The upper turnover site in the reentry circuit of common atrial flutter

The upper turnover site of the reentry circuit of common atrial flutter was examined with the uses of atrial activation mapping and extrastimulus techniques during atrial flutter. The findings suggest that it is anterior to the orifice of the superior vena cava, i.e., between the superior vena cava and tricuspid annulus.

Malignant plexiform tumor of the uterus: an unusual variant of epithelioid leiomyosarcoma

A 46-year-old woman with the complaint of hypermenorrhea underwent hysterectomy for a presumed uterine myoma. The solid tumor in the myometrium was gray in color, was 4 cm in diameter, and showed hemorrhage and necrosis. Histologically, the tumor consisted of round or polygonal cells arranged in cords and nests, and its histological features closely resembled those of plexiform tumor which has been reported as a benign, epithelioid smooth muscle tumor of the uterus. In the tumor in our patient, however, mild nuclear atypia and two to three mitoses/10 high-power fields were present. Two months after the hysterectomy, the patient was found to have metastatic foci in the lumbar vertebrae and iliac bone, which contained tumor cells with the same histological features. Accordingly, the present tumor might be interpreted as a malignant plexiform tumor of the uterus, an unusual variant of epithelioid leiomyosarcoma.

Exercise performance after PTMC in mitral stenosis: the relation with hemodynamics, ventilatory response and skeletal muscle function

We examined the contribution of hemodynamics, ventilatory response and skeletal muscle function to the exercise performance after percutaneous transvenous mitral commissurotomy (PTMC). Nine patients with mitral stenosis (MS) underwent symptom-limited maximal ergometer exercise before, at 1 week and 3 months after PTMC. At 3 months after PTMC four patients (group 1) revealed an improved exercise performance (peak oxygen uptake (VO2) 747 +/- 145 to 1,039 +/- 175 ml/min; p < 0.01), and five patients (group 2) showed an unchanged exercise performance. Exercise performance in group 1 already increased at 1 week after PTMC. Peak cardiac output (Q) in group 1 increased (4.9 +/- 0.7 to 6.9 +/- 1.0 L/min, p < 0.05) at 3 months after PTMC. The slope of the minute ventilation (VE)-carbon dioxide production (VCO2) relation during exercise decreased at 1 week after PTMC (40.2 +/- 4.2 to 30.5 +/- 3.8, p < 0.05), and decreased slope of VE-VCO2 remained at 3 months after PTMC. However in group 2 these parameters did not change. There was a significant correlation between percent change of peak VO2 and percent change of peak Q from before to 3 months after PTMC (r = 0.84, p < 0.01). However there were no differences in reduction of mean pulmonary artery pressure, pulmonary vascular resistance and maximum isometric force (MIF) of left quadriceps between two groups. These findings suggest that the increased Q and improved excessive ventilation were important for increase in exercise performance in patients with MS after PTMC.

Clinical significance of measurements of antithyroid antibodies in the diagnosis of Hashimoto's thyroiditis: comparison with histological findings

Measurements of antithyroglobulin and antimicrosomal (antiperoxidase) antibodies have been performed widely for the clinical diagnosis of autoimmune thyroid diseases. The present study was designed to compare these antibody titers with histological findings of the thyroid in patients with diffuse goiter who were suspected of having Hashimoto's thyroiditis. One hundred and ten euthyroid or hypothyroid patients (10 males and 100 females; age 48 +/- 15 (SD) years old) with diffuse goiter were studied for the measurement of antithyroglobulin and antimicrosomal or antiperoxidase antibodies by a hemagglutination technique (TGHA and MCHA, respectively) and by a newly developed radioassay (TgAb and TPOAb, respectively). The antibody titers were compared with the histological findings obtained by needle biopsy. TgAb, TPOAb, TGHA, and MCHA were detected in 80 (96.4%), 61 (73.5%), 37 (44.6%), and 54 (65.1%) of 83 patients with histologically proven Hashimoto's thyroiditis, respectively, but in only one (3.7%) of 27 patients without any inflammatory changes in the biopsy specimen. In 55 patients with negative TGHA and MCHA, the TgAb positivity was more closely associated with the histological diagnosis of Hashimoto's thyroiditis than the TPOAb positivity was, the incidence of each antibody in Hashimoto's thyroiditis being 89.7% (26/29) and 27.6% (8/29), respectively. In conclusion, the histological diagnosis of Hashimoto's thyroiditis can most precisely be predicted by the newly developed radioassay for TgAb.

