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Biomedical subjects

J Shah

Publications and source records attributed to J Shah.

At least 127 records · Page 7Linked to original sources
PubMed1998

Factors affecting the outcome in 50 cases of scaphoid nonunion treated with Herbert screw fixation.

Our experience in the treatment of 50 scaphoid nonunions treated with Herbert screw fixation is reviewed. Success rates fell off as the duration of nonunion before treatment increased. However, this appeared to be related to the increased incidence of avascular necrosis with time rather than simply the factor of time alone. In this series the major adverse determinants for outcome were avascular necrosis and a history of previous surgery for nonunion. Failure to graft in a selected group with an intact cartilaginous envelope or a stable firm fibrous union did not affect results. The heterogeneous nature of any series of scaphoid nonunions is emphasized and the difficulties in comparing results with cohorts unmatched for the various adverse factors discussed is stressed.

Adolescent↗
PubMed1998

Combined topical-peribulbar anesthesia for cataract surgery.

PURPOSE: To evaluate the anesthetic effect of single-point low-volume peribulbar anesthesia supplemented by topical anesthesia. SETTING: Private ambulatory ophthalmic practice. METHODS: Five hundred consecutive patients received 4 cc of lidocaine 2% with 200 units hyaluronidase as 1-point peribulbar anesthesia. This was supplemented by lidocaine 4%, 1 drop every 3 to 5 minutes for 3 instillations. Phacoemulsification and intraocular lens implantation were performed through a scleral tunnel or clear corneal approach. All patients were evaluated for intraoperative akinesia, lid closure, and anesthesia. One hour after surgery, the eye patch was removed and patients were evaluated for pain, discomfort, foreign-body sensation, diplopia, and lid closure. RESULTS: All patients had no pain to mild discomfort during surgery; 34% had total and 58% partial akinesia; 78% had poor orbicularis action (lid closure); 12% had subconjunctival hemorrhage. Postoperatively, 42% of patients had foreign-body sensation caused by conjunctival coaptation by diathermy or corneal edema. Diplopia occurred in 32% of patients but resolved within 1 hour after eye-patch removal, and partial ptosis occurred in 58%, resolving within 2 hours of patch removal. All patients had normal lid closure when the eye patch was removed. CONCLUSIONS: Low-volume 1-point peribulbar anesthesia supplemented by topical anesthesia was safe and effective and provided early visual recovery. Topical therapy can be started 1 hour postoperatively.

Administration, Topical↗
PubMed1998

In-vivo tissue uptake and retention of Sn-117m(4+)DTPA in a human subject with metastatic bone pain and in normal mice.

Organ and tissue uptake and retention of Sn-117m(4+)DTPA were studied in a human subject treated for metastatic bone pain, and the results were compared with the biodistribution studies in five normal mice. The explanted organs from a patient who received a therapy dose of 18.6 mCi (688.2 MBq) Sn-117m(4+)DTPA and who died 47 days later were imaged with a gamma-camera, and tissue samples were counted and also autoradiographed. Bone, muscle, liver, fat, lungs, kidneys, spleen, heart and pancreas tissue samples were assayed in a well counter for radioactivity. Regions of interest were drawn over bone and major organs to calculate and quantify clearance times using three in vivo Sn-117m(4+)DTPA whole-body scintigrams acquired at 1, 24 and 168 h after injection. Five normal mice injected with the same batch of Sn-117m(4+)DTPA as used for the human subject were sacrificed at 24 h, and tissue samples were collected and assayed for radioactivity for comparison with the human data. For the human subject, whole-body retention at 47 days postinjection was 81% of the injected dose, and the rest (19%) was excreted in urine. Of the whole-body retained activity at 47 days, 82.4% was in bone, 7.8% in the muscle and 1.5% in the liver, and the rest was distributed among other tissues. Gamma-ray scintigrams and electron autoradiographs of coronal slices of the thoracolumbar vertebral body showed heterogeneous metastatic involvement with normal bone between metastatic lesions. There was nonuniform distribution of radioactivity even within a single vertebral body, indicating normal bone between metastatic lesions. Lesion-to-nonlesion ratios ranged from 3 to 5. However, the osteoid-to-marrow cavity deposition ratio, from the microautoradiographs, was 11:1. The peak uptake in the human bone was seen at 137 h with no biological clearance. Soft tissues showed peak uptake at 1 h and exhibited three compartmental clearance components. Whole-body retention in normal mice was 38.7% of the injected dose at 24 h and the rest was excreted. At 24 h postinjection, bone in mice showed 84.2% of the whole-body retention, muscle 1.7% and liver 1.4%, and the rest was distributed in other soft tissues. Percent distribution of the retained dose among bone, muscle, liver and other soft tissues is very similar between mice and a human subject. To calculate precise radiation absorbed doses from bone pain palliation radionuclides, it is necessary to take into account soft-tissue uptake and retention that may not be readily evident from routine external gamma-scintigraphy.

