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Biomedical subjects

S Aziz

Publications and source records attributed to S Aziz.

134 records · Page 8Linked to original sources
PubMedDate not supplied

Bioresorbable microporous stents deliver recombinant adenovirus gene transfer vectors to the arterial wall.

The use of intravascular stents as an adjunct for percutaneous transluminal revascularization is limited by two principal factors, acute thrombosis and neointimal proliferation, resulting in restenosis. To overcome these limitations, we have investigated the potential of microporous bioresorbable polymer stents formed from poly(L-lactic acid) (PLLA)/poly(epsilon-caprolactone) (PCL) blends to function both to provide mechanical support and as reservoirs for local delivery of therapeutic molecules and particles to the vessel wall. Tubular PLLA/PCL stents were fabricated by the flotation-precipitation method, and helical stents were produced by a casting/winding technique. Hybrid structures in which a tubular sheath is deposited on a helical skeleton were also generated. Using a two-stage solvent swelling technique, polyethylene oxide has been incorporated into these stents to improve hydrophilicity and water uptake, and to facilitate the ability of these devices to function as drug carriers. Stents modified in this manner retain axial and radial mechanical strength sufficient to stabilize the vessel wall against elastic recoil caused by vasoconstrictive and mechanical forces. Because of the potential of direct gene transfer into the vessel wall to ameliorate thrombosis and neointimal proliferation, we have investigated the capacity of these polymer stents to function in the delivery of recombinant adenovirus vectors to the vessel wall. In vitro, virus stock was observed to readily absorb into, and elute from these devices in an infectious form, with suitable kinetics. Successful gene transfer and expression has been demonstrated following implantation of polymer stents impregnated with a recombinant adenovirus carrying a nuclear-localizing betaGal reporter gene into rabbit carotid arteries. These studies suggest that surface-modified polymer stents may ultimately be useful adjunctive devices for both mechanical support and gene transfer during percutaneous transluminal revascularization.

Adenoviridae↗
PubMedDate not supplied

Effect of cortisone on aspartate and alanine aminotransferases in a desert lizard.

1. Liver and serum aspartate aminotransferase (GOT) and alanine aminotransferase (GPT) activities were measured in a hibernating desert lizard, Uromastix hardwickii. The levels of both enzymes were found to be lower in hibernation than during the active period, particularly in the liver. 2. After intramuscular injection of 2 mg of cortisone acetate there was a rapid rise in the levels of these enzymes with a peak of 18 hours (GOT) and 12 hours (GPT). 3. The response of both enzymes to cortisone was much greater during the active period than during hibernation. 4. GOT showed a much more rapid and greater response to cortisone than GPT. This is in contrast to the response of rat liver where GPT is more responsive to this hormone. 5. These studies indicate that the transferase enzymes of this lizard differ from those of the rat in their sensitivity and time of response to cortisone.

Alanine Transaminase↗
PubMedDate not supplied

Comparative study of home blood glucose monitoring devices: Visidex, Chemstrip bG, Glucometer, and Accu-Chek bG.

Visidex (Ames Company, Elkhart, Indiana) and Accu-Chek bG (Bio-Dynamics, Boehringer Mannheim, Indianapolis, Indiana), two new devices for determining blood glucose at home, were compared with two older devices, Chemstrip bG (Bio-Dynamics) and Glucometer (Ames Company), and the standard laboratory glucose-oxidase method (Beckman autoanalyzer, Beckman Instruments, Fullerton, California). Laboratory serum glucose values up to 400 mg/dl had excellent overall correlation with Accu-Chek bG (r = 0.974), Glucometer (r = 0.974), Chemstrip bG (r = 0.963), and Visidex (r = 0.955). For glucose values less than or equal to 180 mg/dl, Glucometer had the best correlation (r = 0.921). For glucose values of 181-400 mg/dl, Accu-Chek bG had better correlation (r = 0.907) although Glucometer had closer mean value. Visidex was just as accurate as Chemstrip bG. Although the four devices tested tended to give lower values than the lab method, they are sufficiently accurate to be of clinical use in home monitoring of blood glucose. Meticulous care in running the tests is mandatory for accuracy. Individual differences among the four methods are discussed.

Autoanalysis↗
PubMedDate not supplied

Recurrent use of disposable syringe-needle units in diabetic children.

Fourteen insulin-dependent diabetic children reused their disposable syringe-needle units an average of 6.3 times per needle. Between uses, the needle was wiped with alcohol and stored in the refrigerator. There were no infections reported during the study for an average duration of 94 days. Dullness of the needle was the major reason for changing to a new one. Recurrent use of disposable needles for insulin injections appears safe in children and may be advised. It will help decrease some of the high cost of the daily care of a person with diabetes.

