Intravascular source of adenosine during forearm ischemia in humans: implications for reactive hyperemia.

It is believed that adenosine is released in ischemic tissues and contributes to reactive hyperemia. We tested this hypothesis in the human forearm using microdialysis to estimate interstitial and intravascular levels of adenosine and caffeine withdrawal to potentiate endogenous adenosine and determine its effect on reactive hyperemia. Forearm blood flow response to ischemia was measured by air plethysmography before and 60 hours after the last dose of caffeine (250 mg TID for 7 days, n=6). Forearm blood flow increased by 274+/-66% and 467+/-97% after 3 minutes of forearm ischemia, before and during caffeine withdrawal, respectively (P<0.05). Thus, caffeine withdrawal enhances reactive hyperemia. To determine the source of adenosine, we measured interstitial adenosine with the use of a microdialysis probe inserted into the flexor digitorum superficialis muscle of the forearm, and we measured intravascular adenosine with the use of a microdialysis probe inserted retrogradely into the medial cubital vein. Dialysate samples were collected at 15-minute intervals during resting, forearm ischemia, and recovery periods. Forearm ischemia failed to increase muscle dialysate concentrations of adenosine but did increase intravascular dialysate adenosine 2.1-fold, from 0.61+/-0.12 to 1.28+/-0.39 micromol/L (P<0.01, n=8). Intravascular dialysate concentrations of thromboxane B2 did not increase during ischemia, ruling out platelet aggregation as a source of adenosine. These results support the hypothesis that endogenous adenosine contributes to reactive hyperemia and indicate that the major source of adenosine in the human forearm is intravascular. We speculate that endothelial cells are the source of intravascular adenosine during ischemia.     

The Caries Management System: an evidence‐based preventive strategy for dental practitioners. Application for children and adolescents

The application of the Caries Management System (CMS) for children and adolescents follows the rationale underlying the application of the CMS for adults. Briefly, the CMS is a 10‐step, risk‐based, non‐invasive strategy to arrest and remineralize early lesions and to enhance caries primary prevention. The method for assessing each patient’s diet, plaque distribution, and signs of caries as shown in bitewing radiograph images, follows the protocols for adults. Protocols presented here relating to caries risk assessment, lesion diagnosis and management, and patient recall are specific for children and adolescents. Fundamentally, non‐cavitated lesions in primary and especially permanent teeth are managed: (1) professionally by preservative non‐invasive means, including fluoride varnish and sealants; and (2) daily home toothbrushing using fluoride toothpaste where the aim is to arrest lesion progression so that restorations will not be necessary. Monitoring of lesions through the review of clinical signs and bitewing images is the means for assessing caries activity. For those who fail to respond to advice to reduce cariogenic exposures and continue to develop new lesions at a steady or increased rate, a more intensified programme is required; their higher risk status is confirmed and treatment follows the corresponding protocol.     

Disclosure experience and associated factors among HIV positive men and women clinical service users in southwest Ethiopia

Background  

Disclosing HIV test results to one's sexual partner allows the partner to engage in preventive behaviors as well as the access of necessary support for coping with serostatus or illness. It may motivate partners to seek testing or change behavior, and ultimately decrease the transmission of HIV. The present study was undertaken to determine the rate, outcomes and factors associated with HIV positive status disclosure in Southwest Ethiopia among HIV positive service users.     

Distribution of divalent metal transporter 1 and metal transport protein 1 in the normal and Belgrade rat.

