Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0728731 (prematurity)
 7,134 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The perinatal mortality rate for twin gestation is in the range of 15%, and this is due predominantly to prematurity, although twins may also be born growth retarded. Ritodrine HCl, a beta sympathomimetic drug, has been shown to be effective, both in stopping premature labor and in preventing intrauterine growth retardation. With this in mind, a double-blind study using ritodrine HCl or placebo was begun in order to study its effect on premature labor, intrauterine growth retardation, and the perinatal mortality rate in twins. Thus far, 30 patients have delivered and have been followed to 6 weeks postpartum. Although the results on individual patients have remained blinded to the investigators, an initial evaluation of the ritodrine and placebo groups have revealed no difference with respect to gestational age, birth weight, or perinatal mortality. These preliminary results are not significant. However, it appears that ritodrine HCl is a safe oral agent for the antepartum gravida and her fetus. The study will be continued until approximately 100 patients have been enrolled.
 ...
PMID:Ritodrine HCL for the prevention of premature labor in twin pregnancies. 80 12

Laryngeal chemoreflexes (LCR) are triggered by the contact of liquids with the laryngeal mucosa. In the mature organism, LCR trigger lower airway protective responses (coughing, effective swallowing, and arousal) to prevent aspiration. General belief holds that LCR are responsible for apnea and bradycardia in the newborn mammal, including humans. Our laboratory has recently shown that LCR in full-term lambs are consistently analogous to the mature LCR reported in adult mammals, without significant apneas and bradycardias (St-Hilaire M, Nsegbe E, Gagnon-Gervais K, Samson N, Moreau-Bussiere F, Fortier PH, and Praud J-P. J Appl Physiol 98: 2197-2203, 2005). The aim of the present study was to assess LCR in nonsedated, newborn preterm lambs born at 132 days of gestation (term = 147 days). The preterm lambs were instrumented for recording glottal adductor electromyogram, electroencephalogram, eye movements, heart rate, respiration, and oximetry. A chronic supraglottal catheter was used for injecting 0.5 ml of saline, distilled water, and HCl (pH 2) during quiet sleep, active sleep, and wakefulness on postnatal days 7 (D7) and 14 (D14). Laryngeal stimulation by water or HCl on D7 induced significant apneas, bradycardia, and desaturation, which, at times, appeared potentially life-threatening. No significant apneas, bradycardias, or desaturation were observed on D14. No consistent effects of sleep state could be shown in the present study. In conclusion, laryngeal stimulation by liquids triggers potentially dangerous LCR in preterm lambs on D7, but not on D14. It is proposed that maturation of the LCR between D7 and D14 is partly involved in the disappearance of apneas/bradycardias of prematurity with postnatal age.
 ...
PMID:Postnatal maturation of laryngeal chemoreflexes in the preterm lamb. 1717 Feb 7

In a mature organism, the contact between various liquids and the laryngeal mucosa triggers lower airway protective responses (cough, swallowing, arousal). These laryngeal chemoreflexes (LCR) are essential for preventing aspiration. In contrast, previous studies showed that LCR are responsible for apnea and bradycardia in the neonatal mammal. Consequently, LCR, especially when triggered by acid gastrolaryngeal reflux, are deemed responsible for some apneas of prematurity and many life-threatening events of infancy and, probably, for some cases of sudden infant death syndrome. Recently, we have revisited LCR in full-term lambs during quiet sleep. Our results showed that the LCR triggered by HCl (pH 2), mimicking the acid component of an acid gastro-oesophageal reflux, were consistently like the mature LCR reported in adult mammals, without significant apneas and bradycardias (St-Hilaire 2005). These results prompted us to question whether premature birth alters LCR. Results show that LCR triggered in pre-term lambs by both saline and HCl are much more marked and clinically relevant than the ones observed in full-term lambs. Indeed, life-threatening responses to HCl, including repetitive apneas for more than 90 seconds, severe desaturation and bradycardia, were observed in 2 lambs at postnatal day 7 (D7). In addition, LCR were significantly blunted at D14. In conclusion, HCl can trigger potentially dangerous LCR in pre-term lambs at D7, suggesting that LCR in response to acid gastrolaryngeal refluxes are likely involved in some apnea/bradycardia/desaturation in pre-term infants, before they reach a post-conceptional age equivalent to full gestation.
 ...
PMID:Laryngeal stimulation by an acid solution in the pre-term lamb. 1808 64