Identification of a Unique Amyloid Sequence in AA Amyloidosis of a Pig Associated With Streptococcus Suis Infection.

Here we report a pig with amyloid A (AA) amyloidosis associated with Streptococcus suis infection and identification of a unique amyloid sequence in the amyloid deposits in the tissue. Tissues from the 180-day-old underdeveloped pig contained foci of necrosis and suppurative inflammation associated with S. suis infection. Congo red stain, immunohistochemistry, and electron microscopy revealed intense AA deposition in the spleen and renal glomeruli. Mass spectrometric analysis of amyloid material extracted from the spleen showed serum AA 2 (SAA2) peptide as well as a unique peptide sequence previously reported in a pig with AA amyloidosis. The common detection of the unique amyloid sequence in the current and past cases of AA amyloidosis in pigs suggests that this amyloid sequence might play a key role in the development of porcine AA amyloidosis. An in vitro fibrillation assay demonstrated that the unique AA peptide formed typically rigid, long amyloid fibrils (10 nm wide) and the N-terminus peptide of SAA2 formed zigzagged, short fibers (7 nm wide). Moreover, the SAA2 peptide formed long, rigid amyloid fibrils in the presence of sonicated amyloid fibrils formed by the unique AA peptide. These findings indicate that the N-terminus of SAA2 as well as the AA peptide mediate the development of AA amyloidosis in pigs via cross-seeding polymerization.

Expression of Periostin in Normal, Atopic, and Nonatopic Chronically Inflamed Canine Skin.

In humans, periostin plays a critical role in the enhancement and chronicity of allergic skin inflammation; however, whether it is involved in the pathogenesis of canine dermatitis remains unknown. The aim of this study was to examine the expression patterns of periostin in healthy, atopic, and nonatopic chronically inflamed canine skin. Biopsy specimens from 47 dogs with skin disease and normal skin tissue from 5 adult beagles were examined by light microscopy, immunohistochemistry, and in situ hybridization. In normal skin, periostin was localized just beneath the epidermis and around the hair follicles. In chronically inflamed skin, periostin expression was most intense in the dermis with inflammatory cell infiltrates. In contrast, low levels of periostin were detected in acutely inflamed and noninflamed skin. Conversely, all canine atopic dermatitis tissues characteristically showed the most intense expression of periostin in the superficial dermis, particularly at the epidermal-dermal junction. In situ hybridization showed that periostin mRNA was broadly expressed in the basal epidermal keratinocytes, outer root sheath cells, and dermal fibroblasts in normal dog skin. High expression of periostin mRNA was observed in fibroblasts in dog skin with chronically inflamed dermatitis. Moreover, in some chronically inflamed skin specimens, periostin mRNA expression was increased in basal keratinocytes. The severity score of chronic pathologic changes and CD3+ cell number in the dermis were correlated with distribution pattern of periostin in the atopic skin. These data suggest that periostin could play a role in the pathophysiology of chronic dermatitis, including atopic dermatitis, in dogs.

Structural analysis and expression of the full-length cytochrome P450 gene operon in Campylobacter lari.

Two sets of PCR primers are constructed to clone the cytochrome P450 structural gene, including putative promoter and terminator structures, and its adjacent genetic loci in Campylobacter lari isolates. The putative open reading frames (ORFs) of the P450 genes from 11 C. lari isolates (n=5 for urease-negative (UN) C. lari; n=6 urease-positive thermophilic campylobacters [UPTC]) examined consisted of 1365 or 1371 bases (455 or 457 amino acid residues), differing from those of the other thermophilic campylobacters (1359 [453] for C. jejuni and C. upsaliensis; 1368 [456] for C. coli). Each of the putative ORFs from the 11 isolates examined was also shown to carry start and stop codons and ribosome binding sites. Two putative promoter structures, consisting of sequences at the -35- and -10-like regions were also identified upstream of the ORFs. A single copy of the P450 gene in the genome was identified with UN C. lari JCM2530(T) and UPTC CF89-12, based on Southern blot hybridisation analysis. In addition, when reverse transcription polymerase chain reaction (RT-PCR) analyses were carried out, the transcription of the P450 structural gene in C. lari organisms in vivo was confirmed. The transcription initiation site for the gene was also determined. High nucleotide sequence similarities (95.2-98.8%) of the full-length P450 structural gene were shown with each of the 12 C. lari isolates. The UN C. lari and UPTC organisms showed similar findings with the neighbour-joining method, based on the sequence information of the P450 structural gene.

