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Biomedical subjects

M Srinivasan

Publications and source records attributed to M Srinivasan.

At least 37 records · Page 2Linked to original sources
PubMed2005

Seasonal distribution of physico- chemical parameters in effluent discharge area of Uppanar estuary, Cuddalore, south-east coast of India.

Seasonal distribution of physico-chemical characteristics such as rainfall, pH, salinity, temperature, light extinction coefficient, dissolved oxygen, biological oxygen demand and nutrients like total phosphorus, inorganic phosphate, nitrite, nitrate and reactive silicate has been studied at two stations of Uppanar estuary in relation to effluent discharges from SIPCOT industries. There are 44 industries discharges their effluents into Uppanar estuary, which may influence the biota. Nutrient concentrations were higher during monsoon season and low during summer season. The mean concentrations of nutrients were high at station 1 than station 2 due to discharges from industries, coconut husk retting grounds near the station 1. In the present study, the physico-chemical characteristic of Uppanar estuary carried out and variations are discussed.

Agriculture↗
PubMed2004

A(1,3)-strain mediated epimerization of 2e,3e,5e,6e-tetraarylpiperidin-4-one oximes.

A series of tri- and tetraarylpiperidin-4-one oximes were synthesized from 2e,3e,6e-tri- and 2e,3e,5e,6e-tetraarylpiperidin-4-ones, respectively. In the case of the latter compounds, oximation is accompanied by epimerization at C-5 to avoid the A(1,3)-strain between the oxime OH group and the 5e-aryl ring of the initially formed oxime resulting in 2e,3e,5a,6e-tetraarylpiperidin-4-one oximes. 1H, 13C and 2D NMR spectroscopic data were employed to characterize and investigate the stereochemistry of these compounds.

Anti-Infective Agents↗
PubMed2004

Rhizosphere bacterial signalling: a love parade beneath our feet.

Plant roots support the growth and activities of a wide variety of microorganisms that may have a profound effect on the growth and/or health of plants. Among these microorganisms, a high diversity of bacteria have been identified and categorized as deleterious, beneficial, or neutral with respect to the plant. The beneficial bacteria, termed plant growth-promoting rhizobacteria (PGPR), are widely studied by microbiologists and agronomists because of their potential in plant production. Azospirillum, a genus of versatile PGPR, is able to enhance the plant growth and yield of a wide range of economically important crops in different soils and climatic regions. Plant beneficial effects of Azospirillum have mainly been attributed to the production of phytohormones, nitrate reduction, and nitrogen fixation, which have been subject of extensive research throughout the years. These elaborate studies made Azospirillum one of the best-characterized genera of PGPR. However, the genetic and molecular determinants involved in the initial interaction between Azospirillum and plant roots are not yet fully understood. This review will mainly highlight the current knowledge on Azospirillum plant root interactions, in the context of preceding and ongoing research on the association between plants and plant growth-promoting rhizobacteria.

Azospirillum↗
PubMed2004

Fixed dilated pupil (Urrets-Zavalia syndrome) in corneal dystrophies.

PURPOSE: To report fixed dilated pupil following penetrating keratoplasty for corneal dystrophies. METHODS: Retrospective chart analysis of subjects who underwent penetrating keratoplasty for corneal dystrophies between 1998 and 2002 at our institute. RESULTS: Three of the subjects with fixed dilated pupils after penetrating keratoplasty had Macular corneal dystrophy and one subject had Fuchs Endothelial dystrophy. Fixed dilated pupils were noticed in the immediate postoperative period. None of the subjects had evidence for glaucoma either pre- or postoperatively. The follow up period ranged from 5 to 18 months. CONCLUSIONS: Fixed dilated pupil (Urrets-Zavalia syndrome) can occur after penetrating keratoplasty for corneal dystrophies and may not be limited to eyes with keratoconus as previously reported.

Adult↗
PubMed2004

Fungal keratitis.

