PubMed Health⌕ Search

Biomedical subjects

D Prasad

Publications and source records attributed to D Prasad.

At least 19 recordsLinked to original sources
PubMed2006

Direct electron transfer with yeast cells and construction of a mediatorless microbial fuel cell.

The direct electron transfer exhibited by the yeast cells, Hansenula anomala has been demonstrated using the electrochemical technique cyclic voltammetry by immobilizing the microorganisms by two different methods viz., physical adsorption and covalent linkage. The analysis of redox enzymes present in the outer membrane of the microorganisms has been carried out in this work. This paper demonstrates that yeast cells with redox enzymes present in their outer membrane are capable of communicating directly with the electrode surface and contribute to current generation in a mediatorless biofuel cells. The efficiency of current generation has been evaluated using three anode materials.

Bioelectric Energy Sources↗
PubMed2006

Progressive resistance exercise for people with multiple sclerosis.

PURPOSE: This study aimed to determine if participation in a progressive resistance exercise (PRE) programme can: (1) increase the ability to generate maximal muscle force, (2) increase muscle endurance, (3) increase functional activity, and (4) improve overall psychological function of people with multiple sclerosis (MS). METHODS: A pre-post single group research design with a 4-week baseline familiarisation phase was used. Nine people (mean age 45.6 years, SD 10.7) with MS attended a gymnasium three times over 4 weeks for familiarization. Participants then completed a twice-weekly 10-week PRE programme, with two sets of 10 - 12 repetitions of each exercise. Outcome measures of muscle strength (1RM for arms and legs), muscle endurance (repetitions at half 1RM), walking speed, the 2-min walk test (2MWT), a timed stairs test, and the impact of MS on physical and psychological function were taken at weeks 2, 4, and 14. RESULTS: Participants attended 94.3% (SD 8.2%) of the training sessions, with no adverse events. After accounting for baseline stability, significant improvements (P < 0.05) were found in arm strength (14.4%), leg endurance (170.9%), fast walking speed (6.1%), and there was a trend for increased distance in the 2MWT (P = 0.06). The perceived impact of MS on physical function was reduced (P = 0.02). CONCLUSIONS: Adults with MS benefited from a PRE programme by improving muscle performance and physical activities, without adverse events. These findings suggest that PRE may be a feasible and useful fitness alternative for people with mild to moderate disability due to MS.

Adult↗
PubMed2006

A qualitative analysis of a progressive resistance exercise programme for people with multiple sclerosis.

PURPOSE: This qualitative study explored the perceptions of adults with multiple sclerosis about the positive and negative effects of a progressive resistance strengthening programme; and identified factors that might facilitate or create barriers to participation. METHODS: Seven women and two men (mean age 45.6 years, SD 10.7) with multiple sclerosis participated in a 10-week gymnasium based progressive resistance strengthening programme held twice a week. Participants were interviewed at the end of the programme. The recorded interviews were transcribed and then independently coded by three researchers. From these codes, the main themes emerged. RESULTS: Reports about the programme were very positive with physical, psychological and social benefits noted. Most participants said that they had less fatigue as a result of the programme. Few negative outcomes were reported and these were minor such as aches and pains. Key extrinsic factors for programme completion were the leaders' encouragement and knowledge of exercise; and the group aspect of the programme. Key intrinsic factors were enjoyment, determination, seeing the signs of progress, and a previously held positive attitude about the benefits of exercise. CONCLUSIONS: The results of this study suggest that progressive resistance strength training is a feasible fitness option for some people with multiple sclerosis. Factors perceived to be important for programme completion suggest that choosing encouraging leaders with knowledge of exercise, and exercising in a group may contribute to programme success.

Adult↗
PubMed2006

A biological process that reduces metals in municipal sludge to yield sulphur enhanced biosolids.