RANKL increase in compressed periodontal ligament cells from root resorption.

The ligand receptor activator of NFkappaB (RANKL) plays an important role in osteoclast formation. However, very little is known about the relationship between external apical root resorption during orthodontic treatment and RANKL. We hypothesized that compressive force is responsible for RANKL formation and up-regulation of osteoclastogenesis in periodontal ligament (PDL) cells from patients with severe orthodontically induced external apical root resorption. RANKL and osteoprotegerin (OPG) production, TRAP-positive cells, and resorptive pits were determined. The increase of RANKL and the decrease of OPG were greater in the severe root resorption group than in the non-resorption group. The numbers of TRAP-positive cells and resorptive pits were also increased in the severe root resorption group than in the non-resorption group. These results support the hypothesis that the compressed PDL cells obtained from tissues with severe external apical root resorption may produce a large amount of RANKL and up-regulate osteoclastogenesis.

Degree of fatty acyl chain unsaturation in biliary lecithin dictates cholesterol nucleation and crystal growth.

To clarify factors involved in the formation of cholesterol gallstones, we studied the relationship between the degree of fatty acyl chain unsaturation of biliary lecithin and bile metastability. We used supersaturated model bile solutions (molar taurocholate/lecithin/cholesterol ratio (73:19.5:7.5), total lipid concentration 9 g/dl) that contained equimolar egg yolk or soybean lecithins or a sn-1 palmitoyl, sn-2 linoleoyl phosphatidylcholine. Gel permeation chromatographic studies showed that the vesicular cholesterol distribution and dimension were inversely related to the degree of unsaturation of the lecithin species, estimated by reverse phase, high-performance liquid chromatography. Differential interference contrast microscopy and assay of cholesterol crystal growth showed that a higher degree of fatty acyl chain unsaturation of the lecithin species was associated with a faster nucleation time and rate of crystal growth. Our results suggest that vesicular lecithins containing more unsaturated fatty acyl chains bind less tightly to cholesterol than lecithins containing predominantly saturated fatty acids, and that the biliary lecithin species dictates, in part, the nucleation and growth of cholesterol crystals in bile.

Long-term outcome of verapamil-sensitive sustained left ventricular tachycardia in patients without structural heart disease.

OBJECTIVES: This study attempted to determine the long-term outcome of verapamil-sensitive sustained left ventricular tachycardia in patients without apparent structural heart disease. BACKGROUND: Several types of idiopathic ventricular tachycardia have been reported, and their clinical, electrophysiologic and electropharmacologic characteristics are different. It is possible that the prognosis of each type of ventricular tachycardia might also be different. METHODS: We studied mortality and morbidity in 37 consecutive patients (27 male, 10 female; mean [+/- SD] age 33 +/- 14 years) with verapamil-sensitive sustained left ventricular tachycardia who had no apparent structural heart disease. Patients were followed up for 1 to 13 years (mean 5.8). Verapamil repeatedly terminated ventricular tachycardia in all patients. Ventricular tachycardia originated from the inferior and inferoseptal regions of the left ventricle in 33 patients and the superior and superioseptal regions in 4. Severity of ventricular tachycardia was classified according to the extent to which symptoms limited daily activities. Ventricular tachycardia was mild (minimal limitation) in 14 patients, moderate (some limitation) in 17 and severe (severe limitation) in 6. RESULTS: Fourteen patients with mild ventricular tachycardia were followed up without any drug therapy, and the ventricular tachycardia remained mild in all patients. Antiarrhythmic therapy was initiated empirically in the 23 patients with moderate and severe ventricular tachycardia (verapamil in 20, propranolol in 2, digoxin in 1). Moderate ventricular tachycardia became mild ventricular tachycardia after drug therapy in all patients, but the six patients with severe ventricular tachycardia showed no improvement. The six patients with severe ventricular tachycardia had nonpharmacologic therapy (cryosurgery in one, catheter ablation in four, antitachycardia pacing device in one). During the follow-up period, all patients remained alive except for one who died suddenly after implantation of an antitachycardia pacing device. CONCLUSIONS: 1) The long-term prognosis of verapamil-sensitive sustained left ventricular tachycardia in patients without apparent structural heart disease is good. 2) Verapamil is the drug of choice for alleviating symptoms, but nonpharmacologic therapy is necessary in some patients.

