Prevalence of Thrombocytopenia in the First Week After Burn Injury and Its Relationship With Burn Severity in Shahid Motahari Hospital Over a Period of 6 Months in 2017.

A platelet count of less than 150,000 per microliter of blood is called thrombocytopenia. Platelet count monitoring is essential in the care of burn patients. The aim of this study was to evaluate platelet count in groups of patients with different percentage of burns on the body surface and its relationship with the severity of burns and mortality. This retrospective descriptive cross-sectional study was performed on patients admitted to Shahid Motahari Hospital over a period of six months. The study was conducted on burn patients who were admitted to the hospital on the first day after injury. Patients were divided into two groups of with or without thrombocytopenia in the first week. Demographic information and treatment information about the patients were recorded. SPSS V.26 software was used for the statistical analysis of data. In this study, the prevalence of thrombocytopenia in the first week after burns was 36%. The variables of age, sex, duration of hospitalization, burn agent, percentage of burns and use of silver sulfadiazine ointment were significantly different in the two groups of patients. The group without thrombocytopenia had a mortality rate of 5.1%, while the group with thrombocytopenia had a rate of 32.2%. Based on the results of this study, thrombocytopenia is significantly associated with mortality in burn patients. Furthermore, the results of this study indicate that age, sex, burn agent, percentage of burns, and the use of silver sulfadiazine ointment have a clear impact on the thrombocytopenic status of patients.

La thrombopénie est définie par un compte plaquettaire <150 000/mm3, et la surveillance de la numération plaquettaire (NP) fait partie de la biologie de routine chez les brûlés. Cette étude a pour but l'évaluation de la cinétique de la NP chez des brûlés sur des surfaces variables et sa relation avec la sévérité de la brûlure et la mortalité. Il s'agit d'une étude rétrospective auprès de patients admis dans les 24h suivant leur brûlure dans le CTB de l'hôpital Shahid Motahari durant une période de 6 mois. Nous avons comparé ceux ayant subi une thrombopénie dans la première semaine aux autres (démographie, traitement), les statistiques ayant été réalisées avec SSPS version 26. La prévalence de la thrombopénie précoce est de 36%. Âge, sexe, cause, surface brûlée, recours à la sulfadiazine argentique et durée d'hospitalisation étaient différents entre les deux groupes. La mortalité des patients thrombopénique était de 32,2% VS 5,1%. Elle est significativement associée à la mortalité. L'âge, le sexe, la cause, la surface et la sulfadiazine argentique sont associées à la survenue de thrombopénie.

Comparison of clinicodemographic characteristics and pattern of vascular involvement in 126 patients with Takayasu arteritis: a report from Iran and Turkey.

Takayasu arteritis (TA) is an extremely uncommon vasculitis that primarily affects the aorta and its branches. Due to the genetic and ethnicity effect, a diverse array of TA clinical manifestations has been reported worldwide. The purpose of the present study was to compare the clinicodemographic characteristics and pattern of vascular involvement of Iranian and Turkish TA patients. This study was a retrospective, cross-sectional investigation of 126 TA patients in Iran and Turkey. All of the variables analyzed were extracted from historical medical records. In 126 TA patients, the ratio of females to males was 8.6:1, and the average age at onset of disease was 30.5±11.1 years. Fatigue (49.2%) and a weak or absent pulse (79.4%) were the most prevalent symptoms and signs, respectively. The most prevalent angiographic classifications were types V and I in Iranian patients (41.09%) and type I in the Turkish population (47.7%) The left subclavian artery was the vessel most frequently affected by TA (66.6%). Our findings indicated that there were no significant differences between the two countries in terms of clinicodemographic characteristics or vascular involvement. Some clinical manifestations, such as claudication, were more prevalent in the Turkish population due to a higher incidence of occlusive lesions in the right subclavian artery.

Context Matters: Social Psychological Factors That Underlie Academic Performance across Seven Institutions.

