Low-Frequency Finite-Element Modeling of the Gerbil Middle Ear

The gerbil is a popular species for experimental middle-ear research. The goal of this study is to develop a 3D finite-element model to quantify the mechanics of the gerbil middle ear at low frequencies (up to about 1 kHz). The 3D reconstruction is based on a magnetic resonance imaging dataset with a voxel size of about 45 μm, and an x-ray micro-CT dataset with a voxel size of about 5.5 μm, supplemented by histological images. The eardrum model is based on moiré shape measurements. Each individual structure in the model was assumed to be homogeneous with isotropic, linear, and elastic material properties derived from a priori estimates in the literature. The behavior of the finite-element model in response to a uniform acoustic pressure on the eardrum of 1 Pa is analyzed. Sensitivity tests are done to evaluate the significance of the various parameters in the finite-element model. The Young’s modulus and the thickness of the pars tensa have the most significant effect on the load transfer between the eardrum and the ossicles and, along with the Young’s modulus of the pedicle and stapedial annular ligament, on the displacements of the stapes. Overall, the model demonstrates good agreement with low-frequency experimental data. For example, (1) the maximum footplate displacement is about 35 nm; (2) the umbo/stapes displacement ratio is found to be about 3.5; (3) the motion of the stapes is predominantly piston-like; and (4) the displacement pattern of the eardrum shows two points of maximum displacement, one in the posterior region and one in the anterior region. The effects of removing or stiffening the ligaments are comparable to those observed experimentally.     

Chitosan as a Novel Nasal Delivery System for Peptide Drugs

A nasal solution formulation of the cationic material chitosan was shown to greatly enhance the absorption of insulin across the nasal mucosa of rat and sheep. The absorption promoting effect was concentration dependent with the optimal efficacy obtained for concentrations higher than 0.2% and 0.5% in rats and sheep, respectively. The absorption promoting effect was reversible with time in a pulse-chase study. Histological examination of the nasal mucosa of rats exposed to a chitosan solution for 60 minutes showed little change.     

Hypercholesterolemia is a Potential Risk Factor for Asthma

Introduction. The effect of hyperlipidemia on asthma has never been addressed. Recent literature implicates a pro-inflammatory role for hypercholesterolemia. This study evaluates the effect of serum cholesterol level on asthma frequency. Methods. Factors associated with asthma risk were examined in a retrospective study design. Study subjects were between the 4 and 20 years of age who presented to a rural pediatric clinic and whose total serum cholesterol level was obtained. Diagnosis of asthma was determined by the treating physician. Multivariable logistic regression was performed to identify variables that were related to the odds of having asthma. Results. A total of 188 patients were included. Asthma was present in 50 patients. Total serum cholesterol (mean ± SD) for the asthma group was 176.7 ± 39.8 compared to 162.9 ± 12.8 in the non-asthma group (P = 0.028). A total of 21 of the 50 (42%) asthma patients were obese compared to 31 of the 138 (22%) non-asthma patients (p = 0.014). There was no difference between both groups regarding age and gender. Hypercholesterolemia and obesity were identified by logistic regression analysis to increase the probability of asthma independently. Conclusion. Hypercholesterolemia is a potential risk factor for asthma independent of obesity.     

After Laparoscopic Heller Myotomy,Do Emergency Department Visits or Readmissions Predict Poor Long-Term Outcomes?

Introduction  Laparoscopic Heller myotomy is a first-line treatment for achalasia. To improve outcomes after myotomy and to determine if poor early results predict later outcomes, emergency department (ED) visits and readmissions within 60 days following laparoscopic Heller myotomy were studied. Materials and Methods  Since 1992, 352 patients have undergone laparoscopic Heller myotomy and are followed through a prospectively maintained registry. Causes of ED visits and readmissions within 60 days after myotomy were determined. Patients scored their symptoms of achalasia before myotomy and at last follow-up; scores were compared to determine if the reasons leading to ED visits and/or readmissions impacted long-term outcome after myotomy. Results  Fourteen (4%) patients had ED visits, and 18 (5%) patients had readmissions within 60 days following myotomy. Sixty-four percent of ED visits were for dysphagia/vomiting and 36% were for abdominal/chest pain, while 37% of readmissions were for dysphagia/vomiting. Pneumonia was complicated by empyema in four patients, all without leaks; two patients expired. Despite ED visits/readmissions, achalasia symptom (e.g., dysphagia, regurgitation, choking, heartburn, and chest pain) frequency and severity scores improved after myotomy (p < 0.05 for all). Conclusions  ED visits and readmissions are infrequent following laparoscopic Heller myotomy. ED visits were generally due to complaints related to achalasia or edema after myotomy, while readmissions were generally related to complications of operative intervention or chronic ill health. Despite ED visits or readmissions early after myotomy, symptoms of achalasia are well palliated by myotomy long-term. Presented at the Society for Surgery of the Alimentary Tract 48th Annual Meeting, Washington, DC, May 19–24, 2007.     

