Surgical planning for resection of an ameloblastoma and reconstruction of the mandible using a selective laser sintering 3D biomodel

Ameloblastoma is a benign locally aggressive infiltrative odontogenic lesion. It is characterized by slow growth and painless swelling. The treatment for ameloblastoma varies from curettage to en bloc resection, and the reported recurrence rates after treatment are high; the safety margin of resection is important to avoid recurrence. Advances in technology brought about great benefits in dentistry; a new generation of computed tomography scanners and 3-dimensional images enhance the surgical planning and management of maxillofacial tumors. The development of new prototyping systems provides accurate 3D biomodels on which surgery can be simulated, especially in cases of ameloblastoma, in which the safety margin is important for treatment success. A case of mandibular follicular ameloblastoma is reported where a 3D biomodel was used before and during surgery.     

Root surface conditioning with nicotine or cotinine reduces viability and density of fibroblasts in vitro

The purpose of study was to evaluate fibroblast attachment and cellular morphology on root surfaces chemically conditioned with nicotine or cotinine. A secondary objective was to determine if mechanical scaling and root planning of these chemically conditioned surfaces would alter cellular attachment. Root surface dentin specimens were prepared from uniradicular teeth of non-smoking patients. Specimens were randomly assigned to two experimental groups: no treatment (chemical conditioning only) and scaling and root planning after conditioning (SRPC). The concentrations of the tested substances were in the range of 0–1 mg/mL (nicotine) and 0–1 ?g/mL (cotinine). After a 24-h conditioning period, dentin slices were incubated with continuous lineage of fibroblastic cells from rat (McCoy cells) for another 24 h. Specimens were prepared for SEM analysis and microphotographs. The statistical analysis of the data indicated significant alteration of cellular morphology on fibroblasts that were grown on root surface exposed to nicotine concentrations greater than 1 ?g/mL. This effect of nicotine was not reduced by SRPC. On the other hand, in the SRPC group cellular density was greater. For cotinine-conditioned specimens, the greater concentrations also led to alteration on morphology, and these alterations were observed in the SRPC group as well. Cotinine did not induce significant changes on cellular density. The results indicated that fibroblasts are negatively influenced by nicotine present on the dentin substrate and also that scaling may reduce these effects. Cotinine treatment on root surfaces may alter cell morphology and density but these effects were less severe than that promoted by nicotine, and were not affected by scaling.     

Effect of extracellular K+ on saliva secretion by isolated,perfused rat submandibular glands

Changes in perfusate K⁺ concentration altered the secretory response of the glands to 10^?6 M acetylcholine. Lack of extracellular K⁺ caused a transient fluid secretory response lasting less than 10 min, and a 91 per cent reduction in the overall volume of saliva secreted in 60 min; it inhibited the response to acetylcholine even when the perfusate was changed to K⁺-containing solutions after 30 min. Absence of K⁺ in the perfusate resulted in increased Na⁺ and decreased K⁺ and Cl^? concentrations in saliva. An increase in the perfusate K⁺ concentration to 50 mM/l caused a reduced but more sustained secretory response, although the volume of saliva secreted in 60 min was still reduced by 76 per cent compared to that obtained when the perfusate contained 4.6 m-equiv./l K⁺. Acetylcholine release induced by the high K seemed mostly responsible as the response was inhibited by atropine. However, in the presence of excess of exogenous acetylcholine, perfusion with high K⁺ medium resulted in reduced Na⁺ and elevated K⁺ and Cl^? concentrations in saliva. It seems that a physiological (4–5 m-equiv./l) extracellular K⁺ concentration is required for acinar fluid secretion and for transductal electrolyte transport in the rat glands; lack of external K⁺ hyperpolarizes salivary cells and, although allowing an initial increase in Na⁺ conductance capable of causing secretion, prevents the further influx of this ion required to sustain saliva secretion. It also inhibits K⁺secretion and Na⁺ re-absorption in salivary ducts, probably by inhibiting the Na⁺, K⁺ pump in duct cells; high external K⁺ depolarizes acinar cells and may reduce Na⁺ conductance. It also enhances K⁺ secretion and Na⁺ re-absorption in salivary ducts; the effects of K⁺ omission and of high K⁺ on fluid secretion are likely to be the result of changes in the transmembrane K⁺ gradient in acinar cells and of the way they affect the opening of Na⁺ conductance pathways; perfusion with K⁺-free or high K⁺ solutions reveals a dissociation in ductal reabsorption of Na⁺ and Cl^? and unmasks the presence of independent transport mechanisms for these two ions in salivary ducts.     

Small-diameter implants: indications and contraindications

The choice of implant diameter depends on the type of edentulousness, the volume of the residual bone, the amount of space available for the prosthetic reconstruction, the emergence profile, and the type of occlusion. Small-diameter implants are indicated in specific clinical situations, for example, where there is reduced interradicular bone or a thin alveolar crest, and for the replacement of teeth with small cervical diameter. Before using a small-diameter implant, the biomechanical risk factors must be carefully analyzed. Preliminary reports of this type of implant show good short- and medium-term results.     