To enhance equity and diversity in undergraduate biology, recent research in biology education focuses on best practices that reduce learning barriers for all students and improve academic performance. However, the majority of current research into student experiences in introductory biology takes place at large, predominantly White institutions. To foster contextual knowledge in biology education research, we harnessed data from a large research coordination network to examine the extent of academic performance gaps based on demographic status across institutional contexts and how two psychological factors, test anxiety and ethnicity stigma consciousness, may mediate performance in introductory biology. We used data from seven institutions across three institution types: 2-year community colleges, 4-year inclusive institutions (based on admissions selectivity; hereafter, inclusive), and 4-year selective institutions (hereafter, selective). In our sample, we did not observe binary gender gaps across institutional contexts, but found that performance gaps based on underrepresented minority status were evident at inclusive and selective 4-year institutions, but not at community colleges. Differences in social psychological factors and their impacts on academic performance varied substantially across institutional contexts. Our findings demonstrate that institutional context can play an important role in the mechanisms underlying performance gaps.

Enzymatic outside-in cross-linking enables single-step microcapsule production for high-throughput three-dimensional cell microaggregate formation.

Cell-laden hydrogel microcapsules enable the high-throughput production of cell aggregates, which are relevant for three-dimensional tissue engineering and drug screening applications. However, current microcapsule production strategies are limited by their throughput, multistep protocols, and limited amount of compatible biomaterials. We here present a single-step process for the controlled microfluidic production of single-core microcapsules using enzymatic outside-in cross-linking of tyramine-conjugated polymers. It was hypothesized that a physically, instead of the conventionally explored biochemically, controlled enzymatic cross-linking process would improve the reproducibility, operational window, and throughput of shell formation. Droplets were flown through a silicone delay line, which allowed for highly controlled diffusion of the enzymatic cross-linking initiator. The microcapsules' cross-linking density and shell thickness is strictly depended on the droplet's retention time in the delay line, which is predictably controlled by flow rate. The here presented hydrogel cross-linking method allows for facile and cytocompatible production of cell-laden microcapsules compatible with the formation and biorthogonal isolation of long-term viable cellular spheroids for tissue engineering and drug screening applications.

Nerve guidance conduit design based on self-rolling tubes.

The current gold standard in peripheral nerve repair is nerve autografts for bridging gaps larger than a centimeter. However, autografts are associated with a low availability and the loss of function at the donor site. Nerve guidance conduits (NGCs) made of biocompatible and biodegradable materials reflect suitable alternatives. Clinically approved NGCs comprise either wraps that are rolled around the loose ends of the nerve or steady-state tubes; however, both lack internal guidance structures. Here, we established self-rolling NGCs to allow for gentle encapsulation of nerve cells together with supportive microenvironments, such as (1) an inner tube wall coating with a bioactive spider silk film, (2) an inner tube wall lining using an anisotropic spider silk non-woven mat, or (3) a luminal filler using an anisotropic collagen cryogel. Neuronal cells adhered and differentiated inside the modified tubes and formed neurites, which were oriented along the guidance structures provided by the spider silk non-woven mat or by the fibrillary structure of the collagen cryogel. Thus, our size-adaptable NGCs provide several features useful for peripheral nerve repair, and distinct combinations of the used elements might support and enhance the clinical outcome.

A 4-Week Model of House Dust Mite (HDM) Induced Allergic Airways Inflammation with Airway Remodeling.

Animal models of allergic airways inflammation are useful tools in studying the pathogenesis of asthma and potential therapeutic interventions. The different allergic airways inflammation models available to date employ varying doses, frequency, duration and types of allergen, which lead to the development of different features of asthma; showing varying degrees of airways inflammation and hyper-responsiveness (AHR) and airways remodeling. Models that also exhibit airway remodeling, a key feature of asthma, in addition to AHR and airway inflammation typically require 5-12 weeks to develop. In this report, we describe a 4-week mouse model of house dust mite (HDM)-induced allergic airways inflammation, and compare the phenotypic features of two different doses of HDM exposures (10 µg and 25 µg) for 5 days/week with a well-characterized 8-week chronic HDM model. We found that 4 weeks of intranasal HDM (25 µg in 35 µl saline; 5 days/week) resulted in AHR, airway inflammation and airway remodeling that were comparable to the 8-week model. We conclude that this new 4-week HDM model is another useful tool in studies of human asthma that offers advantages of shorter duration for development and decreased costs when compared to other models that require longer durations of exposure (5-12 weeks) to develop.

