Catalytic activity of Co-nanocrystal-doped tungsten carbide arising from an internal magnetic field

Pt is an excellent and widely used hydrogen evolution reaction (HER) catalyst. However, it is a rare and expensive metal, and alternative catalysts are being sought to facilitate the hydrogen economy. As tungsten carbide (WC) has a Pt-like occupied density of states, it is expected to exhibit catalytic activity. However, unlike Pt, excellent catalytic activity has not yet been observed for mono WC. One of the intrinsic differences between WC and Pt is in their magnetic properties; WC is non-magnetic, whereas Pt exhibits high magnetic susceptibility. In this study, the WC lattice was doped with ferromagnetic Co nanocrystals to introduce an ordered-spin atomic configuration. The catalytic activity of the Co-doped WC was ∼30% higher than that of Pt nanoparticles for the HER during the hydrolysis of ammonia borane (NH₃BH₃), which is currently attracting attention as a hydrogen fuel source. Measurements of the magnetisation, enthalpy of adsorption, and activation energy indicated that the synergistic effect of the WC matrix promoting hydrolytic cleavage of NH₃BH₃ and the ferromagnetic Co crystals interacting with the nucleus spin of the protons was responsible for the enhanced catalytic activity. This study presents a new catalyst design strategy based on the concept of an internal magnetic field. The WC–Co material presented here is expected to have a wide range of applications as an HER catalyst.

The catalytic activity of the Co-doped WC is 30% higher than that of Pt nanoparticles for the hydrogen evolution reaction arising from an internal magnetic field.

Sex-specific relevance of diabetes to occlusive vascular and other mortality: a collaborative meta-analysis of individual data from 980 793 adults from 68 prospective studies

BACKGROUND

Several studies have shown that diabetes confers a higher relative risk of vascular mortality among women than among men, but whether this increased relative risk in women exists across age groups and within defined levels of other risk factors is uncertain. We aimed to determine whether differences in established risk factors, such as blood pressure, BMI, smoking, and cholesterol, explain the higher relative risks of vascular mortality among women than among men.

METHODS

In our meta-analysis, we obtained individual participant-level data from studies included in the Prospective Studies Collaboration and the Asia Pacific Cohort Studies Collaboration that had obtained baseline information on age, sex, diabetes, total cholesterol, blood pressure, tobacco use, height, and weight. Data on causes of death were obtained from medical death certificates. We used Cox regression models to assess the relevance of diabetes (any type) to occlusive vascular mortality (ischaemic heart disease, ischaemic stroke, or other atherosclerotic deaths) by age, sex, and other major vascular risk factors, and to assess whether the associations of blood pressure, total cholesterol, and body-mass index (BMI) to occlusive vascular mortality are modified by diabetes.

RESULTS

Individual participant-level data were analysed from 980 793 adults. During 9·8 million person-years of follow-up, among participants aged between 35 and 89 years, 19 686 (25·6%) of 76 965 deaths were attributed to occlusive vascular disease. After controlling for major vascular risk factors, diabetes roughly doubled occlusive vascular mortality risk among men (death rate ratio [RR] 2·10, 95% CI 1·97-2·24) and tripled risk among women (3·00, 2·71-3·33; χ2 test for heterogeneity p<0·0001). For both sexes combined, the occlusive vascular death RRs were higher in younger individuals (aged 35-59 years: 2·60, 2·30-2·94) than in older individuals (aged 70-89 years: 2·01, 1·85-2·19; p=0·0001 for trend across age groups), and, across age groups, the death RRs were higher among women than among men. Therefore, women aged 35-59 years had the highest death RR across all age and sex groups (5·55, 4·15-7·44). However, since underlying confounder-adjusted occlusive vascular mortality rates at any age were higher in men than in women, the adjusted absolute excess occlusive vascular mortality associated with diabetes was similar for men and women. At ages 35-59 years, the excess absolute risk was 0·05% (95% CI 0·03-0·07) per year in women compared with 0·08% (0·05-0·10) per year in men; the corresponding excess at ages 70-89 years was 1·08% (0·84-1·32) per year in women and 0·91% (0·77-1·05) per year in men. Total cholesterol, blood pressure, and BMI each showed continuous log-linear associations with occlusive vascular mortality that were similar among individuals with and without diabetes across both sexes.

INTERPRETATION

Independent of other major vascular risk factors, diabetes substantially increased vascular risk in both men and women. Lifestyle changes to reduce smoking and obesity and use of cost-effective drugs that target major vascular risks (eg, statins and antihypertensive drugs) are important in both men and women with diabetes, but might not reduce the relative excess risk of occlusive vascular disease in women with diabetes, which remains unexplained.

FUNDING

UK Medical Research Council, British Heart Foundation, Cancer Research UK, European Union BIOMED programme, and National Institute on Aging (US National Institutes of Health).

"Brush Sign" on susceptibility-weighted MR imaging indicates the severity of moyamoya disease

BACKGROUND AND PURPOSE

SWI is a high spatial resolution MR imaging technique showing magnetic inhomogeneity that could demonstrate increased oxygen extraction in focal cerebral ischemia. The aim of this study was to investigate the characteristics in the signal intensity of DMVs by using SWI and to determine whether this method could indicate the severity of the hemodynamics in MMD by evaluating the correlation between SWI stage and hemodynamics on SPECT.

MATERIALS AND METHODS

Consecutive MMD patients were prospectively analyzed before treatment. Routine MR imaging including SWI was performed, and the number of the conspicuous DMVs draining into the subependymal veins was classified: stage 1, mild (< 5); stage 2, moderate (5-10); and stage 3, severe (> 10). The SWI stage was evaluated in correlation with clinical presentations, and CBF and CVR were quantified by using a SPECT iodine 123 N-isopropyl-p-iodoamphetamine split-dose method.

RESULTS

Patients were 12 males and 21 females (range, 8-66 years), consisting of 4 asymptomatic patients, 13 patients with TIA, 9 patients with infarct, and 7 patients with hemorrhage. There was a significant difference in CVR among clinical presentations, though there was no difference in age, Suzuki stage, or CBF. Conversely, SWI stage was significantly higher in patients with TIA and infarct than asymptomatic patients (P < .01). Higher SWI stage significantly had lower CBF and CVR in the middle cerebral artery area (P < .05).

CONCLUSIONS

SWI stage strongly correlates with ischemic presentations in MMD and also correlates with hemodynamics on SPECT, especially CVR. Increased conspicuity of DMVs, known as "brush sign", could predict the severity of MMD.

[Neuroactive steroid and stress response]

Dehydroepiandrosterone sulfate (DHEAS), a neuroactive steroid, has been demonstrated to bind to sigma 1 receptors, and it has antidepressive effects in the forced swimming test. We used the conditioned fear stress, which is useful for investigating the pathogenesis of mood disorders. DHEAS attenuated the conditioned fear stress response in mice, the effects being antagonized by a sigma 1 receptor antagonist. It is interesting that, the DHEAS contents and number of apoptotic cells in the brain of mice showing conditioned fear stress response were decreased and increased, respectively, compared with those in the nonstressed mice. DHEAS prevented the expression of apoptosis induced by conditioned fear stress. These findings suggest that the imbalance of neuroactive steroids and the expression of apoptosis play an important role in the expression of conditioned fear stress response and that the use of DHEAS is a novel therapeutic approach for at least some mood disorders.

