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Biomedical subjects

Ashok Kumar

Publications and source records attributed to Ashok Kumar.

At least 181 records · Page 10Linked to original sources
PubMed2003

Metal chelate affinity precipitation of RNA and purification of plasmid DNA.

The affinity of metal chelates for amino acids, such as histidine, is widely used in purifying proteins, most notably through six-histidine 'tails'. We have found that metal affinity interactions can also be applied to separation of single-stranded nucleic acids through interactions involving exposed purines. Here we describe a metal affinity precipitation method to resolve RNA from linear and plasmid DNA. A copper-charged copolymer of N-isopropyl acrylamide (NIPAM) and vinyl imidazole (VI) is used to purify plasmid from an alkaline lysate of E. coli. The NIPAM units confer reversible solubility on the copolymer while the imidazole chelates metal ions in a manner accessible to interaction with soluble ligands. RNA was separated from the plasmid by precipitation along with the polymer in the presence of 800 mM NaCl. Bound RNA could be recovered by elution with imidazole and separated from copolymer by a second precipitation step. RNA binding showed a strong dependence on temperature and on the type of buffer used.

Acrylamides↗
PubMed2003

Properties of Air Dried Radiation Processed Amniotic Membranes under Different Storage Conditions.

Amniotic membranes collected from the placentae of screened donors were processed, air dried and sterilized by gamma irradiation at 25 kGy. Effect of storage under different temperature and humidity conditions (10 degrees C, RH 80-90%; 10 degrees C, RH 40-50%; 40 degrees C, RH 50-60% and 40 degrees C, RH 10-20%) on the properties of the membrane were examined. Infrared (IR) spectral scanning was carried out to examine degradation or change if any in the tissue under different storage conditions. The degradation of amnion on irradiation with gamma rays or during storage after irradiation would tend to produce the relative variation in IR absorption troughs. This kind of addendum was absent in all the samples indicating no qualitative change in the material property of amnion. Water absorption and water vapour transmission rate (WVTR) of the membrane remained unchanged even after 6 months. No effect on the microbial permeability of membrane was observed during storage. The amniotic membranes were found to be impermeable to different strains of bacteria - Bacillus, Escherichia coli, Pseudomonas, Citrobacter, Flavimonas and Staphylococcus. The results indicate that amniotic membranes processed by air-drying are stable and can be stored under different environmental conditions without compromise to their clinical performance.

Journal Article↗
PubMed2003

Hilar benign biliary strictures: need for subclassification.

BACKGROUND: A uniformly accepted classification allows an accurate comparison of results and formulation of a standardized treatment plan. Suggested herein is a subclassification of Bismuth type III post-cholecystectomy benign biliary strictures (BBS). METHODS: Fifty-seven patients (41%) with Bismuth type III and eight patients (6%) with type IV BBS out of a total of 139 patients with BBS were analysed retrospectively. Strictures were subclassified as type IIIA where the confluence was healthy and type III B where the roof of the confluence was healthy and right and left ductal continuity was maintained, although the floor of the confluence was scarred. RESULTS: Of 57 patients with type III BBS, 44 were subclassified as type IIIA and 13 as type IIIB. Statistically significant differences were observed in the mean operative blood loss (317 vs 635 mL, P = 0.004; 317 vs 606 mL, P = 0.006), blood transfused (0.8 vs 2.2 units, P = 0.0007; 0.8 vs 2.0 units, P = 0.0008), and duration of surgery (3.8 vs 5.1 h, P = 0.002; 3.8 vs 5.6 h; P = 0.0004) between type IIIA and IIIB, and between type IIIA and IV strictures, respectively. There were no differences in the operative parameters between type IIIB and IV strictures. There was no difference in the overall morbidity (18% vs 15% vs 25%) and septic complications among the three groups. At a mean follow up of 36.4 months, 87%, 91% and 100% of patients had excellent/good outcome in type IIIA, IIIB and IV, respectively. CONCLUSIONS: Type III biliary strictures need to be subclassified, based on whether the floor of the confluence is healthy or scarred because it influences the degree of operative difficulty and morbidity. Type IIIB BBS behave like and should be classified with type IV strictures for uniformity of result evaluation.