Guidelines on radiographic imaging as part of root canal treatment: a systematic review with a focus on review imaging after treatment.

AIM: To identify guidelines on endodontics which make recommendations relating to post-root canal treatment radiological review imaging, to make an objective assessment of their quality using the AGREE tool and to examine the evidence cited in support of their recommendations. METHODOLOGY: The primary sources to identify published guidelines were MEDLINE (Ovid® ) and EMBASE. The search aim was to identify guidelines pertaining to the post-root canal treatment follow-up recommendations published from 1946 with the final search date being 26 June 2016. The primary search was supplemented by searching Internet search engines and several websites that might have guidelines. The guidelines obtained from the search end-result were assessed for quality and scientific evidence using the AGREE II instrument. Similarities and differences in the recommendations were identified. RESULTS: Thirty guidelines were identified, seven of which met the inclusion criteria. Two guidelines used and clearly described the methods for obtaining scientific evidence from which the recommendations were set. The recommendations varied, particularly as regards the timing of the first review radiograph. Some guidelines lacked supporting evidence. CONCLUSIONS: The recommendations for post-root canal treatment radiographic follow-up varied amongst the identified guidelines. However, the methodology for obtaining the scientific evidence was poorly described in most of the guidelines. Guideline development groups should use the AGREE II instrument as a guide to produce higher quality guidelines.

Comparison of six outcome prediction models in an adult burn population in a developing country.

There are two types of prognostic model - burn-specific and general - to predict mortality risk in burn patients. Most prediction models were devised in developed countries. The aim of this study was to compare the performance of six outcome models in a developing country. In a retrospective cohort study, data of all thermal burned adult patients (age ≥ 18 years) admitted to the Burn Intensive Care Unit (BICU) were collected and then the following six prediction models were used to assess each patient: Acute Physiology and Chronic Health Evaluation (APACHE II), Abbreviated Burn Severity Index (ABSI), Belgian Outcome in Burn Injury (BOBI), the Ryan model, revised Baux and FLAMES model. Discriminative ability and goodness-of-fit of the prediction models were determined by receiver operating characteristic curve analysis and Hosmer-Lemeshow tests. We included 238 patients (mean age: 38.3 ± 18.39 years, average TBSA: 58.27% ± 24.55) in our study; 172 (72.3%) of them were diagnosed with inhalation injury and 178 (72.4%) were intubated. Mortality rate was 69.7%. Deceased patients had significantly higher mean age, %TBSA and number of inhalation injury. The area under the curve of the models was between 64.5 (APACHE II) and 85.9 (ABSI). The best estimation of predicted mortality was obtained with the ABSI model (67.2%).

Des scores de gravité spécifiques ou généraux peuvent être utilisés pour évaluer le pronostic d'un brûlé, la plupart d'entre eux ayant été construits dans des pays développés. Le but de cette étude était de comparer 6 d'entre eux dans un pays en développement. Les données de tous les patients admis en réanimation spécialisée ont été collectées pour calculer 6 scores de gravité qui étaient : APACHE II, ABSI, BOBI, Ryan, Baux révisé et FLAMES. La sensibilité et la spécificité de ces modèles ont été analysées par courbe ROC et test de Hosmer-Lemeshow. Deux cent trente huit patients de 38,3 +/- 18,39 ans, brûlés sur 58,27 +/- 24,55% de SCT ont été inclus. Cent soixante douze (72,3%) avaient inhalé des fumées et 178 (72,4%) avaient été intubés. La mortalité était de 69,7%. Les patients décédés étaient plus âgés, brûlés sur une plus grande surface et avaient plus fréquemment inhalé des fumées. Les aires sous la courbe ROC allaient de 64,5 (APACHE II) à 85,9 (ABSI). Cette étude confirme que l'ABSI reste le meilleur score de gravité pour les patients brûlés.

