Ultrastructure of axonal reaction in red nucleus of cat.

Described here are ultrastructural changes in neurons of feline red nucleus exhibiting axon reaction after unilateral rubropsinal tratotomy at the C-2 level and surviving 2 to 65 days. Ultrastructural alterations included neurofilamentous hyperplasia; proliferation of smooth ER; temporary disappearance of organized granular ER with partial substitution by haphazardly arranged, broad cisternal profiles; loss of rosette ribosomes and occurrence of single ribonucleoprotein granules or an intercisternal amorphous density; increased numbers of subsurface cisterns and allied structures, often disposed in stacks; vesiculation and vacuolation of Golgi cisternae; prevalence of autophagic bodies derived in part from Golgi complexes; probable mitochondrial hyperplasia and various qualitative changes in these organelles; an increase in lipofuscin. Dendritic changes paralleled those of perikarya save that proliferation of subsurface cisterns and autophagic bodies was absent. Abnormalities of myelinated axons and boutons occurred and may have originated from retrograde degeneration of cortical neurons induced by lateral funiculotomy. Some perikarya were devoid of axosomatic boutons. Ultrastructural changes varied with the length of postoperative survival and were, at least partly, reversible. Chromatolysis was detectable light microscopically before ultrastructural abnormality appeared. The bearing of transneuronal mechanisms on axon reaction of central neurons and the protective effect of section of axons beyond the site of origin of collaterals are discussed.

Localization and regulation of corticotropin receptor expression in the midgestation human fetal adrenal cortex: implications for in utero homeostasis.

Developmental changes in the responsiveness of the fetal adrenals to corticotropin (ACTH) play an important role in the regulation of the fetal hypothalamic-pituitary-adrenal axis. Responsiveness of adrenal cortical cells to ACTH is dependent on the extent of ACTH receptor expression. Therefore, we examined the localization and regulation of ACTH receptor expression in the midgestation (16-24 weeks) human fetal adrenal cortex. In situ hybridization analysis was used to localize messenger RNA (mRNA) encoding the ACTH receptor in sections of human fetal adrenal glands. Messenger RNA encoding the ACTH receptor was localized in cells from all cortical zones; abundance was higher in definitive zone than in fetal zone cells and was least abundant in the more central portions of the cortex. Regulation of ACTH receptor expression was studied using Northern blot analysis of total RNA extracted from primary cultures of fetal and definitive zone cells. Two major (1.5 and 3.5 kilobases) and, upon stimulation with ACTH, 3 minor (4.0, 6.0 and 10.0 kb) ACTH receptor mRNA transcripts were detected in RNA from fetal and definitive zone cells. In both cell types, ACTH-(1-24) increased the abundance of mRNA encoding the ACTH receptor 10- to 20-fold compared with untreated cells. The effects of ACTH-(1-24) on ACTH receptor expression in fetal zone cells were time- and dose-dependent. The ED50 for the stimulation of ACTH receptor expression by ACTH-(1-24) was 1-10 pM, and maximal response to 0.1 nm ACTH-(1-24) was detected after 12-16 h. Eight-bromoadenosine cAMP and forskolin also stimulated ACTH receptor expression in fetal zone cells and closely mimicked the effects of ACTH-(1-24). In contrast, stimulation of protein kinase C with 12-O-tetradecanoyl phorbol 13-acetate had no effect on ACTH receptor expression. Changes in ACTH receptor expression in response to ACTH-(1-24), cAMP and forskolin were paralleled by changes in expression of the P450 cholesterol side chain cleavage (P450scc) enzyme. These data demonstrate that expression of the ACTH receptor by the human fetal adrenal cortex is up-regulated by its own ligand and that this effect is mediated by a cAMP-dependent mechanism. In addition, the coordinate stimulation of ACTH receptor and P450scc expression by ACTH indicates that the gene for the ACTH receptor is one of a specific cohort of genes regulated by ACTH that are required to facilitate fetal adrenal cortical response to ACTH. ACTH regulation of its own receptor may represent a mechanism by which fetal adrenal responsiveness to ACTH is maintained and possibly enhanced during fetal development.

