Significant Endothelial Changes Research Articles

Photorefractive Keratectomy Followed by Cross-linking Versus Cross-linking Alone for Management of Progressive Keratoconus: Two-Year Follow-up

To compare visual, refractive, topographic, and corneal higher-order aberration outcome at the 2-year follow-up after customized photorefractive keratectomy (PRK) followed by cross-linking (CXL) as a single procedure versus CXL alone in eyes with progressive keratoconus. Prospective, interventional, nonrandomized clinical trial. Seventeen patients (34 eyes) with progressive keratoconus were assigned to 2 groups: the worse eye (17 eyes) was assigned to the PRK plus CXL group and the better eye (17 fellow eyes) was assigned to the CXL group. In the PRK plus CXL group, uncorrected distance acuity improved significantly, from a mean ± standard deviation of 0.63 ± 0.36 logarithm of the minimal angle of resolution (logMAR) units to 0.19 ± 0.17 logMAR units (P < .05) and best distance acuity from 0.06 ± 0.08 logMAR to 0.03 ± 0.06 logMAR (P<.05). Manifest refraction spherical equivalent and spherical and cylindrical power improved significantly (P < .05). Simulated keratometry, flattest, steepest, average, cylindrical, apex keratometry, and inferior-superior value decreased significantly (P < .05). Total and coma-like aberrations significantly decreased for all pupil diameters (P < .05). In the CXL group, uncorrected distance acuity improved, but not significantly, from 0.59 ± 0.29 logMAR units to 0.52 ± 0.29 logMAR units, and best distance acuity improved from 0.06 ± 0.11 logMAR units to 0.04 ± 0.07 logMAR units (P > .05). Manifest refraction spherical equivalent and cylindrical power improvement was not significant (P > .05), unlike spherical power (P < .05). Steepest simulated keratometry, average simulated keratometry, and inferior-superior value significantly decreased (P < .05), unlike flattest simulated keratometry, cylindrical simulated keratometry, and apex keratometry (P > .05). Total and coma-like aberrations were not decreased significantly for all pupil diameters (P > .05). No significant endothelial changes were observed in either group. The PRK plus CXL procedure may bea good option to reduce corneal aberrations and stabilize corneas with progressive keratoconus.

Corneal Endothelial Changes Induced by Corneal Bee Sting Injury

Purpose: Corneal bee sting is a relatively rare injury. The authors report the significant endothelial changes despite complete resolution of corneal injury after a corneal bee sting. Case summary: Two males, ages 55 and 30, presented to our clinic for unilateral decreased visual acuity and eyeball pain after bee sting injuries. At the first visit, localized corneal stromal edema and epithelial defect were detected. One week after medical treatments, both patients achieved restoration of vision and resolution of corneal injury. In one patient, specular microscopy of the traumatized eye at one and five months showed a significant decrease in endothelial densities as compared with the contralateral eye. Conclusions: Corneal bee sting may cause significant endothelial changes despite complete resolution of clinical symptoms and injury. Specular microscopy should be considered in future intraocular surgeries.

In-Vitro Effects of Cardioplegic Solutions on Human Saphenous Vein Endothelium - a Scanning Electron Microscopy Study

In order to evaluate the effects of potassium cristalloid cardioplegic solutions (CPS) on the endothelial morphology, human saphenous veins were studied by scanning electron microscopy after exposure to three CPS named MKP (magnesium-potassium-procaine cardioplegia), LK (low-potassium cardioplegia), and HKA (high-potassium-albumin cardioplegia) and to their main components. Vein rings, selected from the saphenous veins sampled for graft harvesting in 63 patients undergoing aorto-coronary bypass surgery, were exposed for 30, 60, and 120 minutes to the following buffered solutions: Krebs bicarbonate (as control); MKP cardioplegia; KCl (16.0 mmol/L); MgCl2(2).6H2O (16.0 mmol/L); Procaine (0.05 mmol/L); NaCl (92.5 mmol/L); LK cardioplegia; KCl (10.0 mmol/L); Mannitol (74.3 mmol/L); Glucose (27.7 mmol/L); HKA cardioplegia; KCl (30 mmol/L). Severe endothelial lesions, consisting of diffuse disendothelialization and diffuse signs of endothelial suffering, were induced by KCl (30 and 16 mmol/L) after 60-120 min, and by MKP cardioplegia and KCl (10 mmol/L) after 120 min. Moderate endothelial lesions, characterised by diffuse endothelial surface changes and focal cellular loss, were induced by KCl (30 and 16 mmol/L) after 30 min, MKP cardioplegia and KCl (10 mmol) 30-60 min, LK cardioplegia, HKA cardioplegia, and MgCl2.6H2O after 120 min. Slight endothelial lesions, consisting of diffuse endothelial bulging, or absence of significant endothelial changes, were found in samples otherwise treated. Our findings showed a significant damaging effect of CPS on the human saphenous vein endothelium in-vitro. The endothelial lesions seemed related to the presence of potassium and magnesium, and to prolongation of the time of exposure to the cardioplegic solutions.(ABSTRACT TRUNCATED AT 250 WORDS)

