Age-related decrease in human corneal γ-glutamyltranspeptidase activity.

PURPOSE: To investigate age-related effects on human corneal γ-glutamyltranspeptidase (GGT) (ectoenzyme important to maintaining corneal hydration and antioxidant potential via glutathione recapture). METHODS: Age-related differences between total, endothelial, and epithelial GGT activity and endothelial cell density were determined for corneas from 29 donors (mean age, 53 ± 17 years; age range, 13-83 years). GGT activity was determined using a standard colorimetric assay based on the transpeptidation reaction. Corneal GGT localization and expression was determined by immunohistochemistry. RESULTS: Total corneal, endothelial, and epithelial GGT activities in the young (<50 years) donor corneas were 37% (P = 0.02), 44% (P = 0.001), and 36% (P = 0.06) higher, respectively, than in the senior (≥50 years) corneas. The age-related rates of decline for GGT activity were 1.0 unit per year for total cornea, 0.4 to 0.5 unit per year for endothelium, and 0.3 to 0.4 unit per year for epithelium. Notably, endothelial cell density in the young corneas was 14% (P = 0.001) higher than in the senior corneas declining about 100 cells per square millimeter per decade (0.3% per year). GGT activity per 10 endothelial cells decreased at about 0.2 units per year and GGT activity per 10 endothelial cells in the young corneas was 41% higher (P = 0.01) than in the senior corneas. Fewer immunoreactive GGT-positive epithelial cells were detected in senior cornea. CONCLUSION: The age-related loss of human corneal GGT activity was associated with reductions in endothelial and epithelial GGT activity, being because of reduced number of GGT-positive endothelial and epithelial cells and reduced GGT activity per endothelial cell.

Orbital sporadic Burkitt lymphoma in an adult diabetic African American female and a review of adult orbital cases.

A case of sporadic Burkitt lymphoma (sBL) presenting with jaw and lid involvement in a diabetic adult African American female and a review of adult orbital Burkitt lymphoma cases are presented. Lid edema, visual loss, ophthalmoparesis, proptosis, and sinusitis progressed over 4 weeks despite antibiotic and steroid treatment. Upper lid biopsy histopathological evaluation and immunophenotyping revealed a homogenous mass of atypical CD10 and CD20-negative B-cells and tingible body macrophages yielding a "starry sky" appearance. Cytogenetic analysis detected a minor variant c-MYC translocation, but no Epstein-Barr virus RNA. Detection of multiple lesions prompted a diagnosis of stage IV disease that totally regressed following radiation and chemotherapy. Review results of the six adult orbital sBL cases support a poor prognosis and a heightened suspicion of variant CD10, CD20 and BCL6 positive sBL in adults presenting with jaw pain and rapidly progressive orbital symptoms, particularly in female, African American, and diabetic patients.

Basal cell cystadenoma of the lacrimal gland: diagnostic pitfalls of a basaloid pattern in lacrimal tumours.

An 85-year-old male experienced a painless swelling along the left lateral orbit for one year. A computed tomography scan demonstrated a cystic mass in the orbit adjacent to the lacrimal gland. There was a concern for malignancy considering the large size and the patient's age, so the tumour was excised. Histopathology of the tumour showed nests with basaloid patterns, but a definitive diagnosis was not rendered. The uncertainty of tissue diagnosis coupled with the basaloid pattern, which carries a grim prognosis in some salivary gland tumours, led us to refer this case to an authority on lacrimal gland pathology, who suggested that this tumour be called a basal cell cystadenoma. To the best of our knowledge, a basal cell cystadenoma of the lacrimal gland has not been reported in the literature. We present histopathological features that distinguish this tumour from malignant tumours with a basaloid pattern. We also discuss the management differences associated with basaloid patterns in lacrimal tumours.

Glutamate, excitatory amino acid transporters, Xc- antiporter, glutamine synthetase, and gamma-glutamyltranspeptidase in human corneal epithelium.

