Biomedical subjects

K Bose

Publications and source records attributed to K Bose.

At least 19 recordsLinked to original sources

PubMed2000

Structural examination of the nickel site in chromatium vinosum hydrogenase: redox state oscillations and structural changes accompanying reductive activation and CO binding.

An X-ray absorption spectroscopic study of structural changes occurring at the Ni site of Chromatium vinosum hydrogenase during reductive activation, CO binding, and photolysis is presented. Structural details of the Ni sites for the ready silent intermediate state, SI(r), and the carbon monoxide complex, SI-CO, are presented for the first time in any hydrogenase. Analysis of nickel K-edge energy shifts in redox-related samples reveals that reductive activation is accompanied by an oscillation in the electron density of the Ni site involving formally Ni(III) and Ni(II), where all the EPR-active states (forms A, B, and C) are formally Ni(III), and the EPR-silent states are formally Ni(II). Analysis of XANES shows that the Ni site undergoes changes in the coordination number and geometry that are consistent with five-coordinate Ni sites in forms A, B, and SI(u); distorted four-coordinate sites in SI(r) and R; and a six-coordinate Ni site in form C. EXAFS analysis reveals that the loss of a short Ni-O bond accounts for the change in coordination number from five to four that accompanies formation of SI(r). A shortening of the Ni-Fe distance from 2.85(5) A in form B to 2.60(5) A also occurs at the SI level and is thus associated with the loss of the bridging O-donor ligand in the active site. Multiple-scattering analysis of the EXAFS data for the SI-CO complex reveals the presence of Ni-CO ligation, where the CO is bound in a linear fashion appropriate for a terminal ligand. The putative role of form C in binding H(2) or H(-) was examined by comparing the XAS data from form C with that of its photoproduct, form L. The data rule out the suggestion that the increase in charge density on the NiFe active site that accompanies the photoprocess results in a two-electron reduction of the Ni site [Ni(III) --> Ni(I)] [Happe, R. P., Roseboom, W., and Albracht, S. P. J. (1999) Eur. J. Biochem. 259, 602-608]; only subtle structural differences between the Ni sites were observed.

Carbon Monoxide↗

PubMed2000

Comparison of anthropometric characteristics between normotensive and hypertensive individuals among a population of Bengalee Hindu elderly men in Calcutta, India.

A comparative investigation of 99 normotensive and 111 hypertensive Bengalee Hindu elderly men (aged 55 years and above) of Kalighat, South Calcutta, India, was undertaken to study differences in levels of adiposity, body fat distribution and body composition between these two groups. Results revealed that there were significant differences between normotensive (NT) and hypertensive (HT) subjects in the mean values for weight (p < 0.05), body mass index (BMI, p < 0.01); waist (p < 0.001) and hip circumferences (p < 0.05); waist-hip ratio (WHR, p < 0.001), conicity index (CI, p < 0.01) and fat free mass (FFM, p < 0.001). Percentile distributions for all these variables and indices showed consistently higher values among the HT patients as compared with NT subjects. However, the frequency of obesity (BMI > or = 25) was similar (NT = 6.1%, HT = 11.7%) in both groups. Thus, these results indicated that there existed significant differences in central adiposity and FFM between NT and HT subjects although their level of obesity was similar. Hypertensive individuals have significantly enhanced levels of central body fat distribution.

Aged↗

PubMed1999

Examination of the nickel site structure and reaction mechanism in Streptomyces seoulensis superoxide dismutase.

Superoxide dismutases are metalloenzymes involved in protecting cells from oxidative damage arising from superoxide radical or reactive oxygen species produced from superoxide. Examples of enzymes containing Cu, Mn, and Fe as the redox-active metal have been characterized. Recently, a SOD containing one Ni atom per subunit was reported. The amino acid sequence of the NiSOD deduced from the nucleotide sequence of the structural gene sodN from Streptomyces seoulensis is reported and has no homology with other SODs. X-ray absorption spectroscopic studies coupled with EPR of the Ni center show that the Ni in the oxidized (as isolated) enzyme is in a five-coordinate site composed of three S-donor ligands, one N-donor, and one other O- or N-donor. This unique coordination environment is modified by the loss of one N- (or O-) donor ligand in the dithionite-reduced enzyme. The NiSOD activity was determined by pulse radiolysis, and a value of kcat = 1.3 x 10(9) M-1 s-1 per Ni was obtained. The rate is pH sensitive and drops off rapidly above pH 8. The results characterize a novel class of metal center active in catalyzing the redox chemistry of superoxide and, when placed in context with other nickel enzymes, suggest that thiolate ligation is a prerequisite for redox-active nickel sites in metalloenzymes.

