Gross anatomic relationship between the human left atrial appendage and the left ventricular summit region: implications for catheter ablation of ventricular arrhythmias originating from the left ventricular summit

PURPOSE

The left ventricular summit (LVS) is a source of difficult-to-treat arrhythmias because of anatomical limitations. The aim of this study was to perform detailed research of the left atrial appendage (LAA) anatomy of cadaveric hearts to analyze their complex anatomy and coverage of the LVS.

METHODS AND RESULTS

Eighty human formalin fixed hearts (mean age 44.4 ± 15.5, 27.5% females) were investigated. Each LAA size, type, and its relationship to the LVS were analyzed, as well as possible access sites for mapping/ablating electrode. Four types of LAA were observed over two LVS sites that are either accessible or not. The highest coverage over an inaccessible LVS area was observed in the Broccoli type, followed by the Windsock then the Chicken Wing and finally the Cactus types; over the accessible area of the LVS was observed in the Windsock, then in the Chicken Wing, then in the Cactus, and finally in the Broccoli types. The attainable coverage for electrode access is diminished from 25 to 65% because of the complex pectinate muscles and sharp angles. The highest density of the LAA floor made by pectinate muscles can be found in the Broccoli type (p < 0.005), while the Chicken Wing had the highest number of paper-thin-like pouches.

CONCLUSIONS

The LAA appears to be a promising entry for ablation-qualified patients with the LV summit originate arrhythmias. The complex internal structure of the LAA may complicate ablation procedures. More prominent appendages are promising in more extensive mapping areas over the LVS.

Distinguishing pleiotropy from linked QTL between milk production traits and mastitis resistance in Nordic Holstein cattle

BACKGROUND

Production and health traits are central in cattle breeding. Advances in next-generation sequencing technologies and genotype imputation have increased the resolution of gene mapping based on genome-wide association studies (GWAS). Thus, numerous candidate genes that affect milk yield, milk composition, and mastitis resistance in dairy cattle are reported in the literature. Effect-bearing variants often affect multiple traits. Because the detection of overlapping quantitative trait loci (QTL) regions from single-trait GWAS is too inaccurate and subjective, multi-trait analysis is a better approach to detect pleiotropic effects of variants in candidate genes. However, large sample sizes are required to achieve sufficient power. Multi-trait meta-analysis is one approach to deal with this problem. Thus, we performed two multi-trait meta-analyses, one for three milk production traits (milk yield, protein yield and fat yield), and one for milk yield and mastitis resistance.

RESULTS

For highly correlated traits, the power to detect pleiotropy was increased by multi-trait meta-analysis compared with the subjective assessment of overlapping of single-trait QTL confidence intervals. Pleiotropic effects of lead single nucleotide polymorphisms (SNPs) that were detected from the multi-trait meta-analysis were confirmed by bivariate association analysis. The previously reported pleiotropic effects of variants within the DGAT1 and MGST1 genes on three milk production traits, and pleiotropic effects of variants in GHR on milk yield and fat yield were confirmed. Furthermore, our results suggested that variants in KCTD16, KCNK18 and ENSBTAG00000023629 had pleiotropic effects on milk production traits. For milk yield and mastitis resistance, we identified possible pleiotropic effects of variants in two genes, GC and DGAT1.

CONCLUSIONS

Multi-trait meta-analysis improves our ability to detect pleiotropic interactions between milk production traits and identifies variants with pleiotropic effects on milk production traits and mastitis resistance. In particular, this should contribute to better understand the biological mechanisms that underlie the unfavorable genetic correlation between milk yield and mastitis.

Single nucleotide polymorphisms in the CXCR1 gene and its association with clinical mastitis incidence in Polish Holstein-Friesian cows

The aim of this study was to identify the association between single nucleotide polymorphisms (SNPs) in the bovine chemokine receptor (CXCR1) gene and the resistance or susceptibility of cows to mastitis. The analysis of the CXCR1 polymorphism was carried out using polymerase chain reaction restriction fragment length polymorphism analysis for six SNP mutations (c.+291C>T, c.+365T>C, c.+816C>A, c.+819G>A, +1093C>T, and +1373C>A), of which four were located within the coding region and two in the 3'UTR region of the CXCR1 gene. Genetic material from 146 Polish Holstein-Friesian cows was analyzed after dividing into two groups depending on the incidence of clinical mastitis. Identified polymorphisms were in linkage disequilibrium and formed two linkage groups. Three haplotypes (CCCATA, TTAGCC, CTCGCC), forming six haplotype combinations, were detected. The logistic regression showed a significant association between the CC genotype at c.+365T>C and susceptibility of cows to clinical mastitis (P = 0.047). The frequency of haplotype combination 1/1 (CCCATA/CCCATA) was not significantly higher in cows susceptible to mastitis (P = 0.062). Of the identified SNP mutations, only c.+365T>C is a nonsynonymous mutation that induces a change in the coded protein [GCC (Ala) to GTC (Val) at the 122nd amino acid]. This amino acid change can result in changes in receptor function, which may be a reason for the increased mastitis incidence observed in cows with polymorphism at this site.

New Rapid Method of DNA Isolation from Milk Somatic Cells

Isolation of genomic DNA is one of the basic steps in many different molecular analyses. There are a few reports on methods of DNA isolation from milk, but many of them are time consuming and expensive, and require relatively large volumes of raw milk. In this study a rapid, sensitive, and efficient method of DNA extraction from milk somatic cells of various mammals (cattle, sheep, goats, horses) is presented. It was found that milk is a good source of genomic DNA, and to obtain a sufficient amount and quality of DNA, suitable for molecular analysis such as PCR, 10 mL of raw milk is sufficient. Thanks to this method, stress in animals can be reduced during collection of researched material. Therefore, this method could be widely used in molecular analyses.

Short Communication: New alleles at the BoLA-DQA1 locus in Holstein–Fresian cattle

Kułajaj, D., Pokorska, J., Ormian, M. and Dusza, M. 2015. Short Communication: New alleles at the BoLA-DQA1 locus in Holstein Fresian cattle. Can. J. Anim. Sci. 95: 161–164. The aim of the study was to analyze genetic polymorphism at locus BoLA-DQA1 in Polish Holstein-Friesian cattle, using next generation sequencing technology (Miseq sequencer – Illumina). In the studied cattle population we identified 14 alleles, of which three were determined for the first time (BoLA-DQA1*0106, BoLA-DQA1*3201, BoLA-DQA1*3301). The frequencies of these alleles were respectively: 0.0423, 0.0282, 0.0282. At locus BoLA-DQA1 the highest frequency was found for the BoLA-DQA1*10011 and BoLA-DQA1*0101 alleles and their frequencies were respectively: 0.3592 and 0.2606. The frequencies of other alleles identified in the studied population ranged from 0.0070 to 0.0704. The results obtained in this study indicate that the BoLA-DQA1 locus is highly polymorphic and new alleles are still identifiable.