Effect of anisotropy on ventricular vulnerability to unidirectional block and reentry by single premature stimulation during normal sinus rhythm in rat heart.

Single high-intensity premature stimuli when applied to the ventricles during ventricular drive of an ectopic site, as in Winfree's "pinwheel experiment," usually induce reentry arrhythmias in the normal heart, while single low-intensity stimuli barely do. Yet ventricular arrhythmia vulnerability during normal sinus rhythm remains largely unexplored. With a view to define the role of anisotropy on ventricular vulnerability to unidirectional conduction block and reentry, we revisited the pinwheel experiment with reduced constraints in the in situ rat heart. New features included single premature stimulation during normal sinus rhythm, stimulation and unipolar potential mapping from the same high-resolution epicardial electrode array, and progressive increase in stimulation strength and prematurity from diastolic threshold until arrhythmia induction. Measurements were performed with 1-ms cathodal stimuli at multiple test sites (n = 26) in seven rats. Stimulus-induced virtual electrode polarization during sinus beat recovery phase influenced premature ventricular responses. Specifically, gradual increase in stimulus strength and prematurity progressively induced make, break, and graded-response stimulation mechanisms. Hence unidirectional conduction block occurred as follows: 1) along fiber direction, on right and left ventricular free walls (n = 23), initiating figure-eight reentry (n = 17) and tachycardia (n = 12), and 2) across fiber direction, on lower interventricular septum (n = 3), initiating spiral wave reentry (n = 2) and tachycardia (n = 1). Critical time window (55.1 ± 4.7 ms, 68.2 ± 6.0 ms) and stimulus strength lower limit (4.9 ± 0.6 mA) defined vulnerability to reentry. A novel finding of this study was that ventricular tachycardia evolves and is maintained by episodes of scroll-like wave and focal activation couplets. We also found that single low-intensity premature stimuli can induce repetitive ventricular response (n = 13) characterized by focal activations.NEW & NOTEWORTHY We performed ventricular cathodal point stimulation during sinus rhythm by progressively increasing stimulus strength and prematurity. Virtual electrode polarization and recovery gradient progressively induced make, break, and graded-response stimulation mechanisms. Unidirectional conduction block occurred along or across fiber direction, initiating figure-eight or spiral wave reentry, respectively, and tachycardia sustained by scroll wave and focal activations.

Positive effect of silymarin on cell growth and differentiation in bovine and murine mammary cells.

Silymarin, a naturally acknowledged hepatoprotector used in humans to treat liver diseases has been tested in murine (HC11) and bovine (BME-UV) mammary epithelial cell lines to evaluate a possible direct effect on cell growth and differentiation in mammary gland. Silymarin enhanced cell proliferation (p < 0.05) from 10 to 1000 ng/ml in association with growth factors, (up to 20%) or alone (up to 15%) versus controls. Furthermore, silymarin (100 ng/ml) was able to increase (p < 0.05) beta-casein gene expression alone or in association with prolactin (5 microg/ml). These effects may be related with protein kinase B (AKT) activation induced by silymarin treatment (p < 0.05) and/or by a dose-related inhibitory effect (p < 0.05) on caspase-3 activity related to a protective role in cell apoptosis. These data suggest that silymarin should be considered a candidate to support mammary gland activity during a lactogenetic state.

Leptin concentration in plasma and in milk during the interpartum period in the mare.

The aim of this work is to investigate on plasma profiles of leptin and estradiol 17beta during the interpartum period and leptin concentrations in the milk and in the colostrum during the period from parturition to the successive delivery in mare. Leptin plasma concentration varied from 5.1+/-2.3 ng/ml after the first parturition (week 0) to 3.0+/-0.7 at week 21 (p<0.05), then it increased to maximal level at week 49 (6.9+/-1.0 ng/ml, p<0.05). Leptin concentration in the colostrum and in the milk has been significantly (p<0.05) higher than that in plasma samples at week 1 (milk 8.8+/-2.3 versus plasma 5.2+/-0.6 ng/ml) and between week 12 and 17. This difference may be explained with a local leptin production at mammary level and supports a role of leptin in the mammary gland and/or in foal intestine. Estradiol 17beta increased from week 15 (17.9+/-2.3 pg/ml) up to 487.9+/-67.7 pg/ml at week 43. Plasma estradiol 17beta rise anticipated by 4 weeks plasma leptin increase and it does not seem to be positively correlated to leptin secretion.

