Electroporation in a Model of Cardiac Defibrillation

INTRODUCTION: It is known that high-strength shock disrupts the lipid matrix of the myocardial cell membrane and forms reversible aqueous pores across the membrane. This process is known as "electroporation." However, it remains unclear whether electroporation contributes to the mechanism of ventricular defibrillation. The aim of this computer simulation study was to examine the possible role of electroporation in the success of defibrillation shock. METHODS AND RESULTS: Using a modified Luo-Rudy-1 model, we simulated two-dimensional myocardial tissue with a homogeneous bidomain nature and unequal anisotropy ratios. Spiral waves were induced by the S1-S2 method. Next, monophasic defibrillation shocks were delivered externally via two line electrodes. For nonelectroporating tissue, termination of ongoing fibrillation succeeded; however, new spiral waves were initiated, even with high-strength shock (24 V/cm). For electroporating tissue, high-strength shock (24 V/cm) was sufficient to extinguish ongoing fibrillation and did not initiate any new spiral waves. Weak shock (16 to 20 V/cm) also extinguished ongoing fibrillation; however, in contrast to the high-strength shock, new spiral waves were initiated. Success in defibrillation depended on the occurrence of electroporation-mediated anodal-break excitation from the physical anode and the virtual anode. Some excitation wavefronts following electrical shock used a deexcited area with recovered excitability as a pass-through point; therefore, electroporation-mediated anodal-break excitation is necessary to block out the pass-through point, resulting in successful defibrillation. CONCLUSION: The electroporation-mediated anodal-break excitation mechanism may play an important role in electrical defibrillation.     

Pathological and laboratory findings in LEC/Otk rats that spontaneously develop hepatic injury

The LEC strain of rats that spontaneously develops hepatic injury has been introduced into specific pathogen-free (SPF) conditions (SPF-LEC/Otk). The present communication describes the clinical and pathological features of the SPF-LEC/Otk rats. The characteristic features of these animals are as follows: (i) Jaundice develops in almost all rats with increase in the P-GPT level; (ii) The animals show episodes of jaundice, a high P-GPT level and liver cell necrosis, but only slight inflammatory cell infiltration; (iii) The liver cells show characteristic microvesicular fatty changes; (iv) The P-GPT level shows increases, first at 18 weeks and then at 25 weeks of age; (v) The rats show immunological disorders, such as deficiency of immunoglobulins, especially IgG1, and of helper T cells; (vi) Infectious agents such as viruses do not seem to be involved, although this possibility cannot be absolutely excluded; (vii) The immunological disorders are not directly associated with the occurrence of liver cell necrosis; and (viii) The pattern of inheritance (autosomal single-recessive trait) of the disease strongly suggests that it is due to a genetic metabolic disorder.     

Desquamative interstitial pneumonia may progress to lung fibrosis as characterized radiologically

Background and objective: In some patients, desquamative interstitial pneumonia may progress to lung fibrosis. The aim of this study was to assess the long‐term radiological follow‐up results in patients with desquamative interstitial pneumonia. Methods: Among 75 patients suspected of having desquamative interstitial pneumonia, 31 who fulfilled the criteria were included in this study. Clinical characteristics at presentation, responses to treatment and long‐term follow‐up were evaluated. Results: The 31 patients were predominantly males (94%), and the mean age was 55 years; 93% (28/30) had a history of smoking. The clinical findings included high serum levels of lactate dehydrogenase and immunoglobulin G. Bronchoalveolar lavage (26 patients, 84% of cases) frequently showed an increased percentage of eosinophils (mean 17%). Computed tomography (CT) or high resolution (HR) CT at presentation showed ground glass opacities and/or consolidation in all patients, with one third of patients also showing thin‐walled cysts within the ground glass opacities. There was no honeycombing on CT or HRCT scans at presentation. Corticosteroid therapy was effective early in the course of the disease; long‐term follow‐up (mean 99 months) of 31 patients showed only one death due to progression of the disease, but long‐term follow‐up of 14 patients (mean 125 months) by HRCT showed the development of new thin‐walled cysts and honeycombing in five and lung cancer in four patients, respectively. Conclusions: In a proportion of patients, desquamative interstitial pneumonia may progress to lung fibrosis with honeycombing on HRCT, despite therapy.     