Amino Acid Sequence↗

PubMed1999

The efficacy and safety of eperisone in patients with cervical spondylosis: results of a randomized, double-blind, placebo-controlled trial.

A randomized, double-blind, clinical trial was undertaken to assess the activity of eperisone hydrochloride (50 mg t.i.d.), a commonly used muscle relaxant, as a treatment for cervical spondylosis in 157 patients. The results showed a clear benefit of eperisone treatment with regard to pain in the nuchal region, back pain, pain in arms and shoulders, stiffness and other symptoms of cervical spondylosis, while the tolerability of the treatment was optimal.

Adult↗

PubMed1997

Evaluation of a simple and low-cost external fixator.

Simple external fixation is becoming ever more popular for the treatment of fractures. Current commercially available external fixation devices are complex and expensive, affecting management of injuries in less developed countries. In this study, a new simple and low-cost external fixator called the AG (Alinoor-Goh) fixator, is evaluated biomechanically by direct comparison with a commercially available fixator device (AO). Four modes of loading were applied to each of the fixators: axial compression, anterior-posterior bending, medial-lateral bending, and torsion. The loads were applied directly onto a fractured-bone model made of perspex, which was immobilized by the fixator through six Schanz pins. From this, stiffness values were obtained by plotting load versus displacement. The results from the mechanical testing indicated that in axial compression the AG fixator stiffness was 55.7 +/- 0.197 N/mm (AO fixator was 57.7 +/- 0.186 N/mm); for anterior-posterior bending it was 56.8 +/- 0.153 N/mm (57.4 +/- 0.134 N/mm); for medial-lateral bending it was 11.4 +/- 0.036 N/mm (11.6 +/- 0.053 N/mm); and for torsion it was 1.16 +/- 0.002 N.mm/degree (1.16+/- 0.003 N.mm/degree). No significant difference was found in the stiffness of AG and AO fixators, under all modes of loading. A further comparison in terms of overall design, versatility in application and cost shows the AG fixator to be a viable, inexpensive option for the treatment of long-bone fractures.

Costs and Cost Analysis↗

PubMed1997

Ipsilateral knee ligament injuries and open tibial diaphyseal fractures: incidence and nature of knee ligament injuries sustained.

Fifty patients with isolated open tibial shaft fractures were reviewed to determine the incidence and type of knee ligament injuries sustained. Eighteen patients (36 per cent) had at least one ligament injury in the ipsilateral knee; eight had multiple ligament injuries. Only four patients (22 per cent) were diagnosed as having a ligament injury at the time of initial management and the remaining 14 patients were diagnosed at the time of review for this study. There is a high incidence of ipsilateral knee ligament injuries in open tibial shaft fractures; the knee should be thoroughly examined at the time of initial fracture management.

Adult↗

PubMed1997

Periprosthetic bone remodelling after cementless total hip replacement. A prospective comparison of two different implant designs.

In a prospective study of 14 patients undergoing total hip replacement we have used dual-energy X-ray absorptiometry (DEXA) to investigate remodelling of the bone around two different designs of cementless femoral prosthesis. The bone mineral density (BMD) was measured at 12-weekly intervals for a year. Eight patients (group A) had a stiff, collarless implant and six (group B) a flexible isoelastic implant. Patients in group A showed a decrease in BMD from 14 weeks after operation. By 12 months, the mean loss in BMD was 27%, both medially and laterally to the proximal part of the implant. Those in group B showed an overall increase in BMD which reached a mean of 12.6% on the lateral side of the distal portion of the implant. Our results support the current concepts of the effects of stem stiffness and flexibility on periprosthetic remodelling.

Bone Density↗

PubMed1996

Generalised obesity and regional adiposity in adult white and migrant Muslim males from Pakistan in Peterborough.

