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Biomedical subjects

S Venkataraman

Publications and source records attributed to S Venkataraman.

At least 19 recordsLinked to original sources
PubMed2006

Automated image analysis of atomic force microscopy images of rotavirus particles.

A variety of biological samples can be imaged by the atomic force microscope (AFM) under environments that range from vacuum to ambient to liquid. Generally imaging is pursued to evaluate structural features of the sample or perhaps identify some structural changes in the sample that are induced by the investigator. In many cases, AFM images of sample features and induced structural changes are interpreted in general qualitative terms such as markedly smaller or larger, rougher, highly irregular, or smooth. Various manual tools can be used to analyze images and extract more quantitative data, but this is usually a cumbersome process. To facilitate quantitative AFM imaging, automated image analysis routines are being developed. Viral particles imaged in water were used as a test case to develop an algorithm that automatically extracts average dimensional information from a large set of individual particles. The extracted information allows statistical analyses of the dimensional characteristics of the particles and facilitates interpretation related to the binding of the particles to the surface. This algorithm is being extended for analysis of other biological samples and physical objects that are imaged by AFM.

Algorithms↗
PubMed2006

Measuring cell surface elasticity on enteroaggregative Escherichia coli wild type and dispersin mutant by AFM.

Enteroaggregative Escherichia coli (EAEC) is pathogenic and produces severe diarrhea in humans. A mutant of EAEC that does not produce dispersin, a cell surface protein, is not pathogenic. It has been proposed that dispersin imparts a positive charge to the bacterial cell surface allowing the bacteria to colonize on the negatively charged intestinal mucosa. However, physical properties of the bacterial cell surface, such as rigidity, may be influenced by the presence of dispersin and may contribute to pathogenicity. Using the system developed in our laboratory for mounting and imaging bacterial cells by atomic force microscopy (AFM), in liquid, on gelatin coated mica surfaces, studies were initiated to measure cell surface elasticity. This was carried out in both wild type EAEC, that produces dispersin, and the mutant that does not produce dispersin. This was accomplished using AFM force-distance (FD) spectroscopy on the wild type and mutant grown in liquid or on solid medium. Images in liquid and in air of both the wild-type and mutant grown in liquid and on solid media are presented. This work represents an initial step in efforts to understand the pathogenic role of the dispersin protein in the wild-type bacteria.

Agar↗
PubMed2006

Studies on hepatoprotective and antioxidant actions of Strychnos potatorum Linn. seeds on CCl4-induced acute hepatic injury in experimental rats.

Strychnos potatorum Linn. seeds are used in the Indian traditional system of medicine for the treatment of hepatopathy, nephropathy, gonorrhoea, leucorrhoea, gastropathy, bronchitis, chronic diarrhoea, strangury, renal and vesicle calculi, diabetes and eye diseases. The present study describes the hepatoprotective and antioxidant activities of the seed powder (SPP) and aqueous extract (SPE) of Strychnos potatorum seeds against CCl4-induced acute hepatic injury. Hepatic injury was achieved by injecting 3 ml/kg, s.c. of CCl4 in equal proportion with olive oil. Both SPP and SPE at the doses 100 and 200 mg/kg, p.o. offered significant (p < 0.001) hepatoprotective action by reducing the serum marker enzymes like serum glutamate oxaloacetate transaminase (SGOT) and serum glutamate pyruvate transaminase (SGPT). They also reduced the elevated levels of ALP and serum bilirubin. Reduced enzymic and nonenzymic antioxidant levels and elevated lipid peroxide levels were restored to normal by administration of SPP and SPE. Histopathological studies further confirmed the hepatoprotective activity of SPP and SPE when compared with the CCl4 treated control groups. The results obtained were compared with Silymarin (50 mg/kg, p.o.), the standard drug. In conclusion, SPE (200 mg/kg, p.o.) showed significant hepatoprotective activity similar to that of the standard drug, Silymarin (50 mg/kg, p.o.).

Animals↗
PubMed2006

Tropical malabsorption.