Heavy metal contamination can often restrict or prohibit land application of municipal sludge. In the present investigation a continuous biological process with powdered elemental sulphur as energy source was examined for solubilization of metals from anaerobically digested municipal sludge. The results showed that the continuous process can be designed to achieve both metal solubilization and efficient sulphur utilization. With a sulphur addition of 1.5 g l(-1) and an HRT of 14 days, solubilization efficiencies of 50, 33, 48, and 74% were obtained for cadmium, copper, nickel, and zinc, and about 80% of the added sulphur was oxidized. Addition of ferrous sulphate as an additional energy source did not improve the performance of the process. The residual sulphur in the metal decontaminated biosolids was in balance with the phosphorus content, potentially making it an effective sulphur fertilizer for soils deficient in the nutrient.

Biodegradation, Environmental↗
PubMed2006

Biosolids from two-stage bioleaching could produce compost for unrestricted use.

A biological process, called BIOSOL, developed in our laboratory, efficiently reduces metals and reduces pathogenic indicator bacteria in sewage sludges in a single-stage system to levels meeting Ontario Ministry of the Environment (OME) requirements for land application of biosolids. Since the requirements for unrestricted use of compost are 10 to 50 times (depending on the metal involved) more restrictive than those for land application, this study was carried out to determine whether the efficiency of the BIOSOL system could be increased to meet the more stringent limitations required for compost. A two-stage modified BIOSOL system was successfully operated for a period of 4% months, at 30 degrees C, treating anaerobically digested sludge from the Guelph Wastewater Treatment Plant. Elemental sulphur (4g l(-1)) was the energy source for the autotrophic bacteria (thiobacilli). The pH, metals (Cd, Cr, Cu, Pb and Zn), and sulphate were used to evaluate system effectiveness. At an HRT of 8 days in each solubilization tank, and a S*-concentration of 4g l(-1), sulphur oxidation efficiency was about 70%, while the metal removals were: Cd 90%, Cr 93%, Cu 96%, Pb 67% and Zn 98%. The finished product (biosolids) met the OME requirements for metal concentrations for producing compost or fertilizer for unrestricted use. The reduction of pathogenic indicator organisms was demonstrated in earlier studies.

Biodegradation, Environmental↗
PubMed2005

Cytoprotective and antioxidant activity of Rhodiola imbricata against tert-butyl hydroperoxide induced oxidative injury in U-937 human macrophages.

The present study reports cytoprotective and antioxidant activity of aqueous and alcoholic extracts of Rhodiola imbricata rhizome on tert-butyl hydroperoxide (tert-BHP) induced cytotoxicity in U-937 human macrophages. There was an increase in cytotoxicity and apoptosis significantly in the presence of tert-BHP over control cells. The tert-BHP induced cytotoxicity can be attributed to enhanced reactive oxygen species (ROS) production which in turn is responsible for fall in reduced glutathione (GSH) levels; further there was a significant decrease in mitochondrial potential and increase in apoptosis and DNA fragmentation. Both aqueous and alcoholic extracts of Rhodiola rhizome at a concentration of 250 microg/ml were found to inhibit tert-BHP induced free radical production, apoptosis and to restore the anti-oxidant levels to that of the control cells. The alcoholic extract of Rhodiola showed higher cytoprotective activities than aqueous extract. These observations suggest that the alcoholic and aqueous extracts of Rhodiola have marked cytoprotective and antioxidant activities.

Antioxidants↗
PubMed2004

Targeted cybridization in citrus: transfer of Satsuma cytoplasm to seedy cultivars for potential seedlessness.

