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V S Reddy

Publications and source records attributed to V S Reddy.

At least 37 records · Page 2Linked to original sources
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↗
PubMed1999

Granulocyte colony-stimulating factor-mobilized allogeneic stem cell transplantation maintains graft-versus-leukemia effects through a perforin-dependent pathway while preventing graft-versus-host disease.

Minimization of graft-versus-host disease (GVHD) with preservation of the graft-versus-leukemia (GVL) effect is a crucial step to improve the overall survival of allogeneic bone marrow transplantation (BMT) for patients with hematological malignancies. We and other investigators have shown that granulocyte colony-stimulating factor (G-CSF)-mobilized allogeneic peripheral stem cell transplantation (PBSCT) reduces the severity of acute GVHD in murine models. In this study, we investigated whether G-CSF-mobilized PBSC maintain their GVL effect in a murine allogeneic transplant model (B6 --> B6D2F1). B6 mice (H-2(b)) were injected subcutaneously with human G-CSF (100 micrograms/kg/d) for 6 days and their splenocytes were harvested on day 7 as a source of PBSC. G-CSF mobilization dramatically improved transplant survival compared with nonmobilized controls (95% v 0%, P <.001). Systemic levels of lipopolysaccharide and tumor necrosis factor-alpha were markedly reduced in recipients of allogeneic G-CSF-mobilized donors, but cytolytic T lymphocyte (CTL) activity against host tumor target cells p815 was retained in those recipients. When leukemia was induced in recipients by coinjection of p815 tumor cells (H-2(d)) at the time of transplantation, all surviving recipients of G-CSF-mobilized B6 donors were leukemia-free at day 70 after transplant, whereas all mice who received T-cell-depleted (TCD) splenocytes from G-CSF-mobilized B6 donors died of leukemia. When splenocytes from G-CSF-mobilized perforin-deficient (pfp-/-) mice were used for transplantation, 90% of recipients died of leukemia, demonstrating that perforin is a crucial pathway mediating GVL effects after G-CSF-mobilized PBSCT. These data illustrate that G-CSF-mobilized allogeneic PBSCT separate GVL from GVHD by preserving perforin-dependent donor CTL activity while reducing systemic inflammation.

Animals↗
PubMed1999

Molecular characterization of a plant mitochondrial chaperone GrpE.

Escherichia coli DnaK (Hsp70) cooperates with DnaJ and GrpE in its essential role as a molecular chaperone. Function of mitochondrial Hsp70 (mHsp70) in protein folding and organellar import in eukaryotes is critically dependent on GrpE. We cloned two genes from tobacco (Nicotiana tabacum) BY2 cells based on peptide sequences from a purified protein. The predicted amino acid sequences of both clones resembled that of GrpE from E. coli and its homologues from eukaryotes, and a cDNA clone from Arabidopsis thaliana. One gene (Type 1) encoded a deduced protein that was identical to the purified protein while the other (Type 2) encoded a deduced protein that has 80% sequence identity to Type 1. Both tobacco and Arabidopsis thaliana GrpE homologues bound to DnaK and ATP inhibited this binding. The tobacco GrpE homologue contained a typical N-terminal mitochondrial target presequence of 64 residues and the presequence directed the green fluorescent protein to tobacco mitochondria. The tobacco GrpE homologue also associated with mHsp70 when reintroduced into BY2 protoplasts, and this association was disrupted by ATP. A three-dimensional structure for the tobacco GrpE homologue was modeled based on the X-ray structure of E. coli GrpE complexed with DnaK. The modeled structure has the same overall structure as E. coli GrpE. We propose that the tobacco GrpE homologue interacts with mHsp70 in a manner analogous to E. coli GrpE with DnaK and designate it as tobacco mitochondrial GrpE (NtmGrpE).

Amino Acid Sequence↗
PubMed1999

Glyoxalase I from Brassica juncea: molecular cloning, regulation and its over-expression confer tolerance in transgenic tobacco under stress.

