Cutaneous malignant melanoma and oculodermal melanocytosis (nevus of Ota): report of a case and review of the literature.

A 29-year-old white man, with oculodermal melanocytosis, had a rapidly enlarging, erythematous, painful nodule over his left brow, within the nevus. The lesion was excised and diagnosed as a malignant melanoma. Systemic evaluation showed no evidence of distant disease. This is the tenth case reported of a cutaneous melanoma developing in a nevus of Ota. Melanoma arising in the choroid, brain, orbit, iris, ciliary body, or optic nerve in association with a nevus of Ota is well documented. Careful observation is necessary in patients with a nevus of Ota, particularly in white patients, in whom malignant degeneration seems to occur with a disproportionate frequency.

Thelazia californiensis conjunctival infestation.

There are few reports of Thelazia californiensis infestation in humans in the literature. The authors report the clinical and histopathologic features of two patients who presented with symptoms of a mild unilateral chronic conjunctivitis from infestation by this parasite. In each case, the symptoms resolved immediately after removal of the worms. These are the first two patients from the Rocky Mountain area to be described with an infection from this particular worm. T. californiensis should be included in the differential diagnosis of patients with chronic conjunctivitis following hiking or camping in the mountains or back-country.

Epikeratophakia to correct traumatic aphakia after penetrating keratoplasty.

A 19-year-old man with keratoconus sustained ocular trauma and became aphakic in his operated left eye 2 months after penetrating keratoplasty. Original corneal wound repair was performed without intraocular lens implantation. Attempts to correct his aphakia with a contact lens failed when the patient became intolerant to its use. As an alternative, the patient had elective epikeratophakia. A standard 8.5 mm lenticule was placed over existing corneal graft. This operation resulted in +12.25 diopters of correction and a best corrected visual acuity of 20/25 at 30 months postoperatively. There was no sign of abnormalities at the host cornea or the transplanted lenticule. This case indicates that epikeratophakia may be successfully performed over existing corneal grafts.

An altered T2 beta translocase of the glucose-6-phosphatase system in the membrane of the endoplasmic reticulum from livers of Ehrlich-ascites-tumour-bearing mice.

The inhibitory interactions of orthophosphate (P1) with the glucose-6-phosphatase system of intact microsomes derived from the livers of normal and Ehrlich-ascites-tumour-bearing mice reveal the appearance of a novel form of the T2 beta translocase component of the glucose-6-phosphatase system in tumour-stressed mice. Kinetic studies, with and without 20 mM P1, show a strictly classical competitive inhibition, with a K1,P1 of 4.2 mM, with disrupted microsomes from both control and tumour-bearing mouse liver. Inhibition was also observed with intact microsomes from livers of control mice, and contributions by both competitive and non-competitive components of inhibition were quantified by calculation of Kis,P1 and Kii,P1 values respectively. However, little inhibition was noted with intact microsomes from the livers of tumour-bearing mice. It is concluded that this novel form of T2 beta is less able to transport Pi, from the cytosol to the endoplasmic reticulum lumen, perhaps because of the tumour-related increased Km for Pi transport in this direction.

Lateral tarsorrhaphy and disposable soft contact lenses in aniridia patients after penetrating keratoplasty.

We report our experience with two patients with familial aniridia who underwent combined cataract extraction and penetrating keratoplasty. Persistent epithelial defects developed in all four eyes within 4 months. Combined lateral tarsorrhaphy and application of disposable soft contact lenses restored the integrity of the corneal epithelium, and 21 months after surgery, the grafts were clear and avascular.

Radial keratotomy in an elderly patient.

A 74-year-old male complained of poor vision and diplopia as a result of cataract extraction and intraocular lens implantation. On refraction, we found -6.25 diopters (D) of myopia in his right eye. The patient, dissatisfied with wearing contact lenses and spectacles to correct vision, opted to have refractive corneal surgery. We performed a four-incision radial keratotomy with a 4 mm clear zone. This resulted in a 3.75 D (-2.5 D residual myopia) reduction in myopia at two months of follow-up. Our results indicate that radial keratotomy may be useful for correcting unacceptable myopia in older patients.

The hepatic glucose-6-phosphatase system in Ehrlich-ascites-tumour-bearing mice.

To examine the effects of the presence of Ehrlich ascites tumours on both the catalytic unit and the substrate/product translocase components of the glucose-6-phosphatase system in vivo, we isolated microsomes from the livers of control and tumour-bearing mice. Samples were analysed immunochemically for the quantity of catalytic unit, stabilizing protein and translocases T2 and T3 proteins. In comparison experiments, a variety of kinetic studies were performed. The most striking findings in tumour-bearing mice were: a 2.5-fold increase in the quantity of translocase T2 protein; increases in the Km and Vmax. for glucose 6-phosphate phosphohydrolase; and a decrease in the Km value for carbamoyl phosphate (carbamoyl-P) of carbamoyl-P:glucose phosphotransferase, all with intact microsomes. The percentage latency at Vmax. decreased for PPi phosphohydrolase and for glucose 6-phosphate phosphohydrolase, but was unaffected for carbamoyl-P:glucose phosphotransferase. These observations support a tumour-related increase in translocase T2 capacity in vivo, as it transports Pi from the microsomal lumen to the medium and carbamoyl-P or PPi from the medium to the microsomal lumen.

Hysteretic behavior of the hepatic microsomal glucose-6-phosphatase system.

Carbamyl-P:glucose and PPi:glucose phosphotransferase, but not inorganic pyrophosphatase, activities of the hepatic microsomal glucose-6-phosphatase system demonstrate a time-dependent lag in product production with 1 mM phosphate substrate. Glucose-6-P phosphohydrolase shows a similar behavior with [glucose-6-P] less than or equal to 0.10 mM, but inorganic pyrophosphatase activity does not even at the 0.05 or 0.02 mM level. The hysteretic behavior is abolished when the structural integrity of the microsomes is destroyed by detergent treatment. Calculations indicate that an intramicrosomal glucose-6-P concentration of between 20 and 40 microM must be achieved, whether in response to exogenously added glucose-6-P or via intramicrosomal synthesis by carbamyl-P:glucose or PPi:glucose phosphotransferase activity, before the maximally active form of the enzyme system is achieved. It is suggested that translocase T1, the transport component of the glucose-6-phosphatase system specific for glucose-6-P, is the target for activation by these critical intramicrosomal concentrations of glucose-6-P.