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Biomedical subjects

S Sivakumar

Publications and source records attributed to S Sivakumar.

35 records · Page 2Linked to original sources
PubMed2003

Detection of egg drop syndrome virus antigen or genome by enzyme-linked immunosorbent assay or polymerase chain reaction.

Mouse monoclonal antibodies (mAbs) were produced against an Indian isolate of egg drop syndrome (EDS) virus and characterized. Four hybridoma clones were secreting mAbs that bound to a 100 kDa protein, presumably the hexon protein. These mAbs were found to cross-react with two other Indian isolates of EDS virus and to the reference UK 127 strain. Three of these mAbs were mapped to the same epitope compared with the other mAb (F8), which bound to a different epitope. An antigen-capture enzyme-linked immunosorbent assay (AC-ELISA) was developed using the F8 mAbs as capture antibody and polyclonal chicken serum against EDS virus as detection antibody. A polymerase chain reaction (PCR) was used to detect the EDS viral genome. Following experimental infection of oestrogen-treated chickens with EDS virus, cloacal swabs, oviduct, uterus and spleen were collected at different days post-infection and used in both AC-ELISA and PCR, directly and after a single passage in embryonated duck eggs. The sensitivity and specificity of antigen detection by AC-ELISA or PCR was 95% and 98%, respectively. For diagnosis of EDS viral infections, PCR is recommended due to its ease and the lack of requirement of prepared reagents such as mAbs or conjugates. We recommend that PCR be performed directly on boiled tissue homogenates. Any negative samples may be passaged in embryonated duck eggs and the allantoic fluids tested by PCR before a conclusive negative diagnosis is given.

Adenoviridae Infections↗
PubMed2002

Silencing of midgut aminopeptidase N of Spodoptera litura by double-stranded RNA establishes its role as Bacillus thuringiensis toxin receptor.

Insecticidal crystal proteins of Bacillus thuringiensis bind to receptors in the midgut of susceptible insects leading to pore formation and death of the insect. The identity of the receptor is not clearly established. Recently a direct interaction between a cloned and heterologously expressed aminopeptidase (slapn) from Spodoptera litura and the Cry1C protein was demonstrated by immunofluorescence and in vitro ligand blot interaction. Here we show that administration of slapn double-stranded RNA to S. litura larvae reduces its expression. As a consequence of the reduced expression, a corresponding decrease in the sensitivity of these larvae to Cry1C toxin was observed. The gene silencing was retained during the insect's moulting and development and transmitted to the subsequent generation albeit with a reduced effect. These results directly implicate larval midgut aminopeptidase N as receptor for Bacillus thuringiensis insecticidal proteins.

Animals↗
PubMed2002

Bis[1-(pyridin-2-yl)ethanone-kappa N 4-phenylthiosemicarbazonato-kappa 2N4,S]manganese(II).

One half of the molecule of the title complex, [Mn(C(14)H(13)N(4)S)(2)], is related to the other half by a twofold axis passing through the Mn atom. This high-spin Mn atom is six-coordinated, in an octahedral geometry, by the azomethine N, the pyridyl N and the thiolate S atom of two planar 1-(pyridin-2-yl)ethanone N(4)-phenylthiosemicarbazone ligands. In the crystal, the molecules are interconnected by N-H.S and C-H.N interactions, forming a three-dimensional network.

Journal Article↗
PubMed2002

Profile of transfusion transmissible infections and associated risk factors among blood donors of Kerala.

Blood transfusion is an important mode of transmission of infections to the recipient. The aim of the study was to assess the prevalence of transfusion transmissible infections and the possible risk factors among blood donors. During the study period (1994-99) donor samples were screened for HBsAg, HIV, HCV and Syphilis. The relevant donor history was examined to identify the risk factors leading to transfusion transmissible infections. The prevalence of infection was 3.1% among donors, with HBsAg constituting 1.3%, HCV 1.4%, HIV 0.2% and RPR 0.2%. In a classification based on occupation, class III donors (drivers, Businessmen & men in uniform) showed a significantly higher incidence of transfusion transmissible infections for HIV (0.38%) and Syphilis (0.36%). Health care workers constituted only a small fraction of the study; prevalence of infections was low among them. History of jaundice or hospitalization was not associated with higher incidence of seropositivity. Seropositivity for HIV is relatively low compared to similar studies conducted in other regions of the country. This finding is attributed to the pre donation counseling in donor selection. An important outcome of the study is that Class III donors form a high-risk group for transfusion transmissible infections.

Adult↗
PubMed2001

New methods of resolution and purification of racemic and diastereomeric amino alcohol derivatives using boric acid and chiral 1,1'-bi-2-naphthol.