Iron accumulation in the brain occurs in a number of neurodegenerative diseases. Two new iron transport proteins have been identified that may help elucidate the mechanism of abnormal iron accumulation. The Divalent Metal Transporter 1 (DMT1), is responsible for iron uptake from the gut and transport from endosomes. The Metal Transport Protein 1 (MTP1) promotes iron export. In this study we determined the cellular and regional expression of these two transporters in the brains of normal adult and Belgrade rats. Belgrade rats have a defect in DMT1 that is associated with lower levels of iron in the brain. In the normal rat, DMT1 expression is highest in neurons in the striatum, cerebellum, thalamus, ependymal cells lining the third ventricle, and vascular cells throughout the brain. The staining in the ependymal cells and endothelial cells suggests that DMT1 has an important role in iron transport into the brain. In Belgrade rats, there is generalized decrease in immunodetectable DMT1 compared to normal rats except in the ependymal cells. This decrease in immunoreactivity, however, was absent on immunoblots. The immunoblot analysis indicates that this protein did not upregulate to compensate for the chronic defect in iron transport. MTP1 staining is found in most brain regions. MTP1 expression in the brain is robust in pyramidal neurons of the cerebral cortex but is not detected in the vascular endothelial cells and ependymal cells. MTP1 staining in Belgrade rats was decreased compared to normal, but similar to DMT1 this decrease was not corroborated by immunoblotting. These results indicate that DMT1 and MTP1 are involved in brain iron transport and this involvement is regionally and cellularly specific.     

Large Low-Field Reversible Magnetocaloric Effect in Itinerant-Electron Hf1−xTaxFe2 Alloys

First-order isostructural magnetoelastic transition with large magnetization difference and controllable thermal hysteresis are highly desirable in the development of high-performance magnetocaloric materials used for energy-efficient and environmental-friendly magnetic refrigeration. Here, we demonstrate large magnetocaloric effect covering the temperature range from 325 K to 245 K in Laves phase Hf_1−xTa_xFe₂ (x = 0.13, 0.14, 0.15, 0.16) alloys undergoing the magnetoelastic transition from antiferromagnetic (AFM) state to ferromagnetic (FM) state on decreasing the temperature. It is shown that with the increase of Ta content, the nature of AFM to FM transition is gradually changed from second-order to first-order. Based on the direct measurements, large reversible adiabatic temperature change (ΔT_ad) values of 2.7 K and 3.4 K have been achieved under a low magnetic field change of 1.5 T in the Hf_0.85Ta_0.15Fe₂ and Hf_0.84Ta_0.16Fe₂ alloys with the first-order magnetoelastic transition, respectively. Such remarkable magnetocaloric response is attributed to the rather low thermal hysteresis upon the transition as these two alloys are close to intermediate composition point of second-order transition converting to first-order transition.     

野生型p53对小鼠纤维肉瘤细胞线粒体功能的影响

目的观察野生型p53(Wtp53)基因对纤维肉瘤细胞线粒体结构和功能的影响, 探讨Wtp53的抑癌机制。方法 将5周龄昆明鼠随机分为单纯肿瘤组(对照组)和Wtp53基因治疗组(治疗组), 建立纤维肉瘤动物模型, 5d后治疗组动物于荷瘤局部注射表达Wtp53基因的重组腺病毒液0.1mL, 对照组同一部位注射等剂量生理盐水。两组动物于2次注射后10d、20d、30d分批处死, 量取肿瘤直径大小, Estabrook法分离提取线粒体, Clark氧电极法进行线粒体呼吸功能的测定, Reer法测定游离Ca²⁺浓度。结果 对照组肿瘤的凋亡指数明显低于治疗组。对照组中R₃显著高于治疗组;10天时两组R₄接近, 但20天和30天时治疗组R₄时相大大延长, 与对照组比较差异非常显著;对照组RCR随着时间的延长无明显变化, 治疗组中, RCR随时间延长而下降明显低于对照组;游离Ca²⁺浓度在10天时与对照组接近, 而后大幅度上升。结论 Wtp53明显降低线粒体呼吸功能, 增加线粒体的通透性, 从而在促进细胞凋亡方面发挥对纤维肉瘤的治疗作用。     

Relative socioeconomic advantage and mood during advanced pregnancy in women in Vietnam

Background  

Mental health during pregnancy has not been investigated in Vietnam. Antenatal depression is an established risk factor for postpartum mood disturbance and two representative cohort studies have found rates of depression after childbirth in Vietnam two to three times higher than those in high income countries.