Hepatocyte growth factor exerts multiple biological functions on bovine mammary epithelial cells.

The met proto-oncogene product Met is a member of the family of tyrosine kinase growth factor receptors, and hepatocyte growth factor/scatter factor (HGF/SF) has been identified as its only ligand. Bovine Met and HGF/SF have been recently cloned and their expression has been characterized in the mammary gland, but no data regarding the biological effects of this ligand/receptor couple in bovine mammary cells are yet available. We examined the role of HGF/SF and its receptor in a bovine mammary epithelial cell line (BME-UV). Expression of Met at the mRNA level in BME-UV mammary epithelial cells evaluated by real-time PCR was similar to the expression in MDCK cells, a widely used model for Met biology. Met expression in BME-UV at the protein level was confirmed by western blot. The analysis of some signal transductional pathways downstream from the Met receptor revealed that HGF/SF addition to BME-UV cells induced activation of the extracellular signal-regulated kinase 1/2 proliferative pathway and the Akt antiapoptotic pathway. The BME-UV cells treated with HGF responded with increased proliferation, cell scatter, and motility. Met activation by HGF induced degradation of the extracellular matrix and migration through matrigel coated transwells. Moreover, BME-UV cells included in a 3-dimensional matrix of collagen and treated with HGF developed tubular structures, reminiscent of the mammary gland ducts. These data indicate that HGF and Met might be important regulators of mammary gland growth, morphogenesis, and development in the bovine.

Enteric-coating of pulsatile-release HPC capsules prepared by injection molding.

Capsular devices based on hydroxypropyl cellulose (Klucel® LF) intended for pulsatile release were prepared by injection molding (IM). In the present work, the possibility of exploiting such capsules for the development of colonic delivery systems based on a time-dependent approach was evaluated. For this purpose, it was necessary to demonstrate the ability of molded cores to undergo a coating process and that coated systems yield the desired performance (gastric resistance). Although no information was available on the coating of IM substrates, some issues relevant to that of commercially-available capsules are known. Thus, preliminary studies were conducted on molded disks for screening purposes prior to the spray-coating of HPC capsular cores with Eudragit® L 30 D 55. The ability of the polymeric suspension to wet the substrate, spread, start penetrating and initiate hydration/swelling, as well as to provide a gastroresistant barrier was demonstrated. The coating of prototype HPC capsules was carried out successfully, leading to coated systems with good technological properties and able to withstand the acidic medium with no need for sealing at the cap/body joint. Such systems maintained the original pulsatile release performance after dissolution of the enteric film in pH 6.8 fluid. Therefore, they appeared potentially suitable for the development of a colon delivery platform based on a time-dependent approach.

Diagnostic features of body surface potential maps in patients with myocardial ischemia and normal resting 12-lead electrocardiograms.

Body surface maps recorded from 35 ischemic patients with normal resting 12-lead electrocardiograms were compared with those obtained from 36 age- and sex-matched normal subjects. From instantaneous maps of each subject 187 variables were derived relating to the configuration (80 variables) and magnitude (104 variables) of the potential distribution and duration of the electrocardiographic intervals (3 variables). By using stepwise discriminant analysis we selected 3 variables whose linear combination enabled us to correctly allocate 91% of the study population (jacknife procedure; specificity 92%, sensitivity 91%). To substantiate the validity of the results the discriminant function was tested on a new independent population consisting of 27 ischemic patients and 54 normal subjects from another laboratory. A proper allocation was obtained in 86% of the cases (specificity 87%, sensitivity 85%). The large number of correctly classified ischemic patients and the repeatability of the results indicate that the adopted criteria are good markers of ischemic heart disease.

Involvement of serotonin system in bulimia.

Platelet 3H-imipramine binding was investigated in 8 patients affected by bulimia according to DSM III criteria, and in 7 healthy volunteers. The Bmax +/- SD (fmol/mg protein) was 356 +/- 53 in patients, and 1144 +/- 134 in controls. The Kd +/- SD (nM) was 1.35 +/- 0.44 in patients, and 1.90 +/- 0.72 in controls. There was a significant difference (p less than 0.0001) in Bmax values in the two groups, whereas no significant difference was observed in Kd values. This study suggests the possible involvement of the indoleamine system in bulimia.

