The efficacy of general anesthesia during pulmonary vein isolation compared with conscious sedation

Background

Catheter ablation (RFA) is significantly more effective in terms of arrhythmia recurrence rate than antiarrhythmic medication. For the duration of the procedure, the patient needs to remain motionless on the operation table. General anesthesia (GA) is widely used during atrial fibrillation (AF) ablation in all over the world, however RFA of AF is performed under conscious sedation (CS) in the most centers in Japan.

It remains controversial whether cardiac anesthesiologists are best suited to manage anesthesia in the electrophysiology lab.

Objective

The aim of this study was to report the efficacy and safety of GA during AF ablation.

Methods

297 patients (67.3±11.7 years, 208 men, 128 paroxysmal, mean follow up 443 days±306) with AF undergoing RFA in our department from January 2018 to December 2021 were retrospectively analyzed. 113 assigned to the GA group, 184 patients to the CS group.

The primary efficacy end point was radiofrequency time, ablation index, force time integral. The secondary end points defined AF recurrence and the complications.

Result

There was no difference in the baseline characteristics between the two groups. There was no difference between groups in AF recurrence (22.1% vs. 14.1%, P=0.103) and complications.However, Patients in GA had shorter radiofrequency times (66.9±3.7 minute vs 79.0±2.9 minutes P=0.01)Ablation index (376±18.6 vs 371±22.6 P<0.05), Force time integral (136±22.3 vs 111.4±45.3).

Conclusion

General anesthesia is superior to conscious sedation with shorter radiofrequency times and higher than Force time integral, ablation index. Moreover, it is not inferior in regard to arrhythmia recurrence or complication rates of catheter ablation of atrial fibrillation.

Funding Acknowledgement

Type of funding sources: None.

Clinical implication of symptom for long-term outcomes after elective percutaneous coronary intervention

Background

The appropriate treatment for silent myocardial ischemia (SMI) is controversial. The prognosis of asymptomatic patients after percutaneous coronary intervention (PCI) is unknown. Asymptomatic patients might be sicker and have delay of diagnosis when they have coronary events in clinical course. We, thus, hypothesized SMI are associate with the poor outcomes after PCI for stable coronary artery disease (CAD).

Purpose

The present study compared the long-term outcomes of patients with SMI vs. stable angina pectoris (SAP) after elective PCI.

Methods

Our prospective registry database included 923 consecutive patients with CAD who underwent PCI from October 2015 to August 2018. Patients with emergent PCI, acute coronary syndrome at admission, or chronic total occlusion patients were not included. A total 613 patients (71.4±11.2 years, 75.7% male) who underwent elective PCI were studied. The end points included all-cause mortality, non-fatal myocardial infarction, and repeat revascularization.

Results

They were divided into 2 groups according to symptom status: SMI (n=392) and SAP (n=221). SMI patients were predominantly men, and more frequently had diabetes mellitus (197 [50.4%] vs. 91 [41.2%], p=0.028), previous myocardial infarction (44 [11.3%] vs. 8 [3.6%], p=0.001) and heart failure hospitalization.Echocardiography showed SMI groups had reduced ejection fraction (56.9±12.6 vs 63.3±9.1, P<0.001), extended left ventricular internal dimension in diastole (48.5±6.2 vs 47.4±5.8, p=0.048) and left ventricular diameter at end systole (32.8±7.6 vs 30.5±7.5, p=0.001). Mean duration of follow-up was 20.9±10.6 months. The incidence of non-fatal myocardial infarction and repeat revascularization was similar between the 2 groups (10 [2.6%] vs. 5 [2.3%], p=0.82, and 50 [12.8%] vs. 30 [13.6%], p=0.77, respectively). The incidence of all-cause and cardiovascular mortality was more frequent in SMI patients (26 [6.6%] vs. 6 [2.7%], p=0.036, and 9 [3.1%] vs 1 [0.5%], p=0.035, respectively). Kaplan-Meier survival curves indicated that SMI patients had significantly higher all cause-mortality than SAP patients (log-rank, p=0.0184, Hazard ratio 1.24 (1.05–1.47), p=0.013). In multivariable analysis, SMI was an independent predictor of all cause-mortality (Hazard-ratio 5.17, 95% CI 1.35–34.29, p=0.014).

Conclusion

In patients with stable CAD undergoing elective PCI, SMI was associated with an increase in mortality. Optimal care for SMI patients after PCI should be clarified in future studies.