Malabsorption is an important clinical problem both in visitors to the tropics and in native residents of tropical countries. Infections of the small intestine are the most important cause of tropical malabsorption. Protozoal infections cause malabsorption in immunocompetent hosts, but do so more commonly in the setting of immune deficiency. Helminth infections occasionally cause malabsorption or protein-losing enteropathy. Intestinal tuberculosis, chronic pancreatitis and small-bowel bacterial overgrowth are important causes of tropical malabsorption. In recent years, inflammatory bowel disease and coeliac disease have become major causes of malabsorption in the tropics. Sporadic tropical sprue is still an important cause of malabsorption in adults and in children in South Asia. Investigations to exclude specific infective, immunological or inflammatory causes are important before considering tropical sprue as a diagnosis. This article briefly reviews the management of tropical sprue and presents an algorithm for its investigation and management.

Bacterial Infections↗
PubMed2005

Hepatoprotective and antioxidant effects of Hygrophila auriculata (K. Schum) Heine Acanthaceae root extract.

Hygrophila auriculata (K. Schum) Heine (syn. Asteracantha longifolia Nees, Acanthaceae) was widely used in the Indian systems of medicine for the treatment of various liver ailments. The hepatoprotective activity of the aqueous extract of the roots was studied on CCl(4)-induced liver toxicity in rats. The activity was assessed by monitoring the various liver function tests, viz. alanine transaminase, aspartate transaminase (AST), alkaline phosphatase (ALP), total protein and total bilirubin. Furthermore, hepatic tissues were subjected to histopathological studies. The root extract was also studied for its in vitro antioxidant activity using ferric thiocyanate (FTC) and thiobarbituric acid (TBA) methods. The extract exhibited significant hepatoprotective and antioxidant activities.

Acanthaceae↗
PubMed2005

Anti-inflammatory activity of Justicia prostrata gamble in acute and sub-acute models of inflammation.

In this study, the aqueous (AQJP) and alcoholic (ALJP) extracts of the whole plant of Justicia prostrata Gamble (Acanthaceae) were screened for their acute and subacute anti-inflammatory activities using carrageenan-induced acute inflammation and cotton-pellet-induced granuloma (subacute inflammation), respectively, in rats. In the carrageenan-induced rat paw oedema model, both extracts were found to exhibit maximum reduction in paw volume at the first hour in a dose-dependent manner. At the dose of 500 mg/kg p.o., both extracts AQJP and ALJP showed maximum inhibition (51.39% and 62.5%, respectively) in rat paw oedema volume at the first hour of carrageenan-induced acute inflammation. In the cotton pellet granuloma assay, AQJP and ALJP at the dose of 500 mg/kg p.o. suppressed the transudative, exudative and proliferative phases of chronic inflammation. These extracts were able to (i) reduce the lipid peroxide content of exudates and liver and (ii) normalize the increased activity of acid and alkaline phosphatases in serum and liver of cotton pellet granulomatous rats. Preliminary phytochemical screening revealed the presence of lignans, triterpenes and phenolic compounds in ALJP, whereas phenolic compounds and glycosides in AQJP. The anti-inflammatory properties of these extracts may possibly be due to the presence of phenolic compounds. The anti-inflammatory effects produced by the extracts at the dose of 500 mg/kg, p.o. was comparable with the reference drug diclofenac sodium (5 mg/kg p.o.).

Acanthaceae↗
PubMed2005

Antiulcerogenic effect of Justicia prostrata Gamble.

Antiulcerogenic effect of the alcoholic (ALJP) and aqueous (AQJP) extracts of the whole plant of Justicia prostrata was studied in aspirin+pylorus ligated rat models and analysed for gastric volume, ulcer index, free and total acidity. Biochemical parameters like total proteins, total hexoses, hexosamine, fucose and sialic acid were also estimated. Both extracts (ALJP and AQJP) significantly reduced both the gastric volume and the acidity of gastric juice. It also significantly promoted gastric mucus secretion by increasing total carbohydrates and decreasing the protein concentration in aspirin+ pylorus ligated rats. The results suggest that both the extracts (ALJP and AQJP) possess antiulcer activity, whereas AQJP is more effective when compared with ALJP in aspirin+pylorus ligated rat models. The results were compared with the standard drug Rantidine, a H2 receptor antagonist.

Acanthaceae↗
PubMed2005

Hyperglycaemia as an indicator of concurrent acute pancreatitis in fulminant hepatic failure associated with hepatitis B infection.