Morphologic studies of acute rat cardiac allograft rejection across an isolated major histocompatibility complex class I (RT1A) disparity.

To define the morphologic correlates of acute rat cardiac allograft rejection across an isolated major histocompatibility complex (MHC) class I disparity, rejecting PVG.R1 cardiac allografts transplanted to (PVG x WF)F1 recipients were studied from days 4-8 posttransplantation. Documented ultrastructural tracer techniques as well as immunohistologic and immunoelectron microscopic methods were employed for morphologic analysis. Using intravenously administered horseradish peroxidase as a tracer probe for cell membrane permeability dysfunction, it was shown that severe diffuse loss of integrity of the microvascular endothelium preceded functional rejection, providing strong evidence that the allograft microcirculation is a central target of graft destruction. Also, rejection was associated with localized cardiac myofiber alterations prior to development of significant endothelial changes, indicating that cardiac muscle cells are additional cellular targets of immunologic injury. The ultrastructural features of progressive endothelial and myofiber injury, the predominance of MRC OX8+ lymphocytes and MRC OX6+ macrophages sequestered within the grafts, and the pattern of donor class I expression by allograft endothelium and cardiac myofibers were similar to those observed in rejecting allografts in full MHC-disparate combinations. Since it has been previously shown that MRC OX8+ class I-reactive T cells are absolutely required for rejection in this isolated class I-disparate model, the morphologic data raise the possibility that the OX8+ T lymphocyte subpopulation may also play a highly significant role in rat cardiac allograft rejection across a full MHC disparity.

Venous cryopreservation: Endothelial fibrinolytic activity and histology

Cryopreserved venous allografts have demonstrated excellent patency when used as arterial conduits after short-term storage. Maintenance of endothelial biochemical function after cryopreservation has not been documented. To date, the histologic data regarding changes in venous endothelium after cryopreservation have been variable. This study evaluates changes in canine jugular vein endothelial histology and fibrinolytic activity following cryopreservation. Compared to fresh, noncryopreserved veins there was no statistically significant difference in venous endothelial fibrinolytic activity after storage periods ranging from 24 hr to 3 months ( P < 0.05). Light microscopy failed to demonstrate significant endothelial changes between fresh, noncryopreserved veins and vein specimens from all storage periods; however, scanning electron microscopy demonstrated endothelial changes which appeared to linearly correlate with the duration of storage. Minimal endothelial changes were noted in all storage periods up to 1 month by scanning electron microscopy; however, after a 3-month storage there was widespread, severe endothelial injury. To the best of our knowledge, this report is the first documentation of maintenance of at least one endothelial biochemical parameter after venous cryopreservation. These data do not suggest, however, that cryopreserved venous endothelial cells can function normally after cryopreservation. Analysis of our combined fibrinolytic and histologic data suggests that cryopreservation can be used for the short-term storage (1 month) of viable venous allografts.

Observations on the ultrastructure of the tegument of Schistosoma mansoni in mesenteric veins.

The tegument of Schistosoma mansoni in situ in mesenteric veins was observed in mice with and without horseradish peroxidase injections. No evidence of incorporation of horseradish peroxidase into the tegument was noted after 45 minutes of high serum levels of peroxidase. Scant endogenous peroxidase was noted in multilaminate vesicles of the tegument. No evidence of significant endothelial changes, activation of coagulation or cellular response was associated with worms in situ. Endothelia in adjacent worms showed no increased permeability to horseradish peroxidase.