Funding Acknowledgement

Type of funding source: None

Safety and efficacy of a hyperaemic agent, intracoronary nicorandil 4mg, for invasive physiological assessments during fractional flow reserve measurement

Background

Fractional flow reserve (FFR) is one of most reliable index for the determining the functional severity coronary artery stenosis. Adenosine is the most commonly used agent for maximal hyperaemia. However, adenosine can cause chest discomfort, bronchial hyper-reactivity, and atrioventricular block. The aim of this study is to evaluate the safety and efficacy of intracoronary nicorandil as an alternative hyperaemic agent for FFR.

Methods and results

We enrolled consecutive 82 patients (87 lesions) who underwent FFR measurement in our center from Nov. 2018. We compared three groups; intravenous infusion of adenosine (150 μg/kg/min); and adenosine added intracoronary nicorandil 2mg; and intracoronary nicorandil 4mg. Mean FFR value was 0.83±0.09, 0.82±0.09, 0.82±0.08, There was a strong correlation among three groups (R2>0.9). Mean cyclic change in FFR was 0.026±0.023, 0.019±0.010, 0.016±0.014, respectively, cyclic change was smallest in intracoronary nicorandil 4mg group (vs ATP; p<0.001, vs ATP + nicorandil 2mg; p<0.001). By Wilcoxon test, mean FFR value of nicorandil 4mg was significant lower than ATP (p=0.0021), and equal to ATP + nicorandil 2mg (p=0.98).

Conclusions

Intracoronary nicorandil 4mg is a simple, safe, and effective way to induce steady-state hyperaemia for FFR.

Figure 1

Funding Acknowledgement

Type of funding source: None

Association between health risks and frailty in relation to the degree of housing damage among elderly survivors of the great East Japan earthquake

Background

Many survivors of the Great East Japan Earthquake that occurred in 2011 were at risk of deteriorating health, especially elderly people living in disaster-stricken areas. The objectives of this prospective study were: a) to clarify the different lifestyle and psychosocial factors associated with frailty by sex among the non-disabled elderly survivors, and b) to describe the differences in characteristics stratified by the degree of disaster-related housing damage.

Methods

We followed 2261 Japanese survivors aged ≥65 years (45.3% male; mean age, 71.7 years) without disability or frailty who completed a self-administered questionnaire at baseline. All participants completed a baseline questionnaire in 2011 and at least one identical follow-up questionnaire between 2012 and 2015 regarding lifestyle (smoking status, alcohol intake, physical activity, sedentary lifestyle, and dietary intake) and psychosocial factors (self-rated health, standard of living, psychological distress, and social networks). Frailty was defined as a score of ≥5 on the Kihon Checklist, which is used by the Japanese government to certify the need for long-term care insurance. Adjusted odds ratios and 95% confidence intervals with frailty as the dichotomous dependent variable and health factors as the independent variables were calculated using a multilevel model for repeated measures by sex, followed by stratification analyses by the degree of housing damage.

Results

Over the 4-year study period, 510 participants (22.6%) developed frailty. In the post-disaster setting, many of the psychosocial factors remained more prevalent 4 years later among survivors with extensive housing damage. The presence of risk factors regarding the development of frailty differed by the degree of housing damage. Among men, psychological distress, in parallel with a poor social network, was related to frailty among only the participants with extensive housing damage and those living in temporary housing, whereas among women, worsening psychological distress was associated only with no damage and no displaced survivors. Among women with extensive damage and displacement, health outcomes such as overweight and diabetes and poor social networks were strongly related to frailty.

Conclusions

Lifestyle and psychosocial factors associated with the risk of frailty differ by sex and the degree of housing damage.

Electronic supplementary material

The online version of this article (10.1186/s12877-018-0828-x) contains supplementary material, which is available to authorized users.

Prehypertension subtype with elevated C-reactive protein: risk of ischemic stroke in a general Japanese population

BACKGROUND

Prehypertension (PreHT) and low-grade inflammation are both known to be related to the incidence of cardiovascular events. This cohort study investigated whether the high-risk group for future ischemic stroke among PreHT subjects can be predicted by stratification of high-sensitivity C-reactive protein (hsCRP).

METHODS

A total of 22,676 subjects aged 40-80 years from the general population who had no cardiovascular history underwent baseline measurement of serum hsCRP, and were followed for the incidence of ischemic stroke.

RESULTS

During the mean follow-up period of 2.7 years, 143 subjects had a first ischemic stroke. In a Cox multivariable model after adjustment for cardiovascular risk factors, there was no significant difference in hazard ratio (HR) for incidence of ischemic stroke between the normotension (NT) and PreHT subjects (HR = 1.72, 95% confidence interval (CI): 0.93-3.18, vs. NT subjects). In contrast, the HR for incidence of ischemic stroke in PreHT subjects with higher hsCRP levels (≥0.5 mg/l in men, ≥0.4 mg/l in women, more than median levels according to sex) was increased compared to NT subjects with lower hsCRP levels (HR = 2.63, 95% CI: 1.11-6.24). Moreover, the HR for incidence of ischemic stroke in PreHT subjects with lower CRP levels (HR = 0.91, 95% CI: 0.31-2.73) did not differ from that in NT subjects with lower hsCRP levels.

