Thyroid dysfunction after mantle irradiation of Hodgkin's disease patients

Thyroid dysfunction can develop in patients with Hodgkin's disease who are treated with mantle irradiation. During the period 1970-89, the records of 320 patients who received mantle irradiation and who had thyroid function tests (TFT) were retrospectively reviewed. The median age was 30 years (range, 7-69 years). The median mantle and thyroid dose was 36 Gy (range, 30-40 Gy) and 39.8 Gy (range, 32-65 Gy), respectively. Overall thyroid dysfunction was present in 39% of the patients. Clinical hypothyroidism was seen in 10% and biochemical hypothyroidism was noted in 25%. Hyperthyroidism was found in 4% of patients. Thyroid nodules had developed in six patients (2%), of which those in four patients were malignant. Age, sex, histological subtype, stage of disease, dose, lymphangiogram and treatment with chemotherapy were not significant factors in the development of thyroid dysfunction. The narrow dose range prevented adequate analysis of dose effect. The results indicate that the incidence of thyroid abnormalities is high enough to warrant regular TFT assessment with pre-irradiation levels and follow-up testing for life because the development of abnormalities can occur many years later. Thyroid examination should form part of the routine follow-up examination and any abnormality should be promptly investigated.     

Identification of Candida species in the clinical laboratory: a review of conventional,commercial, and molecular techniques

In healthy individuals, Candida species are considered commensal yeasts of the oral cavity. However, these microorganisms can also act as opportunist pathogens, particularly the so‐called non‐albicans Candida species that are increasingly recognized as important agents of human infection. Several surveys have documented increased rates of C. glabrata, C. tropicalis, C. guilliermondii, C. dubliniensis, C. parapsilosis, and C. krusei in local and systemic fungal infections. Some of these species are resistant to antifungal agents. Consequently, rapid and correct identification of species can play an important role in the management of candidiasis. Conventional methods for identification of Candida species are based on morphological and physiological attributes. However, accurate identification of all isolates from clinical samples is often complex and time‐consuming. Hence, several manual and automated rapid commercial systems for identifying these organisms have been developed, some of which may have significant sensitivity issues. To overcome these limitations, newer molecular typing techniques have been developed that allow accurate and rapid identification of Candida species. This study reviewed the current state of identification methods for yeasts, particularly Candida species.     

Functional assembly and purinergic activation of bestrophins

Proteins of the bestrophin family produce Ca²⁺-activated Cl⁻ currents and regulate voltage-gated Ca²⁺ channels. Bestrophin 1 was first identified in the retinal pigment epithelium. Four human paralogs (hBest1–hBest4) exist, and for some bestrophins, dimeric and heterotetrameric structures have been proposed. Here, we demonstrate that hBest1–hBest4 induce Cl⁻ conductances of different amplitudes when expressed in HEK293 cells and when activated through purinergic stimulation. hBest1 mutants that are known to cause autosomal dominant macular dystrophy (Best disease) did not produce a Cl⁻ current. Bestrophins were colocalized and showed molecular and functional interaction in HEK293 cells, overexpressing hBest1 and hBest2 or hBest4. Interaction was confirmed in airway epithelial cells coexpressing endogenous bestrophins. A fraction of hBest2 and hBest4 was expressed in the membrane, while most of hBest1 was found in the endoplasmic reticulum. Nevertheless, hBest1 has a clear role for the adenosine triphosphate (ATP; or uridine triphosphate)-induced Cl⁻ current in both HEK293 and Calu-3 cells. Since native epithelial tissues typically express several bestrophin paralogs, these proteins may exist as heterooligomeric structures. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

胫股关节吻合性对人工膝关节聚乙烯磨损的影响

人工关节置换术是矫正关节畸形、解除关节疼痛、重建关节功能的主要手段。多年来 ,人工全髋、全膝皆以聚乙烯为关节形成表面 ,随着人工关节置换的广泛开展 ,聚乙烯磨损问题越来越引起人们的关注。聚乙烯磨损及其产生的碎屑和磨损颗粒所引发的生物学反应及导致的骨吸收、骨溶解 ,是造成假体松动、人工关节翻修的主要原因[1,2 ] 。与人工髋关节的球洞几何形态相比 ,人工膝关节的几何形态要不吻合的多 ,胫骨假体表面常承受较大的接触应力 ,较易产生磨损[2 ,3 ] ,理论上关节形成表面越吻合 ,聚乙烯磨损越少 ,不同的胫股关节吻合性 ,对假体磨损产…     