Frequency analysis of signal-averaged electrocardiogram in patients with right ventricular tachycardia.

OBJECTIVES: The purpose of this study was to analyze the frequency content of signal-averaged electrocardiograms (ECGs) in patients with idiopathic ventricular tachycardia of right ventricular origin and in patients with arrhythmogenic right ventricular dysplasia. BACKGROUND: The late potentials in the time domains are usually found in patients with arrhythmogenic right ventricular dysplasia. They are not usually found in patients with idiopathic ventricular tachycardia of right ventricular origin. METHODS: Fast Fourier transform analysis of signal-averaged ECGs was performed with the use of a Blackman-Harris window in 43 subjects: 20 normal volunteers (group I), 12 patients with idiopathic ventricular tachycardia of right ventricular origin (group II) and 11 patients with arrhythmogenic right ventricular dysplasia (group III), and the frequency spectrum was displayed in a three-dimensional graph. Area ratio (ratio of the area under the spectral plot from 40 to 120 Hz to the area from 0 to 120 Hz) was calculated in all subjects. RESULTS: Area ratio was significantly higher in group II than in group I (243 +/- 45 vs. 196 +/- 15, p < 0.01) and significantly higher in group III (396 +/- 51) than in group I or II (p < 0.001). The high frequency components in group II were confined within the QRS complex in the three-dimensional graph, whereas those in group III extended outside the QRS complex. CONCLUSIONS: Frequency analysis of the signal-averaged ECG with fast Fourier transform analysis can detect the high frequency components in patients with right ventricular tachycardia, including idiopathic ventricular tachycardia and arrhythmogenic right ventricular dysplasia.

Frequency-dependent electrophysiologic properties of ventricular repolarization in patients with congenital long QT syndrome.

OBJECTIVES: This study was performed to evaluate the frequency dependency of ventricular repolarization and the effect of epinephrine in patients with congenital long QT syndrome (LQTS). BACKGROUND: The efficacy of pacemakers in addition to antiadrenergic therapy in the treatment of congenital LQTS has been reported. METHODS: Monophasic action potentials were recorded from right and left ventricular endocardium during atrial pacing at heart rates from 70 to 140 beats/min at baseline and from 100 to 140 beats/min during epinephrine infusion (0.1 microgram/kg body weight per min) in 11 patients with congenital LQTS and 10 control patients. The response of monophasic action potential duration at 90% repolarization (MAPD90) and the dispersion of MAPD90 were examined. RESULTS: At baseline, both the MAPD90 and the dispersion of MAPD90 were significantly (p < 0.001) longer in the congenital LQTS group than the control group. The differences in these variables between the two groups significantly decreased (MAPD90: from 105 to 31 ms; dispersion of MAPD90: from 55 to 13 ms, p < 0.001) at heart rate was increased. Epinephrine prolonged the MAPD90 and increased the dispersion of MAPD90 significantly (p < 0.001) at all paced heart rates in the congenital LQTS group without frequency dependency but did not change in the control group. Thus, epinephrine increased the differences in these variables between the two groups. CONCLUSIONS: The repolarization abnormalities in congenital LQTS were attenuated by increasing the heart rate, which supported the efficacy of pacemaker therapy. However, during sympathetic stimulation, the effects of increased heart rate on these repolarization abnormalities were limited.

Effects of verapamil and propranolol on early afterdepolarizations and ventricular arrhythmias induced by epinephrine in congenital long QT syndrome.

