Biomedical subjects

Sanjay Mishra

Publications and source records attributed to Sanjay Mishra.

11 recordsLinked to original sources

PubMed2006

Efficacy of splinting and oral steroids in the treatment of carpal tunnel syndrome: a prospective randomized clinical and electrophysiological study.

OBJECTIVE: To study the efficacy of splinting and oral steroids in the management of carpal tunnel syndrome (CTS). DESIGN: Prospective, randomized, open-label, clinical and electrophysiological study with 3-month follow-up. MATERIALS AND METHODS: Forty patients with CTS were randomly divided into splint group (N-20), wearing splint in neutral position for 4 weeks; and steroid group (N-20), who received oral prednisolone 20 mg/day for 2 weeks followed by 10 mg/day for 2 weeks. Clinical and electrophysiological evaluations were done at baseline and at 1-month and 3-month follow-up. Independent 't' test and paired 't' test were used for statistical analysis. OUTCOME MEASURES: Primary outcome measure was the symptom severity score and functional status score. Secondary outcome measures were median nerve sensory and motor distal latency and conduction velocity. RESULTS: At the end of 3 months, statistically significant improvement was seen in symptom severity score and functional status score in both groups (P<0.001). Median nerve sensory distal latency and conduction velocity also improved significantly in both the groups at 3 months. Improvement in motor distal latency was significant (P=0.001) at 3 months in steroid group, while insignificant improvement (P=0.139) was observed in splint group. On comparing the clinical and electrophysiological improvement between the two groups, except for the functional status score, there was no significant difference at 3-month follow-up. Improvement in functional status score was significantly more in steroid group (P=0.03). CONCLUSION: There was significant improvement in both groups, clinically as well as electrophysiologically, at 3 months. On comparing the efficacy of the two treatment methods, except for the functional status score, there was no significant difference between the two groups.

Administration, Oral↗

PubMed2006

Adrenoleukodystrophy manifesting as spinocerebellar degeneration.

X-linked adrenoleukodystrophy (XALD) is an inherited disorder of peroxisomal metabolism. Atypical presentations have been occasionally reported in literature. However, extrapyramidal and cerebellar manifestations are distinctly rare. We report a patient of X-linked adrenoleukodystrophy with cranial and cervical dystonia and neurological presentation resembling spinocerebellar degeneration followed by a brief review of relevant literature.

Adrenoleukodystrophy↗

PubMed2004

Quasi-static and dynamic nanoindentation studies on highly crosslinked ultra-high-molecular-weight polyethylene.

In four separate studies, the effect of three methods used to highly crosslink ultra-high-molecular-weight polyethylene (UHMWPE) (gamma irradiation, electron beam irradiation, and peroxide treatment) on the polymer's stiffness was investigated using quasi-static and dynamic nanoindentation. From the quasi-static studies, it was found that (a) the highest value of the elastic modulus, E (2240 +/- 157 MPa) was obtained from specimens prepared from direct compression molded UHMWPE crosslinked using gamma irradiation, with a dosage of 7.5 Mrad; (b) the value of E for specimens formed from direct compression molded UHMWPE was higher (1950 +/- 255 MPa) compared to results obtained from specimens formed from ram extruded UHMWPE (1583 +/- 140 MPa); and (c) the magnitude of the decrease in the value of E as a result of subjecting a highly crosslinked UHMWPE specimen to uniaxial tensile forces depends on the method used for the crosslinking. From the dynamic study, (d) it was found that the extent of the change in both the storage modulus and the loss modulus, as a result of subjecting a highly crosslinked UHMWPE specimen to uniaxial tension forces, depends on the method used for the crosslinking.

Biocompatible Materials↗

PubMed2004

The role of osteogenic index, octahedral shear stress and dilatational stress in the ossification of a fracture callus.

The exact mechanism by which mechanical stimulus regulates the healing process of a bone fracture is not understood. This has led to the development of several hypotheses that predict the pattern of differentiation of tissue during healing that may arise from characteristic fields of stress or strain at the fracture. These have so far remained unproved because data on stress fields in actual fracture tissue have been unavailable until recently. Thus the present study examines the predictive performance of the hypothesis proposed in J Orthop Res 6 (1988) 736, against measured and calculated data reported in J Biomech 33 (2000) 415, using a 2D FEM of a clinical fracture. The hypothesis was used to predict the influence of stress fields present in the Gardner et al. tissues at four temporal stages during healing. These predictions were then correlated with callus-size, rate of endochondral ossification and ossification pattern subsequently observed by Gardner et al. in the clinical fracture. Results corroborate the hypothesis that high octahedral shear stresses may increase the size of the callus during the initial phase of healing, and they also suggest that this may be true during the later stages of the fracture fixation period. However, compressive dilatational stresses were not found to inhibit endochondral ossification, as suggested by the hypothesis. Although high shear stresses were found in regions indicative of fibrous tissue as postulated by the hypothesis, this was not found to be the case for high tensile dilatational stresses. Also, contour diagrams of Osteogenic index (I) indicated only limited correlation with callus maturation and the pattern of healing. Therefore, the hypothesis was not wholly successful in predicting healing pattern.