PURPOSE OF REVIEW: Throughout the world, fungal keratitis is a leading cause of ocular morbidity. The purpose of this review is to discuss the recently published literature in relation to the epidemiology, etiology, diagnosis, and therapy of fungal keratitis. RECENT FINDINGS: Globally, the incidence of keratomycoses and systemic mycoses is rising. Current therapies are often ineffective. Ongoing research toward rapid diagnosis and specific drug therapy could minimize the morbidity caused by this preventable disease. New antifungal drugs, including voriconazole, have been applied recently for the treatment of keratomycosis. SUMMARY: The incidence of fungal keratitis is on the rise in the densely populated continents of Asia and Africa. Filamentous fungi are the most frequently reported pathogens. Polyene antifungal antibiotics, the first-line therapy in fungal keratitis, are not effective in severe keratomycosis. Imidazole derivatives such as voriconazole and echinocandin may be the better choice in the future.

Administration, Topical↗
PubMed2004

Issues in temperamental unsuitability re-examining concepts and current practice in the British Army.

Currently, in the UK military, and particularly in the Army, a significant number of personnel are regularly discharged on the grounds of being assessed as "Temperamentally Unsuitable (TU) for military duties", under Queen's Regulations (QRs): (Army) 9.414 and 9.434 (1). In the last two years (2001--2003), preliminary figures suggest that approximately 700 serving personnel were recommended for discharge under this category by only four psychiatrists in the south of England. The regulations governing TU have been in existence and essentially unchanged since their development long before the 1960s albeit subject to parliamentary quinquennial review. The Army General and Administrative Instructions (AGAI) (2) standards also remain unchanged over this period. This paper raises questions about the current validity and relevance of existing TU concepts and regulations with suggestions as to what is being proposed in the context of changing roles, technology and advances in the modern armed forces.

Affective Symptoms↗
PubMed2003

Corneal blindness: a global perspective.

Diseases affecting the cornea are a major cause of blindness worldwide, second only to cataract in overall importance. The epidemiology of corneal blindness is complicated and encompasses a wide variety of infectious and inflammatory eye diseses that cause corneal scarring, which ultimately leads to functional blindness. In addition, the prevalence of corneal disease varies from country to country and even from one population to another. While cataract is responsible for nearly 20 million of the 45 million blind people in the world, the next major cause is trachoma which blinds 4.9 million individuals, mainly as a result of corneal scarring and vascularization. Ocular trauma and corneal ulceration are significant causes of corneal blindness that are often underreported but may be responsible for 1.5-2.0 million new cases of monocular blindness every year. Causes of childhood blindness (about 1.5 million worldwide with 5 million visually disabled) include xerophthalmia (350,000 cases annually), ophthalmia neonatorum, and less frequently seen ocular diseases such as herpes simplex virus infections and vernal keratoconjunctivitis. Even though the control of onchocerciasis and leprosy are public health success stories, these diseases are still significant causes of blindness--affecting a quarter of a million individuals each. Traditional eye medicines have also been implicated as a major risk factor in the current epidemic of corneal ulceration in developing countries. Because of the difficulty of treating corneal blindness once it has occurred, public health prevention programmes are the most cost-effective means of decreasing the global burden of corneal blindness.

Blindness↗
PubMed2003

Novel mutations in the CHST6 gene associated with macular corneal dystrophy in southern India.

OBJECTIVE: To further characterize the role of the carbohydrate sulfotransferase (CHST6) gene in macular corneal dystrophy (MCD) through identification of causative mutations in a cohort of affected patients from southern India. METHODS: Genomic DNA was extracted from buccal epithelium of 75 patients (51 families) with MCD, 33 unaffected relatives, and 48 healthy volunteers. The coding region of the CHST6 gene was evaluated by means of polymerase chain reaction amplification and direct sequencing. Subtyping of MCD into types I and II was performed by measuring serum levels of antigenic keratan sulfate. RESULTS: Seventy patients were classified as having type I MCD, and 5 patients as having type II MCD. Analysis of the CHST6 coding region in patients with type I MCD identified 11 homozygous missense mutations (Leu22Arg, His42Tyr, Arg50Cys, Arg50Leu, Ser53Leu, Arg97Pro, Cys102Tyr, Arg127Cys, Arg205Gln, His249Pro, and Glu274Lys), 2 compound heterozygous missense mutations (Arg93His and Ala206Thr), 5 homozygous deletion mutations (delCG707-708, delC890, delA1237, del1748-1770, and delORF), and 2 homozygous replacement mutations (ACCTAC 1273 GGT, and GCG 1304 AT). One patient with type II MCD was heterozygous for the C890 deletion mutation, whereas 4 possessed no CHST6 coding region mutations. CONCLUSION: A variety of previously unreported mutations in the coding region of the CHST6 gene are associated with type I MCD in a cohort of patients in southern India. CLINICAL RELEVANCE: An improved understanding of the genetic basis of MCD allows for earlier, more accurate diagnosis of affected individuals, and may provide the foundation for the development of novel disease treatments.

