Investigating the role of prostaglandin signals from adult germ stem cells on somatic aging delay of Caenorhabditis elegans at cold temperatures

Organisms are continuously being challenged by the alterations in environmental conditions. The ability of organisms to detect these alterations and maintain internal integrity is called homeostasis. By the ever-changing environmental conditions, organisms evolutionary also need to distribute their limited energy resources to secure the production of healthy progeny. By the re-allocation of their resources towards generating healthy progeny, resources are less available for the maintenance of soma, leading to a progressive demise of the soma. In these lines, germline removal in many animals is an effective mechanism to promote longevity. Here we challenge this trade-off concept of soma and germline by addressing an intriguing question: how does germline impinge upon aging under favorable conditions? We hypothesize that under such conditions the need for a compromised allocation of resources reduces, thus reproductive capacity can be extended, without a considerable charge on somatic deterioration. Considering lifespan extension as a positive outcome, a moderate reduction in body temperature can induce a significant lifespan extension in distinct animals including C. elegans. Although the pro-longevity effects of reducing body temperature were originally reported over a century ago, little is known about the mechanisms underlying this process. Conventionally, it is thought that longevity results from a passive thermodynamic process. However, discovery of cold-sensitive TRPA-1 channel together with other studies challenge this passive thermodynamic effect of cold temperature on lifespan. In this study, we found that germline-lacking worms have a diminished lifespan at low temperatures when compared with wild-type worms, indicating a role of the germline in cold-induced longevity. Low temperature delays the exhaustion of the germ stem cell (GSC) pool during adulthood, resulting in an extended reproductive capacity. Additionally, we found a role of thermosensory AFD neurons and TRPA-1 channel in maintenance of the GSC pool with age. Notably, cold-induced longevity is blocked by chemical and genetic interventions that impair adult GSC proliferation. Conversely, these interventions do not affect lifespan at higher temperatures. Robust proliferation of adult GSCs induces the expression of CBS-1 in somatic tissues such as the intestine, which leads to the enhanced production of hydrogen sulfide (H2S), a gaseous pro-longevity signaling molecule. Importantly, ectopic expression of cbs-1 in the intestine extends lifespan at standard and warm temperatures. Additionally, we found that GSCs modulate somatic tissues at cold temperatures to induce longevity by production and release of prostaglandin E2 (PGE2). Whereas loss of adult GSCs reduces somatic cbs-1 expression and cold-induced longevity, application of exogenous PGE2 rescues these phenotypes. Taken together, our results indicate that adult GSCs communicate with somatic tissues via prostaglandin signals to extend longevity under favorable environmental and physiological conditions such as cold temperature. This process coordinates extended reproductive capacity and long lifespan under such conditions, without compromising on either the germline or the soma

Association of vitamin D deficiency with COVID-19 severity and mortality in Iranian people: a prospective observational study

Background As the coronavirus disease 2019 (COVID-19) pandemic continues to escalate, it is important to identify the prognostic factors related to increased mortality and disease severity. To assess the possible associations of vitamin D level with disease severity and survival, we studied 248 hospitalized COVID-19 patients in a single center in a prospective observational study from October 2020 to May 2021 in Tehran, Iran. Methods Patients who had a record of their 25-hydroxyvitamin D level measured in the previous year before testing positive with COVID-19 were included. Serum 25-hydroxyvitamin D level was measured upon admission in COVID-19 patients. The associations between clinical outcomes of patients and 25-hydroxyvitamin D level were assessed by adjusting for potential confounders and estimating a multivariate logistic regression model. Results The median (interquartile range) age of patients was 60 years (44–74 years), and 53% were male. The median serum 25-hydroxyvitamin D level prior to admission decreased with increasing COVID-19 severity (P=0.009). Similar findings were obtained when comparing median serum 25-hydroxyvitamin D on admission between moderate and severe patients (P=0.014). A univariate logistic regression model showed that vitamin D deficiency prior to COVID-19 was associated with a significant increase in the odds of mortality (odds ratio, 2.01; P=0.041). The multivariate Cox model showed that vitamin D deficiency on admission was associated with a significant increase in risk for mortality (hazard ratio, 2.35; P=0.019). Conclusions: Based on our results, it is likely that deficient vitamin D status is associated with increased mortality in COVID-19 patients. Thus, evaluating vitamin D level in COVID-19 patients is warranted

