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Biomedical subjects

P Mishra

Publications and source records attributed to P Mishra.

At least 37 records · Page 2Linked to original sources
PubMed2001

Identification of yacE (coaE) as the structural gene for dephosphocoenzyme A kinase in Escherichia coli K-12.

Dephosphocoenzyme A (dephospho-CoA) kinase catalyzes the final step in coenzyme A biosynthesis, the phosphorylation of the 3'-hydroxy group of the ribose sugar moiety. Wild-type dephospho-CoA kinase from Corynebacterium ammoniagenes was purified to homogeneity and subjected to N-terminal sequence analysis. A BLAST search identified a gene from Escherichia coli previously designated yacE encoding a highly homologous protein. Amplification of the gene and overexpression yielded recombinant dephospho-CoA kinase as a 22.6-kDa monomer. Enzyme assay and nuclear magnetic resonance analyses of the product demonstrated that the recombinant enzyme is indeed dephospho-CoA kinase. The activities with adenosine, AMP, and adenosine phosphosulfate were 4 to 8% of the activity with dephospho-CoA. Homologues of the E. coli dephospho-CoA kinase were identified in a diverse range of organisms.

Adenosine↗
PubMed2001

Sampling the intramyocellular triglycerides from skeletal muscle.

To determine the extent and microanatomical distribution of extramyocellular adipocytes associated with skeletal muscle, histological, biochemical, nuclear magnetic resonance proton spectroscopic and microcomputed tomography techniques were employed to analyze skeletal muscle samples from lean and obese Sprague-Dawley rats. Significant amounts of extramyocellular adipocytes were found on the exterior surface of rat gastrocnemius, soleus, and tibialis anterior muscles. The triglyceride content of these exterior adipocytes in these muscle groups was 2- to 3-fold greater than that of the respective intramyocellular triglyceride pool (P = 0.01). Thus, the exterior adipocytes associated with skeletal muscle samples are an abundant source of extramyocellular fat potentially contaminating the intramyocellular triglyceride pool if not carefully and completely removed. On the other hand, no adipocytes were found in the interfascicular space (between muscle bundles) or the intrafascicular space (between muscle fibers) in any of the three rat muscles. The feasibility of and procedures for removing extramyocellular fat by microdissection techniques to obtain pure muscle sample were also evaluated. Complete removal of the extramyocellular adipocytes from rat skeletal muscle, using microdissection with a stereo microscope, was found to be practical and effective. It is concluded that pure muscle samples free of contamination by extramyocellular fat can be obtained, but only if microdissection techniques are utilized.

Adipocytes↗
PubMed2000

Open tip rhinoplasty along with the repair of cleft lip in cleft lip and palate cases.

This paper is a report on a procedure to perform open tip rhinoplasty at the time of lip repair in unilateral and bilateral cleft lip and palate deformity. A total of 69 patients who had this operation between 1994 and 1997 have been reviewed. Conventionally there is hesitation to do radical nasal correction for the cleft lip patient because of the fear of possible growth retardation. The present technique, while it achieves excellent postoperative results constantly, does not entail any more trauma to the cartilage complex than any of the conventional closed rhinoplasty techniques. Early results obtained by this method appear to be superior to those by closed rhinoplasty techniques.

Child, Preschool↗
PubMed2000

Autosomal dominant ectrodactyly with sensorineural deafness.

Ectrodactyly or split hand/split foot malformation as it is now known, is a rare developmental disorder sometimes associated with other systemic malformations. Very few cases of congenital hearing loss coexisting with ectrodactyly have been reported world-wide. We profile one such family with the father and daughter being affected with bilateral foot ectrodactyly minor abnormalities of the 5th fingers and severe sensorineural hearing loss (SNHL). The inheritance in this family was likely to be autosomal dominant. There were no cytogenetically demonstrable structural aberrations in either case.

Adult↗
PubMed1999

Delayed Tc-99m citrate scintigraphy in the evaluation of palpable breast masses.

The aim of this study was to evaluate the potential of Tc-99m citrate as a new tumor-localizing agent in palpable breast masses. Scintimammography was performed in 43 female patients. Of these, 10 women (group A) were considered to be healthy with no palpable breast masses, and the remaining 33 patients (group B) had palpable breast masses. All patients with palpable breast masses underwent fine-needle aspiration cytology and subsequent biopsy within 2 weeks of the study. Nine patients had a primary malignant lesion of the breast, whereas 24 patients had benign disease. The patients with breast cancer underwent surgery, and subsequently a histopathologic diagnosis was made. Sensitivity, specificity, and accuracy values obtained in our study were 87%, 100%, and 90%, respectively. Scintimammograms were performed in these patients up to 24 hours. Initial uptake at 1 and 3 hours was noted in all the breast masses. However, benign masses did not show persistence of tracer uptake at 24 hours, whereas those that were malignant continued to show persistent radionuclide concentration. Thus, the uptake and outflow pattern seemed to differentiate benign breast disease from breast cancer. The study shows the potential of Tc-99m citrate for imaging and evaluating breast masses.

