Repeated regions in mitochondrial genomes: Distribution, origin and evolutionary significance

All complete or nearly complete mitochondrial genomes of Metazoa (2819) have been subject to bioinformatic analysis to investigate the distribution and features of repeated and palindromic sequences. Repeats are ubiquitous, with 29.9% of genomes containing at least one and 1.95% of total genome length being repeated. Repeat boundaries were tested for the presence of secondary structure motifs, consensus sequences or small repeats, features generally reported as associated with duplications. No significant relationship was detected, suggesting the non ubiquitousness of such features. A mechanism related to gene conversion is proposed to explain the origin of small interspersed repeats.     

Anomalous course and branches of human coronary arteries

132 hearts obtained from cadavers were dissected in order to study anomalies in the course and branches of human coronary arteries. Only in 1 heart was a deviation of the circumflex branch of the left coronary artery taking a course inferior to the coronary sulcus observed. The right coronary artery travelled the entire length of the coronary sulcus on the back of the heart and gave both a posterior ventricular and a collateral branch. Circumflex branches of the right and left coronary arteries did not anastomose.     

Visualization of anomalous origin and course of coronary arteries in 748 consecutive symptomatic patients by 64-slice computed tomography angiography

Background

While the order for a clinical transthoracic examination is fairly standardized, there is considerable variability between laboratories and even among physicians in the same laboratory with regard to the order for transesophageal echocardiograms (TEE). A systematic approach is desirable for more efficient use of physician and patient time, avoidance of inadvertent omission of important views, and to facilitate study review.

Methods

We propose a standardized approach to TEE data acquisition in which cardiac structures are systematically identified and characterized at sequential positions and imaging planes to facilitate organized, efficient and comprehensive assessment.

Results

Our approach to TEE study begins in the mid-esophagus with the imaging plane at 0°. Based on the specific indication for the TEE, a cardiac structure (e.g., mitral valve, left atrial appendage, or interatrial septum) is chosen as the primary focal point for a comprehensive, multiplane analysis. This structure is assessed in 20° – 30° increments as the imaging plane is advanced from 0° to 165°. Using the aortic valve as a reference point, pertinent cardiac structures are then assessed as the imaging plane is reduced to 135°, to 90°, to 40 – 60° and then back to 0°. The probe is then advanced into the stomach to obtain transgastric images at 0°, 90°, and 120°. Finally, the thoracic aorta and pulmonary artery are assessed as the probe is withdrawn from the body. Using this method, an organized and comprehensive TEE can be performed in 10 – 15 minutes.

Conclusion

A standardized and systematic TEE approach is described for efficient and comprehensive TEE study.     

Connections between the phrenic arteries and various visceral arteries]

During an angiographic research carried out over more than 1100 cases, some connections between the phrenic arteries and the arteries of the hepatic, superior mesenteric and renal districts were observed. The AA. point out the presence of these connections even of thin calibre, their right prevalence (71%), and their uncertain embryologic origin.     

Post-Tetanic Repetitive Activity in the Cat Soleus Nerve : Its origin, course, and mechanism of generation

Subsequent to conditioning by a high frequency stimulus axons of the cat soleus nerve respond to single stimuli with brief trains of repetitive action potentials. This phenomenon, post-tetanic repetitive activity (PTR), was studied in individual axons and single motor units of an in situ cat soleus nerve-muscle preparation. The occurrence, intensity, and duration of PTR are principally dependent on the frequency and duration of the conditioning tetanus. PTR occurs synchronously in the axon and muscles of single motor units. An analysis of the temporal relationships of the repetitive nerve and muscle potentials showed that PTR is generated in the motor nerve terminal. It is postulated that PTR is produced by a generator potential which is developed in the post-tetanic period between the unmyelinated nerve terminal and the last node of Ranvier.     

Nucleotide supply, not local histone acetylation, sets replication origin usage in transcribed regions

In eukaryotes, only a fraction of replication origins fire at each S phase. Local histone acetylation was proposed to control firing efficiency of origins, but conflicting results were obtained. We report that local histone acetylation does not reflect origin efficiencies along the adenosine monophosphate deaminase 2 locus in mammalian fibroblasts. Reciprocally, modulation of origin efficiency does not affect acetylation. However, treatment with a deacetylase inhibitor changes the initiation pattern. We demonstrate that this treatment alters pyrimidine biosynthesis and decreases fork speed, which recruits latent origins. Our findings reconcile results that seemed inconsistent and reveal an unsuspected effect of deacetylase inhibitors on replication dynamics.     

Active and passive properties of carotid arteries]

A mathematical model of carotid arteries is constructed from the known experimental data. Passive properties of the vascular wall are characterized by an alternating module of elasticity, the active ones by the specific power of muscle contraction. Its maximum value (0,023 n/m-3) is shown to be reached with intravascular pressure 190 mm Hg. The dependence of inner radius on the power of muscle contraction is studied at different values of intravascular pressure. It is shown that theactive properties of carotid arteries are essentially determined by their passive properties and depend on the stretching of the vessel wall.