Evaluation of the Presence and Viability of Mycobacterium bovis in Wild Boar Meat and Meat-Based Preparations

The aim of the present study is to provide information about the ability of Mycobacterium bovis to survive within wild boar (Sus scrofae) meat and meat-based preparations and the duration of this survival, and to consider the preservation of its infectious potential toward humans and animals. Meat samples were artificially contaminated with an M. bovis field strain and then stored at −20 °C, while two sausages batches were contaminated with the same field strain at two different concentrations, 105 CFU/g and 103 CFU/g, before storing them in proper conditions to allow for their ripening. A third sausage batch was contaminated by adding 2 g of wild boar lymph nodal tissue with active tuberculous lesions to the meat mixture. Bacteriological and biomolecular (PCR) methods were used to test the meat and sausage samples every 60 days and every 7–10 days, respectively. M. bovis was detected as still alive and viable on the frozen meat for the last test on the 342nd day, while from the sausage samples, M. bovis was isolated until 23 days after contamination. Our results indicate that M. bovis can stay alive and be viable for 23 days within sausages prepared with contaminated meat from infected wild boars. These products are usually eaten as fresh food after grilling, often cooking at a temperature that does not ensure complete inactivation of the pathogenic microorganisms present, which can pose a risk for humans to develop zoonotic tuberculosis.

Ionic basis of atrioventricular conduction: ion channel expression and sarcolemmal ion currents of the atrioventricular canal of the rainbow trout (Oncorhynchus mykiss) heart

Atrioventricular (AV) nodal tissue synchronizes activities of atria and ventricles of the vertebrate heart and is also a potential site of cardiac arrhythmia, e.g., under acute heat stress. Since ion channel composition and ion currents of the fish AV canal have not been previously studied, we measured major cation currents and transcript expression of ion channels in rainbow trout (Oncorhynchus mykiss) AV tissue. Both ion current densities and expression of ion channel transcripts indicate that the fish AV canal has a characteristic electrophysiological phenotype that differs from those of sinoatrial tissue, atrium and ventricle. Two types of cardiomyocytes were distinguished electrophysiologically in trout AV nodal tissue: the one (transitional cell) is functionally intermediate between working atrial/ventricular myocytes and the other (AV nodal cell) has a less negative resting membrane potential than atrial and ventricular myocytes and is a more similar to the sinoatrial nodal cells in ion channel composition. The AV nodal cells are characterized by a small or non-existent inward rectifier potassium current (IK1), low density of fast sodium current (INa) and relatively high expression of T-type calcium channels (CACNA3.1). Pacemaker channel (HCN4 and HCN2) transcripts were expressed in the AV nodal tissue but If current was not found in enzymatically isolated nodal myocytes. The electrophysiological properties of the rainbow trout nodal cells are appropriate for a slow rate of action potential conduction (small INa) and a moderate propensity for pacemaking activity (absence of IK1).

Abstract MP113: Protein Hyperacetylation Mediates Bradyarrhythmia in Mice With Mitochondrial Disease

Background: Mice with germline mutation of the mitochondrial respiratory complex I subunit Ndufs4 exhibit progressive neurodegenerative phenotypes resembling Leigh syndrome (LS). Cardiomyocyte-specific Ndufs4 -/- mice demonstrate protein hyperacetylation and accelerated heart failure in response to pressure overload. Methods and Results: LS mice developed bradyarrhythmia with heart rate <400 bpm. EKG showed sick sinus syndrome (SSS) and high degree AV block. Supplementation of Nicotinamide Riboside (NR), which increased cellular NAD + , significantly reduced arrhythmia events and restored normal sinus rhythm, as shown by confocal scanning of sinoatrial nodal tissue dissected from LS mouse hearts. Immunoprecipitation and immunohistochemistry using antibody specific for K1479 of Nav 1.5 showed hyperacetylation of LS SA nodal tissue, which was attenuated by NR. HEK293-cells deficient in mitochondrial complex I subunit Ndufs2 had higher DCFDA (ROS) and lower TMRM intensity (mitochondrial membrane potential) compared with Ndufs4 knock-out cells. Ndufs2-knock-out HEK293 cells transfected with wild-type Nav 1.5 showed hyperacetylation of K1479 of Nav 1.5 . Patch clamp showed significantly reduced sodium current (I Na ) in Ndufs2 deficient HEK293 cells. NR prevented the decrease of I Na in Ndufs2 KO cells. HEK293 cells expressing mutant Nav 1.5 constructs mimicking deacetylation (K1479R) had increased I Na compared with HEK293 expressing WT Nav 1.5, suggesting that acetylation status affect Nav1.5 function. Arrythmia was noted in conduction tissue specific HCN4-Ndufs4 -/- mice, suggested a cell autonomous effect leading to arrhythmia. These findings indicate that mitochondrial complex I deficiency lead to hyperacetylation of Nav 1.5 , reduction of I Na , which subsequently cause bradyarrhythmia and this can be reversed by NR. Using echocardiography, we demonstrated significant diastolic dysfunction (decreased E’/A’, prolonged isovolemic relaxation time) in LS mice, which was ameliorated by NR. The calcium transient amplitude and decay rate, an indicator of ryanodine receptor and SERCA2 functions, was significantly decreased by ~15% in LS hearts and this was mitigated by NR, concomitant with reversal of SERCA2 hyperacetylation. Conclusions: Despite normal cardiac structure and systolic function, LS mice showed SSS, high degree AV block and diastolic dysfunction, which is mediated by hyperacetylation of Nav 1.5 and SERCA2, respectively. NR significantly reversed both arrhythmia and diastolic dysfunction. Our study demonstrates novel mechanistic link between mitochondrial complex I deficiency and the function of Nav 1.5 and SERCA2.

