Kainic acid-induced seizures: changes in brain extracellular ions as assessed by intracranial microdialysis

The effect of kainic acid on extracellular [K+], [Ca2+], and [Na+] in the rat piriform cortex and hippocampus was studied by means of intracranial microdialysis. Either a dialysis fiber loop or horizontal Vita fiber were stereotaxically implanted within the piriform cortex or hippocampus, respectively. About 24 h later, fibers were perfused (1 ml/min) with Krebs-Ringer bicarbonate solution. Effluent samples were collected before (four at 30 min intervals), and after (six at 30 min intervals) administration of kainic acid (16 mg/kg, i.p.) or kainic acid vehicle. Kainic acid induced sequential signs of lethargy, staring, "wet-dog shakes," forepaw clonus, and tonic-clonic convulsions. In these awake free-moving rats, kainic acid induced a rapid and prolonged increase in extracellular [K+] and an apparent, but not statistically significant, decrease in extracellular [Ca2+] within the hippocampus. In the piriform cortex, kainic acid induced increases in extracellular [K+] and [Na+], which were associated with early pre-convulsive signs. In contrast to the pronounced ion changes commonly seen when the brain is activated by factors such as local application of excitatory substances or when the brain is made ischemic or hypoxic, extracellular ion concentrations are relatively well maintained during parenteral kainic acid-induced seizures.     

Prolactin-releasing activity of porcine intestinal peptide (PHI-27)

Porcine intestinal peptide (PHI), a twenty-seven amino acid peptide isolated from porcine gut extracts, is a close structural homolog of the secretin family hormones. The structural and biological similarities of PHI to vasoactive intestinal peptide (VIP) together with its presence in the rat hypothalamus suggested a possible role for the peptide in the control of prolactin (PRL) secretion. PHI induced significant, dose-related stimulations of PRL release from cultured, dispersed rat pituitary cells in vitro. The minimum effective dose is 10⁷ molar, compared to 10⁹ molar for VIP. No interactive effect with thyrotropin-releasing hormone was observed; however, PHI partially overcame the dopamine inhibition of PRL release.     

Induction of Sporulation During Synchronized Chromosome Replication in Bacillus subtilis

Synchronous chromosome replication was obtained in a culture of Bacillus subtilis temperature-sensitive mutants growing in a rich medium. At intervals during this replication, samples of cells were transferred to a poor medium to induce sporulation. The results show that the capacity of B. subtilis for induced sporulation reaches a peak about 15 min after chromosome replication has begun. This capacity then declines rapidly, but can be restored by initiating a new round of deoxyribonucleic acid replication. The possibility is discussed that sporulation can be induced only when the chromosome replication fork is passing through a stage 0 operon and that this may be located in the cysA-sul(R) region of the chromosome.     

Studies on reactivated cilia : I. The utilization of various nucleoside triphosphates during ciliary movement

It has been found that the movement of reactivated cilia is prolonged, providing various nucleoside triphosphates (NTP) are present in the reactivation medium in addition to ATP. The results suggest the existence of an axoneme-bound phosphotransferase that regenerates ATP from NTP. A model is proposed for the enzymatic regulation of ATP levels in the cilium.     

Changes in Extracellular Amino Acids During Soman-and Kainic Acid-Induced Seizures

Extracellular amino acid levels in the rat piriform cortex, an area highly susceptible to seizure-induced neuropathology, were determined by means of intracranial microdialysis. Seizures were induced by systemic administration of either soman (O-1,2,2-trimethylpropyl methylphosphonofluoridate), a potent inhibitor of acetylcholinesterase, or the excitotoxin kainic acid. Extracellular glutamate levels increased in animals with seizures shortly after administration of either convulsant, but this change was statistically significant only in the case of soman-treated animals. Extracellular taurine levels increased markedly, reaching two- and fourfold baseline levels during the second hour of soman- and kainic acid-induced seizures, respectively. Taurine levels did not increase in the subpopulation of soman-treated animals without seizures, a finding indicating that elevation of extracellular taurine level is seizure related. Thus, we propose that taurine efflux may be a physiological cellular response to neuronal changes produced by excitotoxic chemicals, either directly or as a consequence of seizures.     

Paracoccidioidomycosis in a four-year-old boy

Summary A case of fatal, generalized paracoccidioidomycosis is described in a four-year-old urban dwelling child. Marked lympadenopathy, hepatosplenomegaly and an abdominal mass were the main clinical manifestations. The diagnosis was established by histopathological studies and culture. The authors comment on the rarity of this infection in children less than 7 years of age and on the importance of considering this pathology in the differential diagnosis of malignant non-Hodgkin lymphoma and tuberculosis, in children.Medical Student of the Federal University of Bahia.     

Chromatographic and biologic analysis of ME and OVLT LHRH

The luteinizing hormone (LH)-releasing activities a pooled rat organum vasculosum lamina terminalis (OVLT) and median eminence (ME) tissues were evaluated for chromatographic and biologic similarity and compared to those of synthetic decapeptide LH-releasing hormone (LHRH). The LHRH detected in these extracts appeared similar chromatographically (Sephadex G-25) to synthetic LHRH. These extracts, as well as synthetic LHRH, were also capable of stimulating dose dependent gonadotropin release form cultures rat gonadotrophs. These findings suggest a physiological role of the LHRH present in the rat OVLT in the control of gonadotropin secretion.     

In vitro stimulation of prolactin release by vasoactive intestinal peptide

The effect of vasoactive intestinal peptide (VIP) on anterior pituitary hormone release was examined in a variety of in vitro preparations. Synthetic VIP was capable of stimulating increased prolactin (PRL) release from male rat hemipituitaries in doses as low as 10⁻⁹ M only when the enzyme inhibitor bacitracin was present in the incubation medium. Natural porcine VIP was similarly capable of stimulating PRL release, but only at higher doses (10⁻⁶ M). Additionally, synthetic VIP was capable of stimulating PRL release from dispersed anterior pituitary cells harvested from adult male and lactating female rats and from an enriched population of lactotrophs obtained by unit gravity sedimentation of similar dispersed cells from infantile female rats. No effect of VIP on luteinizing hormone, growth hormone or thyroid stimulating hormone release was seen. These findings taken in concert with the presence of VIP in the hypothalamus, pituitary and hypophyseal portal plasma of the rat suggest a physiological role for VIP in the control of PRL secretion.     

Rheumatic Fever and Rheumatic Heart Disease in Barbados: Detection and Prophylaxis

The objectives of this study were to improve our methods of secondary prophylaxis of rheumatic fever and rheumatic heart disease in Barbados, to estimate the overall prevalence of these diseases and the relative load imposed by them on available health services, and to measure the yield, feasibility, and effectiveness of mass programmes for the detection and prophylactic management of rheumatic heart disease in schoolchildren.Improved methods of surveillance and follow-up resulted in 97% adherence to therapy by patients on prophylactic penicillin. Thirty-four children, 27 with a first attack, were admitted with acute rheumatic fever, representing a 7% occupancy of children''s medical beds during the 12-month period of the study. Out of a possible 3,942 schoolchildren aged 5-11 years, 3,882 (98%) were screened for rheumatic heart disease. Four cases (about 1 per 1,000) were discovered.