Adult↗

PubMed2004

Research Burnout: a refined multidimensional scale.

In a prevailing academic climate where there are high expectations for faculty to publish and generate grants, the exploration of Research Burnout among higher education faculty has become increasingly important. Unfortunately, it is a topic that has not been well researched empirically. In 1997 Singh and Bush developed a unidimensional scale to measure Research Burnout. A closer inspection of the definition of this construct and the composition of its items suggests, however, that the construct may be multidimensional and analogous to Maslach's Psychological Burnout Scale. In this paper, we propose a refined, multidimensional Research Burnout scale and test its factorial validity using confirmatory factor analysis. The nomological validity of this refined scale is established by examining hypothesized relationships between Research Burnout and other constructs such as Intrinsic Motivation for doing research, Extrinsic Pressures to do research, and Knowledge Obsolescence.

Adult↗

PubMed2003

Binding and inactivation of the germ cell-specific protein phosphatase PP1gamma2 by sds22 during epididymal sperm maturation.

Testis- and sperm-specific protein phosphatase, PP1gamma2, is a key enzyme regulating sperm function. Its activity decreases during sperm maturation in the epididymis. Inhibition of PP1gamma2 leads to motility initiation and stimulation. Our laboratory is focused on identifying mechanisms responsible for the decline in PP1gamma2 activity during sperm motility initiation in the epididymis. Previously, using immuno-affinity chromatography, we showed that a mammalian homologue of yeast sds22 is bound to PP1gamma2 in motile caudal spermatozoa (Huang Z, et al. Biol Reprod 2002; 67:1936-1942). The objectives of this study were to determine: 1) stoichiometry of PP1gamma2-sds22 binding and 2) whether PP1gamma2 in immotile caput epididymal spermatozoa is bound to sds22. The enzyme from caudal and caput sperm extracts was purified by column chromatography. Immunoreactive PP1gamma2 and sds22 from both caudal and caput spermatozoa were found in the flow-through fraction of a DEAE-cellulose column. However, PP1gamma2 from caudal spermatozoa was inactive, whereas in caput spermatozoa it was active. The DEAE-cellulose flow-through fractions were next passed through a SP-sepharose column. Caudal sperm sds22 and PP1gamma2 coeluted in the gradient fraction. In contrast, caput sperm sds22 and PP1gamma2 were separated in the flow-through and gradient fractions, respectively. Further purification through a Superose 6 column showed that PP1gamma2-sds22 complex from caudal sperm was 88 kDa in size. Caput sperm sds22 and PP1gamma2 eluted at 60 kDa and 39 kDa, respectively. SDS-PAGE of these purified fractions revealed that in caudal sperm, the 88-kDa species is composed of sds22 (43 kDa) and PP1gamma2 (39 kDa), suggesting a 1:1 complex between these two proteins. PP1gamma2 bound to sds22 in this complex was inactive. Caput sperm sds22 eluting as a 60-kDa species was found to be associated with a 17-kDa protein (p17). This suggests that dissociation of sds22 from p17 or some other posttranslational modification of sds22 is required for its binding and inactivation of PP1gamma2. Studies are currently underway to determine the mechanisms responsible for development of sds22 binding to PP1gamma2 during epididymal sperm maturation.

Animals↗

PubMed2003

Effect of lacunocanalicular architecture on hydraulic conductance in bone tissue: implications for bone health and evolution.

Bone tissue health depends largely on efficient fluid and solute transport between the blood supply and cells that are the living component of the tissue. We hypothesized that the lacunocanalicular hydraulic network, which is defined by the pericellular fluid space that is common to all bone tissue, is optimized to transport fluid and solutes between the blood supply and bone cells. An analytical study was carried out to evaluate the effect of osteonal architecture, including the osteon diameter, number of annular lamellar regions, and number and length of canalicular channels, on fluid transport between the blood supply and bone cells. On the basis of this analysis, we conclude that osteon size is limited to the distance over which fluid and solutes can be transported efficiently between the blood supply and cells. This analytic model suggests that hydraulic conductivity is highest in lamellar regions closest to the Haversian canal (HC) and decreases with increasing distance from the blood supply, reaching a plateau after the fifth lamella (169 micro m radius). Furthermore, an increase in the diameter of the HC, or a decrease in the length of canaliculi, reduces the hydraulic conductivity within the lacunocanalicular network. Applying the principle of minimal expenditure of energy to this analysis, the path distance comprising five or six lamellar regions represents an effective limit for fluid and solute transport between the blood supply and cells; beyond this threshold, hydraulic resistance in the network increases and additional energy expenditure is necessary for further transportation. This suggests that transport is optimized to meet metabolic demands concomitant with a minimal expenditure of energy. This fundamental new insight into bone structure and physiology may provide a new basis of understanding for tissue engineering, bone physiology in health and disease, and evolutionary biology.

Animals↗

PubMed2003

The biomechanical environment of a bone fracture and its influence upon the morphology of healing.

