Aural tuberculosis.

Since the advent of antituberculous therapy, tuberculosis of the ear has decreased in incidence; but of late, cases of both pulmonary and otologic tuberculosis are on the rise. In addition, the treatment of aural tuberculosis is now more difficult due to resistance to one or more of the routinely used antituberculous pharmacotherapeutic agents. Urban areas and selected populations have been particularly endangered by the re-emergence of this disease. In light of this developing situation, three cases of aural tuberculous infections are presented. Typical and atypical presentations of the disease, including history, signs, symptoms, and radiographic findings are discussed, as are treatment options. The importance of aural tuberculosis as part of the general increase in incidence and resistance of the disease is examined.

Vertical nitrate fluxes in the oligotrophic ocean.

The vertical flux of nitrate across the thermocline in the upper ocean imposes a rigorous constraint on the rate of export of organic carbon from the surface layer of the sea. This export is the primary means by which the oceans can serve as a sink for atmospheric carbon dioxide. For the oligotrophic open ocean regions, which make up more than 75% of the world's ocean, the rate of export is currently uncertain by an order of magnitude. For most of the year, the vertical flux of nitrate is that due to vertical turbulent transport of deep water rich in nitrate into the relatively impoverished surface layer. Direct measurements of rates of turbulent kinetic energy dissipation, coupled with highly resolved vertical profiles of nitrate and density in the oligotrophic eastern Atlantic showed that the rate of transport, averaged over 2 weeks, was 0.14 (0.002 to 0.89, 95% confidence interval) millimole of nitrate per square meter per day and was statistically no different from the integrated rate of nitrate uptake as measured by incorporation of (15)N-labeled nitrate. The stoichiometrically equivalent loss of carbon from the upper ocean, which is the relevant quantity for the carbon dioxide and climate question, is then fixed at 0.90 (0.01 to 5.70) millimole of carbon per square meter per day. These rates are much lower than recent estimates based on in situ changes in oxygen over annual scales; they are consistent with a biologically unproductive oligotrophic ocean.

Caruncular dacryops with extruded secretory globoid bodies.

A 52-year-old black man evaluated for a left cataract following an iritis was incidentally noted to have a vascularized, firm, inflammatory-appearing left caruncular mass. Removal of the cataract and of the left caruncular mass led to the discovery that the latter was composed of dilated channels containing secretory globoid bodies; the cyst wall was composed of a double layer of cuboidal epithelium, occasionally displaying apical cytoplasmic snouts. Lobules of lacrimal gland tissue were found in intimate association with the cystic spaces in multiple foci. The secretory globoid bodies had ruptured from the cystic cavity into the connective tissue of the caruncle, where a multinucleated foreign body-type granulomatous response had been elicited. This spontaneous rupture and the ensuing inflammation accounted for the inflammatory character of the lesion on clinical examination. The authors believe that secretory globoid bodies are a distinctive feature of dacryops, which normally occurs in the major lacrimal gland. When dacryops occurs in a minor lacrimal gland of the caruncle or fornices (glands of Krause or Wolfring), the presence of secretory globoid bodies may help to distinguish dacryops in these unusual locations from small conjunctival inclusion cysts, which sometimes have calcareous inclusions but lack the myriad spherical secretory bodies of dacryops.

Mucoepidermoid carcinoma of the palpebral mucocutaneous junction. A clinical, light microscopic and electron microscopic study of an unusual tubular variant.

An 81-year-old man developed a left lower lid lesion. The lid margin was red, thickened, and indurated with foci of ulceration and telangiectasia on the palpebral conjunctiva. The initial clinical impression was either a chalazion or sebaceous carcinoma, and an incisional biopsy was performed. By light and electron microscopy, the tumor demonstrated infiltrating cords of cells with an admixture of epidermoid and mucus-secreting elements arranged in a distinctive elongated tubular fashion. The involved lid was resected and reconstructed by a Hughes' tarso-conjunctival graft with marsupialization of the canaliculus. No recurrence has been encountered after a year. Mucoepidermoid carcinoma of the conjunctiva is a rare, locally aggressive neoplasm characterized in all seven previously reported cases by recurrence within 6 months, and a high incidence of intraocular or orbital invasion.

Epibulbar subconjunctival fibroma. A tumor possibly arising from Tenon's capsule.

A fibroma, a benign neoplasm arising from the periorbita or tendon sheaths, is described in a 74-year-old woman as an indolent, lobular tumor situated in the episcleral and subconjunctival connective tissues with superior limbal fixation. Because most fibromas arise from tendon sheaths or fascial planes, we speculate that our lesion arose from Tenon's capsule. The rarity of periocular fibroma is documented by a review of the modern ophthalmic literature. Histopathologically, the tumor was composed of a paucicellular population of fibroblasts, sometimes displaying hyperchromatic nuclei and widely separated by abundant broad bundles of collagen. Mast cells were infrequently dispersed in the lesion. A wide local excision was performed, and no recurrence has developed during an 18-month follow-up period.

Autotrophic picoplankton in the tropical ocean.

In phytoplankton of the eastern tropical Pacific Ocean from 25 to 90 percent of the biomass (measured as chlorophyll a) and 20 to 80 percent of the inorganic carbon fixation were attributable to particles that could pass a screen with a 1-micrometer pore diameter. Evidence is presented that these are indeed autotrophic cells and not cell fragments.

Retrocorneal pigmentation secondary to iris stromal melanocytic proliferation.

A 40-year-old black man had two penetrating keratoplasties as a result of complications from alkali burns sustained many years earlier. Two further penetrating keratoplasties were performed for recurrent retrocorneal pigmentation. Both scanning and transmission electron microscopy demonstrated that the retrocorneal pigmented cells were iris melanocytes, based upon their fusiform or dendritic shapes and measurements of their cytoplasmic melanin granules. Repopulation of Descemet's membrane by the melanocytes was produced by a small remnant of atrophic iris. The pigment granules in the iris melanocytes were somewhat larger than those seen in similar cells from Caucasians or Orientals, but had identical measurements to those studied in an iridectomy specimen from another black patient. The retrocorneal iris melanocytes were able to synthesize banded basement membrane material, interrupted laminar basement membrane, and collagen fibrils. The cause of the exfoliation of the iris melanocytes onto the back of the cornea is unknown, but the discovery that iris melanocytes can proliferate in an ongoing fashion and secrete extracellular matrix provides new insight into the physiology of these cells.