Late aspergilloma of a renal allograft without need for operative management: a case report and review of the literature.

Aspergillus infection localized to the renal allograft is a rare and potentially life-threatening infection and typically requires a combination of operative and medical management. We report the case of a renal allograft aspergilloma in a renal transplant patient presenting 2 years post transplant, successfully managed non-surgically. To our knowledge, this is the first report of a patient presenting with an allograft aspergilloma so long after transplantation and being successfully managed with antifungal therapy alone.

Several GABAA receptor subunits are expressed in LHRH neurons of juvenile female rats.

Gamma aminobutyric acid (GABA), the dominant inhibitory neurotransmitter in brain, is involved in the developmental regulation of LHRH secretion. Morphological studies in rodents have demonstrated that LHRH neurons are innervated by GABA-containing processes, suggesting that LHRH secretion is under direct transsynaptic GABAergic control. While GABA acts through two different receptors, GABAA and GABAB, to exert its effects, it appears that GABAA receptors are able to mediate both inhibitory and stimulatory effects of GABA on LHRH neurons. GABAA receptors are heterooligomeric ligand-gated anion channels that exhibit a diverse array of functional and pharmacological properties. This diversity is determined by the structural heterogeneity of the receptors, which are assembled from the combination of different classes of subunits with multiple isoforms. Although several studies have described the effect of GABAA receptor stimulation on LHRH and/or gonadotropin release in prepubertal animals, nothing is known about the receptor subunits that may be expressed in LHRH neurons at this phase in development. Double immunohistofluorescence followed by confocal laser microscopy revealed that subsets of prepubertal LHRH neurons are endowed with alpha 1, alpha 2, beta 2/3, and gamma 2 GABAA receptor subunits. Combined immunohistochemistry for LHRH neurons and in situ hybridization for GABAA subunit mRNAs confirmed that the genes encoding the alpha 1, alpha 2, beta 3 and gamma 2 subunits, but not the gamma 1 subunit, are expressed in LHRH neurons. Notwithstanding the relative insensitivity of these methods, both the immunohistochemical and hybridization histochemical approaches employed indicate that only a fraction of LHRH neurons are endowed with GABAA receptors. This arrangement suggests that those LHRH neurons bearing the appropriate GABAA receptors are responsible for either the entire secretory response to direct GABAergic inputs or for its initiation.

Effects of Gd-DTPA after osmotic BBB disruption in a rodent model: toxicity and MR findings.

OBJECTIVE: This experiment was done to evaluate the gross neurotoxicity of intravenous Gd-DTPA administered in conjunction with osmotic blood-brain barrier (BBB) disruption and to image a human small cell lung carcinoma intracerebral tumor xenograft before and after osmotic BBB disruption. MATERIALS AND METHODS: Neurotoxicity studies were performed in normal Sprague-Dawley rats following osmotic BBB disruption by the injection of 25% mannitol in the right internal carotid artery and intravenous administration of Gd-DTPA (n = 10). Animals were observed for major neurologic changes such as seizure or substantial motor defects, and after death neuropathologic examination was performed. Human small cell lung carcinoma cells were implanted intracerebrally in athymic nude rats (n = 4). Gadopentetate dimeglumine was injected intravenously and serial T1-weighted images were obtained. Blood-brain barrier disruption was produced in each animal, followed by a second dose of intravenous Gd-DTPA, and imaging studies were repeated. RESULTS: No gross neurologic toxicity was observed. Tumors showed dense enhancement in a small area, and BBB disruption resulted in marked enhancement in most of the gray matter of the right cerebral hemisphere. CONCLUSION: Gadopentetate dimeglumine appears to be safe in doses up to 21 mmol/m2 in conjunction with barrier disruption in rats. A human small cell lung carcinoma intracerebral xenograft provides a useful method to study brain tumors.

Syndrome of inappropriate secretion of antidiuretic hormone in a patient with carcinoma of the nasopharynx.

A patient with a primary undifferentiated carcinoma of the nasopharynx manifested the clinical syndrome of inappropriate antidiuretic hormone secretion (SIADH). Immunohistochemical techniques demonstrated the presence of vasopressin, neurophysin, and their precursor (propressophysin) in the cancer cells. In situ hybridization additionally confirmed the expression of propressophysin messenger RNA in these cells. To the knowledge of the authors, this represents not only the first case of SIADH caused by carcinoma of the nasopharynx, but also the first report of pathologic confirmation of the syndrome with the use of both molecular and immunologic probes.

Immunological studies with a monoclonal antibody suggest a different conformation of neurophysin in parvicellular neurons of rat hypothalamus.

A monoclonal antibody (mAb L6) to a carcinoma surface antigen has previously been shown to recognize neurophysins (NP), proteins associated with oxytocin and vasopressin. L6-reactivity in rat hypothalamus was confined to magnocellular neuronal systems. No staining was detected in parvicellular suprachiasmatic or paraventricular systems. mAb L6 immunoprecipitated vasopressin-neurophysin only under reducing conditions, and detected it in Western blots only after gel-renaturation and electroblotting in basic buffer. These findings suggest L6-reactivity to NP is conformation-sensitive, and imply NP expression in a unique configurational form in hypothalamic parvicellular systems.