CONCLUSIONS

This study showed that, in a Japanese general population, hsCRP was a marker for relatively short-term risk of ischemic stroke in PreHT subjects.

Uncommon electrocardiographic changes corresponding to symptoms during recurrent pulmonary embolism as documented by computed tomography scans

Electrocardiographic (ECG) findings of pulmonary embolism (PE) include S1Q3T3 pattern, right bundle-branch block, right-axis deviation, and T-wave inversion in medial precordial leads. We report other uncommon ECG changes associated with various symptoms during recurrent PE as documented by computed tomography (CT) scans in a single patients. An 83-year-old woman was admitted with PE secondary to deep venous thrombosis in the left leg. During episodes of chest pain, ECG showed QTc prolongation (480 ms) with new T-wave inversion in leads III, aVF, and V1-V3, and ST-segment depression in leads V5-V6. Despite adequate anticoagulant therapy, recurrent episodes of PE occurred in the hospital. When the patient experienced sudden chest tightness, ECG showed a new S-wave notch in lead V1 and clock-wise rotation with sinus tachycardia. She also experienced transient syncope with hypotension. At this time, ECG showed transient atrioventricular junctional rhythm followed by sinus arrest, and CT scan showed a new massive embolus in the main pulmonary trunk with right ventricular dilatation, as demonstrated by echocardiography. The mechanism responsible for QTc prolongation with ST-T changes, the S-wave notch in lead V1 with clockwise rotation, or atrioventricular junctional rhythm with sinus arrest during PE may be associated with myocardial ischemia, acute right ventricular overload, or vagal reflex, respectively.

On the origin of six-rowed barley with brittle rachis, agriocrithon [Hordeum vulgare ssp. vulgare f. agriocrithon (Aberg) Bowd.], based on a DNA marker closely linked to the vrs1 (six-row gene) locus

The origin of six-rowed cultivated barley has been revealed to be more complex since the discovery of agriocrithon, a six-rowed barley with brittle rachis. The present study investigates whether such six-rowed brittle barley is wild or hybrid in nature, by analyzing genetic diversity at the cMWG699 marker locus, which is closely linked to the vrs1 (six-row gene) locus. DNA sequence analysis for 42 accessions showed only three types in six-rowed brittle barleys; in contrast, nine sequence types were found in ten wild barleys, ssp. spontaneum, in our previous study. Nucleotide diversities for the six-rowed brittle barley were 2.8-4.5 times lower than that for the ssp. spontaneum at this marker locus. The three sequence types found in the six-rowed brittle barley also appeared in the six-rowed cultivated barley. A cross-allelism test confirmed that the six-rowed character of the six-rowed brittle barley was controlled by the vrs1 locus. The nucleotide diversity and genealogy demonstrated that f. agriocrithon does not have the same level of diversity as found in wild barley, ssp. spontaneum. Consequently, f. agriocrithon does not appear to represent genuinely wild populations, but more probably originated from hybridization between ssp. spontaneum and six-rowed cultivated barley.

Comparative high resolution map of the six-rowed spike locus 1 (vrs1) in several populations of barley, Hordeum vulgare L

Multiple alleles at the vrs1 locus control the development and fertility of the lateral spikelets of barley (Hordeum vulgare L.), which is a key character in the study of yield, utilization and domestication. In this study, six linkage maps of the vrs1 locus were constructed, using different mapping populations developed from nine different barley cultivars (H. vulgare subsp. vulgare) or mutant and wild barley (H. vulgare subsp. spontaneum). A total of 8387 chromosomes (gametes) were sampled for analysis based on a hypothesis that orders of marker loci were the same over the different parental lines. The results showed that four markers and the vrs1 locus in all cases were arranged in the same order, which was in a good agreement with the hypothesis. This makes the linkage maps suitable for the positional cloning of the alleles at the vrs1 locus.

A DNA marker closely linked to the vrs1 locus (row-type gene) indicates multiple origins of six-rowed cultivated barley ( Hordeum vulgare L.)

