Biomedical subjects

K R Sridhar

Publications and source records attributed to K R Sridhar.

13 recordsLinked to original sources

PubMed2006

Transfer of [Flexibacter] sancti, [Flexibacter] filiformis, [Flexibacter] japonensis and [Cytophaga] arvensicola to the genus Chitinophaga and description of Chitinophaga skermanii sp. nov.

Analysis of the 16S rRNA gene sequences of species currently assigned to the genus Flexibacter has shown extensive intrageneric phylogenetic heterogeneity. It has been shown in previous studies that the species [Flexibacter] sancti, [Flexibacter] filiformis and [Flexibacter] japonensis were most closely related to Chitinophaga pinensis. In addition, [Cytophaga] arvensicola and species of the genus Terrimonas also clustered into this phylogenetic group. Although the similarities of 16S rRNA gene sequences were low (88.5-96.4 %), there is no evidence for clear phenotypic differences between these organisms that justify assignment to different genera. A proposal is made to transfer these species to the genus Chitinophaga as Chitinophaga sancti comb. nov., Chitinophaga filiformis comb. nov., Chitinophaga japonenis comb. nov. and Chitinophaga arvensicola comb. nov. on the basis of phylogenetic and phenotypic data. Furthermore, a novel species is described within this genus, Chitinophaga skermanii sp. nov., with strain CC-SG1B(T) (=CCUG 52510(T)=CIP 109140(T)) as the type strain.

Bacteroides↗

PubMed2005

210Po bioaccumulation in coastal sand dune wild legumes--Canavalia spp. of southwest coast of India.

In view of considerable natural background radioactivity reported from southwest coast of India, the current study documents bioaccumulation of 210Po in two dominant coastal sand dune perennial mat-forming wild legumes, Canavalia cathartica and C. maritima. Root, stem, leaf, mature beans, dry seeds and rhizosphere sand were analyzed for 210Po concentration. 210Po activity decreased in the order of leaves > roots > seeds > stems > beans. The highest 210Po activity was recorded in rhizosphere sand samples (5.78-5.88 Bq kg(-1)) followed by the leaf samples (3.27-3.07 Bq kg(-1)), while it was lowest in mature beans (0.13-0.20 Bq kg(-1)). 210Po activities or tissue moisture between plant species were not significantly different (p > 0.05; t-test). But 210Po activity vs. moisture differed significantly in all tissues (p = 0.0001), vegetative tissues (root, stem and leaf) (p = 0.0016), seeds (p = 0.0393) and proteins in seeds (p = 2.355 x 10(-6)) indicating the importance of moisture and protein in 210Po accumulation. Although 210Po has affinity for proteins, it did not concentrate too much in seed proteins of Canavalia. Concentration of 210Po in mature beans is at safe levels as fisher folk only consume tender pods occasionally. 210Po activity in Canavalia is compared with other plant materials. As the landraces of C. cathartica and C. maritima are distributed throughout pantropical coastal areas, the current study emphasizes on considering them as bioindicators to monitor 210Po in coastal sand dune biomes and in turn the health of coastal population.

Canavalia↗

PubMed2004

Nutrient composition and biological evaluation of an unconventional legume, Canavalia cathartica of mangroves.

Seeds of an unconventional legume, Canavalia cathartica from the mangroves of the southwest coast of India, were screened for proximate composition, minerals, protein fractions, amino acid profiles, fatty acids and some anti-nutritional factors. The seeds consisted of 31.2%, 1.86%, 61.4% and 1580 kJ crude proteins, crude lipid, crude carbohydrates and calories, respectively. The crude protein content of seeds was higher than common cereals, whole-wheat flour (8.55%), parboiled rice (7.7%) and egg (12.6%). Essential amino acids, threonine, cysteine + methionine, isoleucine, tyrosine + phenylalanine and lysine were higher than Food and Agricultural Organization of United Nations/World Health Organization patterns. On comparing the amino acid profile of mangrove and sand dune C. cathartica seeds, the latter were found to be superior (total amino acid content, 123.5% versus 60.8%), while the result was vice versa with respect to the polyunsaturated/saturated ratio (105.9 versus 2.52). The seeds possessed 1420 mg/100 g total phenolics and strong hemagglutination activity, while tannins and trypsin inhibition activity were absent. Physical, nutritional and anti-nutritional features of seeds of C. cathartica of the mangrove have been compared with those of C. cathartica of the sand dunes of the southwest coast of India. A significant difference (P < 0.05) was observed between the physical, proximal and mineral composition except for ash, magnesium and copper. The protein efficiency ratio, food efficiency ratio, net protein retention, protein retention efficiency, biological value, net protein utilization and true digestibility of C. cathartica seeds were significantly different (P < 0.05) from casein. In spite of the high protein content, animal-feeding trials indicated low nutritional quality. Nutritional, anti-nutritional factors and protein qualities of seeds C. cathartica have been discussed in comparison with other species of Canavalia.