Despite its ubiquitous presence, the role of glyoxalase I has not been well investigated in plants. In order to find out its physiological functions, we have cloned and characterized a cDNA from Brassica juncea encoding glyoxalase I (Gly I) and made transgenic tobacco plants harbouring Gly I in both sense and antisense orientation. The transgenic nature of the plants was confirmed by Southern blotting, and the estimated number of genes inserted ranged from one to six. The transcript and protein levels of glyoxalase I were also monitored in transgenic plants. The expression of glyoxalase I in B. juncea was upregulated in response to salt, water and heavy metal stresses. In response to a high concentration of salt, the transcript level averaged threefold higher in 72 h, and an increase in the protein was also seen by immunoblotting. The transgenic plants over-expressing glyoxalase I showed significant tolerance to methylglyoxal and high salt, as tested in detached leaf disc senescence assay. A comparison of plants expressing high and low levels of glyoxalase I showed that the tolerance to different salt concentrations was correlated with the degree of glyoxalase I expression. Our results suggest an important role of glyoxalase I in conferring tolerance to plants under stress conditions.

Adaptation, Physiological↗
PubMed1998

Imaging RNA and dynamic protein segments with low-resolution virus crystallography: experimental design, data processing and implications of electron density maps.

Single crystal diffraction data were collected from virus crystals in the resolution range of 270 to 14 A using a synchrotron X-ray source and a small-angle scattering instrument adapted for single crystal measurements. Reflections were measured from single crystals of the capsid of the double-stranded DNA bacteriophage HK97 and synthetic Flock House virus-like particles (sFHV). The quality of the low-resolution measurements was confirmed by excellent scaling statistics for both data sets. The sFHV amplitudes between 270 and 90 A resolution were closely similar to independently measured solution scattering data, and to data calculated from the Fourier transform of a uniform density sphere of 315 A diameter. A rotation function computed with the sFHV data between 70 and 20 A resolution was readily interpretable. A uniform density sphere model was used to compute phases for measured amplitudes between 270 and 68 A resolution. The calculated phases were refined and extended to 14 A resolution with real space averaging employing an external mask shape defined by the high-resolution structure. The resulting electron density map displayed regions interpretable as loosely ordered RNA that connected ordered RNA segments seen in a published 3.0 A resolution map. The published high-resolution electron density map lacked data inside 15 A resolution and the interior of the particle in that map appeared hollow. Difference electron density maps corresponding to bulk RNA were computed by subtracting the contribution of the protein shell, based on the available high-resolution atomic model, from either the cryo-electron microscopy density or the low-resolution X-ray density. Features of the RNA were closely similar in the cryo-electron microscopy and X-ray maps, demonstrating the consistency of the two imaging methods. Electron density maps computed at 14 and 6 A resolution with the X-ray amplitudes showed that RNA contributed little to the scattering beyond 14 A resolution.

Bacteriophages↗
PubMed1998

The futility of chest roentgenograms following routine central venous line changes.

OBJECTIVE: To demonstrate chest roentgenograms after central venous line changes over a guidewire delay the use of the central lines and increases charges with no change of morbidity or the rate of complication. METHODS: Retrospective study using the Surgical Intensive Care database followed by a nonrandomized, prospective study of central venous line changes. The total time from the catheter change until chest radiograph confirmation and an analysis of charges was done. RESULTS: The retrospective study of 1,201 central line changes demonstrated no pneumothorax and two central lines malpositioned. The prospective study of 100 patients demonstrated no pneumothorax and one catheter malpositioned. The average time from completion of the central line change until the radiographic confirmation was 60.2 minutes. The charge for the chest x-ray film was $156. CONCLUSIONS: The combined studies composed of 1,301 patients demonstrated no pneumothorax and three malpositioned catheters. This study demonstrates that radiographic confirmation of central venous line placement after routine line change is of no benefit as the malpositioned catheters caused no morbidity, produces significant delays and increases medical charges to the patient. Extrapolation predicts an annual reduction of $46,800 in the Vanderbilt Surgical Intensive Care Unit.

Catheterization, Central Venous↗
PubMed1998

Energetics of quasiequivalence: computational analysis of protein-protein interactions in icosahedral viruses.

