A multi-scale computational assessment of channel gating assumptions within the Meissner corpuscle.

From the macroscopic mechanical deformation of skin to the feeling of touch is a chain of complex events whereby information is converted from one form to another between different scales. An important link in this chain is receptor activation, which requires incorporation of microanatomical, cellular and ion channel transduction models. Of particular interest is the deformations at the axon membrane bi-layer, which are believed to be involved in mechanoelectrical signal transduction by activation of ion channels. We present a fully coupled multi-scale finite element analysis of the finger pad during tactile exploration, whereby the Meissner corpuscle, which is modeled as a single representative volume element (RVE) at the microscopic level, interacts with the macroscopic finger model. Maximum values of local stretching and compression occurring at the bi-layer are monitored for finger models with and without fingerprints, the presence of which generates a remarkable amplification of the signal. The contours of the surface being explored are well represented by the maximal peaks observed within the membrane.

Cataract surgery in patients with Fuchs' heterochromic iridocyclitis.

PURPOSE: To evaluate the results of cataract extraction and posterior chamber intraocular lens (IOL) implantation in patients with Fuchs' heterochromic iridocyclitis (FHI). METHODS: We studied the records of 35 patients with FHI who underwent cataract extraction. Extracapsular cataract extraction (ECCE) was performed by phacoemulsification through a scleral flap in 9 patients and by manual delivery of the nucleus through a corneal section in 26 patients. RESULTS: After a mean follow-up time of 24 (3-60) months, the visual acuity in 21 eyes (60%) was 20/20, and all eyes had 20/40 or better vision. Six eyes with implanted regular PMMA IOL developed a marked anterior uveitis, which was resolved within 3 weeks with topical steroids. Only 1+ or 2+ cellular reaction was observed postoperatively in patients with heparin-coated lens implantation and patients who underwent phacoemulsification. Biomicroscopic evidence of giant cell activity was observed in two patients with heparin-coated IOL and in 11 with regular PMMA IOLs after ECCE (two after phacoemulsification). Four eyes developed intraocular pressure elevation that reverts to normal within 24 weeks with medical therapy. CONCLUSIONS: These results indicate that the surgical outcomes of FHI patients after cataract surgery appear to be better when the phacoemulsification technique is used or when heparin-coated lenses are implanted.

Emmetropization, visual acuity, and strabismus outcomes among hyperopic infants followed with partial hyperopic corrections given in accordance with dynamic retinoscopy.

OBJECT: To record emmetropization, visual acuity, and strabismus outcomes among hyperopic infants followed with partial hyperopic corrections given in accordance with dynamic retinoscopy (DR). METHODS: Infants (3.5-12 months of age) with ≥5 D hyperopia were followed without glasses or partial hyperopic corrections prescribed according to their near dynamic accommodative abilities determined by DR responses at the initial visit and follow-ups. Refraction and binocular accommodative ability assessments were made at 3-month intervals up to the age of 1 and at 6-month intervals afterwards for a mean 35.4±2.1 months; main outcome measures being the development of esotropia, emmetropization rate, and visual acuity level after emmetropization period. RESULTS: Among 211, 146 were normal accommodators initially (Group 1). These infants were followed without treatment and none presented with strabismus. Sixty-five infants were hypo-accommodators (Group 2) and received minimum DR-based corrections. Of the 65 infants 31 (48%) developed strabismus (Group 2B). The remaining 34 constituted Group 2A. Each of the three groups showed an overall reduction of hyperopia by 0.37±0.25 days per year, 0.50±0.28 days per year, and 0.60±0.20 days per year, respectively. Visual acuity assessments among Groups 1 and 2A revealed normal values (0.2-0.0 LogMAR); among Group 2B 19% were within normal range. CONCLUSIONS: Binocular accommodative behavior at the initial visit seems to be one of the indicators for pointing out infants at risk of developing strabismus and amblyopia. Prescription of DR-based corrections to hyperopic orthotropic infants does not impede emmetropization and result in normal visual acuities after emmetropization period.

Clinical appointment process: improvement through schedule defragmentation.

Most clinics rely on the appointment scheduling systems to manage patients' access to their health-care providers. Conventional appointment scheduling processes have intrinsic inefficiency because of the tendency to generate fragmented time slots. In this article, a solution, which considers patient-provider mutual preference, is provided to guide the appointment scheduling process by means of schedule defragmentation. Computer simulation shows that patient-provider cooperation can effectively reduce schedule fragmentation, yielding higher appointment acceptance rate and clinic time utilization rate at given appointment demand matched by service supply. When service time distribution can be accurately estimated, decreasing unit time slot size may further improve the appointment scheduling efficiency. In addition, a clinical survey was conducted to identify the opportunities and challenges of applying the proposed defragmentation method in clinical appointment scheduling practice.

Acute scrotal pain in children--ten years' experience.

INTRODUCTION: Acute scrotal pain sometimes requires prompt surgical intervention and therefore accurate diagnosis of different etiologies of acute scrotal pain has great therapeutical and prognostic significance. The aim of this study was to analyze the incidence, symptomatology and results of treatment of acute scrotal pain in children. MATERIAL AND METHOD: The study included patients hospitalized at the Pediatric Surgery Clinic with a diagnosis of acute scrotal pain. We retrospectively analyzed anamnestic data (age of patient and duration of anamnesis prior to admission), clinical parameters obtained during physical examination, mode of treatment (operative or medical), intraoperative findings and (postoperative) treatment. RESULTS: The study included 256 patients with acute scrotal pain, aged from several hours up to 17 years of age (average 9.73 years). The average duration of symptoms prior to admission was 56.74 h. Acute epididymitis was diagnosed in 110 patients (43.0%), torsion of the testicular appendage in 104 patients (40.6%), torsion of the testis in 30 patients (11.7%) and other pathologies in another 12 patients. 166 patients (64.8%) underwent surgery, 42 patients with orchiepididymitis (38.2%), 92 patients with torsion of the testicular appendage (88.5%), and 16.6% of the patients with other pathologies. 22 patients with torsion of the testis underwent surgery (73.3%), while the rest of the 8 patients underwent manual detorquation of the testis. CONCLUSION: Regardless of the etiology of the acute scrotal pain, it is of great importance that the patient seeks medical assistance promptly. It is therefore important to educate the parents and patients about the problems related to acute scrotal pain.

Impact of oxygenator design on hemolysis, shear stress, and white blood cell and platelet counts.

OBJECTIVE: To determine whether relative pressure drop, shear stress, hemolysis, and white blood cell and platelet counts are influenced by different oxygenator designs. To compare the oxygenator results with the average shear stress over an arterial cannula. DESIGN: Prospective; patients enrolled consecutively. SETTING: University hospital. PARTICIPANTS: Three groups of 12 adults patients, scheduled for routine cardiac surgery. INTERVENTIONS: Each group was submitted to a different oxygenator design: group 1 to a high-pressure hollow-fiber membrane oxygenator (Sarns Turbo); group 2 to a medium-pressure hollow-fiber membrane oxygenator (Cobe optima); and group 3 to a flat-sheet membrane oxygenator (Cobe Duo). MEASUREMENTS AND MAIN RESULTS: Although the investigated oxygenators have important differences in pressure drop and shear stress, no statistical differences were found in hemolysis generation or blood handling among the different groups. Actually, the study shows much higher shear stress levels over an average arterial cannula than over any of the evaluated oxygenators. CONCLUSIONS: The pressure drop over an oxygenator does not correlate well with shear stress and hemolysis because the dimensions of the system (radius and length) must be included in the calculation of shear stress from pressure drop.