The biocompatibility of rapidly degrading polymeric stents in porcine carotid arteries.

The goal of this study was to evaluate the biocompatibility of materials for use in fully bioabsorbable vascular stents. 10:90 poly(L-lactic-co-glycolic acid) (10:90 L-PLGA), 85:15 poly(L-lactic-co-glycolic acid) (85:15 L-PLGA), polydioxanone (PDO), and poly-L-lactic acid (L-PLA) polymers were chosen as materials. Polymeric fibers were woven into a braided structure with a mass equivalent to or greater than that expected for a vascular stent, secured to balloon-expandable bare metal stents and implanted into porcine carotid arteries. The in vivo response was analyzed at 30 and 90 days by angiography, histopathology, and histomorphometry. All vessels were patent at 30 and 90 days. Injury score and neointima formation was mild for all samples. The faster-degrading 10:90 L-PLGA had the highest inflammatory response at 30 days, but was completely absorbed with minimal inflammation and neointimal formation at 90 days. PDO showed signs of partial absorption at 90 days, while 85:15 L-PLGA and L-PLA demonstrated minimal absorption at 30 and 90 days. The inflammatory response to these three groups was similar over the experimental period. Using a robust materials-testing platform, we demonstrated long-term patency and intravascular biocompatibility of bioabsorbable polymers with varying rates of resorption. The data point to biocompatibility of a polymeric stent in the vascular space that is fully absorbable in less than a year.

Light-induced migration of retinal microglia into the subretinal space.

PURPOSE: To explore the effects of light exposure and deprivation on the distribution and function of microglia in the subretinal space of mice. METHODS: Using a monoclonal antibody, 5D4, that identifies resting, ramified microglia, the distribution and density of microglia in the retina, and the subretinal space were determined by confocal microscopy and by immunohistochemistry of cryopreserved sections of eyes of albino and pigmented mice exposed to diverse levels of light, ranging from complete darkness to intense brightness. Axotomized retinal ganglion cells were retrograde labeled by fluorescent tracer to determine whether the marker colocalizes to 5D4+ cells. Electron microscopy was used to evaluate microglia for evidence of phagocytosis. RESULTS: 5D4+ microglia in pigmented eyes were limited to the inner retinal layers, but in albino eyes 5D4+ cells were found in the outer retinal layers and subretinal space as well. The subretinal space of eyes of albino mice raised from birth in complete darkness contained few 5D4+ cells, but exposure to light caused the rapid accumulation of 5D4+ cells at this site. 5D4+ cell density in the subretinal space correlated directly with intensity of ambient light. Retrograde labeling of axotomized ganglion cells resulted in 5D4+ cells in the subretinal space that contained the retrograde label. Subretinal microglia contained phagocytized rod outer segment discs. On intense light exposure, 5D4+ cells adopted an active morphology, but failed to express class II major histocompatibility complex (MHC) molecules. CONCLUSIONS: Light exposure induced retinal microglia migration into the subretinal space in albino mice. Subretinal microglia appeared to augment through phagocytosis the capacity of pigment epithelium to take up the photoreceptor debris of light toxicity. The unexpected presence of these cells in the subretinal space raises questions concerning their potential contribution to immune privilege in this space and to the fate of retinal transplants.

Evaluation of excretory/secretory products of larval Taenia solium as diagnostic antigens for porcine and human cysticercosis.

Excretory/secretory antigens (ES) of larval Taenia solium were obtained by maintaining the bladder worms in Medium 199 for 3 days. Analysis by SDS-PAGE showed that ES antigens consisted of at least 19 polypeptides, with M(r) ranging from 14-116 kDa. Analytical isoelectric focusing revealed eight bands with acidic pI. An immunocytolocalization study using the peroxidase method demonstrated the presence of ES epitopes on the tegument of the wall of the spiral canals of bladder worms. The specificity of ES antigens was evaluated by EITB, ELISA and FAST-ELISA using antisera against the common parasites of Chinese pigs and man. ES antigens cross-reacted with the antiserum against larval T. hydatigena of pigs. However, these antigens were generally more specific in diagnosing human cysticercosis. Three host-like molecules with molecular masses 43, 58 and 66 kDa were present in the ES products.

Specificity of isoelectric focusing-purified antigens in the diagnosis of human cysticercosis.

Specific antigens were isolated from the cystic fluid of larval Taenia solium by preparative isoelectric focusing (PIEF). A total of 20 fractions were produced by a rotating ampholine column with pI 3-10 ampholytes. The specificity of each fraction (F) was tested by double-antibody enzyme-linked immunosorbent assay (ELISA) using antisera from patients suffering from cysticercosis or one of six other parasitic diseases. F8-F15 cross-reacted strongly with sera from patients with hydatidosis. F9 and F10 also cross-reacted with the antisera against ascariasis and F15, with antisera against angiostrongylosis. However, F16 and F17 were highly specific as they yielded no cross-reaction with any of the heterologous antisera. PIEF is a good method for the production of specific antigens from larval T. solium because it is easy to perform and relatively inexpensive to run.

Effects of sorbitol dehydrogenase deficiency on nerve conduction in experimental diabetic mice.