Adolescent↗
PubMedDate not supplied

University of Wisconsin solution provides superior myocardial preservation compared with Stanford cardioplegic solution.

The efficacy of the University of Wisconsin solution to safely prolong preservation times for kidney, pancreas, and liver transplantation is established, but its efficacy in enhancing myocardial preservation is not yet clear. We studied the effects of Stanford cardioplegic solution and the University of Wisconsin solution both in preserving the myocardium and in protecting it from the effects of reperfusion injury after 6 hours of preservation. In 28 rat hearts we measured changes in high-energy phosphate content (with magnetic resonance spectroscopy) and histologic changes (edema, endothelial changes, myocyte architecture) during preservation and changes in high-energy phosphate content, histologic status, and performance (aortic systolic and diastolic pressure, heart rate, rhythm) in Langendorff and working hearts during reperfusion. No significant differences in the kinetics of high-energy phosphate changes were noted between the two cardioplegic solutions during preservation. However, at the end of 6 hours of preservation, hearts in the Stanford cardioplegic solution group were more edematous (p < 0.01) than those in the University of Wisconsin group. During reperfusion, no significant differences in the kinetics of high-energy phosphates were noted between the two cardioplegic solutions. None of the hearts in the University of Wisconsin solution group developed ventricular fibrillation at the start of reperfusion, but all hearts in the Stanford group did so. Once sinus rhythm was established no significant differences in developed pressure or heart rate were found between the two solutions. After 2.5 hours of reperfusion, hearts in the Stanford group were more edematous (p < 0.002) and had a greater disruption of myocyte architecture (p < 0.002) and greater arteriolar endothelial injury (p < 0.004). In conclusion, the University of Wisconsin solution better protects the myocardium in this rat model than does Stanford solution. The mechanism for this beneficial effect of the University of Wisconsin solution appears to be due to its better preservation of the microvasculature rather than differences in preservation of high-energy phosphates.

Adenosine↗
PubMedDate not supplied

A reduction in accelerated graft coronary disease and an improvement in cardiac allograft survival using low molecular weight heparin in combination with cyclosporine.

Heparin compounds are a complex mixture of mucopolysaccharides that, in addition to their anticoagulant properties, have immunosuppressive activities and affect the reparative aspects of the response to arterial injury. Heparin inhibits smooth muscle cell migration and proliferation and can alter the accumulation of the components of the extracellular matrix after arterial injury. Heparin also interacts specifically with the endothelium. Our hypothesis was that if heparin compounds do affect the immune system, coagulation, smooth muscle cell proliferation, and the endothelium, then heparin combined with cyclosporine should improve allograft survival, reduce rejection, and prevent accelerated graft coronary disease. Low molecular-weight heparins are derived from the larger molecular-weight unfractionated heparin. We chose to use low molecular-weight heparins because of their longer half-life, better bioavailability, and decreased incidence of induced thrombocytopenia and bleeding. With a rat intraabdominal heterotopic model of heart transplantation (Lewis-Brown Norway to Lewis), low molecular-weight heparin in combination with a low dose of cyclosporine (0.5 mg/kg/day) significantly improved allograft survival compared to controls and either low molecular-weight heparin or cyclosporine alone. Histologically, smooth muscle cells are an important cellular component of the lesions of accelerated graft coronary disease. In comparison to animals treated with cyclosporine alone (2 mg/kg/day), the addition of low molecular-weight heparin to cyclosporine (2 mg/kg/day) reduced the frequency and the severity of accelerated graft coronary disease and the extent of parenchymal rejection.

Abdomen↗
PubMedDate not supplied

Transplant arterial vasculopathy: evidence for a dual pattern of endothelial injury and the source of smooth muscle cells in lesions of intimal hyperplasia.

With use of this straight artery model of transplantation for studying TGVD, we have shown the following: 1. Intimal thickening occurs in a time-dependent predictable manner only in allografts. 2. Endothelial injury as a result of procurement, preservation, and reperfusion by itself does not result in the development of intimal thickening. Additional endothelial injury associated with the presence of an early mononuclear infiltrate is necessary for the development of TGVD. 3. The development of intimal hyperplasia is initially cellular, consisting mainly of macrophages and a smaller proportion of lymphocytes. The macrophages are later replaced by SMCs. These findings are summarized in Figure 16. 4. The source of the SMCs in intimal lesions is most likely the recipient media.

Animals↗