Amino Acids↗

PubMed2004

Endophytic fungal diversity of 2 sand dune wild legumes from the southwest coast of India.

Endophytic fungi of 3 age classes (seeds, seedlings, and mature plants) and 5 tissue classes (cotyledons, seed coats, roots, stems, and leaves) of coastal sand dune legumes Canavalia cathartica and Canavalia maritima were assessed by plating surface-sterilized segments on malt extract agar. Forty-six fungal taxa comprising 6 ascomycetes, 33 mitosporic fungi, 2 zygomycetes, and 5 sterile morphospecies were recovered. There was no significant difference in the colonization frequency of endophytes between plant species (p = 0.4098, Student's t test). Among the age classes, endophytic fungi colonized over 90% of seedlings and mature plants. Similarly, among tissue classes, endophytic fungi colonized over 90% of root, stem, and leaf segments. Diversity and richness of endophytic fungi were higher in C. cathartica than in C. maritima. Rarefaction curves revealed a "higher expected number of species" in mature plants of C. cathartica and seedlings of C. maritima, whereas it was highest in leaves of both plant species. The most dominant endophyte, Chaetomium globosum, colonized over 50% of the root, stem, and leaf segments of C. maritima and over 50% of the root segments of C. cathartica. The colonization frequency of C. globosum was found to be 5%-12.5% in seeds and increased up to 40%-64.4% in seedlings or mature plants. Halosarpheia sp. was the only marine fungus recovered among the endophytes.

Canavalia↗

PubMed2003

Aquatic hyphomycetes in polluted groundwater habitats of central Germany.

Polluted groundwater wells located in a former copper shale mining district (11 sites; Mansfelder Land, Central Germany) and in meadows of the Mulde and Elbe rivers (2 sites) were assessed for occurrence and species richness of aquatic hyphomycetes. Water temperatures at all sites were relatively low and fluctuated less than in surface waters. Oxygen concentrations were always below saturation, whereas sulfate, nitrate, and phosphate levels reached extremely high values in several of the wells. Relatively high levels of Pb, Mn, and Fe were found in some of the wells, but overall few concentrations of individual metals and metalloids exceeded European guidelines for drinking water. Pollen tube growth inhibition, used to assess cytotoxicity of the water, ranged between 4 and 50%. Between 1 and 10 distinct species of aquatic hyphomycetes colonized sterile Alnus glutinosa leaves exposed at the Mansfelder Land sites; for the meadow sites, 8-20 species were found. Heliscus lugdunensis and Anguillospora sp. were the two most widespread species. Fungal colonization occurred much more slowly than in surface water, as demonstrated by scanning electron microscopy and the release of conidia from recovered leaves. The conidial output from exposed alder leaves ranged from 0.2 to 95 conidia mg (-1) dry mass, corresponding to 10% of the values for contaminated surface waters in the same region. Overall, groundwater appears to be a marginal habitat for aquatic hyphomycetes, but may nevertheless play a vital role as long-term reservoir facilitating rapid recolonization following a collapse in fungal communities in surface waters.

Copper↗

PubMed2002

Diversity of endophytic fungi in the roots of mangrove species on the west coast of India.