Second order auditory pathways in the chimpanzee.

Substantial portions of the dorsal, and almost the entire posteroventral and anteroventral (Av) cochlear nuclei were aspirated unilaterally in a chimpanzee. Axonal degeneration was studied by the Fink-Heimer method. The greatest amount of degeneration was followed medially from the region of Av into the lateral part of the trapezoid body. Degeneration also coursed around the superior surface of the restiform body and was traced into the dorsal and intermediate acoustic striae. Within the superior olivary complex, degeneration was distributed to: the ipsilateral lateral superior olive; laterally and medially oriented dendrites of the ipsilateral and contralateral medial superior olivary nuclei respectively (some perisomatic degeneration also was present bilaterally); the contralateral medial trapezoid nucleus; retro-olivary and preolivary cell groups bilaterally. Abundant degeneration passed into the contralateral lateral lemniscus and was distributed largely to its ventral nucleus. The contralateral central nucleus of the inferior colliculus was a major site of termination of ascending second order auditory fibers. The caudal tip of the ipsilateral ventral nucleus of the lateral lemniscus received abundant degeneration, but this diminished rostrally. The ipsilateral inferior colliculus contained a moderate amount of degeneration. A fair number of degenerated second order auditory fibers ascended in the contralateral brachium of the inferior colliculus and were distributed both to the principle and magnocellular divisions of the medial geniculate body. This pathway appears to represent a phylogenetic advance in the brain of the great ape.

Agents for the treatment of brain injury. 1. (Aryloxy)alkanoic acids.

Blunt and ischemic injuries of the brain have been shown to result in swelling that is predominantly limited to a single cell type, the astrocyte, within the complex cellular mosiac of cerebral gray matter. Evaluation of various diuretic (aryloxy)acetic acids in vitro using incubating cat brain slices and primary astrocyte cultures identified compounds with marked ability to inhibit brain tissue swelling. Some of the compounds significantly reduced the mortality and morbidity following acceleration/deceleration brain injury in anesthesized cats. A variety of (indanyloxy)alkanoic acids were synthesized which were analogous to the dually active (indanyloxy)acetic acids. Some of the 4-(indanyloxy)butanoic acids were found to be devoid of diuretic activity but to possess equal or greater activity than the dually active compounds in the in vitro and in vivo brain assays. Selected examples from both the (indanyloxy)acetic and 4-(indanyloxy)butanoic acid series showed marked chiral effects, with one enantiomer generally exhibiting a much greater activity than the other. A clinical study of severely head-injured patients treated with ethacrynic acid demonstrated a significantly improved outcome when compared to controls. These data suggest a clinical advantage for the nondiuretic (aryloxy)alkanoic acids which possess in vitro and in vivo activities in the cat brain assays that are comparable or superior to dually active compounds.

A system for long-term corneal perfusion.

Seventy-two human corneas were maintained in a perfusion system at 37 degrees C and 18 mm Hg intracameral pressure for 1 to 3 weeks. Corneal thickness, which was initially greater than normal because the enucleated eyes were kept at 4 degrees C before excision of the corneas, decreased slowly during the period of incubation. Endothelial removal or perfusion with ouabain (10(-4) M) induced irreversible stromal swelling. Cooling to 4 degrees C for 8 hr during perfusion caused stromal swelling that disappeared after rewarming to 37 degrees C; less stromal swelling occurred with cooling after 3 weeks of perfusion than after 3 days. No enlargement of central endothelial cells was noted in most corneas by serial specular microscopy. Electron microscopy demonstrated reversal of postmortem changes and maintenance of normal intracellular ultrastructure for 3 weeks. This system for long-term corneal perfusion will allow controlled studies of the effects of new methods of corneal preservation and other perturbations upon the corneal endothelium in situ.

