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Biomedical subjects

A Bhattacharya

Publications and source records attributed to A Bhattacharya.

At least 145 records · Page 8Linked to original sources
PubMed1994

Magnesium-induced structural changes in tubulin.

Exogenously added Mg2+, in the intracellular concentration range, has significant effect on the conformation of tubulin as monitored by tryptophan fluorescence. This magnesium-induced conformational change is reflected in the change of the slope and intercept of the Lehrer plot. The off-rate of colchicine from colchicine-tubulin complex is also decreased severalfold upon the addition of exogenous magnesium. The conformational change is magnesium-specific, and magnesium can only be replaced by manganese. GTP, CaCl2, and NaCl have no effect. Magnesium, however has no effect on tryptophan accessibilities of tubulin-S. Implications of these results are discussed in terms of C-terminal tail-body interaction.

Animals↗
PubMed1994

Purification and partial characterization of a heparin-binding lectin from the marine clam Anadara granosa.

The heparin-binding lectin, Anadarin MS, from the plasma of the marine clam Anadara granosa is purified through affinity chromatography on heparin-Sepharose 4B followed by gel filtration on a Sepharose 6B column. The purified lectin is a pentameric protein of native M(r) 300 kDa and is composed of identical subunits of 60 kDa. The pI value of this Ca(2+)-dependent lectin is 6.2. Anadarin MS agglutinates normal rabbit erythrocytes but not that of human. Aspartic acid, glutamic acid, histidine and glycine are the predominant amino acids. Unlike other reported heparin-binding lectins, Anadarin MS exhibits a unique and strict specificity for iduronic acid containing glycosaminoglycans. This lectin agglutinates infective promastigotes of Leishmania donovani exclusively and can therefore be used as a novel biochemical surface marker for this parasite.

Agglutination↗
PubMed1994

Evaluation of occupational knee-joint stress using liquid crystal thermography: a case study.

This paper describes a method to detect knee stress using liquid crystal thermography and presents the results of a case study in which the system was applied to two carpet installers. The method involves placing heat-sensitive sheets of film on the knees of workers at various intervals during the work day. The thermographic sheets react to variations in heat by changing colour. The measurements are taken with the worker's knee positioned in an illuminated, enclosed box. Once the patch stabilizes, the exhibited colours are recorded with an 8 mm video camera. The colour pattern, ranging from brown to blue, provides a thermal record of what is believed to be knee stress resulting from installing carpet. The thermographic records are stored in computer memory for subsequent analysis using an AT&T TARGA 16 video board. Custom software allows computation of the area of each distinct colour pattern as a percentage of total patch size. These records provide a characterization of knee response (inflammation) resulting from the biomechanical load sustained by the knee during the carpet installation task.

Journal Article↗
PubMed1994

Nucleotide sequence organisation and analysis of the nuclear ribosomal DNA circle of the protozoan parasite Entamoeba histolytica.

We have sequenced the extrachromsomal ribosomal DNA (rDNA) circle of the human protozoan parasite Entamoeba histolytica HM-1:IMSS and present here the complete sequence organisation of the 24.5-kb molecule. Each circle contains two 5.9-kb rDNA transcription units organised as inverted repeats. The regions downstream (3543 bp) and upstream (9216 bp) of the rDNAs contain various families of short tandem repeats. Some of the upstream repeats share extensive sequence homology with the downstream repeats. In addition to the rDNAs themselves, the rDNA circle appears to code for only one other transcript which is 0.7 kb in size as seen in Northern blots. From DNA sequence analysis, no open reading frame could be assigned to the transcript. Extrachromosomal rDNA circles also exist in other E. histolytica strains. Restriction enzyme maps of rDNA circles were constructed from E. histolytica strains 200:NIH, HK-9 and Rahman; and Entamoeba moshkovskii strain Laredo. Striking differences were observed in the organisation of some of them, e.g. the HK-9, Rahman and Laredo circles contained only one rDNA unit and lacked the 0.7-kb transcript sequence. The short repeat sequences upstream and downstream of rDNAs were present in HK-9 and Rahman but absent in Laredo. Circles with one rDNA unit may be derived from those with two units by homologous recombination at direct repeat sequences located upstream and downstream of the two rDNAs.

Animals↗
PubMed1994

Isolation and characterization of a species-specific multicopy DNA sequence from Entamoeba histolytica.

A genomic library of Entamoeba histolytica (pathogenic strain HM-1:IMSS) was screened to detect repetitive DNA clones other than those from the highly abundant ribosomal DNA (rDNA). One such clone (HMc) had a 2.3 kb insert which hybridized with the main genome and not the rDNA circle. Southern hybridization of E. histolytica genomic DNA, digested with EcoR I and probed with HMc, showed multiple bands. The banding pattern was identical in all axenic pathogenic strains tested. Differences, however, existed when the banding pattern of a pathogenic strain was compared with that of a non-pathogenic strain. HMc was present in about 25-30 copies per genome in strain HM-1:IMSS. Nucleotide sequence analysis of HMc revealed a partial open reading frame which hybridized with a 1.35 kb poly A+ transcript in Northern blots. The deduced amino acid sequence did not, however, show significant homology with known proteins. The HMc sequence was found only in E. histolytica as it hybridized with 5 different axenic strains of E. histolytica but did not recognize other closely related species of Entamoeba. It has thus the potential to be used as a species-specific DNA probe.

Amino Acid Sequence↗
PubMed1994

Brainstem auditory evoked response changes following electro-acupuncture therapy in chronic pain patients.