Fat-suppressed T2-weighted MRI of the liver: comparison of respiratory-triggered fast spin-echo, breath-hold single-shot fast spin-echo, and breath-hold fast-recovery fast spin-echo sequences

The purpose of our study was to compare the value of respiratory-triggered fast spin-echo, breath-hold single-shot fast spin-echo, and breath-hold fast-recovery fast spin-echo sequences in detecting hepatic lesions. Fat-suppressed T2-weighted magnetic resonance (MR) images obtained with the three sequences in 36 patients with 138 lesions and nine patients without lesions were prospectively analyzed. Quantitative and qualitative analyses, including receiver operating characteristic (ROC) analyses, were performed. The mean lesion-to-liver contrast-to-noise ratio (CNR) for hepatic lesions was highest with the respiratory-triggered fast spin-echo sequence. On the basis of receiver-operating characteristic analyses, tumor detection rates were higher with the breath-hold fast-recovery fast spin-echo sequence (Az = 0.94) than with the respiratory-triggered fast spin-echo sequence (AZ = 0.80, P < 0.0001) or the single-shot fast spin-echo sequence (Az = 0.77, P < 0.0001). The image quality with the breath-hold fast-recovery fast spin-echo sequence was acceptable in all patients. The breath-hold fast-recovery fast spin-echo sequence provided the highest tumor detection in a short imaging time, although the mean lesion-to-liver CNRs were inferior to those of the respiratory-triggered fast spin-echo and the breath-hold single-shot fast spin-echo sequences.

Changes in myometrial and junctional zone thickness and signal intensity: demonstration with kinematic T2-weighted MR imaging

PURPOSE

To demonstrate uterine contractions by evaluating changes during time in the thickness of the myometrium and junctional zone and in signal intensity of the uterus with T2-weighted fast magnetic resonance (MR) images in a kinematic fashion.

MATERIALS AND METHODS

Sagittal MR imaging was performed with T2-weighted fast spin-echo (FSE) and multiphase-multisection single-shot FSE (SSFSE) in 60 premenopausal patients during free breathing. SSFSE MR images were evaluated with cine display. The pattern of uterine contractions and changes in signal intensities of the uterine structures were evaluated. Thickness of both myometrium and junctional zone, and their signal intensities, were measured during 15 phases of SSFSE and FSE MR imaging.

RESULTS

Slow-massive (mean, 55%), middle-cycle (mean, 80%), and fine (mean, 93%) contractions were observed. Shape of junctional zones dynamically changed during time, showing focal (mean, 58%) and diffuse (mean, 82%) thickening and wavelike motions (mean, 88%). Ratio of thickness of the myometrium to junctional zone with FSE MR imaging was not significantly different from the mean ratio during 15 phases of SSFSE MR imaging, although maximum percentage of change of the ratio during 15 phases was 42.5%-56.8%. The signal intensities of the myometrium (97%) and junctional zone (75%) changed during time.

CONCLUSION

Kinematic T2-weighted SSFSE MR images demonstrate uterine contractions related to dynamic changes in thickness and signal intensities of the myometrium and junctional zone, and these findings might affect the diagnosis of uterine disease.

Functional assessment of pancreatic parenchyma after secretin administration using serial T2-weighted echo-planar magnetic resonance imaging

Signal intensity (SI) changes of pancreatic parenchyma were evaluated after intravenous administration of secretin using T2-weighted single-shot spin-echo echo-planar imaging (EPI) to assess this method as a magnetic resonance (MR) test of pancreatic exocrine function. Nine volunteers were studied with serial single-shot EPI of the pancreas for 15 minutes after the injection of secretin or saline. The normal pattern of pancreatic SI change was demonstrated after intravenous injection of secretin, a single peak at 3-4 minutes in the head, body, and tail, followed by a gradual decrease in SI. Saline injection did not induce a significant SI change. There was no statistical difference in the peak contrast ratios (first mean, 1.21-1.25, vs. second mean, 1.18-1.22) and peak times (first mean, 3.2-3.7 minutes, vs. second mean, 3.1-3.6) in a repeat study. By evaluating the pattern of time-response curves obtained from serial T2-weighted EPI after secretin injection, pancreatic exocrine function may be directly assessed at the level of the head, body, and tail.

Evaluation of pelvic adhesions using multiphase and multislice MR imaging with kinematic display

OBJECTIVE

The purpose of this study was to evaluate whether kinematic multiphase and multislice MR imaging could reveal pelvic adhesions.

SUBJECTS AND METHODS

Before surgery, 52 women with gynecologic disorders underwent half-Fourier acquisition single-shot fast spin-echo imaging with multiphase and multislice acquisitions. Images were displayed in a cine mode, and the motion of each organ against adjacent organs was evaluated by two radiologists who were unaware of the patients' histories or of the findings of their clinical examinations or surgeries. Findings from MR imaging were classified into three types relative to the adjacent organs: type 1, sliding, defined as organs moving 1 cm or more; type 2, fine motion, defined as organs moving less than 1 cm; or type 3, no motion. Type 2 was further subdivided into two groups: type 2-A, independent fine movement, and type 2-B, synchronous fine movement. All MR imaging findings were verified by laparotomy or laparoscopy. Peristalsis at the rectum, colon, and small intestine were also evaluated.

RESULTS

A total of 317 interfaces were evaluated. For findings of type 1 (n = 8 interfaces) and type 2-A (n = 245) on kinematic MR imaging, the negative predictive values for adhesions were 100% and 95.5%, respectively. Findings of type 2-B (n = 52) and type 3 (n = 12) with no adhesions were observed in 40.4% and 66.7%, respectively. When type 1 and type 2-A were regarded as negative findings of adhesions, and type 2-B and type 3 as positive, sensitivity, specificity, and accuracy were 72.5%, 87.4%, and 85.4%, respectively. Peristalsis was observed in 69.2% of patients at the rectum, 86.5% at the colon, and 100% at the small intestine.

CONCLUSION

Multiphase and multislice MR imaging with kinematic display may provide new information about the presence of pelvic adhesions.

T2-weighted MRI of the female pelvis: comparison of breath-hold fast-recovery fast spin-echo and nonbreath-hold fast spin-echo sequences

In 49 patients who had pelvic abnormalities, breath-hold T2-weighted fast-recovery (FR)-fast spin-echo (FSE) (imaging time = 24 sec) and nonbreath-hold FSE MR images (2 min 8 sec) were compared qualitatively (on a four-point scale) and quantitatively (using signal-to-noise ratios (SNRs) and contrast ratios (/SIs of the lesions-SIs of the myometrium/SIs of the myometrium)). Motion artifacts were reduced on breath-hold FR-FSE (3.8:3.2 = breath-hold FSE:nonbreath-hold FSE, P < 0.01) and image quality was comparable (3.8:3.7, NS). In all patients, pathology (leiomyoma [N = 26], adenomyosis [N = 10], endometrial carcinoma [N = 8], and ovarian cystic lesions [N = 21]) was recognized with comparable lesion conspicuity (3.8:3.7, NS) and better delineation of the structures (3.9:3.6, P < 0.05) on the FR-FSE images. There was no significant difference in contrast ratios, although SNRs (e.g., myometrium 18.3:25.8, P < 0.01) were better and the uterine zonal anatomy was recognized better on the nonbreath-hold FSE (3.4:3.7, P < 0.05). These differences did not affect the diagnosis. Breath-hold FR-FSE provides the benefits of motionless imaging and a short examination time, although lower SNRs were noted. J. Magn. Reson. Imaging 2001;13:930-937.

