Altered Expression of Zonula occludens-1 Affects Cardiac Na+ Channels and Increases Susceptibility to Ventricular Arrhythmias

Zonula occludens-1 (ZO-1) is an intracellular scaffolding protein that orchestrates the anchoring of membrane proteins to the cytoskeleton in epithelial and specialized tissue including the heart. There is clear evidence to support the central role of intracellular auxiliary proteins in arrhythmogenesis and previous studies have found altered ZO-1 expression associated with atrioventricular conduction abnormalities. Here, using human cardiac tissues, we identified all three isoforms of ZO-1, canonical (Transcript Variant 1, TV1), CRA_e (Transcript Variant 4, TV4), and an additionally expressed (Transcript Variant 3, TV3) in non-failing myocardium. To investigate the role of ZO-1 on ventricular arrhythmogenesis, we generated a haploinsufficient ZO-1 mouse model (ZO-1+/−). ZO-1+/− mice exhibited dysregulated connexin-43 protein expression and localization at the intercalated disc. While ZO-1+/− mice did not display abnormal cardiac function at baseline, adrenergic challenge resulted in rhythm abnormalities, including premature ventricular contractions and bigeminy. At baseline, ventricular myocytes from the ZO-1+/− mice displayed prolonged action potential duration and spontaneous depolarizations, with ZO-1+/− cells displaying frequent unsolicited (non-paced) diastolic depolarizations leading to spontaneous activity with multiple early afterdepolarizations (EADs). Mechanistically, ZO-1 deficient myocytes displayed a reduction in sodium current density (INa) and an increased sensitivity to isoproterenol stimulation. Further, ZO-1 deficient myocytes displayed remodeling in ICa current, likely a compensatory change. Taken together, our data suggest that ZO-1 deficiency results in myocardial substrate susceptible to triggered arrhythmias

Ankyrins and Spectrins in Cardiovascular Biology and Disease

Ankyrins are adaptor proteins critical for the expression and targeting of cardiac membrane proteins, signaling molecules, and cytoskeletal elements. Findings in humans and animal models have highlighted the in vivo roles for ankyrins in normal physiology and in cardiovascular disease, most notably in cardiac arrhythmia. For example, human ANK2 loss-of-function variants are associated with a complex array of electrical and structural phenotypes now termed “ankyrin-B syndrome,” whereas alterations in the ankyrin-G pathway for Nav channel targeting are associated with human Brugada syndrome. Further, both ankyrin-G and -B are now linked with acquired forms of cardiovascular disease including myocardial infarction and atrial fibrillation. Spectrins are ankyrin-associated proteins and recent studies support the critical role of ankyrin-spectrin interactions in normal cardiac physiology as well as regulation of key ion channel and signaling complexes. This review will highlight the roles of ankyrins and spectrins in cardiovascular physiology as well as illustrate the link between the dysfunction in ankyrin- and spectrin-based pathways and disease

Virulotyping and Antibiograms of Pathogenic Escherichia coli Isolated from Calves Suffering from Diarrhea

Escherichia coli is an important cause of diarrhea in calves and has negative economic effects on the livestock industry worldwide due to high mortality and reduced growth rate. The present study was aimed to investigate the prevalence of E. coli in 120 fecal samples from diarrheic mixed-sex neonatal calves, molecular detection of virulence genes, and antimicrobial resistance testing. The high occurrence of E. coli (90/120; 75%) was detected in diarrheic calves. The molecular detection of virulence genes (iron, papc, asta, iuta, omp, hyl and iuc) showed that the high occurrence of astA (78.8%), iucD (66.6%), and papC (64.4%) genes in examined strains, while only 19 strains devoid of virulence genes. Furthermore, antimicrobial susceptibility testing of E. coli isolates showed absolute resistance to ampicillin (100%), followed by streptomycin (95.5%), tetracycline, sulfonamides, gentamycin and chloramphenicol (77.7% each). In the other hand, strains revealed high rates of susceptibility to ciprofloxacin (80%) and enrofloxacin (77.8%).  The multidrug-resistant (MDR) E. coli strains were determined as 77.7% (70/90) and the most identified antimicrobial resistance patterns in 31 strains was C, S, CN, N, TET, AM, SXT. Also, the identified antibiotypes had MAR index values ranged from 0.1 to 0.9. The results of current study indicate the importance of routine monitoring of E. coli isolated from diarrhetic calves to reduce the transmission to humans and animals as well as to select the most appropriate antibiotics. The antibiograms in our study emphasizes the risks associated with the random use of antibiotics.

