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Biomedical subjects

H Hayakawa

Publications and source records attributed to H Hayakawa.

At least 73 records · Page 4Linked to original sources

Uncommon atrial flutter originating in the left atrioventricular groove: emergence after successful catheter ablation for a left concealed accessory pathway.

This report describes a 49-year-old male with concealed Wolff-Parkinson-White syndrome in whom a true uncommon atrial flutter suddenly emerged 2 weeks after successful catheter ablation of a left-sided accessory pathway. The earliest atrial activation during the atrial flutter was recorded at the posterolateral mitral annulus 2 cm proximal to the previous successful ablation site for the accessory pathway. Two applications of radiofrequency (RF) current directed at the supravalvular mitral annulus could not terminate the atrial flutter. A subsequent delivery of RF current directed at the subvalvular annulus, where a local fragmented potential preceded the earliest atrial activation, eliminated the atrial flutter.

Animals↗

Incidence and clinical significance of junctional rhythm remaining after termination of radiofrequency current delivery in patients with atrioventricular nodal reentrant tachycardia.

The aim of this study was to elucidate the electrophysiologic characteristics and clinical significance of the accelerated junctional rhythm (JR) that remains after termination of radiofrequency (RF) current delivery during catheter ablation (CA) for atrioventricular nodal reentrant tachycardia (AVNRT). Fifty consecutive patients with AVNRT (21M, 29F, age 48 years) underwent RF-CA targeting the slow pathway. JR occurred at 124 out of a total of 236 ablation sites (53%) during the RF delivery. With 15 RF deliveries (6.4%, n=10), JR remained after termination of the RF delivery (Post-JR). The mean cycle length of the Post-JR immediately after termination of the RF delivery was 639+/-124 ms and its duration was widely distributed from 3 s to more than 1 h. The Post-JR exhibited a spontaneous rate deceleration and overdrive suppression by rapid atrial pacing. The JR during the RF delivery followed by Post-JR had a greater time span in which the JR appeared, compared with that without Post-JR. The Post-JR had less sensitivity(18 vs 96%), but greater specificity (97 vs 59%) and a positive predictive value (60 vs 39%) in predicting successful ablation compared with JR seen only during the RF delivery. It is concluded that the presence of Post-JR might be a reflection of the intense effect of RF energy on the nodal or peri-nodal tissue.

Adolescent↗

Correlation between atrial natriuretic peptide and baroreflex sensitivity in patients with congestive heart failure.

The aim of this study was to investigate the relationship between baroreflex sensitivity (BRS) and humoral factors in patients with congestive heart failure (CHF). BRS was assessed by the phenylephrine method in 16 patients with CHF and in 13 healthy controls. The CHF group was subdivided into 2 groups according to BRS (group A: <6 ms/mmHg, n=9; group B: > or =6 ms/mmHg, n=7). BRS was markedly depressed in CHF than in the controls (4.8+/-2.0 vs 8.3+/-3.6 ms/mmHg, p<0.01), and lower in group A than group B (3.3+/-1.3 vs 6.7+/-0.6 ms/mmHg, p<0.01). The plasma human atrial natriuretic peptide (h-ANP) level in group A was significantly higher than in group B (54.6+/-27.6 vs 18.0+/-7.4 pg/ml, p<0.01), and a significant inverse correlation was observed between plasma h-ANP and BRS (r=-0.635, p<0.01). However, there were no significant differences between the 2 groups in plasma catecholamine concentration, plasma renin activity and cardiac function by echocardiogram. These findings suggest that the elevation of endogenous ANP may also serve to compensate for impaired BRS in patients with CHF, in addition to its principal actions, such as diuresis and vasodilation.

Aged↗

[Possible contribution of alpha-adrenergic abnormalities to cerebral ischemia in the patients with sinus bradycardia. Analysis by pharmacologic autonomic nervous test].