The origin of six-rowed cultivated barley was studied using a DNA marker cMWG699 closely linked to the vrs1 locus. Restriction patterns of the PCR-amplified product of the cMWG699 locus were examined in 280 cultivated ( Hordeum vulgare ssp. vulgare) and 183 wild ( H. vulgare ssp. spontaneum) barleys. Nucleotide sequences of the PCR products were also examined in selected accessions. Six-rowed cultivated barleys were divided into two distinct groups, types I and II. Type I six-rowed cultivated barley was distributed widely while type II six-rowed cultivated barley was found only in the Mediterranean region. The type I sequence was also found in a wild barley accession from Turkmenistan whereas the type II sequence was also found in a two-rowed cultivated barley from North Africa and a wild barley from Morocco. These results suggested that the six-rowed type I and II barleys were derived from two-rowed type I and II barleys, respectively, by independent mutations at the vrs1 locus.

Atypical adenomatous hyperplasia of the lung in autopsy cases

BACKGROUND

Atypical adenomatous hyperplasia (AAH) is a possible precursor lesion of adenocarcinoma of the lung, but very few reports of AAH have focused on the autopsy lung.

METHODS

We intended to clarify the characteristics of AAH in the general population by using 207 autopsy cases, ranging in age from 0 to 90 years old.

RESULTS

A total of 179 eligible cases (86.5%) and 1265 tissue slides (7.0 per case) was examined independently by two pathologists. One hundred seventy-nine autopsy cases consisted of 125 males and 54 females, whose median ages were 38 (range 0-90) and 31 (range 0-81) years old, respectively. AAH was microscopically found in five of 179 autopsy cases (2.8%). The male/female ratio was 5/0 and age distribution was 52-63 years of age (median 57). One of five cases with AAH harbored esophageal carcinoma, but the others had no present or previous malignant neoplasm. One of five lesions was high grade and the others were low grade. All five cases showed positive immunoreactivity for proSP-C, a type II pneumocytes marker, but not for p53, Ki-67 or CEA.

CONCLUSIONS

The incidence of AAH was very low in the general autopsy cases, as compared with the previously reported surgically resected lung and senile autopsy cases, and AAH seems to occur after middle age in general.

Detection of Salmonella enteritidis in shell and liquid eggs using enrichment and plating

Detection methods using various enrichment and plating media and immunoconcentration for Salmonella enteritidis in shell and liquid eggs were evaluated. For liquid egg samples naturally contaminated with S. enteritidis, pre-enrichment in 225 ml of buffered peptone water with cysteine followed by selective enrichment in 10 ml of tetrathionate broth was the superior, resulting in the detection of S. enteritidis in all samples on six of the seven types of selective agar substrate investigated. This enrichment procedure also enabled detection of S. enteritidis in most of artificially inoculated shell egg and pasteurized liquid egg samples.

Regional differences in homicide patterns in five areas of Japan

This article describes regional differences in the homicide patterns which occurred in Sapporo City and the surrounding area, and in Akita, Ibaraki, Chiba and Toyama prefectures in Japan. Information collected from each case of homicide included factors such as age, sex of the victim and assailant, causes of death, disposition of the offender, relationship between assailant and victim, reasons for criminal action, et al. The statistical features of homicidal episodes among the five different regions showed considerable variation, as follows. The mean death rates for homicide (number of victims per 100,000 of population) during the period 1986-1995 were 0.44 (Sapporo), 0.8 (Akita), 0.58 (Toyama), 0.7 (Ibaraki) and 0.75 (Chiba), respectively. Close family relationship between the victim and assailant was observed in the homicidal acts which occurred in Sapporo, Akita and Toyama. Assailant's relationship to victim was commonly extra-familial in Ibaraki and Chiba-neighboring megalopolis Tokyo, where some events of murder by a foreigner occurred. Homicide by female assailant, murder by mentally abnormal killers and homicide-suicide events were closely associated with family members. And these factors contributed to the considerable number of victims in Sapporo, Akita and Toyama. But, this close family relationship of the victim to the assailant did not correspond with the elevation in the number of deaths, and it was rather inversely related to the higher death rates recognized in Ibaraki and Chiba. This comparative study suggested that rapid urbanization considerably affects regional differences in homicide patterns.

Two cases of right ventricular ischemic injury due to massive pulmonary embolism

In general, massive pulmonary embolism induces severe right ventricular overload, but pathological changes in the right ventricle due to pulmonary embolism is rarely seen. In this report, we describe two autopsy cases of massive pulmonary embolism without pre-existing cardiopulmonary disease. Both cases were accompanied by myocarditis-like changes in the right ventricle and infiltration of a number of polymorphonuclear neutrophils and mononuclear cells into the dilated right ventricular wall. Transmural or subendocardial coagulation necrosis was not apparent. Almost all of the mononuclear cells were immunohistochemically revealed to be CD68-positive macrophages. We speculated that these findings resulted from ischemia due to massive pulmonary embolism.