Assessment of gadolinium-enhanced time-resolved three-dimensional MR angiography for evaluating renal artery stenosis

OBJECTIVE

The purpose of this study was to assess the image quality of gadolinium-enhanced time-resolved three-dimensional (3D) MR angiography and to evaluate its accuracy in revealing renal artery stenosis.

SUBJECTS AND METHODS

Thirty-nine patients underwent MR angiography using an ultrafast 3D Fourier transform spoiled gradient-recalled acquisition in the steady state (TR/TE range, 2.6/0.7--0.8). Five seconds after administration of 15--20 mL gadodiamide hydrate, four or five consecutive data sets with imaging times of 7.0--7.6 sec were acquired during a single breath-hold. A timing examination was not performed. Image quality was assessed using quantitative analysis (signal-to-noise, contrast-to-noise, and venous-to-arterial enhancement ratios) and qualitative analysis (presence of venous overlap, presence of artifacts, and degree of renal arterial enhancement). MR angiography depiction of the renal artery stenosis was evaluated using conventional angiography as the standard of reference.

RESULTS

On the best arterial phase, average aortic signal-to-noise ratio (+/-SD) was 74.5 +/- 24.4, aorta-to--inferior vena cava contrast-to-noise ratio was 70.8 +/- 23.4, and inferior vena cava--to-aorta venous-to-arterial enhancement ratio was 0.03 +/- 0.04. No venous overlap was seen in 38 of 39 patients. Substantial enhancement of renal arteries was seen in all patients without any noticeable artifacts. MR angiography correctly depicted the degree of stenosis in 44 of 47 normal arteries, 13 of 16 mildly stenotic arteries, five of five moderately stenotic arteries, three of four severely stenotic arteries, and one of one occluded artery. Sensitivity and specificity for revealing greater than 50% stenosis was 100%.

CONCLUSION

Time-resolved 3D MR angiography can provide high-quality arteriograms. Its performance in revealing renal artery stenosis is comparable with that of conventional angiography.

Hepatitis C virus NS5B RNA replicase specifically binds ribosomes

Hepatitis C virus (HCV) non-structural protein 5B (NS5B) is an RNA replicase. We expressed full-length NS5B (591 amino acid residues) in Escherichia coli as a fusion protein with maltose binding protein (MBP-NS5B). MBP-NS5B was recovered in the soluble fraction after centrifugation at 40,000 x g and affinity-purified with amylose resin. The purified MBP-NS5B had a high-level of poly (A), oligo (U)-dependent UMP incorporation with a Km of 2 microM for UTP. Surprisingly, the enzymatically active MBP-NS5B was sedimented by ultracentrifugation at 160,000 x g. The pellet contained 16S and 23S ribosomal RNAs, suggesting that ribosomes were associated with MBP-NS5B. Ribosomes and MBP-NS5B were subsequently co-purified on amylose resin. Deletion study revealed that either the N-terminal (amino acid residues 1-107) or the C-terminal (amino acid residues 498-591) region of NS5B were sufficient for this association with ribosomes. We further found that NS5B also bound with human ribosomes. Our results implicate a novel mechanism of coupling between replication and translation of the viral genome in the life cycle of HCV.

Gadolinium-enhanced MR angiography in the evaluation of congenital cardiovascular disease pre- and postoperative states in infants and children

The purpose of this study was to evaluate the utility of dynamic contrast magnetic resonance (MR) angiography under sedation for assessing congenital cardiovascular disease in infants and small children before and after cardiac surgery. In 38 patients with cardiovascular abnormalities, thoracic vasculatures were evaluated in either the preoperative (group 1; 23 patients, median age 9 months old) or the postoperative (group 2; 15 patients median age 1. 3 years old) state using gadolinium-enhanced dynamic MR angiography. Acquired data were processed with a multiprojection volume reconstruction. Image quality (grades 1-5, undiagnostic to excellent), presence or absence of the extracardiac vasculature, its pathology (group 1), and the patency of the postsurgical shunt or reconstructed vasculature (group 2) were evaluated. All images were of diagnostic image quality (mean grade 4.4-3.2). Recognition of the thoracic vasculature was correctly made in all cases (38/38, 100%). In group 1, anomalies and pathologic changes were correctly identified in 22 of 23 cases (95.7%). In one patient with dextrocardia and the cardiac type of total anomalous pulmonary venous return, the abnormality was not recognized. In group 2, the patency of the shunt flow after Glenn (n = 6), modified Fontan (n = 4), Rastelli (n = 1), and Blalock-Taussig (n = 3) operations was well demonstrated in each case. The reconstructed pulmonary artery (n = 1), veins (n = 2), and aorta (n = 1) were correctly visualized. In one case, stenosis of the reconstructed left pulmonary vein was missed by MR angiography. In 14 of 15 cases in group 2 (93.3%), MR angiography correctly gave information on the operated areas. In conclusion, dynamic contrast MR angiography under sedation is useful for evaluation of the thoracic vasculature of infants and small children in the pre- and postoperative states. J. Magn. Reson. Imaging 2000;12:1034-1042.

A reliable internally controlled RT-nested PCR method for the detection of hepatitis C virus RNA

We have developed a reliable internally controlled RT-nested PCR method for the detection of hepatitis C virus (HCV) RNA using in vitro synthesized Renilla luciferase (Rluc) RNA as an internal control. Using this method, the 5'-noncoding region of HCV RNA (144 nucleotides) and Rluc RNA (276 nucleotides) were efficiently amplified in a single tube, and the sensitivity and specificity of this method were comparable to standard RT-nested PCR. This method was successfully performed on RNA specimens obtained from in vitro HCV-infected human hepatocyte PH5CH8 cells, which support HCV replication. In addition, we demonstrated that this method was useful for the evaluation of antiviral reagents by confirming the anti-HCV activity of bovine lactoferrin, which we previously found to be a new inhibitor of HCV infection. Therefore, this method may be useful for the studies of not only HCV but also of other viruses.