Dental fear and pain: effect on patient''s perception of the dentist

A questionnaire was developed including the Dental Anxiety Scale (DAS) and the Dental Beliefs Survey (DBS) as subscales to examine the epidemiology of dental fear and dental beliefs in Germany. The survey was administered before treatment to a sample of 474 dental patients. Of the respondents 56% were female. The mean age was 34.3 yr (SD 12.4 yr). The mean DAS score was 8.6 (SD 3.7). Mean DBS score ranged from 1.73 to 2.75 for single items. The correlation between DAS and DBS scores was highly significant (rs = 0.39, P less than 0.001). Absence or presence of dental pain revealed significant differences for DAS and DBS scores (P less than 0.001). Both tests are valid screening forms for the German linguistic context and easy to implement in daily dental routine.     

The amiloride-inhibitable Na+ conductance is reduced by the cystic fibrosis transmembrane conductance regulator in normal but not in cystic fibrosis airways.

Cystic fibrosis (CF) airway cells, besides their well-known defect in cAMP-dependent Cl- conductance, are characterized by an enhanced Na+ conductance. In this study we have examined the Na+ conductance in human respiratory tract by measuring transepithelial voltage and resistance (Vte, Rte) and by assessing membrane voltages (Vm) of freshly isolated airway epithelial cells from CF and non-CF patients. Basal amiloride inhibitable (10 micromol/liter) equivalent short circuit current (Isc = Vte/Rte) was significantly increased in CF compared with non-CF tissues. After stimulation by forskolin (10 micromol/liter) a significant depolarization of Vm corresponding to the cAMP-dependent activation of a Cl- conductance was observed in non-CF but not in CF airway cells. In non-CF tissue but not in CF tissue the effects of amiloride and N-methyl-D-glucamine on Vm were attenuated in the presence of forskolin. Also the amiloride-inhibitable Isc was significantly reduced by forskolin (1 micromol/liter) and isobutylmethylxanthine (IBMX; 100 micromol/liter) only in non-CF tissue. We conclude that cystic fibrosis transmembrane conductance regulator acts as a downregulator of epithelial Na+ channels in human airways. This downregulation of epithelial Na+ channels is absent in CF airways, leading to hyperabsorption and to the characteristic increase in mucus viscosity.     

Bestrophin 1 is indispensable for volume regulation in human retinal pigment epithelium cells