Central corneal endothelial cell changes over a ten-year period.

PURPOSE: To obtain longitudinal data to estimate long-term morphometric changes in normal human corneal endothelia. METHODS: Ten years after an initial study, the authors rephotographed the central corneal endothelium of 52 normal subjects with the same contact specular microscope. The findings for the 10 subjects younger than 18 years of age at the initial examination were considered separately. For the remaining 42 adult subjects, the time between examinations averaged 10.6 +/- 0.2 years (range, 10.1 to 11 years). At the recent examination, these subjects' ages averaged 59.5 +/- 16.8 years (range, 30 to 84 years). Outlines of 100 cells for each cornea were digitized. RESULTS: For the 42 adult subjects, the mean endothelial cell density decreased during the 10.6-year interval from 2715 +/- 301 cells/mm2 to 2539 +/- 284 cells/mm2 (P < 0.001). The calculated exponential cell loss rate over this interval was 0.6% +/- 0.5% per year. There was no statistically significant correlation between cell loss rate and age. During the 10.6-year interval, the coefficient of variation of cell area increased from 0.26 +/- 0.05 to 0.29 +/- 0.06 (P < 0.001), and the percentage of hexagonal cells decreased from 67% +/- 8% to 64% +/- 6% (P = 0.003). For the 10 subjects 5 to 15 years of age at the initial examination, the exponential cell loss rate was 1.1% +/- 0.8% per year. CONCLUSIONS: Human central endothelial cell density decreases at an average rate of approximately 0.6% per year in normal corneas throughout adult life, with gradual increases in polymegethism and pleomorphism.

The morphology and function of healing cat corneal endothelium.

We mechanically damaged the entire corneal endothelium of one eye of each of ten cats and then examined both eyes by fluorophotometry and specular microscopy for 5 months. Six weeks after damage, when the corneas had cleared sufficiently to make accurate measurements, the mean endothelial permeability to carboxyfluorescein was increased 11% (P = 0.02) and the mean central corneal thickness was increased 11% (P = 0.05) in the damaged eyes. The mean endothelial pump rate was decreased 29% (P = 0.05), indicating that the increase in permeability was insufficient to explain the increase in thickness. The permeability returned to normal by 3 months and the pump rate by 5 months. Six weeks after damage, the mean endothelial cell size was increased 89% (P less than 0.01), the mean coefficient of variation of cell size was increased 200% (P less than 0.01), and the mean percentage of hexagonal cells was decreased 34% (P less than 0.01). By 5 months, the mean cell size had changed very little, and none of the three morphologic measurements had returned to normal. As in rabbits, the endothelial barrier in cats recovers before the pump after wounding. Unlike in rabbits, functional recovery in cats requires at least several months. Such prolonged functional recovery after endothelial trauma might also be expected in humans who, like cats and unlike rabbits, have little capacity for endothelial mitosis during healing.

Automated quantification of keratocyte density by using confocal microscopy in vivo.

PURPOSE: To compare keratocyte density determined by using confocal microscopy with keratocyte density determined in the same corneas by histology. METHODS: Digital en face images of central corneas were recorded three times by using confocal microscopy in vivo in six New Zealand White rabbits. Bright objects (keratocyte nuclei) in the images were automatically identified by using a custom algorithm to estimate total and regional stromal keratocyte densities. The corneas were then excised, fixed, and sectioned in a sagittal plane for histology. Keratocyte nuclei were manually counted from digitized images of 50 histologic sections per cornea. Total and regional keratocyte densities were estimated from the histologic sections by using stereologic methods based on nuclei per unit area, mean nuclear diameter, and section thickness. Histologic cell densities were corrected for tissue shrinkage. RESULTS: By confocal microscopy, total keratocyte density was 39,000 +/- 1,200 cells/mm3 (mean +/- SE; n = 6); cell density was 47,100 +/- 1,300 cells/mm3 in the anterior stroma and decreased to 27,900 +/- 2,700 cells/mm3 in the posterior stroma (P = 0.004). Analysis of the three separate confocal images of each cornea produced repeatable total cell densities (mean coefficient of variation = 0.035). By histology, total keratocyte density was 37,800 +/- 1,100 cells/mm3, not significantly different from that estimated by confocal microscopy (P = 0.43); anterior cell density was 48,300 +/- 900 cells/mm3 and decreased to 29,400 +/- 900 cells/mm3 posteriorly (P < 0.001). CONCLUSIONS: Rabbit keratocyte density estimated by automated analysis of confocal microscopy images in vivo is repeatable and agrees with keratocyte density estimated from histologic sections.