Gadolinium-enhanced MR angiography in the evaluation of congenital cardiovascular disease pre- and postoperative states in infants and children

The purpose of this study was to evaluate the utility of dynamic contrast magnetic resonance (MR) angiography under sedation for assessing congenital cardiovascular disease in infants and small children before and after cardiac surgery. In 38 patients with cardiovascular abnormalities, thoracic vasculatures were evaluated in either the preoperative (group 1; 23 patients, median age 9 months old) or the postoperative (group 2; 15 patients median age 1. 3 years old) state using gadolinium-enhanced dynamic MR angiography. Acquired data were processed with a multiprojection volume reconstruction. Image quality (grades 1-5, undiagnostic to excellent), presence or absence of the extracardiac vasculature, its pathology (group 1), and the patency of the postsurgical shunt or reconstructed vasculature (group 2) were evaluated. All images were of diagnostic image quality (mean grade 4.4-3.2). Recognition of the thoracic vasculature was correctly made in all cases (38/38, 100%). In group 1, anomalies and pathologic changes were correctly identified in 22 of 23 cases (95.7%). In one patient with dextrocardia and the cardiac type of total anomalous pulmonary venous return, the abnormality was not recognized. In group 2, the patency of the shunt flow after Glenn (n = 6), modified Fontan (n = 4), Rastelli (n = 1), and Blalock-Taussig (n = 3) operations was well demonstrated in each case. The reconstructed pulmonary artery (n = 1), veins (n = 2), and aorta (n = 1) were correctly visualized. In one case, stenosis of the reconstructed left pulmonary vein was missed by MR angiography. In 14 of 15 cases in group 2 (93.3%), MR angiography correctly gave information on the operated areas. In conclusion, dynamic contrast MR angiography under sedation is useful for evaluation of the thoracic vasculature of infants and small children in the pre- and postoperative states. J. Magn. Reson. Imaging 2000;12:1034-1042.

Activation of the interferon-inducible 2'-5'-oligoadenylate synthetase gene by hepatitis C virus core protein

The effects of hepatitis C virus (HCV) proteins on several signal transduction pathways in human nonneoplastic hepatocyte PH5CH8 cells were investigated using expression vectors encoding HCV proteins derived from HCV-infected human nonneoplastic cultured T-lymphocyte and hepatocyte cells (MT-2C and PH5CH7), which could support HCV replication. The amino acid sequences of HCV proteins obtained from HCV-infected human cells were identical or very close to the consensus sequences of the proteins derived from the original inoculum used for HCV infection. During the course of the study, we found that HCV core protein specifically activated the 40/46-kDa 2'-5'-oligoadenylate synthetase (2'-5'-OAS) gene promoter in a dose-dependent manner in different human hepatocyte cell lines (PH5CH8, HepG2, and PLC/PRF/5). We also found that the activation by core protein was further enhanced in the cells treated with alpha interferon. The expression of E1 or E2 envelope protein or nonstructural NS5A protein did not activate the 2'-5'-OAS gene promoter. We demonstrated that the activation by core protein in the hepatocyte cells was suppressed by antisense RNA complementary to core-encoding RNA. Deletion mutant analysis of core protein and deletion analysis of the 2'-5'-OAS gene promoter have been performed. Finally, we demonstrated that the activation of the 2'-5'-OAS gene occurred at the transcriptional level and furthermore demonstrated that the endogenous 2'-5'-OAS gene was also activated by core protein. This is the first report to show that a viral protein activated the 2'-5'-OAS gene.

Dynamic MR dacryocystography: a new method for evaluating nasolacrimal duct obstructions

OBJECTIVE

The purpose of this study was to evaluate the clinical performance of newly implemented dynamic MR dacryocystography.

CONCLUSION

Dynamic MR dacryocystography, which requires neither ionizing radiation nor chemical contrast media with high viscosity, may be a useful tool for depicting nasolacrimal obstructions.

Structure-specific effects of thyroxine analogs on human liver 3 alpha-hydroxysteroid dehydrogenase

The NADP(H)-linked oxidoreductase activity of a major isozyme of human liver 3 alpha-hydroxysteroid dehydrogenase was activated 5-, 4-, and 2-fold by D-thyroxine (T(4)), L-T(4) and DL-3,3', 5'-triiodothyronine (reverse T(3)), respectively. Kinetic analysis of the activation indicated that D-T(4), L-T(4), and reverse T(3) are non-essential activators, showing binding constants of 1.5, 1.1, and 3.6 microM, respectively. Comparison of the effects of the T(4) analogs on the activities of the mutant enzymes suggests that the binding site is composed of at least Lys-270, Arg-276, and the C-terminal loop of the enzyme. L-T(3), DL-thyronine, and D-tyrosine had no effect on the enzyme, but 3,5,3',5'-tetra- and 3,5, 3'-tri-iodo thyropropionic acids were potent competitive inhibitors with K(i) values of 42 and 60 nM, respectively, with respect to the substrate. The inhibition constant was lowered upon the activation of the enzyme by D-T(4), and the inhibition by the deamino derivatives of T(4) and T(3) disappeared upon modification of the C-terminal loop of the enzyme, but not upon replacement of Lys-270 or Arg-276 with Met. These results indicate that, depending on their structures, the T(4) analogs bind differently to two distinct sites at the active center of the enzyme to produce stimulatory and inhibitory effects.

MRA of intracranial aneurysm models: a comparison of contrast-enhanced three-dimensional MRA with time-of-flight MRA

PURPOSE

The purpose of our study was to compare contrast-enhanced 3D MR angiography (MRA) using ultrafast spoiled gradient-recalled acquisition in the steady state (SPGR) with 2D and 3D time-of-flight (TOF) MRA for visualization of intracranial lateral saccular aneurysm models.

METHOD

We used lateral saccular aneurysm models with a height of 10 mm and neck sizes of 2.5 and 10 mm. Imaging was performed using a 1.5 T MR system with a head coil. Contrast-enhanced 3D MR angiograms were obtained using 3D ultrafast SPGR sequence with and without the MR Smartprep technique. Two-dimensional and 3D TOF MR angiograms were also obtained.

RESULTS

Contrast-enhanced multiphase 3D MR angiograms taken every 5 s after injection of contrast medium proved superior to the other MRA techniques for delineating lateral saccular aneurysm models. Contrast-enhanced 3D MRA images taken with inadequate delay after MR Smartprep trigger showed poor visualization of the aneurysm model.

CONCLUSION

Use of contrast-enhanced multiphase 3D MRA with ultrafast SPGR with shorter TR and TE resulted in clear images of the lateral saccular aneurysm model.

Software-triggered contrast-enhanced three-dimensional MR angiography of the intracranial arteries

OBJECTIVE

We investigated the effectiveness of software-triggered contrast-enhanced three-dimensional (3D) MR angiography in evaluating intracranial arteries.

SUBJECTS AND METHODS

We studied 38 patients with suspected brain lesions. Imaging was performed using a 1.5-T superconducting MR system with a commercially available head coil. To monitor signal intensity changes we used software to place a tracker volume at the basilar artery or the internal carotid artery. A 20-ml bolus of gadodiamide hydrate was administered through the antecubital vein at a rate of 2-4 ml/sec, followed by a saline flush. Three-dimensional MR angiography using a spoiled gradient-echo sequence with centric K-space ordering was triggered by the arrival of the contrast bolus in the tracker volume. Imaging times ranged from 12 to 20 sec. We used MR images to assess the effectiveness of contrast-enhanced 3D MR angiography in revealing intracranial arteries with minimal venous overlap.

RESULTS

The software triggered imaging on the arrival of the contrast bolus in 81.6% of examinations. In 77.6% of examinations, the resulting MR angiograms revealed intracranial arteries with minimal venous overlap.

CONCLUSION

Software-triggered contrast-enhanced 3D MR angiography with centric K-space ordering is a promising technique for viewing intracranial arteries.