Impact of cone beam computed tomography (CBCT) on diagnostic thinking in endodontics of posterior teeth: A before- after study.

OBJECTIVES: The aim of this study was to evaluate the impact of limited volume CBCT upon diagnosis as part of endodontic management of posterior teeth. The null hypothesis that CBCT does not make any difference in endodontic diagnosis was tested. METHODS: A single-centre "before-after" study was conducted in a secondary healthcare establishment. Eligible patients were all adults aged 18 years or over who were referred to a specialist endodontic unit. Further inclusion criteria were that the cases were either re-treatment or de novo root canal treatment where the anatomy was judged to be complex. Exclusion criteria included vulnerable groups and de novo endodontic treatment with uncomplicated root canal anatomy. As well as a full history and clinical examination, a high quality colour photographic intraoral image, two paralleling technique periapical radiographs and limited volume CBCT examination were carried out for each patient. All components, except the CBCT dataset, were combined into a Powerpoint presentation and assessed by 4 observers. A questionnaire was designed for the observers as part of the study. RESULTS: CBCT information only changed the radiological findings and the final diagnosis in a minority of cases. There was no clear evidence that CBCT increases the confidence of observers or that CBCT was helpful in making a diagnosis. CONCLUSIONS: Routine use of CBCT cannot not be justified on the basis of a change in diagnosis and carefully selected use is appropriate. CLINICAL SIGNIFICANCE: CBCT is being increasingly used in the field of endodontics. The benefits gained from the use of CBCT must be carefully balanced against the increased radiation dosage. Determination of selection criteria for the use of CBCT in endodontics is, therefore, essential.

Thyroid metastasis of bladder transitional cell carcinoma.

The thyroid gland is a rare site for cancer metastasis. We report a 75-year-old man who was referred with a history of hematuria and generalized bone pain for the past few months. He had a past history of partial left lobe thyroidectomy for follicular adenoma. Subsequently he was referred for a thyroid mass and a subtotal thyroidectomy showed a poorly-differentiated carcinoma. On the latest admission, the patient underwent resection of a bladder tumour with malignant histology and an immunohistochemical profile of CK7+/CK20+/34 Beta E12+/CEA-/PSA-. Re-examination of thyroid sections with immunohistochemical stains revealed the malignant cells to be CK7+/CK20+/34 Beta E12+/CEA-/TTF1-. The findings were compatible with metastasis of the bladder transitional cell carcinoma to the thyroid gland.Scans revealed multiple liver and bone metastases. The patient died 2 months after the diagnosis.

Cyclic mechanical loading promotes bacterial penetration along composite restoration marginal gaps.

OBJECTIVES: Secondary caries is the most common reason for composite restoration replacement and usually forms between dentin and the filling. The objective of this study was to investigate the combined effect of cyclic loading and bacterial exposure on bacterial penetration into gaps at the interface between dentin and resin composite restorative material using a novel bioreactor system and test specimen design. METHODS: Human molars were machined into 3mm thick disks with 2mm deep × 5 mm diameter cavity preparations into which composite restorations were placed. A ∼ 15-30 µm (small) or ∼ 300 µm wide (large) marginal gap was introduced along half of the interface between the dentin and restoration. Streptococcus mutans UA 159 biofilms were grown on each sample prior to testing each in a bioreactor both with and without cyclic loading. Both groups of samples were tested for 2 weeks and post-test biofilm viability was confirmed with a live-dead assay. Samples were fixed, mounted and cross-sectioned to reveal the gaps and observe the depth of bacterial penetration. RESULTS: It was shown that for large gap samples the bacteria easily penetrated to the full depth of the gap independent of loading or non-loading conditions. The results for all cyclically loaded small gap samples show a consistently deep bacterial penetration down 100% of the gap while the average penetration depth was only 67% for the non-loaded samples with only two of six samples reaching 100%. SIGNIFICANCE: A new bioreactor was developed that allows combining cyclic mechanical loading and bacterial exposure of restored teeth for bacterial biofilm and demineralization studies. Cyclic loading was shown to aid bacterial penetration into narrow marginal gaps, which could ultimately promote secondary caries formation.

