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Biomedical subjects

A D Shah

Publications and source records attributed to A D Shah.

11 recordsLinked to original sources
PubMed2005

Correlation of radiographic and telemetric data from massive implant fixations.

One proximal femoral replacement (PFR) and two distal femoral replacements (DFR) used in tumoural limb salvage were instrumented to measure axial force in the femoral shaft and at the tip of the intramedullary stem in vivo. The prostheses were implanted in suitable subjects and regular recording sessions held over 2 years for each subject. The ratio of the tip force to the shaft force increased with time in all 3 subjects, albeit at different rates, indicating that a greater proportion of the load was being transmitted along the prosthesis stem. The aim of this study was to correlate these changes with bone remodelling observed radiographically over the same period. Radiographs were analysed using a computer-assisted method to quantify bone width, radiolucent line width and relative bone density. The analysis showed the development of radiolucent lines at the bone-cement interface and a decrease in the lateral to medial ratio of bone density near the transection site. For the PFR, the mean width of the radiolucent area alongside the proximal fifth of the stem on the lateral side increased from 0 to 0.67 mm over the 2 years. The tip to shaft ratio correlated significantly with radiolucency on the lateral side of the stem. Both the DFRs became loose within 2 years but the PFR has remained in situ for 13 years to date. The correlations found thus far suggest that it may be possible to establish relationships between load transfer (and therefore loosening in the fixation) and radiographic data, with possible application to advance warning of clinical loosening in stemmed implants.

Adult↗
PubMed2002

Quantitative analysis of actin patch movement in yeast.

To investigate the mechanism of cortical actin patch movement in yeast, we implement a method for computer tracking the motion of the patches. Digital images from fluorescence microscope movies of living cells are fed into an image-processing program, which generates two-dimensional patch coordinates in the plane of focus for each movie frame via an algorithm based on detection of rapid intensity variations. The patch coordinates in neighboring frames are connected by a minimum-distance algorithm. The method is used to analyze control cells and cells treated with the actin-depolymerizing agent latrunculin. The motion of the patches in both cases, as analyzed by mean-square patch displacements, is found to be a random walk on average, with a much lower diffusion coefficient for the latrunculin-treated cells. The mean-squared patch travel distances for all of the latrunculin-treated cells are lower than those for all of the control cells. The patches move independently of one another. We develop a quantitative criterion for the presence of directed motion, and show that numerous patches in the control cells display directed motion to a very high degree of certainty. A small number of patches in the latrunculin-treated cells display directed motion.

Actins↗
PubMed2001

A study of chromosome aneuploidy in hereditary breast cancer patients and their healthy blood relatives.

Chromosomal abnormalities that may predispose a group of individuals to develop certain neoplasms have been reported in lymphocytes. We evaluated cytogenetic abnormalities in 21 histopathologically confirmed primary breast cancer patients (BCPs), 52 healthy blood relatives (HBRs), belonging to 19 hereditary breast cancer families (HBFs) and 25 females as control. Phytohemagglutinin stimulated peripheral blood lymphocyte (PBL) cultures were used to study the chromosomal abnormalities in BCPs and their HBRs. Short term culture of the tumor tissue was also carried out in defined growth medium. Suitable metaphases (11 to 55) from tumors and a minimum of 100 metaphases from PBL were karyotyped for the cytogenetic analysis. Heterogeneous population of cells with random and nonrandom chromosomal abnormalities was noticed in tumors. In control groups 2-5% of metaphases showed numerical abnormalities, whereas this phenomenon was observed in 3-18% of metaphases in HBRs and 3-23% of metaphases in BCPs. In tumor tissue, 47.05% of BCPs showed numerical abnormalities in more than 16 metaphases. In lymphocytes, this event was observed in 33.33% of BCPs and 13.14% of HBRs. In controls 1.28%, in BCPs 52.04% (tumor) and 13.42% (lymphocytes), and in HBRs 9.03% of metaphases were found aneuploid. Statistically it was highly significant (Fisher's exact test, P<0.00001). In lymphocytes of BCPs, chromosomes 1, 6, 8, 9, 15, 17, 18, 20, and X and in HBRs, chromosomes 8, 15, 17, 18, and X were frequently involved. It can be inferred from the findings that the above mentioned chromosomes may have an important role in early stage of breast carcinogenesis in BCFs. Moreover, presence of similar abnormalities in HBR indicates inherited pattern of this genetic error among them.

Adult↗
PubMed1999

Finite strain elastodynamics of intracranial saccular aneurysms.

Various investigators suggest that intracranial saccular aneurysms are dynamically unstable, that they resonate in response to pulsatile blood flow. This hypothesis is based on linearized analyses or experiments on rubber "models", however, and there is a need for a more critical examination. Toward this end, we (a) derive a new nonlinear equation of motion for a pulsating spherical aneurysm that is surrounded by cerebral spinal fluid and whose behavior is described by a Fung-type pseudostrain-energy function that fits data on human lesions, and (b) use methods of nonlinear dynamics to examine the stability of such lesions against perturbations to both in vivo and in vitro conditions. The numerical results suggest that this sub-class of lesions is dynamically stable. Moreover, with the exception of transients associated with initial perturbations, inertial effects appear to be insignificant for fundamental forcing frequencies less than 10 Hz and hence for typical physiologic and laboratory conditions. We submit, therefore, that further study of the mechanics of saccular aneurysms should be focused on quasi-static stress analyses that investigate the roles of lesion geometry and material properties, including growth and remodeling.