Adolescent↗
PubMed1999

99Tcm-citrate: a new bone imaging radiopharmaceutical.

99Tcm-citrate has been shown to incorporate irreversibly in the skeleton with a biodistribution different to that on a conventional bone scan. The aims of this study were to confirm the bone-imaging properties of 99Tcm-citrate, to identify the variabilities influencing its skeletal uptake, to compare its uptake in bone with that of 99Tcm-MDP and to assess its possible role in bone scintigraphy. Appropriate animal and human studies (n = 45) were conducted. The 3 h lesion-to-bone ratio of 99Tcm-citrate was compared with that of 99Tcm-MDP in more than 150 lesions, including osteoblastic sites (Group A), lesions undergoing treatment or healing (Group B), and degenerative or old healed lesions (Group C). The uptake ratio was classified as concordant (< 20% variation), mildly discordant (20-50% variation) or significantly discordant (> 50% variation). Animal experiments showed most bone uptake of 99Tcm-citrate when prepared at a pH of 6.0-6.5. The two radiopharmaceuticals appeared to compete for bone uptake, suggesting related but different sites of bone accumulation. The 99Tcm-citrate/99Tcm-MDP uptake ratio in Group A was concordant (mean +/- S.D. = 0.92 +/- 0.15), while Group C lesions had a significantly lower 99Tcm-citrate/99Tcm-MDP uptake ratio (0.34 +/- 0.24, P < 0.01). A comparison of Group B lesions showed wide variation in intensity and area of involvement in many lesions (uptake ratio < 0.5 or > 1.5 in 13 of 30 sites). We conclude that 99Tcm-citrate has a different site of bone localization than phosphonates, possibly in the organic matrix. Although its skeletal uptake is lower than that of 99Tcm-MDP, it may have better specificity in differentiating osteoblastic from degenerated or healed bony lesions, and therefore be useful in predicting healing of bone secondaries, fractures or osteomyelitic lesions.

Adult↗
PubMed1998

Synthesis and biological evaluation of novel 2-[substituted acetyl]-amino-5-alkyl-1,3,4-thiadiazoles [corrected].

Sixteen novel 2-substituted acetyl amino-5-alkyl-1,3,4-thiadiazole were synthesized and screened for their pharmacological activities. A few of the compounds namely 11, 12 and 16 showed anti-inflammatory activities comparable to phenylbutazone. Compound 12 also showed significant non-specific spasmolytic activity. Diuretic activity of compound 15 at a dose level of 90 mg/kg p.o. was two fold higher compared to 50 mg/kg p.o. of furosemide. Comparable diuresis was also produced by compounds 9, 10 and 16.

Animals↗
PubMed1998

Differentiation of malignant and degenerative benign bone disease using Tc-99m MDP and Tc-99m citrate scintigraphy.

The authors present a prospective analysis of Tc-99m MDP and Tc-99m citrate scintigraphy in 108 patients with known malignant or degenerative benign bone disease. Of 108 patients, 59 (group A) had malignant bone disease. The other 49 patients (group B) had degenerative benign bone disease for which the results of Tc-99m MDP scans were positive. In both groups the Tc-99m citrate scan was performed 1 week after the Tc-99m MDP scan. The Tc-99m citrate/Tc-99m MDP lesion-to-background radioisotope uptake ratio (RUR) was calculated for each lesion 3 hours after radionuclide administration. The mean RUR for the malignant lesions was 1.0 +/- 0.484; for the benign lesions, the RUR was 0.29 +/- 0.250. Static imaging was also done for 10 lesions each from the malignant and benign groups at 1, 3, and 24 hours to study the kinetics of Tc-99m citrate. Time-activity curves for malignant lesions showed that the RUR remained high for 24 hours, whereas benign lesions showed a drastic decrease at 3 and 24 hours compared with the 1-hour images. The ratio of Tc-99m citrate to Tc-99m MDP is a promising parameter to differentiate malignant from benign degenerative lesions seen as areas of increased activity on Tc-99m MDP bone scans. The sensitivity and specificity of this technique were 97.8% and 95%, respectively.