Adenocarcinoma↗
PubMed1998

Performance incentives and means: how regulatory focus influences goal attainment.

Study 1 demonstrated that as individuals' promotion-related ideal strength increases, performance on an anagram task is greater for a monetary task incentive framed in terms of gains and nongains (i.e., promotion framed) than one framed in terms of losses and nonlosses (i.e., prevention framed), whereas the reverse is true as individuals' prevention-related ought strength increases. Study 2 further demonstrated that with promotion-framed task incentives, individuals' ideal' strength increases motivation for promotion-related goal attainment means (gaining points), whereas with prevention-framed task incentives, individuals' ought strength increases motivation for prevention-related means (avoiding losing points). These results suggest that motivation and performance are greater when the regulatory focus of task incentives and means match (vs. mismatch) the chronic regulatory focus of the performers.

Achievement↗
PubMed1998

Hall effect imaging.

This paper presents a new imaging method based on the classical Hall effect (HE), which describes the origin of a detectable voltage from a conductive object moving in a magnetic field. HE images are formed using ultrasound imaging techniques in a magnetic field. These images reflect the electrical properties of the sample. To demonstrate the feasibility of this method, images of plastic and biological samples are collected. The contrast mechanism and signal-to-noise issues are discussed. Since electrical parameters vary widely among tissue types and pathological states, HE imaging may be a useful tool for biological research and medical diagnosis.

Adipose Tissue↗
PubMed1997

Percutaneous permeation of N,N-diethyl-m-toluamide (DEET) from commercial mosquito repellents and the effect of solvent.

N,N-Diethyl-m-toluamide (DEET), the active ingredient in many commercial mosquito repellents, is thought to be responsible for a wide range of local and systemic adverse reactions following its use. Many investigators have studied the dermal absorption of pure DEET; however, there is only one report in the literature on the absorption of DEET from commercial mosquito repellents and the effect of concentration of DEET on its absorption through skin. The first objective of the present study was to evaluate the permeation characteristics of DEET from four commercial products, Everglades (95%), Repel Deerhunters (52.25%), Off Skintastic (6.65%), and Skedaddle (6.2%), as compared to pure DEET (approximately 100%). The second objective was to study the effects of ethanol, the solvent for DEET, on the permeation of DEET and investigate its potential for enhancing the dermal absorption of DEET. Permeation studies of DEET from commercial mosquito repellents and from solutions containing various percentages of ethanol were conducted across human skin using an infinite dose technique with a Franz diffusion cell. Permeation parameters such as steady-state flux (Jss), lag time (tL), diffusion coefficient (D), permeability (P), and skin/ vehicle partition coefficient (K) were obtained from the permeation profiles in each case. The cumulative amount of DEET permeated can be ranked according to the following order: neat DEET (100%) = Everglades (95%) > Repel (52.25%) > Skedaddle (6.2%) = Off Skintastic (6.65%). Pure DEET exhibited the highest flux value of 63.20 +/- 24.52 micrograms/cm2-h, while Off Skintastic had the lowest value of 21.12 +/- 14.75 micrograms/cm2-h. The tL and D values for each of the products were similar to that of pure DEET. The total amount of DEET permeated from 30-45% ethanolic solutions at the end of 36 h was significantly higher than that from pure DEET and from the 60-90% ethanolic solutions. The Jss, P, and K values of DEET from the 30-45% ethanolic solutions were significantly higher than those from the 75-90% ethanolic solutions, while the tL and D values were similar for each solution. Therefore, there is potential for significant absorption of DEET after the dermal application of commercial mosquito repellents, and ethanol, used as a solvent, may enhance the permeation of DEET.

Analysis of Variance↗
PubMed1997

Oligomycin sensitivity conferring protein (OSCP) of bovine heart mitochondrial ATP synthase: high-affinity OSCP-Fo interactions require a local alpha-helix at the C-terminal end of the subunit.

