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Biomedical subjects

B Shah

Publications and source records attributed to B Shah.

At least 19 recordsLinked to original sources
PubMed1996

Contraction patterns of intrinsic laryngeal muscles induced by orderly recruitment in the canine.

The specific performance of intrinsic laryngeal muscles has been difficult to evaluate, especially in living subjects. To reproduce natural contractions, we artificially induced orderly recruitment of their innervating axons according to the size principle. In 5 dogs, both recurrent laryngeal nerves (RLNs) were stimulated with 50 through 10 Hz, 300 to 1000 microA currents while 600 Hz, 1000 to 0 microA decreasing blocking currents were administered. Surface electromyography electrodes placed on the thyroarytenoid, posterior cricoarytenoid, and lateral cricoarytenoid muscles were used to determine the amplitudes (in mA) of compound muscle action potentials. There was a highly statistically significant difference (P<.004) between the thyroarytenoideus which had the fastest rate of recruitment (8.38%), and posterior cricoarytenoideus, which had the slowest (4.81%). There was an intermediate recruitment rate (6.72%) of the lateral cricoarytenoideus, a divergence attributed to a more equal distribution in fast and slow types of myofibers and a smaller sample. We submit that RLN axons can be recruited in an orderly manner according to their sizes and that the rates are unique to the muscle classes they innervate. The parameters defining these contraction patterns may offer key information for laryngeal pacing.

Animals↗
PubMed1996

North American blastomycosis: the importance of a differential diagnosis.

Diseases from the major pathophysiological subgroups, including inflammatory, infectious, neoplastic, autoimmune, and metabolic disorders, can present in a very similar clinical manner. The importance of generating a broad differential diagnosis is supported by a case in which an 80-year-old white man presented with a verrucous plaque on the tip of his nose. The appropriate differential diagnosis for such a lesion as well as an overview of the disease diagnosed, North American blastomycosis, is presented.

Aged↗
PubMed1995

Isolated pulmonary mucormycosis in an apparently normal host: a case report.

Mucormycosis is a rare fungal disease commonly affecting individuals with diabetes mellitus, hematological malignancy, and immune deficiency. Isolated pulmonary mucormycosis is extremely rare. This article reports a case of isolated pulmonary mucormycosis that presented as a solitary cavity infiltrate in a patient with no underlying risk factors.

Aged↗
PubMed1994

Extrusion transplantation of Schwann cells into the adult rat thalamus induces directional host axon growth.

In a previous study we found that Schwann cells microtransplanted into the central nervous system rapidly dispersed from the transplantation site and became intimately associated with host grey and white matter. We have now investigated whether this migratory behavior of the donor Schwann cells is compatible with the production of stable, continuous anatomical cell tracks and whether such tracks can induce directional host axon growth. During the gradual withdrawal of a micropipette, highly purified suspensions of cultured adult peripheral nerve Schwann cells were continuously extruded to form a vertical column of cells extending for up to 4 mm through the thalamus and across the choroid fissure into the hippocampus of adult rat hosts. The donor Schwann cells were identified by immunohistochemistry for low-affinity nerve growth factor receptor, vimentin, and Rat 401. Although donor Schwann cells migrated into the host tissues, a large number remained along the axis of the injection track to form a column which was maintained for up to 3 weeks. From 4 days, increasing numbers of parallel, unbranching host RT97-positive axons entered the Schwann cell column in alignment with the long axis of the Schwann cells in the vertical tracks. The axons did not fasciculate directly with each other, but mingled diffusely with the Schwann cells. The Schwann cell tracks were able to convey host axons out of the dorsal thalamus, across the extracellular space of the choroid fissure, and into the ventral hippocampus. Thus, Schwann cells, transplanted in the form of elongated tracks, can establish bridges across boundary membranes in the brain and carry substantial numbers of nerve fibers from one area to another.

Animals↗
PubMed1994

Maternal immunity to measles and infant immunity at less than twelve months of age relative to maternal place of birth.

Sera from infants aged 5 to 11 months and from their mothers were used to investigate the level and duration of transplacentally derived measles antibody. The infants of foreign-born, inner-city mothers were more likely to have measles antibody and were less likely to get measles. Infants of foreign-born mothers, because they are less likely to respond to measles vaccine, may require different vaccine strategies than infants of mothers born in the United States.