[New possibilities for ocular surface reconstruction: collagen membranes and biocompatible elastomer nanofibers]. / Neue Möglichkeiten der Augenoberflächenrekonstruktion : Membranen aus Kollagen und biokompatiblen Elastomernanofasern.

BACKGROUND: Amniotic membranes have been used for many years for reconstruction of the ocular surface. Despite having anti-inflammatory and antiangiogenic properties as well as being suitable as a carrier for corneal epithelial cells, amniotic membranes also have some limitations for use at the human cornea: availability is limited, there are major interindividual variations in structure and growth factor content and are not free from the risk of disease transmission. Progress in tissue engineering has been made aiming at the development and improvement of alternative biomaterials. OBJECTIVES: This article presents new approaches for reconstruction of the corneal surface with collagen-based biomaterials and polymers. MATERIAL AND METHODS: Electronic databases were searched for articles which evaluated collagenous biomaterials for use at the corneal surface. In addition the authors' own experiences with novel biomaterials are described. RESULTS: In vitro evaluation of the described biomaterials suggested a high biocompatibility with corneal epithelial cells in cell cultures. In vivo experiments with these materials in animal corneas demonstrated a certain variability in degradation and remodeling. Although some materials showed promising experimental results none of these are established in the clinical routine and only few clinical studies have so far been conducted with collagen-based biomaterials. CONCLUSION: Although the majority of the described biomaterials are currently still in the experimental stage, a transfer into the clinical routine is conceivable and of great therapeutic interest.

[New nanofibrous scaffold for corneal tissue engineering]. / Eine neue Nanofaser-Matrix für den kornealen Gewebeersatz.

BACKGROUND: An estimated 10 million people suffer worldwide from vision loss caused by corneal damage. For the worst cases, the only available treatment is transplantation with human donor corneal tissue. However, in numerous countries there is a considerable shortage of corneal tissue of good quality, leading to various efforts to develop tissue substitutes. The present study aims to introduce a nanofibrous scaffold of poly(glycerol sebacate) PGS as a biodegradable implant, for the corneal tissue engineering. MATERIALS AND METHODS: Nanofibrous scaffolds were produced from PGS and poly(ε-caprolactone) (PCL) by a modified electro-spinning process. The biocompatibility of the material was tested in vitro by colorimetric MTT assay on days 3, 5, and 7 to test the cell viability of human corneal endothelium cells (HCEC). To examine a potential immunological reaction of the scaffolds, samples were exposed to mononuclear cells derived from peripheral blood (PBMCs). After an incubation period of 3 days, supernatants were assayed for apoptotic assessment and immunogenic potentials by annexin V FITC//propidium iodide and flow-cytometric analysis. RESULTS: We could successfully demonstrate that cultivation of HCECs on PGS/PCL scaffolds was possible. Compared to day 3, cell density determined by microplate absorbance was significantly higher after 7 days of cultivation (p < 0.0001). According to the MTT data, none of the samples showed toxicity. Apoptotic assessments by FACS analysis showed that no composition stimulated apoptosis or activated PBMCs occurred. All the compositions were inert for native as well as activated T/B/NK cells and monocytes. It can be concluded that leukocytes and their activity was not affected by the scaffolds. CONCLUSION: A tissue-like scaffold mimicking the human stroma could be developed. The results indicate that PGS/PCL scaffolds could be considered as ideal candidates for corneal tissue engineering as they are biocompatible in contact to corneal endothelial cells and blood cells.

A central role for GRB10 in regulation of islet function in man.

