P1918Comparison of the clinical outcome of pulmonary vein isolation with cryoballoon and radiofrequency ablation for atrial fibrillation with pulmonary vein triggers

Background

Pulmonary vein isolation (PVI) using radiofrequency (RF) or cryoballoon (CB) has been an established treatment for atrial fibrillation. PVI using RF is the most common method with a rather complex technique of a point-by-point tissue heating and navigation of electro-anatomical-guided mapping system, and PVI with CB is also the common method with a relatively simple technique of freezing balloon occlusion. These 2 types of ablation are comparable in terms of the efficacy of the PVI procedure.

Purpose

The data on the clinical outcome of each AF type with PV triggers has been limited. We compared the outcome of success rate between RF and CB group with respect to each AF type, and further assessed the efficacy of pulmonary vein isolation for AF patients with the origin of only PV.

Methods

A total of 3402 AF patients (age 64±11; 2463 males) underwent initial PVI from May 2009 to July 2018 (PAF: 67%, non-PAF: 37%). Radiofrequency using irrigation-tip catheter was employed to 1796 patients since May 2009 (RF-PAF: 55%, RF-non-PAF: 45%). Second-generation cryoballoon was employed to other 1606 patients since September 2014 (CB-PAF: 81%, CB-non-PAF: 19%). In CB group, PV touch-up ablation with RF was needed for 113 patients (7%) (CB-PAF: 6%, CB-non-PAF: 13%; p<0.001). After PVI, additional ablation for non-PV foci was undergone after the induction by using isoproterenol infusion and rapid atrial pacing (RF-AF: 34%, CB-AF: 32%; p=0.107).

Results

In all PAF patients, AF free survival rate was significantly superior in CB group (2-years Kaplan-Meir event rate, CB 83.2%, RF 75.2%; log-rank p<0.001). The percentage of patients with non-PV foci was almost equivalent in both group (CB 30%, RF 31%, p=0.644). And in PAF patients with only PV-foci, AF free survival rate was significantly superior in CB group (2-years Kaplan-Meir event rate, CB 85.0%, RF 78.8%; log-rank p<0.001). On the other hand, in all non-PAF patients, AF free survival rate was almost equivalent in both non-PAF group (2-years Kaplan-Meir event rate, CB 65.5%, RF-non-PAF 70.0%; log-rank p=0.9). The percentage of patients with non-PV foci was almost equivalent in both group (CB 40%, RF 39%, p=0.731), And in non-PAF patients with only PV-foci, AF free survival rate was almost equivalent in both non-PAF group (2-years Kaplan-Meir event rate, CB 69.7%, RF 73.0%; log-rank p=0.376).

Conclusions

Our study showed better outcome of PVI with CB for PAF patients with PV triggers, and indicated the non-inferiority of PVI with CB for non-PAF patients with PV triggers to PVI with RF.

P6380The impact of coronary artery disease to predict mortality and neurological outcome in post-cardiac arrest patients

Background

Some studies reported that performing coronary angiography (CAG) for patients with out-of-hospital cardiac arrest (OHCA) is effective for the prognosis and neurological outcome. However, the impact of complexity of coronary artery disease (CAD) on CAG findings has not been evaluated sufficiently.

Purpose

We sought to investigate the complexity of CAD to predict the prognosis and neurological outcome in patients with OHCA.

Methods

A total of 1382 out-of-hospital cardiac arrest patients were transferred to our critical care center, of which 252 cardiovascular arrest patients achieving the return of spontaneous circulation (ROSC) were extracted from the institutional consecutive database between January 2015 and December 2018. Among those patients, we performed CAG for 160 patients. To predict mortality in hospital and neurological outcome at 30 days, we investigated basic patients' characteristics, pre-hospital information, coronary anatomical angiographical findings.

Results

Ventricular fibrillation (VF) (P=0.001), younger age (P=0.007), pre-hospital ROSC (P<0.001) and normal coronary artery on CAG findings (P=0.014) were associated with low 30-days mortality in hospital. VF (P=0.003), younger age (P=0.004), pre-hospital ROSC (P<0.001), bystander cardiopulmonary resuscitation (CPR) (P=0.043) and normal coronary artery (P=0.001) were associated with good neurological outcome (cerebral-performance-category (CPC) =1 or 2) at 30 days. We further investigated 100 patients who had any coronary artery stenosis on CAG findings. Among these patients, 55 patients (55.0%) had multi-vessel coronary artery disease and 29 patients (29.0%) had at least a chronic total occlusion lesion. VF survivor (P=0.035), without previous history of CAD (P=0.008), pre-hospital ROSC (P=0.013), and Syntax score (P=0.002) were associated with low 30-days mortality. In multivariate analysis, Syntax score (OR 0.94; 95% confidence interval (CI) 0.88–0.99; P=0.042) was independent predictor of mortality. Bystander CPR (P=0.001), pre-hospital ROSC (P<0.001) were associated with good neurological outcome at 30 days. Bystander CPR (OR 5.92; 95% CI 2.01–17.5; P<0.001) and pre-hospital ROSC (OR 9.22; 95% CI 3.34–25.5; P<0.001) were predictive for good neurological outcome.