Corneal Dystrophies, Hereditary↗
PubMed2003

A randomised clinical trial comparing 2% econazole and 5% natamycin for the treatment of fungal keratitis.

AIM: To compare 2% econazole and 5% natamycin in the management of fungal keratitis. METHODS: A randomised clinical trial was performed using 2% econazole or 5% natamycin as the two treatment arms on patients presenting with culture positive fungal keratitis to the cornea service at Aravind Eye Care System, Madurai, India. RESULTS: 116 patients were recruited, and 112 continued in the study. There were no significant differences between the two arms at baseline or for success (defined as a healed or healing ulcer) at final visit (p = 0.79). CONCLUSIONS: 2% Econazole appears to be as effective as 5% natamycin for the management of fungal keratitis.

Adolescent↗
PubMed2002

Effects of added plasmin on the formation and rheological properties of rennet-induced skim milk gels.

Elevated plasmin enzyme activity has been suggested as a likely cause of impaired functional properties that occur in milk from cows either in their late-lactational period or that are experiencing mastitis. However, there are conflicting reports on the impact of plasmin on rennet coagulation properties of milk. The effects of added plasmin on the rheological properties, at small and large deformation, of rennet-induced gels were investigated. The microstructure of rennet-induced gels was studied, using confocal scanning laser microscopy. Porcine plasmin was added to reconstituted milk, and samples were incubated at 37 degrees C for between 0.5 to 8 h. The hydrolysis reaction was terminated using soybean trypsin inhibitor. The extent of degradation of caseins was determined with SDS-PAGE. The extent of breakdown of alpha(s)- and beta-caseins increased with incubation time with plasmin. Storage modulus of rennet gels decreased linearly with increasing degradation of caseins. There was an increase in the loss tangent parameter of the gels with increasing casein degradation, indicating a more liquid-like gel character. Gelation time decreased until approximately 3 h of incubation with plasmin (when the amounts of intact alpha(s)- and beta-caseins were approximately 46 and 50%, respectively); thereafter, gelation time increased considerably. Yield stress of rennet-induced gels decreased with increasing casein breakdown. When the level of casein hydrolysis was high (<40% of intact caseins), the microstructure of rennet-induced gels was drastically altered. Even when there were low levels of casein hydrolysis, the rheological properties of rennet gels were altered, which could have negative impacts on cheese yield and texture.

Animals↗
PubMed2001

A retro-inverso peptide mimic of CD28 encompassing the MYPPPY motif adopts a polyproline type II helix and inhibits encephalitogenic T cells in vitro.

Complete activation of T cells requires two signals: an Ag-specific signal delivered via the TCR by the peptide-MHC complex and a second costimulatory signal largely provided by B7:CD28/CTLA-4 interactions. Previous studies have shown that B7 blockade can either ameliorate experimental autoimmune encephalomyelitis by interfering with CD28 signaling or exacerbate the disease by concomitant blockade of CTLA-4 interaction. Therefore, we developed a functional CD28 mimic to selectively block B7:CD28 interactions. The design, synthesis, and structural and functional properties of the CD28 free peptide, the end group-blocked CD28 peptide, and its retro-inverso isomer are shown. The synthetic T cell-costimulatory receptor peptides fold into a polyproline type II helical structure commonly seen in regions of globular proteins involved in transient protein-protein interactions. The binding determinants of CD28 can be transferred onto a short peptide mimic of its ligand-binding region. The CD28 peptide mimics effectively block the expansion of encephalitogenic T cells in vitro suggesting the potential usefulness of the peptides for the treatment of autoimmune disease conditions requiring down-regulation of T cell responses.

