Renal telocytes contribute to the repair of ischemically injured renal tubules

Telocytes (TCs), a distinct type of interstitial cells, have been identified in many organs via electron microscopy. However, their precise function in organ regeneration remains unknown. This study investigated the paracrine effect of renal TCs on renal tubular epithelial cells (TECs) in vitro, the regenerative function of renal TCs in renal tubules after ischaemia–reperfusion injury (IRI) in vivo and the possible mechanisms involved. In a renal IRI model, transplantation of renal TCs was found to decrease serum creatinine and blood urea nitrogen (BUN) levels, while renal fibroblasts exerted no such effect. The results of histological injury assessments and the expression levels of cleaved caspase‐3 were consistent with a change in kidney function. Our data suggest that the protective effect of TCs against IRI occurs via inflammation‐independent mechanisms in vivo. Furthermore, we found that renal TCs could not directly promote the proliferation and anti‐apoptosis properties of TECs in vitro. TCs did not display any advantage in paracrine growth factor secretion in vitro compared with renal fibroblasts. These data indicate that renal TCs protect against renal IRI via an inflammation‐independent pathway and that growth factors play a significant role in this mechanism. Renal TCs may protect TECs in certain microenvironments while interacting with other cells.     

Zinc distribution in injured myocardium

Electron microscopic X-ray microanalysis and atomic absorption spectrophotometry were used to determine changes in zinc concentration after myocardial ischemic injury by coronary ligature in dogs. The zinc concentration increased in the damaged myocardium especially in specific intracellular locations identified by means of the microprobe. It was concluded that the selective zinc augmentation was related to proliferative and biosynthetic reactive processes in the myocardium.     

Emerging concepts in molecular MRI

Molecular magnetic resonance imaging (MRI) offers the potential to image some events at the cellular and subcellular level and many significant advances have recently been witnessed in this field. The introduction of targeted MR contrast agents has enabled the imaging of sparsely expressed biological targets in vivo. Furthermore, high-throughput screens of nanoparticle libraries have identified nanoparticles that act as novel contrast agents and which can be targeted with enhanced diagnostic specificity and range. Another class of magnetic nanoparticles have also been designed to image dynamic events; these act as 'switches' and could be used in vitro, and potentially in vivo, as biosensors. Other specialized MR probes have been developed to image enzyme activity in vivo. Lastly, the use of chemical exchange and off-resonance techniques have been developed, adding another dimension to the broad capabilities of molecular MRI and offering the potential of multispectral imaging. These and other advances in molecular MRI offer great promise for the future and have significant potential for clinical translation.     

Virtual reality of stem cell transplantation to repair injured myocardium

The search for the fountain of youth continues into the 21st century with hopes that embryonic or hematopoietic stem cells (SC) will repair injured tissues in the heart, lungs, pancreas, muscles, nerves, liver, or skin. This commentary focuses on the potential of SC for inducing cardiac regeneration after myocardial injury, the barriers to SC treatment that need to be overcome for ensuring successful cardiac repair, and the experimental approaches that can be applied to the problem.     

In vivo characterization of myocardium muscarinic receptors by positron emission tomography

The feasibility of studying myocardium muscarinic receptors, non invasively, in a “live” being can be demonstrated using positron emission tomography (PET) and a ligand labelled by carbon 11, an externally detectable short lived radionuclide. Criteria necessary for in vitro characterization of muscarinic receptors by a specific ligand were verified in vivo by this method. This demonstration was carried out after injecting in a baboon, high specific activity ¹¹C-MQNB (the methiodide salt of quinuclidinyl benzylate) a muscarinic antagonist drug, and displacing the radioactive ligand by increasing amounts of atropine. Displacement was proportionnal to the dose of atropine and a correlation was observed between displacement and pharmacological activity (increase of heart rate). Stereospecificity of the binding was also demonstrated by using two stereoisomers of benzetimide : dexetimide and levetimide.     

New concepts in pacemaker syndrome

After implantation of a permanent pacemaker, patients may experience severe symptoms of dyspnea, palpitations, malaise, and syncope resulting from pacemaker syndrome. Although pacemaker syndrome is most often ascribed to the loss of atrioventricular (A-V) synchrony, more recent data may also implicate left ventricular dysynchrony caused by right ventricular pacing. Previous studies have not shown reductions in mortality or stroke with rate-modulated dual-chamber (DDDR) pacing as compared to ventricular-based (VVI) pacing. The benefits in A-V sequential pacing with the DDDR mode are likely mitigated by the interventricular (V-V) dysynchrony imposed by the high percentage of ventricular pacing commonly seen in the DDDR mode. Programming DDDR pacemakers to encourage intrinsic A-V conduction and reduce right ventricular pacing will likely decrease heart failure and pacemaker syndrome. Studies are currently ongoing to address these questions.     

