Pharmacokinetic properties of enrofloxacin in rabbits.

The pharmacokinetic properties of the fluoroquinolone antimicrobial enrofloxacin were studied in New Zealand White rabbits. Four rabbits were each given enrofloxacin as a single 5 mg/kg of body weight dosage by IV, SC, and oral routes over 4 weeks. Serum antimicrobial concentrations were determined for 24 hours after dosing. Compartmental modeling of the IV administration indicated that a 2-compartment open model best described the disposition of enrofloxacin in rabbits. Serum enrofloxacin concentrations after SC and oral dosing were best described by a 1- and 2-compartment model, respectively. Overall elimination half-lives for IV, SC, and oral routes of administration were 2.5, 1.71, and 2.41 hours, respectively. The half-life of absorption for oral dosing was 26 times the half-life of absorption after SC dosing (7.73 hours vs 0.3 hour). The observed time to maximal serum concentration was 0.9 hour after SC dosing and 2.3 hours after oral administration. The observed serum concentrations at these times were 2.07 and 0.452 micrograms/ml, respectively. Mean residence times were 1.55 hours for IV injections, 1.46 hours for SC dosing, and 8.46 hours for oral administration. Enrofloxacin was widely distributed in the rabbit as suggested by the volume of distribution value of 2.12 L/kg calculated from the IV study. The volume of distribution at steady-state was estimated at 0.93 L/kg. Compared with IV administration, bioavailability was 77% after SC dosing and 61% for gastrointestinal absorption. Estimates of predicted average steady-state serum concentrations were 0.359, 0.254, and 0.226 micrograms/ml for IV, SC, and oral administration, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Primary intracranial melanoma presenting as a suprasellar tumor.

A 37-year-old white woman presented with progressive visual loss in the right eye. The diagnostic evaluation suggested a tumor in the suprasellar area. At operation an isolated melanoma was found just superior to the sella turcica. No evidence of other intracranial lesions was present and complete diagnostic studies failed to reveal any other primary site. The patient subsequently underwent a second neurosurgical procedure in an effort to remove the tumor completely. This was followed by recurrent symptomatology and she was then treated with a combination of multiple drug chemotherapy and immunotherapy. Approximately 3 years after her initial operation the patient succumbed secondary to her disease. The autopsy findings were consistent with a primary melanoma of the leptomeninges in the area just above the sella turcica. This unusual presentation is discussed and plausible hypotheses are given.

Cloacogenic carcinoma.

Cloacogenic carcinoma is a rare tumor of the anorectal region originating from a persistant remnant of the cloacal membrane of the embryo. The tumor accounts for 2-3% of anorectal carcinomas and occurs more than twice as often in women. Most tumors present as fungating or ulcerating lesions, but the tumor may arise in anal ducts and present as a submucosal mass. Wide abdominoperineal resection is the treatment of choice with a five year survival of 50%. Metastases occurs to the inguinal lymph nodes in more than 50% of the patients at sometime during the course of the disease with distant metastases occuring most commonly to liver and lungs.

Hemidesmosome-like intercellular specializations in human meningiomas.

Desmosomes, gap junctions and tight junctions are intercellular specializations which have been described in human meningiomas. We report, in five of five meningiomas, including a pulmonary metastasis from a malignant intracranial meningioma, a fourth type of intercellular specialization which is similar to but not identical with the hemidesmosome of the epidermis. Idential intercellular specializations have been described between arachnoidal cells, but not between dural fibroblasts. The presence of the junction in human meningeal neoplasms of diverse histologic pattern supports the origin of the meningioma from arachnoidal epithelium. The consistent occurrence of these structures in a pulmonary metastasis as well as benign intracranial tumors suggests that they may be a useful morphologic marker in the differential diagnosis of putative extracranial metastatic meningiomas.

Glial-mesenchymal tropism of in vivo avian sarcoma virus neuro-oncogenesis in rats.

Intracerebral inoculation of avian sarcoma virus (ASV) in postnatal animals induces gliomas and sarcomas but no neuronal tumors. High titer Bratislava-77 strain ASV was inoculated intracerebrally in fetal F-344 rats between 17 and 20 days of gestation: a time of active neuronal proliferation. Following birth inoculated rats developed gliomas and sarcomas but no neuronal tumors. The results are evidence that the glial-mesenchymal tropism of in vivo ASV neuro-oncogenesis is independent of stage of neurocytodifferentiation at inoculation.