Body surface potential mapping in ischemic patients with normal resting ECG.

Patients with ischemic heart disease frequently have a normal 12-lead electrocardiogram. We recorded body surface maps from 14 ischemic patients with normal (group A) and 5 with abnormal (group B) resting electrocardiograms. ST-T map data were compared with those of 36 normal subjects. In ischemic patients the following abnormalities were found: an anomalous location and/or trajectory of the potential minimum (lowest potential) on the chest in some; in others the instantaneous values of the time functions: Mxi (highest potential on the chest), delta Vi (highest potential difference) and integral of s/Vi/dS (integral of the absolute value of the potential function extended to the entire chest surface) were lower. In some ischemic patients, both abnormalities were observed. All changes were detectable during the first 200 msec of ST-T. The anomalous potential patterns were similar in group A and B patients, suggesting an ischemic origin of group A abnormalities. By submitting 10 properly selected variables, obtained from body surface maps, to Fisher's discriminant analysis, we succeeded in correctly classifying more than 90% of the cases. The efficacy of the method was validated by using one third of the cases as a test set, with correct allocation in 80.9% of the cases. We conclude that body surface maps at rest can reveal an altered cardiac electrogenesis induced by myocardial ischemia, not apparent in the 12-lead electrocardiogram.

Haematological and physiological responses of Piemontese beef cattle to different housing conditions.

Public concern for animal welfare has progressively grown over the recent years. In this context, stress has a great economical impact on growth of animals and quality of animal products. The development and validation of methods to assess animal stress, particularly at the farm level, are desirable to evaluate animal production systems. Piemontese breed is traditionally tie-stall housed in the fattening period. Hence, the objective of this study was to characterise a profile of physiological and haematological changes of Piemontese beef cattle under different management conditions (tie-stall and loose housing). Our results suggest that the housing system is an important factor in animal welfare. Indeed, the values of the total protein, lysozyme, cortisol, serum and faecal corticosterone concentration and GR-α gene expression indicate that the tie-stall housing is more stressful than the loose system. All the alterations highlighted in this study considered together may be effective biomarkers of stress and disease susceptibility.

Bacterias causantes de otitis media aguda antes y después de la aplicación de la vacuna antineumococica 13-valente / Acute otitis media-causing bacteria before and after the application of the 13-valent pneumococcal conjugate vaccine

Los microorganismos más frecuentemente responsables de la otitis media aguda (OMA) (Streptococcus pneumoniae y Haemophilus influenzae) son los mismos en los países en vías de desarrollo que en los desarrollados. En los países que administraron la vacuna antineumocócica conjugada, los neumococos disminuyeron como causa de OMA, pero con el tiempo comenzaron a resurgir, sobre todo a expensas de cepas pertenecientes a serotipos no incluidos en la vacuna. El objetivo de este trabajo fue documentar el cambio generado en la bacteriología de la OMA a partir de la incorporación en el calendario oficial argentino de la vacuna conjugada antineumocócica 13-valente en el año 2012. Se realizaron dos estudios prospectivos, descriptivos, transversales, uno previo a la incorporación de la vacuna al calendario nacional (mayo 2009-agosto 2010) donde la población estudiada no se encontraba cubierta para S. pneumoniae y otro posterior, donde la mayoría de los pacientes se encontraban inmunizados (enero-diciembre 2016). Se obtuvieron 433 muestras de 324 pacientes en el primer período y 461 de 246 pacientes en el segundo. Se aisló un total de 326 bacterias en el primer período y 388 en el segundo. Los microorganismos respectivamente aislados en ambos períodos fueron S. pneumoniae (39,5-21,1%), H. influenzae (37,4-44,6%), Moraxella catarrhalis (6,1-7,5%), Staphylococcus aureus (8,6-9,8%), Streptococcus pyogenes (3,0-5,9%), Turicella otitidis (1,8-2,1%), Pseudomonas aeruginosa (0,9-4,1%) y otros (2,4-4,9%). Los neumococos pertenecientes a serotipos vacunales sufrieron una disminución significativa, especialmente el 6A, 9V, 14, 18C, 19A, mientras que los serotipos no vacunales aumentaron significativamente, en particular el 15B, el 11A, el 7C, el 16F y el 22F (AU)