Long-term observation of morphologic and functional features of cat corneal endothelium after wounding.

PURPOSE: (1) To test the hypothesis that corneas with enlarged endothelial cells (and thus less intercellular space) have decreased endothelial permeability to small polar solutes. (2) To measure corneal endothelial ouabain binding (Na+/K+ ATPase "pump site" density) and Descemet's membrane production after endothelial wounding. METHODS: Bilateral specular microscopy and anterior segment fluorophotometry were performed at 2-month intervals for 1 year in ten cats after mechanically damaging the corneal endothelium in one eye of each. The measurements were repeated at 2 years in four cats and at 3 years in two cats. Eighteen months after wounding, endothelial ouabain binding was measured in both eyes of six cats. Transmission electron micrographs of Descemet's membrane were analyzed in both eyes of six cats at 18 months, two cats at 2 years, and two cats at 3 years after wounding. RESULTS: From 6 to 12 months after wounding, the endothelial permeability to carboxyfluorescein was significantly decreased (P < 0.05), and the mean endothelial cell size was significantly increased (P < 0.001) in the damaged eyes. The enlarged endothelial cells persisted in the few cats observed 2 and 3 years after wounding. There was no significant difference in endothelial ouabain binding between the damaged and control corneas in six cats tested 18 months after wounding. On subsequent histologic examination, a layer of abnormal Descemet's membrane was present in all ten wounded eyes, with additional normal Descemet's membrane posterior to it, between the abnormal layer and the endothelial cells. CONCLUSIONS: The results are consistent with the hypothesis that corneal endothelial permeability to small polar solutes varies directly with the amount of intercellular space available for diffusion across the monolayer. The results also confirm clinical reports of decreased endothelial permeability in corneas with enlarged endothelial cells. In histopathologic specimens, a layer of abnormal Descemet's membrane can be a historical marker for a period of endothelial damage and corneal decompensation.

The contralateral corneal endothelium in the iridocorneal endothelial syndrome.

OBJECTIVE: To evaluate the corneal endothelial morphometric measures of the contralateral, clinically uninvolved eye of patients with the iridocorneal endothelial (ICE) syndrome. DESIGN: A retrospective review of the specular microscopic photographs of the contralateral corneal endothelium of all patients with ICE syndrome seen at Mayo Clinic, Rochester, Minn. SETTING: Ophthalmology department, Mayo Clinic. PARTICIPANTS: Twenty-eight patients with unilateral ICE syndrome who had bilateral endothelial photographs (ICE group) and 28 normal, age-matched control subjects (control group). MAIN OUTCOME MEASURES: Percentage of hexagonal cells, coefficient of variation of cell area, and endothelial cell density. METHODS: For each patient and control, 100 endothelial cells were digitized from projected endothelial photomicrographs of the central corneas in the uninvolved eyes. RESULTS: A statistically significant decrease was noted in the mean percentage of hexagonal cells (ICE, 62%; control, 69%; P = .002), and an increase was noted in the mean coefficient of variation of cell area (ICE, 0.28; control, 0.25; P = .02) in the patients with ICE syndrome compared with normal, age-matched controls. The mean endothelial cell density did not differ significantly between the 2 groups (ICE, 2588; control, 2759; P = .10). CONCLUSION: Our data suggest that the clinically uninvolved, contralateral eyes in patients with ICE syndrome have subclinical endothelial abnormalities as evidenced by a relatively low percentage of hexagonal cells and a relatively high coefficient of variation of cell area.