Adult↗
PubMed2003

Anti-inflammatory activity of some novel alpha-amino naphthalene derivatives.

alpha-Acetylamino naphthalene (1) was reacted with different aromatic aldehydes and with primary or secondary amines to give alpha-aminonaphthylsubstitutedaryl chalkones (2-5) and alpha-(substituted aminoethyl)-amidonaphthalenes (14-25), respectively. These substituted chalkones were treated with hydrazinehydrate and hydroxylamine hydrochloride to give 1-acetyl-5-substitutedaryl-3-(alpha-aminonaphthyl)-2-pyrazolines (6-9) and alpha-(2-substitutedaryl-isoxazolin-4-yl)-aminonaphthalenes (10-13), respectively. Their chemical structures were confirmed by IR and 1H-NMR spectral data and elemental analysis. Studies of the anti-inflammatory and ulcerogenic activities and acute toxicity of these newly synthesized compounds were performed in vivo and compared with the standard drug, phenylbutazone (CAS 50-33-9). Some of these compounds showed potent anti-inflammatory activity and less ulcerogenic effects than phenylbutazone.

Animals↗
PubMed2003

Synthesis of newer indolyl/phenothiazinyl substituted 2-oxo/thiobarbituric acid derivatives as potent anticonvulsant agents.

2-Amino-5-(heteroarylmethylene)-1,3,4-oxadiazoles/thiadiazoles 7-10 were synthesized by cyclisation of 1-(heteroarylacetyl)semicarbazides/thiosemicarbazides 3-6. 5-(2'-Heteroarylmethylene-5'-aminomethylene-1',3,'4'- oxadiazol-2'-yl/thiadiazol-2'-yl)-2-oxo/thiobarbituric acids 11-18 were synthesized by condensation of compounds 7-10 at the 5th position of 2-oxo/thiobarbituric acids. The newly synthesized compounds showed anticonvulsant activity ranging from 50-90% (seizures protection). Compound 18 (5-(2'-phenothiazinylmethylene-5'-aminomethylene-1',3',4'-thiadiazol-2'- yl)-2-thiobarbituric acid) showed maximum activity being more potent than the reference drug phenytoin sodium (CAS 630-93-3).

Animals↗
PubMed2003

Newer substituted benzoxazepinyl-quinazolinones as potent antipsychotic and anticonvulsant agents.

3-Amino-[2'-substitutedaryl-3'-substitutedarylaminomethylene-2',3'- dihydro-1',5'-benzoxazepin-4'-yl]-2-methyl-quinazolin-4(3H)-ones 11-18 and 3-amino-[2'-substituted aryl-3'-substitutedaryl-azo-2',3'- dihydro-1',5'-benzoxazepin-4'-yl]-2-methyl-quinazolin-4(3H)-ones 19-26 were synthesized from 3-amino-[2'-substitutedaryl-2',3'-dihydro-1',5'- benzoxazepin-4'-yl]-2-methyl-quinazolin-4(3H)-ones 7-10 by Mannich's reaction and by diazotisation, respectively, on the 3rd position of the benzoxazepine ring of the compounds 7-10. The newly synthesized compounds showed potent antipsychotic and anticonvulsant activities.

Amphetamine↗
PubMed2003

Mechanical stress activates the nuclear factor-kappaB pathway in skeletal muscle fibers: a possible role in Duchenne muscular dystrophy.

