Biomedical subjects

D N Singh

Publications and source records attributed to D N Singh.

At least 19 recordsLinked to original sources

PubMed2006

Antifungal anthraquinones from Saprosma fragrans.

A new 3,4-dihydroxy-1-methoxy anthraquinone-2-corboxaldehyde (1) together with a known anthraquinone, damnacanthal (2), were isolated from the chloroform fraction of the aerial part (whole plant without root) of Saprosma fragrans. The isolated anthraquinones (1) and (2) were found to exhibit antifungal activity against Trichophyton mentagrophytes and Sporitrichum schenckii. Their structures were established by chemical and spectral analysis.

Anthraquinones↗

PubMed2006

Prediction of ingredient quality and the effect of a combination of xylanase, amylase, protease and phytase in the diets of broiler chicks. 1. Growth performance and digestible nutrient intake.

1. A total of 2208 broiler chicks were used in two growth experiments (8 treatments and 12 replicate pens in each experiment) to assess the effects of xylanase, amylase, protease and phytase in maize-based diets. 2. A positive control diet was formulated containing adequate nutrient concentrations. A negative control diet was formulated to contain approximately 628 kJ/kg, 0.13%, 0.12% and 1 to 2% less metabolisable energy (ME), phosphorus (P), calcium (Ca) and amino acids, respectively, than the positive control. In addition, two further negative control diets that contained 167 or 334 kJ/kg more ME, respectively, than negative control 1 were formulated. 3. A further 4 dietary treatments were made by supplementing each of the 4 negative control diets with a combination of xylanase, amylase, protease and phytase, resulting in 8 dietary treatments in a 4 by 2 factorial arrangement. 4. The scale of the removal of energy, P, Ca and amino acids from the positive control diet was determined using least square models based on in vivo data for both the xylanase/amylase/protease cocktail and for phytase and it was predicted that performance of birds fed on negative control 1 would be returned by supplemental enzymes to that of those fed on the positive control. 5. In both experiments there was a significantly poorer performance in birds fed on the negative control 1 than in those fed on the positive control. The poorer weight gain and feed conversion ratio could be attributed in part to a reduced intake of digestible energy, P, nitrogen (N) and amino acids associated with birds fed on the negative control diet. 6. Supplementation of the negative control diets with the enzyme combination returned performance to that of the positive control in both experiments. 7. These data indicate that exogenous xylanase, amylase, protease and phytase can be used successfully in a strategically formulated low nutrient density diet to maintain performance to that of birds fed on a nutritionally adequate diet.

6-Phytase↗

PubMed2006

Prediction of ingredient quality and the effect of a combination of xylanase, amylase, protease and phytase in the diets of broiler chicks. 2. Energy and nutrient utilisation.

1. In order to investigate the effects of xylanase, amylase, protease and phytase in the diets of broiler chickens containing graded concentrations of metabolisable energy (ME), two 42-d experiments were conducted using a total of 2208 broiler chicks (8 treatments with 12 replicate pens in each experiment). 2. Four diets including one positive and three negative control diets were used. Three maize/soybean meal-based negative control (NC) diets were formulated to be identical in available phosphorus (P), calcium (Ca) and amino acids but NC1 contained approximately 0.17 MJ/kg less ME than NC2 and approximately 0.34 MJ/kg less ME than NC3. A positive control (PC) was fed for comparison and was formulated to be adequate in all nutrients, providing approximately 0.63 MJ/kg ME, 0.13% available P, 0.12% Ca and 1 to 2% amino acids more than NC1. 3. The reduction in nutrient density between NC1 and PC was determined using ingredient quality models Avichecktrade mark Corn and Phychecktrade mark that can predict the response to exogenous enzymes in maize/soybean meal-based broiler diets. Supplementation of each diet with or without a cocktail of xylanase, amylase, protease and phytase gave a total of 8 dietary treatments in a 4 x 2 factorial arrangement. The same treatments and diet designs were used in both experiments but conducted in different locations using different batches of maize, soybean meal and minor ingredients. 4. In both experiments, digestibility was improved by the addition of exogenous enzymes, particularly those for P, Ca and certain amino acids. In addition, the supplementation of the PC with enzymes elicited a positive response indicating that over-the-top addition of xylanase, amylase, protease and phytase may offer a nutritionally and economically viable alternative to feed cost reduction. 5. It can be concluded that the digestibility of nutrients by broilers fed on maize/soybean meal-based diets can be improved by the use of a combination of xylanase, amylase, protease and phytase.

6-Phytase↗

PubMed2005

A novel technique for monitoring contaminant transport through soils.