Pancreatitis occurring concurrently with fulminant hepatic failure (FHF) is primarily detected on autopsy and is seldom clinically apparent. We report a fatal case of FHF in a 25-year-old woman which was related to acute hepatitis B infection. In this patient, hyperglycaemia needing insulin infusions led to the detection of acute pancreatitis. FHF complicated by acute pancreatitis has a poor prognosis. A high index of suspicion is necessary for its diagnosis. The role of orthotopic liver transplantation and use of antiviral therapies need further evaluation in this situation.

Acute Disease↗
PubMed2003

Evaluation of anti-diarrhoeal activity in seed extracts of Mangifera indica.

Mangifera indica is commonly grown in many parts of the world. Its seeds have been used for anti-diarrhoeal activity in Indian traditional medicine. This study evaluates the potential anti-diarrhoeal activity of methanolic (MMI) and aqueous (AMI) extracts of seeds of M. indica in experimental diarrhoea, induced by castor oil and magnesium sulphate in mice. Both MMI and AMI were given orally in the dose of 250 mg/kg, showed significant anti-diarrhoeal activity comparable with that of the standard drug loperamide. However, only MMI significantly reduced intestinal transit in charcoal meal test as compared with atropine sulphate (5 mg/kg; im). The in vitro antimicrobial activity of MMI and AMI showed variable results. While, AMI significantly inhibited growth of Streptococcus aureus and Proteus vulgaris, both MMI and AMI did not show any significant effect on growth of E. coli and Klebsiella. The results illustrate that the extracts of M. indica have significant anti-diarrhoeal activity and part of the activity of MMI may be attributed to its effect on intestinal transit.

Animals↗
PubMed2003

Faecal lactoferrin as a predictor of positive faecal culture in south Indian children with acute diarrhoea.

Faecal lactoferrin, an iron-based glycoprotein found concentrated in secondary granules of neutrophils, may serve as a surrogate marker of inflammation in the intestine. We evaluated the usefulness of faecal lactoferrin as a predictor of infection with invasive enteropathogens in 262 children with diarrhoea. Lactoferrin at a dilution of 1:50 had the highest sensitivity for detection not only of conventionally cultured invasive enteropathogens but also of all other enteropathogens. Neither individual clinical symptoms nor the identification of faecal leucocytes by microscopy significantly predicted isolation of invasive enteropathogens from the faeces of children with diarrhoea. Faecal lactoferrin is a simple test which showed promise in predicting which children with diarrhoea are likely to be infected with invasive pathogens and can be incorporated as a screening test before faecal cultures are undertaken in this population.

Acute Disease↗
PubMed2003

Assessing the severity of hepatic encephalopathy.

The diagnosis of hepatic encephalopathy (HE) is based mostly on clinical criteria. It is important to assess the severity of HE quantitatively for both clinical practice and research; however, this remains a difficult and challenging problem. Modalities like psychometric tests, electroencephalography, evoked potentials, and several innovative biochemical indices have shown promise in this regard. No single parameter or index has yet been shown to be infallible in assessing the severity of HE.

Ammonia↗
PubMed2000

Detailed methods for the quantification of nitric oxide in aqueous solutions using either an oxygen monitor or EPR.

The interest in nitric oxide has grown with the discovery that it has many biological functions. This has heightened the need for methods to quantify nitric oxide. Here we report two separate methods for the quantification of aqueous stock solutions of nitric oxide. The first is a new method based on the reaction of nitric oxide with oxygen in liquid phase (*NO + O2 + 2H2O --> 4HNO2); an oxygen monitor is used to measure the consumption of oxygen by nitric oxide. This method offers the advantages of being both simple and direct. The presence of nitrite or nitrate, frequent contaminants in nitric oxide stock solutions, does not interfere with the quantification of nitric oxide. Measuring the disappearance of dissolved oxygen, a reactant, in the presence of known amounts of nitric oxide has provided verification of the 4:1 stoichiometry of the reaction. The second method uses electron paramagnetic resonance spectroscopy (EPR) and the nitric oxide trap [Fe2+-(MGD)2], (MGD = N-methyl-D-glucamine dithiocarbamate). The nitrosyl complex is stable and easily quantitated as a room temperature aqueous solution. These two methods are validated with Sievers 280 Nitric Oxide Analyzer and cross-checked with standards using UV-Vis spectroscopy. The practical lower limits for measuring the concentration of nitric oxide using the oxygen monitor approach and EPR are approximately 3 microM and 500 nM, respectively. Both methods provide straightforward approaches for the standardization of nitric oxide in solution.