Quantitative determination of marine toxins associated with diarrhetic shellfish poisoning by liquid chromatography coupled with mass spectrometry

Quantitative determination by liquid chromatography (LC) coupled with mass spectrometry (MS) was achieved for the following 10 toxins found in association with diarrhetic shellfish poisoning: okadaic acid (OA), dinophysistoxin-1 (DTX1), 7-O-palmitoylokadaic acid (palOA), 7-O-palmitoyldinophysistoxin-1 (pa1DTX1), pectenotoxin-1 (PTX1), pectenotoxin-2 (PTX2), pectenotoxin-2 seco acid (PTX2SA), pectenotoxin-6 (PTX6), yessotoxin (YTX), and 45-hydroxyyessotoxin (YTXOH). Toxins in 2 g of the adductor muscle or the digestive glands of scallops, Patinopecten yessoensis, were extracted with 18 ml of methanol-water (9:1, v/v), freed of polar contaminants by partition between chloroform and water, and treated by solid-phase extraction on a silica cartridge column. Samples containing YTXOH were purified separately on a buffered reversed-phase column. Chromatographic separation was achieved by the following combinations of columns and mobile phases: a Symmetry C18 column with acetonitrile-0.05% acetic acid (7:3, v/v) for OA, DTX1, PTX6 and PTX2SA; a Develosil ODS column with the same mobile phase for PTX1 and PTX2; a Capcellpak column with methanol-2.5% acetic acid (98:2, v/v) for palOA and palDTX1; and an Inertsil ODS column with methanol-0.2 M ammonium acetate (8:2, v/v) for YTX and YTXOH. Carboxylic acid toxins were selectively monitored on [M-H]- ions, sulfated toxins on [M-Na]-ions, and neutral toxins on [M+NH4]+ ions. Average recoveries of the toxins spiked to tissue homogenates ranged from 70 to 134%. Detection limits in the muscle ranged from 5 to 40 ng/g and those in the digestive glands from 10 to 80 ng/g.

T Wave Alternans for Predicting Adverse Effects of Amiodarone in a Patient With Dilated Cardiomyopathy

An implantable cardioverter defibrillator (ICD) was used in a 62-year-old man with dilated cardiomyopathy (DCM) because of hemodynamically intolerable ventricular tachycardia (VT). Amiodarone was administered after a second episode of ICD discharge. Three weeks later, incessant VT appeared, and DC discharge failed to terminate it. Microvolt T wave alternans (TWA), measured by a spectral method, was observed in this patient with and without amiodarone administration. The onset heart rate with TWA was lower and the alternans voltage was higher with amiodarone than without it. The effects of amiodarone appeared to be related to the exacerbation of VT and an increased defibrillation threshold. TWA might be useful in predicting the proarrhythmic effects of amiodarone in similar cases.

Fatal cardiovascular injuries to the unbelted occupant associated with airbag deployment: two case-reports

We present two forensic autopsy cases of unbelted occupants associated with the airbag deployment in motor vehicle collisions. Both victims suffered from cardiovascular injuries which were the cause of death. Case 1: A 50-year-old man sustained a contusion on the left anterior chest with rib fractures and laceration of the intrapericardial inferior vena cava, the right ventricle, and the right pleuropericardium. Case 2: A 40-year-old man sustained multiple rib fractures, sternal fracture, and the rupture of the right ventricle. Autopsies and vehicle examinations revealed that both victims' chest seemed to strike the steering wheel through the deployed airbag. Therefore, we determined that the source of blunt impact force is the steering wheel through the airbag rather than airbag deployment only. In light of these two cases, we learned that the steering wheel should be considered as the blunt impact force inducing cardiovascular injuries even in cases in which the airbag has been deployed.

Pulmonary neuroendocrine cell distribution in sudden infant death syndrome

The density of pulmonary neuroendocrine cells (PNECs) in 21 sudden infant death syndrome (SIDS) cases, 19 controls, and 25 fetuses was studied morphometrically. Formalin-fixed, paraffin-embedded lung samples were immunostained with antibody against chromogranin A (CGA). The percentage of PNEC-positive airways and the density of PNECs in each airway were calculated in all cases. The density of PNECs was expressed as the number of cells per millimeter of basement membrane. The percentage of PNEC-positive airways reached nearly 100% by term and did not change significantly until 12 months of age in both the SIDS cases and the controls. The density of PNECs also showed a rapid increase in the saccular stage fetus and had its peak of about 4 cells/mm around birth. The density of PNECs, including the standard deviation, was higher in SIDS cases than in controls. The uneven distribution of PNECs may affect respiratory control in SIDS victims.