Variants in the growth factor receptor-bound protein 10 (GRB10) gene were in a GWAS meta-analysis associated with reduced glucose-stimulated insulin secretion and increased risk of type 2 diabetes (T2D) if inherited from the father, but inexplicably reduced fasting glucose when inherited from the mother. GRB10 is a negative regulator of insulin signaling and imprinted in a parent-of-origin fashion in different tissues. GRB10 knock-down in human pancreatic islets showed reduced insulin and glucagon secretion, which together with changes in insulin sensitivity may explain the paradoxical reduction of glucose despite a decrease in insulin secretion. Together, these findings suggest that tissue-specific methylation and possibly imprinting of GRB10 can influence glucose metabolism and contribute to T2D pathogenesis. The data also emphasize the need in genetic studies to consider whether risk alleles are inherited from the mother or the father.

Human liver regeneration is characterized by the coordinated expression of distinct microRNA governing cell cycle fate.

In the absence of adequate compensatory regeneration, overwhelming liver damage can cause acute liver failure (ALF) and death without emergent liver transplantation (LT). Auxiliary LT produces satisfactory outcomes in this setting, with the prospect of native liver regeneration sustaining long-term survival. Since animal models only partially recapitulate human liver regeneration, we investigated the molecular mechanisms controlling it in this unique LT setting, as an exemplar of human liver regeneration. We demonstrate coordinated changes in expression of microRNA (miRNA) during regeneration that drive proliferation, innate immunity and angiogenesis. In contrast, failed regeneration in a similar cohort is associated with distinct miRNA enforcing cell cycle inhibition and DNA methylation. The miRNA expression associated with successful or failed regeneration when recapitulated in vitro, triggered expression of cardinal regeneration-linked genes promoting cell cycle entry or inhibition, respectively. Furthermore, inhibition of miRNA 150, 663 and 503, whose downregulation is associated with successful regeneration, induced cell proliferation which a key determinant of successful regeneration. Our data indicate that human liver regeneration may be orchestrated by distinct miRNA controlling key regeneration-linked processes including hepatocyte proliferation. To our knowledge this is the first characterization of molecular processes associated with human liver regeneration.

Comparison of the outcome of burn patients using acute-phase plasma base deficit.

Background. In recent years, plasma base deficit has been used as a marker to determine the status of tissue perfusion in trauma patients and also to predict the outcome of these patients. This study was performed to investigate the effect of plasma base deficit in predicting burn patient outcome. Methods. This prospective cohort study was performed from October 2009 to October 2010 in the acute phase of burn patients who were admitted within 6 h post-injury to Motahari Burn Hospital in Iran. The patients were divided into two groups based on the plasma base deficit in the first 24 h post-injury: group A, in which the mean plasma base deficit was less than or equal to -6 (more negative), and group B, in which the mean plasma base deficit greater than -6. Statistical analysis was performed using SPSS v.16 software. Results. Thirty-eight patients were enrolled in each group. The mean plasma base deficit in group A (-7.76 ± 2.18 mmol) was significantly less than that in group B (-1.19 ± 2.82) mmol (p < 0.05). Although there was no significant difference between the mean of fluid resuscitation and urine output in the first 24 h after injury between the two groups (p > 0.05) and despite removal of interfering factors, there were significant differences between the systemic inflammatory response syndrome and the multiple organ dysfunction syndrome score and the percentage of sepsis between the two groups (p < 0.05). The mortality rate in group A (63.2%) was significantly higher than that in group B (36.8%) (p > 0.05). Conclusion. The plasma base deficit can be used as a valuable marker in the resuscitation of burn patients, along with clinical criteria. Physiological indicators (burn percentage, age, and mucosal burns) are not sufficient to predict mortality and morbidity in burn patients, and it is necessary to investigate the role of biochemical markers such as base deficit in determining the final outcome of burn patients.

Effects of bleaching on mercury ion release from dental amalgam.