Opioid but not nonopioid stress-induced analgesia is enhanced following prenatal exposure to ethanol.

Two neurochemically distinct forms of stress-induced analgesia were examined in adult rats following prenatal ethanol exposure. Rats were exposed to ethanol during the last 2 weeks of gestation through a liquid diet presented to the dams. Analgesia testing was conducted when the offspring were 150-210 days of age. Two forms of footshock stress were administered; one that resulted in a naloxone-sensitive (opioid-mediated) analgesia and one that resulted in a naloxone-insensitive (nonopioid) form of analgesia. Rats prenatally exposed to ethanol demonstrated significantly enhanced opioid-mediated analgesia, but unaltered nonopioid analgesia compared to controls. These results confirm previous findings that prenatal exposure to ethanol leads to long-term alterations in responding to some, but not all forms of stress. The possibility that prenatal exposure to ethanol leads to perturbations in the endogenous opioid systems is discussed.

Apparent involvement of opioid peptides in stress-induced enhancement of tumor growth.

Exposure to stress has been associated with alterations in both immune function and tumor development in man and laboratory animals. In the present study, we investigated the effect of a particular type of inescapable footshock stress, known to cause an opioid mediated form of analgesia, on survival time of female Fischer 344 rats injected with a mammary ascites tumor. Rats subjected to inescapable footshock manifested an enhanced tumor growth indicated by a decreased survival time and decreased percent survival. This tumor enhancing effect of stress was prevented by the opiate antagonist, naltrexone, suggesting a role for endogenous opioid peptides in this process. In the absence of stress, naltrexone did not affect tumor growth.

The effects of temperature and inhibitors on HCO3-stimulated swelling and ion uptake of monkey cerebral cortex.

In the presence of high concentrations of K+, additions of HCO3- as low as 0.35 mM caused a 23% increase in swelling, and concomitant increases in the chloride content of incubating monkey cerebrocortical slices. The uptake of chloride was accompanied by increased uptake of sodium and was highly temperature dependent, showing a marked activation at approximately 30 degrees C. A similar temperature activation was also found for a Mg2+-dependent, HCO3-stimulated ATPase activity in monkey cerebral cortex, consistent with a possible role for this enzyme in the K+ and HCO3-dependent swelling process and its associated ion movements. K+-dependent, HCO3-stimulated cerebrocortical tissue swelling with uptake of Na+ and Cl- was inhibited by acetazolamide indicating that carbonic anhydrase was also involved. The addition of ouabain also inhibited swelling and K+ and Cl- uptake at low concentrations, but led to increased swelling at higher concentrations ( greater than 10 mum). A similar biphasic effect on swelling was also seen following addition of ethacrynic acid.

Banding of rubro-olivary terminations in the principal inferior olivary nucleus of the chimpanzee.

An electrolytic lesion centered just dorsal to, and grazing the superior surface of, the rostral red nucleus (RNr) was produced stereotactically in a single chimpanzee. Perikarya of the ipsilateral RNr exhibited retrograde cell changes, demonstrating interruption of its efferent fibers. The degenerated rubro-olivary tract was followed in silver impregnated material to the ipsilateral compact part of the pedunculopontine nucleus, pontine reticular formation and inferior olivary complex. Within the inferior olivary complex, terminations were banded and restricted to the principal subnucleus.

Morphine analgesia is potentiated in adult rats prenatally exposed to ethanol.

