beta-Adrenergic stimulation controls the expression of a thioesterase specific for very-long-chain fatty acids in perfused hearts

Arachidonic acid is not freely stored in the cells. A number of different pathways for the mobilization of this compound have been proposed, including a novel mechanism that involves the release of arachidonic acid from arachidonoyl-CoA by a thioesterase with substrate specificity for very-long-chain fatty acids. In rat heart, the acyl-CoA thioesterase activity can be regulated by a mechanism that involves beta-adrenoceptors. In this paper we demonstrate that beta-adrenergic agonists also regulate the acyl-CoA thioesterase mRNA levels. Isoproterenol (10(-7)M)-a concentration known to exert physiological responses-increases in a time-dependent manner the acyl-CoA thioesterase mRNA levels, an effect blocked by a specific beta-adrenoceptor antagonist. In addition, our results show that cAMP is involved in this process. The acyl-CoA thioesterase mRNA levels are also increased by fasting, but not by di(2-ethylhexyl)phthalate, a peroxisome proliferator. These results may suggest the existence of a beta-adrenoceptor-activated regulatory pathway for arachidonic acid release in cardiac tissue.     

Bioinformatic analysis of the link between gene composition and expressivity in Saccharomyces cerevisiae and Schizosaccharomyces pombe

The compositional non-randomness was studied in genes of Saccharomyces cerevisiae and Schizosaccharomyces pombe. In both species, codon usage is well correlated with expressivity (measured as the codon adaptation index). Both species generally display higher nucleotide non-randomness in the group of highly expressed genes than in the lowly expressed genes. The highly expressed genes in both species are furthermore characterized by marked peaks in non-randomness at N=3 upstream of start codons, N=2 downstream of start codons and at N=1 and N=7 downstream of stop codons, indicating that these nucleotides may be key elements in translational regulation. Intragenic variation in codon usage was also observed to be linked to expressivity. It is suggested that the firm link between expressivity and codon usage calls for codon optimization. Based on bioinformatic calculations, examples of proteins are given for which codon optimizations might be relevant.     

Genetic diversity in sexual diploid and apomictic tetraploid populations of Paspalum notatum situated in sympatry or allopatry

Paspalum notatum is a subtropical grass widely distributed in the temperate areas of America. Diploids are sexual while polyploids give rise to clonal seeds through aposporous apomixis. RAPD markers were used to analyze the genetic structure of three natural populations: i) diploids reproducing sexually (R2X); ii) sympatric apomictic tetraploids collected in the vicinity of the diploids (R4X); iii) allopatric apomictic tetraploids growing in isolation (C4X). The apomictic reproduction rate was evaluated by the use of molecular markers in progeny tests, while chromosome-counting allowed the verification of ploidy levels. Data revealed that the R4X group presented a variation considerably higher than that observed for C4X. Jaccards coefficients were used to produce a cluster diagram using the UPGMA method. All but one tetraploid genotypes grouped together and were associated to diploid genotype A21. The possibility of occasional generation of novel tetraploid clones from the interaction between tetraploid and diploid individuals is discussed.     

Lung compliance, plasma electrolyte levels and acid-base balance are affected by scorpion envenomation in anesthetized rats under mechanical ventilation

To determine the effects of Tityus serrulatus scorpion toxin on lung compliance and resistance, ionic equilibrium and acid-base balance over time in anesthetized and mechanically ventilated rats, we measured air flow, tracheal and esophageal pressure. Lung volume was obtained by electronic integration of airflow signal. Arterial blood samples were collected through a catheter at baseline (before) and 5, 15, 30 and 60 min after scorpion toxin injection for arterial blood gases, bicarbonate, and alkali reserve levels as well as for, sodium, potassium, magnesium, glucose, lactate, hematocrit, and osmolality analysis. Injection of the gamma fraction of the T. serrulatus scorpion venom in rats under mechanical ventilatory support leads to a continuous decrease in lung compliance secondary to pulmonary edema, but no change in airway resistance. The changes in arterial blood gases characterizing metabolic acidosis were accompanied by an increase in arterial lactate and glucose values, suggesting a scorpion toxin-induced lactic acidosis, in association with poor tissue perfusion (hypotension and low cardiac output). Moreover, scorpion toxin injection resulted in hyperosmolality, hyperkalemia, hypermagnesemia and an increase in hematocrit. The experiments have shown a clinically relevant animal model to study severe scorpion envenoming and may help to better understand the scorpion envenoming syndrome.     