p53 mutation in B-cell lymphoid neoplasms with reference to oncogene rearrangements associated with chromosomal translocations

We investigated mutations of the p53 tumor suppressor gene in B-cell lymphoid neoplasms with reference to oncogene rearrangements associated with specific chromosomal translocations. These included 15 patients with a BCL1/PRAD1 gene rearrangement and/or PRAD1 overexpression, 45 with a BCL2 rearrangement, 2 with a BCL3 rearrangement, 24 with a BCL6 rearrangement, and 6 with both BCL2 and BCL6 rearrangements. Thirty-six patients lacked detectable oncogene rearrangements. Genomic DNA was isolated from involved tissues or leukemic cells obtained at diagnosis and/or at relapse, and established cell lines. Polymerase chain reaction-mediated single-strand conformation polymorphism analysis and direct sequencing were performed to analyze abnormalities of the p53 gene. We detected p53 gene alterations in 18 of 128 patients, representing 21 of the total 151 materials analyzed. In the total of 66 patients with an oncogene rearrangement studied at diagnosis, only one had a mutation; however, 6 of 37 patients studied at relapse showed p53 mutations. Sequential analysis revealed that the p53 mutation was closely associated with transformation from follicular lymphoma to large cell lymphoma, exclusively in BCL2-positive lymphoma cases. Two of 13 mutations observed in oncogene rearrangement-positive cases and cell lines were transitions at CpG dinucleotides. In contrast, the relationship between p53 mutations and clinical behavior in oncogene rearrangement-negative cases was variable; 5 patients including one with indolent follicular lymphoma were positive for p53 mutation at initial presentation, and 2 of the 5 showed prolonged disease-free survival. Our findings suggest that p53 alteration exhibits diverse functions in the development and progression of B-cell tumors related to the presence or absence of oncogene rearrangement, and that chemotherapy-related influences may be involved in the occurrence of progression-associated p53 mutations.

Tissue factor pathway inhibitor production by human mesangial cells in culture

Fibrin formation within the glomeruli has been observed in various forms of human and experimental glomerulonephritis and it may play an important role in progressive glomerular injury. Furthermore it has been hypothesized that glomerular fibrin deposition may occur through activation of either the intrinsic or extrinsic coagulation pathway. It has been demonstrated that a procoagulant activity (PCA) which is compatible with tissue factor is present in the glomeruli and becomes increased in human proliferative glomerulonephritis and in animal models of nephritis. Tissue factor pathway inhibitor (TFPI) regulates the extrinsic pathway of blood coagulation through its ability to inhibit tissue factor activity. TFPI is present in plasma and in platelets, and it is now thought to be produced mainly by endothelial cells. We examined whether human mesangial cells (HMC) could produce TFPI and attempted to clarify regulatory factors which affect TFPI production. Cultured HMC were used and TFPI in the cell supernatants was measured by ELISA using a specific antibody. Cultured HMC showed the production of TFPI. Immunoblot analysis revealed 40 kD protein of TFPI. The concentration of TFPI was significantly increased following the incubation with thrombin and heparin, including low molecular weight heparin, in a dose- and time-dependent manner. However, fetal calf serum, phorbol myristate acetate, lipopolysaccharide, IL-1 beta and tissue factor did not stimulate TFPI synthesis. Our data show that cultured HMC have the ability to produce TFPI which inhibits fibrin formation. It is possible that thrombin-induced enhancement of TFPI synthesis may be caused by the autoregulatory system of blood coagulation and that with heparin it may represent another anticoagulatory effect of heparin.