Resolution of the racemic amino alcohol derivatives 1-6 is readily achieved to obtain enantiomerically enriched compounds using chiral 1,1'-bi-2-naphthol and boric acid in solvents such as CH(3)CN, THF, and MeOH. Purification of the diastereomeric mixture 7 has also been carried out following this method. The corresponding intermediate ammonium borate complexes were also characterized by X-ray diffraction methods.

Journal Article↗
PubMed2001

Carbon from Cassava peel, an agricultural waste, as an adsorbent in the removal of dyes and metal ions from aqueous solution.

Cassava (Manihot esculenta) is a short lived erect perennial shrub, planted vegetatively from hard wood stem cuttings. It is an important crop across a wide range of tropical environments and is a significant component of cropping systems. Cassava peel is an agricultural waste from the food processing industry. Activated carbons prepared from waste cassava peel employing physical and chemical methods were tested for their efficiency in the removal of dyes and metal ions from aqueous solution. While both of these were efficient as adsorbents for dyes and metal ions, the material impregnated with H3PO4 showed higher efficiency than the heat treated materials.

Adsorption↗
PubMed2001

Evaluation of a disposable prism for applanation tonometry.

BACKGROUND: Recently the Medical Devices Agency recommended that 'ophthalmic devices that touch the surface of the eye should be restricted to single use'. AIM: To evaluate one such device: a disposable tonometer prism for routine applanation tonometry. METHODS: The intraocular pressure (IOP) of 100 consecutive patients from a general eye clinic (197 eyes) was measured with both a disposable and the standard Goldmann tonometer (Goldmann). The level of agreement between the two methods of clinical measurement was assessed and the sensitivity and specificity of the disposable prism in detecting clinically significant raised IOP estimated. RESULTS: The mean difference in IOP measured by the two different prisms was 0.44 mmHg with a standard deviation (SD) of 1.54. The mean IOP for the disposable prism was 19.51 mmHg (SD 6.53 mmHg). The mean IOP for the standard Goldmann tonometer prism was 19.07 mmHg (SD 6.64 mmHg). The sensitivity to detect IOP > 21 mmHg was 95.9% (95% confidence interval (CI): 86.0-99.5%) and the specificity of 93.9% (95% CI: 88.8-97.2%). It gave a positive predictive value of 83.9% (95% CI: 71.7-92.4%). CONCLUSION: There was close agreement between the IOP measurements obtained by the disposable tonometer prism and the Goldmann device for high and low pressures. If replicated, the high sensitivity and specificity would justify its use in screening.

Adult↗
PubMed2001

Knee crepitus from an unusual source.

A case report of a missed appendicitis presenting with abdominal wall necrotising fasciitis which extended up to the right knee. This subcutaneous collection in the prepatella region of the right knee presented as a crepitus and mimicked an intraarticular pathology.

Aged↗
PubMed2000

An entomological field evaluation of larval biology of sandfly in Kala-azar endemic focus of Bihar--exploration of larval control tool.

Knowing the exact breeding places inside the habitat is very important to plan the larval control strategy. Information regarding larval biology in relation to different seasons will be more useful to organize insecticide spray schedule at a particular month of maximum immature density to bring down the adult sandfly density. In the present study, maximum number of soil samples were found positive in the month of January and minimum in the month of September. Maximum positive soil samples were collected from cattle sheds, minimum in mixed dwellings and in case of human dwellings all soil samples were negative. Comparison of two methods for the isolation of immature stages showed that direct microscopic observation is superior to sugar flotation technique.

Animals↗
PubMed1999

Surgical treatment of endocrine hypertension experience in India.

Between 1980 and 1994, 162 cases of endocrine based hypertension were diagnosed and treated surgically. Seventy-nine cases (48.7%) of phaeochromocytoma, 63 cases (38.8%) of Cushing's syndrome, and 20 cases (12.3%) of Conn's syndrome were diagnosed. In phaeochromocytoma 75% of the tumours arose from the adrenal glands and 25% arose from the extra-adrenal sites. Cushing's syndrome was caused by adenoma (45%), diffuse bilateral adrenal hyperplasia (36%), pigmented macronodular hyperplasia (9%), and adrenal carcinoma (10%). The most common cause of Conn's syndrome was adenoma (95%) which arose mainly from the left adrenal gland (60%). In the present series the success rate of surgical treatment was 100% for phaeochromocytoma, 90% for Cushing's syndrome and 96% for Conn's syndrome. Trucut biopsy of the kidneys of these patients showed hypertensive changes, the moderate hypertension could be due to renal damage.