A possible interaction between CCKergic and GABAergic systems in the rat brain

Cholecystokinin sulfated octapeptide (CCK-8S) was given to rats i.p. at single doses of 10 and 100 nmol/kg, respectively. It produced a modification in GABA levels in several areas of the rat brain. After 30 min of injection, the lower dose (10 nmol/kg) increased GABA levels in striatum by 31% (P<0.05). The higher dose (100 nmol/kg) enhanced GABA levels either in hippocampus by 78% (P<0.05) or in frontal cerebral cortex by 81% (P<0.05) and decreased in olfactory bulbs by 57% (P<0.01). Thus, these results show that systemic injection of CCK-8S, produced regional specific changes on GABA levels in brain, and these effects were dose-dependent. Systemic pretreatment with the CCK(B) receptor antagonist, PD 135,158, 1 mg/kg i.p., on the endogenous levels of GABA in certain regions was also studied. The selective CCK(B) receptor antagonist, PD 135,158, did not have an effect per se on the endogenous levels of GABA but prevents the action induced by the neuropeptide. We suggest that the action of CCK may be mediated via a selective action on the CCK(B) receptor subtypes.     

Changes in the level of tubulin subunits during development of cotton (Gossypium hirsutum) fiber

The levels of tubulin protein in developing cotton ( Gossypium hirsutum L. cv. Stoneville 825) fibers were measured from 8 to 28 days post-anthesis using commercially available monoclonal antibodies against alpha- and beta-tubulin. As the monoclonal antibodies against alpha- and beta-tubulin were prepared from yeast tubulin and chick brain tubulin, respectively, indirect immunofluorescence microscopy was used to establish that the two monoclonal antibodies recognized microtubule structures in cotton fibers. Western blots of electrophoretically separated proteins in crude extracts of cotton roots and fibers showed that single polypeptides with the expected apparent molecular weight for tubulin subunits were recognized by the antisera. An enzyme-linked immunosorbent assay was used to quantify tubulin levels. From 10 to 20 days post-anthesis the level of tubulin protein increases approximately three-fold. After 20 days post-anthesis, the amount of tubulin relative to total fiber protein reaches a plateau or decreases slightly. The rapid rise in tubulin is correlated with the elongation of the fiber and an increase in cellulose synthesis.     

Updating national diagnostic reference levels for interventional cardiology and methodological aspects

The aim of this study is to propose national diagnostic reference levels (DRL) for updating in the field of interventional cardiology and to include technical details to help plan optimization.Medical physics experts and interventional cardiologists from 14 hospitals provided patient dose indicators from coronary angiography and percutaneous coronary interventions. Information about X-ray system dose settings and image quality was also provided.The dose values from 30,024 procedures and 26 interventional laboratories were recorded. The national DRLs proposed for coronary angiography and percutaneous coronary interventions were respectively 39 and 78 Gy·cm² for air kerma area product (P_KA), 530 and 1300 mGy for air kerma at reference point (K_a,r), 6.7 and 15 min of fluoroscopy time and 760 and 1300 cine images. 36% of the KAP meters required correction factors from 10 to 35%. The dose management systems should allow these corrections to be included automatically. The dose per image in cine in reference conditions differed in a factor of 5.5.Including X-ray system dose settings in the methodology provides an insight into the differences between hospitals. The DRLs proposed for Spain in this work were similar to those proposed in the last European survey. The poor correlation between X-ray systems dose settings and patient dose indicators highlights that other factors such as operation protocols and complexity may have more impact in patient dose indicators, which allows a wide margin for optimization. Dose reduction technology together with appropriate training programs will be determinant in the future reduction of patient dose indicators.     

Diagnostic reference levels during fluoroscopically guided interventions using mobile C-arms in operating rooms: A national multicentric survey

PurposeTo establish diagnostic reference levels (DRLs) and achievable levels (ALs) for the most common fluoroscopically guided interventions (FGIs) performed in operating rooms using mobile C-arm equipment.MethodsA national survey was performed in 57 centers in France. Anonymous data from 6817 patients undergoing FGIs were prospectively collected over a period of 7 months. DRLs (third quartile of the distribution) and ALs (median of the distribution) were determined for each type of intervention in terms of kerma area product (KAP) and fluoroscopy time (FT).ResultsDRLs and ALs were proposed for 31 procedure types related to seven surgical specialties: orthopedics (n = 9), urology (n = 3), vascular (n = 6), cardiology (n = 5), neurosurgery (n = 3), gastrointestinal (n = 3), and multi-specialty (n = 2). DRLs in terms of KAP ranged from 0.1 Gy·cm² for hallux valgus to 78 Gy·cm² for abdominal aortic aneurysm endovascular repair. A factor of 155 was obtained between the FTs for a herniated lumbar disk (0.2 min) and an abdominal aortic aneurysm endovascular repair (31 min). The highest variations were obtained within orthopedic procedures in terms of KAP (ratio 122) and within gastrointestinal procedures in terms of FT (ratio 9). Overall, the FGIs associated with the highest radiation exposure (KAP > 10 Gy·cm²) were found in the cardiology, vascular, and gastrointestinal specialties.ConclusionsDRLs and ALs are suggested for a wide range of FGIs performed in operating rooms using a mobile C-arm. We aim at providing a practical optimization tool for medical physicists and surgeons.