Quaternary structure polymorphism found in quasiequivalent virus capsids provides a static framework for studying the dynamics of protein interactions. The same protein subunits are found in different structural environments within these particles, and in some cases, the molecular switching required for the polymorphic quaternary interactions is obvious from high-resolution crystallographic studies. Employing atomic resolution structures, molecular mechanics, and continuum electrostatic methods, we have computed association energies for unique subunit interfaces of three icosahedral viruses, black beetle virus, southern bean virus, and human rhinovirus 14. To quantify the chemical determinants of quasiequivalence, the energetic contributions of individual residues forming quasiequivalent interfaces were calculated and compared. The potential significance of the differences in stabilities at quasiequivalent interfaces was then explored with the combinatorial assembly approach. The analysis shows that the unique association energies computed for each virus serve as a sensitive basis set that may determine distinct intermediates and pathways of virus capsid assembly. The pathways for the quasiequivalent viruses displayed isoenergetic oligomers at specific points, suggesting that these may determine the quaternary structure polymorphism required for the assembly of a quasiequivalent particle.

Animals↗
PubMed1998

Clinical characteristics, seizure spread patterns and prognosis of seizures associated with a single small cerebral calcific CT lesion.

Clinical characteristics of 97 patients with epilepsy associated with a small single cerebral calcific CT lesion (SSCCCTL), measuring 20 mm or less were analysed. The mean age was 20 years and 60% were in the first and second decades. Eighteen (18.5%) patients had a previous history of unprovoked seizures, with complex partial seizures (61%) being the most common type. Seizures could be localized to a single ILAE site in 73% of patients. None had neurological deficit and electroencephalograph abnormalities were noted in 29% of patients. Fifty-one (53%) patients had breakthrough seizures and were more common with frontal location. By 7 years 71.5% (95% confidence intervals (CI) 53.7-85.4) of patients achieved 3-year remission and 66% (CI 32.4-88.2) had achieved 5-year remission. The clinical pattern of the seizures was clearly distinctive to allow it to be localized to the location of the lesion on computerized tomography (CT) scan in 25 (26%) patients and in another 31 (31%) patients nearer to the anatomical site of the lesion on the CT scan. There was discordance between clinical localization and CT location of the lesion in 15 patients. Nine of the 10 patients with occipital or parieto-occipital location had focal tonic-clonic seizures with secondary generalization. Both patients with temporal location had motor seizures. The relevance of these findings to the seizure propagation was discussed.

Adolescent↗
PubMed1997

The structure of alfalfa mosaic virus capsid protein assembled as a T=1 icosahedral particle at 4.0-A resolution.

K. Fukuyama, S. S. Abdel-Meguid, J. E. Johnson, and M. G. Rossmann (J. Mol. Biol. 167:873-984, 1983) reported the structure of alfalfa mosaic virus assembled from the capsid protein as a T=1 icosahedral empty particle at 4.5-A resolution. The information contained in the structure included the particle size, protein shell thickness, presence of wide holes at the icosahedral fivefold axes, and a proposal that the capsid protein adopts a beta-barrel structure. In the present work, the X-ray diffraction data of Fukuyama et al. as well as the data subsequently collected by I. Fita, Y. Hata, and M. G. Rossmann (unpublished) were reprocessed to 4.0-A resolution, and the structure was solved by molecular replacement. The current structure allowed the tracing of the polypeptide chain of the capsid protein confirming the beta-sandwich fold and provides information on intersubunit interactions in the particle. However, it was not possible to definitively assign the amino acid sequence to the side chain density at 4-A resolution. The particle structure was also determined by cryoelectron microscopy and image reconstruction methods and found to be in excellent agreement with the X-ray model.

Alfalfa mosaic virus↗
PubMed1996

In vitro and in vivo characterization of a 99mTc complex with tris(hydroxymethyl)phosphine (THP).

The water-soluble, monophosphine ligand tris(hydroxymethyl)phosphine (THMP) was complexed with 99mTc. The 99mTc-THMP was formed in high radiochemical purity by simply mixing 99mTcO4- with THMP over a wide pH range. In vitro and in vivo studies indicated the complex to be highly stable under the respective conditions. HPLC analysis indicated a singular species with a retention time identical to the known [ReO2(THMP)4]1 complex. Results show that the hydroxymethylphosphine functionality is attractive for use in designing new 99mTc radiopharmaceuticals.

Animals↗
PubMed1994

Capsid assembly in a family of animal viruses primes an autoproteolytic maturation that depends on a single aspartic acid residue.