Virulotyping and Antibiograms of Pathogenic Escherichia coli Isolated from Calves Suffering from Diarrhea

Escherichia coli is an important cause of diarrhea in calves and has negative economic effects on the livestock industry worldwide due to high mortality and reduced growth rate. The present study was aimed to investigate the prevalence of E. coli in 120 fecal samples from diarrheic mixed-sex neonatal calves, molecular detection of virulence genes, and antimicrobial resistance testing. The high occurrence of E. coli (90/120; 75%) was detected in diarrheic calves. The molecular detection of virulence genes (iron, papc, asta, iuta, omp, hyl and iuc) showed that the high occurrence of astA (78.8%), iucD (66.6%), and papC (64.4%) genes in examined strains, while only 19 strains devoid of virulence genes. Furthermore, antimicrobial susceptibility testing of E. coli isolates showed absolute resistance to ampicillin (100%), followed by streptomycin (95.5%), tetracycline, sulfonamides, gentamycin and chloramphenicol (77.7% each). In the other hand, strains revealed high rates of susceptibility to ciprofloxacin (80%) and enrofloxacin (77.8%).  The multidrug-resistant (MDR) E. coli strains were determined as 77.7% (70/90) and the most identified antimicrobial resistance patterns in 31 strains was C, S, CN, N, TET, AM, SXT. Also, the identified antibiotypes had MAR index values ranged from 0.1 to 0.9. The results of current study indicate the importance of routine monitoring of E. coli isolated from diarrhetic calves to reduce the transmission to humans and animals as well as to select the most appropriate antibiotics. The antibiograms in our study emphasizes the risks associated with the random use of antibiotics.

Comprehensive study on in vitro propagation of some imported peach rootstocks: in vitro explant surface sterilization and bud proliferation

Abstract The present study was conducted in the Laboratory of Tissue Culture, Horticulture Department, Faculty of Agriculture, Damietta University, Egypt. The objective of this study was to establish a micropropagation protocol suitable for three imported peach rootstocks: Okinawa (P. persica), Nemared (P. persica × P. davidiana) × P. persica), and Garnem (P. dulcis × P. persica) in vitro. The results showed that soaking the explants in sodium hypochlorite (NaOCl) at 20% for 15 min produced the highest responsiveness (82.81%), survival (96.61%), with the lowest mortality (3.14%) and contamination (0.24%). Explants of the Garnem genotype had the best response (89.12%), survival (90.62%), lowest mortality (0.00%), and highest contamination (9.37%) when compared to the other genotypes. In comparison with axillary buds, the shoot tip displayed the highest responsiveness, survival, and death (100, 87.40, and 12.59%, respectively), as well as the least significant contamination (0.00%). Additionally, the percentages of responsive, survived, dead, and contaminated explants at the various collection dates varied significantly. The 6-benzylaminopurine (BAP) concentrations used (3 to 5.0 mg/L) demonstrated similar behavior in terms of in vitro proliferation, with rates of 3.77 to 6.11, 4.33 to 8.88, and 3.33 to 7.44 shoot numbers per explant for the Okinawa, Nemared, and Garnem peach rootstocks, respectively, indicating that the number of shoot proliferations is genotype-dependent. Additionally, using 5.0 mg/L BAP in combination with 0.2 mg/L IBA significantly increased average shoot proliferation (96.29%), number of shoots per explant (7.48), and average leaf number/explant (16.33) compared to the other treatments. Based on these results, adventitious bud development was enhanced during in vitro multiplication of the Okinawa, Nemared, and Garnem peach rootstocks by the synergistic interaction of indole-butyric acid (IBA) and 6-benzylaminopurine (BAP)