The ex vivo effects of passive mechanical stretch on the activation of nuclear factor-kappaB (NF-kappaB) pathways in skeletal muscles from normal and mdx mouse, a model of Duchenne muscular dystrophy (DMD), were investigated. The NF-kappaB/DNA binding activity of the diaphragm muscle was increased by the application of axial mechanical stretch in a time-dependent manner. The increased activation of NF-kappaB was associated with a concomitant increase in I-kappaB (IkappaB) kinase activity and the degradation of IkappaBalpha protein. Pretreatment of the muscles with nifedipine (a Ca2+ channel blocker) and gadolinium(III) chloride (a stretch-activated channel blocker) did not alter the level of activation of NF-kappaB, ruling out involvement of Ca2+ influx through these channels. Furthermore, N-acetyl cysteine, a free radical inhibitor, blocked the mechanical stretch-induced NF-kappaB activation, suggesting the involvement of free radicals. Compared with normal diaphragm, the basal level of NF-kappaB activity was higher in muscles from mdx mice, and it was further enhanced in mechanically stretched muscles. Furthermore, activation of NF-kappaB and increased expression of inflammatory cytokines IL-1beta and tumor necrosis factor alpha in the mdx mouse precede the onset of muscular dystrophy. Our results show that mechanical stretch activates the classical NF-kappaB pathway and this pathway could be predominately active in DMD.

Acetylcysteine↗
PubMed2003

Mechanical stretch activates nuclear factor-kappaB, activator protein-1, and mitogen-activated protein kinases in lung parenchyma: implications in asthma.

We investigated the effects of mechanical stretch and induced stimulation of lung parenchyma on the activation of proinflammatory transcription factors in normal mice and in a mouse model of asthma. Mechanical stretching of lung parenchyma led to increased activation of NF-kappaB and AP-1 transcription factors. Incubation of lung parenchyma with methacholine increased the activation of NF-kappaB, which was further augmented by stretch. Activation of NF-kappaB in response to mechanical stretch was associated with the phosphorylation and degradation of IkappaBalpha and the activation of IkappaB kinase. Stretch-induced activation of NF-kappaB involves activation of stretch-activated (SA) channels and the production of free radicals. Mechanical stretch and/or treatment with methacholine resulted in an increased activation of ERK1/2 and p38 MAP kinase, and the inhibition of the activity of these kinases partially blocked the stretch-induced NF-kappaB and AP-1 activation. A greater level of NF-kappaB and ERK1/2 activity was observed in the asthmatic mice, which was further increased by mechanical stretching. The level of cyclooxygenase-2, an NF-kappaB-regulated enzyme, was also higher in lung parenchyma from asthmatic mice than in normal mice. Our data suggest that mechanical stretching of lung parenchyma activates NF-kappaB and AP-1, at least in part, through the activation of MAP kinase signaling pathways.

Animals↗
PubMed2003

Radioprotective effect of Panax ginseng on the phosphatases and lipid peroxidation level in testes of Swiss albino mice.

The Panax ginseng has been used as traditional medicine for past several years among oriental people. The present investigation has been made to assess the radioprotective efficacy of ginseng root extract in the testicular enzymes of Swiss albino mice. The Swiss albino mice were divided into different groups. (i) Ginseng treated group: The animals were administered 10 mg/kg body weight ginseng root extract i.p. (ii) Radiation treated group: The animals were exposed to 8 Gy gamma radiation at the dose rate of 1.69 Gy/min at the distance of 80 cm. (iii) Combination group: Animals were administered ginseng extract continuously for 4 d and on 4th day they were irradiated to 8 Gy gamma radiation after 30 min of extract administration. The animals from above groups were autopsied on day 1, 3, 7, 14 and 30. Biochemical estimations of acid and alkaline phosphatases and Lipid peroxidation (LPO) in testes were done. In ginseng treated group acid and alkaline phosphatases activity and LPO level did not show any significant alteration. In irradiated animals there was a significant increase in acid phosphatase activity and LPO level. However, significant decline in alkaline phosphatase activity was observed. The treatment of ginseng before irradiation causes significant decrease in acid phosphatase and LPO level and significant increase in alkaline phosphatase activity. One of the cause of radiation damage is lipid peroxidation. Due to lipid peroxidation, lysosomal membrane permeability alters and thus results in release of hydrolytic enzymes. So, an increase in acid phosphatase was noticed after radiation treatment. The alkaline phosphatase activity is associated with membrane permeability and different stages of spermatogenesis. Due to membrane damage and depletion of germ cells of testes after irradiation the enzyme activity was decreased. Ginseng markedly inhibits lipid peroxidation. It acts in indirect fashion to protect radical processes by inhibition of initiation of free radical processes and thus reduces the radiation damages in testes of Swiss albino mice.