An experimental setup which is capable of simulation as well as monitoring contaminant transport through soil mass has been developed. Efficiency of the experimental setup has been demonstrated by comparing the results obtained from the argentometric method. Reynolds number (R(e)) and the Peclet number (P(e)) have been found to be less than unity. This indicates that flow of the solute through soil mass is laminar and the dominant contaminant transport mechanism is diffusion.

Calibration↗

PubMed2004

Experimental methodology to assess contaminant diffusion in rock mass.

Monitoring changes in electrical conductivity (EC) of aqueous phase, due to contaminant diffusion through porous media, is one of the techniques followed by researchers to understand the migration mechanism. However, the contaminant diffusion in the rock mass is a slow process and hence detecting small changes in conductivity with the help of conventional laboratory conductivity meters is quite difficult. With this in view, an experimental methodology to monitor diffusion of contaminant(s) through the intact and fractured rock mass, with the help of a USDTS (Ultra-Sensitive Devices and Technical Services) conductivity meter, has been developed. Results have been validated with those obtained from the ion chromatograph (IC) technique and a good agreement has been noted. The study demonstrates usefulness of the proposed methodology for online monitoring of contaminant migration through the porous media.

Diffusion↗

PubMed2001

Laser Raman and IR spectra and force fields for 2,4-dichlorobenzonitrile.

Raman spectrum of 2,4-dichlorobenzonitrile (2,4-DCBN) in powder form has been recorded in the region 50-4000 cm(-1) on a Jasco K-500 Raman spectrophotometer using the 488.0 nm radiation from an argon laser. FTIR spectra in the region 200-4000 cm(-1) have been recorded in KBr pellet and nujol mull on a Nicolet DX spectrometer. Using the observed Raman and IR frequencies, normal co-ordinate analysis has been carried out to support the vibrational analysis and to determine the planar and non-planar force fields.

Chlorine Compounds↗

PubMed2001

Functional analysis of polar amino-acid residues in membrane associated regions of the NHE1 isoform of the mammalian Na+/H+ exchanger.

The NHE1 isoform of the Na+/H+ exchanger is a ubiquitous plasma membrane protein that regulates intracellular pH in mammalian cells. Site-specific mutagenesis was used to examine the functional role of conserved, polar amino-acid residues occurring in segments of the protein associated with the membrane. Seventeen mutant proteins were assessed by characterization of intracellular pH changes in stably transfected cells that lacked an endogenous Na+/H+ exchanger. All of the mutant proteins were targeted correctly to the plasma membrane and were expressed at similar levels. Amino-acid residues Glu262 and Asp267 were critical to Na+/H+ exchanger activity while mutation of Glu391 resulted in only a partial reduction in activity. The Glu262-->Gln mutant was expressed partially as a deglycosylated protein with increased sensitivity to trypsin treatment in presence of Na+. Substitution of mutated Glu262, Asp267 and Glu391 with alternative acidic residues restored Na+/H+ exchanger activity. The Glu262-->Asp mutant had a decreased affinity for Li+, but its activity for Na+ and H+ ions was unaffected. The results support the hypothesis that side-chain oxygen atoms in a few, critically placed amino acids are important in Na+/H+ exchanger activity and the acidic amino-acid residues at positions 262, 267 and 391 are good candidates for being involved in Na+ coordination by the protein.

Amino Acid Sequence↗

PubMed1996

Post-operative radiotherapy in carcinoma of buccal mucosa, a prospective randomized trial.

Squamous cell carcinoma of the buccal mucosa is a common cancer in India. We are referred a large number of locally advanced lesions where curative surgery is still possible. The objective of this study is to determine the role of post-operative radiotherapy in enhancing disease-free survival. Patients with stages III and IV cancer of the buccal mucosa potentially curable by surgery were randomized to surgery only or post-operative radiotherapy. Patients were followed up for 3 years. The clinico-pathological features in both arms were comparable. Disease-free survival at the end of the study was found to be 38% and 68% (P<0.005) respectively. Post-operative radiotherapy was thus seen to improve disease-free survival in squamous cell carcinoma of the buccal mucosa.

Carcinoma, Squamous Cell↗

PubMed1993

Clinical and cytogenetic survey of institutionalized mentally retarded patients with emphasis on the fragile-X syndrome.

