of target proteins is obscure. Here, we analyzed the interaction between a kinesin-like calmodulin-binding motor protein (Reddy, A. S. N., Safadi, F., Narasimhulu, S. B., Golovkin, M., and Hu, X. (1996) J. Biol. Chem. 271, 7052-7060) and three calmodulin isoforms (calmodulin-2, -4, and -6) from Arabidopsis using different approaches. Gel mobility and fluorescence shift assays revealed that the motor binds to all calmodulin isoforms in a calcium-dependent manner. Furthermore, all calmodulin isoforms were able to activate bovine calcium/calmodulin-dependent phosphodiesterase. However, the concentration of calmodulin-2 required for half-maximal activation of phosphodiesterase is 2- and 6-fold lower compared with calmodulin-4 and -6, respectively. The dissociation constants of the motor to calmodulin-2, -4, and -6 are 12.8, 27.0, and 27.8 nM, respectively, indicating that calmodulin-2 has 2-fold higher affinity for the motor than calmodulin-4 and -6. Similar results were obtained using another assay that involves the binding of (35)S-labeled calmodulin isoforms to the motor. The binding saturation curves of the motor with calmodulin isoforms have confirmed that calmodulin-2 has 2-fold higher affinity to the motor. However, the affinity of calmodulin-4 and -6 isoforms for the motor was about the same. Based on these studies, we conclude that all calmodulin isoforms bind to the motor protein but with different affinities.

3',5'-Cyclic-AMP Phosphodiesterases↗