Animals↗
PubMed2003

Radioprotection of Swiss albino mice by plant extract Mentha piperita (Linn.).

The oral administration of Mentha extract (ME) before exposure to gamma radiation was found to be effective in increasing the frequency of radiation-induced endogenous spleen colonies. A significant increase in the weight of the spleen was observed in animals of the Mentha and radiation combined group in comparison to the irradiation-alone group on day 10 of postirradiation. Furthermore, a significant increase in the body weight of animals in the Mentha and radiation combined group was observed in all the radiation doses studied. A regression analysis of survival data yielded LD50/30 as 6.48 +/- 0.07 and 11.59 +/- 0.21 Gy for the irradiation-alone and the Mentha and radiation combined group, respectively, and produced a dose reduction factor (DRF) of 1.78. Significant increases in total erythrocyte and leucocyte counts, hemoglobin concentration, and hematocrit values were observed in the animals of the Mentha and radiation combined group in comparison to the hematological values observed in the irradiation-alone group at all radiation doses studied (6, 8, and 10 Gy). A dose-dependent decrease in reduced glutathione (GSH) content and an increase in lipid peroxidation (LPO) levels were observed in control animals. However, the animals of the Mentha and radiation combined group exhibited a significant increase in GSH content and a decrease in LPO level, but the values remained below normal. A significant increase in the serum alkaline phosphatase activity was observed in the animals of the Mentha and radiation combined group during the entire period of study, and normal range was evident at 24 h (6 Gy) and day 5 (8 Gy). However, this level could not be restored even at day 30 in 10 Gy exposed animals. Measured acid phosphatase activity in the animals of the Mentha and radiation combined group was found to be significantly lower than the respective controls and attained normal value at day 5 (6 and 8 Gy) and day 20 (10 Gy).

Animals↗
PubMed2003

Polymerase chain reaction confirmed Mycoplasma pneumoniae arthritis: a case report.

We report here a case of polyarthritis caused by Mycoplasma pneumoniae in a 30 years old male who initially triggered suspicion of tuberculosis. Synovial fluid subjected to AFB smear, culture and PCR for Mycobacterium tuberculosis along with culture for aerobic and anaerobic bacteria by standard methods were negative. Synovial fluid was found to be positive by PCR for M. pneumoniae amplifying 543 bp fragment of P1 gene, however it could not be grown in culture. Specific IgG immunoglobulins to M. pneumoniae were also detected in synovial fluid as well as serum by ELISA which were further confirmed by IgG immunoblotting showing response to M. pneumoniae proteins specially immunodominant protein P1. The finding that both M. pneumoniae DNA and specific antibodies to M. pneumoniae are present in synovial fluid of the patient suggests that M. pneumoniae play an important role in arthritis. To the best of our knowledge, this is the first PCR confirmed M. pneumoniae infection in synovial fluid from a case of polyarthritis.

Adult↗
PubMed2003

Emergencies in rheumatology.