A detailed clinical and cytogenetic survey for the fragile-X syndrome was undertaken on 201 institutionalized mentally retarded males with no previously recognized cause of retardation, and the causes of mental retardation were summarized from a total of 595 institutionalized male and female patients after the review of their medical records including clinical and cytogenetic data. Among the 201 males clinically and cytogenetically examined, five (2.5%) had abnormal chromosome findings with four (2%) having the fragile-X syndrome. Twelve of the males (6.0%) were diagnosed with a single gene disorder. In the present study, mental retardation was classified as possibly due to multifactorial causes when a genetic syndrome, chromosome abnormality or environmental insult was not identified, but mental retardation was present in one or more first and/or second degree relatives, but did not follow a recognizable inheritance pattern. Hence, mental retardation was recorded in other family members and may indicate possible multifactorial causes in 45 males (22.4%). An environmental insult was noted in 25 males (12.4%); unexplained birth defects in three males (1.5%); a specific condition or diagnosis identified, but cause unknown (e.g. Rubinstein-Taybi syndrome) in 10 males (5%); and no diagnosis made in the remaining 101 males (50.2%). Of all 595 patients (334 males and 261 females), including the 201 males who had undergone a detailed clinical and cytogenetic evaluation, 39 (6.6%) had abnormal chromosome findings, with Down's syndrome noted in 31 of the patients. Twenty-five patients (4.2%) were diagnosed with a single gene disorder while mental retardation was noted in other family members and may indicate possible multifactorial causes in 64 patients (10.8%). An environmental insult was noted in 170 patients (28.6%); unexplained birth defects in 17 patients (2.9%); a specific condition or diagnosis but cause unknown in 27 patients (4.5%); and no diagnosis made in 253 patients (42.5%). Clinical and cytogenetic screening of mentally retarded patients for the fragile-X syndrome and other causes of mental retardation is helpful in identifying individuals and their families who may benefit from genetic services such as counseling and treatment. This study was performed over an approximate 2 year period from 1987 to 1989.

Adolescent↗

PubMed1993

Anthropometric and craniofacial patterns in mentally retarded males with emphasis on the fragile X syndrome.

Anthropometric and craniofacial profile patterns indicating the percent difference from the overall mean were developed on 34 physical parameters with 31 white, mentally retarded males (23 adults and 8 children) with the fra(X) syndrome matched for age with 31 white, mentally retarded males without a known cause of their retardation. The fra(X) syndrome males consistently showed larger dimensions for all anthropometric variables, with significant differences for height, sitting height, arm span, hand length, middle finger length, hand breadth, foot length, foot breadth, and testicular volume. A craniofacial pattern did emerge between the two groups of mentally retarded males, but with overlap of several variables. Significant differences were noted for head circumference, head breadth, lower face height, bizygomatic diameter, inner canthal distance, ear length and ear width, with the fra(X) syndrome males having larger head dimensions (head circumference, head breadth, head length, face height and lower face height), but smaller measurements for minimal frontal diameter, bizygomatic diameter, bigonial diameter, and inner canthal distance. Several significant correlations were found with the variables for both mentally retarded males with and without the fra(X) syndrome. In a combined anthropometric and craniofacial profile of 19 variables comparing 26 white fra(X) syndrome males (13 with high expression (> 30%) and 13 with low expression (< 30%), but matched for age), a relatively flat profile was observed with no significant differences for any of the variables. Generally, fra(X) syndrome males with increased fragile X chromosome expression have larger amplifications of the CGG trinucleotide repeat of the FMR-1 gene. No physical differences were detectable in our study between fra(X) males with high expression and apparently larger amplifications of the CGG trinucleotide repeats compared with those patients with low expression. Our research illustrates the use of anthropometry in identifying differences between mentally retarded males with or without the fra(X) syndrome and offers a comprehensive approach for screening males for the fra(X) syndrome and selecting those individuals for cytogenetic and/or molecular genetic testing.

Adolescent↗

PubMed1991

A 15-item checklist for screening mentally retarded males for the fragile X syndrome.

A 15-item checklist, including physical and behavioral features frequently observed in fragile X syndrome, was used in a prospective study of 188 mentally retarded males in order to identify males at risk for this syndrome. Of the 188 males, 19 were found to have the fragile X syndrome, while the remaining 169 males had no recognizable cause of their mental retardation, including normal chromosomes. Significant differences (p less than 0.01) were found between mentally retarded males with and without the fragile X syndrome with increased hyperactivity; shorter attention span; more tactile defensiveness, hand-flapping, perseverative speech, and hyperextensibility; large ears and testes; higher frequency of simian creases or Sydney lines and plantar creases; and more positive family histories of mental retardation in the fragile X syndrome males. Multiple regression and discriminant analyses of the 188 males indicated several physical features were useful predictors for inclusion in the fragile X syndrome group. An overall correct classification rate of 93% was achieved based on 6 variables (plantar crease, simian crease, hyperflexibility, large testes, large ears, and a positive family history of mental retardation) that were entered into the discriminant equation. Therefore, our experience with a 15-item checklist suggests the potential of screening for the fragile X syndrome in mentally retarded males and that 6 of the 15 variables were particularly good predictors of this syndrome.

Adolescent↗

PubMed1989

Chromosomal mapping and nucleotide sequence of a human DNA autonomously replicating sequence.