Salivary duct carcinoma: a clinicopathologic study of three cases with a review of the literature

Three cases of salivary duct carcinoma are presented. They occurred in a 60 year old man, a 66 year old man and a 57 year old woman. All of the lesions were located in the parotid gland. The tumor size ranged from 3 to 5 cm across the largest diameter. Facial paralysis was observed in two cases. Histologically, intraductal and invasive adenocarcinoma showing papillary, cribriform, and solid patterns with comedolike necrosis was observed. Immunohistochemically, the tumor cells were positive for keratin and epithelial membrane antigen. No myoepithelial cells were demonstrated within the tumor by staining for S-100 protein, alpha-smooth muscle actin or muscle specific actin. Ultrastructurally, intracytoplasmic lumina with microvilli, a moderate number of mitochrondria, lysosomes, and tight junctions were found. Regional lymph node metastasis was observed in one case, and distant metastasis developed in two cases. All of the patients were treated with adjuvant postoperative irradiation. One patient died of disease at 11 months after the initial diagnosis, another was alive with disease at 8 months, and the third patient was alive without disease at 2 years and 3 months. Salivary duct carcinoma should be differentiated from low-grade salivary gland carcinomas using morphologic and clinical criteria because of its poor prognosis even with aggressive therapy.

[Analysis of mutations and heteroplasmy at mitochondrial DNA 11778 using non-RI single strand conformation polymorphisms in Leber's hereditary optic neuropathy]

Leber's hereditary optic neuropathy(LHON) is a maternally inherited mitochondrial disease of an acute or subacute bilateral loss of central vision. G to A substitutions at nucleotide position 11778 in mitochondrial DNA(mt DNA) have been identified in approximately 40% to 90% of patients. In this study, regions containing mt DNA 11778 mutations were analyzed by polymerase chain reaction(PCR), non-RI single strand conformation polymorphisms(SSCP) and direct sequencing. In 26 visually affected patients, mt DNA 11778 mutations were detected in 9 patients (36.4%). In one pedigree of a LHON patient(L-6), four unaffected family members had heteroplasmy of the 11778 mutation using non-RI SSCP. Ratios of the heteroplasmy between wild type and mutant mt DNAs can be detected in non-RI SSCP and accurately quantified by video densitometric analyzer. Two types of novel polymorphisms, 11696 G to A and 11719 A to G, in the mt DNA region were also found in this non-RI SSCP analysis. Non-RI SSCP is an efficient and accurate method for diagnosis of mt DNA 11778 mutations and quantifying heteroplasmy in patients with LHON and pedigrees.

Sclerosing peritonitis associated with luteinized thecoma of the ovary

A unique case of bilateral luteinized thecomas of the ovary associated with sclerosing peritonitis is reported and the clinical and pathological features of this and previously reported cases are reviewed. The patient, 52 years of age, presented with abdominal distension and diarrhea. Pelvic imaging studies revealed bilateral ovarian tumors with ascites. Total abdominal hysterectomy and bilateral salpingo-oophorectomy with adhesiotomy of the small bowel were performed. Histologically, the ovarian tumor was composed of closely packed spindle to round-shaped cells, and within the spindle cell population, lutein-like cells were scattered singly or in clusters. Mitotic counts of spindle cells revealed 12 mitotic figures (MF) per 10 high-power fields (HPF) in one part of the left ovarian tumor, but other areas of the tumor showed less than 3 MF/10 HPF on average. The lesion from the resected small bowel showed prominent fibrosis, confined to the serosa with no evidence of metastasis from the ovarian tumor. The patient has undergone adhesiotomy with partial resection of the small bowel seven times since the first laparotomy because of the recurrent small bowel obstruction. The patient has survived with complications due to short bowel syndrome for 7 years after the initial surgery and so far no recurrence or metastasis of the ovarian tumor has been identified. The case reported here also supports the idea that luteinized thecoma of the ovary associated with sclerosing peritonitis may be a distinct clinicopathologic entity, in terms of the unique association and of the unique features of thecoma; that is, bilateral, hormonally inactive and apparently benign in spite of its highly mitotic activity. Additional attention should be paid to the patient's quality of life, which is often degraded by peritoneal fibrosis and small bowel obstruction.