Rheumatological conditions can sometimes present as emergencies. These can occur due to the disease process or may be iatrogenic. Some of the important articular emergencies are septic arthritis, acute polyarthritis and atlanto-axial dislocation. Classical polyarteritis nodosa may present with massive gastro-intestinal bleeding, intestinal perforation or acute pancreatitis. Adult respiratory distress syndrome, bilateral pneumonitis and diffuse alveolar haemorrhage due to systemic lupus erythematosus or systemic necrotising vasculitis and ventilatory failure due to polymyositis are some of the respiratory emergencies. Scleroderma is well known to cause renal crisis which can be fatal if not diagnosed and managed promptly. Microscopic polyangiitis and Wegener's granulomatosis may cause rapidly progressive renal failure. Cerebrovascular accident, cortical vein thrombosis, seizures and acute psychosis are important neurological complications of rheumatic disease. Cardiac emergencies include tamponade, acute myocarditis and acute myocardial infarction. Vision can be threatened in Behcet's disease, temporal arteritis and seronegative spondylarthritis. Catastrophic antiphospholipid syndrome is a devastating emergency. The management of above emergencies includes critical care, immunosuppression when indicated and withdrawal of the offending drug. Anticoagulants have to be used in the management of antiphospholipid syndrome. A good understanding of these conditions is of paramount importance for proper management.

Cardiovascular Diseases↗
PubMed2003

Mentha piperita (Linn.) leaf extract provides protection against radiation induced chromosomal damage in bone marrow of mice.

Oral administration of M. piperita (1 g/kg body weight/day) before exposure to gamma radiation was found to be effective in protecting against the chromosomal damage in bone marrow of Swiss albino mice. Animals exposed to 8 Gy gamma radiation showed chromosomal aberrations in the form of chromatid breaks, chromosome breaks, centric rings, dicentrics, exchanges and acentric fragments. There was a significant increase in the frequency of aberrant cells at 6 hr after irradiation. Maximum aberrant cells were observed at 12 hr post-irradiation autopsy time. Further, the frequency of aberrant cells showed decline at late post-irradiation autopsy time. However, in the animals pretreated with Mentha extract, there was a significant decrease in the frequency of aberrant cells as compared to the irradiated control. Also significant increase in percentage of chromatid breaks, chromosome breaks, centric rings, dicentrics, exchanges, acentric fragments, total aberrations and aberrations/damaged cell was observed at 12 hr post-irradiation autopsy time in control animals, whereas Mentha pretreated irradiated animals showed a significant decrease in percentage of such aberrations. A significant decrease in GSH content and increase in LPO level was observed in control animals, whereas Mentha pretreated irradiated animals exhibited a significant increase in GSH content and decrease in LPO level but the values remained below the normal. The radioprotective effect of Mentha was also demonstrated by determining the LD(50/30) values (DRF = 1.78). The results from the present study suggest that Mentha pretreatment provides protection against radiation induced chromosomal damage in bone marrow of Swiss albino mice.

Animals↗
PubMed2003

Modulatory influence of Brassica compestris Linn var sarson on phase-II carcinogen metabolizing enzymes and glutathione levels in mice.

The present study reports the modulatory influence of 95% ethanolic extract from the seeds of B. compestris on the activity of phase-II enzymes such as glutathione S-transferase (GST), DT-diaphorase (DTD) and reduced glutathione (GSH) level in the skin, lung, kidney and forestomach of the mouse. Oral treatment with the seed extract at 800 mg/kg body wt. for 15 days significantly elevated GST in lung and forestomach and DT-diaphorase in forestomach and skin and GSH level in lung, kidney forestomach and skin. The lower dose 400 mg/kg body wt was effective only in inducing GST and DT-diaphorase activity in forestomach and reduced glutathione level in lung. The findings suggest that B. compestris seed extract may block or suppress the events associated with chemical carcinogenesis at least in part, by inducing metabolic detoxification of the carcinogen.

Administration, Oral↗
PubMed2003

Formulation and roentgenographic studies of naproxen-pectin-based matrix tablets for colon drug delivery.

