Effects of exogenous lipids on blood gas measurements.

OBJECTIVE: Numerous reports have appeared describing the effects of intravenous lipid administration on the pulmonary function of the critically ill patient. Our study was undertaken to determine whether the lipid content of an arterial blood gas specimen affects the measurement of arterial pH, PaO2, PaCO2, or arterial oxygen saturation. DESIGN: Prospective, in vitro controlled study. SETTING: Medical and cardiac intensive care units. PATIENTS: Critically ill patients undergoing clinically-directed blood gas sampling via indwelling arterial catheters. INTERVENTIONS: None. MEASUREMENTS: Arterial blood gas specimens were modified in vitro by dividing the sample and adding a known amount of lipid emulsion to half of the sample, resulting in a difference between the plasma triglyceride concentrations of the two halves. Two series of experiments were run: one series was run with a predicted plasma triglyceride difference of 400 mg/dL (4.5 mmol/L) between the two samples; the other series was run with a predicted plasma triglyceride difference of 800 mg/dL (9.0 mmol/L) between the two samples. Blood gas measurements were performed on each half of a sample, and the results were compared. Because some studies have only noted changes in patients with the adult respiratory distress syndrome (ARDS), samples from these patients were also analyzed as a separate group. RESULTS: No significant changes were found in arterial pH, PaO2, PaCO2, or arterial oxygen saturation between the two halves of the sample. With 95% confidence, differences as small as 1.5 torr (0.2 kPa) for PaO2 and PaCO2, 0.5% for arterial oxygen saturation, and 0.005 for pH, would have been detected. No differences were found in the ARDS subgroup. CONCLUSIONS: The addition of clinically relevant amounts of lipid to blood samples does not affect blood gas measurements. Any observed changes in blood gas values after lipid feeding are presumably due to products of lipid metabolism or alterations in pulmonary function.

Adenocarcinoma of the ciliary body pigment epithelium in a child.

Tumors arising from the pigment epithelium of the ciliary body are rare and most commonly occur in white adults. We describe a tumor that was clinically indistinguishable from a melanoma or medulloepithelioma occurring in a 7-year-old Japanese boy. Three months after initial evaluation, the eye was enucleated because of intractable intraocular pressure elevation and pain. On pathologic examination the tumor was found to fill approximately one third of the anterior chamber. Light microscopic and ultrastructural findings were consistent with an adenocarcinoma of the ciliary body pigment epithelium. To our knowledge, this is the youngest patient described with this tumor.

Detection of human papillomavirus DNA sequences in conjunctival papilloma.

Two histologically proven conjunctival papillomas (one from a 33-month-old boy and the other from a 28-year-old woman) were examined for the presence of papillomavirus by DNA molecular hybridization. The first case, a recurrent tumor known to be positive for papillomavirus structural antigen, demonstrated human papillomavirus DNA sequences that cross-hybridized to a human papillomavirus type 11 DNA probe. The second case, an initial tumor, which was negative for papillomavirus structural antigen, demonstrated no viral DNA sequences by hybridization.

In vitro malignant transformation of hamster retina by herpes simplex virus.

Hamster retina was infected in vitro with irradiated herpes simplex virus type 2. Cells underwent malignant transformation, and when injected subcutaneously into nude mice and hamsters, produced transferable tumors. Transformed cells were found to have HSV antigen as determined by indirect fluorescent staining. In addition, the undifferentiated transformed retinal cells possess neurosecretory granules and retinoic acid receptors and produce growth factor, features similar to those found in spontaneous human retinoblastoma. This is the first neoplasm of ocular tissues induced experimentally by herpes simplex virus (HSV).

Intraocular hemangiopericytoma.

A 40-year-old woman had an intraocular lesion consistent with a choroidal hemangioma. Xenon arc photocoagulation was applied to reduce subretinal fluid, and the lesion remained stationary until the patient's death eight years later. The lesion was composed of spindle-shaped and ovoid cells with numerous inconspicuous capillaries. The tumor cells were surrounded by reticulin-positive fibers. The diagnosis of hemangiopericytoma was confirmed by electron microscopy, which demonstrated proliferating pericytes associated with basal lamina. Although hemangiopericytomas are occasionally found in the orbit, to our knowledge this report is the first of an intraocular hemangiopericytoma. Because the pericyte is an integral component of the choroidal vasculature, the origin of this tumor in the choroid is not unexpected. The diagnosis of hemangiopericytoma should be considered when evaluating vascular choroidal lesions.

Papillomavirus in human conjunctival papillomas.

Forty-one human conjunctival papillomas were histopathologically examined for koilocytosis and papillomavirus common antigen with a peroxidase-antiperoxidase technique immunospecific for genus-specific papillomavirus antigen. Koilocytotic cells, typically found in other papillomavirus-induced tumors, were present in 24 of the 41 specimens. Two of the 41 specimens were positive for viral antigen. The positive reactions were intranuclear within the superficial layers of the epithelium.

Uveal tuberculosis.

Ocular tuberculosis should be considered in the differential diagnosis of panophthalmitis, uveitis, and intraocular neoplasms. We have presented 6 cases illustrating some of the clinical and pathological characteristics of two types of ocular involvement, acute tuberculous panophthalmitis and ciliary body tuberculoma. The former should be entertained when panophthalmitis or uveitis occur in debilitated patients with obvious systemic tuberculosis foci. Ciliary body tuberculoma should be suspected in relatively healthy individuals with a history of tuberculosis and an intraocular mass. The diagnosis is confirmed by positive cultures or the identification of the organism by acid-fast stains. Typical histopathology in the appropriate clinical setting is sufficient to start specific antituberculous therapy, which should be used in all cases.