In-vitro release of K+ from the developing submandibular gland of early postnatal rats

The release studied by incubating tissue slices in an enriched, oxygenated medium in the presence and absence of secretagogues indicated that slices from 1-day-old rats released K⁺ in response to carbamylcholine, but not in response to epinephrine. The response to carbamylcholine was dose-related, with a 12.6 ± 1.3 per cent release at a concentration of 2 × 10^?5M. Epinephrine did not induce K⁺ release in concentrations from 2 × 10^?7 to 2 × 10^?5M. Glands from 7- and 14-day-old rats released a similar amount as those of new-borns in response to carbamylcholine and by 21 days of age the glands released 21.5 ± 1.9 per cent of their K⁺ content upon exposure to 2 × 10^?5M carbamylcholine. A response to epinephrine (2 × 10^?5M) was first detected at 14 days of age, when the slices released 8.3 ± 1.2 per cent of their K⁺. Slices of 21-day-old rats showed a 17.9 ± 1.3 per cent K⁺ release in response to this dose. As in adult glands, the net amount of K⁺ released by the developing postnatal gland seems to be the result of two opposing mechanisms, a passive efflux and an active re-uptake which depends on the activation of an ouabain-sensitive Na⁺-K⁺ -ATPase. The passive efflux component was similar in glands from different postnatal ages and was enhanced by secretagogues. The extent of active uptake, on the other hand, decreased with increasing postnatal age. As in the adult, the net release of K⁺ depended on the presence of Ca2⁺ in the incubation medium, but the sensitivity of the response to Ca²⁺ omission varied in accord with the age of the animals and with the stimulant used. It is speculated that proacinar and terminal tubular cells may be involved in K⁺ release in the early postnatal period.     

Evolución del cierre de ileostomía en una unidad de cirugía colorrectal. Análisis comparativo según la técnica

Introduction

The objective of this study is to assess whether the results of loop ileostomy closure in terms of morbidity and hospital stay are influenced by the type of anastomosis and suture used.

Method

All patients who underwent loop ileostomy closure were reviewed. A retrospective cohort study comparing morbidity and hospital stay according to the type of anastomosis (TT/LL) and the type of suture (hand sewn/mechanical) was performed.

Results

From January 2003 to November 2011 a total of 167 loop ileostomy closures were analized. The groups were: type of anastomosis (TT 95/LL 72) and type of suture (manual 105/stapled 62). In 76% of the observed population the underlying disease was cancer. Mortality occurred in one case. The stratified morbidity analysis by type of complications showed no significant differences between the groups in terms of local (7.4% TT, LL 8.3%, 6.7% hand sewn, stapled 9.7%), general (TT 9.5%, 16.7% LL, hand sewn 6.7%, 6.5% stapled) and surgical (TT 15.8%, 19.4% LL, hand sewn 17.1%, 17.7% stapled) complications, nor in the rate of reoperations (TT 6.3%, 6.9% LL, hand sewn 6.7%, 6.5% stapled) and hospital stay in days (TT 7.8, 8 LL, hand sewn 8.6, stapled 6.7)

Conclusions

Closure of loop ileostomy can be performed regardless of the type of suture or anastomosis used, with the same rate of morbidity and hospital stay.     

Insulin Resistance and Bone Strength: Findings From the Study of Midlife in the United States

Although several studies have noted increased fracture risk in individuals with type 2 diabetes mellitus (T2DM), the pathophysiologic mechanisms underlying this association are not known. We hypothesize that insulin resistance (the key pathology in T2DM) negatively influences bone remodeling and leads to reduced bone strength. Data for this study came from 717 participants in the Biomarker Project of the Midlife in the United States Study (MIDUS II). The homeostasis model assessment of insulin resistance (HOMA‐IR) was calculated from fasting morning blood glucose and insulin levels. Projected 2D (areal) bone mineral density (BMD) was measured in the lumbar spine and left hip using dual‐energy X‐ray absorptiometry (DXA). Femoral neck axis length and width were measured from the hip DXA scans, and combined with BMD and body weight and height to create composite indices of femoral neck strength relative to load in three different failure modes: compression, bending, and impact. We used multiple linear regressions to examine the relationship between HOMA‐IR and bone strength, adjusted for age, gender, race/ethnicity, menopausal transition stage (in women), and study site. Greater HOMA‐IR was associated with lower values of all three composite indices of femoral neck strength relative to load, but was not associated with BMD in the femoral neck. Every doubling of HOMA‐IR was associated with a 0.34 to 0.40 SD decrement in the strength indices (p < 0.001). On their own, higher levels of fasting insulin (but not of glucose) were independently associated with lower bone strength. Our study confirms that greater insulin resistance is related to lower femoral neck strength relative to load. Further, we note that hyperinsulinemia, rather than hyperglycemia, underlies this relationship. Although cross‐sectional associations do not prove causality, our findings do suggest that insulin resistance and in particular, hyperinsulinemia, may negatively affect bone strength relative to load. © 2014 American Society for Bone and Mineral Research.     

Fundamentals of Endoscopic Surgery cognitive examination: development and validity evidence

Background

Flexible endoscopy is an integral part of surgical care. Exposure to endoscopic procedures varies greatly in surgical training. The Society of American Gastrointestinal and Endoscopic Surgeons has developed the Fundamentals of Endoscopic Surgery (FES), which serves to teach and assess the fundamental knowledge and skills required to practice flexible endoscopy of the gastrointestinal tract. This report describes the validity evidence in the development of the FES cognitive examination.

Methods

Core areas in the practice of gastrointestinal endoscopy were identified through facilitated expert focus groups to establish validity evidence for the test content. Test items then were developed based on the content areas. Prospective enrollment of participants at various levels of training and experience was used for beta testing. Two FES cognitive test versions then were developed based on beta testing data. The Angoff and contrasting group methods were used to determine the passing score. Validity evidence was established through correlation of experience level with examination score.

Results

A total of 220 test items were developed in accordance with the defined test blueprint and formulated into two versions of 120 questions each. The versions were administered randomly to 363 participants. The correlation between test scores and training level was high (r = 0.69), with similar results noted for contrasting groups based on endoscopic rotation and endoscopic procedural experience. Items then were selected for two test forms of 75 items each, and a passing score was established.

Conclusions

The FES cognitive examination is the first test with validity evidence to assess the basic knowledge needed to perform flexible endoscopy. Combined with the hands-on skills examination, this assessment tool is a key component for FES certification.