A comparative study was made of generalised obesity (body mass index; BMI) and the regional distribution of adiposity (measured as circumferences and circumference ratios) in adult White and migrant Muslim males from Pakistan in Peterborough. No significant difference in the prevalence of obesity as measured by the BMI was observed between Whites and Pakistani migrants. Although the mean BMI values were similar in both groups, they had distinctly different body fat patterning. Whites had significantly more upper body, central body and lower body adiposity compared with Pakistani migrants. They also had significantly more total fat as well as upper body:lower body, upper body:central body, and upper body: total fat indices. Within the central body, Whites had significantly more adiposity in the waist region relative to abdomen region (Waist:Abdomen ratio). However, Pakistani migrants had significantly more abdominal adiposity relative to total adiposity (Abdomen:Sum of All Circumferences ratio) than Whites. These preliminary results clearly indicate that there is a tendency for accumulation of adiposity in the abdominal region in Asian men of Pakistani origin compared with White men irrespective of the level of generalised adiposity. The health implications of body fat patterning on non-insulin-dependent diabetes mellitus (NIDDM) and coronary heart disease (CHD) are well-known. The pattern of fat distribution observed in migrant Pakistani males in this study may exist in other migrant groups originating from the Indian sub-continent and could be one of the risk factors predisposing migrant Asians (persons originating from the Indian sub-continent) in Britain to develop NIDDM and CHD irrespective of their generalised (BMI) obesity. Future epidemiological studies should lay more emphasis on morphological fat patterning instead of BMI in Asian migrants in Britain.

Adipose Tissue↗

PubMed1996

Osteoid osteoma in a three-year-old child--a case report.

Osteoid osteoma is an uncommon tumour in the very young. We present a case of osteoid osteoma in a three-year-old boy, who was treated as a case of sclerosing osteomyelitis of the femur. Because of persistent pain and lack of response to treatment, further radiological investigation confirmed the diagnosis to be that of an osteoid osteoma.

Age of Onset↗

PubMed1996

Pattern of fall and bone mineral density measurement in hip fractures.

The objectives of this study were to determine the pattern of fall and the bone mineral density distribution in hip fracture patients. The study was carried out on 260 patients (204 females and 56 males) with hip fractures over a period of three years (i.e. 1991 to 1993). The patients were all above 50 years old and the average age was 77.7 years for women and 76.8 years for men. Information relating to their falls and subsequent hip fractures were collected. Bone mineral density of the contralateral intact femoral neck was measured using dual energy X-ray absorptiometry (Model XR26, Norland Corporation, USA). Bone mineral density in the patients with hip fracture (mean value 0.55 g/cm2) was significantly lower than the fracture threshold value of 0.64 g/cm2. Falls which would result in direct impact on the hip such as sideways, backwards and straight down formed 95.6% of the cohort. Forty-six (17.7%) of the patients fell from a seated or lying position and their bone mineral density were significantly lower (i.e. 0.45 g/cm2). Two hundred and twenty-three (85.7%) of the patients fell on hard surfaces such as ceramic, marble and concrete. Two hundred and twelve (81.5%) of the falls occurred indoors and 153 (58.8%) while walking. Low bone mineral density and falls are important risk factors in hip fracture in the elderly population. Patients with low bone mineral density can sustain a hip fracture from mild trauma such as falling from a seated or lying position. It is therefore necessary to monitor bone mineral density values as well as to prevent or minimise the risk of falling.

Absorptiometry, Photon↗

PubMed1996

Thermostable alpha-amylase production using Bacillus licheniformis NRRL B14368.

Maximum amount of extracellular alpha-amylase of B. licheniformis NRRL B14368 was obtained at the stationary phase. Highest yield of alpha-amylase was achieved with high level of crude protein and low carbohydrate level. There was a catabolite repression in the organism. Protease was produced concurrently with alpha-amylase. It was also observed that soyabean acts as an inhibitor of the protease. Optimum pH and temperature of alpha-amylase were 5-7 and 76 degrees C respectively. It was also observed that alpha-amylase production was a non-growth associated product. Maltose was an excellent inducer for alpha-amylase production. Ca2+ (0.01 M) increased the thermostability of the enzyme. Alpha-amylase purification studies were carried out by using isopropanol, acetone, ammonium sulphate solution, ion exchange chromatography. Acetone was found most suitable for the separation of alpha-amylase. Protein recovery and relative enzyme activity (as compared to that of the maximum activity of the crude enzyme) were 30.77% and 3.03 respectively.