In this report, we made use of sorbitol dehydrogenase (SDH)-deficient mutant mice (C57BL/LiA) to test whether there is a close correlation between the level of polyol accumulation and the degree of reduction in motor nerve conduction velocity (MNCV) associated with diabetes. The C57BL/LiA mouse has SDH deficiency due to a G-to-A mutation at the +1 position of intron 8, thus producing only aberrant SDH transcripts. These C57BL/LiA mice should have higher levels of polyol accumulation in the peripheral nerve because of the inability to further metabolize sorbitol to fructose. Here, we confirm by Western blot analysis and high-performance liquid chromatography that these mice lack SDH in the sciatic nerve and other various tissues, whereas normal mice possess SDH. These C57BL/LiA mice do not display any obvious phenotype that includes peripheral neuropathy in the normal laboratory environment and breed normally as described previously, although the tissues that normally contain SDH accumulate more sorbitol. This finding suggested that C57BL/LiA mouse strain is a valid model for studying the role in diabetic neuropathy of the polyol pathway, which consists of two enzymes-aldose reductase for converting glucose to sorbitol and SDH for converting sorbitol to fructose. Sorbitol levels in the sciatic nerve of diabetic C57BL/10N, nondiabetic, and diabetic C57BL/LiA mice were increased 4.3-, 16.6-, and 38.1-fold, respectively, above that of nondiabetic C57BL/10N. The fructose level in the sciatic nerve was increased 2.4-fold in diabetic C57BL/10N mice compared with that of nondiabetic and diabetic C57BL/LiA mice. Diabetic SDH-deficient mice showed an MNCV reduction similar in magnitude to that of diabetic C57BL/10N mice, despite greater nerve sorbitol accumulation and the lack of fructose in the former. The present data suggest that the levels of sorbitol and fructose in the sciatic nerve of mice do not correlate with the severity of MNCV deficit associated with diabetes.

Purification of larval Taenia solium antigens by isoelectric focusing.

By preparative isoelectric focusing in a rotating ampholine column, crude cystic membrane (M) or fluid (F) antigens of larval Taenia solium were each separated into 20 fractions. M fractions were less specific and sensitive than F fractions in detecting cysticercosis antibodies in pig serum. Among the F fractions, F15 showed the best potential to serve as a screening antigen. It contained 18 polypeptides, with pI 5.3-8.2 and a specific epitope of 25 kDa which was detected by immunoblotting. Although F15 showed slight cross-reactions with heterologous antisera in double-antibody IgG enzyme-linked immunosorbent assays (ELISA), it yielded the highest absorbance values when tested against homologous antisera. The antigen was used to screen sera samples from 4870 pigs slaughtered in Hong Kong and five other Chinese cities for cysticercosis antibodies by double-antibody ELISA, Falcon Assay Screening Test (FAST)-ELISA and enhanced chemiluminescent immunoassay. The results varied significantly between assays. However, the samples collected from Shenzhen yielded the highest positive rates. Enhanced chemiluminescent immunoassay based on camera-luminometry was found suitable for use under field conditions.

Influence of peripheral nerve grafts on the expression of GAP-43 in regenerating retinal ganglion cells in adult hamsters.

We have examined the ability of axotomized retinal ganglion cells in adult hamsters, to regenerate axons into a peripheral nerve graft attached to the optic nerve and the expression of GAP-43 by these neurons. We also examined the effect on these events of transplanting a segment of peripheral nerve to the vitreous body. The left optic nerves in three groups of hamsters were replaced with a long segment of peripheral nerve attached to the proximal stump of the optic nerve approximately 2 mm from the optic disc to induce regeneration of retinal ganglion cells into the peripheral nerve. An additional segment of peripheral nerve was transplanted into the vitreous of the left eye in the second group. The animals from the first and second groups were allowed to survive for 1-8 weeks and the number of regenerating retinal ganglion cells was determined by applying the retrograde tracer, Fluoro-Gold to the peripheral nerve graft and the expression of GAP-43 was studied by immunocytochemistry in the same retinas. As a control, a segment of optic nerve was transplanted into the vitreous body of the left eye in the third group of hamsters. These animals were allowed to survive for 4 weeks and the number of regenerating retinal ganglion cells was counted as in Groups 1 and 2. The percentages of the regenerating retinal ganglion cells which also expressed GAP-43 were very high at all time points in Group 1 (with no intravitreal peripheral nerve) and Group 2 (with intravitreal peripheral nerve) and at 4 weeks for the Group 3 (with intravitreal optic nerve) animals. In addition, the number of regenerating retinal ganglion cells, the number of retinal ganglion cells expressing GAP-43 and the number of regenerating retinal ganglion cells which also expressed GAP-43 were much higher in Group 2 than in Group 1 at all the time points and it was also much higher in Group 2 than in Group 3 at 4 weeks whereas there was no significant difference between the results from Groups 1 and 3 at 4 weeks. These data suggested that there was a close correlation between the number of the axotomized retinal ganglion cells regenerating axons into the peripheral nerve graft attached to the optic nerve and the expression of GAP-43.(ABSTRACT TRUNCATED AT 400 WORDS)