Quantitative analysis of pulmonary neuroendocrine cell distribution of the fetal small airways using double-labeled immunohistochemistry

Pulmonary neuroendocrine cells (PNECs) are supposed to play an essential role in development of fetal lung and neonatal respiratory adaptation. Some previous studies have suggested the close relation between PNECs and sudden infant death syndrome (SIDS). To investigate how PNECs distribute to the thermal bronchioli of fetal lung may be a clue to clarify this relation. Since it is difficult to distinguish bronchiole from alveolus in fetal lung, we performed double immunostaining with antibody against chromogranin A (CGA) and alpha-smooth muscle actin (SMA) which can make clear distinction between them. In this study, formalin-fixed, paraffin-embedded lung tissues from 18 autopsy cases from 16 to 28 weeks of gestation were assessed. CGA immunopositive cells were counted and the length of basement membranes of terminal bronchioli was measured with computed image analyzer. Density of PNECs was expressed as the number of immunopositive cells per millimeter of basement membrane. Terminal bronchiole stained with SMA was clearly distinguished from alveolus at 16 weeks. With gestational age, CGA immunopositive PNECs were gradually increased in 2 folds by the 25th week. After that, their density wasn't changed significantly until termination. It is suggested that PNECs in terminal bronchiole was playing an important role in morphogenesis of alveolar ducts and alveolar sacks.

Patterns and mechanisms of pedestrian injuries induced by vehicles with flat-front shape

To clarify the difference between flat-front vehicles and bonnet-front vehicles with regard to the patterns and mechanisms of vehicle-induced pedestrian injuries, we investigated 101 cases of pedestrians who were struck by the front of a vehicle. There were 33 flat-front vehicle collision cases and 68 bonnet-front vehicle collision cases. The frequency of chest injuries in flat-front vehicle collisions (30.3%) was significantly higher than that in bonnet-front vehicle collisions (11.8%). Lower leg fractures were more common in bonnet-front vehicle collisions than in flat-front vehicle collisions. Although head injuries were common in both cases, the mechanisms of these injuries differed. The pedestrians who were struck by flat-front vehicles tended to sustain more severe injuries at lower impact speeds. All of these results stem from the difference in the front shape of the two types of vehicle. Pedestrians who are struck by the front of flat-front vehicles receive the impact force to the trunk, particularly the chest, at the initial impact and are thrown out forward after the impact, because the front of these vehicles is perpendicular to the road.

Chlorzoxazone: a probe drug whose metabolism can be used to monitor toluene exposure in rats

In this study we investigated cytochrome P450 (CYP) 2E1 expression using a probe drug, chlorzoxazone (CZX), whose metabolism can be used to monitor toluene exposure in rats. The animals received an i.p. injection of toluene (0.25, 0.5 and 1 ml/kg) once a day for 3 days. The total CYP and CYP2E1 content and the aniline and CZX hydroxylase activity (Vmax and CL(int)) increased depending on the dose of toluene administered. At the highest concentration (128 mM) of diethyldithiocarbamate, a specific inhibitor of CYP2E1, the production of 6-hydroxychlorzoxazone (HCZX) in microsomes from toluene-treated rats was reduced by about 80%. The IC50 values in microsomes from toluene-treated rats were between 3 and 5 microM. The production of HCZX and the activity of aniline hydroxylase in toluene-treated rats were correlated with the amount of rat CYP2E1 protein (r = 0.88 and r = 0.88, respectively). The elimination of CZX by toluene-treated rats was increased and the HCXZ production in the toluene-treated group was greater than that in the olive oil control group. The correlations between intrinsic clearance (CL(int): Vmax/Km) in vitro and total body clearance (CL(tot)) of CZX hydroxylation and the elimination half-life (t1/2) of CZX in vivo in toluene-treated rats were high (r = 0.784, P < 0.001; r = -0.678, P < 0.001, respectively). In addition, the metabolic plasma HCZX/CZX ratio did not require multiple blood sampling and 2 h after CZX administration in vivo there was also a high correlation with CL(int) (Vmax/Km) in vitro (r = -0.729, P < 0.001). In conclusion, these results demonstrate that CZX is a very good probe for monitoring induction in toluene-treated rats.

