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  • 1
    Online Resource
    Online Resource
    A Biaxial Strain–Based Expansion Mechanism for Auxetic Stent Deployment
    SAGE Publications ; 2017
    In:  Journal of Applied Biomaterials & Functional Materials Vol. 15, No. 3 ( 2017-01), p. 196-205
    Details
    In: Journal of Applied Biomaterials & Functional Materials, SAGE Publications, Vol. 15, No. 3 ( 2017-01), p. 196-205
    Abstract: Auxetics, a special class of materials, tend to expand both in the radial and longitudinal directions when a unidirectional tensile force is applied. Recently, studies have come up with new designs for auxetic vascular and nonvascular stents which are deployed with commercial balloon catheters. There are some inherent limitations associated with a unidirectional application of expansion force in the effective deployment of stents. This work proposed a solution to some of these limitations through the use of a biaxial mode of a predetermined strain-based expansion mechanism. Method The design incorporated a pressure-activated crank-slider mechanism. Fabrication of a prototype for experimental verification was carried out through milling and high-speed lathe machining. The testing of the device employed the use of auxetic stents, fabricated from a biocompatible polymer. A finite element study is presented to extrapolate experimental results to a broader range of operation and working conditions. Results and Conclusions The expansion mechanism is similar in operation to the opening of an umbrella. The length of the connected auxetic stent increases when internal hydraulic pressure is applied. The degree of linear expansion in 1 direction influences the expansion of auxetic stent in the lateral direction. As the device exerts pressure longitudinally, a larger amount of the force is distributed on the unit cells/hinges which ultimately results in an increased expansion of the stent.
    Type of Medium: Online Resource
    ISSN: 2280-8000 , 2280-8000
    URL: Article
    DOI: 10.5301/jabfm.5000326
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2017
    detail.hit.zdb_id: 2673624-X
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  • 2
    Online Resource
    Online Resource
    In Vitro Antioxidant Activities and the Therapeutic Potential of Some Newly Synthesized Chalcones Against 4-Acetaminophenol Induced Hepatotoxicity in Rats
    SAGE Publications ; 2021
    In:  Dose-Response Vol. 19, No. 1 ( 2021-01-01), p. 155932582199695-
    Details
    In: Dose-Response, SAGE Publications, Vol. 19, No. 1 ( 2021-01-01), p. 155932582199695-
    Abstract: The lack of safety and efficacy of existing hepatoprotective agents urge the need to explore novel hepatoprotective agents. The research work was planned to study the therapeutic potential of some newly synthesized chalcones against 4-acetaminophenol induced hepatotoxicity in rats. Male albino rats (N = 30) were divided into 6 groups of 5 animals each i.e. group I; Toxic control (4-acetaminophenol), group II; normal control (Normal saline), group III; Positive control (silymarin; 50 mg/kg bw) and groups IV-VI (test groups) treated with 3 chalcone analogues i-e 3a, 3f & 3 g (100, 150, 150 mg/kg bw, respectively). All the study group animals were administered with 4-acetaminophenol to induce hepatotoxicity except normal control. Following hepatotoxicity induction, test group animals were administered with selected doses of test compounds and toxic group animals left untreated. Liver enzymes including ALT, AST, ALP and serum bilirubin were determined photometrically. Antioxidant activities of test compounds were also determined. Histopathological examination of liver biopsies was also carried out through H & E staining. The test chalcones (3a, 3f & 3 g) significantly decreased the levels of liver enzymes and serum bilirubin toward normal and the pattern of results in the test group animals were comparable to silymarin administered animals indicating the hepatoprotective potential of test compounds. Moreover, the test chalcones (3a, 3f & 3 g) antagonized the effect of 4-acetaminophenol and thus, raised the catalase (CAT) and superoxide dismutase (SOD) while decreased the malondialdehyde (MDA) in experimental animals. The test chalcones (3a, 3f & 3 g) on histological examination of liver showed improvement of tissue morphology. The study concluded that the tested compounds have antioxidant potential and may act as hepatoprotective agent. However, in-depth studies are required to validate their safety and to elucidate the exact mechanism of action.
    Type of Medium: Online Resource
    ISSN: 1559-3258 , 1559-3258
    URL: Article
    DOI: 10.1177/1559325821996955
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2021
    detail.hit.zdb_id: 2440820-7
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  • 3
    Online Resource
    Online Resource
    Stroke Radiology and Distinguishing Characteristics of Intracranial Atherosclerotic Disease in Native South Asian Pakistanis
    SAGE Publications ; 2013
    In:  International Journal of Stroke Vol. 8, No. SA100 ( 2013-10), p. 14-20
    Details
    In: International Journal of Stroke, SAGE Publications, Vol. 8, No. SA100 ( 2013-10), p. 14-20
    Abstract: There are no descriptions of stroke mechanisms from intracranial atherosclerotic disease in native South Asian Pakistanis. Methods Men and women aged ≥18 years with acute stroke presenting to four tertiary care hospitals in Karachi, Pakistan were screened using magnetic resonance angiography/transcranial Doppler scans. Trial of ORG 10172 in Acute Stroke Treatment criteria were applied to identify strokes from intracranial atherosclerotic disease. Results We studied 245 patients with acute stroke due to intracranial atherosclerotic disease. Two hundred thirty scans were reviewed. Also, 206/230 (89·0%) showed acute ischaemia. The most frequent presentation was with cortically based strokes in 42·2% (87/206) followed by border-zone infarcts (52/206, 25·2%). Increasing degrees of stenosis correlated with the development of both cortical and border-zone strokes ( P = 0·002). Important associated findings were frequent atrophy (166/230, 72·2%), silent brain infarcts (66/230, 28%) and a marked lack of severe leukoaraiosis identified in only 68/230 (29·6%). A total of 1870 arteries were studied individually. Middle cerebral artery was the symptomatic stroke vessel in half, presenting with complete occlusion in 66%. Evidence of biological disease, symptomatic or asymptomatic was identified in 753 (40·2%) vessels of which 543 (72%) were significantly ( 〉 50%) stenosed at presentation. Conclusion Intracranial atherosclerotic disease is a diffuse process in Pakistani south Asians, with involvement of multiple vessels in addition to the symptomatic vessel. The middle cerebral artery is the most frequent symptomatic vessel presenting with cortical embolic infarcts. There is a relative lack of leukoaraiosis. Concomitant atrophy, silent brain infarcts and recent ischaemia in the symptomatic territory are all frequently associated findings.
    Type of Medium: Online Resource
    ISSN: 1747-4930 , 1747-4949
    URL: Article
    DOI: 10.1111/j.1747-4949.2012.00878.x
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2013
    detail.hit.zdb_id: 2211666-7
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