BACKGROUND: Syncope of patients with bradyarrhythmia is perceived as severe sign of low cardiac output caused by bradycardia and as a major criteria for pacemaker implantation (PMI). However, it has been reported that PMI can not always prevent syncope; it has been suggested that not bradycardia but an abnormality of the autonomic nervous system plays a part in syncope. PURPOSE: To investigate the relation between autonomic nervous dysfunction and syncope in cases of sinus bradycardia (SB). SUBJECTS: Thirty-nine patients with SB were divided into two groups according to the presence (group S, n = 16, 46.9 +/- 20.0 years) or absence (group N, n = 23, 40.4 +/- 17.6 years) of syncope or presyncope. METHODS: Corrected sinus node recovery time (CSNRT) was measured by electrophysiologic study. Pharmacologic autonomic nervous tests were performed as follows in a quiet room. Increased HR by application of 0.04 mg/kg atropine (para-tone), and by 0.004 microgram/kg/min isoproterenol divided by 0.004 (beta-sens) were evaluated, beta-tone was obtained by subtracting HR after application of propranolol (0.2 mg/kg) from that of atropine. Basal beta-sympathetic activity was evaluated by beta-sec that was obtained by beta-tone/beta-sens. Increased SBP by application of 0.4 microgram/kg/min phenylephrine divided by 0.4 (alpha-sens) was evaluated. alpha-tone was obtained by subtracting minimum SBP after 0.2 mg/kg phentolamine from SBP after application of propranolol. Basal alpha-sympathetic activity was evaluated by alpha-sec, that was obtained by alpha-tone/alpha-sens. RESULT: There were no significant differences in basal clinical characteristics (age, sex, cardiac function) between the groups. The parameters of the functions of parasympathetic and beta-sympathetic receptors (para-tone, beta-sens, beta-tone, beta-sec) showed no significant differences between the groups, alpha-sens was attenuated (P < 0.01) and alpha-sec was augmented (P < 0.0001) significantly in group S. CONCLUSION: It was suggested that syncope or presyncope in SB patients could be attributed to failure of vasoconstriction mediated by alpha-sympathetic receptor but to severity of sinus node dysfunction.

Adolescent↗

[QT dispersion in premature beats produced by extrastimuli from the right atrium and right ventricle].

The difference between the maximum and minimum QT interval measured from a 12-lead electrocardiogram was defined as an index of spatial inhomogeneous repolarization of the ventricular myocardium. The causal relationship between QT dispersion and incidence of ventricular arrhythmias has been pointed out in various heart diseases, but until now it was discussed mainly related to sinus rhythm. QT dispersion in extrasystole may be more important in the development of arrhythmias. We examined 5 cases (mean age 34 +/- 12 years) with a history of paroxysmal supraventricular tachycardia, who underwent electrophysiologic study. Both atrial and ventricular premature stimuli were given at a basic cycle length of 600 msec respectively. The QT interval and the ventricular activation time (VAT) (period from premature test stimulus to the summit of QRS) of the premature beats were measured in a simultaneously recorded 12-lead electrocardiogram. QT dispersion (the difference between the longest QT interval and the shortest QT interval) and VAT dispersion (the difference between the longest VAT and the shortest VAT) were measured. In atrial premature beats, there were no significant changes in the QT dispersion or VAT dispersion when the coupling interval of the premature beats was shortened. In the ventricular premature beats, however, both the QT dispersion and the VAT dispersion tended to increase with the shortening of the coupling interval. We concluded that only a short coupled ventricular premature beat induces greater QT and VAT dispersion. A ventricular couplet with short coupling interval may contribute to the development of ventricular tachyarrhythmias.

Adult↗

Development of bronchus-associated lymphoid tissue in chronic hypersensitivity pneumonitis.

STUDY OBJECTIVES: Bronchus-associated lymphoid tissue (BALT) is well defined in animals. In humans, however, BALT has been reported to be inducible under pathologic conditions, such as chronic respiratory infection, although it is not present in healthy adults. Thus, induced BALT is considered to be involved in the mucosal immunity of the human lung under these conditions. However, there have been few studies to investigate BALT development in hypersensitivity pneumonitis. The aim of this study was to examine the presence of BALT in hypersensitivity pneumonitis, especially in its chronic form. METHODS: The subjects included five patients with chronic hypersensitivity pneumonitis (CHP) diagnosed from clinical and histologic findings. We investigated histologically the development of BALT in these patients. Further, the cellular distribution of BALT was also examined by immunohistochemistry. RESULTS: BALT was present in three of five patients with CHP. Immunohistochemical examination revealed the follicular area of BALT to be composed mainly of B cells, while the parafollicular area comprised predominantly T cells. Centroblasts located in the germinal center of BALT expressed Ki-67 antigen, a marker of cell proliferation, suggesting that these cells were actively proliferating after antigenic stimulation. Cells expressing bcl-2, which is present primarily on memory B cells, were confined to the follicular area, devoid of any germinal centers. S-100-positive, CD1a-negative interdigitating dendritic cells were observed in the dome area of BALT. CONCLUSIONS: These observations suggest that chronic antigenic stimulation and/or inflammation in CHP may cause BALT development, which, in turn, is likely to play an important role in the mucosal immune response of this disease.