Earlier studies on oligomycin sensitivity conferring protein (OSCP) of bovine mitochondrial ATP synthase (F1Fo) indicated that a deletion mutant form (CD-10), lacking the last 10 amino acid residues (K181-L190), was unable to bind to the Fo segment, or reconstitute energy-linked reactions in OSCP-depleted F1Fo complexes [Joshi et al. (1996) Biochemistry 35, 12094-12103]. So far as known, the K181-L190 region of all mammalian species of OSCP harbors four charged residues at positions 181, 184, 187, and 188, while secondary structure predictions suggest that the K178-M186 region has a high propensity to form a helix [Ovchinnikov et al. (1984) FEBS Lett. 166, 19-22; Higuti et al. (1993) Biochim. Biophys. Acta 1172, 311-314; Grinkevich et al. ( 1994) Biol. Membr. 11, 310-323; Engelbrecht et al. (1991) Z. Naturforsch., C: Biochem., Biophys., Biol.,Virol. 46, 759-764]. Present studies were undertaken to clarify the role of individual amino acids in the K181-L190 region in OSCP-stimulated energy coupling. Our data show that simultaneous replacements of all four charged residues by uncharged but polar glutamines, or of K181-R184 by apolar alanines, had no significant influence either on the total alpha-helix content of the mutant forms or on the ability of mutant OSCPs to couple energy-linked reactions. However, a substitution of the K181-M186 region by six proline residues led to complete loss in the coupling activity of the resultant mutant. A detailed analysis of the 6-proline mutant form revealed that the variant was indistinguishable from WT OSCP with respect to expression characteristics, affinity for S-Sepharose, and ability to interact with F1, but was unable to complex with the Fo segment. These studies suggest that the global protein structure was not destabilized. The helix potential prediction analyses showed that the 6-proline OSCP displayed a marked decrease in the helix-forming propensity in the region corresponding to residues 175-190. Quantitative CD analyses to measure helical content demonstrated that both of the mutant forms 6-proline-OSCP and CD-10 had a somewhat lower alpha-helical content compared to WT protein, while synthetic peptides corresponding in sequence to the K178-L190 region displayed a high propensity to form a helix. Taken together, these results suggest that the C-terminal end of OSCP encompasses an alpha-helix which is crucial for high-affinity interactions of the C-terminal end of this subunit with Fo in the F1Fo enzyme.

Adenosine Triphosphatases↗
PubMed1997

Emotional responses to goal attainment: strength of regulatory focus as moderator.

Goals with a promotion focus versus a prevention focus are distinguished. Chronic ideal goals (hopes and aspirations) have a promotion focus, whereas ought goals (duties and responsibilities) have a prevention focus. The hypothesis that emotional responses to goal attainment vary as a function of promotion versus prevention goal strength (conceptualized as goal accessibility) was tested in correlational studies relating chronic goal attainment (self-congruencies or self-discrepancies) to emotional frequency and intensity (Studies 1-3) and in an experimental study relating immediate goal attainment (i.e., success or failure) to emotional intensity (Study 4). All studies found that goal attainment yielded greater cheerfulness-dejection responses when promotion focus was stronger and greater quiescence-agitation responses when prevention focus was stronger.

Affect↗
PubMed1997

Expectancy x value effects: regulatory focus as determinant of magnitude and direction.

The authors propose that a promotion focus involves construal of achievement goals as aspirations whose attainment brings accomplishment. Commitment to these accomplishment goals is characterized by attempts to attain the highest expected utility. In contrast, a prevention focus involves construal of achievement goals as responsibilities whose attainment brings security. Commitment to these security goals is characterized by doing what is necessary. The different nature of commitment to accomplishment goals versus security goals is predicted to influence the interactive effect of goal expectancy and goal value on goal commitment, as evident in both task performance and decision making. Four studies found that the classic positive interactive effect of expectancy and value on goal commitment increases with a promotion focus and decreases with a prevention focus.

Decision Making↗
PubMed1997

Characterization of a salicylic acid-insensitive mutant (sai1) of Arabidopsis thaliana, identified in a selective screen utilizing the SA-inducible expression of the tms2 gene.

Salicylic acid (SA) plays an important signaling role in the resistance of many plants to pathogen invasion. Increases in endogenous SA levels have been associated with the hypersensitive response as well as systemic acquired resistance (SAR). SA also induces the expression of a subset of the pathogenesis-related (PR) genes. However, relatively little is known about the events occurring subsequent to SA accumulation during a resistance response. In order to identify mutations in components of the SA signal transduction pathway, we have developed a genetic screen in Arabidopsis thaliana that utilizes the Agrobacterium tumefaciens tms2 gene as a counter-selectable marker. SA-inducible expression of the tms2 gene from the tobacco PR-1a promoter confers sensitivity to alpha-naphthalene acetamide (alpha-NAM), resulting in inhibition of root growth in germinating transgenic Arabidopsis seedlings. Mutants in which root growth is insensitive to alpha-NAM have been selected from this PR-1a:tms2 transgenic line with the expectation that a subset will lack a regulatory component downstream of SA. The sail mutant so identified expressed neither the PR-1a:tms2 transgene nor the endogenous Arabidopsis PR-1, PR-2, and PR-5 genes in response to SA. These genes also were not induced in sai1 by 2,6-dichloroisonicotinic acid (INA) or benzothiadiazole (BTH), two chemical inducers of SAR. As expected of a mutation acting downstream of SA, sai1 plants accumulate SA and its glucoside in response to infection with an avirulent pathogen and are more susceptible to this avirulent pathogen than the wild-type parent. sai1 is allelic to npr1, a previously identified SA-noninducible mutation. The recessive nature of the noninducible sai1 mutation suggests that the wild-type SAI1 gene acts as a positive regulator in the SA signal transduction pathway.