Prevalence of Vascular Trauma and Related Factors in Iran: A Systematic Review

Background: Managing patients with Vascular Trauma (VT) is essential. This study aimed todetermine the prevalence of VT and its related factors in Iran.Methods: This systematic review was performed by two skilled researchers. To access all thePersian and English articles on VT and its influencing factors (from 2000 to August 2019),in addition to Google Scholar search engine, other international databases, such as PubMed/Medline, Scopus, Embase, Cochrane Library, Science Direct, Web of Science (ISI), anddomestic databases, such as Magiran, IranDoc, National Library of Iran Organization, SID,and Barakatkns were used. Data analysis was conducted by MA (CMA) software.Results: The incidence of lower Lower Vascular Trauma (LVI) trauma was equal to 58.4(95%CI: 41.1-73.8) (I2= 94.67, Q=112.57, P<0.001); the prevalence of upper LVI trauma wasmeasured to be 31.5 (95%CI: 17.7-49.7) (I2=94.48, Q=108.70, P<0.001); the prevalence ofpenetrating trauma was calculated as 61.3 (95% CI: 49.5-71.9); the prevalence of ulnar nerveinjury equaled 9.8 (95%CI: 2.8-28.6); the prevalence of radial nerve trauma was equal to 7.7(95%CI: 1.2-35.4); the prevalence of death cases was reported as 12.3 (95%CI: 5.1-26.9);the prevalence of amputation rate was observed as 8.8 (95%CI: 5.7-13.4); the prevalenceof fasciotomy rate was equal to 22.2 (95%CI: 13.2-34.5); the prevalence of complete arterycutting equaled 55.7 (95% CI: 35.4-74.3),and the prevalence of incomplete artery cutting wasmeasured as 25.5 (95%CI: 12.1-45.9).Conclusion: According to the study results, VT has led to various complications in patients;thus, it is critical to provide the necessary conditions to preserve the patient’s life and preventlife-threatening complications. Such goals could be achieved by preventing this type of traumaand its related complications

Frequency Characteristics of Multiscale Hybrid Nanocomposite Annular Plate Based on a Halpin–Tsai Homogenization Model with the Aid of GDQM

In this article, we study the vibration performance of multiscale hybrid nanocomposite (MHC) annular plates (MHCAP) resting on Winkler–Pasternak substrates exposed to nonlinear temperature gradients. The matrix material is reinforced with carbon nanotubes (CNTs) or carbon fibers (CF) at the nano- or macroscale, respectively. The annular plate is modeled based on higher-order shear deformation theory (HSDT). We present a modified Halpin–Tsai model to predict the effective properties of the MHCAP. Hamilton’s principle was employed to establish the governing equations of motion, which is finally solved by the generalized differential quadrature method (GDQM). In order to validate the approach, numerical results were compared with available results from the literature. Subsequently, a comprehensive parameter study was carried out to quantify the influence of different parameters such as stiffness of the substrate, patterns of temperature increase, outer temperature, volume fraction and orientation angle of the CFs, weight fraction and distribution patterns of CNTs, outer radius to inner radius ratio, and inner radius to thickness ratio on the response of the plate. The results show that applying a sinusoidal temperature rise and locating more CNTs in the vicinity of the bottom surface yielded the highest natural frequency

Mechanisms of protein homeostasis (proteostasis) maintain stem cell identity in mammalian pluripotent stem cells

Protein homeostasis, or proteostasis, is essential for cell function, development, and organismal viability. The composition of the proteome is adjusted to the specific requirements of a particular cell type and status. Moreover, multiple metabolic and environmental conditions challenge the integrity of the proteome. To maintain the quality of the proteome, the proteostasis network monitors proteins from their synthesis through their degradation. Whereas somatic stem cells lose their ability to maintain proteostasis with age, immortal pluripotent stem cells exhibit a stringent proteostasis network associated with their biological function and intrinsic characteristics. Moreover, growing evidence indicates that enhanced proteostasis mechanisms play a central role in immortality and cell fate decisions of pluripotent stem cells. Here, we will review new insights into the melding fields of proteostasis and pluripotency and their implications for the understanding of organismal development and survival

Technical quality of root canal therapies performed by novice dental students in preclinical practice