In response to cell swelling, volume-regulated anion channels (VRACs) participate in a process known as regulatory volume decrease (RVD). Only recently, first insight into the molecular identity of mammalian VRACs was obtained by the discovery of the leucine-rich repeats containing 8A (LRRC8A) gene. Here, we show that bestrophin 1 (BEST1) but not LRRC8A is crucial for volume regulation in human retinal pigment epithelium (RPE) cells. Whole-cell patch-clamp recordings in RPE derived from human-induced pluripotent stem cells (hiPSC) exhibit an outwardly rectifying chloride current with characteristic functional properties of VRACs. This current is severely reduced in hiPSC-RPE cells derived from macular dystrophy patients with pathologic BEST1 mutations. Disruption of the orthologous mouse gene (Best1^−/−) does not result in obvious retinal pathology but leads to a severe subfertility phenotype in agreement with minor endogenous expression of Best1 in murine RPE but highly abundant expression in mouse testis. Sperm from Best1^−/− mice showed reduced motility and abnormal sperm morphology, indicating an inability in RVD. Together, our data suggest that the molecular identity of VRACs is more complex—that is, instead of a single ubiquitous channel, VRACs could be formed by cell type- or tissue-specific subunit composition. Our findings provide the basis to further examine VRAC diversity in normal and diseased cell physiology, which is key to exploring novel therapeutic approaches in VRAC-associated pathologies.Tight regulation of cell volume is fundamental to proper cell function and survival. In general, rapid water influx across cell membranes leads to cell swelling, which in turn activates net efflux of K⁺ and Cl⁻, thereby triggering the release of osmotically obligated water from the cell. Essential to this process is the activation of a current primarily carried by chloride ions (I_swell). This current is gated by volume-regulated anion channels (VRACs) returning the cell to a controlled state of homeostatic integrity, a complex mechanism commonly referred to as regulatory volume decrease (RVD) (1, 2). Although VRACs share common features in almost all cell types, it is unclear whether there is one ubiquitous channel or a diversity of chloride channels with slightly differing functional properties. In this context, three families of proteins—the Ca²⁺- and/or volume-sensitive anoctamins, bestrophins, and the recently discovered LRRC8s—are presently at the center of interest (3–7).Bestrophin 1 (BEST1), a member of the human bestrophin family of four paralogous genes, encodes an integral membrane protein strongly expressed in the human retinal pigment epithelium (RPE) (8). Mutations in BEST1 have been associated with various macular dystrophies most prominently represented by Best disease (BD), a central retinopathy with autosomal dominant inheritance but variable penetrance and expressivity (9, 10). Key features of BD pathology include a striking lipofuscin accumulation in the macular RPE (11) and an abnormal light peak (LP)/dark trough ratio in the electro-oculogram (EOG) reflective of an impaired RPE (12). The abnormalities in the LP were suggested to be compatible with a function of BEST1 as a Ca²⁺-activated Cl⁻ channel (CaCC) (13, 14).Addressing BEST1 function, several studies have suggested a role of the protein in distinct basic cellular processes such as Ca²⁺ homeostasis, neurotransmitter release, and cell volume regulation. These studies mostly relied on BEST1 overexpression in HEK293 cells or conducted in vitro experiments with isolated cells from existing Best1-deficient mouse lines. In summarizing these data, BEST1 was shown to be (i) a calcium sensor localized to the endoplasmic reticulum (ER) of mouse RPE (15), (ii) an intracellular Cl⁻ channel activating anoctamin 1 (ANO1) located at the plasma membrane of mouse trachea (5), (iii) a modulator of voltage-gated Ca²⁺ channels in murine RPE (16), and (iv) a channel for tonic GABA or slow glutamate release in mouse glia cells and astrocytes (17, 18). To date, the functional role of Best1 has not been determined in the mouse testis, the site of highest endogenous Best1 expression in the mouse (19). In addition, using patient-derived hiRPE cells, the role of BEST1 in mediating ER calcium release and/or uptake was shown (20). In contrast, two independent studies in S2R+ cells from Drosophila melanogaster strongly suggested the invertebrate Drosophila Best1 (dBest1) to act as a volume-regulated chloride channel but with biophysical characteristics clearly distinct from a vertebrate VRAC (3, 21). By small interfering RNA (siRNA)-mediated knockdown of BEST1 in HEK293 cells (6) and mouse Best1 (mBest1) gene disruption in murine peritoneal macrophages (22), two studies could not show a functional effect of BEST1 on I_swell, thus questioning this protein as a candidate for mammalian VRAC in these cell types. Instead, two studies identified the LRRC8A gene as an essential component of a VRAC in various cultured cell lines (6, 7). In these latter studies, the authors propose a scenario where LRRC8A and the isoforms LRRC8B to LRRC8E form variable cell type-specific hexamers, explaining the variability of VRAC properties in different cell types.Together, the rather disparate reports on BEST 1 function underscore the need to further clarify its role in mammalian VRACs. To this end, we focused on two tissues with strong endogenous BEST1 protein expression—namely, human RPE (8) and mouse sperm (19). Major insight into BEST1 function was gained from (i) RPE cell culture models established via hiPSC technology from a healthy donor and two macular dystrophy patients with established pathologic mutations in BEST1 and (ii) a mouse strain deficient for Best1, the murine ortholog of the human BEST1 gene. When exposed to hypo-osmotic challenge, both the mutant hiPSC-RPE cells and Best1-deficient mouse spermatozoa exhibited severe phenotypes, suggesting BEST1 as a crucial component of VRAC function in these cell types. In addition, membrane rupture experiments and voltage-clamp recordings in oocytes from Xenopus laevis, coexpressing aquaporin-1 (AQP1) and BEST1 from mouse and human, respectively, demonstrated identical functional properties of the mammalian BEST1 orthologs.