Conclusions

OHCA patients with any coronary stenosis had high mortality and bad neurological outcome in comparison with those who had normal coronary arteries. OHCA patients with CAD had complex lesions such as multi-vessel disease or chronic total occlusion lesions. The coronary complexity in patients with OHCA was a predictor of in-hospital 30-days mortality. However, pre-hospital care such as bystander CPR and pre-hospital ROSC were the most important to achieve good neurological outcome at 30 days in the present study.

P2266The predictor of mortality and neurological outcome in out-of-hospital cardiac arrest patients with non-ST-segment elevation

Background

The prognosis of patients with out-of-hospital cardiac arrest (OHCA) remains poor. Coronary artery disease (CAD) is the most frequent cause of OHCA. The prompt evaluation and revascularization for coronary artery in OHCA patients with ST-segment elevation are recommended because they often have CAD. However, OHCA patients without ST-segment elevation also have any coronary stenosis in the non-negligible proportion. The predictor of mortality and neurological outcome in OHCA patients with no ST-segment elevation has not been sufficiently elucidated.

Purpose

We sought to investigate the predictor of mortality and neurological outcome at 30 days in OHCA patients without ST-segment elevation.

Methods

A total of 1382 out-of-hospital cardiac arrest patients were transferred to our critical care center, of which 252 cardiovascular arrest patients achieving the return of spontaneous circulation (ROSC) were extracted from the institutional consecutive database between January 2015 and December 2018. Among those patients, 183 patients' electrocardiogram after ROSC were without ST-segment elevation. We performed coronary angiography (CAG) for 103 patients, who were eligible for final analysis. To predict mortality in hospital and neurological outcome at 30 days, we investigated basic patients' characteristics, pre-hospital information, post-hospital care.

Results

Any coronary stenosis was founded in 50 patients (48.5%). Male (P=0.007), older age (P<0.001), past history of coronary artery disease (CAD) (P=0.037) and diabetes mellitus (P=0.087) were associated with coronary artery stenosis on CAG findings. Age (OR 1.05; 95% confidence interval (CI) 1.02–1.08; P<0.001), male (OR 5.33; 95% CI 1.37–20.7; P<0.001) were independent predictors of coronary artery stenosis. Among those who had stenosis, 34 patients (68.0%) survived and 27 patients (54.0%) achieved good neurological outcome (cerebral-performance-category (CPC) =1 or 2) at 30 days. Successful revascularization by percutaneous coronary intervention (PCI) was not associated with low mortality (P=0.77). Past history of CAD (P=0.014) and high Syntax score (P=0.030) were associated with mortality. Bystander cardiopulmonary resuscitation (CPR) (P-0.021), pre-hospital ROSC (P<0.001) was more frequent in patients with good neurological outcome. Pre-hospital ROSC (OR 14.7; 95% CI 3.1–69.3; P<0.001) was independently predictive for good neurological outcome.

Conclusions

Successful PCI for OHCA patients with no ST-segment elevation was not a predictor of mortality. CAD past history and complex CAD was associated with mortality. Pre-hospital information such as pre-hospital ROSC was important to achieve good neurological outcome.

P1919The assessment of the application and the efficacy of pulmonary vein isolation with cryoballoon for non-paroxysmal atrial fibrillation

Background

Pulmonary vein isolation (PVI) using second generation cryoballoon (CB) ablation has become an established treatment for paroxysmal atrial fibrillation (PAF) patients. On the other hand, PVI with radiofrequency (RF) has been an established treatment for non-PAF patients, in addition to PAF patients.

Purpose

The data on second generation CB ablation for non-PAF patients is limited. We assessed the application of PVI with CB for non-PAF patients and compared the outcomes of success rate, radiational time, and procedural time.

