Up-regulation of nicotinic acetylcholine receptors following chronic exposure of rats to mainstream cigarette smoke or α4β2 receptors to nicotine

Smokers are reported to have a higher density of central nicotinic acetylcholine receptors (nAChRs) that non-smokers at autopsy. Whether this increased receptor density is a response to smoking or a result of genetic variability is not known. While sub-chronic treatment of rats and mice with nicotine results in upregulation of central nAChRs, changes in receptor density in response to cigarette smoke have not been studied previously. In this study, male Sprague-Dawley rats were exposed nose-only for 13 weeks to mainstream cigarette smoke followed by assessment of [³H]nicotine binding in five brain regions of smoke- and sham-exposed animals. In smoke-exposed animals, there was a significant increase in nAChR density in the cortex, striatum, and cerebellum (35, 25, and 31% increases, respectively), while there was no significant change in receptor density in the thalamus and hippocampus. Smoke exposure did not alter markedly the affinity of the receptor for nicotine in these brain regions. Furthermore, up-regulation of nAChRs did not alter the biphasic binding properties by which nicotine binds to its receptor. There were no changes in the association (fast phase) or isomerization (slow phase) rate constants, and the percent contribution of slow and fast phase binding to nAChRs was not altered in the up-regulated receptor population compared with control. Similar results were observed following chronic nicotine exposure of cultured cortical cells from fetal rat brain or cells transfected with the α4β2 nAChR subtype. These results show that the up-regulation following smoke exposure in the rat is phenomenologically similar to that observed in vitro. These data provide preliminary evidence for a relationship between cigarette smoking and nAChR up-regulation in vivo and suggest that similar mechanisms of upregulation may underlie chronic smoke exposure of live animals and nicotine exposure of artificially expressed α4β2 receptors in vitro.     

In vivo measurement of the shear modulus of the human vocal fold: interim results from eight patients

The shear modulus of the vocal fold is an essential parameter required to enhance our understanding of how the vocal fold operates, to develop mathematical models of phonatation, and to provide benchmarks to quantify the effectiveness of surgical procedures. The authors announced the successful deployment of an instrument to measure vocal fold elasticity in vivo last year, and now present the data taken from eight patients in vivo. The shear modulus was measured at the mid-membranous point, in a transverse direction with respect to the axis drawn between the anterior commissure and vocal process. The range of mean shear modulus results is 701–2,225 Pa, with a mean value of 1,371 Pa.     

Guided bone regeneration for immediate non‐submerged implant placement using bioabsorbable materials in Beagle dogs

The aim of the present study was to evaluate the combined application of different bioabsorbable materials for healing of residual peri‐implant defects after placement of non‐submerged implants into fresh extraction sockets. Second and third mandibular premolars were extracted from 10 Beagle dogs, the coronal part of the distal sockets were surgically enlarged and this was followed by immediate placement of specially designed hollow‐screw non‐submerged dental implants. For each animal, the coronal peri‐implant defects were further treated with one of the 4 following procedures: 1) no treatment, control site: 2) grafting with porous hydroxyapatite (HA); 3) collagen membrane tightly secured around the implant and over the defect and 4) grafting with HA covered with a collagen membrane. After 16 weeks of healing, specimens were removed from the mandibule and prepared for a histomorphometric evaluation. The bone-to-implant contact length (BIC) was measured and compared amongst the different treatment modalities. In the defect area, the irregular bone regeneration was similar between all the treatment procedures ( P >0.10). In the sites covered with a collagen membrane alone, the total BIC (47%) was greater than in control sites (28.7%. P <0.05) or sites grafted with HA (22.2%, P <0.02). Total BIC in sites treated with the HA‐membrane combination (43%) was only significantly different from sites treated with HA ( P <0.10). It is concluded that the use of bioabsorbable materials results in a limited increase of osseointegration when used in conjunction with immediate placement of non-submerged implants, although the principle of the one stage surgical approach can be maintained.     

Surgery for left ventricular free wall rupture: patch glue repair without extracorporeal circulation.

Left ventricular free wall rupture is a dramatic complication after myocardial infarction. We present our experience with the simple, expedient technique of patch glue repair without extracorporeal circulation. Access is obtained via median sternotomy. Evacuation of blood and haematoma is undertaken and a Goretex patch exceeding the size of infarct is fashioned. The patch is applied to the epicardium using enbrucrilate surgical glue instilled with gentle pressure against the beating heart. We performed this technique on 17 patients from 1993 to 2001, with a operative (30-day) mortality of 23.5% with a post-discharge survival of 85% at 2.2 years.     

Right superficial femoral artery to superior vena cava graft using a polytetrafluroethylene graft: a new technique in a complicated dialysis access patient.

Sir, The expansion of haemodialysis includes older patients withcomorbidities, poor quality vessels, unsuitable for transplantationor peritoneal dialysis. Vascular access complications accountfor 20% of hospital admissions [1]. With exhausted sites inupper extremities, unusual sites for arteriovenous grafts formationare used [2]. The     

Does an oral appliance reduce palatal flutter and tongue base snoring?

OBJECTIVES: Oral appliances are designed to treat snoring and sleep apnea by advancing the mandible and tongue. We test the hypothesis that an oral appliance affects palatal snoring as well as tongue base obstruction. METHODS: Prospective observational cohort study. Sixty patients with a chief complaint of snoring with or without apnea were enrolled. Each patient underwent a home sleep test followed by 3 weeks sleeping with an oral appliance. Each patient then underwent a repeat home sleep test while using the device. RESULTS: There was a statistically significant improvement in the snores per hour (P = 0.0005), the maximum snoring loudness (P = 0.0001), average snoring loudness (P = 0.00001), and the percentage of palatal snoring (P = 0.0007). There was also a significant decrease in oxygen desaturation events (P = 0.003). CONCLUSIONS: This study suggests oral appliances may be effective treatment for both palatal and tongue base snoring.