OBJECTIVES: This study used monophasic action potentials to investigate the effects of verapamil and propranolol on epinephrine-induced repolarization abnormalities in congenital long QT syndrome. BACKGROUND: Early afterdepolarizations have been suggested to play a significant role in QT prolongation and ventricular arrhythmias in congenital long QT syndrome. Calcium channel blocking as well as beta-adrenergic blocking agents are reported to be effective in the management of this syndrome. METHODS: Monophasic action potentials from 2 to 4 sites were recorded simultaneously in eight patients with the long QT syndrome (22 sites) and in eight control patients (23 sites) and were obtained during constant atrial pacing 1) before epinephrine infusion; 2) during epinephrine infusion (0.1 microgram/kg body weight min); 3) after verapamil injection (0.1 mg/kg) during epinephrine infusion; and 4) after both propranolol (0.1 mg/kg) and verapamil injections. RESULTS: Early afterdepolarizations were recorded in two of the eight patients (2 of 22 sites) during the control state. During epinephrine infusion, early afterdepolarizations were recorded in six patients (six sites), and ventricular premature complexes were induced in three and torsade de pointes in one. Epinephrine prolonged 90% monophasic action potential duration from 348 +/- 48 (mean +/- SD) to 381 +/- 49 ms (22 sites, p < 0.0005) and increased the dispersion of action potential duration (difference between the longest and shortest action potential duration) from 36 +/- 20 to 64 +/- 34 ms (p < 0.005). Verapamil eliminated (two sites) or reduced (four sites) early afterdepolarizations and abolished ventricular premature complexes in two of the three patients as well as suppressing torsade de pointes. Verapamil shortened the action potential duration to 355 +/- 28 ms (p < 0.01 vs. epinephrine) and decreased the dispersion to 44 +/- 19 ms (p < 0.05 vs. epinephrine). Propranolol further eliminated (two sites) or reduced (two sites) early after depolarizations, abolished ventricular premature complexes in the remaining one patient and further shortened the action potential duration to 337 +/- 32 ms (p = 0.09 vs. verapamil). In the control patients, none of the early afterdepolarizations, ventricular arrhythmias or marked prolongations of action potential duration were induced by epinephrine, and neither verapamil nor propranolol changed repolarization variables. CONCLUSIONS: These results indicate that both verapamil and propranolol can improve repolarization abnormalities induced by epinephrine in congenital long QT syndrome.

Mode of onset of ventricular fibrillation in patients with Brugada syndrome detected by implantable cardioverter defibrillator therapy.

OBJECTIVES: We sought to demonstrate the mode of spontaneous onset of ventricular fibrillation (VF) in patients with Brugada syndrome. BACKGROUND: The electrophysiologic mechanisms of VF in Brugada syndrome have not been fully investigated. METHODS: Nineteen patients (all male, mean age 47 +/- 12 years) with Brugada syndrome were treated with an implantable cardioverter defibrillator (ICD). The implanted devices were capable of storing electrograms during an arrhythmic event. We investigated the mode of spontaneous onset of VF according to the electrocardiographic features during the episode of VF, which were obtained from stored electrograms of ICDs and/or electrocardiographic (ECG) monitoring. RESULTS: During a follow-up of 34.7 +/- 19.4 months (range 14 to 81 months), 46 episodes of spontaneous VF attacks were documented in 7/19 (37%) patients. The event-free period between ICD implantation and the first spontaneous occurrence of VF was 14.6 +/- 12.1 months (range 3.7 to 27.4 months). We investigated 33/46 episodes of VF, for which electrocardiographic features (10 to 20 s before and during VF) were obtained from ICDs and/or ECG monitoring in five patients. A total of 22/33 episodes of VF were preceded by premature ventricular contractions (PVCs), which were almost identical to the initiating PVCs of VF. Furthermore, in three patients who had multiple VF episodes, VF attacks were always initiated by the same respective PVC. The coupling interval of the initiating PVCs of VF was 388 +/- 28 ms. CONCLUSIONS: Spontaneous episodes of VF in patients with Brugada syndrome were triggered by specific PVCs. These findings may provide important insights into the pathophysiological mechanisms causing VF in Brugada syndrome.

Sympathetic stimulation produces a greater increase in both transmural and spatial dispersion of repolarization in LQT1 than LQT2 forms of congenital long QT syndrome.

OBJECTIVES: The study compared the influence of sympathetic stimulation on transmural and spatial dispersion of repolarization between LQT1 and LQT2 forms of congenital long QT sYndrome (LQTS). BACKGROUND: Cardiac events are more associated with sympathetic stimulation in LQT1 than in LQT2 or LQT3 syndrome. Experimental studies have suggested that the interval between Tpeak and Tend (Tp-e) in the electrocardiogram (ECG) reflects transmural dispersion of repolarization across the ventricular wall. METHODS: We recorded 87-lead body-surface ECGs before and after epinephrine infusion (0.1 microg/kg/min) in 13 LQT1, 6 LQT2, and 7 control patients. The Q-Tend (QT-e), Q-Tpeak (QT-p), and Tp-e were measured automatically from 87-lead ECGs, corrected by Bazett's method (QTc-e, QTc-p, Tcp-e), and averaged among all 87-leads and among 24-leads, which reflect the potential from the left ventricular free wall. As an index of spatial dispersion of repolarization, the dispersion of QTc-e (QTc-eD) and QTc-p (QTc-pD) were obtained among 87-leads and among 24-leads, and were defined as the interval between the maximum and the minimum of the QTc-e and the QTc-p, respectively. RESULTS: Epinephrine significantly increased the mean QTc-e but not the mean QTc-p, resulting in a significant increase in the mean Tcp-e in both LQT1 and LQT2, but not in control patients. The epinephrine-induced increases in the mean QTc-e and Tcp-e were larger in LQT1 than in LQT2, and were more pronounced when the averaged data were obtained from 24-leads than from 87-leads. Epinephrine increased the maximum QTc-e but not the minimum QTc-e, producing a significant increase in the QTc-eD in both LQT1 and LQT2 patients, but not in control patients. The increase in the QTc-eD was larger in LQT1 than in LQT2 patients. CONCLUSIONS: Our data suggest that sympathetic stimulation produces a greater increase in both transmural and spatial dispersion of repolarization in LQT1 than in LQT2 syndrome, and this may explain why LQT1 patients are more sensitive to sympathetic stimulation.