Background: For improving the quality of endodontic performance of practitioners in clinical practice, their basic, preclinical performance and knowledge must be taken into consideration. This study aimed to radiographically evaluate the technical quality of preclinical molar root canal treatments (RCTs) performed by undergraduate dental students at a dental school in Iran. Further, the effect of using Gates-Glidden (GG) drills on the final quality of RCTs was evaluated. Materials and Methods: In this retrospective cross-sectional study, 315 roots of 105 endodontically treated teeth in preclinical practice were evaluated radiographically. The analyzed quality parameters included length, taper and density of fillings, which were scored as S2 (adequate standard), the S1 (slight deviation), or S0 (considerable deviation). For all the parameters, acceptable, moderate and poor fillings received total scores of 6, 3-5 and 0-2, respectively. There were two groups of students: One group had used only K-files, and the other had used K-files along with GG drills. The quality of RCTs between these groups was evaluated using the aforementioned scoring protocol. The results were analyzed using Chi-square, Mann-Whitney and Fisher′s exact tests (α = 0.05). Results: Under-fillings (P = 0.001) and under-shapings (P = 0.007) occurred mostly in mandibular root fillings. A lower density was found in maxillary fillings (P < 0.001). No relationship was observed between the technique used (irrespective of GG drills usage) and length (P = 0.499) and taper of fillings (P = 0.238). The roots instrumented with GG drills had a higher filling density (P = 0.004). The quality mean score of RCTs was improved when GG drills were used (P = 0.008). Conclusion: The technical quality of preclinical molar RCTs performed by undergraduate dental students was considered acceptable in 35.6% of the cases. When GG drills were used along with K-files, the technical quality of RCTs was enhanced

Prostaglandin signals from adult germline stem cells delay somatic ageing of Caenorhabditis elegans

A moderate reduction in body temperature can induce a remarkable lifespan extension. Here we examine the link between cold temperature, germline fitness and organismal longevity. We show that low temperature reduces age-associated exhaustion of germline stem cells (GSCs) in Caenorhabditis elegans, a process modulated by thermosensory neurons. Notably, robust self-renewal of adult GSCs delays reproductive ageing and is required for extended lifespan at cold temperatures (10 degrees C, 15 degrees C). These cells release prostaglandin E2 (PGE2) to induce cbs-1 expression in the intestine, increasing the somatic production of hydrogen sulfide, a gaseous signalling molecule that prolongs lifespan. Loss of adult GSCs reduces intestinal cbs-1 expression and cold-induced longevity, whereas application of exogenous PGE2 rescues these phenotypes. Importantly, tissue-specific intestinal overexpression of cbs-1 mimics cold-temperature conditions and extends longevity even at warm temperatures (25 degrees C). Thus, our results indicate that GSCs communicate with somatic tissues to coordinate extended reproductive capacity with longevity

روش EQUAL 2018 برای درجه بندی آسپرژیلوسیس

روش درجه بندی EQUAL برای آسپرژیلوسیس، فاکتورهای مورد نیاز برای جمع آوری و اندازه گیری نحوه ی مدیریت آسپرژیلوس مهاجم حاد ریوی را در اختیار قرار میدهد. روش درجه بندی EQUAL دربرگیرنده ی قویترین توصیه ها بر اساس راهنماهای موجود است. کارت های درجه بندی یک مرجع سریع برای اندازه گیری میزان تبعیت از راهنماها و محافظت در برابر بیماری های قارچی می باشند

روش EQUAL 2018 برای درجه بندی کاندیدا

روش درجه بندی EQUAL برای کاندیدا، فاکتورهای مورد نیاز برای جمع آوری و اندازه گیری نحوه ی مدیریت کاندیدمی را در اختیار قرار میدهد و در واقع به عنوان یک مرجع سریع برای اندازه گیری میزان تبعیت از راهنماها و محافظت در برابر بیماری های قارچی می باشد. راهنماهای موجود بر اساس اطلاعات موجود در انجمن اروپایی میکروبیولوژی بالینی و بیماریهای عفونی4,5 و انجمن بیماریهای عفونی آمریکا3 تهیه شده اند و شامل قویترین توصیه ها برای مدیریت کیفیت بیماری می باشند

روش EQUAL 2018 برای درجه بندی موکورمایکوسیس

روش درجه بندی EQUAL برای موکورمایکوسیس، فاکتورهای مورد نیاز برای جمع آوری و اندازه گیری نحوه ی مدیریت موکورمایکوسیس را در اختیار قرار میدهد. روش درجه بندی EQUAL دربرگیرنده ی قویترین توصیه ها بر اساس راهنماهای موجود است. کارت های درجه بندی یک مرجع سریع برای اندازه گیری میزان تبعیت از راهنماها و محافظت در برابر بیماری های قارچی می باشند