Amino Acid Motifs↗
PubMed2001

Syntheses and structures of isomeric [6.6]- and [8.8]cyclophanes with 1,4-dioxabut-2-yne and 1,6-dioxahexa-2,4-diyne bridges.

All three isomers (ortho, meta, and para) of [8.8]cyclophane bearing 1,6-dioxahexa-2,4-diyne bridges have been synthesized and structually characterized by single-crystal X-ray crystallography to determine the conformation of the cyclophanes and their cavity dimensions. The three isomeric [6.6]cyclophanes bearing 1,4-dioxabut-2-yne bridges have also been synthesized from but-2-yne-1,4-diol ditosylate and the isomeric dihydroxybenzenes. The [6.6]orthocyclophane has been structurally characterized by single-crystal X-ray crystallography. The energy-minimized structures from the semiempirical AM1 calculations of these cyclophanes compare very well with the structures obtained by X-ray crystallography.

Journal Article↗
PubMed2001

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Education, Medical, Undergraduate↗
PubMed2001

Isolation and characterization of the promoter region of the rat kidney-type glutaminase gene.

A lambdaEMBL3 rat genomic library was screened to clone a phage that contained the promoter region of the kidney-type mitochondrial glutaminase gene. The resulting lambdaGA1 phage contained 13.7 kb of genomic DNA that was mapped by Southern blotting and restriction analysis. The 2.22 kb and 0.83 kb SacI fragments of lambdaGA1 were sequenced and the transcription initiation site was identified by RNase mapping. The reported sequence contains 2287 bp of the promoter, the entire exon 1 (542 bp), and 223 bp of the initial intron of the glutaminase gene. The initial exon contains 141 bp of 5'-nontranslated sequence and 401 bp of coding sequence that encodes the 72-amino acid mitochondrial targeting presequence and 61 amino acids from the N-terminus of the mature 66 kDa glutaminase subunit. Various segments of the GA promoter were cloned into a chloramphenicol acetyltransferase (CAT) expression vector. The resulting GA-CAT constructs were transfected into LLC-PK(1)-F(+) kidney cells to assess the promoter function of the isolated genomic DNA. The GA(-402)CAT construct produced a 10-fold greater CAT activity than the promoter-less pCAT vector. Analysis of various deletion constructs indicated that elements located between -402 and -63 bp must act in synergy with more proximal elements to create a functional promoter. The initial 402 bp segment lacks a TATA sequence but is GC-rich and contains two CCAAT boxes and two Sp1 sites.

Amino Acid Sequence↗
PubMed2001

Mmm1p, a mitochondrial outer membrane protein, is connected to mitochondrial DNA (mtDNA) nucleoids and required for mtDNA stability.

In the yeast Saccharomyces cerevisiae, mitochondria form a branched, tubular reticulum in the periphery of the cell. Mmm1p is required to maintain normal mitochondrial shape and in mmm1 mutants mitochondria form large, spherical organelles. To further explore Mmm1p function, we examined the localization of a Mmm1p-green fluorescent protein (GFP) fusion in living cells. We found that Mmm1p-GFP is located in small, punctate structures on the mitochondrial outer membrane, adjacent to a subset of matrix-localized mitochondrial DNA nucleoids. We also found that the temperature-sensitive mmm1-1 mutant was defective in transmission of mitochondrial DNA to daughter cells immediately after the shift to restrictive temperature. Normal mitochondrial nucleoid structure also collapsed at the nonpermissive temperature with similar kinetics. Moreover, we found that mitochondrial inner membrane structure is dramatically disorganized in mmm1 disruption strains. We propose that Mmm1p is part of a connection between the mitochondrial outer and inner membranes, anchoring mitochondrial DNA nucleoids in the matrix.

Actins↗