Immunocytochemical localization of immunoglobulins in the rat brain: relationship to the blood-brain barrier.

The central nervous system has been traditionally regarded as an immunologically privileged area. This feature has been in part attributed to the blood-brain barrier, which provides a restrictive interface to circulating immunoglobulins (IgG). Recent kinetic studies suggest that the barrier to immune proteins is not absolute, but rather may be regulated by a specific transfer mechanism. In this study, we confirm the presence of IgG in the central nervous system by immunocytochemistry and demonstrate a close anatomical relationship between the distribution of this protein and the blood-brain barrier. IgG was immunolocalized in the normal rat brain by using monoclonal and polyclonal antibodies to IgG and its subclasses. On the basis of an initial evaluation, the most appropriate antibodies and dilutions were selected for subsequent analyses. In the first study, IgG and albumin were immunolocalized in adjacent sections. In the second study, horseradish peroxidase (HRP) was given intravenously prior to sacrifice, in order to examine artifacts related to perfusion fixation. The distribution of HRP and IgG was then examined in adjacent sections. In the third study, IgG was immunolocalized in sections of brain after mild traumatic head injury. A monoclonal antibody to IgG2a and a polyclonal antibody to IgG were selected on the basis of specificity and consistent, mutual localization. Distinct, patchy, perivascular staining, infrequently associated with labeled neurons, was noted throughout the brain. Electron microscopy confirmed the perivascular localization; IgG was localized along the basal lamina of microvasculature and within the adjacent parenchyma. Albumin and HRP did not exhibit a similar pattern of perivascular immunostaining. After head injury, prominent immunostaining for IgG was observed in the injured hemisphere. In summary, these data indicate that the normal rat brain contains IgG, which dramatically increases after head injury. The distinct perivascular distribution in the normal brain suggests local microvascular permeability. This permeability is selective for IgG, since albumin does not share a similar perivascular localization. The neuronal staining which is closely associated with perivascular label may reflect one intracellular route for extravasated IgG.

Bradycardia-induced abnormal QT prolongation in patients with complete atrioventricular block with torsades de pointes.

Fourteen patients with complete atrioventricular block with or without torsades de pointes (TdP) were included in this study. They were divided into 2 groups, 6 patients with TdP (TdP[+] group) and 8 patients without TdP (TdP[-] group). The patients were evaluated at 2 different periods, before (acute period) and after (chronic period) pacemaker implantation. In the acute period, the QRS and heart rate during the escape rhythm were not significantly different between the 2 groups; however, the QT and QTc intervals were significantly longer in the TdP(+) group than in the TdP(-) group: 753 +/- 57.5 vs 635 +/- 78.4 ms (p less than 0.01) and 585 +/- 44.8 vs 476 +/- 58.3 ms (p less than 0.01). In the chronic period (greater than 2 months after pacemaker implantation), we changed the pacemaker rate from 90 or 100 beats/min to 50 beats/min and examined the QT interval changes in relation to the heart rate. The QT interval in the TdP(+) group was significantly prolonged compared with the TdP(-) group when the pacing rate was decreased less than or equal to 60 beats/min: 551 +/- 40 vs 503 +/- 36 ms at 60 beats/min (p less than 0.05), and 700 +/- 46 vs 529 +/- 43 ms at 50 beats/min (p less than 0.001). Patients with complete atrioventricular block with TdP had a bradycardia-sensitive repolarization abnormality and this characteristic remained after pacemaker implantation. The critical heart rate that induced abnormal QT prolongation in the TdP(+) group was less than or equal to 60 beats/min.