Immunohistochemical study of metallothionein in pancreatic carcinomas

Metallothioneins are a family of intracellular metalloproteins that have been thought to be involved in anticancer drug resistance. However, the role of metallothioneins in pancreatic cancer has not been investigated in detail. The immunohistochemical localization of metallothionein was examined in normal human adult pancreas tissue and in 75 pancreatic duct cell carcinomas, using monoclonal anti-metallothionein antibody. Furthermore, in vitro studies on the sensitivity of pancreatic cancer to cisplatin were performed in 10 cases of pancreatic carcinoma. Metallothionein staining was weakly positive in the acinar and islet cells and intralobular ducts but was negative in the large pancreatic ducts. In pancreatic carcinomas, metallothionein staining was diffusely positive in 6 (8%), focally positive in 25 (33%) and negative in 44 (59%) of the 75 pancreatic carcinomas. The expression of metallothioneins in pancreatic tumors was related to metastasis, poor prognosis and poor histological grading (poorer glandular differentiation and nuclear anaplasia). The in vitro study of tumor sensitivity to cisplatin showed no significant correlation between metallothionein expression and resistance to cisplatin. Metallothionein-positive pancreatic carcinoma will be potentially highly malignant or acquire an enhanced ability to produce metallothioneins as the malignant potential increases. The expression of metallothionein could be a prognostic indicator in pancreatic carcinomas.

Metastasizing uterine leiomyoma. A case with cardiac and pulmonary metastasis

A case of histologically benign cardiac and pulmonary metastases from a uterine leiomyoma in a 45-year-old woman is reported. The solitary cardiac tumor consisted of five lobules with a stalk attached to the anterior papillary muscle of the right ventricle, which occupied the right ventricular cavity and almost completely obstructed the pulmonary main trunk in the systolic cycle. Multiple small nodules were found throughout both lungs. The cardiac tumor was resected at open heart surgery and open lung biopsy of the pulmonary lesion was simultaneously performed. Both of them were histologically identical to the apparently histologically benign uterine leiomyoma which had been resected five years previously. Based on the clinical and laboratory findings, it is postulated that antegrade metastases via the venous system resulted in the cardiac metastasis from the uterine leiomyoma and the secondary pulmonary metastasis from the cardiac tumor. In contrast to the light microscopic findings, ultrastructural examination suggested the possibility of malignancy associated with the presence of immature smooth muscle cells. This is the first reported case of a so-called benign metastasizing leiomyoma occurring in the heart.

Rearrangement of the BCL6 gene in B-cell lymphoid neoplasms: comparison with lymphomas associated with BCL2 rearrangement

We report a series of B-cell neoplasms with regard to rearrangement of the BCL6 gene on chromosome band 3q27. Southern blot analysis using probes from the major translocation cluster (MTC) region of the BCL6 revealed rearrangement in 21/197 patients (10.7%) with B-cell neoplasms studied at presentation, and 11/25 patients (44%) first studied at relapse. In non-Hodgkin's lymphoma (NHL) studied at diagnosis, rearrangements of the BCL6 gene were not closely associated with a specific histopathologic subtype but distributed in subcategories in the Working Formulation. The incidence in follicular lymphoma was 12.1%, with significantly higher frequency in mixed and large cell subtypes, and that in diffuse aggressive lymphoma was 14.1%. Comigration analysis using probes from the immunoglobulin genes revealed association of the BCL6 gene with one of the three immunoglobulin loci in 9/25 cases analysed. A comparative study between NHL associated either with BCL2 or BCL6 rearrangement showed that advanced disease and bone marrow involvement were more frequent in BCL2(+) NHL. In contrast, extranodal involvement was more frequently observed in the BCL6(+) NHL. The survival curve of BCL6(+) NHL was characterized by a rapid decline followed by a plateau. Of the total of 32 BCL6(+) patients, six carried both BCL2 and BCL6 rearrangements; five of these six showed clinicopathological properties characteristic of follicular lymphoma, suggesting that the presence of the two genetic abnormalities does not necessarily have synergistic effects on malignant phenotypes. The high level of BCL6 expression in follicular lymphoma cell lines carrying a BCL2 rearrangement suggests that the deregulated BCL2 gene may have an effect on the development of genetic abnormalities of the BCL6 gene. The present study suggests that BCL6 gene rearrangement is primarily involved in large cell lymphoma irrespective of growth pattern of neoplastic cells, and that BCL6(+)BCL2(-) NHL could be curable with modern intensive chemotherapy.