Adrenal Gland Neoplasms↗
PubMed1998

Secretory protein expression patterns during rat parotid gland development.

The rat parotid gland produces a number of well-characterized secretory proteins. Relatively little is known, however, about the onset of their synthesis and cellular localization during gland development. Secretory protein expression was studied in parotid glands of fetal and postnatal rats using light and electron microscopic immunocytochemistry and Northern blotting. Amylase, parotid secretory protein (PSP), common salivary protein-1 (CSP-1), and SMGB were first detected by immunofluorescence in parotid glands of 18 day fetuses. By 5 days after birth, light and electron microscopic immunolabeling localized all of these proteins to the secretory granules of developing acinar cells. Labeling of acinar cells for DNAse I, however, was not observed until 18 days after birth. Between 9 and 25 days, CSP-1 and SMGB reactivity of acinar cells declined, but increased in intercalated duct cells. After 25 days, CSP-1 and SMGB were found only in intercalated ducts, and amylase, PSP, and DNAse I were restricted to acinar cells. Levels of CSP-1 and SMGB mRNA were relatively constant through 21 postnatal days, but declined significantly after that. Amylase and PSP mRNA increased rapidly and continuously from five days after birth to the adult stage. In contrast, DNAse I mRNA was not detectable until 18 days after birth. The immunocytochemical and molecular analyses define three basic patterns of protein expression in the rat parotid gland: proteins whose synthesis is initiated early in development and is maintained in the acinar cells, such as amylase and PSP; proteins that are initially synthesized by immature acinar cells but are restricted to intercalated ducts in the adult gland, such as CSP-1 and SMGB; and proteins that are synthesized only by mature acinar cells and first appear during the third postnatal week, such as DNAse I. The parotid gland exhibits four distinct developmental stages: prenatal, from initiation of the gland rudiment until birth; neonatal, from 1 day up to about 9 days postnatal; transitional, from 9 days to 25 days of age; and adult, from 25 days on. Although differences exist in timing and in the specific proteins expressed, these developmental stages are similar to those seen in the rat submandibular gland. Additionally, the results support the suggestion that intercalated ducts may differentiate from the neonatal acini.

Age Factors↗
PubMed1996

Immunocytochemical studies of cell differentiation during rat salivary gland development.

The development of the rat submandibular and parotid glands has been studied using antibodies to secretory proteins as cell-specific markers. Although the morphology of the glands and the timing of the main steps of cytodifferentiation are substantially different, they have several proteins and developmental features in common. The latter include the initial formation of perinatal acini which undergo a transition to adult acini expressing a different complement of secretory proteins; the development of adult intercalated ducts (ID) from the perinatal acinar cells; and the retention of the perinatal phenotype in some cells of the ID.

Animals↗
PubMedDate not supplied

Naked plasmid-mediated gene transfer to skeletal muscle ameliorates diabetes mellitus.

BACKGROUND: The ability of tissues to take up naked plasmid DNA in vivo suggests an approach for reconstituting systemic metabolic deficiencies without the disadvantages of viral vectors and lipid-DNA complexes. Plasmid-mediated gene transfer into skeletal muscle was investigated as a means of providing a therapeutic source of insulin. METHODS: Four plasmid constructs, each bearing a mouse furin cDNA transgene and rat proinsulin cDNA (modified for processing by furin) driven by four different promoters were injected into the calf muscles of male Balb/c mice. Insulin and C-peptide concentrations were measured by radio-immunoassays having minimal crossreactivity for proinsulin and partially processed proinsulin. RESULTS: Intramuscular insulin concentrations increased by up to 3.6-fold over controls seven days after single injections of CMV, beta-actin, hsp70 and myoglobin promoter constructs. The optimal dose for most constructs was 100 micrograms plasmid DNA. Intramuscular plasmid injection into streptozotocin-induced diabetic Balb/c mice raised plasma insulin and C-peptide concentrations, and reduced hyperglycaemia. Two injections (100 micrograms plasmid DNA each) caused higher plasma insulin concentrations and significantly reduced hyperglycemia in diabetic mice than a single injection. Best results were obtained when plasmid injections preceded induction of diabetes by 14 days. CONCLUSIONS: Skeletal muscle is a potentially useful platform for ectopic secretion of insulin using naked plasmid as a gene transfer vector. Injection at two sites 14 days before the onset of severe hyperglycemia is optimal. This approach could protect Type I diabetics from fatal ketoacidosis and enhance the action of agents that sensitize tissues to insulin in type II diabetes.

Animals↗