Exposure to inescapable, intermittent footshock elicits an opioid-mediated stress-induced analgesia in rats. We have previously shown that this response is markedly potentiated in adult rats, prenatally exposed to ethanol. To further investigate our hypothesis that endogenous opioid pain-inhibitory systems are modified by prenatal ethanol exposure, we have measured the analgesic response to morphine, in vitro brain opiate receptor binding characteristics, and occupation of brain opiate receptors following systemic administration of morphine. Compared to controls, rats prenatally exposed to ethanol had significantly enhanced morphine analgesia. This enhancement, however, does not appear attributable to changes in number or affinity of mu or delta opiate receptors, or to altered occupation of receptors by morphine.

Incorporation of tritiated leucine by axotomized rubral neurons.

Fourteen kittens, 7--10 weeks of age, were injected with [3H]leucine 0.5--24 h before sacrifice 1--30 days after unilateral high cervical rubrospinal tractotomy. Histoautoradiographs of the red nuclei were prepared and counterstained with thionin. Axon reaction, evident histologically 24 h after surgery, was manifested by central chromatolysis or diffuse cytoplasmic chromophobia. Partial reversion toward a normal cytologic appearance was apparent 10--30 days postoperatively. Nucleolar and nuclear shrinkage and cytoplasmic atrophy were conspicuous accompaniments of axon reaction in rubral neurons. Expressed per cell the radioactivity of axotomized rubral nerve cells was consistently less than controls in animals surviving operation from 5 to 30 days. The data indicate that axon reaction in red nucleus is regressive in character and early associated with diminished protein synthesis. The frequently regressive nature of axon reaction in intrinsic neurons, such as those of red nucleus, probably is important in accounting for failure of regeneration of many mammalian CNS fiber tracts after injury.

Suppression of follicular phase pituitary-gonadal function by a potent new gonadotropin-releasing hormone antagonist with reduced histamine-releasing properties (ganirelix).

OBJECTIVE: To determine if daily subcutaneous doses of ganirelix will suppress and maintain E2 < or = 30 pg/mL (conversion factor to SI unit, 3.671), the serum profiles of LH and FSH during and after cessation of treatment, the time-course of the resumption of normal ovarian function after ganirelix cessation, and to identify side effects of daily treatment. DESIGN: Open-label nonrandomized clinical study. SETTING: Normal human volunteers in an academic research center. PATIENTS: Women 21 to 45 years of age, with documented ovulatory menstrual cycles. INTERVENTIONS: Ganirelix was administered subcutaneously daily for 8 days. Blood samples were obtained during dosing as well as before and after cessation of dosing. MAIN OUTCOME MEASURES: Changes in serum E2, LH, FSH, P, and ganirelix. RESULTS: Ganirelix treatment rapidly decreased serum levels of gonadotropins and E2 after both 1 and 2 mg administration. Twenty-four hours after the first dose of ganirelix, E2 decreased from a mean +/- SEM of 50 +/- 8 and 67 +/- 11 pg/mL at baseline to 25 +/- 4 and 20 +/- 3 in the 1 mg and 2 mg groups, respectively. Estradiol remained suppressed (mean levels < 26 pg/mL) on all subsequent 7 days of ganirelix dosing in both groups. After the final dose of ganirelix, there was a rapid return of ovarian function in all volunteers. All women had P levels indicative of ovulation in the subsequent cycle, and the mean number of days from the final ganirelix dose to the next menses was 25.8 +/- 2.1 and 27.3 +/- 1.6 in the 1 and 2 mg groups, respectively. CONCLUSIONS: Daily ganirelix administration is effective in suppressing the pituitary-gonadal axis and has a side effect profile that should be well tolerated.

Dose-related suppression of serum luteinizing hormone in women by a potent new gonadotropin-releasing hormone antagonist (Ganirelix) administered by intranasal spray.