Characterization of antiviral activity of lactoferrin against hepatitis C virus infection in human cultured cells

We recently found that bovine lactoferrin (bLF), a milk glycoprotein belonging to the iron transporter family, prevented hepatitis C virus (HCV) infection in human hepatocyte PH5CH8 cells, that are susceptible to HCV infection, and demonstrated that the anti-HCV activity of bLF was due to the interaction of bLF and HCV. In this study we further characterized the anti-HCV activity of bLF and the mechanism by which bLF prevents HCV infection. We found that bLF inhibited viral entry to the cells by interacting directly with HCV immediately after mixing of bLF and HCV inoculum. The anti-HCV activity of bLF was lost by heating at 65 degrees C, and other milk proteins (mucin, beta-lactoglobulin and casein) did not prevent HCV infection, indicating that bLF prevented HCV infection in a rather specific manner. Furthermore, we found that bovine lactoferricin, a basic N-terminal loop of bLF that is an important region for antibacterial activity, did not exhibit any anti-HCV activity, suggesting that some other region is involved in anti-HCV activity. We confirmed that prevention of HCV infection by bLF was a general phenomenon, because bLF inhibited HCV infection with all five inocula examined, and bLF inhibited HCV infection in human MT-2C T-cells, that were susceptible to HCV infection. In addition, infection with hepatitis G virus, which is distantly related to HCV, was prevented also by bLF. In conclusion, lactoferrin is a natural glycoprotein which effectively protects against HCV infection in hepatocytes and lymphocytes by neutralizing the virus.

Right ventricular cardiomyopathy showing right bundle branch block and right precordial ST segment elevation

A 73-year-old man who had a family history of sudden death, experienced syncope. His electrocardiogram (ECG) presented right bundle branch block and right precordial ST segment elevation which are findings identical with those in Brugada syndrome. The cardiac MRI showed right ventricular mild dilatation, and endomyocardial biopsy revealed fatty replacement of myocardial fibers. Though no ventricular tachyarrhythmias were induced during an electrophysiologic test, the effects on ECG of antiarrhythmic agents and autonomic modulations were similar to those in Brugada syndrome. This case may suggest the relationship between Brugada syndrome and right ventricular cardiomyopathy.

Stroke incidence and case fatality in Shiga, Japan 1989-1993

BACKGROUND

This paper describes incidence rates and case-fatality for sub-types of stroke using data collected in Takashima, Shiga, Japan, from 1989 to 1993 and compares these with similar registers in other parts of Japan.

METHODS

Registered patients included all residents of the county who experienced a first-ever stroke. Stroke was defined as sudden onset of neurological symptoms which continued for a minimum of 24 hours or led to death. Almost all such patients are hospitalized in this country. Early case fatality was defined as patients who died within 28 days of stroke onset. Diagnosis of stroke type was based on clinical symptoms as well as computed tomography (CT) scans.

RESULTS

Age-adjusted incidence rates for stroke per 100,000 population aged 35 years and older were 268.7 for men and 167.5 for women. The age-specific incidence rate of both cerebral infarction and cerebral haemorrhage increased with advancing age. The occurrence of cerebral infarction in men was twice as high as in women. The 28-day case fatality for all sub-types of stroke was 16.1% in men and 15.8% in women. Case fatality for cerebral infarction, cerebral haemorrhage, and subarachnoid haemorrhage was 10.7%, 22.4% and 28.6% respectively.

CONCLUSIONS

Takashima County has a moderately high stroke incidence rate and case fatality compared with other similar studies in Japan. The incidence rate of cerebral infarction in men is twice that in women, while other sub-types of stroke showed smaller differences. In order to decrease the incidence of stroke in Japan, greater efforts at primary prevention will be necessary, in particular, it is important to prevent cerebral infarction in men.

Evaluation of the pancreas: a comparison of single thick-slice MR cholangiopancreatography with multiple thin-slice volume reconstruction MR cholangiopancreatography

OBJECTIVE

The purpose of this study was to assess abilities of single thick-slice MR cholangiopancreatography and multiple thin-slice multiprojection volume reconstruction (MPVR) MR cholangiopancreatography to evaluate diseases in and around the pancreas.

SUBJECTS AND METHODS

Eighty-nine patients underwent both single and MPVR MR cholangiopancreatography using a single-shot fast spin-echo technique. Image quality (five-point scale), visualization of the common bile and pancreatic ducts (three-point scale), stenotic, dilatational, or cystic changes of the pancreatic ducts, and other pathologic findings were evaluated.

RESULTS

Image quality was high for single and MPVR MR cholangiopancreatography (4.1+/-0.7 and 4.5+/-0.6, respectively). Misregistration was noted in 19 patients with MPVR MR cholangiopancreatography. Ducts on and around the greater duodenal papilla and the common bile duct were revealed better using MPVR than single MR cholangiopancreatography (p < .05). Overall sensitivity, specificity, and accuracy for detection of stenosis of the main pancreatic ducts were 83.3%, 93.6%, and 88.8%, respectively, using single MR cholangiopancreatography and 76.2%, 97.9%, 87.6%, respectively, using MPVR MR cholangiopancreatography. Dilatation of the pancreatic ducts (100%) and cystic changes (n = 17 and n = 19, respectively) were well seen using either single or MPVR MR cholangiopancreatography. Although stenotic changes of the nondilated main pancreatic ducts and their branches were difficult to evaluate using single (62.5% and 14.3%, respectively) or MPVR (43.8% and 21.4%, respectively) MR cholangiopancreatography, single MR cholangiopancreatography better depicted ductal continuity.

CONCLUSION

For evaluation of the pancreas, single and MPVR MR cholangiopancreatography provide complementary data; thus, we recommend using a combination of these two MR cholangiopancreatography techniques.

Lactoferrin inhibits hepatitis C virus viremia in patients with chronic hepatitis C: a pilot study

Hepatitis C virus (HCV) is associated with the development of cirrhosis and hepatocellular carcinoma. We recently found that bovine lactoferrin, a milk protein belonging to the iron transporter family, effectively prevented HCV infection in cultured human hepatocytes (PH5CH8). We tested the hypothesis that lactoferrin inhibits HCV viremia in patients with chronic hepatitis C. Eleven patients with chronic hepatitis C received an 8-week course of bovine lactoferrin (1.8 or 3.6 g/day). At the end of lactoferrin treatment, a decrease in serum alanine transaminase and HCV RNA concentrations was apparent in 3 (75%) of 4 patients with low pretreatment serum concentrations of HCV RNA. However, 7 patients with high pretreatment concentrations showed no significant changes in these indices. This pilot study suggests that lactoferrin is one potential candidate as an anti-HCV reagent that may be effective for the treatment of patients with chronic hepatitis.

[Kinematic MRI using short TR single shot fast spin echo (SSFSE) in evaluating swallowing]

PURPOSE

To determine the utility of short TR single shot fast spin echo (SSFSE) MR imaging for evaluating swallowing.

MATERIALS AND METHODS

Five healthy volunteers underwent kinematic MR imaging of swallowing with a 1.5T MR scanner using the short TR (300 ms) SSFSE sequence. Twenty phases of sagittal sections were acquired within 6 sec, where the temporal resolution was 300 ms. For oral contrast medium, we used prune yogurt juice with Fe added.

RESULTS

The image contrast of short TR SSFSE was found to be somewhere like that of T1-weighted images. In all cases, both the buccal and pharyngeal stages of swallowing were successfully depicted. The Fe-added prune yogurt juice performed as a positive contrast medium and helped determine anatomical structures in the buccal stage.