Bacillus↗

PubMed1995

Effect of decalcification on bone mineral content and bending strength of feline femur.

The relationships between bone mineral content (BMC), bone calcium, and bone strength were studied in fractionally demineralized feline femurs. In 44 pairs of cat femurs, the right bones were decalcified in ethylene diaminetetra acetic acid (EDTA) to 20%, 40%, 60%, 80%, and 100% of the mineral content of the intact left bone (= control). The bones were then loaded to failure, and maximum strength values were recorded. The data were then used to calculate the percentage strength of the right relative to the left femurs. A correlation coefficient (r) of 0.970 was found between the percentage decalcification and percentage bending strength. A direct relationship (r = 0.876) was also observed between the total calcium extracted and total loss in BMC. The EDTA solutions were spot checked for protein content to determine if the organic matrices had been altered by demineralization. Protein was never detected. Nor did the demineralized tissues display histologic evidence of gross microscopic damage. This study has shown that in cat femurs, 20% decalcification led to about 35% loss in bending strength, and 60% decalcification caused 75% loss in strength. These values are significant as they highlight the importance of calcium to the strength of osteopenic bone.

Animals↗

PubMed1995

Effect of femoral rotation on bone mineral density measurements with dual energy X-ray absorptiometry.

Precision in femoral neck scans with dual energy X-ray absorptiometry (DXA) is affected by variability in positioning and subsequent repositioning of the femur for repeated scans. To study the in vitro effect of femoral rotation on the bone mineral density (BMD), four fresh-frozen cadaveric femurs were fixed in a specially designed jig which allows for rotation of the femurs. BMD measurements of the femurs were done in neutral position (0 degrees) i.e., with the femoral neck axis parallel to the surface of the couch and at 15 degrees, 30 degrees, and 45 degrees of internal and external rotation. In vivo precision of the femoral neck scan was determined in five normal male subjects. The scans were first done with the legs positioned using the manufacturer's foot block. Five scans were performed, with repositioning, on the left hip of each subject. The procedure was then repeated with the legs positioned using a custom-designed positioning jig to minimize the rotation of the hips during a scan. In the in vitro study, the femoral neck BMD value was minimum at neutral position (0 degrees) and increased when the femur was rotated internally or externally. In vivo precision error of the femoral neck scan was reduced by almost 50% with the use of the positioning jig when compared with the manufacturer's foot block. Femoral rotation was shown to have a significant effect on BMD measurements, and proper positioning of the femur during a scan can improve precision significantly.

Absorptiometry, Photon↗

PubMed1995

Cold extrusion deformation of UHMWPE in total knee replacement prostheses.

The use of metal-backed tibial plates in total knee replacement prostheses can result in the flow of ultra-high molecular weight polyethylene (UHMWPE) from the tibial insert into a cavity on the metal tray surface. A study of the relationship between the thickness of UHMWPE inserts and the amount of cold extrusion is reported here. An attempt was made to correlate the occurrence of cold extrusion with computer-aided analysis. UHMWPE samples of varying thickness, from 3 mm to 10 mm, were placed over cobalt-chrome (Co-Cr) discs. The Co-Cr discs had a 5 mm diameter hole placed centrally to simulate a tibial tray cavity. A cyclic load was applied at 20 Hz through a Co-Cr spherical indentor for a million cycles. The application of cyclic loading on UHMWPE samples resulted in cold-extrusion values comparable to those reported for retrieval analysis studies. Results after fatigue loading show that the samples do not suffer any gross surface damage. A shiny depression was visible at the load application site and the surface roughness value was decreased. The amount of cold extrusion increased with decreasing UHMWPE sample thickness. From the results, a minimum UHMWPE thickness of 12 mm is required if cold extrusion of UHMWPE is to be eliminated.

Biocompatible Materials↗

PubMed1995

A biomechanical model to determine lumbosacral loads during single stance phase in normal gait.