Electron Spin Resonance Spectroscopy↗
PubMed2000

The plant vacuolar sorting receptor AtELP is involved in transport of NH(2)-terminal propeptide-containing vacuolar proteins in Arabidopsis thaliana.

Many soluble plant vacuolar proteins are sorted away from secreted proteins into small vesicles at the trans-Golgi network by transmembrane cargo receptors. Cleavable vacuolar sorting signals include the NH(2)-terminal propeptide (NTPP) present in sweet potato sporamin (Spo) and the COOH-terminal propeptide (CTPP) present in barley lectin (BL). These two proteins have been found to be transported by different mechanisms to the vacuole. We examined the ability of the vacuolar cargo receptor AtELP to interact with the sorting signals of heterologous and endogenous plant vacuolar proteins in mediating vacuolar transport in Arabidopsis thaliana. AtELP extracted from microsomes was found to interact with the NTPPs of barley aleurain and Spo, but not with the CTPPs of BL or tobacco chitinase, in a pH-dependent and sequence-specific manner. In addition, EM studies revealed the colocalization of AtELP with NTPP-Spo at the Golgi apparatus, but not with BL-CTPP in roots of transgenic Arabidopsis plants. Further, we found that AtELP interacts in a similar manner with the NTPP of the endogenous vacuolar protein AtALEU (Arabidopsis thaliana Aleu), a protein highly homologous to barley aleurain. We hypothesize that AtELP functions as a vacuolar sorting receptor involved in the targeting of NTPP-, but not CTPP-containing proteins in Arabidopsis.

Arabidopsis↗
PubMed2000

Amylase-resistant starch plus oral rehydration solution for cholera.

BACKGROUND: Although standard glucose-based oral rehydration therapy corrects the dehydration caused by cholera, it does not reduce the diarrhea. Short-chain fatty acids, which are produced in the colon from nonabsorbed carbohydrates, enhance sodium absorption. We conducted a study to determine the effects of an orally administered, nonabsorbed starch (i.e., one resistant to digestion by amylase) on fecal fluid loss and the duration of diarrhea in patients with cholera. METHODS: We randomly assigned 48 adolescents and adults with cholera to treatment with standard oral rehydration therapy (16 patients), standard therapy and 50 g of rice flour per liter of oral rehydration solution (16 patients), or standard therapy and 50 g of high-amylose maize starch, an amylase-resistant starch, per liter of oral rehydration solution (16 patients). The primary end points were fecal weight (for every 12-hour period during the first 48 hours after enrollment) and the length of time to the first formed stool. RESULTS: The mean (+/-SD) fecal weights in the periods 12 to 24 hours, 24 to 36 hours, and 36 to 48 hours after enrollment were significantly lower in the resistant-starch group (2206+/-1158 g, 1810+/-1018 g, and 985+/-668 g) than in the standard-therapy group (3251+/-766 g, 2621+/-1149 g, and 2498+/-1080 g; P=0.01, P= 0.04, and P=0.001, respectively). From 36 to 48 hours after enrollment, fecal weight was also significantly lower with the resistant-starch therapy than with the rice-flour therapy (985+/-668 g vs. 1790+/-866 g, P=0.01). The mean duration of diarrhea was significantly shorter with the resistant-starch therapy (56.7+/-18.6 hours) than with standard therapy alone (90.9+/-29.8 hours, P=0.001) or the rice-flour therapy (70.8+/-20.2 hours, P=0.05). Fecal excretion of starch was higher with the resistant-starch therapy (32.6+/-30.4) than with the standard therapy (11.7+/-4.1 g, P=0.002) or the rice-flour therapy (15.1+/-8.4 g, P=0.01). CONCLUSIONS: The addition of a resistant starch to oral rehydration solution reduces fecal fluid loss and shortens the duration of diarrhea in adolescents and adults with cholera.