Thoracoscopic treatment of pulmonary hydatid cyst in a child

Hydatid disease has a wide geographic distribution around the world. In human, the lungs are the second most commonly affected sites. Pulmonary hydatidosis is much more frequently encountered in children than in adults. Surgical treatment has remained the standard option in the management of hydatid disease. However, surgeons were able to replicate the principles of conventional surgery using minimally invasive techniques. Herein, we report a case of pulmonary hydatid cyst in a 9-year-old girl treated successfully using the thoracoscopic approach.     

Quantification of mitochondrial sublimons in human fibrillating atria

Supraventricular tachycardias, including AF (atrial fibrillation), and mtDNA (mitochondrial DNA) deletions may lead to dilated cardiomyopathy. It is unknown whether mtDNA function is impaired in the human atrium in AF. In the present study, we investigated the role of rearranged mtDNA 'sublimons' in the pathogenesis of AF. Right atrial biopsies were collected from 38 patients in AF and 35 patients with SR (sinus rhythm) undergoing elective cardiac surgery. Total DNA was extracted by standard methods. The break-point regions of the two most prevalent classes of sublimon were amplified by PCR using fluorescent oligonucleotides for the 3.75 kb partial duplication and the 2.83 kb deletion. Multiplex reactions included additional primers to amplify an internal genomic standard for semi-quantitative analysis. Reaction products were quantified as peak areas in the electrophoretogram and ratios computed of the sublimon abundance relative to the genomic standard. There was no difference in SCN (sublimon copy number) between AF and SR patients [19.09+/-28.29 compared with 10.25+/-24.68, the difference was 0.28 (95% confidence interval, -0.04 and +0.61; P =0.08)]. SCN did not increase with age ( P =0.207) and was unrelated to AF duration ( P =0.661), left atrial diameter ( P =0.560), post-operative AF ( P =0.52), underlying disease ( P =0.94), medication and gender (2.84+/-0.72 in females vs 2.97+/-0.67 in males; P =0.431). In conclusion, our findings do not indicate any role of mtDNA in the pathophysiology of AF.     

Intravenous antidepressants: a review

Antidepressant medications have an onset of action of several weeks and have moderate efficacy. Their mode of administration is oral (p.o.). Some clinicians wondered whether intravenous (i.v.) administration would speed onset of action and increase efficacy. In this article we review controlled studies on i.v. administration of antidepressants. These include clomipramine, citalopram, and other antidepressants. Overall these studies do not support increased efficacy of i.v. over p.o.administration but there are suggestions of a faster onset of action. In one study i.v. citalopram showed superior response rates over p.o. citalopram (79% vs. 63%) in severely depressed patients at 8 weeks.     

Surgery versus pharmacotherapy of benign thyroid diseases

Surgical management of benign thyroid diseases (BTDs) has been a topic of interest and confusion for many years. Almost 80% of thyroidectomies at an average endocrine surgical unit are carried out for BTDs. Resistance to surgical intervention in BTDs has been based on the belief that increased complication rate is inherent in its use, this is despite the potential advantages in terms of confirming the benign nature of the lesion, controlling the disease, and relieving local symptoms of large neck mass. Benign thyroid diseases are more likely to occur in middle-aged women living in iodine deficient areas, or have a family history of goiter, or in patients taking iodine-containing drugs, like amoidarone, or in patients with previous history of x-ray exposure. However, the physician must be careful in making the diagnosis of BTDs in patients at the extremes of age or in the presence of positive history of radiation, or in patients with family history of thyroid or colon cancer. In this article we will review the etiology, epidemiology, diagnostic methodologies and the recent trends in the surgical and medical management of BTDs.     

Does Barrett's esophagus impact outcome after laparoscopic Nissen fundoplication?

BACKGROUND: This study was undertaken to compare patients with gastroesophageal reflux disease (GERD) with or without Barrett's esophagus for severity and frequency of symptoms and their response to antireflux surgery. METHODS: Eighty patients with GERD and Barrett's esophagus and 93 concurrent patients with GERD alone, all of whom underwent laparoscopic Nissen fundoplication, were compared by using symptom scores graded by a Likert scale. RESULTS: Before fundoplication, patients with Barrett's esophagus had higher DeMeester scores. Symptom scores were not different for patients with versus without Barrett's esophagus before or after laparoscopic Nissen fundoplication. CONCLUSIONS: Before and after fundoplication, patients with Barrett's esophagus, despite more severe reflux, have symptoms nearly identical in frequency and severity when compared with patients with GERD alone. Regardless of presence of Barrett's, all improve dramatically with laparoscopic Nissen fundoplication. Barrett's esophagus does not impact presentation before or outcome after laparoscopic Nissen fundoplication.