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Biomedical subjects

G Ravindran

Publications and source records attributed to G Ravindran.

10 recordsLinked to original sources
PubMed2005

Screening for unilateral intracranial abnormalities using near infrared spectroscopy: a preliminary report.

Near infrared spectroscopy (NIRS) is being increasingly used for medical applications, including neurosurgical care. This preliminary report describes the use of a low cost, indigenous, non-invasive system where NIRS is used to identify superficial unilateral intracranial abnormalities. The optical density (OD) over each hemisphere was initially studied in 50 normal volunteers. The specificity, sensitivity, reliability and reproducibility of the NIRS generated from the developed equipment in detecting OD were thus confirmed. The OD over each hemisphere was then measured in 71 other individuals, immediately after a computed tomography (CT) scan of the brain was performed. Data was statistically analysed to find the average OD difference (compared to the opposite side) of the various intracranial compartments. Differences in OD suggested a unilateral intracranial abnormality. All those in whom OD differences were detected with the NIRS system had unilateral abnormalities on the CT scan. None of the 53 patients who had a normal CT scan had significant differences in OD.

Adolescent↗
PubMed2005

Diabetic Retinopathy Analysis.

Diabetic retinopathy is one of the common complications of diabetes. Unfortunately, in many cases the patient is not aware of any symptoms until it is too late for effective treatment. Through analysis of evoked potential response of the retina, the optical nerve, and the optical brain center, a way will be paved for early diagnosis of diabetic retinopathy and prognosis during the treatment process. In this paper, we present an artificial-neural-network-based method to classify diabetic retinopathy subjects according to changes in visual evoked potential spectral components and an anatomically realistic computer model of the human eye under normal and retinopathy conditions in a virtual environment using 3D Max Studio and Windows Movie Maker.

Journal Article↗
PubMed2004

Endogenous amino acid flow in the avian ileum: quantification using three techniques.

The aim of the present study was to compare the protein-free diet, guanidinated casein (GuC) and enzyme hydrolysed casein (EHC) methods for the quantification of endogenous amino acid (AA) flow in the avian ileum. Growing broiler chickens (5 weeks old) were used. All three assay diets were based on dextrose, and in the GuC and EHC diets GuC or EHC were the sole source of N. Endogenous AA flows determined with the use of protein-free diet were considerably lower (P<0.05) than those determined by the GuC and EHC methods. The total endogenous AA flows determined by the GuC and EHC methods were almost 3-fold greater (P<0.05) than those determined by the protein-free diet. The endogenous AA values obtained from GuC and EHC methods were similar (P>0.05), except for the flow of arginine, which was lower (P<0.05) in the EHC method. Glutamic acid, aspartic acid, threonine and glycine were the predominant endogenous AA present in digesta from the distal ileum. The contents of methionine, histidine and cystine were lower compared with other AA. The method of determination had no effect on the AA composition of endogenous protein, except for threonine, glutamic acid, lysine, arginine and cystine. The concentrations of threonine and arginine were lower (P<0.05) and that of lysine was higher (P<0.05) with the EHC method compared with the other two methods. The concentration of glutamic acid was greater (P<0.05) and that of cystine was lower (P<0.05) in the EHC and GuC methods compared with the protein-free diet method. The results showed that the ileal endogenous flows of N and AA are markedly enhanced by the presence of protein and peptides, above those determined following feeding of a protein-free diet. It is concluded that the use of EHC and GuC methods enables the measurement of ileal endogenous losses in chickens under normal physiological conditions.

Amino Acids↗
PubMed2002

Trypsin activity in stool and duodenal aspirate of neonates for differential diagnosis of intestinal obstruction.

The diagnosis of a non-surgical cause of delayed passage of meconium in a neonate may be challenging to the pediatric surgeon. The usefulness of determining trypsin activity (TA) in stool and duodenal aspirate for the diagnosis of cystic fibrosis (CF) and the existence of an entity called transient deficiency of trypsin (TTD) was assessed in 49 neonates over a 14-month period. TA was determined by a gelatin liquefaction technique. An absence of TA was considered if gelatin liquefaction was seen at a dilution of less than 1:100. Neonates with negative activity in both samples were started on supplementary pancreatic enzymes (pancreatin) for 1 month. TA was retested in the stool after stopping pancreatin for 1 week. Neonates with a return of TA were considered to have TTD; those who showed persistent TA deficiency at re-evaluation were investigated for CF by sweat iontophoresis. Twenty-one neonates had negative TA (in 1 only stool was tested); 13 could be re-evaluated (4 died, 4 were lost to follow-up). Nine were found to have TTD as a stool or duodenal sample showed the presence of TA; 3 of 4 patients with persistent negative TA were confirmed to have CF. One patient with normal sweat chloride is awaiting genetic studies. Determination of TA by gelatin liquefaction is a simple, rapid, inexpensive, and reliable (sensitivity 100%, negative predictive value 100%) means to differentiate non-surgical causes of intestinal obstruction such as neonatal and postoperative TTD and CF.

