ISSN:0277-3740    

出版商:OVID    

年代:1994

数据来源: OVID

摘要:

In this article we develop a calculation or formula for use in determining the potential dilution effect of fluids administered during patient treatment on serologic testing parameters. The formula uses basic principles of (a) fluid distribution over time from administration; (b) ratios of plasma and extravascular fluid volumes to body weight; and (c) common practices of fluid resuscitation. A dilution threshold of 50% was set using data from enzymelinked immunosorbent assay human immunodeficiency virus antibody determinations performed on in vitro diluted seropositive serum samples. These data respond to issues raised by guidelines from the Centers for Disease Control and the U.S. Food and Drug Administration to achieve recipient safety without unnecessarily restricting the potential donor pool.

ISSN:0277-3740    

出版商:OVID    

年代:1994

数据来源: OVID

摘要:

Three corneoscleral discs (from two donors) underwent subtotal endothelial loss during routine “long-term” organ culture storage. Laboratory studies of these corneas revealed evidence of herpes simplex virus (HSV) infection. The fellow cornea from one of the donors had been issued for transplant to a patient with keratoconus. Deterioration of the graft was noted 5 days after surgery; the disc was removed at 2 months and was shown to be infected with HSV. In an experiment designed to simulate initial “cleansing” of donor globes, 0.1% polyvinylpyrolidone-iodine protected cells from infection with HSV. It was concluded that the detection of HSV in these corneas could not be explained by external contamination of the ocular surface. Furthermore, culture of conjunctival and pharangeal swabs taken from 47 consecutive donors confirmed that HSV is rarely isolated at or around the time of death. Five pairs of donor corneas destined for use in transplantation were selected at random and investigated for the presence of HSV. HSV DNA was detected by polymerase chain reaction (PCR) in tissue from two of the corneal donors. Sequential stepwise sectioning suggested that HSV DNA when present was distributed in discrete foci within the cornea. These observations suggest that HSV infection may be a cause of severe endothelial loss during corneal organ culture and possibly provide an explanation for some “failures” of corneal grafting.

ISSN:0277-3740    

出版商:OVID    

年代:1994

数据来源: OVID

摘要:

Twenty-four pair of eyes donated to the Minnesota Lions Eye Bank were studied to determine the effect of corneal procurement methods on tissue quality. Eyes studied were ineligible for transplantation because of a preexisting medical condition other than sepsis or age of > years. The procurement technique was randomized for each donor. One cornea was procured in situ (IS), whereas the fellow eye was enucleated and processed in the laboratory (EN). Procurement protocols were standard Eye Bank Association of America methods. Tissue characteristics were scored according to standard eye bank protocols. Cultures were performed at the time of tissue procurement and following storage for 7 days in Dexol media. With the exception of endothelial striae, no statistical difference was found between groups for any tissue characteristics. The average score for endothelial striae in the IS group was greater than twice that of the EN group. Initial cultures were positive in 10 of 24 in the IS group and four of 24 in the EN group. Each group had three positive end-storage cultures. These results demonstrate superior tissue decontamination after initial processing and less endothelial cell trauma with standard enucleation when compared to in situ corneal excisions.

ISSN:0277-3740    

出版商:OVID    

年代:1994

数据来源: OVID

摘要:

Primary graft failure is a rare but major complication of penetrating keratoplasty. An apparent clustering of four cases during a 1-month period led to a review of all 778 keratoplasties performed by nine surgeons at Massachusetts Eye and Ear Infirmary from July 1, 1986 to June 30, 1988. The objectives of this study were (a) to investigate the possibility that cases of primary graft failure occurred in clusters within their physical environment of space, time, and personnel and (b) to determine the frequency of and evaluate possible risk factors for primary graft failure. Twenty-one cases of primary graft failure were found, resulting in an incidence rate of 2.7% during this period. A 13.3% incidence of primary graft failure was found in donor mates, suggesting improper tissue preparation. The charts and eye bank records of the 21 cases and 84 age-matched controls, randomly selected from the group of all keratoplasties, were reviewed for donor-, recipient-, surgeon-, and surgery-related characteristics. Improper tissue preparation was not associated with primary graft failure. An individual surgeon was the most significant risk factor [odds ratio=6 (95% CI: 2.1-17.0)].

ISSN:0277-3740    

出版商:OVID    

年代:1994

数据来源: OVID

摘要:

Kinetic changes of inflammatory cells and major histocompatibility (MHC) antigenic markers in syngeneic and allogeneic corneal grafts in rats were studied. Syngeneic grafts demonstrated mild inflammation in the first week with macrophages and T-helper/inducer cells found in a 2:1 ratio. By week 2 fewer macrophages were seen, and by week 4 no inflammatory cells were seen in the central graft. Central keratocytes and endothelium were negative for class II MHC expression. Significant inflammation persisted adjacent to the wound with macrophages and T-helper/inducer cells seen surrounding the sutures. Allogeneic grafts in the first week demonstrated mild inflammation with macrophages and T-helper/inducer cells in a 2:1 ratio. The central graft in week 2 had increased numbers of T-helper/inducer cells and T-suppressor/ cytotoxic cells. By the third and fourth week, the T-suppressor/ cytotoxic cells had become the major infiltrating cell. MHC class II antigens were seen on inflammatory cells, keratocytes, donor, and recipient endothelium.