OBJECTIVE: To determine if the GnRH antagonist (GnRH-a) Ganirelix (Syntex Research, Palo Alto, CA), administered by intranasal (IN) spray to normal women, is absorbed into the systemic circulation and suppresses LH secretion. DESIGN: A single center, open label, nonrandomized, dose-escalation study. SETTING: Academic research environment. PATIENT(S): Normal female volunteers ages 23 to 43 years. INTERVENTION(S): Ganirelix was administered as a single dose by IN spray. The administered doses and the number of women receiving each of them were 0.1 mg (n = 1), 0.3 mg (n = 1), 1 mg (n = 2), 3 mg (n = 5), and 6 mg (n = 5). Blood samples were collected from -15 minutes to 24 hours after dosing. MAIN OUTCOME MEASURE(S): Serum concentrations of Ganirelix and LH. RESULT(S): Ganirelix was absorbed rapidly. The mean time to maximal serum levels in the 3- and 6-mg groups was 0.67 and 0.53 hour, respectively. Mean serum LH levels were suppressed by > or = 35% relative to baseline from 2 to 12 hours after dosing in both groups. The mean maximal percent decrease in serum LH was -62% (at 8 hours after dosing) and -74% (at 6 hours after dosing) in the 3- and 6-mg groups, respectively. CONCLUSION(S): Single dose IN administration of 3 or 6 mg of Ganirelix suppressed serum LH levels in women, further enhancing the potential clinical utility of this potent GnRH-a. This is the first clinical report of a GnRH-a reducing the secretion of a pituitary gonadotropin when administered by an IN delivery system. Based on the duration and extent of LH suppression observed in this study, Ganirelix, administered by twice daily IN spray, may be effective for the treatment of gonadal hormone-dependent disorders in women.

Corneal endothelium five years after transplantation.

We asked the recipients of 500 consecutive corneal transplants to return for examination and endothelial photography at two months and at one, three, and five years postoperatively. Thirty-six regrafts and 70 fellow eyes of bilateral cases were excluded, leaving 394 eyes for analysis. We also recorded episodes of graft rejection and failure. In 129 grafts in patients who returned at each postoperative interval and had no rejection episodes, the mean endothelial cell density continued to decrease 7.8% per year from three years to five years after keratoplasty, compared with approximately 0.5% per year in unoperated-on normal corneas. The mean cell loss compared with the preoperative examination was 58.9% five years after keratoplasty. The percentage of hexagonal cells did not return to preoperative levels by five years after keratoplasty, suggesting that the endothelium continued to be unstable. The mean corneal thickness increased significantly with time. The Kaplan-Meier rates of rejection episodes and failure were 19% and 17%, respectively, five years after keratoplasty. Eyes with posterior chamber lens implants lost more endothelial cells by five years after keratoplasty than did eyes with open-looped anterior chamber lens implants. Low endothelial cell densities were statistically significantly associated with increased corneal thickness and with an increased risk of subsequent failure. The central endothelial cells of successful corneal transplants five years after keratoplasty form an unstable monolayer with continued accelerated loss of cells and abnormal cellular morphologic features. This process results in fewer endothelial cells remaining on the central graft with an associated increase in stromal swelling and graft failure.

Specular microscopy before and after enucleation of live donor eyes.

PURPOSE: To compare the results of specular microscopic examination of corneal endothelium before and after enucleation of eyes from live donors. METHODS: Endothelial cell density (ECD), coefficient of variation of cell area (CV), and percent hexagonal cells were compared for 34 cornea donors before enucleation of their eyes and after excision of the corneoscleral rims and placement in preservative media. RESULTS: There was no statistically significant difference in ECD, CV, or percent six-sided cells after enucleation. The pre-enucleation and post-enucleation ECD measurements were significantly correlated (rs = .85, P < .0001). Mean percentage change in ECD was -0.7% +/- 6.0%. CONCLUSIONS: There was no significant difference in ECD, CV, or percent six-sided cells between measurements taken from the epithelial side in vivo and those taken of the same corneas from the endothelial side in vitro after enucleation and corneoscleral rim excision. These findings suggest that it is reasonable to compare postkeratoplasty clinical measurements with those of the donor corneas taken in the eye bank.