CMS (cytoplasmic male sterility) can be controlled by the mitochondrion genome in higher plants, including Satsuma mandarin. Somatic fusion experiments in citrus combining embryogenic callus protoplasts of one parent with leaf protoplasts of a second parent often produce cybrid plants of the leaf parent, a phenomenon occurring most often with interspecific fusion combinations. In an attempt to practically exploit this cybridization phenomenon, we conducted somatic fusion experiments combining embryogenic suspension-derived protoplasts of Satsuma mandarin, Citrus unshiu Marc. cv. Guoqing No. 1 (G1), a male-sterile cultivar, with leaf protoplasts of other seedy types--Hirado Buntan Pink pummelo (HBP) [Citrus grandis (L.) Osbeck], Sunburst mandarin (C. reticulata Blanco), Orie Lee hybrid (C. reticulata cv. Clementine x Murcott tangor), and Murcott tangor [C. reticulata x C. sinensis (L.) Osbeck], respectively--in an attempt to generate seedless cybrids by the targeted transfer of CMS. The genetic identities of regenerated plants from all four parental combinations were determined by flow cytometry, SSR, CAPS (or PCR-RFLP), RFLP, and chloroplast-SSR analyses. Regenerated plants from the first three parental combinations were diploids, and the cybrid nature of G1 + HBP with the mitochondrion genome from G1 and the chloroplast genome from HBP was confirmed, whereas the cybrid nature of the remaining two combinations was difficult to confirm because of the close phylogenetic relatedness of both fusion parents, as expected. Plants from G1 + Murcott were confirmed as tetraploid somatic hybrids. This is the first report of targeted citrus cybrid production by symmetric fusion with male-sterile Satsuma as the callus parent and other seedy cultivars as the leaf parents.

Cell Fusion↗
PubMed2004

Intracranial subfrontal schwannoma treated with surgery and 3D conformal radiotherapy.

Subfrontal schwannoma not arising from the cranial nerves are rare tumors. A 19-year-old man presented with a large subfrontal extra-axial enhancing mass with a preoperative diagnosis of skull base meningioma. A subtotal resection of the tumor mass was carried out. Microscopic examination revealed it to be a schwannoma. The residual tumor was treated with fractionated three-dimensional conformal radiotherapy (3D CRT). The rationale of treating with radiotherapy in such cases is analyzed.

Adult↗
PubMed2001

Cytoprotective and immunomodulatory properties of Geriforte, a herbomineral preparation, in lymphocytes.

The study was designed to determine the cytoprotective and immunomodulatory properties of Geriforte, an indigenous herbomineral compound, using lymphocytes as a model system. The possible involvement of free radicals and the ability of Geriforte to inhibit the oxidative process induced by tert-butylhydroperoxide (tert-BHP) was also investigated. The production of free radicals (evaluated by fluorescent probe fluorescein-diacetate), level of malondialdehyde (MDA, as index of lipid peroxidation), and levels of anti-oxidants--reduced glutathione (GSH) and glutathione peroxidase (GPx) were determined. There was an increase in cytotoxicity and apoptosis significantly in the presence of tert-BHP (100 microM) over control. Addition of tert-BHP resulted in a marked increase in free radical production and MDA level with a concomitant decrease in GSH level in lymphocytes. Geriforte supplementation reduced cytotoxicity and apoptosis induced by tert-BHP. Further, Geriforte inhibited tert-BHP induced lipid peroxidation and maintained higher anti-oxidant levels. tert-BHP significantly inhibited the lymphocyte proliferation stimulated by mitogens (Lipopolysaccharide/Concanavalin A) and enhanced DNA fragmentation. Geriforte relieved the inhibitory effect of tert-BHP on lymphocyte proliferation and decreased DNA fragmentation appreciably. The results indicate that Geriforte possesses cytoprotective and immunomodulatory properties which could be due to its anti-oxidant activity.

Adjuvants, Immunologic↗
PubMed2001

Reduction of indicator organisms during biological solubilization of metals: a pilot study.

Laboratory and pilot scale studies on the biological solubilization of metals from undigested raw sludge were carried out using elemental sulphur as the energy source. Metals (Cu, Zn, Ni and Cd), pH, sulfate and indicator bacteria [total coliforms (TC) faecal coliforms (FC) and faecal streptococci (FS)] were used to evaluate the system effectiveness. This paper does not report the detailed design and operational data of the pilot plant (available elsewhere [1]) but focuses on the biological tests carried out at the Main Wastewater Treatment Plant in Toronto from July to December, 1997. Since the indicator bacteria are injured from exposure to low pH and potentially toxic metal concentrations, improved alternative methods for their enumeration and their ability to repair acid-metal induced injury in a resuscitation medium (CASO tryptone soya broth) were also investigated. Resuscitation was not effective in repairing cells injured during bacterial leaching. The MPN technique (using lauryl tryptose broth) for enumerating indicator bacteria (total coliforms) gave higher counts and was therefore superior to the spread plate technique (using m-Endo agar) in recovering bacteria from acidic leached sludge (biosolids). However, the coliform bacterial counts from raw sludge were similar by the two methods. This study indicated that the biological solubilization process could significantly reduce the pathogenic indicators. Concentrations of TC, FC and FS in the leached biosolids from the solubilization tank were lower than concentrations in the raw sludge by 4 to 6 orders of magnitude and the finished product (biosolids) met US. EPA requirements for pathogen and metal concentrations for Class A biosolids to be used on agricultural land.