Reverse use dependence of human ventricular repolarization by chronic oral sotalol in monophasic action potential recordings.

Reverse use dependence of action potential duration and effective refractory period by chronic oral sotalol was demonstrated by monophasic action potential recordings in the human ventricle. There were no changes of the QRS duration over the cycle length, indicating that sotalol had no sodium channel blocking effects.

Diagnostic value of recovery time measured by body surface mapping in patients with congenital long QT syndrome.

The QT interval of the resting 12-lead electrocardiogram is normal or borderline in some patients with congenital long QT syndrome (LQTS). Recently, several in vivo experimental studies have shown that the time of maximum dV/dt in the ST-T segment is correlated with the time of local ventricular recovery. The purpose of this study was to examine the value of the body surface recovery time measured by 87-lead body surface mapping for detecting LQTS. Body surface mapping and 12-lead electrocardiography were performed simultaneously in 18 patients with LQTS and 40 controls of similar age and sex. The recovery time (RT), that is, the interval between QRS onset and the time of maximum dV/dt in the ST-T segment, was measured automatically by computer from each of the 87 mapping leads, and the corrected RT (RTc) was calculated by Bazett's method. The QT interval was measured from each of the 12 standard electrocardiographic leads, and the corrected QT (QTc) interval was also calculated. The maximum RT and RTc, the minimum RT and RTc, and the RT and RTc dispersions (difference between maximum and minimum RT and RTc in each patient) were significantly longer in the LQTS group than in the control group. In addition, a maximum RT of 390 msec, a maximum RTc of 430 msec 1/2, an RT dispersion of 170 msec, and an RTc dispersion of 170 msec1/2 separated the 2 groups completely (i.e., no overlap). The maximum QT and QTc, the minimum QT and QTc, and the QT and QTc dispersions (difference between maximum and minimum QT and QTc in each patient) were also significantly longer in the LQTS group than in the control group. However, the maximum QTc was normal (< or = 440 msec1/2) or borderline (< or = 460 msec1/2) in 5 of the 18 LQTS patients, and none of these parameters clearly separated the 2 groups. These results suggest that measurement of RT by 87-lead body surface mapping is useful for diagnosing latent or borderline LQTS.

Arrhythmogenic right ventricular cardiomyopathy underlies syndrome of right bundle branch block, ST-segment elevation, and sudden death.

Right ventricular morphologic and/or histologic abnormalities were present in 5 of 6 Japanese men with the Brugada syndrome. Results indicate that arrhythmogenic right ventricular cardiomyopathy may underlie the cardiac manifestations in the Brugada syndrome.

Differentiation between late potentials of right ventricular and of left ventricular origin.

The aim of this study was to determine whether late potentials of right and left ventricular origin could be differentiated with the use of a signal-averaging technique. Nineteen patients with both late potentials and recurrent sustained ventricular tachycardia were divided into 2 groups according to the origin of their late potentials. Group I consisted of 10 patients with late potentials that originated from the right ventricle. Group II consisted of 9 patients with late potentials originating from the left ventricle. Signal-averaged electrocardiograms (Marquette Electronics MAC I unit) were recorded using 3 bipolar and 3 augmented unipolar leads (the electrode positions were V1, V5 and V6R) with a band-pass filter of 100 to 300 Hz. The augmented unipolar V5 lead (aV5) was used for left-side recording and the augmented unipolar V1 lead (aV1) was used for right-side recording. In group I, the mean maximal late potential amplitude was larger in lead aV1 than in lead aV5 (5.1 +/- 2.5 vs 3.7 +/- 1.8 microV, p less than 0.005) and the maximal late potential amplitude was larger in lead aV1 in all except 1 patient. In group II, however, the mean maximal late potential amplitude was smaller in lead aV1 than in lead aV5 (4.0 +/- 3.0 vs 5.7 +/- 3.2 microV, p less than 0.005) and the maximal late potential amplitude was smaller in lead aV1 in all patients. Thus, the origin of late potentials (right ventricular vs left ventricular origin) can be determined by comparing the maximal amplitudes of late potentials in the right- and left-sided leads. This method might be useful in determining ventricular tachycardia origins.

Improved accuracy of the exercise electrocardiogram in detection of coronary artery and three-vessel coronary disease.