[Antimicrobial susceptibility testing for Mycobacterium tuberculosis by the bioluminescence assay of mycobacterial ATP using filamentous cell treatment]

The antimicrobial susceptibility testing for Mycobacterium tuberculosis by the bioluminescence assay of adenosine triphosphate(ATP) derived from living mycobacteria was improved introducing filamentous cell treatment(FCT) reported for beta-lactam susceptibility test of Pseudomonas aeruginosa by Hattori. Before ATP extraction, bacterial cells were treated with the FCT reagent for 30 minutes at room temperature. Adenosine phosphate deaminase in the FCT reagent simultaneously digested the extracted ATP and released ATP in a liquid culture of M. tuberculosis H37Rv and the RLU level was decreased markedly. Using this improved ATP method, we determined the ATP contents of M. tuberculosis inoculated into Middle-brook 7H9 broth medium with or without drugs. In ethambutol(EB) susceptibility, the ATP method reported previously, showed false-resistance when judged within 7 days. To eliminate false-resistance in EB susceptibility we applied the modified ATP method with FCT treatment to strains determined EB susceptible by reference methods. Using this modified ATP method, we could judge EB susceptibility of 5 ATCC reference strains within 3 days, and these of 15 clinical isolates of M. tuberculosis within 5 days. And all the results obtained were coincident between the ATP method and the reference methods. The reproducibility of this modified ATP method was evaluated with six ATCC reference strains at the concentrations of 0.1 microgram/ml of isoniazid(INH), 2.0 micrograms/ml of rifampicin(RFP), 2.5 micrograms/ml of EB, 2.0 micrograms/ml of streptomycin(SM), and 5.0 micrograms/ml of kanamycin(KM). The test was repeated six times. Reduction of ATP contents were observed in susceptible strains but not in resistant ones within 3 days of cultivation and susceptibilities to drugs could be determined within 3 days at every time when combined FCT to the ATP method. And highly reproducible results were obtained. It is strongly suggested that this modified method is simple, rapid, highly reproducible and nonradiometric, and could be used for the assessment of drug susceptibility for M. tuberculosis.

Phylogeny in the genus Hordeum based on nucleotide sequences closely linked to the vrs1 locus (row number of spikelets)

The phylogenetic relationship between four basic genomes designated H, I, Xa, and Xu in the genus Hordeum was studied using a nuclear DNA sequence. The sequence, cMWG699, is single copy in the H. vulgare genome, and tightly linked to the vrs1 locus which controls two- and six-rowed spikes. DNA fragments homologous to cMWG699 were amplified from diploid Hordeum species and the nucleotide sequences were determined. A phylogeny based on both base substitutions and an insertion-deletion event showed that the H- and Xa-genome groups are positioned in one monophyletic group indicating that the Xa-genome taxa should be included in the H-genome group. The large H-genome group is highly homogeneous. The I and Xu genomes are distinctly separated from H and Xa, and form sister groups. Another phylogeny pattern based on data excluding the insertion-deletion gave a result that the Xa genome forms a sister group to the H-genome group. The difference between the H and Xa genomes was affected only by a single base insertion-deletion event, thus the H and Xa genomes are likely to be closely related. The I and Xu genomes were again distinctly separated from the H and Xa genomes.

A nucleotide sequence linked to the vrs1 locus for studies of differentiation in cultivated barley (Hordeum vulgare L.)

A PCR-amplified DNA, cMWG699, is linked to the vrs1 (formerly v) locus controlling 2- and 6-rowed spikelets. Restriction analysis of the amplified DNA of 65 varieties from Europe, America, and East Asia revealed 3 alleles, named types K, A and D. Two-rowed varieties were mostly of type K allele, and 6-rowed varieties were mostly of type A allele. The type D allele was found only in three 6-rowed varieties. Sequence comparison of these alleles revealed that the type A allele is more closely related to the type K allele than to the type D allele. The sequence analysis also suggested that the types A and D alleles diverged earlier than when 6-rowed barley arose. On the assumption that 2-rowed barleys were the ancestors of 6-rowed barley, 6-rowed barleys with types A and D alleles probably differentiated from 2-rowed barleys with type A and D alleles, respectively, by independent mutations on the vrs1 locus.

Neurally mediated syncope and arrhythmias: a study of syncopal patients using the head-up tilt test

Understanding the causes of syncope in patients with arrhythmia is important in determining the therapeutic interventions. Neurally mediated syncope (NMS) was evaluated in 55 patients with various arrhythmias. The head-up tilt test with or without isoproterenol infusion induced NMS in 41 (74%) patients. When these patients was categorized into 3 types, depending on the development of syncope, vasodilatation was significant in a majority of patients. In 46% of patients with tachyarrythmias, NMS was accompanied by an increase in extrasystole. It was concluded that the evaluation of vasodilatation is important for the preventive strategy of NMS in patients with arrhythmias and that NMS may induce arrhythmias.