Antibodies, Viral↗
PubMed1994

Ferromagnetic high-permeability alloy alone can provide sufficient low-frequency and eddy-current shieldings for biomagnetic measurements.

A low cost, two-shell ferromagnetic shielded room large enough for a person to enter and prepare experiments was constructed for biomagnetic measurements. No aluminium or copper shell was used for eddy-current shielding. A high-permeability nickel-iron-molybdenum alloy (1.57 mm thick) was used for both ferromagnetic and eddy-current shieldings. The shielding factor was 60 dB at dc and 40 dB between 0.1 Hz and about 3 Hz. The eddy-current shielding due to the alloy alone provided a shielding factor of 55 dB at 30 Hz and 66 dB at 60 Hz. The shielding factor was sufficiently high in all the frequency range for biomagnetic measurements with a first-order superconducting gradiometer.

Alloys↗
PubMed1994

Matrix-assisted laser desorption mass spectrometric analysis of a pegylated recombinant protein.

Matrix-assisted laser desorption ionization mass spectrometry (MALDI) has been investigated as a technique for the characterization of recombinant stem cell factor that had been covalently modified with polyethylene glycol (PEG) chains. The attachment of PEG chains produces a heterogeneous mixture of protein species that differ by 6000 Da. These differences in molecular weight could be readily determined by MALDI. The potential of MALDI as a general strategy for characterizing PEG-modified proteins is discussed.

Biotechnology↗
PubMed1993

Monoclonal antibody G10 which recognises microtubule-associated protein 1x identifies growing axons of neurons microtransplanted into adult rat hippocampus.

Monoclonal antibody G10 recognises an epitope on microtubule-associated protein 1x, a developmentally regulated cytoskeletal protein expressed in immature axons of the central and peripheral nervous systems. Here we report that G10 can be used to identify the axonal projections of syngeneic embryonic (E14-E15) hippocampal cells microtransplanted by a minimally traumatic technique into intact adult host hippocampus.

Animals↗
PubMed1993

Radical cystectomy for invasive squamous cell bladder cancer in a renal transplant patient.

A rare case of invasive squamous cell carcinoma of the urinary bladder developing 5 years after cadaveric renal transplant is described. The technical precautions to be taken while performing a radical cystectomy in such a situation is highlighted. This patient required chemotherapy in the post-operative period, and the role of chemotherapy in the presence of immunosuppressive therapy is discussed.

Carcinoma, Squamous Cell↗
PubMed1991

Relation of central obesity and insulin resistance with high diabetes prevalence and cardiovascular risk in South Asians.

The hypothesis that the high mortality from coronary heart disease (CHD) in South Asians settled overseas compared with other populations is due to metabolic disturbances related to insulin resistance was tested in a population survey of 3193 men and 561 women aged 40-69 years in London, UK. The sample was assembled from industrial workforces and general practitioners' lists. In comparison with the European group, the South Asian group had a higher prevalence of diabetes (19% vs 4%), higher blood pressures, higher fasting and post-glucose serum insulin concentrations, higher plasma triglyceride, and lower HDL cholesterol concentrations. Mean waist-hip girth ratios and trunk skinfolds were higher in the South Asian than in the European group. Within each ethnic group waist-hip ratio was correlated with glucose intolerance, insulin, blood pressure, and triglyceride. These results confirm the existence of an insulin resistance syndrome, prevalent in South Asian populations and associated with a pronounced tendency to central obesity in this group. Control of obesity and greater physical activity offer the best chances for prevention of diabetes and CHD in South Asian people.

Adult↗
PubMed1991

A direct comparison of pharmacologic effects of retinoids on skin cells in vitro and in vivo.

