Inhibition of connexin 43 in cardiac muscle during intense physical exercise

Endurance training is accompanied by important adaptations in both cardiovascular and autonomic nervous systems. Previous works have shown that the main component of gap junctions in the ventricular myocardium (connexin 43 (Cx43) can be regulated by adrenergic stimulus. On the other hand, training raises vagal and decreases sympathetic tone, while augmenting myocardial sensitivity to sympathetic stimulation during exercise. We therefore evaluated the regulation of Cx43 expression by sympathetic tone during exercise in trained and sedentary mice. Training induced an increase in the protein level of Cx43 by 45–70% under resting conditions. The expression of Cx43 was inhibited in trained but not in untrained mice in response to a 60 min exercise bout. Normal basal expression was restored after 60 min of resting. Cx43 reached a minimum that was not different from basal expression in untrained mice. In accordance, electrocardiography and action potential analysis did not reveal major electrophysiological implications for the drop in Cx43 abundance in trained‐exercise mice. We prevented Cx43 inhibition using propranolol, and observed increased basal mRNA levels of β‐adrenergic receptors without significant changes in the ratio β₁ to β₂. In conclusion, we showed that Cx43 expression is transiently inhibited by β‐adrenergic stimulus in trained mice during acute exercise.     

Practical and technical considerations in establishing an intraoperative radiation therapy program in the community practice

The Radiation Oncology Center in Sacramento, California, has developed a procedure for establishing an intraoperative radiation therapy facility in a community practice. The logistics pertaining to personnel, equipment, physical measurements, and quality assurance are presented. Particular emphasis is given to the most effective means of acquiring the large quantity of data needed to ensure a program of acceptable quality.     

Natural micropolymorphism in human leukocyte antigens provides a basis for genetic control of antigen recognition

Human leukocyte antigen (HLA) gene polymorphism plays a critical role in protective immunity, disease susceptibility, autoimmunity, and drug hypersensitivity, yet the basis of how HLA polymorphism influences T cell receptor (TCR) recognition is unclear. We examined how a natural micropolymorphism in HLA-B44, an important and large HLA allelic family, affected antigen recognition. T cell–mediated immunity to an Epstein-Barr virus determinant (EENLLDFVRF) is enhanced when HLA-B*4405 was the presenting allotype compared with HLA-B*4402 or HLA-B*4403, each of which differ by just one amino acid. The micropolymorphism in these HLA-B44 allotypes altered the mode of binding and dynamics of the bound viral epitope. The structure of the TCR–HLA-B*4405^EENLLDFVRF complex revealed that peptide flexibility was a critical parameter in enabling preferential engagement with HLA-B*4405 in comparison to HLA-B*4402/03. Accordingly, major histocompatibility complex (MHC) polymorphism can alter the dynamics of the peptide-MHC landscape, resulting in fine-tuning of T cell responses between closely related allotypes.     

A technic for osteotomy of the malar bone

On the basis of the results of osteotomy of the malar in malunion of facial fractures, the authors suggest the use of this operation in the correction of maxillary malformations including faulty development of the cheeks. Two cases are described.     

Midfacial necrosis secondary to cocaine-abuse

Midfacial necrosis due to the abuse of inhaled cocaine is a new entity that is included in the differential diagnosis of the midline destructive diseases such as Wegener's granulomatosis, polymorphic reticulosis, nasal lymphoma, infections and the idiopathic midline destructive disease. We report the case of a forty-year-old male who presented necrosis of the nasosinusal tract and optic neuropathy as complications due to the abuse of inhaled cocaine for more than twenty years and a discussion about the differential diagnosis.     

External Cephalic Version at Term

Summary: The case notes of women with singleton term (37 weeks' gestation and beyond) breech presentation and delivery were retrospectively reviewed. Thirty-two of the 72 women in the study group had attempted external cephalic version at term, with a success rate of 53% (17 women). The Caesarean section rate was significantly lower in the group which had attempted ECV compared to the group which did not.