Intra-His Bundle Block Corresponds with Interruption of the Branching Portion of the His Bundle

We compared His-bundle electrograms with pathological findings of the atrioventricular conduction system in four patients with complete atrioventricular intra-His block with narrow QRS complexes on ECG. Split His electrograms were recorded at the time of electrophysiological study. The patients died from noncardiac causes at 10 days, 1 year, 4 years, and 9 years, respectively, after the pacemaker implantation. Serial sections through the atrioventricular conduction system revealed strictly localized more than 50% reduction of conducting cells replaced by fibrosis at the branching portion of His bundle. The proximal portions of the bundle branches also exhibited decrease of the conducting cells showing a rough positive relation with the patient's age. Therefore, we considered that the H₁ spikes seen on His-bundle electrograms originated from the penetrating portion of His, which was virtually intact in our cases, and that the H₂ spikes originated from the right side of the distal branching portion of His.     

Clinical, Electrophysiological, and Histopathological Observations in Supraventricular Tachycardia

Fifty patients with supraventricular tachycardia (SVT) underwent clinical electrophysiological studies (EPS), endomyocardial biopsies and cardiac catheterizations. EPS revealed AV nodal reentrant tachycardia (AVNRT) in seven patients, AV reentrant tachycardia utilizing concealed AV bypass tracts (AVR-CBT) in nine patients, AV reentrant tachycardia utilizing AV bypass tracts with ventricular preexcitation (manifest WPW) in 13 patients, sinus nodal or intra-atrial reentrant tachycardia (SNRT or IART) in three patients, atrial flutter (AF) in nine patients, automatic atrial tachycardia (AAT) in five patients, and multifocal atrial tachycardia (MAT) in four patients. According to the clinical observations, three patients with AVNRT (43%), six with AVR-CBT (67%), six with manifest WPW (46%), two with SNRT or IART (67%), eight with AF (89%), two with AAT (40%), and two with MAT (50%) showed other accompanying clinical abnormalities. In all patients who were studied histologically, changes in the myocardium were seen; myocarditic changes, postmyocarditic changes and nonspecific abnormalities were present in six (12%), 15 (30%), and nine (18%) respectively. Myocardial changes were observed in four out of seven cases with AVNRT (57%), in six out of nine with AVR-CBT (67%), in five out of 13 with manifest WPW (38%), in two out of three with SNRT or IART (67%), in six out of nine with AF (67%), in all five cases of AAT (100%), and in two out of four with MAT (50%). Nineteen out of 32 without clinical abnormalities except for arrhythmias (59%) had myocardial changes (six had myocarditic changes, ten had postmyocarditic changes, and three had nonspecific abnormalities). On the other hand, nine out of 21 with myocarditic or postmyocarditic changes were accompanied with various arrhythmias other than SVT (two had SSS, five had AV block or rBBB, and two had VT). Elevated LVEDP was present in 36% of the group with normal myocardium and in 53% of the group with myocardial changes. However, the low EF was shown in no patients with normal myocardium but in 21% of the group with myocardial changes. The low CI was also shown in only 9% of the group with normal myocardium but in 28% of the group with myocardial changes. These results suggest that patients with SVT may exhibit several histopathological changes in the myocardium, even in the absence of any clinical organic heart disease.     

Relationship among work–treatment balance,job stress,and work engagement in Japan: a cross-sectional study

There is a drive to support workers in Japan undergoing medical treatment who wish to continue working, known as the work–treatment balance. This support for the work–treatment balance is expected to boost their mental health. This study examines the relationship among the work–treatment balance, job stress, and work engagement. This study was conducted in December 2020 in Japan, with 27,036 participants. We divided the participants into three groups by the receipt state of support for work–treatment balance: control group (do not need support), unsupported group, and supported group. The scores on the parameters of the job content questionnaire and the Utrecht Work Engagement Scale (UWES-3) were compared among groups using a multilevel regression with age-sex or multivariate-adjusted models. In the two models, the job control score of the unsupported group was significantly lower than that of the control group. The two social support scores of the supported group were significantly higher than those of the control group. The scores on the UWES-3 of the unsupported group were significantly lower than those of the control group. The support of work–treatment balance for workers could have a positive impact on their mental health.     

Repeated Treatment Protocols for Melasma and Acquired Dermal Melanocytosis

BACKGROUND AND OBJECTIVE: Melasma and acquired dermal melanocytosis (ADM; acquired bilateral nevus of Ota-like macules) are both seen most commonly symmetrically on the face of women with darker skin and are also known as difficult conditions to treat. METHODS: Our topical bleaching protocol with 0.1 to 0.4% tretinoin gel and 5% hydroquinone was performed repeatedly (1-3 times) for melasma (n=163), and a combination treatment with topical bleaching and Q-switched ruby (QSR) laser was performed repeatedly (1-3 times) for ADM (n=62). RESULTS: There is a significant correlation between clinical results (clearance of pigmentation) and the number of sessions in both melasma (p=.019) and ADM (p<.0001). CONCLUSION: The repeated treatment protocol for melasma and ADM showed successful clinical results compared with conventional ones, and they may be applied to other pigment conditions. It may be better that epidermal and dermal pigmentations are treated separately, especially in dark-skinned people who are more likely to suffer postinflammatory hyperpigmentation after inflammation-inducing therapies.     