Adult↗

[Survey of infective endocarditis in the last 10 years: analysis of clinical, microbiological and therapeutic features].

Infective endocarditis still presents problems with early diagnosis, selection of antibiotics and timing of surgical procedure despite modern antibiotics and investigative procedures. A retrospective study was performed to clarify the clinical and microbiological spectrum of recent infective endocarditis in the Japanese population in 38 patients with infective endocarditis (mean age 42.7 +/- 12.5 years) treated from March 1986 to March 1996. The portal of entry to bacteremia was unknown in most cases (57.9%), but the commonest identified portal was dental procedure (18.4%). Overall, the aortic valve was infected most frequently (44.7%) and followed by the mitral valve (36.8%). The most common complication of infective endocarditis were emboli (11/38, 28.9%) and congestive heart failure, NYHA class III and IV (14/38, 36.8%). Organisms were isolated from 26 of the 38 (68.4%) patients. Streptococcus viridans was the most frequent organism (34.2%), and then Staphylococcus aureus (13.2%). The blood culture positivity of microorganism was significantly higher in patients not receiving antibiotics than in those the received antibiotics (87.5% vs 50%, p < 0.05). The prevalence of streptococcal endocarditis decreased in the 1990s (1992-1996) in comparison with those in the 1980s (1986-1988). Multiple antibiotics were used frequently in 1990s and the sensitivity titer to piperacillin reduced from 3.0 in the 1980s to 1.8 in the 1990s. In contrast to reduction of streptococcal endocarditis, Staphylococcus aureus endocarditis has increased recently from 12.5% to 30.8%. The most common clinical features are valve destruction, low sensitivity of penicillin, and significantly higher in-hospital mortality. Surgical treatment was indicated most commonly in cases of uncontrollable heart failure, and infected valves were replaced during the active stage in 11/23 cases (47.8%). In-hospital mortality was higher in the medical treatment group than in the surgical group, but a long-term mortality of mean observation term 4.2 +/- 3.2 years was identical in the chronic phase. In patients with infective endocarditis and successful treatment in the acute stage, a long-term survival rate in medically treated patients was found almost comparable to surgically treated patients in our series. However, it should be emphasized that streptococcal endocarditis is being replaced by infection by Staphylococcus aureus, which is resistant to penicillin and requires intensive chemotherapy and proper decision at suitable timing for surgical therapy in the early stage.

Adult↗

[Serial cerebral computed tomography and magnetic resonance imaging in a case of hemolytic uremic syndrome with the complication of the central nervous system due to Escherichia coli O157:H7].

We report serial cerebral computed tomography (CT) and magnetic resonance imaging (MRI) in a case of hemolytic uremic syndrome (HUS) with the complication of the central nervous system due to Escherichia coli O157:H7. Although initial brain CT was normal, follow-up CT and MRI revealed lesions in the white matter and bilateral basal ganglia, representing brain edema and infarcts, respectively. Especially, lesions in the bilateral basal ganglia were very unique. Serial CT and MRI findings are useful to understand the mechanism of the complications of the central nervous system associated with HUS.

Brain↗

Left coronary artery-left ventricular fistula with acute myocardial infarction, representing the coronary steal phenomenon: a case report.