Jak3 expression in glomerular epithelia of IgA nephropathy (IgA-N) patients

Jak3 is a member of the Janus kinase family which plays an important role in cytokine signal transduction. Jak3 associates the gamma(c) chain of receptors for IL-2, IL-4, IL-7, IL-9 and IL-15, and is essential for the signal transduction of these cytokines. We have isolated Jak3 kinase from renal mesangial cells and demonstrated the constitutive expression of Jak3 in glomeruli in vivo. To investigate the physiological and pathological role of Jak3 in glomeruli, we prepared anti-Jak3 antibody and analysed the localization of Jak3 in glomeruli of renal biopsy samples from various nephritis patients and normal subjects. Among 61 nephritis patients and four normal subjects investigated in the present study, Jak3 was selectively localized to glomerular epithelia of IgA-N patients (14/34 cases) and focal glomerulosclerosis patients (1/5 cases), but not detected in minimal changes (n = 6), membranous glomerulonephropathy (n = 7), crescentic glomerulonephritis (n = 4), lupus nephritis patients (n = 5), and normal subjects (n = 4). The intense immunoreactivity for Jak3 is significantly associated with the decrease in creatinine clearance (81.5 +/- 10.4 ml/min versus 104.3 +/- 29.6 ml/min; P < 0.05, Student's t-test) and the increase in level of serum creatinine (1.13 +/- 0.33 mg/dl versus 0.75 +/- 0.23 mg/dl; P < 0.01, Student's t-test) in IgA-N patients. Furthermore, gamma(c) chain was concomitantly expressed with Jak3 in glomerular epithelia in vivo and in vitro, suggesting that signal transduction via gamma(c)-Jak3 cascade may be involved in the pathogenesis of glomerular injury of IgA-N. Taken together with the recent findings that IL-4-secreting T lymphocytes in affected glomeruli injure glomerular epithelium, the responsiveness of glomerular epithelium for IL-4 may be pathologically enhanced in IgA-N.

Myocardial defect detected by 123I-BMIPP scintigraphy and left ventricular dysfunction in patients with idiopathic dilated cardiomyopathy

The present study examined the role of myocardial fatty acid in patients with idiopathic cardiomyopathy (DCM) by means of 123I-beta-methyl-p-iodophenyl pentadecanoic acid (123I-BMIPP) scintigraphy. Thirteen patients underwent 123I-BMIPP imaging, 201Tl imaging and echocardiography. All patients showed defective myocardial uptake of 123I-BMIPP and 201Tl. The left ventricular end-diastolic dimension (64.1 +/- 7.3 mm vs. 55.6 +/- 1.5 mm, p < 0.05) and end-systolic dimension (52.4 +/- 8.0 mm vs. 40.6 +/- 2.1 mm, p < 0.01) were significantly large in the defect group (123I-BMIPP defect score (DS) > 8) than the small defect group (DS < 7). The % fractional shortening (%FS) was also significantly smaller (18.6 +/- 3.8% vs. 27.0 +/- 3.3%, p < 0.01) in the large defect group. The 123I-BMIPP DS correlated statistically with %FS (r = 0.75, p < 0.01), while the 201Tl DS did not (r = 0.41, ns). We conclude that the patients with DCM revealed a 123I-BMIPP uptake defect and the defect reflected the degree of left ventricular dysfunction.

