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Biomedical subjects

S V Nair

Publications and source records attributed to S V Nair.

11 recordsLinked to original sources
PubMed2006

Myocardial iron loading in patients with thalassemia major on deferoxamine chelation.

BACKGROUND: Heart failure secondary to myocardial iron loading remains the leading cause of death in thalassemia major (TM). We used cardiovascular magnetic resonance (CMR) to assess the prevalence of myocardial iron overload and ventricular dysfunction in a large cohort of TM patients maintained on conventional chelation treatment with deferoxamine. METHODS: A mobile CMR scanner was transported from London, UK, to Sardinia, Italy where 167 TM patients were assessed for myocardial iron loading, B-natriuretic peptide (BNP), and ferritin. In patients with myocardial iron loading CMR assessments of ventricular function were also made. RESULTS: Myocardial iron loading (T2* < 20 ms) was present in 108 (65%) patients, which was severe (T2* < 8 ms) in 22 (13%). Impaired (< 56%) left ventricular (LV) ejection fraction (EF) was present in 5%, 20% and 62% of patients with mild, moderate or severe iron loading. Increasing myocardial iron was related to impaired LVEF (Rs = 0.57, p < 0.001), weakly related to serum ferritin (Rs = -0.34, p < 0.001), and not related to liver iron (Rs = 0.11, p = 0.26). BNP was weakly related to myocardial iron (Rs = -0.35, p < 0.001) and was abnormal in only 5 patients. CONCLUSIONS: Myocardial siderosis was found in two-thirds of thalassemia major patients on maintenance deferoxamine treatment. This was combined with a high prevalence of impaired LV function, the severity of which tracked the severity of iron deposition. BNP was not useful to assess myocardial siderosis.

Cardiomyopathies↗
PubMed2002

A complement component C3-like protein from the tunicate, Styela plicata.

This study identifies a complement component C3-like protein in the solitary tunicate, Styela plicata. Three different polyclonal antibodies raised against C3 molecules from two species (humans and the tunicate, Halocynthia roretzi) were used to identify the C3-like protein in S. plicata hemolymph. The C3 cross-reactive protein is a 170kDa heterodimer composed of polypeptides (116 and 80kDa) that have molecular weights comparable to those of C3alpha and C3beta from other species. Amino acid sequencing and amino acid composition analysis confirmed that the C3-like protein from S. plicata is closely related to C3 from H. roretzi.

Amino Acid Sequence↗
PubMed2001

Effects of tributyltin and other metals on the phenoloxidase activating system of the tunicate, Styela plicata.

Toxic metals, such as tributyltin (TBT), contribute substantially to anthropogenic pollution in many estuarine environments. Animals that live in those environments, particularly invertebrate filter feeders like tunicates, are likely to be exposed to substantial metal contamination. This study investigates the effects of TBT and other metals on the phenoloxidase activity of the estuarine tunicate, Styela plicata, in an effort to identify a biochemical marker of metal pollution. Hemocytes harvested from S. plicata that were exposed to tributyltin or copper in aquaria had significantly enhanced phenoloxidase activities relative to non-exposed controls. This enhanced phenoloxidase activity could be explained by an increased frequency of morula cells, which contain high levels of phenoloxidase's proenzyme, prophenoloxidase. Unlike those from tunicates exposed to metals in aquaria, the phenoloxidase activities of hemocytes incubated with tributyltin in vitro were significantly reduced when compared with hemocytes cultured without tributyltin. The ability of tributyltin to decrease phenoloxidase activity in tissue culture may reflect its known inhibitory effects on calcium-dependent signaling systems such as those involved in the exocytosis of prophenoloxidase from morula cells.

Animals↗
PubMed2001

A C-type lectin from the tunicate, Styela plicata, that modulates cellular activity.

Previous studies have identified proteins from tunicates (invertebrate members of the Phylum Chordata) that have physicochemical and functional properties similar to those of the inflammatory cytokine, interleukin 1 (IL-1). Here we characterize one of those proteins from the tunicate, Styela plicata, that can stimulate tunicate and mammalian cell proliferation, activate phagocytosis, increase interleukin 2 (IL-2) secretion by mammalian peripheral blood mononuclear cells and enhance IL-2 receptor (IL-2R) expression by mammalian EL-4.IL-2 cells. Partial amino acid sequence data showed that the S. plicata protein resembles three C-type lectins (TC14, TC14-1 and TC14-2) from a closely related tunicate species, Polyandrocarpa misakiensis. Its similarity to carbohydrate recognition domains (CRDs) from P. misakiensis lectins suggests that the S. plicata protein modulates the activities of mammalian immunocompetent cells by interacting with carbohydrate moieties of glycosylated cell surface receptors.

Amino Acid Sequence↗
PubMed2000

A collectin-like protein from tunicates.