A 59-year-old man presented with a left anterior descending coronary artery to left ventricular fistula manifesting as myocardial infarction, representing the coronary steal phenomenon. Electrocardiography showed poor R progression in leads V1 through V3. The biochemical markers of myocardial injury were elevated. Creatine kinase level was 509 IU/l, creatine kinase MB isoenzyme (CK-MB)47 IU/l, cardiac troponin T 0.62 ng/ml, myosin light chain 6.1 ng/ml, and myoglobin 142 ng/ml. Thallium-201 myocardial perfusion imaging with dobutamine stress showed a dobutamine-induced perfusion deficit of the anteroseptal wall of the left ventricle with 0.1 mV ST-segment depression in II, III, aVF, V5, and V6. The mean left anterior descending blood flow measured with the Doppler guidewire was increased from 211 to 378 ml/min. Selective coronary arteriography showed dominant left coronary artery with the contrast medium streaming into the left ventricle via a maze of fine vessels from the distal left anterior descending coronary artery. No critical stenosis of the left anterior descending coronary artery was observed. Administration of acetylcholine 100 micrograms into the left coronary artery did not induce vasoconstriction of that artery. The fistula terminating in the left ventricle was ligated surgically and the patient became free of chest pain. Thallium-201 myocardial perfusion imaging with dobutamine stress revealed no perfusion deficit of the anteroseptal wall of the left ventricle. The presence of coronary steal phenomenon was detected by dobutamine stress myocardial imaging.

Coronary Vessel Anomalies↗

Cancer cells overexpress mRNA of urokinase-type plasminogen activator, its receptor and inhibitors in human non-small-cell lung cancer tissue: analysis by Northern blotting and in situ hybridization.

The transcriptional localizations of urokinase-type plasminogen activator (uPA), its receptor (uPAR) and its inhibitors (PAI-1 and PAI-2), which are possibly involved in cancer metastasis, have not been determined in human lung cancer. To identify their regulation in primary non-small-cell lung cancer, we assayed mRNA levels by Northern blot analysis in 25 cases and determined the localizations of mRNA by in situ hybridization in 10 cases. The amounts of uPA and PAI-2 mRNA were significantly higher in cancerous relative to normal lung tissues. However, no significant difference was observed in uPAR and PAI-1 mRNA levels. All transcripts were present in cancer cells and were predominantly located in tumor edges in several cases. In addition, PAI-1 transcripts were more abundant in poorly and moderately differentiated carcinomas relative to well-differentiated carcinomas and PAI-2 transcripts were more abundant in squamous cell carcinomas than in adenocarcinomas. Thus, PAIs may be involved in modulation of malignant potency. Our results indicate that human non-small-cell lung cancer cells can autonomously express the mRNAs of uPA, uPAR and PAIs, which are possibly involved in metastasis.

Adenocarcinoma↗

Potential of Escherichia coli GTP cyclohydrolase II for hydrolyzing 8-oxo-dGTP, a mutagenic substrate for DNA synthesis.

MutT protein of Escherichia coli prevents the occurrence of A:T --> C:G transversion by hydrolyzing an oxidized form of dGTP, 8-oxo-7, 8-dihydro-2'-deoxyguanosine 5'-triphosphate (8-oxo-dGTP), which is produced by active oxygen species. In a search for mutT-related genes, we found that the ribA gene, encoding GTP cyclohydrolase II, is able to reduce the increased level of mutation frequency of the mutT strain to almost the normal level, provided that the gene product is overproduced. Purified preparations of Escherichia coli GTP cyclohydrolase II protein as well as the histidine hexamer-tagged recombinant GTP cyclohydrolase II protein efficiently hydrolyze 8-oxo-dGTP and 8-oxo-GTP, producing 8-oxo-dGMP and 8-oxo-GMP, respectively. dGTP was not hydrolyzed by these preparations. GTP cyclohydrolase II catalyzes conversion of GTP to 2, 5-diamino-6-hydroxy-4-(5-phosphoribosylamino)-pyrimidine, which constitutes the first step for riboflavin synthesis. The Km values for the three types of guanine nucleotides, GTP, 8-oxo-GTP, and 8-oxo-dGTP, were almost the same. In the mutT- background, ribA- cells showed higher spontaneous mutation frequencies as compared with that of ribA+ cells. Thus, GTP cyclohydrolase II, the ribA gene product, has a potential to protect genetic material from the untoward effects of endogenous oxygen radicals.

Base Sequence↗

Abnormality of alpha-adrenergic vascular response in patients with neurally mediated syncope.

