Hypersensitive knockin mouse strains identify receptors and pathways for nicotine action

Two series of knockin mouse strains have been constructed with point mutations that result in hypersensitive neuronal nicotinic acetylcholine receptors containing alpha 4- or alpha 7-subunits. The full expression of the stronger alleles produces neonatal excitotoxic lethality; however, mice with attenuated expression or milder alleles are viable, and display a range of hypersensitive responses to nicotine. To date, measurements have been made on nicotine-induced seizures, Straub tail, hypothermia, antinociception, electroencephalograms and cellular electrophysiological responses. These strains are helping to define the occurrence of these important receptor subtypes, and their role in the acute and chronic actions of nicotine. The hypersensitive strains may be useful for the development of nicotinic drug therapy.     

Consanguinity and apnea of prematurity

Consanguinity, marriage between relatives, has been associated with perinatal mortality and morbidity. Apnea of prematurity is defined as the cessation of breathing for longer than 20 seconds or that of any duration if accompanied by cyanosis and sinus bradycardia, for infants born before 37 weeks of gestation. The objective of the study was to examine the association between consanguinity and apnea of prematurity in Greater Beirut, an area having a relatively high prevalence rate of consanguineous marriages. The study was cross-sectional. Between September 1, 1998, and March 31, 2001, 21723 newborn infants were admitted to the National Collaborative Perinatal Neonatal Network in Greater Beirut, Lebanon. The inclusion criteria were infants less than 37 weeks of gestation who were admitted to the intensive care unit, with no congenital malformations, sepsis, or neurologic disorders. Analysis was based on 597 infants of whom 66 had apnea of prematurity. With adjustment for weeks and type of gestation, pregnancy complications, and Apgar score, the odds ratio of apnea of prematurity for first-degree consanguineous parents as compared with other marriages was 2.9 (95% confidence interval: 1.3, 6.4). In addition to the recognized etiologic factors for apnea of prematurity, this study suggests a role played by genetic factors.     

Effect of hindlimb suspension and clenbuterol treatment on polyamine levels in skeletal muscle

Polyamines are unbiquitous, naturally occurring small aliphatic, polycationic, endogenous compounds. They are involved in many cellular processes and may serve as secondary or tertiary messengers to hormonal regulation. The relationship of polyamines and skeletal muscle mass of adductor longus, extensor digitorum longus, and gastrocnemius under unloading (hindlimb suspension) conditions was investigated. Unloading significantly affected skeletal muscle polyamine levels in a fiber-type-specific fashion. Under loading conditions, clenbuterol treatment increased all polyamine levels, whereas under unloading conditions, only the spermidine levels were consistently increased. Unloading attenuated the anabolic effects of clenbuterol in predominately slow-twitch muscles (adductor longus), but had little impact on clenbuterol's action as a countermeasure in fast- twitch muscles such as the extensor digitorum longus. Spermidine appeared to be the primary polyamine involved in skeletal muscle atrophy/hypertrophy.     

Risk factors of osteoporosis in healthy Moroccan men

Background  

Although not as common as in women, osteoporosis remains a significant health care problem in men. Data concerning risk factors of osteoporosis are lacking for the male Moroccan population. The objective of the study was to identify some determinants associated to low bone mineral density in Moroccan men.     

Effect of a novel drug-eluted balloon coated with Genistein before stent implantation in porcine coronary arteries

Background  The major drawback of stent implantation in native human coronary vessels is the occurrence of restenosis. Drug-eluting stents significantly reduce restenosis after percutaneous coronary intervention (PCI), but may be associated with persistent local inflammation involved in the restenosis mechanisms. In this setting coating coronary devices with anti-inflammatory agents represents an intriguing alternative to stent-based local drug delivery. The aim of the present study was to test in a porcine model the safety and efficacy of a novel Genistein-eluting balloon preceding coronary stenting. Design  Female piglets underwent PCI in a randomized fashion with either a Genistein-eluting or a standard balloon angioplasty, followed in all vessels by bare-metal stent implantation. Pigs were sacrificed at different time points to appraise safety (i.e. endothelialization) and efficacy (i.e. anti-inflammatory and anti-proliferative effects): 1, 4, and 6–8 weeks following PCI. Results  Overall analysis was conducted on 14 piglets. Twenty-five bare-metal stents were implanted preceded by angioplasty with a conventional balloon in 13 vessels and by the Genistein-eluted balloon in 12. No untoward effects were reported in either group. Healing and endothelialization appeared universal within 4 weeks. The Genistein-eluted balloon group disclosed a significant reduction, at four weeks from implantation, of the peri-stent inflammatory cells count (mononucleocytes 39 ± 32 Vs. 96 ± 29 per square millimetre, P = 0.019). This effect did not clearly translate into a trend towards a reduced neointimal hyperplasia at 6–8 weeks (0.13 ± 0.11 Vs. 0.14 ± 0.09, P = 0.835). Conclusion  This study provides the first in vivo demonstration of the anti-inflammatory effects of a Genistein-eluting balloon in PCI, warranting further research including the combination of a Genistein-eluting balloon with standard drug-eluting stent.     

Ultrasonographic nomograms of the fetal fourth ventricle: additional tool for detecting abnormalities of the posterior fossa.

OBJECTIVE: To characterize normal growth of the fetal fourth ventricle on ultrasonography throughout pregnancy. METHODS: Consecutive biometric measurements and fetal organ scans were obtained from 299 patients undergoing fetal anatomic surveys between 13 and 40 weeks' gestation. Using 7- and 3.5-MHz transducers for early (13- to 17-week) and late (>17-week) examinations, respectively, we scanned the fetal head in the axial plane with special focus on the posterior fossa of the brain. The fourth ventricle was identified, and its anteroposterior diameter and width were measured. A "triangle" formula was used for calculating its circumference and area. RESULTS: The fourth ventricle was shown as a hypoechoic triangle below the level of the cerebellum. A linear regression line of the fourth ventricle was observed across gestational age, and a first-degree correlation was found between gestational age and anteroposterior diameter of the fourth ventricle (r = 0.894; P < .0001; y = -0.84 + 0.23 x gestational age), its width (r = 0.657; P < .0001; y = 3.82 + 0.14 x gestational age), its circumference (r = 0.843; P < .0001; y = 5.11 + 0.58 x gestational age), and its area (r = 0.844; P < .0001; y = -10.11 + 1.17 x gestational age). Twelve enlarged fourth ventricles were found between 14 and 16 weeks, but results of follow-up scans at 20 weeks were normal. CONCLUSIONS: An isolated enlarged fourth ventricle in the early second trimester might represent a normal variant; it should be followed, but decisions about the fate of the pregnancy should not be based solely on this finding.