ISSN:0277-3740    

出版商:OVID    

年代:1994

数据来源: OVID

摘要:

Using a vascularized cornea rabbit model closely resembling human high-risk keratoplasty, corneal allografts were performed on three groups of animals that were paired and tested preoperatively by mixed lymphocyte cultures (MLCs). The three groups were group A, unmodified controls with clear corneas; group B, untreated animals with vascularized corneas; and group C, animals treated with topical cyclosporine (CSA) with vascularized corneas. The MLC results were expressed as stimulation indices (Sis) and divided into low (SI ≤ 20) and high (SI>20) responders and were correlated with final outcome of grafts using survival analysis estimates. In group A, five of 13 (38.5%) grafts rejected, the chance of failure depending on the degree of MLC mismatch between donor and recipient (p=0.02). All allografts in group B rejected regardless of the degree of mismatch. In group C, seven of 12 (58.3%) grafts rejected, indicating that topical CSA significantly improved survival (p=0.003) compared with group B. Grafts with mild degrees of MLC mismatch (low responders) survived better (p=0.0003) than did higher degrees of MLC mismatch (high responders), all of which rejected despite treatment. Our results indicate that both corneal vascularization and the degree of donor-recipient matching play important roles in determining corneal graft survival.

ISSN:0277-3740    

出版商:OVID    

年代:1994

数据来源: OVID

摘要:

Seven corneas ranging in age from 20 weeks of gestation to 6 months after birth were studied and changes observed in five layers. The epithelium thickens through the addition of new cellular layers and the enlargment of cells. The way junctional complexes develop with age is described. The way the collagen fibrils in Bowman's layer is arranged changes over time. The layer arrangement and orientation of the stroma's collagen fibrils are described at different stages of development. The keratocytes progressively flatten out and gather together. The thickness of Descemet's membrane increases from 0.6 m at 20 weeks of gestation to 4 m at 6 months. During the prenatal period, the banded layer appears with cross-linking bridges. The nonbanded layer appears after birth. Several changes were found in the endothelium: flattening out of the initially cube-shaped cells and changes in the intercellular junctions that can be seen from 20 weeks of fetal life. At 20 and 25 weeks of gestation, two layers of cells were observed in the corneal midperiphery. The adult structure of the cornea was reached at about 6 months after birth.

ISSN:0277-3740    

出版商:OVID    

年代:1994

数据来源: OVID

摘要:

Ninety-nine eyes with keratoconus of 64 patients were examined using the sagittal radii method to determine the corneal flattening and compared with 100 eyes of 50 healthy controls. To express the degree of this flattening, four numerical eccentricity (E) values for each eye were calculated. The highest E value of the four was chosen as a parameter for diagnosis of the disease. In keratoconus patients in whom the highest E values of keratoconus eyes were 3=0.8, the specificity of the test was 98% and the sensitivity was 97%. This abnormal eccentricity was observed in keratoconus eyes with a visual acuity of 1.0, whereas slit-lamp examination showed no abnormalities. This study demonstrates that eccentricity can be helpful to diagnose keratoconus at an early stage.

ISSN:0277-3740    

出版商:OVID    

年代:1994

数据来源: OVID

摘要:

Tryptase is useful as a specific and accurate indicator of mast cell activation, whereas histamine, a mast cell's major mediator, also exists in basophils. The aim of this study is to investigate histamine and tryptase levels in allergic conjunctiva. We measured histamine and tryptase levels in conjunctival epithelial cell suspension of children with allergic conjunctivitis (AC) and vernal keratoconjunctivitis (VKC), and controls, and we evaluated correlations with clinical observations. Both the histamine and tryptase levels in VKC were significantly higher than controls (p <0.05, p< 0.01), and histamine levels in VKC was also greater than AC (p <0.05). The histamine/ tryptase (H/T) ratios were 0.03 ± 0.04 in AC, 0.08 ± 0.09 in VKC and 0.006 ± 0.006 in controls. The H/T ratios in VKC were significantly higher than controls (p <0.05) and AC (p <0.05), and were also found to correlate with the superficial punctate keratopathy (SPK) score (r2=0.89). Analyzing the histamine and tryptase levels in conjunctival epithelium may be useful in evaluating the allergic ocular surface, especially in the cases with SPK, where the increase in the histamine levels is not accompanied by an increase in tryptase levels. This suggests an important role for inflammatory cells such as basophils infiltrating into the conjunctival epithelium in allergic reactions.

ISSN:0277-3740    

出版商:OVID    

年代:1994

数据来源: OVID