Amidohydrolases↗
PubMed1997

Worldwide variations in prevalence of symptoms of allergic rhinoconjunctivitis in children: the International Study of Asthma and Allergies in Childhood (ISAAC).

BACKGROUND: As part of the International Study of Asthma and Allergies in Childhood (ISAAC), prevalence surveys were conducted among representative samples of school children from locations in Europe, Asia, Africa, Australia, North and South America. SUBJECTS: 257,800 children aged 6-7 years from 91 centres in 38 countries, and 463,801 children aged 13-14 years from 155 centres in 56 countries. METHODS: Written symptom questionnaires were translated from English into the local language for self-completion by the 13-14-year-olds and completion by the parents of the 6-7-year-olds. Rhinitis was described as a problem with sneezing, or a runny, or blocked nose when you (your child) DID NOT have a cold or the flu. Additional questions were asked about rhinitis associated with itchy-watery eyes, interference with activities and a history of hay fever ever. RESULTS: The prevalence of rhinitis with itchy-watery eyes ("rhinoconjunctivitis") in the past year varied across centres from 0.8% to 14.9% in the 6-7-year-olds and from 1.4% to 39.7% in the 13-14-year-olds. Within each age group, the global pattern was broadly consistent across each of the symptom categories. In centres of higher prevalence there was great variability in the proportion of rhinoconjunctivitis labelled as hay fever. The lowest prevalences of rhinoconjunctivitis were found in parts of eastern Europe, south and central Asia. High prevalences were reported from centres in several regions. CONCLUSION: These results suggest substantial worldwide variations in the prevalence and labelling of symptoms of allergic rhinoconjunctivitis which require further study. These differences, if real, may offer important clues to environmental influences on allergy.

Adolescent↗
PubMed1996

Oligomycin sensitivity conferring protein of mitochondrial ATP synthase: deletions in the N-terminal end cause defects in interactions with F1, while deletions in the C-terminal end cause defects in interactions with F0.

The structure/function relationships of oligomycin sensitivity conferring protein (OSCP) of bovine mitochondrial ATP synthase were studied by nested deletion mutagenesis, followed by analyses of the resultant OSCPs for their ability to restore partial reactions of ATP synthesis in OSCP-depleted F1-F0 complexes. Our results indicate that, from the N-terminus of OSCP, up to 13 amino acid residues could be deleted without any effect on OSCP coupling activity. However, deletion of 16 or more residues led to a slow decline in the ability of resultant mutant forms to restore ATP synthesis. Compared to the wild-type form of OSCP, deletion mutant ND-28 (deletion of residues 1-28) is 50% as active in its ability to reconstitute ATP-Pi exchange activity. Detailed analyses of mutant ND-28 revealed that it was able to bind to the membrane segment (F0) of ATP synthase and restore oligomycin-sensitive ATPase activity in OSCP-depleted F1-F0 complexes. However, it did not bind to soluble segment F1, nor did it confer cold stability to either soluble F1 or reconstituted F1-F0 complex. On the other hand, studies on nested deletions on the C-terminal end indicate that three residues could be deleted without compromising the energy-coupling activity of OSCP. However, truncations of five or more residues caused an impairment in the ability of resultant mutant forms to restore ATP-Pi exchange activity in OSCP-depleted complexes. Mutant CD-10 (deletion of amino acids 181-190) was completely ineffective as a coupling factor. Detailed analyses of this mutant revealed that the subunit was able to bind to soluble F1 segment and confer cold stability to the enzyme but was neither able to associate with the membrane segment (F0) nor able to reconstitute high oligomycin sensitivity in depleted F1-F0 complexes. We take these data to suggest that the N-terminal end of OSCP corresponding to residues G16-N28 is essential for binding of the coupling factor to soluble F1 but not for coupling the energy of proton translocation to the synthesis of ATP; on the other hand, the carboxyl-terminal end of OSCP containing amino acids K181-M186 is important for F0-OSCP interactions as well as for the coupling of the energy of delta microH+ during the synthesis of ATP. These results suggest a model for OSCP in which the N-terminus is associated with the F1 segment and the C-terminus is associated with the F0 segment, while the central part of the polypeptide forms three or more helices constituting the stalk in the intact F1F0 enzyme.

Adenosine Triphosphatases↗