A dynamic biomechanical model to determine loads (joint forces) attained at the lumbosacral joint-centre during the stance phase of normal level walking was developed. The biomechanical model was based on rigid free body-segments; namely, the foot, shank, thigh, pelvis and head, arms and trunk (HAT) segments. In this biomechanical model, the forces and moments acting on the lumbar spine are derived from body-segment mass and movements of the trunk. These external forces and their moments must be equilibrated by internal forces, that is, contributions from the erector spinae or rectus abdominus muscle group, and abdominal pressures from within the trunk together with spine forces. Three-dimensional co-ordinate and ground-reaction force data were captured from five healthy young male subjects performing normal level walking in the motion analysis laboratory of the Department of Orthopaedic Surgery, National University of Singapore. These data were captured using the VICON motion analysis system. Both of these data sets were pre-processed, and together with relevant anthropometric parameters and physical measurements of the subject, were passed into the biomechanical model to compute the resultant loads at the lumbosacral joint-centre. The results of this study showed that the peak resultant loads at the lumbosacral joint-centre were between 1.45 and 2.07 times body-weight.

Adult↗

PubMed1995

A comparative study of generalised obesity and anatomical distribution of subcutaneous fat in adult white and Pakistani migrant males in Peterborough.

Obesity can be defined in two main ways--generalised obesity (measured as Body Mass Index (BMI)) and anatomical distribution of adiposity. A comparative study of generalised obesity (body mass index) and the anatomical distribution of subcutaneous fat in adult White and Pakistani migrant males was carried out in Peterborough. No significant difference in the prevalence of obesity as measured by the BMI was observed between Whites and Pakistani migrants. The mean BMI values were similar in both ethnic groups. However, Pakistanis had significantly more truncal fat compared with Whites whereas the latter group had more upper extremity fat compared with the former. No significant difference was observed in the amount of fat deposited on the lower extremities between the two ethnic groups. The Pakistanis also had significantly more total (sum of all skinfolds) subcutaneous fat compared with Whites. These preliminary results clearly indicate that there is a tendency for accumulation of truncal adiposity in Asians of Pakistani origin compared with Whites irrespective of the level of generalised (BMI) obesity. The health implications of body fat patterning on non-insulin-dependent diabetes mellitus (NIDDM) and coronary heart disease (CHD) are well known. It is possible that the pattern of fat distribution observed in migrant Pakistani males in this study exists in other migrant groups originating from the Indian subcontinent. This pronounced truncal distribution of body fat could be one of the risk factors predisposing migrant Asians in the UK to develop NIDDM and CHD irrespective of their BMI. Future epidemiological studies should lay more emphasis on morphological fat patterning rather than BMI in Asian migrants in the UK.

Adipose Tissue↗

PubMed1995

Biomechanical study on tibialis posterior tendon transfers.

Two methods are used to route the tibialis posterior tendon anteriorly to achieve dorsiflexion: (1) around the medial side of the tibia, or the subcutaneous route; and (2) through the interosseous membrane, or the interosseous route. This study determined the effect of site of tendon insertion on ankle and foot motions and compared the efficacy of both routes. Eleven fresh normal cadaveric legs were used. The detached tibialis posterior tendon was transferred anteriorly through the interosseous membrane and anchored to the first cuneiform along the first metatarsal axis by a barbed staple. The specimen was mounted on a mechanical testing machine. Tension was applied to the tendon and ankle and foot motions were measured. The experimental procedure was repeated with tendon insertion along the second metatarsal axis and serially through to the fifth metatarsal axis. The entire experiment was repeated using the subcutaneous route. The interosseous route was more effective in achieving maximum dorsiflexion with minimal pronation. Shifting the insertion medially caused supination, whereas a more lateral insertion caused pronation.

Ankle Joint↗

PubMed1995

A cadaver study of the function of the oblique part of vastus medialis.

Six normal cadaver lower limbs were mounted on a specially designed loading apparatus. Wires were used to simulate the five muscle bellies of the quadriceps, the ratio of their tensions having been determined from that of the anatomical cross-sectional areas of the muscles. A three-camera system was used to track the patella during knee movements from flexion to extension. The patellofemoral contact area was determined by pressure-sensitive film. The limb was loaded with and without tension on the wire which simulated the oblique part of the vastus medialis (VMO). Absence of VMO tension caused the patella to displace laterally (4.2 mm) and increased the load on the lateral patellar facet throughout the range of knee motion. When the tension on the wire simulating vastus lateralis was reduced by 40% to simulate the effect of a lateral release procedure, the abnormal kinematics caused by the absent VMO returned to normal.

Biomechanical Phenomena↗