Collectins are a sub-family of C-type lectins from mammals and birds that are characterized by their collagen-like domains. The mammalian collectin, mannose binding lectin, has attracted considerable interest because it can activate complement components via a lectin-mediated complement pathway that is independent of immunoglobulins. In this study, we have identified a calcium-dependent lectin from the invertebrate (tunicate), Styela plicata, that bears substantial similarities to mammalian collectins. The tunicate lectin, which was isolated by carbohydrate affinity chromatography, has a reduced apparent molecular mass of 43 kDa. The 43 kDa reduced polypeptide appeared as dimers, trimers and hexamers when analyzed by non-reducing and two-dimensional sodium dodecyl sulfate-polyacrylamide gel electrophoresis, while gel filtration suggested that the native form of the protein was a nonamer. Amino acid sequence and amino acid composition analysis revealed obvious similarities between the tunicate lectin and mammalian collectins, notably the inclusion of a collagenous domain and a short, cysteine bearing N-terminal domain. The identification of a collectin-like protein in an invertebrate such as S. plicata, which does not express immunoglobulin, indicates that lectin-mediated complement pathways may predate the origin of antibodies.

Amino Acid Sequence↗
PubMed1995

Immunization with glycoprotein C of equine herpesvirus-1 is associated with accelerated virus clearance in a murine model.

The glycoprotein C (gC) gene of equine herpesvirus-1 (EHV-1) was expressed in insect cells by a recombinant baculovirus as several products with apparent molecular weights of 66 kDa-80 kDa. The baculovirus EHV-1 gC products were recognised by monoclonal antibody and by EHV-1 convalescent equine sera, indicating conservation of antigenic determinants and confirming this glycoprotein as a target for the equine immune system. Mice immunized with recombinant EHV-1 gC showed accelerated clearance of EHV-1 from respiratory tissues following intranasal challenge. Virus clearance was accompanied by virus specific antibodies and by cell mediated immune responses measured by a delayed type hypersensitivity reaction and lymphocyte stimulation by killed EHV-1 as antigen.

Animals↗
PubMed1976

Beclomethasone dipropionate aerosol in the treatment of steroid-dependent asthma. A 12-week double-blind study comparing beclomethasone dipropionate and a vehicle aerosol.

In a randomized double-blind 12-week trial of steroid-dependent patients with chronic asthma, ten (59 percent) out of 17 patients receiving beclomethasone dipropionate aerosol in a total daily dose of 400mug were able to discontinue systemic corticosteroid therapy successfully, compared to two (13 percent) out of 15 patients in the placebo group (P=0.002). At the end of the trial, the average 8 am plasma cortisol level in the group receiving beclomethasone was more than twice the pretherapy value, whereas the level in the placebo group showed no significant change. There was no significant difference between the beclomethasone group and the placebo group in the overall incidence of side effects related to the aerosol and the effects of systemic corticosteroid withdrawal. Oral candidiasis was not found in any patient receiving beclomethasone dipropionate aerosol. Allergic nasal symptoms were disabling in many patients when the oral dosage of corticosteroids was tapered.

Administration, Oral↗
PubMedDate not supplied

Humoral opsonins of the tunicate, Pyura stolonifera.

This study characterizes humoral opsonins from the tunicate, Pyura stolonifera. The predominant opsonic components in P. stolonifera hemolymph were found to be calcium-dependent lectins with broad carbohydrate specificities. The opsonic lectins were purified by carbohydrate affinity chromatography which eluted a complex pattern of proteins ranging in molecular mass from 80 to >200kDa. Reducing and two dimensional SDS-PAGE indicated that the diversity of mature lectins evident under non-reducing conditions resulted from the differential oligomerization of two polypeptide sub-units (35 and 22kDa). In addition to lectin-mediated opsonic activity, hemolymph was also found to contain proteolytically activated opsonins. These data suggest that multiple, possibly interactive opsonic systems co-exist in P. stolonifera.

Animals↗
PubMedDate not supplied

Light and electron microscopic observations of blastomyces dermatitidis in sputum.

Freshly expectorated sputum from a 52-year-old man with extensive pulmonary blastomycosis was examined by light and electron microscopy. Wet preparations of the sputum, stained with 1% aqueous cresyl violet, revealed numerous thick-walled, spherical blastospores and occasional budding forms. Ultrastructurally, the blastospores revealed a double-layered cell wall, the peripheral portion of which consisted of a thick, densely staining lamellar material of variable thickness, suggestive of the glycocalyx of bacterial cells. Mitochrondria and other organelles were easily recognized, but distinct nuclei were not observed. Retraction of the cell membrane and cytoplasmic mass from the cell wall was a common finding. Results of this case study suggest that electron microscopy of sputum may serve as an important adjunct to conventional staining techniques for the presumptive diagnosis of blastomycosis. Similar studies of other fungi in respiratory tract secretions may be helpful in providing more precise morphologic identification.

Blastomyces↗