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S Veeraraghavan

Publications and source records attributed to S Veeraraghavan.

At least 19 recordsLinked to original sources
PubMed2001

Ace gene I/D polymorphism and sarcoidosis pulmonary disease severity.

Previous studies of the insertion/deletion (I/D) polymorphism of the angiotensin-converting enzyme (ACE) gene in sarcoidosis have revealed both ethnic heterogeneity of I/D frequencies and controversy surrounding the association between the polymorphism and severity of disease. The objective of this study was, therefore, to clarify the role of the ACE I/D polymorphism in (1) disease susceptibility, (2) pulmonary disease severity (with particular reference to pulmonary fibrosis), and (3) pulmonary disease progression, in two distinct European sarcoidosis populations. Standard chest radiographic staging was performed on 118 UK and 56 Czech white patients with sarcoidosis at 2 yr from presentation. Pulmonary function data were analyzed, and patients were then categorized according to disease severity. A PCR-SSP assay was used to determine the ACE I/D genotype of each patient studied. The I/D allele frequencies from these patients were compared with frequencies from ethnically matched UK (n = 386) and Czech (n = 179) control subjects using a chi-square contingency table. No significant differences were seen in the distribution of the ACE I/D genotypes, allele frequencies or phenotype frequencies. Furthermore, no association was found between the ACE I/D polymorphism and pulmonary disease severity, fibrosis, and progression. We conclude that the ACE I/D polymorphism has no role in sarcoidosis susceptibility in European whites and that it is not a regulatory variant in this disease.

Adult↗
PubMed2000

Integrin alpha(3)-subunit expression modulates alveolar epithelial cell monolayer formation.

We investigated expression of the alpha(3)-integrin subunit by rat alveolar epithelial cells (AECs) grown in primary culture as well as the effects of monoclonal antibodies with blocking activity against the alpha(3)-integrin subunit on AEC monolayer formation. alpha(3)-Integrin subunit mRNA and protein were detectable in AECs on day 1 and increased with time in culture. alpha(3)- and beta(1)-integrin subunits coprecipitated in immunoprecipitation experiments with alpha(3)- and beta(1)-subunit-specific antibodies, consistent with their association as the alpha(3)beta(1)-integrin receptor at the cell membrane. Treatment with blocking anti-alpha(3) monoclonal antibody from day 0 delayed development of transepithelial resistance, reduced transepithelial resistance through day 5 compared with that in untreated AECs, and resulted in large subconfluent patches in monolayers viewed by scanning electron microscopy on day 3. These data indicate that alpha(3)- and beta(1)-integrin subunits are expressed in AEC monolayers where they form the heterodimeric alpha(3)beta(1)-integrin receptor at the cell membrane. Blockade of the alpha(3)-integrin subunit inhibits formation of confluent AEC monolayers. We conclude that the alpha(3)-integrin subunit modulates formation of AEC monolayers by virtue of the key role of the alpha(3)beta(1)-integrin receptor in AEC adhesion.

Animals↗
PubMed1999

Structural correlates for enhanced stability in the E2 DNA-binding domain from bovine papillomavirus.

Papillomaviral E2 proteins participate in viral DNA replication and transcriptional regulation. We have solved the solution structure of the DNA-binding domain of the E2 protein from bovine papillomavirus (BPV-1). The structure calculation used 2222 distance and 158 dihedral angle restraints for the homodimer (202 residues in total), which were derived from homonuclear and heteronuclear multidimensional nuclear magnetic resonance (NMR) spectroscopic data. The root-mean-square deviation for structured regions of the monomer when superimposed to the average is 0.73 +/- 0.10 A for backbone atoms and 1.42 +/- 0.16 A for heavy atoms. The 101 residue construct used in this study (residues 310-410) is about 4.5 kcal/mol more stable than a minimal domain comprising the C-terminal 85 amino acid residues (residues 326-410). The structure of the core domain contained within BPV-1 E2 is similar to the corresponding regions of other papilloma viral E2 proteins. Here, however, the extra N-terminal 16 residues form a flap that covers a cavity at the dimer interface and play a role in DNA binding. Interactions between residues in the N-terminal extension and the core domain correlate with the greater stability of the longer form of the protein relative to the minimal domain.

Animals↗
PubMed1999

Pulmonary veno-occlusive disease.