Deep negative T waves and abnormal cardiac sympathetic image (123I-MIBG) after the Great Hanshin Earthquake of 1995

The authors report the increased incidence of patients with deep negative T waves without Q wave after the Great Hanshin Earthquake of 1995. Subjects underwent cardiac metaiodobenzyl guanidine (123I-MIBG) imaging, 201Tl scintigraphy, and coronary angiography. Among 2,756 inpatients of the preceding 5-year period, 33 (1.2%) showed the deep negative T waves, whereas 6 of 94 (6.4%; P < 0.001) showed it after the earthquake. Four of six patients had an episode of chest pain. Cardiac metaiodobenzyl guanidine imaging revealed the extent defects in all six patients despite a minimal change of 201Tl image. In addition, cardiac metaiodobenzyl guanidine imaging washout rate was hastened not only in the defect area but also in the nondefect area, which suggested augmented sympathetic activation. Natural disasters can affect the frequency of deep negative T waves, which relate abnormal cardiac sympathetic imaging.

[Nucleotide sequences at intron 6 and exon 7 junction of fibroblast growth factor receptor 2 and rapid mutational analysis in Apert syndrome]

Apert syndrome, acrocephalosyndactyly Type I, is an autosomal dominant craniosynostosis comprising acrocephaly, facial dysmorphism and severe syndactyly of the hands and feet. Missense mutations at codons 252 and 253 at 5'-end on exon 7 of fibroblast growth factor receptor (FGFR) 2 have been identified in a large number of patients with Apert syndrome. In this study, nucleotide sequences on the intron 6 were determined by vector ligation-PCR and direct sequencing. Five DNA samples from sporadic Apert syndrome were examined by non-RI SSCP and direct sequencing using a primer pair of intron 6 and exon 7. All cases of the syndrome showed abnormal banding pattern in the SSCP and missense mutations from Ser to Trp at codon 252 of the FGFR2 gene. The non-RI SSCP and direct sequencing of the FGFR2 exon 7 from genomic DNAs may be a useful and rapid molecular means for clinical diagnosis of Apert syndrome.

[Frequent missense mutations of fibroblast growth factor receptor (FGFR) gene families in craniofacial syndromes in Japanese patients]

Craniofacial syndromes, including Crouzon syndrome, Pfeiffer syndrome, Jackson-Weiss syndrome, Apert syndrome and achondroplasia, have been indicated that syndromes were associated with mutations of fibroblast growth factor receptor (FGFR) gene families. In this report, seven Japanese patients with craniofacial syndromes, three Crouzon syndromes and four achondroplasias, were analyzed on FGFR2 and FGFR3 genes by non RI-SSCP (single strand conformation polymorphisms) and direct sequencing. Missense mutations of the FGFR3 exon 10, at codon 380 in two sporadic cases and codon 375 in two familial cases, were detected in all cases of achondroplasia. Mutations of the FGFR2 were noted in Crouzon and Apert syndromes. One of three Crouzon syndromes has a missense mutation at codon 342 on exon 9. Highly frequent mutations were clustered within some localized regions of the FGFR genes in craniofacial syndromes. Alterations in these receptors due to missense mutations would thus appear closely involved in pathogenesis of craniofacial syndrome. The non RI-SSCP and direct sequencing of the FGFR genes, shown in this report, may be an appropriate approach for diagnosis of these syndromes with extensive clinical application.

Double atrial responses to a single ventricular impulse in long RP' tachycardia

Double atrial responses (DARs) to a single ventricular impulse have been described in patients with long RP' tachycardia. To define the determinants for the occurrence of DARs, 8 cases with long RP' tachycardia were examined. The mechanism of long RP' tachycardia was the orthodromic atrioventricular reciprocating tachycardia (AVRT) involving a slow conducting concealed accessory pathway in 4 cases and uncommon (fast-slow) type of atrioventricular nodal reentrant tachycardia (AVNRT) in the other 4 cases. Programmed and rapid ventricular pacing was performed during sinus rhythm and also rapid ventricular pacing during tachycardia (i.e., entrainment). The retrograde effective refractory period (ERP) and the retrograde maximal 1:1 conduction rate of the fast and slow conducting pathways were examined. In 1 of the 4 cases with AVRT, DARs were observed during programmed and rapid ventricular pacing, performed during sinus rhythm and also during entrainment. In 1 of the 4 cases with AVNRT, DARs were observed only during entrainment. The determinants of DARs in cases with long RP' tachycardia were: (1) presence of two different retrogradely conducting pathways; (2) short ERP of the retrograde fast and slow conducting pathways and a short minimal pacing cycle length at which 1:1 ventriculoatrial conduction occurs via these pathways; (3) crucial conduction delay in the slow conducting pathway; and (4) preexisting antegrade unidirectional block in the slow conducting pathway or the antegrade block in the slow conducting pathway produced by collision with a previous retrograde impulse during entrainment.