The purpose of these studies was to directly compare the pharmacologic effects of retinoids on cutaneous cells in vitro and in vivo. Previously, it was demonstrated that all-trans-retinoic acid stimulates the proliferation of growth-arrested human keratinocytes and fibroblasts in culture. In the present studies, all-trans-retinoic acid was compared to three other retinoids--13-cis-retinoic acid, P-[(E)-2-(5,6,7,8-tetrahydro-5,5,8,8-tetramethyl-2-napthalenyl-1-p ropenyl] benzoic acid (TTNPB) and M-[(E)-2-(5,6,7,8-tetrahydro-5,5,8,8-tetramethyl-2-napthalenyl-1-p ropenyl] benzoic acid (meta-carboxy-TTNPB]--for growth stimulation using a cultured human squamous epithelial cell line (UM-SCC-1) and human dermal fibroblasts. These four retinoids were also evaluated for their effects on reduction of horn-filled utriculi when topically applied to the skin of rhino mice. All-trans-retinoic acid stimulated proliferation of both fibroblasts and epithelial cells over concentrations ranging from 0.01 to 1.0 micrograms/ml. In fibroblasts, 13-cis-retinoic acid was less potent than all-trans-retinoic acid, whereas, in epithelial cells these two retinoids were equipotent. In contrast, TTNPB was more potent than all-trans-retinoic acid at stimulating the growth of both fibroblasts and epithelial cells. The analog, meta-carboxy-TTNPB was essentially inactive as a growth stimulator of both cell types. In the rhino mouse utriculus reduction model, the rank order of potency for the retinoids was the same as that for in vitro cell growth stimulation (TTNPB greater than all-trans-retinoic acid greater than 13-cis-retinoic acid). Meta-carboxy-TTNPB was inactive at reducing utriculi at a dose of 5,000 times the ED50 of TTNPB.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

Inhibition of epithelial cell adhesion by retinoic acid. Relationship to reduced extracellular matrix production and alterations in Ca2+ levels.

Human squamous epithelial cells maintained in growth factor-deficient medium were examined for sensitivity to all-trans retinoic acid (retinoic acid). Under conditions of low external Ca2+ (0.15 mmol/l [millimolar]), or high external Ca2+ (1.4 mmol/l), retinoic acid stimulated proliferation. Concomitantly, cell-substrate adhesion was decreased. Enzyme-linked immunosorbent assays were used to assess production of two extracellular matrix components, ie, fibronectin and thrombospondin. In the presence of retinoic acid, production of both was decreased. Because both fibronectin and thrombospondin serve as epithelial cell adhesion factors, the decreased production of these moieties could contribute to reduced adhesion. Using 45Ca2+ to measure total cell-associated Ca2+ and the Ca2(+)-sensitive dye Indo-1 to measure intracellular free Ca2+, it was found that concentrations of retinoic acid that altered cell-substrate adhesion in the squamous epithelial cells had no effect on total, cell-associated Ca2+, but reduced intracellular free Ca2+ by 50% to 60%. Because Ca2+ is a regulator of adhesion, the ability of retinoic acid to modulate Ca2+ levels in the squamous epithelial cells may explain, in part, how retinoic acid influences their adhesiveness.

Calcium↗
PubMed1989

Influence of thymoxamine eye-drops on the mydriatic effect of tropicamide and phenylephrine alone and in combination.

In a preliminary experiment in 12 healthy volunteers, one drop of thymoxamine 0.5% instilled into the conjunctival sac completely reversed the mydriasis produced by phenylephrine 2.5%, 5% and 10% after 20 minutes. In a second study in eight volunteers, thymoxamine 0.5% completely prevented the mydriasis produced by phenylephrine 2.5% and produced a miosis. It also completely reversed the mydriasis produced by tropicamide 0.5%. The mydriatic effect of tropicamide 0.5% plus phenylephrine 2.5%, however, was not completely reversed by thymoxamine 0.5% over a period of 180 minutes. Phenylephrine, tropicamide and thymoxamine are freely available for use by registered optometrists.

Adolescent↗
PubMed1989

A newer avenue for evaluation of thyroid dysfunction.

Attempt has been made to rationalise the biochemical assessment of patients suspected to have thyroid dysfunction by introduction of a new rapid and supersensitive immunoradiometric assay (IRMA) for TSH. 294 patients were subjected to thyroid investigation viz; tT3, tT4 and TSH (IRMA). Of these, 51 (17.34%) were hypothyroid, 22 (7.48%) were hyperthyroid and 221 (75.1%) were euthyroid. The ratio of thyroid disorder in male to female was 1:3.38. In all patients with hyperthyroidism TSH (IRMA) was 0.05 to undetectable and it was more than 4.5 ulu/ml in hypothyroid patients. TSH (IRMA) was low in one euthyroid patient a 0.34% incidence of false negativity. In 2 patients with subclinical hyperthyroidism TSH (IRMA) was low while tT3 and tT4 were normal. TSH (IRMA) therefore may obviate the need for more time consuming and expensive TRH test and simplify the approach to thyroid function tests in patients suspected to have masked or overt hyperthyroidism.

Adolescent↗