Calcification of basal ganglia and cerebellar roof nuclei in mentally defective patient with hidrotic ectodermal dysplasia. Analysis of intracranial concretions by electon microprobe.

This report describes, for the first time, an analysis by electron microprobe of concretions in the brain of an individual with striopallidodentate calcification. We also report the unique association of this intracranial syndrome with hidrotic ectodermal dysplasia. An institutionalized male with impaired intellectual function and hidrotic ectodermal dysplasia was known since the age of 3 years to have bilateral radiopaque densities in the region of the basal ganglia on skull roentgenogram. He died at age 29 in congestive heart failure from rheumatic pancarditis. At autopsy, concretions were identified in globus pallidus, caudate nuclei, thalamus, and dentate nuclei. Mineral deposits within the brain, analyzed by energy dispersive x-ray microanalysis, consisted predominately of calcium and phosphorus. Trace amounts of magnesium, iron, and silicon also were detected.

Influence of age at inoculation on avian oncornavirus-induced brain tumor incidence, tumor morphology, and postinoculation survival in F344 rats.

Intracranial neoplasms were induced by intracerebral inoculation of a standardized, cell-free inoculum of the Bratislava-77 strain of avian sarcoma virus in F344 rats at 1, 9,97 to 99, and 528 days of age. Deaths from diseases that occur spontaneously in aged F344 rats complicated assessment of tumor incidence in rats inoculated at 528 days; 20 of 30 rats inoculated at this age developed brain tumors. All rats inoculated at age 1 day (47 rats), at age 9 days (37 rats), and at 97 to 99 days of age (41 rats) developed brain tumors. The incidence of animals developing tumors was 100% in these three groups, but the incidence of multiple tumors declined with increasing age at inoculation. The mean and variance of postinoculation survival increased from 83.8 +/- 21.5 days for rats inoculated at 1 day of age to 284.6 +/- 151.5 days for rats inoculated at 97 to 99 days of age. Poorly differentiated astrocytomas and astrocytomas of mixed morphology were common among rats inoculated as neonates. Solitary, pilocytic astrocytomas were the most common tumors among rats inoculated as adults.

The role of the subependymal plate in avian sarcoma virus brain tumor induction: comparison of incipient tumors in neonatal and adult rats.

F-344 rats were inoculated intracerebrally at 1 and at 133 days of age with the Bratislava-77 strain of avian sarcoma virus. Groups of rats were sequentially sacrificed following inoculation so that early stages of microtumor formation could be evaluated. In neonatally inoculated rats incipient tumors developed in the subependymal region of the lateral ventricles in close juxtaposition to clusters of poorly differentiated germinal cells. Among these animals microtumors were detected as soon as 2 weeks after inoculation; by 4 weeks post-inoculation all rats inoculated at 1 day of age had tumors. In contrast among rats inoculated as adults incipient tumors developed in the cerebral cortex away from the subependymal region but adjacent to the locus of inoculation. Incipient tumors were uncommon in rats inoculated as adults during the first 2 months after inoculation.

The fine structure of intracranial neoplasms induced by the inoculation of avian sarcoma virus in neonatal and adult rats.

Groups of F-344 rats were inoculated with the Bratislava-77 strain of avian sarcoma virus (B-77 ASV) within 24 hours of birth, at 9 days of age, or between 97 and 119 days of age. Intracranial tumors developed in each age group. Multiple tumors with mixed histologic patterns developed in rats inoculated at 1 or 9 days of age. Solitary tumors with a uniform histologic pattern developed in rats inoculated as adults. On the basis of light and electron microscopic study, the majority of tumors in each age group were classified as astrocytomas and divided into either poorly differentiated, gemistocytic, pilocytic, or polymorphic varieties. The polymorphic astrocytomas were most common among neonatally inoculated rats, while the pilocytic astrocytomas were most common among rats inoculated as adults. Ultrastructural characteristics of astrocytes, including gap junctions and 7- to 9-nm filaments, were present in the majority of tumors in each age groups. Astrocytomas induced in adult rats were remarkable for the presence of extensive basement membrane alone the astrocytic cell surfaces. Intracytoplasmic virus-like particles (R particles) were common in the tumor cells. These virus-like particles are morphologically distinct from C-type B-77 ASV, and no morphologic evidence of C-type virus replication was observed in any of the tumors.