Effect of the novel high affinity choline uptake enhancer 2-(2-oxopyrrolidin-1-yl)-N-(2,3-dimethyl-5,6,7,8-tetrahydrofuro[2,3-b] quinolin-4-yl)acetoamide on deficits of water maze learning in rats

The pharmacological properties of MKC-231 (2-(2-oxopyrrolidin-1-yl)-N- (2,3-dimethyl-5,6,7,8-tetrahydrofuro[2,3-b]quinolin-4-yl) acetoamide, CAS 135463-81-9) in comparison with an acetylcholinesterase (AChE) inhibitor, tacrine (CAS 1684-40-8) were studied. MKC-231(10(-10)-10(-6) moll) significantly increased high affinity choline uptake (HACU) when it was incubated with the hippocampal synaptosomes of ethylcholine mustard aziridinium ion (AF64A) treated rats, but not of normal rats. MKC-231 did not affect the AChE activity, [3H]- quinuclidinyl benzilate binding, and [3H]-pirenzepine binding. Oral administration of MKC-231 (1-10 mg/kg) significantly improved the learning deficits in the Morris' water maze of AF64A-treated rats, but it did not produce any significant side effects, like tremor, salivation or hypothermia, which were observed in rats treated with high doses of tacrine. Tacrine (0.1-3 mg/kg p.o.) failed to ameliorate the learning deficits in AF64A-treated rats. These results suggest that MKC-231 is a novel and quite unique compound, which improves the memory impairment induced by AF64A through the enhancement of HACU without any side effects at the effective doses.

Characteristics of slow conduction zone demonstrated during entrainment of idiopathic ventricular tachycardia of left ventricular origin

Idiopathic ventricular tachycardia (VT) with the right bundle branch block pattern and left-axis deviation has been shown to be due to reentry, but the property of the slow conduction zone within the reentry circuit is little understood. In 7 patients (mean VT cycle length [CL]: 361 +/- 49 ms), rapid pacing from the right ventricular outflow tract was performed during VT while recording electrograms at the early activation site in the left ventricle and at the right ventricular apex; also, conduction times from the pacing site to these recording sits (St-A and St-B intervals, respectively) were measured. Both constant fusion (except for the last paced beat) and progressive fusion were seen in all patients, indicating VT entrainment. The left ventricular site was captured orthodromically with an St-A of 394 +/- 57 ms at the pacing CL of 351 +/- 47 ms during entrainment, while the right ventricular apex was captured directly with an St-B interval of 63 +/- 19 ms. The St-A interval was gradually prolonged with the shortening of the pacing CL, whereas the St-B interval remained unchanged. VT was interrupted in all patients at the pacing CL of 279 +/- 39 ms. The effects of intravenous lidocaine (1 mg/kg) and verapamil (1 mg) were examined in 5 and 7 patients, respectively. Neither drug terminated VT but the VT-CL was increased to 369 +/- 57 ms after lidocaine (p <0.05) and to 413 +/- 69 ms after verapamil (p <0.05) (p <0.05 vs after lidocaine). The St-A interval was significantly increased after lidocaine (p <0.05) and after verapamil (p <0.05), while the St-B interval remained unchanged. A significant correlation between changes in St-A interval and VT-CL after verapamil was noted (p <0.001). In conclusion, the slow conduction zone of this VT shows tachycardia-dependent conduction delay, and the mechanism of this slow conduction involves mainly calcium channel-dependent conduction and partly depressed sodium channel-dependent conduction.