Pulmonary veno-occlusive disease (PVOD) is a rare cause of pulmonary hypertension that mainly affects children and young adults. Its cause is unknown, although viral infections and drugs have been implicated. Patients with PVOD present with symptoms of right-sided heart failure. Radiologic examination shows prominent pulmonary arteries with Kerley B lines, pleural effusion, and mediastinal adenopathy. The definite diagnosis is made by histologic examination. Eccentric intimal fibrosis and recanalized thrombi in pulmonary veins and venules, arterialized veins, alveolar edema, and medial hypertrophy of arteries are seen on lung biopsy. No effective treatment is available; lung transplantation has been tried. The prognosis associated with PVOD is poor.

Adult↗
PubMed1999

Lung transplantation for cystic fibrosis: an update and practical considerations for referring candidates.

In this article, the authors provide an update to Maurer and Chaparro's 1995 review in this journal of lung transplantation for cystic fibrosis. Bilateral (sequential) cadaver donor transplantation is the usual procedure of choice. The four-year survival rate for adult, all-disease, double-bilateral lung transplantation has improved to 53%. Because of lower [corrected] survival rate among adults, living-donor lobar transplantation should be performed only when cadaver lungs are unlikely to become available. The International Society for Heart and Lung Transplantation and the Cystic Fibrosis Foundation have promulgated uniform guidelines for transplantation candidate selection. Issues of diabetes mellitus, mechanical ventilation, osteoporosis, malnutrition, fungi and drug-resistant bacteria, pleural fibrosis, and sinusitis in relation to transplantation candidacy are discussed. Some practical points regarding transplantation center referral are presented, and a list of cystic fibrosis transplantation centers in the United States is supplied.

Adult↗
PubMed1998

Structure and topography of the membrane-binding C2 domain of factor VIII in the presence of dodecylphosphocholine micelles.

A 21 residue peptide from the C2 domain of the antihaemophilic factor VIII competes with factor VIII for membrane-binding sites in vitro. Here, we provide the structure and topography of the peptide in solution, on dodecylphosphocholine (DPC) micelles, determined using 1H-NMR spectroscopy. The peptide assumes an amphipathic structure comprising an extended N-terminal region and a C-terminal helix. The average root-mean-square deviation is 0.7+/-0.2 A for the superimposition of the backbone atoms of Ile6 to Arg18 on the lowest energy structure. Whereas the backbone conformation is similar to that in SDS micelles, the Trp11 side-chain orientation is dramatically changed. The indole ring is nearly parallel to the peptide backbone in SDS micelles but perpendicular in DPC micelles. Further, pKa values of the two histidines change by more than 1 pH unit in SDS relative to DPC, which localizes the imidazole rings to the interfacial region. Line-broadening induced by spin-labelled phosphatidylcholine shows that most of the amino acid side-chains that penetrate the DPC micelle are hydrophobic. Thus, the long axis of the peptide lies parallel to the micelle surface and the hydrophobic face of the alpha-helix provides hydrophobic membrane interaction. The large chemical shift changes shown by Trp11 and N-terminal amino acid residues in SDS relative to DPC indicate that this region may be involved in membrane phospholipid recognition. 1H-NMR assignments, CD spectra, one-dimensional 1H-NMR spectra, chemical-shift analysis and nuclear Overhauser effect information are reported in Supplementary Publication SUP 50184 (11 pages), which has been deposited at the British Library Document Supply Centre, Boston Spa, Wetherby, West Yorkshire LS23 7BQ, U.K, from whom copies can be obtained according to the terms indicated in Biochem. J. (1997) 321, 8.

Amino Acid Sequence↗
PubMed1998

Constrictive (obliterative) bronchiolitis: diagnosis, etiology, and a critical review of the literature.