CONCLUSION

Short TR (300 ms) SSFSE was useful in evaluating swallowing. The combined use of Fe-added prune yogurt juice was helpful in enhancing the surface of the oropharynx.

[Single shot fast spin echo (SSFSE)]

Single Shot Scan methods, which acquire all the necessary data for reconstruction with one excitation, are very useful methods to minimize motion artifacts. Single Shot Scan can be categorized in 2 groups, one is EPI method using gradient by Echo data acquisition, and another is SSFSE method using RF. SSFSE method is Single Shot FSE method using 0.5 NEX. SSFSE produces images with less motion artifacts and heavy PD and T2 images with high contrast. New RF reduces Echo Space and minimizes image quality degradation caused by Single Shot. SSFSE is useful for long T2 like MRCP. Long TE mode can be used with very long ETE even with 0.5 NEX. New applications development for Single Shot using RF is awaited in the future.

Technique for arterial-phase contrast-enhanced three-dimensional MR angiography of the carotid and vertebral arteries

Our goal was to evaluate whether contrast-enhanced three-dimensional MR angiography using the MR Smartprep technique would enable us to obtain arterial-phase MR angiograms of the carotid and vertebral arteries. The study included 35 patients with suspected lesions of the neck in whom the MR Smartprep technique was used for MR angiography performed with a 1.5-T superconducting system. The tracker volume was placed primarily in the middle part of the right common carotid artery. The imaging volume was placed in a coronal direction to include the carotid and vertebral arteries from the aortic arch to the skull base. A centric phase-ordering scheme was used. Imaging times were 20 to 38 seconds for 14 patients and 11 to 16 seconds for 21 patients. By using a smaller tracker volume and an imaging time of less than 16 seconds, we were able to achieve a 100% successful triggering rate and to delineate selectively arterial-phase carotid and vertebral arteries with almost no venous contamination. Contract-enhanced 3-D MR angiography with the MR Smartprep technique was useful for showing arterial-phase carotid and vertebral arteries selectively.

[Dynamic magnetic resonance dacryocystography using half Fourier single shot fast spin echo sequence]

Dynamic magnetic resonance dacryocystography (MRD) was implemented using 1.5T superconductive imager with a standard head coil. Prior to MRD, a pair of polyethylene microcatheters were inserted into the lower lacrimal canaliculi. Injecting a mixture of 6 ml of saline and 4 ml of xylocaine (0.5%) as a substitute for contrast medium, repeated measurement of thick section heavily T2 weighted image using half Fourier single shot fast spin echo (SSFSE) sequence was performed. MRD could well depict the pathologies of the lacrimal sac and the lacrimal duct in five cases of epiphora. It pinpointed the level of lacrimal duct obstruction, which was confirmed by both X-ray dacryocystography and intraoperative findings. Dynamic MRD is a reliable method of diagnosing nasolacrimal duct obstruction without using ionizing radiation or chemical contrast medium.

The surface color measurement of major tissues of silky fowls and White Leghorns

This report concerns the surface color of major organs of the silky fowl and White Leghorn chicken as measured by a color analyser. Although it is obvious that organs of the silky fowl look darker than those of the white leghorn, the color measurement of these organs has not yet been reported. The authors found that color differences between silky fowls and White Leghorns were significant in lung, brain, skin, and gluteal muscle. But the surface color of kidney and cardiac muscle of the two groups of fowl was not significantly different. The present data were represented in color charts.

Energy dispersive X-ray fluorescence spectrometry of major tissues of silky fowls

This report is to survey elements in frozen or freeze-dried samples of major organs of silky fowls with energy dispersive X-ray fluorescence spectrometer (EDXRF). There was not essential difference between frozen and freeze-dried samples. Of major elements, P. S, K, and Cl were always detected and Mn, Fe, Ca, and Zn were detectable in certain organs. Iodine was detected in thyroid glands. Occasionally Br was detected. The duration of freeze drying, 24 hr or 7 days, did not make significant difference in elemental analysis.

Nitrogen dioxide in indoor ice skating facilities: an international survey

An international survey of nitrogen dioxide (NO2) levels inside indoor ice skating facilities was conducted. One-week average NO2 concentrations were measured inside and outside of 332 ice rinks located in nine countries. Each rink manager also completed a questionnaire describing the building, the resurfacing machines, and their use patterns. The (arithmetic) mean NO2 level for all rinks in the study was 228 ppb, with a range of 1-2,680 ppb, based on a sample collected at breathing height and adjacent to the ice surface. The mean of the second indoor sample (collected at a spectator's area) was 221 ppb, with a range of 1-3,175 ppb. The ratio of the indoor to outdoor NO2 concentrations was above 1 for 95% of the rinks sampled, indicating the presence of an indoor NO2 source (mean indoor:outdoor ratio = 20). Estimates of short-term NO2 concentrations indicated that as many as 40% of the sampled rinks would have exceeded the World Health Organization 1-hour guideline value of 213 ppb NO2 for indoor air. Statistically significant associations were observed between NO2 levels and the type of fuel used to power the resurfacer, the absence of a catalytic converter on a resurfacer, and the use of an ice edger. There were also indications that decreased use of mechanical ventilation, increased number of resurfacing operations per day, and smaller rink volumes were associated with increased NO2 levels. In rinks where the main resurfacer was powered by propane, the NO2 concentrations were higher than in those with gasoline-powered resurfacers, while the latter had NO2 concentrations higher than in those using diesel. Rinks where the main resurfacer was electric had the lowest indoor NO2 concentrations, similar to the levels measured outdoors.

Diffusion-weighted imaging of the human optic nerve: a new approach to evaluate optic neuritis in multiple sclerosis

The apparent diffusion coefficient (ADC) in the optic nerve was measured from diffusion-weighted magnetic resonance imaging using an intravoxel incoherent motion (IVIM) sequence. The subjects were seven normal volunteers and eight patients with multiple sclerosis (MS) with a total of four optic nerves with acute neuritis and nine nerves with chronic neuritis. The mean ADC (4.18 +/- 1.13 x 10(-3) mm2/s, n = 9) in the optic nerves with chronic neuritis was significantly higher than that in normal volunteers (1.56 +/- 0.675 x 10(-3) mm2/s, n = 14) and that in the nerves with acute neuritis (0.94 +/- 0.43 x 10(-3) mm2/s n = 4) (P < 0.001). The ADC is useful in assessing MS foci in the optic nerves.

MR angiography of the renal artery: comparison of breath-hold two-dimensional phase-contrast cine technique with the phased-array coil and breath-hold two-dimensional time-of-flight technique with the body coil

Breath-hold 2D phase-contrast (PC) cine MR angiography with a phased-array coil and 2D time-of-flight (TOF) MR angiography were performed in the renal arteries and their findings were compared. Breath-hold 2D thin slice PC and TOF MR angiography were performed in 10 normal volunteers for renal arteries. A PC technique with k-space segmentation was utilized with the phased-array coil. A PC technique provided visualization of the renal artery more distally than a TOF technique (4.8 +/- 0.5 cm vs. 3.7 +/- 0.8 cm). With cardiac triggering, distal renal arteries were well demonstrated in PC MR angiography. On PC images, up- or downward movements of the mid to distal renal arteries with aortic pulsatility were recognized. The quality of the images was better with the PC than with the TOF technique (3.4 vs. 2.7). The mid to distal portions of the renal arteries translationally move with aortic pulsatility. To consistently visualize and evaluate them on MR angiography, cardiac triggering might be required to reduce the effects of pulsatile motions of the renal artery in the use of a phased-array coil.

