摘要:

Purpose. A device that releases cyclosporine and dexamethasone into the eye for extended periods of time might be beneficial in diseases such as proliferative vitreoretinopathy and uveitis. In this study we examine the pharmacokinetics and toxicity of cyclosporine and dexamethasone combined in an intravitreal sustained-release device and the toxicity of a similar device containing only dexamethasone in rabbits.Methods. Rabbits were divided into three groups for (1) evaluation of the drug tissue levels and device release kinetics following implantation of a device containing 100μg of cyclosporine labeled with 2μCi of3H-cyclosporine and 2 mg of dexamethasone; (2) evaluation of the toxicity of this intravitreal device; and (3) evaluation of the toxicity of a similar device containing 2 mg of dexamethasone only. Cyclosporine was measured using a scintillation counter and dexamethasone was measured by high pressure liquid chromatography (HPLC). Toxicity was evaluated by electroretinography, clinical examination, and light microscopy.Results. Vitreous concentrations of cyclosporine (±standard deviation) averaged 0.06 (±0.02)μg/ml over 10 weeks. The average dexamethasone concentration over the 10 week period was 2.9 (±0.9)μg/ml. Devices containing cyclosporine and dexamethasone released each drug at rates similar to devices containing cyclosporine or dexamethasone alone. Devices containing both cyclosporine and dexamethasone caused reversible depressions in the b-wave amplitude of photopic and scotopic electroretinograms (ERG's). There was no evidence of toxicity associated with the devices containing dexamethasone only. There was no drug-related toxicity evident on clinical or histopatho-logic examination of eyes with devices containing the combination of cyclosporine and dexamethasone or dexamethasone alone.Conclusions. We conclude that the device maintains potentially therapeutic levels of both cyclosporine and dexamethasone in the vitreous. Reversible electroretinographic abnormalities are attributable to cyclosporine. A sustained-release device containing cyclosporine and dexamethasone may be useful for reducing inflammation in diseases such as proliferative vitreoretinopathy and uveitis.

ISSN:0271-3683    

DOI:10.3109/02713689609000766

出版商:Taylor&Francis    

年代:1996

数据来源: Taylor

摘要:

Purpose. Glaucoma filtration surgery can fail in a minority of patients as a result of fibrosis in the subconjunctival bleb space and closure of the scleral fistula. In this study, the rat eye has been used as an experimental model for fistulising surgery in order to evaluate the clinical manifetation of bleb failure with the morphological evtns of the wound healing process.Methods. A conjunctival bleb was successfully formed in 25 rats and was examined daily using slit lamp microscopy to evaluate postoperative inflammation and the presence of a bleb. At defined post-operative time points, serial frozen sections of eyes were stained immunohistochemically using a panel of monoclonal antibodies directed against known surface markers on rat immune/inflammatory cells. Positively stained cells were counted (a) in the bleb site, (b) at the sclerostomy and (c) at the suture site.Results. Following an initial post-operative inflammation, a surgically formed sclerostomy and conjunctival bleb underwent a granulation and scarring response so that by 7-19 days the bleb had disappeared. Using the monoclonal antibodies applied in this study, it was possible to show that macrophages most likely play a major and pivotal role throughout the sequence of events that lead to repair of the fistula and closure of the bleb. It was also noted that the presence of an otherwise inert nylon suture used to close the incised conjunctiva can serve as a focus for macrophages.Conclusion. The rat has been successfully used as an experimental model of fistulising surgery and its subsequent failure. The use of a panel of monoclonal antibodies directed against specific surface markers on immune-inflammatory cells, highlighted macrophages to be prominent in all stages of this wound healing process.

ISSN:0271-3683    

DOI:10.3109/02713689609000767

出版商:Taylor&Francis    

年代:1996

数据来源: Taylor

摘要:

Purpose. This study was designed to evaluate the intraocular distribution and metabolism of the antiviral nucleotide analogs cidofovir and cyclic l-[(S)-3-hydroxy-2-(phosphonomethoxy) propyljcytosine (HPMPC) in New Zealand white rabbits following intravitreal administration.Methods. Male rabbits received either14C-cidofovir or14C-cyclic HPMPC by intravitreal injection into both eyes (50μg/eye, 11μCi/eye). Two animals per group were sacrificed at 24, 48, 72 or 240 h post-dose. Ocular tissues, kidney and liver were oxidized to determine total radioactivity and metabolites were determined by HPLC.Results. At 24 h post-dose, total radioactivity was 9.96 and 5.18μg-equiv/g for cidofovir and cyclic HPMPC, respectively, in vitreous and 20.9 and 3.54μg-equiv/g, respectively, in retina. Although the initial vitreal clearance was 2-fold faster for the cyclic analog, the estimated terminal elimination half-lives in vitreous (42 hr) and in retina (66-77 hr) were similar for both drugs. By 240 h post-dose, radioactivity in all ocular tissues was approximately ten-fold higher for cidofovir. Radioactivity in vitreous at 240 h after intravitreal dosing with either drug contained cidofovir, cyclic HPMPC and cidofovir-phosphocholine.Conclusions. The long retinal half-life observed presumably reflects formation of phosphorylated cidofovir within retinal cells. Cidofovir achieved a ten-fold higher level of phosphorylated drug in retina than cyclic HPMPC. Therefore, intravitreal cidofovir may be expected to suppress progression of retinitis for a longer period than an equivalent intravitreal dose of cyclic HPMPC. The intravitreal half-life of cidofovir was 20-fold longer than that of ganciclovir in the same animal model.

ISSN:0271-3683    

DOI:10.3109/02713689609000768

出版商:Taylor&Francis    

年代:1996

数据来源: Taylor

摘要:

Purpose. To integrate past biochemical findings with past morphological observations of area insoluble material isolated from cataract and aged normal lenses, by determining the spatial distribution ofα-crystallins associated with the plasma membrane (PM) of nuclear cataractous and age matched normal human lenses.Methods. Lenses were homogenized, pelleted and washed several times in 0.05M Tris-C1 (pH 7.2) containing 100mM KC1, 1 mM MgCl2and 2mM (β-mercaptoethanol, followed by several washes in 8M urea. Urea insoluble pellets (UIP) were labeled before fixation and embedding with rabbit serum raised againstα-crystallins, followed by goat anti-rabbit IgG conjugated to 5nm gold. Approximately 300 gold particles associated with the PM were counted, for each lens, on several electron microscopy (EM) micrographs. The number of gold particles/um of PM, number of individual vs clusters of gold particles were determined.Results. Micrographs from both normal and cataractous human lenses clearly demonstrated the association ofα-crystallins with the PM. Also apparent was the abundant labeling of the PM for cataractous lenses as compared to normal lenses. Quantification of the gold labeling revealed that not only was there an increase in the amount of labeling/um of PM in cataract lenses, but there was also an increased percentage of gold in clusters. These clusters were not only more numerous in cataractous lenses, but also contained a greater number of gold/cluster.Conclusions. These findings provide morphological evidence that the PM in nuclear cataract lenses is associated with large aggregates ofα-crystallin.

ISSN:0271-3683    

DOI:10.3109/02713689609000769

出版商:Taylor&Francis    

年代:1996

数据来源: Taylor

摘要:

Purpose. To develop an improved diagnostic test for rod-cone dysplasia type 1 (rcdl). Thercdlphenotype is an early onset, autosomal recessive disease caused by a mutation in the canine rod cyclic GMP phosphodiesterase (β-subunit (PDE6B) gene. A G to A transition in codon 807 at nucleotide position 2420 results in a stop codon. This is the only disease causing mutation detected so far in the canine PDE6B gene.Methods. Allele specific primers were designed in which the 3' end had the nucleotide corresponding to either the wild type or the mutantrcdlallele. PCR was done using the allele specific primers in combination with a common primer complementary to the opposite strand to distinguish between the wild type and thercdlalleles.Results. The wild type andrcdlalleles were identified successfully in two independent ASPCRs done with two different sets of allele specific primers. Further, both alleles could be amplified in a single tube and distinguished based on the size difference of the PCR products using one allele specific primer of altered length by the addition of a 9 nucleotide long linker.Conclusions. We have developed an improved diagnostic test for the disease based on ASPCR such that the presence or absence of different size amplified fragments provides direct determination of the genotype. In contrast to previously reported diagnostic tests, this method is more efficient because it eliminates the need for any further manipulation of the PCR product.

ISSN:0271-3683    

DOI:10.3109/02713689609000770

出版商:Taylor&Francis    

年代:1996

数据来源: Taylor