New developments in MRI: System characterization,technical advances and radiotherapy applications

A Special Issue of Physica Medica – European Journal of Medical Physics, focused on some important points of contact between the world of magnetic resonance and that of medical physics, was published during 2021. This Editorial describes and comments on the content of this Focus Issue, which contains articles from leading groups invited by the Guest Editors.     

Comparison of kinematics in the healthy and ACL injured knee using MRI

Magnetic Resonance Imaging (MRI) was used to examine the characteristics of abnormal motion in the injured knee by mapping tibiofemoral contact. Eleven healthy subjects and 20 subjects with a unilateral ACL injury performed a leg-press against resistance. MRI scans of both knees at 15 degrees intervals from 0 degrees to 90 degrees of flexion were used to record the tibiofemoral contact pattern. The tibiofemoral contact pattern of the injured knees was more posterior on the tibial plateau than the healthy knees, particularly in the lateral compartment. The tibiofemoral contact pattern of the loaded knees did not differ from the unloaded knees. The difference in the tibiofemoral contact pattern in the ACL injured knee was associated with more severe knee symptoms, irrespective of the passive anterior laxity of the knee.     

Biochemical characterization of exercise-trained porcine myocardium.

The purpose of this study was to determine whether cardiac biochemical adaptations are induced by chronic exercise training (ET) of miniature swine. Female Yucatan miniature swine were trained on a treadmill or were cage confined (C) for 16-22 wk. After training, the ET pigs had increased exercise tolerance, lower heart rates during exercise at submaximal intensities, moderate cardiac hypertrophy, increased coronary blood flow capacity, and increased oxidative capacity of skeletal muscle. Myosin from both the C and ET hearts was 100% of the V3 isozyme, and there were no differences between the myosin adenosine triphosphatase (ATPase) or myofibrillar ATPase activities of C and ET hearts. Also, the sarcoplasmic reticulum Ca(2+)-ATPase activity and Na(+)-Ca2+ exchange activity of sarcolemmal vesicles were the same in cardiac muscle of C and ET hearts. Finally, the glycolytic and oxidative capacity of ET cardiac muscle was not different from control, since phosphofructokinase, citrate synthase, and 3-hydroxyacyl-CoA dehydrogenase activities were the same in cardiac tissue from ET and C pigs. We conclude that endurance exercise training does not provide sufficient stress on the heart of a large mammal to induce changes in any of the three major cardiac biochemical systems of the porcine myocardium: the contractile system, the Ca2+ regulatory systems, or the metabolic system.     

New concepts in fission yeast morphogenesis

The ability to generate spatial form is a fundamental characteristic of all living organisms, which has been much studied by successive generations of developmental biologists. In recent years increasing numbers of cell biologists have turned their attention to the mechanisms by which cells generate their spatial form. These include the mechanisms that position components in different places within the cell, that specify the position of these components, and that generate the overall shape of these components. These problems are entirely analogous to those studied by developmental biologists, although usually at the level of the whole organism, organ or tissue. Because the organization of all cells is basically similar, it is possible that the concepts and the underlying molecular mechanisms of cell morphogenesis may be highly conserved. In this article we consider the generation of spatial form within the fission yeast cell, focusing on emerging new concepts, which may be applicable to the morphogenesis of other cells.     

Endometriosis: New concepts in the pathogenesis

Endometriosis is a gynaecological disease defined by the histological presence of endometrial glands and stroma outside the uterine cavity. Though there are several theories, research scientists remain unsure as to the definitive cause(s) of endometriosis. Considering the relevant health problems caused by endometriosis, all new information on the pathogenesis of this disease, may have important clinical implications. Goal of this article is to summarize the latest advances in the pathogenesis of endometriosis, with particular emphasis on the embryological theory, that has been recently re-proposed. The possible clinical implications of these findings will be discussed.     

New concepts in the law of the sea

Abstract

Current ocean law negotiations reflect conflicts between two old and competing approaches: the view that the coastal state should control activities in any large adjacent ocean area, and the view that most of the ocean should be left open to the free use of all nations. Both approaches are laissez‐faire, leave the distribution of benefits to arbitrary factors, and are based on national exclusivity. In the negotiations this conflict is exhibited in competing claims regarding navigation, mineral resources, fishing, environmental protection, and strategic uses. A possible resolution has emerged in the concept of the whole ocean as a common resource of humankind, according to which no individual state has a right to benefit from the ocean except pursuant to arrangements sanctioned by the community, and rights to benefit are determined not arbitrarily but by membership in the community. The regime now likeliest to be produced by such an approach includes (1) a narrow territorial sea and various navigation guarantees, (2) a wide coastal band coupling coastal state managerial functions with permanent international prerogatives, and (3) purely international manage‐ment of the deep seabed.