Detection of early gamma-postirradiation effects in murine spleen by proton NMR relaxation times.

BACKGROUND: It was our aim to evaluate the potential of proton relaxation times for the early detection of radiation-induced spleen changes. MATERIALS AND METHODS: Female Swiss mice were irradiated with doses ranging from 0.05 Gy to 4 Gy. The body weight, the spleen weight and the spleen water content of single animals were determined. Measurements of longitudinal (T1) and transversal (T2) proton relaxation times of the spleen samples were performed in a 0.47 T spectrometer. Histological examinations of the control and irradiated organs were performed. RESULTS: NMR measurements during the first five days after irradiation showed that total body gamma-irradiation with doses from 1.5 Gy to 4 Gy results in decreasing T1 of the murine spleen. Significant shortening in T2 was observed for the spleen of animals irradiated with a dose of 4 Gy. Histological examinations demonstrated subnormal architecture in slices derived from animals irradiated with 2 Gy and 4 Gy. CONCLUSION: The fluctuations of the spleen T1 and T2 of irradiated mice are correlated with relative spleen weight and can be used to estimate radiation induced changes in this organ.

Serotonin (5-HT2) receptor mediated enhancement of cortical unit activity.

Simultaneous single-unit and intracortical activity were recorded from neocortical neurons in urethane-anaesthetized rats to investigate the role of serotonin (5-HT) in modifying cortical excitability. Units, at a depth of 775-1100 microns from the pial surface, discharged in a burst-pause pattern that was correlated with slow wave activity. Application of noxious somatic stimulation resulted in cortical desynchronization and altered the pattern of unit activity such that firing was continuous, i.e., the pauses were eliminated. Intravenous administration of the mixed 5-HT1C/5-HT2 antagonists (cinanserin, cyproheptadine, ketanserin, and ritanserin) prevented both desynchronization and the change in unit activity induced by noxious stimulation within 2.5-15 min of the injection. The basic pattern of burst-pause activity remained intact, but the number of spikes per burst was typically reduced, whereas interburst intervals were increased. Iontophoretic application of these antagonists onto cortical neurons resulted in actions similar to those observed following systemic administration. Intravenous and iontophoretic application of m-trifluomethylphenylpiperazine (5-HT1C agonist, 5-HT2 antagonist) resulted in actions indistinguishable from those observed with the above antagonists, from which we conclude 5-HT2 and not 5-HT1C receptors mediate the alteration in unit activity observed with noxious stimulation. The results are discussed with respect to an interaction between N-methyl-D-aspartate and 5-HT2 receptors leading to the enhanced unit activity observed with noxious stimulation.

Human immunodeficiency virus-related Kaposi's sarcoma of the appendix and acute appendicitis. Report of a case and review of the literature.

We describe a case of acute appendicitis precipitated by human immunodeficiency virus-related Kaposi's sarcoma of the appendix. This presentation in an otherwise asymptomatic homosexual man led to the establishment of a diagnosis of acquired immunodeficiency syndrome. Immediate follow-up revealed multicentric gastrointestinal involvement by Kaposi's sarcoma, and skin involvement ensued in 2 months. Salient features of this case and two other similar reports in the literature are highlighted.