Constrictive bronchiolitis (CB) (or obliterative bronchiolitis) designates inflammation and fibrosis occurring predominantly in the walls and contiguous tissues of membranous and respiratory bronchioles, with resultant narrowing of their lumens. It differs from bronchiolitis obliterans-organizing pneumonia in its histopathology and clinical course. Most cases of CB occur in the setting of organ transplants, particularly lung and heart-lung transplants, but also in bone marrow transplants. Other bona fide cases are rare: infection, particularly viral infection, appears to be a well-documented precursor to CB in children, but not in immunocompetent adults. Constrictive bronchiolitis also has been reported in the course of rheumatoid arthritis, in certain other autoimmune diseases such as pemphigus vulgaris, after inhalation of toxic gases such as nitrogen oxide, after ingestion of certain drugs or medicinal agents such as Sauropus androgynous, and as a cryptogenic illness. Recent reports suggest that CB, as defined by clinical criteria (that is, bronchiolitis obliterans syndrome), is very common in lung allograft recipients who survive more than 5 years and, although it is associated with significant mortality, it also can be clinically stable. Furthermore, with the current practice of close monitoring of these patients, it appears that CB may now be diagnosed at an earlier stage, at which resolution, or at least stabilization of progression, is possible. A histopathologic diagnosis of CB in lung transplant and other patients may be difficult to make due to the patchy distribution of lesions, the technical difficulty in obtaining tissue in late lesions with extensive fibrosis, and the failure to recognize lesions. With regard to the last of these, in early stages of disease, CB may be subtle and easily missed in routine hematoxylin-eosin-stained specimens, while in advanced stages the disease may be equally difficult to diagnose if the patchy scarring in the lung is interpreted as nonspecific. The relative loss of bronchioles and the relationship of the scars to contiguous arteries should signal the need for elastic stains to look for the residual elastica of the bronchioles amidst the foci of fibrosis. Increasingly, clinical grounds, including pulmonary functions studies and high-resolution computed tomography findings, are proving to be relatively sensitive methods of detecting CB. Finally, the progressive airway destruction in chronic transplantation rejection appears to be a T-cell-mediated process. The "active" form of constrictive bronchiolitis, with attendant lymphocytic inflammation of the airways, likely precedes the "inactive" or scarred form of constrictive bronchiolitis.

Adult↗
PubMed1998

Parenteral triamcinolone acetonide: an alternative corticosteroid for the treatment of asthma.

Corticosteroids are effective in reducing the airway inflammation and controlling the symptoms of asthma. Many patients with chronic, severe asthma are steroid-dependent, requiring daily oral corticosteroids. Although corticosteroids may be effective, many patients suffer from their intolerable side effects. Various medications have been used as steroid-sparing agents in patients who suffer from the side effects of long-term high-dose steroids. While drugs like methotrexate and cyclosporine are promising, none have clearly been shown to be beneficial in most patients with asthma. The long-acting parenteral steroid triamcinolone acetonide has been tested by various investigators in these patients for over 20 years. Intramuscular triamcinolone appears to beneficial, with no significant increase in adverse effects.

Anti-Asthmatic Agents↗
PubMed1998

Diagnostic pitfalls in asthma.

Asthma is a common disease, diagnosed and treated routinely, that still lacks a clear, universally accepted definition. The diagnosis, made mostly by history and physical diagnosis, is often supported by peak flow rate or spirometric measurements. This time-honored approach may prove to be unreliable, resulting in overdiagnosis of the disease. The literature is replete with reports about patients treated as if they had asthma in whom other pulmonary diseases were eventually diagnosed. The incidence of asthma is increasing; there seems to be a lower threshold now for making this diagnosis. Overdiagnosis can be avoided, however, by systematic evaluation and complete pulmonary function testing. This paper presents two examples of clinical carelessness resulting in diagnostic delay of underlying disorders mimicking bronchial asthma.

Amyotrophic Lateral Sclerosis↗
PubMed1998

Constrictive (obliterative) bronchiolitis.

Constrictive bronchiolitis (CB), also termed in lung transplant patients obliterative bronchiolitis, is inflammation and fibrosis occurring predominantly in the walls and contiguous tissues of membranous and respiratory bronchioles with resultant narrowing of their lumens. CB is found in a variety of settings, most often as a complication of lung and heart-lung transplantation (affecting 34% to 39% of patients, usually in the first 2 years after transplantation) and bone marrow transplantation, but also in rheumatoid arthritis, after inhalation of toxic agents such as nitrogen dioxide, after ingestion of certain drugs such as penicillamine and ingestion of the East Asian vegetable Sauropus androgynous, and as a rare complication of adenovirus, influenza type A, measles, and Mycoplasma pneumoniae infections in children. In lung transplants, CB is the single most important factor leading to death thereafter. In one study, the overall mortality rate was 25%. However, at the same time, 87% of patients who were asymptomatic and diagnosed solely by transbronchial biopsy had resolution or stabilization of disease. Decreases in FEV1 from baseline can be used to clinically support CB in transplant patients; the term bronchiolitis obliterans syndrome is used to denote this clinical dysfunction, and a grading system has been established for it that is now widely used in the literature. Significant risk factors for the development of CB in lung transplants include alloantigen-dependent and -independent mechanisms. In the former group are late acute rejection and HLA mismatches at the A loci; in the latter are ischemia/reperfusion injuries to airways that result from the transplantation surgery and cytomegalovirus infection.