Methods

A total of 2632 AF patients (age 64±10; 1873 males) underwent initial PVI from September 2014 to June 2018. Second-generation CB was employed to 1587 patients (CB-PAF: 80%, CB-non-PAF: 20%) and RF using irrigation-tip catheter was employed to other 1045 patients (RF-PAF: 40%, RF-non-PAF: 60%). In CB group, PV touch-up ablation with RF was needed for 113 patients (7%) (CB-PAF: 6%, CB-non-PAF: 13%; p<0.001). After PVI, additional ablation for non-PV foci was undergone after the induction by using ISP infusion and rapid atrial pacing.

Results

AF free survival rate was almost equivalent in both non-PAF group (2-years Kaplan-Meir event rate, CB-non-PAF 66.3%, RF-non-PAF 69.8%; log-rank p=0.297). There was significantly difference in procedural time (CB-non-PAF 132±56min, RF-non-PAF: 189±52min, p<0.001), and radiation time (CB-non-PAF: 47±40min, RF-non-PAF: 75±31min, p<0.001). The percentage of patients with non-PV foci was significantly higher in CB group (CB-non-PAF 41%, RF-non-PAF 54%, p<0.001), and after excluding the patients with non-PV foci, AF free survival rate was almost equivalent in both group (2-years Kaplan-Meier event rate, CB-non-PAF 75.4%, RF-non-PAF 78.8%; log-rank p=0.577). On the other hand, in patients in CB, AF free survival rate was significantly superior in PAF group (2-years Kaplan-Meir event rate, CB-PAF 83.3%, CB-non-PAF 65.2%; log-rank p<0.001). There was significantly difference in procedural time (CB-PAF: 117±47min, CB-non-PAF: 132±56min, p<0.001), and radiation time (CB-PAF: 38±22min, CB-non-PAF: 46±27min, p<0.001). The percentage of patients with non-PV foci was significantly higher in non-PAF group (CB-PAF 30%, CB-non-PAF 41%, p<0.001), and after excluding the patients with non-PV foci, AF free survival rate was also significantly superior in PAF group (2-years Kaplan-Meier event rate, CB-PAF 85.1%, CB-non-PAF 69.8%; log-rank p<0.001).

Conclusions

For non-PAF patients with PV triggers, PVI with CB might be non-inferior to PVI with RF. Our study showed the efficacy of CB in terms of the shortening of procedural time, and the reduction of radiational exposure. PVI with CB for non-PAF patients was inferior to that for PAF patients.

Unique mechanisms of excitation energy transfer, electron transfer and photoisomerization in biological systems

We discuss unique mechanisms typical in the elementary processes ofbiological functions. We focus on three topics. Excitation energytransfer in the light-harvesting antenna systems of photosyntheticbacteria is unique in its structure and the energy transfer mechanism. Inthe case of LH2 of Rhodopseudomonas acidophila, the B850 intra-ringenergy transfer and the inter-ring energy transfer between B800 and B850take place by the intermediate coupling mechanism of energy transfer. Theexcitonic coherent domain shows a wave-like movement along the ring, andthis property is expected to play a significant role in the inter-ringenergy transfer between LH2's. The electron transfer in biological systemsis mostly long-range electron transfer that occurs by the electrontunneling through the protein media. There is a long-standing problem thatwhich part of protein media is used for the electron tunneling root. As aresult of our detailed analysis, we found that the global electron tunnelingroot is a little winded with a width of a few angstrom, reflecting theproperty of tertiary and secondary structures of the protein and it isaffected by the thermal fluctuation of protein structure. Photoisomerizationof rhodopsin is very unique: The cis-transphotoisomerization ofrhodopsin occurs only around the C11 = C12 bond in the counterclockwisedirection. Its molecular mechanism is resolved by our MD simulation studyusing the structure of rhodopsin which was recently obtained by the X-raycrystallographic analysis.

Spectral tuning of photoactive yellow protein

We report a theoretical study on the optical properties of a small, water-soluble photosensory receptor, photoactive yellow protein (PYP). A hierarchical ab initio molecular orbital calculation accurately evaluated the optical absorption maximum of the wild-type, as well as the lambda(max) values of 12 mutants. Electronic excitation of the chromophore directly affects the electronic state of nearby atoms in the protein environment. This effect is explicitly considered in the present study. Furthermore, the spectral tuning mechanism of PYP was investigated at the atomic level. The static disorder of a protein molecule is intimately related to the complex nature of its energy landscape. By using molecular dynamics simulation and quantum mechanical structure optimization, we obtained multiple minimum energy conformations of PYP. The statistical distribution of electronic excitation energies of these minima was compared with the hole-burning experiment (Masciangioli, T. [2000] Photochem. Photobiol. 72, 639), a direct observation of the distribution of excitation energies.