Association between electrocardiographic ischemic abnormalities and ischemic heart disease risk factors in a Japanese population

This cross-sectional study was undertaken to investigate the association of electrocardiographic (ECG) ischemic abnormalities with ischemic heart disease (IHD) risk factors in a Japanese population. Resting ECGs of 1201 subjects (572 men and 629 women, aged 30 to 89 years), were coded independently by two coders according to the Minnesota Code. Blood pressure (BP) was recorded using a standard sphygmomanometer, and non-fasting serum total cholesterol and high-density lipoprotein cholesterol were measured. Codes 1.1 and 1.2 were classified as myocardial infarction and codes 1.3, 4.1-4.4, 5.1-5.3 and 7.1 were classified as ischemia. Prevalence of ECG with evidence of IHD (IHD ECG) was defined as myocardial infarction and ischemia together. Levels of risk factors were compared between subjects with IHD ECGs and those without IHD ECGs. Multiple logistic regression analysis was used to ascertain the associations between IHD ECG and risk factors. The prevalence of myocardial infarction in the total population was 1.5% and 0.7% in men and women, respectively and the prevalence of IHD ECGs was 10% and 11.3% in men and women, respectively. Systolic blood pressure (SBP) was consistently higher in subjects with IHD ECGs in the total population of both sexes (P < 0.001, P = 0.001 for men and women respectively). Diastolic blood pressure (DBP) was higher only in men with IHD ECGs (P = 0.002). In middle-aged men (aged 30-59 years), total cholesterol was considerably higher in subjects with IHD ECGs, although this relationship was statistically not significant. In multiple logistic regression analysis, SBP was independently associated with IHD ECGs in both sexes (P = 0.001). Associations between IHD ECGs with total cholesterol, alcohol intake and smoking were not statistically significant. This study showed that electro-cardiographic IHD evidences in Japanese are predominantly associated with blood pressure level in both sexes.

[Carcinoma of the renal pelvis and ureter following bladder carcinoma]

We followed 135 primary bladder carcinoma patients for at least 3 years. Subsequent carcinomas of the upper urinary tract were found in 5 patients (3.7 per cent) an average of 67 months after an initial treatment of the bladder tumors. Two patients underwent radical cystectomy and the remaining 3 patients received transurethral resections or partial cystectomy five to seven times for bladder lesions. Primary bladder tumor was multiple in all and one of them was accompanied by carcinoma in situ in the bladder and urethra. Except for one patient who presented with gross hematuria, four patients had no symptoms referable to the upper urinary tract tumor. However two of them had high stage disease. Positive urinary cytology was observed in only one patient. All patients underwent nephroureterectomy and the four got well but one died of acute heart failure. Regular urinary cytology and IVP should be done for an extended period of time for early detection of renal pelvic and ureter cancers in patients who had multiple and recurrent bladder cancers.

Attenuation of antifibrillatory effects of lidocaine by its metabolite, glycylxylidide: application of modulated receptor hypothesis

Lidocaine, one of the drugs effective in treating ventricular arrhythmias in acute myocardial infarction (AMI), sometimes loses its efficacy after prolonged administration, possibly owing to the counteraction of glycylxylidide, one of the metabolites of lidocaine, through modulation of binding of lidocaine to sodium channels. To determine whether glycylxylidide interferes with the antiarrhythmic action of lidocaine, we compared the antifibrillatory effects of lidocaine, glycylxylidide, and their combination in 14 anesthetized open-chest dogs. Although glycylxylidide alone prolonged intraventricular conduction time (CT) and did not affect ventricular effective refractory period (VERP), it had different effects when added to lidocaine; i.e., it had no effect on intraventricular conduction time but shortened VERP. Although glycylxylidide alone did not change ventricular fibrillation threshold (VFT), the increase in VFT induced by lidocaine was decreased by addition of glycylxylidide, possibly as a result of competition for the same cardiac sodium channels between lidocaine and glycylxylidide with similar onset but different offset kinetics, which may explain, at least in part, the drug-resistance phenomena that ensue from prolonged lidocaine administration.

Mechanism of interruption of atrial flutter by moricizine. Electrophysiological and multiplexing studies in the canine sterile pericarditis model of atrial flutter

BACKGROUND

Moricizine is said to have potent effects on cardiac conduction but little or no effect on cardiac refractoriness.

METHODS AND RESULTS

The effects of moricizine (2 mg/kg IV) on induced atrial flutter were studied 2 to 4 days after the creation of sterile pericarditis in 11 dogs. Ten episodes of stable atrial flutter before and after the administration of moricizine were studied in 9 dogs in the conscious, nonsedated state, and 7 episodes were studied in 6 dogs in the anesthetized, open chest state. In the conscious state, the effects of moricizine on atrial excitability, atrial effective refractory period, and intra-atrial conduction times were studied by recording during overdrive pacing of sinus rhythm from epicardial electrodes placed at selected atrial sites. Moricizine prolonged the atrial flutter cycle length in all the episodes, from a mean of 133 +/- 9 to 172 +/- 27 milliseconds (P < .001), and then terminated 7 of the 10 episodes. Moricizine increased the atrial threshold of excitability from a mean of 2.3 +/- 1.4 to 3.3 +/- 2.2 mA (P < .01) and prolonged intra-atrial conduction times (measured from the sulcus terminalis to the posteroinferior left atrium) from a mean of 58 +/- 6 to 64 +/- 5 milliseconds (P < .005). Prolongation of the atrial effective refractory period from 166 +/- 20 to 174 +/- 24 milliseconds (P < .05) was observed only at the sulcus terminalis site. In the open chest studies, administration of moricizine prolonged the atrial flutter cycle length from a mean of 150 +/- 15 to 216 +/- 30 milliseconds (P < .001) and then terminated the atrial flutter in all 7 episodes. As demonstrated by simultaneous multisite mapping from 95 bipolar sites on the right atrial free wall, the atrial flutter cycle length prolongation was either due to further slowing of conduction in an area of slow conduction in the reentrant circuit of the atrial flutter (5 episodes) or further slowing of conduction in an area of slow conduction plus the development of a second area of slow conduction (2 episodes). The change in conduction times in the rest of the reentrant circuit was negligible (10.9 +/- 8.7% of the total change). In all 7 episodes, the last circulating reentrant wave front blocked in an area of slow conduction.

CONCLUSIONS

Moricizine (1) prolongs the atrial flutter cycle length, primarily by slowing conduction in an area of slow conduction in the reentrant circuit, (2) terminates atrial flutter by causing block of the circulating reentrant wave front in an area of slow conduction of the reentrant circuit, and (3) effectively interrupts otherwise stable atrial flutter in this canine model. The reason for these effects of moricizine are not readily explained by its effects on global atrial conduction times and refractoriness studied during sinus rhythm. Local changes in conduction in an area(s) of slow conduction are responsible for both cycle length prolongation and atrial flutter termination rather than the traditional wavelength concept of head-tail interaction.