[Antimicrobial susceptibility testing for Mycobacterium tuberculosis by measuring mycobacterial adenosine triphosphate]

The antimicrobial susceptibility test for Mycobacterium tuberculosis H37Rv and 43 clinical isolates was performed using a bioluminescence assay by measuring the content of adenosine triphosphate (ATP) derived from mycobacteria. The drugs tested were isoniazid (INH), rifampicin (RFP), ethambutol (EB), streptomycin (SM), and kanamycin (KM). The ATP contents of M. tuberculosis incubated in the Middle-brook 7H9 broth medium containing antituberculous agents were measured at days of 0, 1, 3, 5, 7 and 10. A reduction of ATP content, indicating growth inhibition, was observed in susceptible strains within 5 to 10 days of incubation. Optimal concentrations to distinguish between susceptible and resistant strains were determined as being INH 0.20, RFP 0.50, EB 5.0, SM 4.0, KM 6.0 g/ml. The agreements of ATP method (evaluated at 10 days) with Vite Spectrum and MIC determinations were 81.4% and 100%, respectively. Susceptibilities to most drugs, except for EB, could be determined within 7 days. This method is simple, rapid, nonradiometric, and can be used for drug susceptibility.

Slow ventricular tachycardia located in the epicardium of the left ventricular base and characterized by effects of adenosine triphosphate, nicorandil and verapamil

A 31-year-old male with slow ventricular tachycardia (VT) developed a nonsustained VT with prolongation of the JT intervals after injection of contrast medium and saline into the marginal vein of the coronary sinus. The earliest activation site of the VT existed in the epicardium of the left ventricular base. Adenosine triphosphate prevented induction of VT and prolongation of JT intervals. Ventricular premature contractions showing the same morphology as the VT were also inhibited by nicorandil and verapamil. The mechanism of the VT was suggested to be abnormal automaticity due to an increase in the Ca++ current into cells after prolongation of the action potential duration induced by hypothermia.

Effects of nicorandil, a potassium channel opener, on idiopathic ventricular tachycardia

OBJECTIVES

We assessed the effects of the adenosine triphosphate (ATP)-sensitive potassium channel opener, nicorandil, on ATP- and verapamil-responsive ventricular tachycardias (VTs).

BACKGROUND

Adenosine- or ATP-sensitive VTs are thought to be due to a nonreentrant mechanism, presumably delayed afterdepolarization. We suggest that this potassium channel opener may suppress ATP- and verapamil-sensitive VTs.

METHOD

The subjects included 13 patients with idiopathic VTs, 7 of whom had sustained VT and 6 of whom had nonsustained VT. We evaluated the effects of ATP, nicorandil and verapamil on VTs.

RESULTS

Sustained VT: Verapamil had preventive effects on seven VTs. Four VTs were terminated by ATP, and of these, nicorandil terminated two and prevented exercise-induced VT in the two others. Three ATP-insensitive VTs, which were determined to be due to a reentry by an electrophysiologic study, were not terminated by nicorandil. Nonsustained VT: All six VTs were inhibited by ATP, and five of these were suppressed by nicorandil. Verapamil inhibited four of the five VTs. QT intervals and the corrected QT intervals were significantly shortened by nicorandil.

CONCLUSIONS

Nicorandil suppresses ATP- and verapamil-responsive VTs. One of the mechanisms of suppression by nicorandil might be related to a reduction of calcium in the myocardium, because it reduces the action potential duration.

Decreasing parasympathetic tone activity and proarrhythmic effect after radiofrequency catheter ablation--differences in ablation site

Holter ECG was used to evaluate changes in heart rate variability (HRV), indicators of the autonomic nervous system, and arrhythmia before and after radiofrequency (RF) catheter ablation in patients with symptomatic supraventricular tachycardia. Ablation targets in 43 patients included the atrioventricular (AV) nodal pathway (AVNRT, n = 17), a right free wall accessory pathway (n = 10), a septal accessory pathway (n = 6), and a left free wall accessory pathway (n = 10). The High frequency component (0.15 - 0.40 Hz) or pNN50 of HRV analysis, indicating parasympathetic activity, significantly decreased immediately after RF ablation in the AVNRT and septal accessory pathway groups, but not in the right or left wall groups. In contrast, in all four groups, ventricular premature contractions (VPCs) significantly increased in most of the patients, and ventricular tachycardia occurred in a few of the patients immediately after RF ablation. There was no serious arrhythmia. These alterations in HRV analysis and arrhythmia returned to the control level after 1 week or more. VPCs after RF ablation did not consistently increase as a result of the reduced parasympathetic tone activity, but at the lesion near the conduction system, the increase in VPCs was inhibited by higher parasympathetic tone activity, because the parasympathetic nerve fibers and receptors were distributed in these lesions.