Brainstem auditory evoked responses were recorded in 17 patients with chronic pain who had been given electro-acupuncture therapy. The absolute peak latencies of waves I to V, and interpeak latencies and amplitudes of waves I and V were analysed before electro-acupuncture and compared with values obtained during electro-acupuncture and 5 min after its termination after one, five and 10 sittings. At these sittings the intensity of pain was recorded with the help of a 100 mm visual analogue scale. Each patient had 10 sittings given on alternate days. The absolute peak latencies of waves I, II, and III were delayed significantly (p < 0.05) after 5 and 10 sittings and amplitudes of wave V decreased significantly (p < 0.05) after 5 and 10 sittings. Visual analogue scores also decreased significantly (p < 0.01) during these sittings. It was established that before and after 10 sittings of electro-acupuncture, there was a significant positive correlation between visual analogue scores and the amplitude of wave V (p < 0.01). There was a negative correlation between visual analogue scores and absolute peak latencies of wave III at 1, 5 and 10 sittings, suggesting that there is a definite interaction between the electro-acupuncture neural mechanism and the generators of brainstem auditory evoked responses in the lower brainstem.

Adolescent↗
PubMed1994

Infra-orbital nerve block for relief of postoperative pain following cleft lip surgery in infants.

The study was conducted on 20 infants scheduled for cleft lip repair surgery. Ten were randomly allocated to receive bilateral infra-orbital local anaesthetic nerve blocks at the conclusion of surgery with the other 10 receiving bilateral 'sham' blocks as controls. Postoperative pain relief was assessed using a pain assessment scoring system and by monitoring arterial blood pressure, heart rate and respiratory rate. The mean pain assessment score was significantly higher (i.e. better) (p < 0.05) in the infants receiving the local anaesthetic block. There were no significant statistical or clinical differences in the physiological measurements between the two groups. The infants receiving the block required less analgesia in the postoperative period. The results suggest that infra-orbital nerve block is a simple and effective means of achieving postoperative analgesia after cleft lip repair surgery in infants.

Blood Pressure↗
PubMed1994

Recovery from pre-operative sedation with clonidine--brain stem auditory evoked response.

In a randomised double-blind study, 34 elderly patients (ASA grades 1-2) underwent elective intra-ocular surgery. Patients were allocated randomly to two groups to receive oral clonidine 300 micrograms or oral diazepam 10 mg 2 h before surgery. Facial block and retrobulbar block were given at 2 h after premedication. Anaesthetic recovery was assessed using a clinical recovery score (at 0, 30, 60 and 120 min after arrival in the recovery room) and brain stem auditory evoked potential responses (BAER) (immediately after operation and at 120 min after operation). In both the groups the clinical recovery scores decreased significantly at 30 and 60 min following recovery (p < 0.01). At 120 min this score returned to the pre-operative value in the clonidine group, but in the diazepam group there was a significant difference between the 2h value and pre-operative value (p < 0.05). In the clonidine group there was no significant rise in the interpeak latencies and absolute peak latencies of brain stem auditory evoked responses recorded immediately after operation and 120 min after operation. In the diazepam group, there was a significant rise in the interpeak latencies immediately after operation and 120 min after operation and a rise in absolute peak latencies (p < 0.05) immediately after operation. In the clonidine group there was a reduction (p < 0.05) in amplitude of wave V at immediately after operation. We conclude that clonidine 300 micrograms orally before surgery does not delay recovery.

Aged↗
PubMed1994

Subacute toxicity of fenvalerate in broiler chicks: concentration, cytotoxicity and biochemical profiles.

Subacute toxicity study of fenvalerate was carried out in broiler chicks after oral administration @ 525.6 mg/kg once daily for 28 days. The blood concentration of fenvalerate following 1 day post-administration (pd) was 39.65 +/- 2.67 micrograms/ml and maintained plateau thereafter up to day 21 pd, and then declined (18.46 +/- 1.47 micrograms/ml) on day 28 pd. Intestine contained maximum residue (7.46 +/- 1.96 micrograms/g) followed by fat (5.95 +/- 1.16 micrograms/g), brain (5.06 +/- 0.96 micrograms/g), liver (3.93 +/- 0.51 micrograms/g), kidney (3.79 +/- 0.72 micrograms/g) and heart (1.72 +/- 0.35 micrograms/g). Histopathological examinations showed focal areas of necrosis in liver, proliferation and fibrosis of bile duct, larger size of glomeruli, glomerular and tubular necrosis in treated birds. Fenvalerate significantly increased the cholesterol level in brain, GPT activity in liver and heart, GOT activity in heart, and alkaline phosphatase activity in heart and brain tissue. It significantly decreased the glycogen content in liver and heart, GOT activity in brain and acid phosphatase activity in all the tissues analyzed. It appears that comparatively fowl is resistant to fenvalerate toxicity.

Animals↗
PubMed1994

Subcutaneous infusion of ketamine and morphine for relief of postoperative pain: a double-blind comparative study.

Low dose ketamine by subcutaneous infusion (0.1 mg.kg-1.h-1) was compared in a double-blind fashion with a similar infusion of morphine (0.03 mg.kg-1.h-1) for postoperative analgesia in 60 ASA-I adults after major abdominal surgery. Pain was assessed using visual analogue scales and sedation was graded on a four-point rank drowsiness score. Cardiovascular and respiratory parameters were also recorded. Pain relief was better with the ketamine infusion than with morphine infusion (P < 0.001). Both tidal and minute volume parameters improved better with ketamine (P < 0.001); patients were more awake and alert as evidenced by the drowsiness score (P < 0.001). Nine out of 30 patients who received morphine required catheterisation for urinary retention (P < 0.05). The study revealed higher analgesic efficacy of a low dose subcutaneous infusion of ketamine with lesser sedation and fewer side effects.

Abdomen↗