Agriculture↗
PubMed2001

Anticonvulsant effects of gamma surgery in a model of chronic spontaneous limbic epilepsy in rats.

OBJECT: The management of intractable epilepsy remains a challenge, despite advances in its surgical and nonsurgical treatment. The identification of low-risk, low-cost therapeutic strategies that lead to improved outcome is therefore an important ongoing goal of basic and clinical research. Single-dose focal ionizing beam radiation delivered at necrosis-inducing and subnecrotic levels was investigated for its effects on seizure activity by using an established model of chronic recurrent spontaneous limbic seizures in rats. METHODS: A single 90-minute period of repetitive electrical stimulation (inducing stimulus) of the hippocampus in rats elicited a single episode of status epilepticus, followed by a 2- to 4-week seizure-free period. Spontaneous recurrent seizures developed subsequently and persisted for the duration of monitoring (2-10 months). Simultaneous computerized electroencephalography and video recording were used to monitor the animals. After the establishment of spontaneous recurrent seizures, bilateral radiation centered in the ventral hippocampal formation was administered with the Leksell gamma knife, aided by a stereotactic device custom made for small animals. A center dose of 10, 20, or 40 Gy was administered using a 4-mm collimator. Control animals were subjected to the same seizure-inducing stimulus but underwent a sham treatment instead of gamma irradiation. In a second experiment, the authors examined the effects of gamma irradiation on the proclivity of hippocampal neurons to display epileptiform discharges. Naive animals were irradiated with a single 40-Gy dose, as already described. Slices of the hippocampus were prepared from animals killed between 1 and 178 days postirradiation. Sensitivity to penicillin-induced epileptiform spiking was examined in vitro in slices prepared from control and irradiated rat brains. CONCLUSIONS: In the first experiment, single doses of 20 or 40 Gy (but not 10 Gy) reduced substantially, and in some cases eliminated, behaviorally and electrographically recognized seizures. Significant reductions in both the frequency and duration of spontaneous seizures were observed during a follow-up period of up to 10 months postradiation. Histological examination of the targeted region did not reveal signs of necrosis. These findings indicate that single-dose focal ionizing beam irradiation at subnecrotic dosages reduces or eliminates repetitive spontaneous seizures in a rat model of temporal lobe epilepsy. In the second experiment, synaptically driven neuronal firing was shown to be intact in hippocampal neurons subjected to 40-Gy doses. However, the susceptibility to penicillin-induced epileptiform activity was reduced in the brain slices of animals receiving 40-Gy doses, compared with those from control rats that were not irradiated. The results provide rational support for the utility of subnecrotic gamma irradiation as a therapeutic strategy for treating epilepsy. These findings also provide evidence that a functional increase in the seizure threshold of hippocampal neurons contributes to the anticonvulsant influence of subnecrotic gamma irradiation.

Animals↗
PubMed2001

Carbon monoxide poisoning.