Maturation of noninfectious nodavirus provirions occurs by autoproteolytic cleavage of most of the 180 copies of the alpha-protein that make up the icosahedral capsid. This maturation, which is much slower than viral assembly, produces an infectious particle that is more stable than the provirion and makes viral uncoating thermodynamically distinct from assembly, allowing assembly and (a time-delayed) uncoating to occur under similar conditions. The results of structural, computational, and molecular genetic studies suggest that maturation depends both on intrasubunit strain, produced during assembly, and on a critical aspartic acid residue. This residue lies in a hydrophobic pocket that is stabilized by intersubunit contacts. It is close to the scissile bond and exhibits an environmentally elevated pKa. The apparent involvement of a single acidic residue in the hydrolytic cleavage of a peptide bond contrasts with the involvement of 2 such residues in acid proteases.

Aspartic Acid↗
PubMed1994

Functional implications of quasi-equivalence in a T = 3 icosahedral animal virus established by cryo-electron microscopy and X-ray crystallography.

BACKGROUND: Studies of simple RNA animal viruses show that cell attachment, particle destabilization and cell entry are complex processes requiring a level of capsid sophistication that is difficult to achieve with a shell containing only a single gene product. Nodaviruses [such as Flock House virus (FHV)] are an exception. We have previously determined the structure of FHV at 3 A resolution, and now combine this information with data from cryo-electron microscopy in an attempt to clarify the process by which nodaviruses infect animal cells. RESULTS: A difference map was computed in which electron density at 22 A resolution, derived from the 3.0 A resolution X-ray model of the FHV capsid protein, was subtracted from the electron density derived from the cryo-electron microscopy reconstruction of FHV at 22 A resolution. Comparisons of this density with the X-ray model showed that quasi-equivalent regions of identical polypeptide sequences have markedly different interactions with the bulk RNA density. Previously reported biphasic kinetics of particle maturation and the requirement of subunit cleavage for particle infectivity are consistent with these results. CONCLUSIONS: On the basis of this study we propose a model for nodavirus infection that is conceptually similar to that proposed for poliovirus but differs from it in detail. The constraints of a single protein type in the capsid lead to a noteworthy use of quasi-symmetry not only to control the binding of a 'pocket factor' but also to modulate maturation cleavage and to release a pentameric helical bundle (with genomic RNA attached) that may further interact with the cell membrane.

Capsid↗
PubMed1994

The refined three-dimensional structure of an insect virus at 2.8 A resolution.

The structure of the black beetle nodavirus has been refined at 2.8 A resolution by alternate use of restrained least-squares atomic coordinate refinement and phase refinement by real space averaging with the 5-fold non-crystallographic symmetry in the crystal. The coordinates were also refined by simulated annealing. The final R-factor for all data with I/sigma(I) > 4 was 22.1%. A total of 7692 atoms were refined in one icosahedral asymmetric unit which included 273 oxygen atoms of ordered water molecules. Three identical gene products of 407 amino acids form one icosahedral asymmetric unit. Each is located in a structurally unique position, identified as A, B or C, consistent with a T = 3 quasi equivalent lattice. Icosahedral pentamers are formed by A subunits while B and C subunits alternate about icosahedral 3-fold axes to form quasi hexamers. Five calcium ions are located within the icosahedral asymmetric unit and stabilize the quasi 3-fold related intersubunit contacts between A, B and C. The final model consists of coordinates for residues 56 to 379 of all three subunits and residues 20 to 31 from the C subunit only. Atom positions for the sugar-phosphate backbone were modeled for ten nucleotides close to the icosahedral 2-fold axes. Symmetry equivalent polyribonucleotides form a helical duplex at each icosahedral 2-fold axis. The three subunits display an eight-stranded beta-barrel fold, very similar to the subunit structures observed in most other icosahedral RNA viruses analyzed. Quasi equivalence is regulated by the ordered RNA and residues 20 to 31 in the C subunit to form a "flat inter subunit contact" at icosahedral 2-fold joints. The RNA and polypeptide are disordered at the quasi 2-fold joints and this results in a "bent inter subunit contact". Although similar quaternary structures were seen in T = 3 plant viruses studied, RNA did not play a role as a molecular switch in those structures. The autocatalytic, post assembly, cleavage of the initial gene product at residue Asn363/Ala364 to form a stable and infectious particle is probably the result of an acid catalyzed main-chain hydrolysis in which Asp75 is the proton donor. The reaction is initiated by assembly which places Asp75 in a hydrophobic environment created by quaternary interactions which raises its pK to 5.6. The region in which the reaction occurs is formed by an internal helical bundle that has not been seen in other virus structures.

Amino Acid Sequence↗