A 1.1-kb human DNA fragment (ARSH1) capable of functioning as a putative origin of replication in yeast cells has been characterized both by in situ hybridization to human metaphase chromosomes and by DNA sequencing. Our hybridization studies show a preferential localization of ARSH1 in chromosome regions 1p34-36 and 2q34-37. DNA sequence analysis indicates that in addition to the consensus sequence required for ARS function in yeast cells, nuclear matrix-associated DNA motifs are also present in the 1.1-kb fragment. These results suggest that ARSH1 sequences may serve as points of anchorage to the nuclear matrix for chromosomes 1 and 2.

Amino Acid Sequence↗

PubMed1989

Immunocytochemical studies of astrocytes following injury to the cerebral cortex of the rat.

The morphological change of cerebral cortex astrocytes from protoplasmic to glial fibrillary acidic protein (GFAP)-containing cells is induced by injury. Protoplasmic astrocytes that contain no detectable amount of GFAP become filled with GFAP and their processes extend to form the glial scar around the wound. It is hypothesized that this transformation is induced by cAMP and neurotransmitters released from damaged neuronal cells. A similar mechanism may be present in other brain regions following injury or disease.

Animals↗

PubMed1989

Morphology and distribution of tanycytes in the third ventricle of the adult rat. A study using semithin methacrylate sections.

Light microscopy and semithin methacrylate sections were used to study the tanycytic projections and morphology in the floor of the third ventricle of the rat. The tanycytic cell soma was located in the ependyma. The luminal surface showed minute protrusions into the ventricular space and their basal processes projected across the width of the parenchyma of the infundibular region. During their course, tanycytic processes made contact with capillaries in the parenchyma and pial surface, suggesting that they might be involved in uptake and/or delivery mechanisms between the cerebrospinal fluid, hypothalamic cells and blood vessels.

Animals↗

PubMed1987

Urinary mucoprotein in pediatric urolithiasis.

Primary bladder stone is a common pediatric surgical problem in developing countries. Many theories are prevalent. The stone matrix theory is based on increased excretion of its precursor, the uromucoid (the urinary mucoprotein). Uromucoid, studied in urine and stones by the electroimmunodiffusion technique in 49 cases with controls, showed significantly increased excretion in stone cases. Family income and serum protein were the only important influencing factors (negative). Causal relationship between uromucoid excretion, stone matrix, and pediatric bladder stones is discussed. Methylene blue decreased uromucoid excretion but not magnesium oxide, vitamin C or B6 (four common therapeutic drugs for prevention/dissolution of urolithiasis).

Ascorbic Acid↗

PubMed1987

Adrenomedullary chromaffin cells of the rat. An ultrastructural study.

Adrenomedullary chromaffin cells of the rat were studied at the ultrastructural level. Chromaffin cells contained a large population of electron-dense-core vesicles of two types, one very electron-dense (norepinephrine) and the other moderately electron-dense (epinephrine). The vesicles showed an even distribution pattern in the cytoplasmic matrix. No physical contacts were observed between cytoplasmic and vesicle membranes to indicate exocytosis, a mechanism frequently observed in the hamster. For chromaffin cells to be used as a transplantable source of dopamine, both the cells and vesicles must survive the trauma of denervation and vascular elimination or alternatively acquire the two factors from the transplantation site.

Adrenal Medulla↗

PubMed1986

Survival of adrenal gland implants in the neocortex of the rat: a morphological study.

The survival of adrenal gland implantation in the cerebral cortex of the rat was studied. In the present study, mature adrenal gland had survived after six months of implantation. No scar tissue was observed between the adrenal gland cortex and the host cerebral cortex. The implanted tissue showed some reorganization in its cortex and medulla. In the adrenal cortex there was an observable increase in connective tissue fibers and some degeneration of cells. In the medulla, again, both surviving and degenerating cells were observed. This study shows that mature adrenal gland has the capacity to survive after implantation in the cerebral cortex of the rats. Further studies are being carried out on fetal and mature tissue implantation and the ability of the adrenal medulla to secrete catecholamines.

Adrenal Glands↗

PubMed1984

Ultrastructural study of lysosomes in the myocardium of spontaneously hypertensive rats under chronic salt ingestion.

The presence of lysosomes and lysosomal-like bodies in the myocardium of spontaneously hypertensive rats (SHRs) under the influence of 1% NaCl was studied. In SHRs, 2 weeks and older, there was an observable increase of lysosomes and lysosomal-like bodies in the myocardium when compared to the myocardium of age-matched controls. It is postulated that degradation is initiated by primary lysosomes and that mitochondria seem to be a prime target. The degradation process is also believed to be a relevant factor in cardiac hypertrophy of SHRs and that a high NaCl intake coupled with a sustained high blood pressure enhanced this process.

Animals↗