Algorithms↗
PubMed1999

Mechanical behavior of a vein pouch saccular aneurysm model.

The response of an intracranial saccular aneurysm to applied loads, whether blood pressure or endovascular intervention, depends on both the geometry and material properties of the lesion. Yet, in the development of animal models of these lesions little attention has been given to the evaluation of their mechanical behavior. Our goal was to compare the multiaxial mechanical behavior of a canine vein pouch model to published data on veins and human aneurysms. Nine vein pouches were created surgically in six mongrel dogs by anastomosing a 2 cm segment of the external jugular vein to the common carotid artery in an end-to-side fashion. The lesions were harvested one week post-surgery and subjected to cyclic inflation tests using a custom system. Pressure-regional strain data revealed that vein pouch aneurysms are very extensible for pressures up to 30 mmHg, especially in the axial direction, but stiff thereafter. None of the lesions ruptured in vivo or during inflation tests. Based on these data, we conclude that the overall behavior of canine vein pouch lesions, at one week post-surgery, did not mimic well that of human aneurysms. Thus, there is a need to pursue modifications or other models for the purposes of clinically relevant studies of lesion growth, rupture, and treatment.

Animals↗
PubMed1994

Breast-feeding practices in Schedule Caste communities in Haryana state.

A study was conducted to assess exclusive breast-feeding, continued breast-feeding, bottle-feeding, predominant breast-feeding, timely complementary feeding and other breast-feeding practices in 818 children in the age group of 0-3 years belonging to the Schedule Caste communities of Haryana. The exclusive breast-feeding rate was 0.15 and the predominant breast-feeding rate 0.75 in children < 4 months. Timely complementary feeding rate was 0.42. The continued breast-feeding rate at 1 year and 2 years was 0.84 and 0.58, respectively. The bottle-feeding rate, ever breast-fed rate, timely first-suckling rate and exclusive breast-feeding rate by mother were 0.09, 1.0, 0.0 and 0.15, respectively. The median duration of breast-feeding was 16 months.

Bottle Feeding↗
PubMedDate not supplied

Usefulness of cytogenetics in leukemias.

Present study consists of cytogenetic evaluation in 141 cases referred to our centre for various leukemias. This includes 110 cases of CML, 10 of ALL, 16 of AML (M3), 2 of AML(M2), 2 of MDS and 1 of CMML. The conventional cytogenetic study was carried out in all the cases using G Banding technique. Of the 141 patients studied, 17 patients showed secondary chromosomal alterations along with primary chromosomal alterations. In two patients of CML with secondary chromosomal alteration t(4:9:22), molecular cytogenetic technique (FISH) has been carried out which has confirmed the primary observations revealed by the conventional cytogenetic technique. Other secondary alterations were numerous and would have been missed if only FISH or PCR technique would have been used for diagnosis. We observed from our study that advanced molecular techniques like FISH and PCR cannot replace the conventional cytogenetic study but are useful as supportive and confirmative diagnostic tools.

Acute Disease↗
PubMedDate not supplied

Cytogenetics and fluorescence in-situ hybridization in detection of hematological malignancies.

BACKGROUND: The technique of Fluorescence In-Situ Hybridization (FISH), a hybrid of cytogenetics and molecular biology has increased the resolution and application of cytogenetics in various neoplastic processes. In various types of leukemias, primary investigation by conventional cytogenetic [CC] technique followed by FISH has increased our understanding of the abnormal clonal formation involving different gene region. AIMS: Present study is aimed to use different kinds of in-house FISH probes in various hematological malignancies and its correlation with conventional cytogenetic finding. MATERIAL AND METHODS: Cytogenetic study was carried out in 360 patients either from peripheral blood or from bone marrow cells suspected for various types of leukemias. Four of 360 cases were further selected for FISH study by using different types of in-house probes, such as BAC [Bacterial Artificial Chromosome], PAC [Phague Artificial Chromosome], alphoid, PCP [Partial Chromosome Paint] and WCP [Whole Chromosome paint]. RESULTS: The results confirmed breakpoints of inversion 16 and del 16 in case 2 and 3 respectively. Whereas, case 1 did not confirm the cytogenetic findings of t(15;17) by PML/RARa fusion signals as multiple cell lines were involved in the patients. PCP and WCP were helpful in the identification of the marker chromosome in case 1. Telomeric and centromeric probes confirmed the cytogenetic findings of t(5;7) in case 4. CONCLUSION: We observe from this study that, in addition to the conventional cytogenetic study, FISH study provide further confirmation of chromosomal rearrangements. This facilitates our understanding of the neoplastic process more precisely for the better prognostication of the patient.

Bone Marrow Cells↗