OBJECTIVES: We studied the clinical profile and autopsy findings of carbon monoxide (CO) poisoning encountered at a hospital located at the altitude of 5,000 ft above mean sea level. METHODS: Clinical and postmortem findings in 25 and 15 cases of accidental CO poisoning respectively were evaluated. The diagnosis was made on circumstantial evidences, definite history of "Bukhari" burning and positive Kunkel's test for carboxyhaemoglobin (COHb). Detailed routine investigations including pulse oxymetry, X-ray chest and electrocardiographical monitoring was carried out in all the 25 patients. Oxygen (100%) via an endotracheal tube in all the comatosed patients and by conventional non-rebreathing plastic face masks was the mainstay of treatment. All patients were monitored and followed up for any delayed neurological sequelae. RESULTS: Most of the patients were young adults and the duration of exposure varied between three to eight hours. The initial diagnosis was stroke in three, seizure in one, encephalitis in two and ischaemic heart disease (IHD) in four. Neurological and respiratory signs and symptoms were noted in 19 and 18 of 25 patients respectively. SPO2 measured by pulse oxymetry was normal in all cases. ECG was suggestive of IHD in four patients. No delayed neurological sequelae was noted in any patients. Autopsy revealed deep red discoloration of skin and serous membranes in 80%, pulmonary oedema in 100% and cerebral oedema with widespread multiple pin point haemorrhages mainly in thalamus and globus pallidus in 40%. CONCLUSION: A high level of suspicion and routine history about the kind of indoor heating, specially in cold climate areas during winter will help in early diagnosis and decrease the incidence of misdiagnosis of CO poisoning. Oxygen (100%) or hyperbaric oxygen, if available should be administered without waiting for COHb levels to decrease morbidity and mortality.

Adolescent↗
PubMed2001

Effect of vitamin E supplementation on hypoxia-induced oxidative damage in male albino rats.

BACKGROUND: There is growing evidence that free radicals mediated oxidative injury due to inadequate oxygen availability is an important factor in various pathologies at high altitude. Since vitamin E is known to protect the cells from oxidative damage due to its potent antioxidant properties, the present study was carried out to explore the effect of vitamin E supplementation on various hematological and biochemical parameters in hypoxia-induced oxidative stress in albino rats. METHODS: The experiments were conducted on male albino rats by intermittently exposing them to a simulated altitude of 7,576 m (25,000 ft), daily for 6 h for 15 d at 32 +/- 2 degrees C. The control group was fed vehicle only (1% Tween 80) and the experimental group was given vitamin E (40 mg per rat x d(-1)) orally, 5 d prior to and during the period of hypoxic exposure. The variables studied include: hemoglobin, hematocrit, RBC deformability index, alpha-tocopherol level, malondialdehyde (MDA), reduced glutathione (GSH), oxidized glutathione (GSSG), lactate dehydrogenase (LDH) and protein level in blood/plasma and various tissues. RESULTS: Significant increase in hematocrit and hemoglobin and decrease in RBC deformability index was observed on exposure to hypoxia while vitamin E supplementation maintained them at the normal level. Hypoxia led to the decrease in plasma vitamin E and blood glutathione (GSH) level and two-fold increase in the plasma malondialdehyde (MDA) level. Vitamin E supplementation, on the other hand, resulted in less of an increase in MDA and increased the GSH concentration significantly. LDH activity, which was elevated on exposure to hypoxia, was arrested on vitamin E supplementation. CONCLUSION: The results indicate that vitamin E supplementation results in preventing oxidative damage due to high altitude stress.

Altitude↗
PubMed2000

Gamma surgery for hemangiopericytomas.

A retrospective analysis of a consecutive series of 12 patients with 15 intracranial hemangiopericytomas treated at the University of Virginia using Gamma surgery is presented. Clinical and radiographic follow up of 3 to 56 months is available for 10 patients with 12 tumors. There was one tumor present at the time of initial Gamma surgery in each patient. Two new tumors occurred in patients previously treated. Nine of the tumors decreased in volume and three remained stable. Four of the nine tumors that shrank later progressed at an average of 22 months after treatment. Of the tumors that decreased in volume and have not progressed, the response has been for an average of 11 months. The follow-up for two tumors that remained unchanged was 10 and 34 months (average 22 months). A third tumor was unchanged at 42 months but the patient died of new disease adjacent to the treated area in the anterior skull base. There were no complications and the quality of life following the procedure was maintained or improved in every case. Gamma surgery is effective in palliating the patients by decreasing tumor volume and delaying recurrence.

Adult↗