Adult↗
PubMed1996

Scintiscan demonstration of localized bowel loop inflammation. Comparison of Tc-99m dextran, Tc-99m citrate, and Tc-99m human immunoglobulin G.

A 60-year-old man with localized small bowel inflammation underwent abdominal scintigraphy with Tc-99m human polyclonal immunoglobulin G and two experimental inflammation-seeking agents, Tc-99m dextran and Tc-99m citrate. The abnormal loop was visualized in all the three studies. Additionally, the Tc-99m dextran study revealed exudation and luminal transit of the tracer suggestive of regional protein-losing enteropathy. The authors conclude that Tc-99 dextran and Tc-99 citrate are clinically suitable inflammation-seeking agents that need further evaluation, especially for locating abdominal inflammations.

Citrates↗
PubMed1996

A kit for the instant preparation of 99Tcm-citrate for tumour and inflammation scintigraphy.

A lyophilized kit has been developed to produce 99Tcm-citrate (99%) instantly when mixed with 99TcmO4-. The ingredients of the kit, citrate and stannous chloride, are in a ratio of 100:1 (w/w) and are bound to 700 MBq 99Tcm, sufficient for use in a single patient. The shelf life of the kit when kept refrigerated is at least 3 months. The blood clearance and organ distribution of 99Tcm-citrate have been studied in rabbits and mice respectively, showing its fast clearance (55% at 5 min) and low uptake by the reticulo-endothelial system and other organs. The main route of clearance is via the kidneys. Scintigraphic studies in experimental mice have demonstrated high levels of accumulation of 99Tcm-citrate in turpentine-induced abscess (target-to-non-target ratio 4.2:1) and EAT implanted tumour in mice (T/NT 5:1) 1 h after its administration. In keeping with these animal studies, low uptake of 99Tcm-citrate by normal organs and fast blood clearance have been demonstrated in human patients with infection and tumour as early as 5 min post-administration. This study documents a new kit developed for the preparation of 99Tcm-citrate suitable for the scintigraphic assessment of abscess, infection and tumour.

Abscess↗
PubMed1995

Fourier-transform infrared spectroscopic investigation of protein stability in the lyophilized form.

Upon the removal of water, proteins undergo a major, reversible rearrangement of their secondary structure, as revealed by FTIR spectroscopy. We have found herein that for recombinant human albumin (rHA) the extent of this structural change does not depend significantly either on the composition of the aqueous solution prior to lyophilization (protein concentration, pH, and the presence of excipients such as dextran or NaCl) or on the mode of dehydration (lyophilization, spray drying, or rotary evaporation), even though these factors profoundly affect rHA's solid-state stability against moisture-induced aggregation. In all cases, the alpha-helix content of rHA drops from 58% in solution to 25-35% in the dehydrated state, the beta-sheet content rises from 0 to 10-20%, and unordered structures increase from 40% to 50-60%. We have also investigated another model protein, hen egg-white lysozyme, and confirmed that it too undergoes a significant alteration of the secondary structure upon lyophilization. The extent of this structural reorganization has been found to be insensitive to the pH of the aqueous solution prior to lyophilization from pH 1.9 to 5.1, even though the thermal transition temperature (Tm) in aqueous solution over this range varies by 30 degrees C.

Dextrans↗
PubMed1994

A simplified kit for instant preparation of technetium-99m human immunoglobulin-G for imaging inflammatory foci.

A kit consisting of reduced human immunoglobulins G (hIgG), methylene diphosphonate, stannous chloride and ascorbic acid has been developed to instantly produce technetium-labelled hIgG of greater than 97% purity and suitable for inflammation foci scintigraphy in patients. The shelf life of the kit when stored at 4-7 degrees C was at least 3 months. 99mTc-hIgG prepared from the kit, when incubated at 37 degrees C for 24 h in physiological saline and human serum was found to degrade by only 7.8 and 4.3%, respectively, thereby indicating high stability of the labelled product. Competitive RIA data did not exhibit loss of immunoreactivity of the hIgG due to its reduction. Blood clearance of the radiopharmaceutical in rabbits exhibited a monophasic exponential pattern. Biodistribution in mice showed uptake by liver (4.93%), kidneys (3.07%) and intestines (2.12%) at 4 h which was reduced to 1.99, 2.18 and 1.93%, respectively at 24 h. Radiolabelled hIgG prepared from the kit was found to be quite satisfactory for inflammation scintigraphy in human patients.

Animals↗