Because mangrove plant species are a valuable source of useful metabolites, their endophytes have gained more importance. Randomly sampled surface-sterilized whole root segments of four mangrove plant species, Acanthus ilicifolius, Avicennia officinalis, Rhizophora mucronata, and Sonneratia caseolaris from the mangroves of Udyavara (Karnataka) on the west coast of India, were characterized for fungal communities by direct plating, damp chamber, and bubbling chamber incubation methods. The richness of endophytic fungal species from whole root segments after direct plating and damp chamber incubation was greatest for R. mucronata than for other plants (18 vs. 8-13). Incubation of whole root segments in bubbling chambers yielded conidia of two freshwater hyphomycetes: Mycocentrospora acerina (in Avicennia officinalis) and Triscelophorus acuminatus (in R. mucronata and in S. caseolaris). Surface-sterilized whole root and root bark segments of R. mucronata sampled from the mid-tide level on direct plating yielded more fungi than that of the root segments sampled from low-tide and high-tide levels. The greatest number of isolates, species richness, and diversity of fungi were shown by the whole root segments of R. mucronata from the mid-tide level. Rarefaction indices also revealed the highest expected number of species out of 150 random isolations from the mid-tide level samples of whole root and root bark segments of R. mucronata. The present study showed that fungi in mangrove roots are composed of a consortium of soil, marine, and freshwater fungi.

Acanthaceae↗

PubMed2001

Aniptodera indica, a new species of mangrove inhabiting ascomycete from west coast of India.

On decomposing mangrove leaves and woods collected from west coast of India, a new species of Aniptodera was encountered. Aniptodera indica sp. nov. differs from other members of the genus, as the ascospores possess single polar appendage. This new species is described, illustrated and compared with closely resembling species: Aniptodera chesapeakensis and A. juncicola.

Animals↗

PubMed2000

In-situ resource utilization technologies for Mars life support systems.

The atmosphere of Mars has many of the ingredients that can be used to support human exploration missions. It can be "mined" and processed to produce oxygen, buffer gas, and water, resulting in significant savings on mission costs. The use of local materials, called ISRU (for in-situ resource utilization), is clearly an essential strategy for a long-term human presence on Mars from the standpoints of self-sufficiency, safety, and cost. Currently a substantial effort is underway by NASA to develop technologies and designs of chemical plants to make propellants from the Martian atmosphere. Consumables for life support, such as oxygen and water, will probably benefit greatly from this ISRU technology development for propellant production. However, the buffer gas needed to dilute oxygen for breathing is not a product of a propellant production plant. The buffer gas needs on each human Mars mission will probably be in the order of metric tons, primarily due to losses during airlock activity. Buffer gas can be separated, compressed, and purified from the Mars atmosphere. This paper discusses the buffer gas needs for a human mission to Mars and consider architectures for the generation of buffer gas including an option that integrates it to the propellant production plant.

Argon↗

PubMed2000

Initial colonization, nutrient supply, and fungal activity on leaves decaying in streams.

Aquatic hyphomycetes dominate leaf decomposition in streams, and their biomass is an important component in the diet of leaf-eating invertebrates. After 2 weeks of exposure in a first-order stream, maple leaf disks had low levels of fungal biomass and species diversity. Spore production by aquatic hyphomycetes also was low. Subsets of these disks were left in the stream for another 3 weeks or incubated in defined mineral solutions with one of three levels of nitrate and phosphate. Stream disks lost mass, increased ergosterol levels and spore production, and were colonized by additional fungal species. External N and P significantly stimulated mass loss, ergosterol accumulation, and spore production of laboratory disks. On disks incubated without added N and P, ergosterol levels declined while conidium production continued, suggesting conversion of existing hyphal biomass to propagules. In all other treatments, approximately equal amounts of newly synthesized biomass were invested in hyphae and conidia. Net yield (fungal biomass per leaf mass lost) varied between 1% (in the laboratory, without added N or P) and 31% (decay in stream). In most treatments, the three aquatic hyphomycete species that dominated spore production during the first 2 weeks in the stream also produced the largest numbers of conidia in the following 3 weeks. Principal-component analysis suggested two divergent trends from the initial fungal community established after 2 weeks in the stream. One culminated in the community of the second phase of stream exposure, and the other culminated in the laboratory treatment with the highest levels of N and P. The results suggest that fungal production in streams, and, by extension, production of invertebrates and higher tropic levels, is stimulated by inorganic N and P.

Ecosystem↗

PubMed1999

Delta-9-tetrahydrocannabinol delays the gastric emptying of solid food in humans: a double-blind, randomized study.