A quantitative estimation of electric current due to myocardial injury

Myocardial injury causes electric current at the border of injured muscle and the surrounding intact region. In order to determine the magnitude of the injury current, experiments were performed with the isolated canine heart perfused with Tyrode's solution. The anterior descending branch of the left coronary artery was perfused selectively with high potassium (K+) solution and the resulting injury current was reflected in the ST shift of the orthogonal electrocardiogram, derived from the surface of a cubic container in which the heart was placed. After measurement of the ST vector with different K+ concentrations, the heart has fixed with formalin and the injury zone was delineated with serial sections. The boundaries of the selectively perfused region were reconstructed. The algebraic sum of orthogonal components of boundary surfaces determined the average direction normal to the boundary, which was found to be parallel with the ST vector. With increasing K+ concentrations, the ST shift became more marked. However, it was saturated at about 30 mEq/L K+. The maximum injury current, calculated from the saturated value of the ST magnitude, amounted to 0.10 mA.cm per unit area of the boundary surface. Additional experiments were performed with right ventricular papillary muscle preparations. Injuries were caused by a cotton pad containing high K+ solution placed in two directions to make the border along and across the long axis of the papillary muscle. The results indicate that the injury current in an anisotropic structure was essentially directed along the fiber orientation.

Characterization of double potentials in a functionally determined reentrant circuit. Multiplexing studies during interruption of atrial flutter in the canine pericarditis model

OBJECTIVES

We tested the hypothesis that double potentials recorded during atrial flutter in a functionally determined reentrant circuit reflect activation of the reentrant wave front around an area of functional conduction block.

BACKGROUND

The center of the atrial flutter reentrant circuit in the sterile pericarditis canine model is characterized by double potentials.

METHODS

We studied 11 episodes of atrial flutter in eight dogs during interruption of atrial flutter while pacing the atria. A multielectrode mapping system was used to record simultaneously from 190 electrodes on the right atrium (location of reentry).

RESULTS

Interruption of atrial flutter occurred when the orthodromic wave front from the pacing impulse blocked in an area of slow conduction in the reentrant circuit. The response of the double potential with interruption of atrial flutter depended on the location of the recording site relative to this area of block. Two types of response were seen. When the double potential was recorded orthodromically distal to this area of block, interruption of atrial flutter was associated with disappearance of the second deflection, and continued pacing after interruption of atrial flutter was not associated with reappearance of the second potential. When the double potential was recorded at a site orthodromically proximal to the area of block, interruption of atrial flutter was not associated with disappearance of the second potential, and when rapid atrial pacing was continued, the double potential remained despite disappearance of the atrial flutter reentrant circuit.

CONCLUSIONS

Double potentials represent functional conduction block in the center of the reentrant circuit, with each deflection of the double potential reflecting activation on either side of the area of functional block. The data also demonstrate that double potentials are not limited to a reentrant circuit, as they were recorded on either side of an area of block in the absence of such a circuit.

[A comparative study of the health conditions of elderly people living alone, elderly couples and the bedridden elderly at home in a rural area of Shiga Prefecture: special reference to morbidity rate and blood pressure, electrocardiograph and blood examination data]

For the purpose of obtaining basic data and for establishing a support system for elderly people with various health and social problems, a population survey was performed in 1990 to investigate the health and living conditions of elderly people living alone, elderly couples and the bedridden elderly in the town of Shigaraki, Shiga Prefecture. A total of 275 subjects (103 male, 172 female) 65 years of age and over were surveyed. The participation rate in this survey was 88.1%. Analysis of health conditions (morbidity rate, blood pressure, electrocardiograph and blood examination data) of elderly people living alone, elderly couples and the bedridden elderly produced the following: 1) Stroke was the main cause of being bedridden in men, while in women, bone and joint disease, especially fracture, was the main cause. 2) The combined prevalence of hypertension and borderline hypertension in elderly people living alone, elderly couples and the bedridden elderly was over 50%. The bedridden elderly had a lower prevalence than elderly people living alone and elderly couples. 3) Men in all of the above mentioned life styles, had a higher tendency of showing ECG abnormalities than women. The tendency for major ECG abnormalities was high for bedridden elderly, both male and female, with the tendency for men being higher. 4) In bedridden elderly, a tendency of higher prevalence of anemia, in both male and females, lower total serum cholesterol and triglyceride in males compared to elderly people living alone and in elderly couples, was observed.

Reappraisal of the coupling interval of ventricular extrasystoles as an index of ectopic mechanisms

OBJECTIVE

A mathematical model of modulated ventricular parasystole based on the relation between the coupling interval and the preceding RR interval was developed in an attempt to distinguish between parasystolic automaticity and other mechanisms. MATHEMATICAL MODEL: The relation between the coupling interval and the preceding RR interval was examined by plotting the coupling interval of each extrasystole against the preceding RR interval (coupling interval/RR diagram). The coupling interval/RR diagrams obtained from simulations with various modulation modes suggested that the parasystolic mechanism was likely when the dots representing extrasystoles appeared as discrete clusters. In contrast, a linear horizontal accumulation of dots indicated a non-parasystolic mechanism.

CLINICAL OBSERVATION

To verify the validity of the simulations, 24 hour electrocardiographic recordings from 60 patients with frequent ventricular extrasystoles (> 1000/day) were analysed to determine whether the extrasystoles showed intrinsic periodicity. Intrinsic periodicity indicative of a parasystolic mechanism was seen in 14 (93%) of 15 patients in whom the coupling interval/RR diagram was characteristic of a parasystolic mechanism. When the coupling interval did not change (variability < 200 ms) over a wide range of RR intervals (> 700 ms) intrinsic periodicity was never identified (0/17). Parasystolic automaticity was the likely mechanism in 11 of the remaining 28 patients (39.3%) in whom coupling interval/RR diagrams were not definitive.

CONCLUSION

These data indicate that definite patterns of coupling interval/RR diagrams can be used to distinguish between parasystolic and non-parasystolic mechanisms.

Role of anatomic architecture in sustained atrial reentry and double potentials

To determine the role of anatomic architecture in atrial flutter, electrophysiologic findings were correlated with anatomic features in a modified model of atrial flutter with ligation of the crista terminalis. Crista ligation in the middle right atrium prolonged intraatrial conduction time in a rate-dependent manner in 12 dogs, particularly in the low right atrium. With burst atrial pacing, unidirectional block occurred either in the low right atrium or in the interatrial septal region near the superior vena cava, leading to initiation of atrial flutter. Atrial activation mapping revealed a slow conduction area in the low right atrium where conduction had been delayed by crista ligation. On the intact tissues between the venae cavae, double potentials were recorded, a finding indicative of functional block in the center of the reentrant circuit. The interdeflection time of double potentials changed with the activation sequence of atrial flutter. This change could be explained by assuming that the functional center of the reentrant circuit leaned on the right atrial free wall side. Anatomic study demonstrated that areas of slow conduction, unidirectional block, and functional block in the center of the reentrant circuit were closely related to the location of the intact crista terminalis. In conclusion, the intact portion of the crista terminalis played an important role in the genesis of atrial flutter after blockage of longitudinal conduction through the crista.