Cardiomyocyte Expression of ZO-1 Is Essential for Normal Atrioventricular Conduction but Does Not Alter Ventricular Function

Rationale: ZO-1 (Zonula occludens-1), a plasma membrane-associated scaffolding protein regulates signal transduction, transcription, and cellular communication. Global deletion of ZO-1 in the mouse is lethal by embryonic day 11.5. The function of ZO-1 in cardiac myocytes (CM) is largely unknown. Objective: To determine the function of CM ZO-1 in the intact heart, given its binding to other CM proteins that have been shown instrumental in normal cardiac conduction and function. Methods and Results: We generated ZO-1 CM-specific knockout (KO) mice using α-Myosin Heavy Chain-nuclear Cre (ZO-1cKO) and investigated physiological and electrophysiological function by echocardiography, surface ECG and conscious telemetry, intracardiac electrograms and pacing, and optical mapping studies. ZO-1cKO mice were viable, had normal Mendelian ratios, and had a normal lifespan. Ventricular morphometry and function were not significantly different between the ZO-1cKO versus control (CTL) mice, basally in young or aged mice, or even when hearts were subjected to hemodynamic loading. Atrial mass was increased in ZO-1cKO. Electrophysiological and optical mapping studies indicated high-grade atrioventricular (A-V) block in ZO-1cKO comparing to CTL hearts. While ZO-1-associated proteins such as vinculin, connexin 43, N-cadherin, and α-catenin showed no significant change with the loss of ZO-1, Connexin-45 and Coxsackie-adenovirus (CAR) proteins were reduced in atria of ZO-1cKO. Further, with loss of ZO-1, ZO-2 protein was increased significantly in ventricular CM in a presumed compensatory manner but was still not detected in the AV nodal myocytes. Importantly, the expression of the sodium channel protein NaV1.5 was altered in AV nodal cells of the ZO-1cKO versus CTL. Conclusions: ZO-1 protein has a unique physiological role in cardiac nodal tissue. This is in alignment with its known interaction with CAR and Cx45, and a new function in regulating the expression of NaV1.5 in AV node. Uniquely, ZO-1 is dispensable for function of the working myocardium.

IN VITRO CALLUS INDUCTION IN PHARMACOLOGICALLY SIGNIFICANT HERB: ECLIPTA ALBA

A competent protocol was developed for in vitro plant regeneration and multiplication through callus culture of Eclipta alba. Perfect medium for callus establishment through nodal tissue was observed in 2,4-D supplemented media. The callus formed was creamish yellow in colour, showed a growth period of three to four weeks. A moderate quality callus was obtained with different gradients of BAP supplemented medium. A white to creamy callus with rapid growth was observed in the medium supplemented with NAA. Callus was subjected for multiple shoot induction.

Detection of Mycobacterium avium Subspecies Paratuberculosis from Intestinal and Nodal Tissue of Dogs and Cats

Objective. To determine prevalence of MAP in intestinal and nodal tissue from dogs and cats at necropsy at Kansas State University and to determine if an association existed between presence of MAP and gastrointestinal inflammation, clinical signs, or rural exposure. Procedures. Tissue samples were collected from the duodenum, ileum, and mesenteric and colic nodes of adult dogs (73) and cats (37) undergoing necropsy for various reasons. DNA was extracted and analyzed for insertion sequence 900 using nested PCR. Positive samples were confirmed with DNA sequencing. An online mapping system was used to determine if patients lived in an urban or rural environment based on the home address. Medical records were reviewed for clinical signs and histological findings at necropsy. Results. MAP was identified from 3/73 (4.1%) dogs and 3/37 (8.1%) cats. There was no documented association between presence of MAP and identification of histologic-confirmed gastrointestinal inflammation, gastrointestinal clinical signs, or exposure to a rural environment. Conclusion and Clinical Relevance. MAP-specific DNA can be identified within the intestinal and nodal tissue of dogs and cats that do not have pathological lesions or clinical signs consistent with gastrointestinal disease. The significance of this organism’s presence without associated gastrointestinal pathology is unknown.