The chemical reactions that take place at the amalgam surface when exposed to bleaching agents are not well-understood. It is known, however, that mercury ions are released from dental amalgam when bleached. We hypothesized that increasing concentrations of hydrogen peroxide are more effective than water at increasing mercury ion release from dental amalgam. We prepared dental amalgam discs (n = 65) by packing amalgam into cylindrical plastic molds and divided them into 13 equal groups of 5 discs each. The discs in each group were individually immersed in either 0%, 3.6%, 6%, or 30% (w/v) hydrogen peroxide at exposure periods of 1, 8, 48, and 168 hrs. Samples were taken for mercury ion release determination by inductively coupled plasma mass spectrometry. There were significant increases in mercury release between control and all other hydrogen peroxide concentrations at all exposure times (p < 0.05).

Deletion of the G protein-coupled receptor 30 impairs glucose tolerance, reduces bone growth, increases blood pressure, and eliminates estradiol-stimulated insulin release in female mice.

In vitro studies suggest that the G protein-coupled receptor (GPR) 30 is a functional estrogen receptor. However, the physiological role of GPR30 in vivo is unknown, and it remains to be determined whether GPR30 is an estrogen receptor also in vivo. To this end, we studied the effects of disrupting the GPR30 gene in female and male mice. Female GPR30((-/-)) mice had hyperglycemia and impaired glucose tolerance, reduced body growth, increased blood pressure, and reduced serum IGF-I levels. The reduced growth correlated with a proportional decrease in skeletal development. The elevated blood pressure was associated with an increased vascular resistance manifested as an increased media to lumen ratio of the resistance arteries. The hyperglycemia and impaired glucose tolerance in vivo were associated with decreased insulin expression and release in vivo and in vitro in isolated pancreatic islets. GPR30 is expressed in islets, and GPR30 deletion abolished estradiol-stimulated insulin release both in vivo in ovariectomized adult mice and in vitro in isolated islets. Our findings show that GPR30 is important for several metabolic functions in female mice, including estradiol-stimulated insulin release.

K(ATP)-channels and glucose-regulated glucagon secretion.

Glucagon, secreted by the alpha-cells of the pancreatic islets, is the most important glucose-increasing hormone of the body. The precise regulation of glucagon release remains incompletely defined but has been proposed to involve release of inhibitory factors from neighbouring beta-cells (paracrine control). However, the observation that glucose can regulate glucagon secretion under conditions when insulin secretion does not occur argues that the alpha-cell is also equipped with its own intrinsic (exerted within the alpha-cell itself) glucose sensing. Here we consider the possible mechanisms involved with a focus on ATP-regulated K(+)-channels and changes in alpha-cell membrane potential.

The effect of hydrogen peroxide concentration on metal ion release from dental casting alloys.

There are concerns that tooth bleaching agents may adversely affect dental materials. The aim of this study was to test the hypothesis that increasing concentrations of hydrogen peroxide (HP) are more effective than water at increasing metal ion release from two typical dental casting alloys during bleaching. Discs (n = 28 for each alloy) were prepared by casting and heat treated to simulate a typical porcelain-firing cycle. Discs (n = 7) of each alloy were immersed in either 0%, 3%, 10% or 30% (w/v) HP solutions for 24 h at 37 degrees C. Samples were taken for metal ion release determination using inductively coupled plasma-mass spectrometry and the data analysed using a two-way anova followed by a one-way anova. The surface roughness of each disc was measured using a Talysurf contact profilometer before and after bleaching and the data analysed using a paired t-test. With the exception of gold, the differences in metal ion concentration after treatment with 0% (control) and each of 3%, 10% and 30% HP (w/v) were statistically significant (P < 0.05). Metal ion release from the two alloys increased with increasing HP concentrations (over 3000% increase in Ni and 1400% increase in Pd ions were recorded when HP concentration increased from 0% to 30%). Surface roughness values of the samples before and after bleaching were not significantly different (P > 0.05) Exposure of the two dental casting alloys to HP solutions increased metal ion release of all the elements except gold.