Clinical Enzyme Tests↗
PubMed2001

Microbial phytase improves performance, apparent metabolizable energy, and ileal amino acid digestibility of broilers fed a lysine-deficient diet.

An experiment was conducted to examine the effects of adding microbial phytase (Natuphos) on the performance in broilers fed a phosphorus-adequate, lysine-deficient diet. A wheat-soybean meal-sorghum-based diet, containing 1.00% lysine and 0.45% nonphytate phosphorus, was supplemented with L-lysine monochloride to provide 1.06, 1.12, or 1.18% lysine or with 125, 250, 375, 500, 750, or 1,000 phytase units (FTU)/kg diet. Each diet was fed to six pens of 10 chicks each from Day 7 to 28 posthatching. Addition of lysine to the lysine-deficient diet linearly increased (P < 0.001) weight gain and gain per feed of broilers. The response in weight gain to added phytase reached a plateau at 500 FTU/kg diet (quadratic effect, P < 0.001). Phytase had no effect on gain per feed to 250 FTU/kg diet and then increased (quadratic effect, P < 0.05) with further additions. Assuming that the observed responses in weight gain and gain per feed to added phytase were due to the release of lysine alone and by solving linear or nonlinear response equations of lysine and phytase levels, the lysine equivalency value was calculated to be 500 FTU phytase/kg diet = 0.074% lysine. Addition of increasing levels of supplemental phytase to the lysine-deficient diet improved (P < 0.001) the digestibilities of nitrogen and all amino acids. Phytase also increased the AME, and the response reached a plateau at 750 FTU/kg diet (quadratic effect, P < 0.001). These results showed that amino acid and energy responses are responsible for the performance improvements observed when phytase was added to a wheat-soybean meal-sorghum-based diet.

6-Phytase↗
PubMed1999

A comparison of ileal digesta and excreta analysis for the determination of amino acid digestibility in food ingredients for poultry.

1. The apparent ileal and excreta digestibilities of amino acids in 15 samples representing 12 food ingredients were determined using 5-week-old male broiler chickens. The ingredients included 3 samples of cereals (wheat, maize and sorghum), 6 samples of plant protein meals (soyabean meal, cottonseed meal, canola meal and sunflower meal) and 6 samples of animal protein meals (meat meal, meat-and-bone meal, feather meal and fish meal). 2. The test ingredients were incorporated as the sole source of dietary protein in assay diets. Each diet was offered ad libitum to 3 pens (4 birds/pen) from d 35 to d 42 post-hatching. Total collection of excreta was carried out during the last 4 d. All birds were killed on d 42 and the contents of the lower half of the ileum were collected. Apparent ileal and excreta amino acid digestibilities were calculated using acid-insoluble ash as the indigestible marker. 3. The influence of site of measurement was found to vary among food ingredients, among samples within an ingredient and among different amino acids within an ingredient. Ileal amino acid digestibility values were similar in some ingredients, but significantly lower or higher in others than the corresponding excreta values. 4. Average ileal and excreta amino acid digestibilities in sorghum and maize were similar, but significant differences were observed for individual amino acids. In contrast, ileal amino acid digestibility values were higher than the corresponding excreta digestibility values in wheat. 5. The average ileal and excreta digestibilites of amino acids in the 3 soyabean meal samples were similar although small, but significant differences were noted for individual amino acids. Site of measurement had no effect on the digestibility of amino acids in canola meal. Digestibilities of valine, isoleucine, phenylalanine, histidine, glutamic acid, alanine and tyrosine in sunflower meal and those of valine, methionine, isoleucine, leucine, lysine, glutamic acid and alanine in cottonseed meal were lower by excreta analysis. 6. Digestibilities in animal protein meals, with the exception of blood meal and fish meal, were consistently higher by excreta analysis. Ileal-excreta differences in individual amino acid digestibilities were more evident in feather meal, meat meal and meat-and-bone meal. 7. Threonine and valine were the indispensable amino acids that were more frequently influenced by the site of measurement. Of the dispensable amino acids, aspartic acid, serine, glutamic acid and alanine were the most affected. 8. Differences determined between ileal and excreta digestibilities in the present study clearly demonstrate that amino acid metabolism by hindgut microflora in chickens may be substantial and that digestibilities measured in the terminal ileum are more accurate measures of amino acid availability than those measured in the excreta.