The mechanism by which mechanical stimulus of reparative tissues directs the pattern of healing of a bone fracture is not understood. Several hypotheses have been developed that predict the ossification pattern during healing for a given ambient mechanical environment. These have remained unproved because of the absence of data on stress fields in the reparative tissue of real fractures. The present study examines the predictive performance of the most recent hypothesis that was proposed by Claes and Heigele (J. Biomech. 32 (1999) 255), against measured and calculated data from the clinical fracture reported by Gardner et al. (J. Biomech. 33 (2000) 415). The hypothesis was used to predict ossification from the preceding stress and strain fields present in the FEM of Gardner et al. at four temporal stages during healing. Predictions were then compared with the observed differentiation and maturation. During early healing of the interfragmentary gap region, the hypothesis correctly predicted the formation of connective tissue and fibrocartilage, and during later healing it correctly predicted the beginning of endochondral ossification. At the periphery of the periosteal callus, the hypothesis correctly predicted intramembraneous ossification during early healing, and also its thickening by endochondral ossification during later healing. However, the hypothesis incorrectly predicted intramembraneous ossification during early healing of the main periosteal callus, although in later healing it correctly predicted endochondral ossification.

Adult↗

PubMed2003

Contribution of cysteines to clathrin trimerization domain stability and mapping of light chain binding.

The three-legged or triskelion shape of clathrin is critical for the formation of polyhedral lattices around clathrin-coated vesicles. Filamentous legs radiate from a common vertex, with amino acids 1550-1615 contributed by each leg to define the trimerization domain (Liu S-H, Wong ML, Craik CS, Brodsky FM. Cell 1995; 83: 257-267). Within this amino acid stretch there are 3 cysteines at positions 1565, 1569 and 1573 which are completely conserved in higher mammals from humans to C. elegans. The cysteine-to-serine mutation at position 1573 was observed to have the largest impact on clathrin structure and self-assembly. We have also found that Cysteine 1528 located near the boundary between the proximal region and trimerization domain mediated the formation of nonproductive clathrin aggregates when bound light chain subunits were removed. However, when light chains were added back, the ability of this cysteine to form disulfide bridges between individual clathrin molecules was blocked, suggesting bound light chain interacted with Cysteine 1528 to prevent aggregation. This new information serves to map the orientation of the light chain subunit in the vicinity of the trimerization domain and supports previous models that indicate involvement of the trimerization domain in LC binding (Chen C-Y, Reese ML, Hwang PK, Ota N, Agard D, Brodsky FM. EMBO J 2002; 21: 6072-6082; Pishvaee B, Munn A, Payne GS. EMBO J 1997; 16: 2227-2239).

Amino Acid Sequence↗

PubMed2003

Influence of lamella features of UHMWPE on its physical and uniaxial tensile properties. I. Effect of sterilization method in uncrosslinked and unaged materials.

The changes in the tensile toughness (U), degree of crystallinity (%C), melting temperature (Tm), lamella thickness, and lamella alignment of uncrosslinked and unaged GUR 1150HP ultra-high-molecular-weight polyethylene specimens, following different sterilization treatments (none, gamma-irradiation in air, gamma-irradiation in a nitrogen-rich atmosphere, ethylene oxide gas, and gas plasma) were determined. For each of the properties - U, %C, and Tm - the only significant difference in the mean value was found between the set of specimens gamma-irradiated in air, on the one hand, and each of the other sets, on the other hand. It was found that lamella thickness showed little change between the groups of specimens but there was a significant difference in the lamella orientation between the set of specimens that had been gamma-irradiated in air, on the one hand, and each of the other sets, on the other. It thus appears that the changes seen in the physical and mechanical properties determined may be a reflection of the change in the polymer's lamella alignment.

Crystallization↗

PubMedDate not supplied

Aetiology and clinical profile of spontaneous pneumothorax in adults.

BACKGROUND: Limited information is available on epidemiology of spontaneous pneumothorax (SP) from India. The present study was aimed at studying aetiology and clinical profile of patients with SP. METHODS: All patients admitted at a tertiary care hospital with the diagnosis of SP between January 2001 and March 2002 were prospectively studied. Detailed demographic and clinical data were recorded. Patients were divided into two groups-primary spontaneous pneumothorax (PSP), if no underlying aetiology for pneumothorax was found, and secondary spontaneous pneumothorax (SSP), when an underlying respiratory disorder could be identified. The clinical features were compared between the two groups. RESULTS: Sixty patients (12 with PSP and 48 with SSP) were included in the study. Annual incidence of SP was calculated as 99.9 per 100,000 hospital admissions. Annual incidence figures for PSP and SSP were 20.0 and 80.0 per 100,000 hospital admissions respectively. Age distribution showed a biphasic pattern and the overall male to female ratio was 5 : 1. The most common cause of SSP was found to be pulmonary tuberculosis (41.7%). CONCLUSIONS: Pneumothorax is more common among men. In India, SSP is far more common than PSP, and the predominant underlying cause is pulmonary tuberculosis.

Adolescent↗