Although diagnosis of neurally mediated syncope (NMS) using the head-up tilt (HUT) test has been established, the precise etiologic mechanism of NMS is still obscure. Previously, we reported the contribution of impaired alpha-adrenergic vascular response to syncope in patients with various arrhythmias. This study evaluates alpha-adrenergic vascular response in 21 NMS patients with syncope and a positive HUT test (80 degrees, 30 minutes, and low-dose isoproterenol, NMS group, mean age 31 +/- 14 years) and 21 control subjects (C group, 33 +/- 14 years) who had no evidence of syncope and no structural heart disease. After 30 minutes in a recumbent position, pharmacologic total autonomic blockade was attained using atropine and propranolol. Thereafter, increased systolic blood pressure with 0.4 microg/kg/min phenylephrine (designated as deltaBPphenyl) and decreased systolic blood pressure with 0.5 microg/kg/30 seconds of phentolamine (designated as deltaBPphent) were measured as indexes of alpha-adrenergic vascular sensitivity and activity, respectively. DeltaBPphenyl in the NMS group (70.0 +/- 37) was significantly less than that in C group (107 +/- 38, p <0.005). DeltaBPphent was significantly greater in the NMS group than in the C group (33.5 +/- 10 vs 21.0 +/- 14, p <0.005). Thus, decreased alpha-adrenergic vascular sensitivity and elevated alpha-adrenergic vascular tone were observed in patients with NMS. Although it is not known whether the mechanism causing NMS can be attributed to this abnormal alpha-adrenergic vascular response, the abnormality could at least contribute to augmenting the symptoms of NMS.

Adrenergic alpha-Agonists↗

Depressed heart rate variability and arterial baroreflex in conscious transgenic mice with overexpression of cardiac Gsalpha.

Recently, we developed a transgenic mouse with cardiac-specific Gsalpha overexpression (TG mouse), which exhibits enhanced postsynaptic beta-adrenergic receptor signaling, ultimately developing a cardiomyopathy. The goal of the present study was to determine whether cardiac Gsalpha overexpression alters autonomic cardiovascular control, which could shed light on the mechanism responsible for the later development of cardiomyopathy. Mean arterial pressure was increased (P<.05) in conscious, chronically instrumented TG mice (123+/-1 mm Hg) compared with age-matched wild-type (WT) control mice (103+/-1 mm Hg). Respiratory frequency was increased (P<.05) in TG mice (269+/-26/min) compared with WT mice (210+/-20/min). By use of telemetric techniques, baseline heart rate (HR) was elevated (P<.05) in conscious, untethered TG mice (696+/-13 bpm) compared with WT mice (568+/-28 bpm). Intrinsic HR, after propranolol and atropine or after ganglionic blockade with hexamethonium, was not different between TG and WT mice. Both the normal minute-to-minute and circadian variations of HR observed in WT mice were markedly blunted in TG mice. HR variability was assessed by the time-domain and frequency-domain methods. At baseline, time-domain analysis indices were reduced (P<.05) in TG mice compared with WT mice. Although the low frequency (LF) component was higher (P<.05) than the high frequency (HF) component in WT mice, the LF component was less (P<.05) than the HF component in TG mice. In addition, arterial baroreflex regulation of HR was markedly blunted in TG mice in response to both nitroglycerin-induced hypotension and phenylephrine-induced hypertension. The reduced LF/HF ratio in TG mice was surprising in view of enhanced beta-adrenergic signaling and may be due to reduced neural tone secondary to the elevated arterial pressure or alterations in arterial baroreflex control. Dobutamine infusion in WT mice also resulted in depressed HR variability. The combination of elevated baseline HR, arterial pressure, and respiratory frequency suggests that enhanced beta-adrenergic signaling in TG mice results in reduced HR variability, in terms of both minute-to-minute variability and the lack of circadian variations in HR. The lack of normal HR variability in general and the failure of HR to decline, even during sleep, may actually be critical mechanisms contributing to the ultimate development of cardiomyopathy in these animals.

Adrenergic beta-Agonists↗

Giant leiomyosarcoma of the remnant stomach: report of a case.

