Histological evaluation of atrial muscle sleeve of pulmonary veins as relevant to trigger mapping and ablation

2020 ◽  
Vol 42 (11) ◽  
pp. 1271-1277
Author(s):  
Tulika Gupta ◽  
Arpan Randhawa ◽  
Daisy Sahni
Author(s):  
W. K. Jones ◽  
J. Robbins

Two myosin heavy chains (MyHC) are expressed in the mammalian heart and are differentially regulated during development. In the mouse, the α-MyHC is expressed constitutively in the atrium. At birth, the β-MyHC is downregulated and replaced by the α-MyHC, which is the sole cardiac MyHC isoform in the adult heart. We have employed transgenic and gene-targeting methodologies to study the regulation of cardiac MyHC gene expression and the functional and developmental consequences of altered α-MyHC expression in the mouse.We previously characterized an α-MyHC promoter capable of driving tissue-specific and developmentally correct expression of a CAT (chloramphenicol acetyltransferase) marker in the mouse. Tissue surveys detected a small amount of CAT activity in the lung (Fig. 1a). The results of in situ hybridization analyses indicated that the pattern of CAT transcript in the adult heart (Fig. 1b, top panel) is the same as that of α-MyHC (Fig. 1b, lower panel). The α-MyHC gene is expressed in a layer of cardiac muscle (pulmonary myocardium) associated with the pulmonary veins (Fig. 1c). These studies extend our understanding of α-MyHC expression and delimit a third cardiac compartment.


Author(s):  
R.V. Harrison ◽  
R.J. Mount ◽  
P. White ◽  
N. Fukushima

In studies which attempt to define the influence of various factors on recovery of hair cell integrity after acoustic trauma, an experimental and a control ear which initially have equal degrees of damage are required. With in a group of animals receiving an identical level of acoustic trauma there is more symmetry between the ears of each individual, in respect to function, than between animals. Figure 1 illustrates this, left and right cochlear evoked potential (CAP) audiograms are shown for two chinchillas receiving identical trauma. For this reason the contralateral ear is used as control.To compliment such functional evaluations we have devised a scoring system, based on the condition of hair cell stereocilia as revealed by scanning electron microscopy, which permits total stereociliar damage to be expressed numerically. This quantification permits correlation of the degree of structural pathology with functional changes. In this paper wereport experiments to verify the symmetry of stereociliar integrity between two ears, both for normal (non-exposed) animals and chinchillas in which each ear has received identical noise trauma.


2004 ◽  
Vol 74 (1) ◽  
pp. 74-85 ◽  
Author(s):  
Liu ◽  
Russell ◽  
Smith ◽  
Bronson ◽  
Milbury ◽  
...  

Because reactive oxygen species have been implicated as mediators of inflammatory bowel disease (IBD), we evaluated the potential preventive and therapeutic effects of two dietary antioxidants, glutathione (GSH) and coenzyme Q10 (CoQ10) on dextran sulfate sodium (DSS)-induced colitis in mice. Fifty female 8-wk old Swiss-Webster mice were randomly assigned to 4 groups for a pre-treatment 'prevention' study: (1) GSH (1% of diet); (2) CoQ10 (200 mg/kg/d); (3) DSS only (3% of drinking water); (4) control (no treatment). The mice in groups 1 and 2 were fed with GSH or CoQ10 for 21 wks, and the mice in groups 1, 2 and 3 were provided DSS from wk 7 for 4 cycles (1 cycle = 1 wk DSS followed by 2-wk water). Another 50 mice were randomly assigned to 4 groups for a 21-wk 'treatment' study where the mice in groups 1, 2, and 3 were administered DSS for 6 cycles (18 wks) to induce colitis. GSH and CoQ10 were added from wk 7 until the completion of the protocol. Loose stools and hemocult positivity were modestly but significantly reduced with GSH or CoQ10 at several periods during the intervention in both the prevention and treatment studies. In contrast, histological evaluation revealed increases in colonic dysplasia and ulceration with GSH or CoQ10. Thus, in this mouse model, GSH and CoQ10 appear to have a beneficial effect on acute signs of IBD, but may have an adverse impact on the chronic pathophysiology of the disease. Further studies using additional animal models are required to determine whether GSH or CoQ10 provide a favorable or unfavorable benefit:risk ratio in the prevention or treatment of IBD.


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