Biopsy↗
PubMed1998

Progressive systemic sclerosis and the lung.

Pulmonary manifestations of systemic sclerosis (scleroderma) are many. The mean survival in these patients is 78 +/- 17 months. Improved diagnostic techniques and better therapeutic options are essential to stem the tide of overwhelming mortality in patients with scleroderma lung disease.

Diagnostic Imaging↗
PubMed1997

Effect of prolyl isomerase on the folding reactions of staphylococcal nuclease.

The low-temperature fluorescence-detected refolding of staphylococcal nuclease (SNase) can be described by three slow kinetic phases. The slowest phase is absent in the P117G mutant of SNase. Peptidyl prolyl cis-trans isomerase (cyclophilin), which has been shown to catalyze the slow folding reactions of some proteins, was employed to determine which of the refolding reactions of SNase and P117G SNase involve proline isomerization. We report here that all three folding phases of the wild type and the slower phase of P117G SNase are catalyzed by prolyl isomerase, indicating that proline isomerization is involved in these fluorescence-detected phases in the refolding of SNase. Since the rates of these phases are denaturant-dependent, we conclude that the slow folding steps involve isomerization of non-native cis proline peptide bonds and are tightly coupled to denaturant-sensitive structural changes.

Catalysis↗
PubMed1996

Autocatalyzed protein folding.

Proline isomerization, an intrinsically slow process, kinetically traps intermediates in slow protein folding reactions. Thus, enzymes that catalyze proline isomerization (prolyl isomerases) often catalyze protein folding. We have investigated the folding kinetics of FKBP, a prolyl isomerase. The main conclusion is that FKBP catalyzes its own folding. Altogether, the FKBP refolding kinetics are resolved into three exponential phases: a fast phase, tau 3; an intermediate phase, tau 2; and a slow phase, tau 1. Unfolding occurs in a single phase, the unfolding branch of phase tau 2. In the presence of native FKBP, both the intermediate (tau 2) and slow (tau 1) phases are faster, suggesting that folding phases tau 1 and tau 2 involve proline cis-trans isomerization. In the absence of added native FKBP, autocatalytic folding of FKBP is detected. For refolding starting with all the FKBP unfolded initially, the slowest folding phase (tau 1) is almost 2-fold faster at a final concentration of 14 microM FKBP than at 2 microM FKBP, suggesting that catalytically active FKBP formed in the fast (tau 3) or intermediate (tau 2) folding phases catalyzes the slow folding phase (tau 1). Moreover, autocatalysis of folding is inhibited by FK506, an inhibitor of the FKBP prolyl isomerase activity. The results show that the slow phase in FKBP folding is an autocatalyzed formation of native FKBP from kinetically trapped species with non-native proline isomers. While the magnitude of the catalytic effects reported here are modest, FKBP folding may provide a prototype for autocatalysis of kinetically trapped macromolecular conformational changes in other systems.

Amino Acid Isomerases↗
PubMed1995

Prolyl isomerase as a probe of stability of slow-folding intermediates.

Catalysis of slow folding reactions by peptidyl prolyl cis-trans isomerase (PPI) provides estimates of stabilities of intermediates in folding of normal and mutational variants of yeast iso-2 cytochrome c. A two-state model postulating a rapid preequilibration of intermediates with the unfolded protein is employed to calculate the stabilization free energy of the intermediate from the catalytic efficiency (kcat/Km) of PPI toward slow folding species. Stability measurements have been made for two distinct slow-folding intermediates: the absorbance-detected (IIS) and fluorescence-detected (IIIS) intermediates. Mutation-induced changes in the stability of the intermediates and in the activation free energy for slow folding are compared to changes in equilibrium thermodynamic stability. The results show that (1) for iso-2 the absorbance-detected intermediates (IIS) are slightly more stable than the fluorescence-detected intermediates (IIIS), (2) most mutations have different effects on equilibrium stability and the stability of the IIS or IIIS intermediates, and (3) for both slow folding reactions the mutation-induced changes in the activation free energy are small compared to the magnitude of the activation free energy barrier. Differential effects of mutations on equilibrium stability and the stability of intermediates provides a means of assessing the sequence-encoded structural specificity for folding. Mutations with different effects on intermediate stability and equilibrium stability change the encoded folding information and may alter folding pathways and/or lead to different three-dimensional structures. Identification of mutations which stabilize a folding intermediate relative to the native conformation provides an empirical approach to the design of thermodynamically stable forms of folding intermediates.

Amino Acid Isomerases↗