Contingent negative variation in children with anorexia nervosa

BACKGROUND: Central catecholamines, particularly dopaminergic and noradrenergic systems, have affected the appetitive behavior in patients with anorexia nervosa (AN). The purpose of this study is to distinguish the characteristics of contingent negative variation (CNV) and postimperative negative variation (PINV), which may reflect the level of catecholamine in children with AN. METHODS: Eight children with AN aged 10 to 15 years and 23 age-matched healthy children were recruited. Contingent negative variation was recorded from the frontal midline (Fz), central midline (Cz) and parietal midline (Pz) referenced to linked earlobes during 30 trials consisting of a warning stimulus and an imperative stimulus with an interstimulus interval of 2 s and an intertrial interval of 10 s. The imperative stimulus of each trial required a button press. RESULTS: Children with AN had a diminished amplitude of the CNV. They had a significantly more attenuated early CNV and late CNV amplitude at Cz than normal children. No significant differences were observed between AN children and normal children in the amplitude of PINV at all three electrode sites. No difference could be found between the two groups in the frequencies of normal and abnormal duration of PINV. CONCLUSION: These findings suggest that early CNV may be diminished by norepinephrine deficiency and late CNV may be attenuated by dopaminergic deficiency in children with AN. Reduced CNV may represent impaired cognitive processes which reflect impaired appetitive behavior in AN children.     

Heterogeneity of Histiocytes in Primary Lung Cancer Stained with Anti-S100 Protein, Lysozyme and OKT 6 Antibodies

The heterogeneity of histiocytes in primary lung cancer wasinvestigated by immunohistochemical methods using anti-Sl0Oprotein and anti-lysozyme anti bodies on paraffin sections andOKT-6 monoclonal antibody on frozen sections. T-zone histiocytes (Langerhans cells and their precursors stainedby anti-SlOO protein and/or OKT-6 monoclonal antibodies) heavilyinfiltrated tumor tissues and regional lymph nodes in casesof moderately or well-differentiated adenocarcinoma, especiallyin areas of papillary growth or bronchiolo-alveolar pattern.These cells were interspersed amongst tumor cells showing dendriticfigures and were occasionally present in squamous cell carcinoma.However. they were seldom found in other histological types,particularly in small cell carcinoma and carcinoid tumor. Thedistribution of these cells was different from that of lysozyme-positivemacrophages. In this connection, T-zone histiocytes were thoughtto have a different immunological function from that of themonocyte-macrophage series against lung cancer. The closelysimilar reactivity of T-zone histiocytes with anti-Sl00 proteinand OKT-6 monoclonal antibodies indicated that these two markerscan be employed for paraffin and frozen sections, respectively. Present address: The Second Department of Surgery, Kyushu UniversitySchool of Medicine, Fukuoka, Japan.     

Conductive Properties of the Reentrant Pathway of Ventricular Tachycardia During Entrainment From Outside and Within the Zone of Slow Conduction

Ventricular tachycardia (VT) was entrained with rapid ventricular pacing outside and within the zone of slow conduction (SCZ), and the conductive properties of the reentrant pathway were compared between the two pacing sites. Underlying heart diseases were old myocardial infarction (n = 2), postoperative tetralogy of Fallot (n = 1) or double outlet of the right ventricle (n = 1), dilated cardiomyopathy (n = 1), and pulmonary regurgitation of unknown cause (n = 1). Rapid pacing was continued for 5–10 seconds, and the time interval from paced stimulus to the entrained electrogram at the exit from SCZ (St-Ex) or to the QRS complex (St-QRS) was measured. Rapid pacing was performed at three or more cycle lengths after a decrement in steps of 10 msec. During rapid pacing outside of SCZ and entrainment of VT, constant fusion and progressive fusion were observed, and St-Ex and St-QRS showed the same response pattern: either a frequency dependent prolongation in 4 of 7 VTs or a constant time interval in the others VTs. When rapid pacing was attempted within SCZ, the response of the time intervals from paced site to the QRS (St-QRS) was the same as those observed during pacing outside SCZ except for one VT. In VT with repaired tetralogy of Fallot, the frequency dependent prolongation was observed during pacing from outside of SCZ but not within SCZ. Diseased myocardium extending widely into the outflow tract of the right ventricle may be responsible for the frequency dependent prolongation of St-Ex. In conclusion, the conductive property of the reentrant pathway might be assessed by observing the response patterns of St-Ex or St-QRS interval during transient entrainment of VT outside of SCZ, but exceptions may exist.