The study objective was to assess the widespread applicability of ST/HR slope for the modified Bruce exercise test using a computerized electrocardiogram (ECG); compare the usefulness of the ST/HR slope with standard ECG criteria in detection of coronary artery disease (CAD) and identification of three-vessel or left main CAD; and then develop a new, modified ST/HR score (MSHS) for improving the diagnostic accuracy of ST/HR slope. The studies were retrospective and prospective in design, conducted in referral-based cardiology clinics at a national cardiovascular center. A selected sample of 142 patients underwent exercise ECG and coronary angiography, as did a normal control group of 402 patients who were apparently free from CAD. Sixty three other patients who underwent coronary angiography were also studied prospectively. No limitations of medical treatment were exacted for the test except digitalis treatment. Linear regression analysis, from which ST/HR slope was derived, was done with seven measurements of HR and ST displacement at 60 ms from J point in leads a VF and V5 during 6 min before the end of exercise. MSHS was derived from a multiple regression model with peak HR (% maximum HR), ST index (ST depression + ST slope), and ST/HR slope. Although the usual ST criteria (sensitivity = 63 percent, specificity = 73 percent), ST index (71 percent, 80 percent), and ST/HR slope (70 percent, 97 percent) were equally accurate in detection of CAD, MSHS showed significantly improved sensitivity (88 percent) with similar specificity (81 percent). In identification of three-vessel or left main CAD, when compared with other criteria, ST/HR slope and MSHS provided improved diagnostic accuracy: sensitivity (74 and 78 percent, respectively), specificity (88 and 93 percent) and overall test accuracy (85 and 89 percent). The improved accuracy of ST/HR slope and MSHS was prospectively validated in 63 other patients. ST/HR slope was applicable to computerized ECG data for the standard treadmill test, and showed improved accuracy in detection of three-vessel or left main CAD. The new, modified ST/HR score more accurately predicted not only the presence but also the severity of CAD.

Diffuse brain injury induces local expression of Na+/myo-inositol cotransporter in the rat brain.

We studied expression of an osmoprotective gene, sodium/myo-inositol cotransporter (SMIT) in Marmarou's animal model for human diffuse brain injury by in situ hybridization and immunohistochemistry. In rats with diffuse brain injury, transient upregulation of SMIT mRNA was exclusively observed in the lateral area of pyramidal tract in lower brainstem. The expression was induced at 1 h after injury, peaked at 24 h, and returned to almost control levels at 48 h. Upregulated expression was found mainly in small glia-like cells. By immunohistochemistry using antibodies to phosphorylated mitogen-activated protein (MAP) kinases, inductions of phosphorylated p44/42 MAP kinase were also observed after diffuse brain injury. Interestingly, the distribution patterns of induced phosphorylated p44/42 MAP kinase were completely coincident with those of upregulated SMIT mRNA after diffuse brain injury. These results suggest that diffuse brain injury induces local expression of SMIT by activation of p44/42 MAP kinase cascade. The confined SMIT induction may reflect regional differences of damage and/or cellular differences in sensitivity to neuropathological stresses caused by this injury.

Alterations in the expression of the AQP family in cultured rat astrocytes during hypoxia and reoxygenation.

Aquaporins (AQPs) are a family of water-selective transporting proteins with homology to the major intrinsic protein (MIP) of lens [Cell 39 (1984) 49], that increase plasma membrane water permeability in secretory and absorptive cells. In the central nervous system (CNS), we detected the transcripts of AQP3, 5 and 8 in addition to the previously reported transcripts of AQP4 and 9 in astrocytes, of AQP3, 5 and 8 in neurons, of AQP8 in oligodendrocytes, and none of them in microglia using RNase protection assay and the reverse transcription-polymerase chain reaction (RT-PCR). Hypoxia evoked a marked decrease in the expression levels of AQP4, 5 and 9, but not of AQP3 and 8 mRNAs, and in astrocytes in vitro subsequent reoxygenation elicited the restoration of the expression of AQP4 and 9 to their basal levels. Interestingly, AQP5 showed a transient up-regulation (about 3-fold) and subsequent down-regulation of its expression within 20 h of reoxygenation after hypoxia. The changes in the profiles of AQP expression during hypoxia and reoxygenation were also observed by Western blot analysis. These results suggest that AQP5 may be one of the candidates for inducing the intracranial edema in the CNS after ischemia injury.