BACKGROUND: Delta-9-tetrahydrocannabinol (THC), the active constituent of marijuana, is an effective agent in the prevention of chemotherapy-induced nausea and vomiting. AIM: To determine the effect of THC on gastric emptying of a radiolabelled solid food in humans. METHODS: Thirteen healthy volunteers underwent gastric emptying studies after receiving THC and placebo in a randomized double-blind fashion on 2 separate days. THC, at a dose of 10 mg/m2 of body surface area, or placebo were administered. RESULTS: Gastric emptying after THC was slower than placebo in all subjects. Mean percentage of isotope remaining in the stomach was significantly greater than after placebo from 30 min (85.5 +/- 4.3% vs. 94.2 +/- 1. 4% placebo and THC, respectively, P < 0.05) to 120 min (45.6 +/- 7. 2% vs. 73.9 +/- 7.1% placebo and THC, respectively, P < 0.001) after the test meal. No correlation was found between plasma THC levels and the delay in gastric emptying. CONCLUSIONS: THC at a dose used for preventing chemotherapy-induced nausea and vomiting significantly delays gastric emptying of solid food in humans. Therefore, the anti-emetic property of THC may be mediated through the central nervous system.

Adult↗

PubMed1999

Quantitative phase contrast images to quantitate flow in a rat model of microgravity.

A magnetic resonance angiographic (MRA) technique for noninvasive measurement of flow in the inferior vena cava (IVC) was used to study blood flow changes in a simulated microgravity model. Microgravity was simulated in adult male Fischer 344 rats (n = 12, with each rat acting as its own control) using a tail harness to elevate the hindquarters, producing a non-weight bearing hindlimb (NWH) model. Quantitative phase contrast images of flow within the IVC were obtained initially and after a 2-week NWH protocol. Inferior vena cava blood flow was determined by converting the intensity at the respective magnetic resonance pixels into a corresponding flow by Doppler techniques. Average values for flow determined with MR angiography were 351.8 (SEM = 49) mm3 x s(-1) initially and 524.5 (SEM = 46) mm3 x s(-1) after exposure to 2 weeks of the NWH protocol. Post 2-week NWH flow increased 49.1% over the initial NWH value. Using a paired t-test, a significant difference was found between the rats' IVC flow values in the initial and post-NWH groups (p < 0.004). The changes in IVC blood flow due to 45 degrees NWH may contribute to the overall changes observed in the cardiovascular system during simulated microgravity.

Animals↗

PubMed1998

Prevalence of impaired gastric emptying of solids in systemic sclerosis: diagnostic and therapeutic implications.

The aims of this study were to evaluate the gastric emptying of solids in patients with progressive systemic sclerosis, correlate the esophageal motility abnormalities with their gastric emptying status, delineate the symptoms suggestive of abnormal gastric emptying, and assess the effect of metoclopramide in patients with abnormally slow gastric emptying. Twenty patients underwent esophageal motility evaluation and gastric emptying studies with a radiolabeled solid meal. Gastric emptying was also measured in 13 healthy volunteers. Four patients in whom esophageal motility was normal also had an accompanying normal rate of gastric emptying. In 16 patients with abnormal esophageal motility, mean gastric emptying was significantly delayed as compared with that in normal subjects (67.4% vs 49.8% retention of isotope at 2 hours, P < .05). Ten patients had absolute criteria for slow gastric emptying (>+2 SD). However, only postprandial bloating and early satiety were symptoms that accurately predicted slow radionuclide emptying. In four of these patients in whom gastric emptying was slow, 10 mg intramuscular metoclopramide significantly (P < .05 vs baseline) accelerated the gastric emptying of the same test meal. We conclude that (1) gastric emptying of solids was delayed in approximately two thirds of patients with abnormal esophageal motility, whereas it was normal in patients with normal esophageal motor function; (2) metoclopramide significantly accelerated this slow gastric emptying; and (3) delayed gastric emptying contributes to the severity of the gastroesophageal reflux frequently present in patients with progressive systemic sclerosis, and promotility agents offer a valuable therapeutic approach.

Adult↗

PubMed1990

Observations on bacteria associated with pigeon crop.

Lactobacilli, streptococci and coliforms of pigeon crop contents, 5th wash, macerate and those of first-day pigeon milk have been studied. Streptococci predominated in all the samples tested. Relatively higher counts of lactobacilli and streptococci in crop macerate than in the 5th wash suggested the adhesion of these bacteria to crop wall. Because of frequent occurrence in crop of partially digested fibrous food, its contents were tested for the presence of cellulolytic bacteria. The results indicated that four isolates were capable of utilizing cellulose with the resultant production of reducing sugars. It is inferred that the crop microflora is involved in the degradation of dietary fibre in the pigeon.

Animals↗