Adolescent↗
PubMed2000

Energy expenditure in critically ill children.

OBJECTIVES: To measure energy expenditure in critically ill children and compare it with the energy expenditure predicted by recommended formulas, and relate the measured energy expenditure to nutritional and clinical indices. DESIGN: A prospective, clinical study. SETTING: Tertiary care pediatric intensive care unit in a university children's hospital. PATIENTS: A total of 37 patients with critical illness who were mechanically ventilated for > or =24 hrs were studied. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Chronic protein-energy malnutrition (CPEM) and acute protein-energy malnutrition were defined by the Waterlow's stages and fat and protein stores were classified as defined by Frisancho, Ryan, and Martinez. Severity of illness was assessed by the Pediatric Risk of Mortality Score, the Therapeutic Intervention Scoring System, and indices of organ failure. Oxygen consumption, carbon dioxide production, and the respiratory quotient were measured by indirect calorimetry, and energy expenditure (MEE) was calculated using the modified Weir formula. Resting energy expenditure (PBMR), predicted energy expenditure, and caloric intake were calculated using recommended formulas. A total of 77 measurements were made in 37 children. MEE was significantly lower than PBMR as estimated by all equations except the Talbot equations. MEE was significantly lower than predicted energy expenditure and the recommended daily allowances. On the first day, the MEE/PBMR ratio was <0.9 in 56.8%, 0.9-1.1 in 21.6%, and >1.1 in 21.6% of patients. MEE did not differ significantly among disease groups or between medical and surgical patients. There was no difference in MEE with or without neuromuscular blockade. MEE was lower in the presence of multiple organ system failure (MOSF) (1019 + 166 kcal/m2 without MOSF vs. 862 + 241 with MOSF; p = .025). A total of 21% had CPEM and 8.1% had acute protein-energy malnutrition. Multivariate stepwise regression analysis showed that the protein intake, midarm muscle area, midarm fat area, the use of vasoactive agents, and sedation correlated with MEE (p < .05). With CPEM, MEE was correlated to the severity of illness (p < .05). Patients at risk for protein stores depletion (midarm muscle areas 1 and 2) had a higher incidence of MOSF compared with nutritionally normal children (p < .05), whereas patients with fat stores depletion (midarm fat area 2) had a higher probability of death (50% vs. 6%, respectively). CONCLUSIONS: Recommended daily allowances and energy expenditure predicted by using a stress-related correction to the resting energy expenditure grossly overestimate MEE. MEE is close to PBMR and in many patients, it is lower than PBMR. MEE that is lower than PBMR is associated with a higher morbidity. Nutritional repletion should thus be based on MEE to avoid the problems of over- or underfeeding.

Acute Disease↗
PubMed1999

Basal ganglia calcification.

Basal ganglia calcification (BGC) is now being diagnosed with increasing frequency with widespread application of computed tomography (CT) in clinical practice and is no more considered a rarity. During the period 1987 to 1995, 42 patients were noted to have BGC and it constituted 0.93% of all CT scan of brain carried out during the relevant period. These patients presented with diverse neurological and endocrine disorders i.e., epilepsy (22 patients), mental retardation (five patients), extra-pyramidal syndromes (five patients), abnormal behaviour (three patients), stroke (two patients), raised intracranial tension without localizing signs (one patient), following radiotherapy (one patient), and with hypoparathyroidism (three patients). These patients were noted to have variable degree of calcification in different parts of brain i.e., basal ganglia (42 cases), cerebellum (12 cases) and cerebral cortex (nine cases). Family history of a neurological disorder was available in five patients. This study highlights the fact that calcification of basal ganglia and other parts of the brain is often a nonspecific finding on CT scan and it may not be possible to establish a clinicopathological correlation.

Adolescent↗
PubMed1999

Acinetobacter meningitis following head trauma.

A case of acinetobacter meningitis following head injury in a patient who developed cerebrospinal fluid otorrhea, and did not have any neurosurgical procedure, is presented. Previously reported cases are cited, with a review of the literature. Pefloxacin monotherapy is associated with a poor clinical response.

Acinetobacter Infections↗