We describe herein the case of a 73-year-old woman who developed a giant leiomyosarcoma in the remnant stomach 4 years after undergoing a distal gastrectomy for gastric carcinoma. Abdominal ultrasonography and computed tomography revealed a huge tumor, 22 cm in maximum diameter, in the left hypochondrial region. Selective abdominal angiography showed a hypervascular tumor fed by the branches of the splenic artery and left inferior phrenic artery. The tumor arose from the posterior wall of the remnant stomach, and demonstrated marked extragastric growth and direct invasion of the pancreas, transverse colon, and diaphragm on the left side. Total resection of the remnant stomach with en bloc resection of these adjacent organs was subsequently carried out. We reviewed the Japanese literature on this extremely rare tumor and evaluated its clinical profile. In comparison with leiomyosarcoma of the unresected stomach, that of the remnant stomach more frequently showed endogastric-type growth and was accompanied by ulceration of the gastric mucosa. The prognosis of patients with leiomyosarcoma of the remnant stomach appears to be greatly affected by the presence of liver metastases and the tumor diameter, similar to that of patients with leiomyosarcoma of the unresected stomach.

Aged↗

Treatment of pancreas head carcinoma in a 91-yr-old man. Report of a case successfully treated with pylorus-preserving pancreatoduodenectomy.

The case of a 91-yr-old man who had a tumor of the pancreas head successfully resected is reported. He was admitted to our hospital because of obstructive jaundice, and then percutaneous transhepatic biliary drainage (PTBD) was performed. Cholangiography via PTBD tube showed marked stenosis of the bile duct in the head of the pancreas. Endoscopic retrograde pancreatography (ERP) showed obstruction of the main pancreatic duct in the head of the pancreas, and carcinoma in the head of the pancreas was diagnosed. Abdominal angiography showed stenosis of the celiac trunk caused by compression from the median arcuate ligament, but no tumor stain or encasement in the pancreas was detected. Because the patient had lived an extremely healthy life and had no serious concurrent disease before admission, laparotomy was performed. The tumor in the head of the pancreas was about 2 cm in diameter and restricted inside the pancreas. Pylorus-preserving pancreatoduodenectomy (PpPD) with regional lymph node dissection was performed. The tumor was 1.5 cm in its maximal diameter, and histopathologically was diagnosed as an invasive ductal carcinoma of the pancreas with moderately differentiated tubular adenocarcinoma. The patient had an uneventful postoperative course and now, 3 yr after surgery, he is doing very well and leading a normal daily life.

Aged↗

Influence of age at onset on the outcome of steroid-sensitive nephrotic syndrome.

To investigate whether age at onset of steroid-sensitive nephrotic syndrome (SSNS) is predictive of subsequent relapses, or influences outcome, we retrospectively studied 60 patients who were under 10 years of age at onset and were followed for over 10 years. They were divided into three groups according to age at diagnosis: group 1-3 (1.0-3.9 years at onset, n=24), group 4-6 (4.0-6.9 years at onset, n=22), and group 7-9 (7.0-9.9 years at onset, n=14). In the 51 patients with long-term remission, defined as remaining relapse-free over 3 years, the total number of relapses was significantly more in group 1-3 (n=18) than in group 4-6 (n=19), and the interval between onset and long-term remission was significantly longer. Group 4-6 and group 7-9 had fewer patients with active disease at 10 years, follow-up than group 1-3, as assessed by the Kaplan-Meier method. These data suggest that the age at onset of SSNS influences the clinical course (i.e., frequency of relapses) and the time to reach long-term remission. An age of less than 4 years at onset of SSNS is associated with greater likelihood for frequent relapses and a greater time interval to attain long-term remission.

Age of Onset↗

Arteriovenous malformation of the rectum: report of a case.

We report herein the case of a 38-year-old man found to have a rectal arteriovenous malformation (AVM). The patient was admitted to our hospital for investigation of fresh anal bleeding and general malaise. Barium-enema examination showed a slightly elevated lesion in the rectum, and a selective superior rectal angiogram subsequently revealed an AVM in the peripheral region of the superior rectal artery, which was presumed to be the cause of the anal bleeding. Colonoscopic examination disclosed a submucosal tumor-like lesion in the left posterior wall of the rectum, 3cm above the anal verge. After marking the boundaries by clipping, transanal resection of the lesion was performed. Histological examination revealed an irregularly expanded arteriovenous aggregation in the submucosal layer. The patient had a favorable postoperative course, and no residual AVM was seen on a postoperative selective inferior mesenteric arteriogram. There have been no signs of recurrence in the 2 years since his operation.

Adult↗