A study has been carried out to assess the potential use of pectin in combination with two added hydrocolloids, i.e., hydroxy-propyl-methyl cellulose and hydroxyethyl cellulose in varied concentrations and coated with ethyl cellulose and cellulose acetate phthalate. The results of in vitro drug release showed that the matrix tablets prepared with pectin, hydroxy ethyl cellulose (20 percent) when coated with ethyl cellulose and cellulose acetate phthalate were found to be 63.0 percent, 8.4 percent, and 4.5 percent, respectively, in after eight hours during drug release study period. These results were confirmed with the results of roentgenographic studies in nine healthy human volunteers to find the shape and integrity of the dosage form. The X-ray photographs revealed that the enteric-coated tablet was visible only up to 5.5 hours and at the end of eighth hour, the photograph has not shown any presence of tablet indicating the loss of shape and size by the microflora present in the colon region. So, the results of in vitro and roentgenographic studies revealed that pectin, hydroxy ethyl cellulose (20 percent) base coated with ethyl cellulose and cellulose acetate phthalate was found to be a promising carrier for naproxen to colon.

Adult↗
PubMed2003

Susceptibility status of Japanese encephalitis vectors in Kurnool and Mehboobnagar districts of Andhra Pradesh, India.

An entomological survey in Kurnool and Mahboobnagar districts of Andhra Pradesh state, India was undertaken in January, 2002 to find out vector population of Japanese Encephalitis and their susceptibility status to different insecticides. Five Culicine species viz. of Cx. tritaeniorhynchus, Cx. vishnui, Cx. pseudovishnui, Cx. bitaeniorhynchus, Cx. gelidus were captured during the survey. Another suspected vectors Anopheles subpictus and An. hyrcanus were also prevalent in the study villages. The larval population showed a high degree of resistance to Fenthion and Temephos. The test mortality to DDT ranged between 75% and 90%. The mortality of Cx. tritaeniorhynchus, Cx vishnui and An. subpictus ranged from 85% to 95%. Cx. tritaeniorhynchus is susceptible to Deltamethrin and Cyfluthrin. Cx. vishnui showed 80 % and 85% mortality to DDT and Malathion respectively.

Animals↗
PubMed2002

Differential regulation of CD44 expression by lipopolysaccharide (LPS) and TNF-alpha in human monocytic cells: distinct involvement of c-Jun N-terminal kinase in LPS-induced CD44 expression.

Alterations in the regulation of CD44 expression play a critical role in modulating cell adhesion, migration, and inflammation. LPS, a bacterial cell wall component, regulates CD44 expression and may modulate CD44-mediated biological effects in monocytic cells during inflammation and immune responses. In this study, we show that in normal human monocytes, LPS and LPS-induced cytokines IL-10 and TNF-alpha enhance CD44 expression. To delineate the mechanism underlying LPS-induced CD44 expression, we investigated the role of the mitogen-activated protein kinases (MAPKs), p38, p42/44 extracellular signal-regulated kinase, and c-Jun N-terminal kinase (JNK) by using their specific inhibitors. We demonstrate the involvement, at least in part, of p38 MAPK in TNF-alpha-induced CD44 expression in both monocytes and promonocytic THP-1 cells. However, neither p38 nor p42/44 MAPKs were involved in IL-10-induced CD44 expression in monocytes. To further dissect the TNF-alpha and LPS-induced signaling pathways regulating CD44 expression independent of IL-10-mediated effects, we used IL-10 refractory THP-1 cells as a model system. Herein, we show that CD44 expression induced by the LPS-mediated pathway predominantly involved JNK activation. This conclusion was based on results derived by transfection of THP-1 cells with a dominant-negative mutant of stress-activated protein/extracellular signal-regulated kinase kinase 1, and by exposure of cells to JNK inhibitors dexamethasone and SP600125. All these treatments prevented CD44 induction in LPS-stimulated, but not in TNF-alpha-stimulated, THP-1 cells. Furthermore, we show that CD44 induction may involve JNK-dependent early growth response gene activation in LPS-stimulated monocytic cells. Taken together, these results suggest a predominant role of JNK in LPS-induced CD44 expression in monocytic cells.

Adult↗