Diabetes mellitus decreases hippocampal release of neurotransmitters: an in vivo microdialysis study of awake, freely moving rats

Possible diabetes mellitus-induced changes in hippocampal monoaminergic activities were studied to understand the relationships between neurotransmitter levels and various abnormalities in freely moving diabetic rats. We used both experimentally (STZ rats) and spontaneously diabetic rats (WBN/Kob rats) as the diabetic animal model, and compared the findings with those obtained from non-diabetic rats (C rats). Measurement of neurotransmitters (serotonin and dopamine) was carried out using an in vivo microdialysis method. We found that: 1) the basal level of serotonin in the hippocampus was lowest in WBN rats, followed by STZ rats, then by C rats. The level of serotonin in WBN rats was about a half of that in C rats; 2) the basal level of dopamine was also significantly lower in the diabetic WBN and STZ rats than in C rats. The data show that diabetes mellitus decreases in the monoamine release from the hippocampus in both experimentally and spontaneously diabetic rats.

Annular pancreas complicated by carcinoma of the bile duct: diagnosis by MR cholangiopancreatography and endoscopic ultrasonography

It has been reported that annular pancreas should be evaluated for coexisting malignant tumors. However, no cases have been reported in which magnetic resonance cholangiopancreatography and endoscopic ultrasonography clearly demonstrated an annular pancreas complicated by bile duct carcinoma. We present a case that emphasizes the importance of magnetic resonance cholangiopancreatography and endoscopic ultrasonography in directly confirming a diagnosis of annular pancreas complicated by bile duct carcinoma.

Successful allogeneic blood stem cell transplantation for aplastic anemia in a patient with renal insufficiency requiring dialysis

A 27-year-old man with aplastic anemia and renal insufficiency requiring dialysis underwent allogeneic PBSCT. The preparative regimen consisted of melphalan, ATG and TLI. GVHD prophylaxis consisted of cyclosporine and prednisolone. He was dialyzed prior to administration of melphalan and at 24 and 72 h after it. Otherwise, the dialysis schedule was unchanged, at three times a week. Engraftment was rapid. Regimen-related toxicity was minimal. Pharmacokinetic parameters of melphalan were not significantly altered with its plasma half-life 1.5 h. Patients with renal failure can receive allogeneic HSCT, and a combination of melphalan, ATG and TLI may serve as an alternative to CY and ATG.

Isolation and characterization of the human gene homologous to the Drosophila headcase (hdc) gene in chromosome bands 6q23-q24, a region of common deletion in human pancreatic cancer

Deletions of the long arm of chromosome 6 (6q) are one of the most common chromosomal abnormalities in multiple human malignancies. Previously, we have identified three commonly deleted regions on 6q (6q21, 6q23-q24, and 6q26) in pancreatic cancer by loss of heterozygosity studies, suggesting the presence of one or more tumor suppressor genes on this chromosome arm. Using a combination of database search and cDNA library screening, we successfully isolated a transcript from 6q24. This mRNA encodes a protein consisting of 543 amino acids with homology to the Drosophila headcase (hdc) gene and, thus, is designated as hHDC. Northern analysis identified a ubiquitously expressed 5.6-kb transcript. Seventeen (81%) of 21 pancreatic cancer cell lines and four (80%) of five renal cell carcinoma cell lines showed low level expression, suggesting that the hHDC gene may play an important role in some human cancers.

Anomalous pancreaticobiliary junction demonstrated by extraductal ultrasonography using transduodenoscopic miniprobe

We present a case of an anomalous pancreaticobiliary junction (a long common channel) that was clearly demonstrated by extraductal ultrasonography with a transduodenoscopic miniprobe placed in the duodenal lumen. The present case suggests a potential indication for the ultrasound miniprobe, in extraductal ultrasonography, in the pancreatobiliary region. In this method, the position of a miniprobe can readily be adjusted under endoscopic guidance, unlike ordinary endoscopic ultrasonography.

Absence of exacerbation of myocardial stunning in anesthetized dogs treated with KAD-1229, a novel hypoglycemic agent

The effect of (+)-momocalcium bis[(2S,3a,7a-cis)-alpha-benzylhexahydro-gamma-oxo-2-isoindolinebutyrate]dihydrate (KAD-1229), a novel hypoglycemic agent with a chemical structure different from that of the sulfonylureas, on myocardial stunning was assessed in anesthetized dogs by comparison with that of glibenclamide, a sulfonylurea. Even though their hypoglycemic effects were of similar magnitude, glibenclamide (1 mg/kg, i.v.), but not KAD-1229, exacerbated the myocardial stunning induced by occlusion/reperfusion of the descending coronary artery. In a receptor-binding experiment, unlabeled glibenclamide completely inhibited [(3)H]glibenclamide binding to the myocardium, but KAD-1229 did not. These results suggest that the difference in binding properties of KAD-1229 and glibenclamide toward cardiac sulfonylurea receptors is one of the causes of their different effects on myocardial stunning. It is likely that KAD-1229 is highly specific for pancreatic sulfonylurea receptors and is speculated to be a safer hypoglycemic agent than, at least, glibenclamide.

