Risk factors for hearing loss from meningitis in children: the Children's Hospital experience.

OBJECTIVES: To identify statistically significant risk factors for hearing loss in children with meningitis, determine the overall incidence of hearing loss in a large group of children with confirmed meningitis, and quantify the percentage of children with progressive or fluctuating hearing loss after meningitis. DESIGN: Retrospective analysis. PATIENTS AND OTHER PARTICIPANTS: Four hundred thirty-two children admitted to the Children's Hospital, Birmingham, Ala, from January 1, 1985, to December 31, 1995, with the diagnosis of meningitis. RESULTS: Of 432 children with meningitis, 59 (13.7%) had the development of hearing loss. Of these 59 children, 46 (78.0%) had stable sensorineural hearing loss and 13 (22.0%) had either progressive or fluctuating hearing loss. Of the variables examined using multiple logistic regression backward-elimination modeling, only 5 appeared to be significantly associated with the development of hearing loss: computed tomographic scan evidence of increased intracranial pressure (estimated odds ratio [OR] = 2.3), male sex (OR= 1.9), the common logarithm of glucose levels in the cerebrospinal fluid (OR = 0.58), Streptococcus pneumoniae as the causative organism (OR= 2.1), and the presence of nuchal rigidity (OR = 1.9). In the children with progressive hearing loss, the time for progression varied from 3 months to 4 years before hearing stabilized. CONCLUSIONS: In this study of children diagnosed as having meningitis, hearing loss developed in 59 (13.7%). Forty-six (78.0%) of these children with hearing loss had stable auditory thresholds over time, and 13 (22.0%) exhibited deterioration or fluctuation of acuity over time. Evidence of increased intracranial pressure by computed tomographic scan, male sex, low glucose levels in the patients' cerebrospinal fluid, S pneumoniae as the causative organism, and the presence of nuchal rigidity appear to be significant predictors for future hearing loss.

Endomorphin 1 and 2, the endogenous mu-opioid agonists, produce biphasic changes in systemic arterial pressure in the cat.

The endogenous peptides endomorphin 1 and 2 are newly isolated, potent, selective mu-opioid receptor agonists. In the present study, responses to the endomorphin peptides were investigated in the systemic vascular bed of the cat. Endomorphin 1 and 2 induced dose-related biphasic changes in systemic arterial pressure when injected in doses of 1-30 nmol/kg i.v. The biphasic responses to endomorphin 1 and 2 were characterized by an initial increase followed by a decrease in systemic arterial pressure. In terms of relative vasodepressor activity, endomorphin 1 and 2 were similar in potency and approximately 10-fold less potent than the ORL1 ligand nociceptin (orphanin FQ) in decreasing systemic arterial pressure. The biphasic arterial pressure changes in response to endomorphin 1 and 2 were inhibited by the opioid receptor antagonist naloxone in a dose of 2 mg/kg i.v. These results demonstrate that endomorphin 1 and 2 produce significant, naloxone-sensitive changes in systemic arterial pressure that are characterized by an initial increase followed by a secondary decrease in arterial pressure in the cat.

Comparison of responses to rat and human adrenomedullin in the hindlimb vascular bed of the cat.

Responses to rat (r) adrenomedullin (ADM) and human (h) ADM were compared in the hindlimb vascular bed of the cat under conditions of controlled blood flow. Intra-arterial injections of rADM and hADM in doses of 0.03-1 nmol caused dose-related decreases in hindlimb perfusion pressure. In terms of relative vasodilator activity, rADM was similar to hADM. The time course of the vasodilator response and the recovery half times (T1/2) for the vasodilator response to rADM and hADM were not significantly different. Decreases in hindlimb perfusion pressure in response to rADM and hADM were not altered by the calcitonin gene-related peptide receptor antagonist, rCGRP(8-37), at the same time, vasodilator responses to calcitonin gene-related peptide (CGRP) were significantly reduced. The T1/2 of the vasodilator response to rADM and hADM were significantly greater after administration of the cAMP-selective, type IV phosphodiesterase inhibitor, rolipram. These data demonstrate that decreases in hindlimb perfusion pressure in response to rADM and hADM are similar and that vasodilator responses to rADM are not dependent on the activation of CGRP receptors in the hindlimb vascular bed of the cat. These data further suggest that decreases in hindlimb perfusion pressure in response to rADM are mediated by smooth muscle increases in cAMP levels.

Abnormal polarity of thunderclouds grown from negatively charged air.

Experiments were carried out in New Mexico to determine whether the electrification processes that lead to the formation of lightning in clouds are influenced by the polarity of the charges in the air from which the clouds grow. The normal, positive space charge in the sub-cloud air was reversed by negative charge released from an electrified wire, suspended across a 2-kilometer-wide canyon. On more than four occasions when the clouds over the wire grew and became electrified, they were of abnormal polarity with dominant positive charges instead of the usual negative charges in the lower part of the cloud. The formation of these abnormally electrified clouds suggests both that the electrification process in thunderclouds can be initiated and that its polarity may be determined by the small charges that are present in the atmosphere.