Amino Acids↗
PubMed1999

Influence of microbial phytase on apparent ileal amino acid digestibility of feedstuffs for broilers.

The influence of microbial phytase on the ileal amino acid digestibilities in three cereals (corn, sorghum, and wheat), four oilseed meals (soybean meal, canola meal, cottonseed meal, and sunflower meal) and two cereal by-products (wheat middlings and rice polishings) was determined using 5-wk-old broilers. Supplementation of microbial phytase (1,200 FTU/kg) improved (P < 0.001 to 0.10) the digestibilities of protein and amino acids in all feedstuffs, but the magnitude of response varied depending on the feedstuff and the amino acid considered. Mean digestibility of the 15 amino acids in the feedstuffs without and with phytase were: corn, 78.0 and 80.4%; sorghum, 74.7 and 79.4%; wheat, 77.7 and 84.6%; soybean meal, 82.2 and 85.5%; canola meal, 78.7 and 80.7%; cottonseed meal, 70.8 and 74.2%; sunflower meal, 76.7 and 80.2%; wheat middlings, 70.8 and 73.4%; and rice polishings 62.1 and 66.9%, respectively. When individual amino acids were considered, the increments in digestibility were relatively higher for threonine and valine. This effect was consistent across all feedstuffs. The observed variations in response among feedstuffs were influenced by the inherent protein digestibility, but not by dietary phytic acid concentration. No correlations were determined between the dietary concentrations of phytic acid and phytase responses in terms of protein digestibility (r = 0.20; P > 0.31) and mean amino acid digestibility (r = 0.12; P > 0.51); however a significant negative correlation was observed between inherent protein digestibility and phytase responses in protein digestibility (r = -0.42; P < 0.03). It appears that solubilities of phytate salts and protein, and their influence on the degree of phytate-protein complexing in different feedstuffs, may be more relevant than total phytic acid concentrations. Interestingly, dietary phytic acid concentrations were negatively correlated with inherent protein (r = -0.81; P < 0.001) and mean amino acid (r = -0.85; P < 0.001) digestibilities of the feedstuffs evaluated in this study.

6-Phytase↗
PubMed1994

Nutritional assessment of yam (Dioscorea alata) tubers.

The nutrient and antinutrient components of tubers from seven cultivars of Dioscorea alata were determined. The average crude protein content of D. alata tubers was 7.4%. Starch (75.6-84.3%) was the predominant fraction of the tuber dry matter. Significant differences in crude protein and starch contents were observed among cultivars. Vitamin C content of the yam tubers ranged from 13.0 to 24.7 mg/100 g fresh weight. The results showed yams to be reasonably good sources of minerals. Phytic acid contents of the yams were low, with values ranging from 58.6 to 198.0 mg/100 g dry matter. Total oxalate levels in yam tubers were found to be in the range of 486-781 mg/100 g dry matter, but may not constitute a nutritional concern since 50-75% of the oxalates were in the water-soluble form. The overall results are suggestive of the nutritional superiority of yams compared to other tropical root crops.

Minerals↗
PubMed1993

Physical and biochemical properties of green banana flour.

Banana flour prepared from two cooking banana varieties, namely 'Alukehel' and 'Monthan', were evaluated for their physical and biochemical characteristics. The yields of flour averaged 31.3% for 'Alukehel' and 25.5% for 'Monthan'. The pH of the flour ranged from 5.4 to 5.7. The bulk density and particle size distribution were also measured. The average chemical composition (% dry matter) of the flours were as follows: crude protein, 3.2; crude fat, 1.3; ash, 3.7; neutral detergent fiber, 8.9; acid detergent fiber, 3.8; cellulose, 3.1; lignin, 1.0 and hemicellulose, 5.0. Carbohydrate composition indicated the flour to contain 2.8% soluble sugars, 70.0% starch and 12.0% non-starch polysaccharides. Potassium is the predominant mineral in banana flour. Fresh green banana is a good source of vitamin C, but almost 65% is lost during the preparation of flour. Oxalate content (1.1-1.6%) of banana flour is probably nutritionally insignificant. The overall results are suggestive of the potential of green bananas as a source of flour.

Ascorbic Acid↗