PURPOSE: The viability and functions of the corneal epithelium are dependent in large measure on the active uptake of nutrients, growth factors, and amino acids from stroma and tear. The present study presents the cellular distribution(s) of glutamate, the Na(+)-dependent glutamate/aspartate transporters (excitatory amino acid transporters; EAAT1-5), Na(+)-independent glutamate/cystine exchanger (Xc(-) antiporter) subunits (xCT light chain and 4F2hc heavy chain), glutamine synthetase (GS), and gamma-glutamyltranspeptidase (GGT) in human corneal epithelium. METHODS: Glutamate, EAAT1-5, xCT/4F2hc, GS, and GGT immunoreactive proteins were detected by immunofluorescence microscopy. Human corneal GGT activity was quantified using a standard colorimetric assay. RESULTS: Glutamate, EAAT3>2>1, xCT/4F2hc, and GGT proteins were detected in the columnar and wing cells. Glutamate was reduced or absent in the EAAT negative, Xc(-) antiporter, and GS positive outer wing cell and flat superficial epithelial cell layers. All EAATs (EAAT3>4/5>1/2), xCT/4F2hc, GS, and GGT were detected in flat superficial epithelial cell layer. CONCLUSIONS: The localization of glutamate, multiple EAATs, Xc(-) antiporter proteins, and GGT to columnar and superficial epithelial cell layers suggests uptake of glutamate and cystine from the stroma and tear and supports their importance in regulation of glutamate/cystine and glutathione (GSH; a tripeptide of glutamate, cystine, and glycine) in the human cornea epithelium. In addition, the low glutamate levels in outer wing and flat superficial epithelial cells positive for Xc(-) antiporter and GS are consistent with exchange of glutamate by Xc(-) antiporter for extracellular cystine utilized in GSH synthesis and support coupling of ammonia detoxification with glutamate degradation by GS.

Orbital metastasis of keratinizing squamous cell cervical carcinoma with giant cells. A case report.

A case of orbital metastasis of cervical keratinizing squamous cell carcinoma is presented. The patient, in remission from primary cervical and ovarian cancers, presented with complaints of left eye ptosis and pain. Examination revealed the presence of a moderately tender mass along the left supra-temporal orbital rim and downward displacement of the left globe. Computed tomography revealed a poorly circumscribed mass with superior lateral wall bone loss. Excised tissue contained invasive, poorly differentiated nests of pan keratin and epithelial membrane antigen-positive squamous cells with numerous pleomorphic multinucleated giant cells. Multiple treatment regimes were unsuccessful, and the patient expired due to disease complications after 3 months.

Intracameral toxicity of bacterial components muramyl dipeptide and staurosporine: ciliary cyst formation, epithelial cell apoptosis and necrosis.

The uveitogenic bacterial cell wall component muramyl dipeptide (MDP) is apoptogenic in rabbit kidney cells. The purpose of this investigation was to assess the cytotoxic activity of MDP and staurosporine (STSP; induces cultured corneal and lens cells apoptosis) in rabbit ciliary body tissue. Anterior uveitis was determined by clinical symptoms and increased aqueous humor (AH) protein. Ciliary body tissue was assessed for histological changes, caspase-3 activity, dye uptake, distribution of immunoreactive caspase-3 and DNA ladders at 4 and 6 hours postinjection. Increases in caspase-3 activity, APOPercentage dye uptake, and localization of immunoreactive caspase-3 in ciliary epithelial cells were associated with ciliary cysts of detached nonpigmented epithelial (NPE) cells, as well as apoptotic and necrotic DNA ladders in ciliary body tissues from eyes injected with MDP and/or STSP. The results suggest that intracameral injection of the bacterial components MDP and STSP can induce acute endophthalmic changes in uveal tissue including formation of ciliary body, NPE and pigmented epithelial (PE) cell apoptosis, and ciliary body tissue necrosis.