Organisms most frequently responsible for acute otitis media (AOM) (Streptococcus pneumoniae and Haemophilus influenzae) are the same in developing countries as in developed ones. In countries that administered the pneumococcal conjugate vaccine, pneumococci decreased as a cause of AOM, but over time began to re-emerge, especially due to strains belonging to serotypes not included in the vaccine. The objective of this work was to document the change generated in the bacteriology of the OMA from the incorporation of the 13-valent pneumococcal conjugate vaccine in 2012 in the official Argentinean calendar. Two prospective, descriptive, cross-sectional studies were carried out prior to the incorporation of the vaccine into the national calendar (May 2009-August 2010), where the population studied was not covered for S. pneumoniae and a subsequent one, where most of the patients were immunized (January 2016-December 2016). We obtained 433 samples from 324 patients in the first period and 461 from 246 patients in the second. A total of 326 bacteria were isolated in the first period and 388 in the second. The microorganisms respectively isolated in both periods were S.pneumoniae (39.5-21.1%), H.influenzae (37.4-44.6%), Moraxella catarrhalis (6.1-7.5%), Staphylococcus aureus (8.6-9.8%), Streptococcus pyogenes (3.0-5.9%), Turicella otitidis (1.8-2.1%), Pseudomonas aeruginosa (0.9-4.1%) and others (2.4-4.9%). Pneumococci belonging to vaccine serotypes suffered a significant decrease, especially 6A, 9V, 14, 18C, 19A, while nonvaccine serotypes increased significantly, particularly 15B, 11A, 7C, 16F, and 22F (AU)

Seasonality of reproduction in wild boar (Sus scrofa) assessed by fecal and plasmatic steroids.

The collection of biological samples through non-invasive techniques represents one way of monitoring in vivo physiological changes associated with reproductive activity. Such techniques are particularly important for the study of animal species in the wild. The goals of this study were 1) to evaluate fecal progestogen (P), estrogen (E), and androgen (A) by means of radioimmunoassays, in male and female wild boars culled in the Piedmont, Italy area; 2) to compare them with plasmatic concentrations and the animals' reproductive status; and 3) to assess variations in reproductive seasonality between two populations of wild boars living in a mountainous vs. a plain habitat in Piedmont. The results demonstrate a positive correlation between fecal and plasmatic steroid concentrations (r=0.46, 0.58, and 0.45 for plasma P(4) and P, E(2) and E, and T and A; P<0.05). Moreover, high fecal levels of both P and E (>170 ng/g and >100 pg/g respectively) were found in 70.6% of pregnant sows and in none of the non-pregnant animals, thus supporting the use of this technique for detecting pregnancy status in wild boar. Similar birth patterns were displayed by the mountain and plain populations, but births peaked significantly only in the mountain population, in the spring (46%, P<0.05, vs. other seasons). A corresponding autumnal peak of plasma testosterone concentrations in males was displayed only by the mountain population (7.4 vs.<2.0 ng/mL in the other seasons, P<0.05). The correlation between fecal and plasmatic steroid concentrations obtained in this study supports the applicability of this non-invasive sampling technique for monitoring reproductive status in wild boar, thus enabling a more informed and correct management of the species.

Comparison between plasma and milk levels of leptin during pregnancy and lactation in cow, a relationship with beta-lactoglobulin.

Leptin gene is expressed in the mammary tissue and the expression of both leptin and its receptor changes significantly during pregnancy and lactation, with high levels during the first half of pregnancy and a decrease at delivery. The aim of this work was to investigate into leptin concentration in plasma and in milk during pregnancy and the first week after parturition in dairy cow and to analyze the correlation between leptin and beta-lactoglobulin (beta-LG) concentrations in plasma and in milk. The trial was conducted on six Holstein dairy cows, reared in the same environmental conditions and evaluated with similar body condition score, during the complete reproductive cycle from insemination to the delivery. Blood from the jugular vein and milk samples were collected at weekly intervals. Plasma leptin concentration showed a lower level (p < 0.05) at the beginning of pregnancy. Milk leptin concentration showed a higher level (p < 0.01) than plasma level from week 23 to week 29 of pregnancy. Plasma beta-LG concentrations were higher (p < 0.01) compared to plasma concentrations during the first part of pregnancy, then milk levels rise and become higher than plasma levels during the last weeks before dry period. A positive correlation (p < 0.01) was observed between leptin and beta-LG both in plasma and in milk profiles.