Endoscopic biliary stenting for treatment of bile leakage after hepatic resection

BACKGROUND/AIMS

Persistent bile leakage after hepatic resection may cause intraperitoneal sepsis and hepatic failure. Surgical treatment for bile leakage carries a high risk. Endoscopic treatment has only infrequently been documented.

METHODOLOGY

Ten patients underwent endoscopic biliary stenting without sphincterotomy for persistent (9-138 days; median, 19 days) bile leakage after hepatic resection. Bile leakage was complicated by intraperitoneal sepsis in seven patients.

RESULTS

ERCP showed bile leakage from the bile duct stump in nine patients. Stent placement was successful without complications in all 10 patients. Bile leakage disappeared within 1-17 days (mean, 5 days) in all patients. After 55-91 days, the stent was removed and ERCP confirmed disappearance of the leak. No patients have developed recurrent bile leakage for a mean of 4.1 years of follow-up after stent removal.

CONCLUSIONS

Endoscopic biliary stenting is a safe and effective treatment for persistent bile leakage after hepatic resection. Endoscopic treatment may eliminate the need for difficult operations in high risk postoperative cases.

Preoperative endoscopic pancreatic stenting for safe local pancreatic resection

Local pancreatic resection and enucleation have the advantage of preserving pancreatic parenchyma but pancreatic fistula often occurs postoperatively. We describe a case in which preoperative endoscopic pancreatic stenting prevented pancreatic fistula formation following local pancreatic resection. A pancreatic stent seems to prevent leakage from small pancreatic branch ducts not identified or ligated intraoperatively, via the pancreatic decompression effect. The present case demonstrates a novel indication for endoscopic pancreatic stenting.

Optimal starting time for flutamide to prevent disease flare in prostate cancer patients treated with a gonadotropin-releasing hormone agonist

OBJECTIVE

Flare-up phenomena, such as an increase in prostate-specific antigen (PSA) and/or deterioration of symptoms, are observed in some patients undergoing gonadotropin-releasing hormone (GnRH) agonist therapy. This study was carried out to determine the optimal time for starting the administration of flutamide to prevent flare-up phenomena.

PATIENTS AND METHODS

Twenty-six patients with prostate cancer and elevated serum levels of PSA were randomly assigned to 5 groups. Group A patients (n = 6) were treated with a subcutaneous injection of 3.75 mg leuprorelin acetate depot alone. Group B, C, D and E patients (5 patients in each group) were treated with 375 mg/day of orally administered flutamide combined with leuprorelin. Flutamide was initiated on the day of leuprorelin injection in group B, and at 1, 2 and 4 weeks before leuprorelin injection in groups C, D and E, respectively. Serum PSA and testosterone levels were measured in each patient.

RESULTS

Pretreatment with flutamide increased the serum testosterone level, but the testosterone surge after leuprorelin administration was almost the same in all 5 treatment groups. In patients who had been treated with flutamide in combination with leuprorelin, the mean PSA level did not exceed the pretreatment levels after leuprorelin administration. The rate of decrease in PSA in the group receiving simultaneous administration of flutamide with leuprorelin showed a decline comparable to that during the period before leuprorelin administration in the flutamide pretreatment groups.

CONCLUSION

Simultaneous administration of flutamide with a GnRH agonist is sufficient to prevent flare-up phenomena.

Endoscopic treatment of hemorrhagic gastric ulcer in patients aged 80 years or more

BACKGROUND/AIMS

Hemorrhagic gastric ulcer is a more serious disorder in elderly patients than in young patients. This study aimed to evaluate the efficacy of endoscopic treatment for hemorrhagic gastric ulcer in patients aged 80 years or more.

METHODOLOGY

A total of 269 patients underwent endoscopic treatment for hemorrhagic gastric ulcer with hemoclipping and pure ethanol injection, either alone or in combination. These patients were divided into two groups: elderly (> or = 80 years old) and younger (< 80 years) groups. The clinical data, endoscopic findings and outcomes of endoscopic treatment were compared between these two groups.

RESULTS

Patients in the elderly group had a significantly higher incidence of concomitant disease (73% vs. 23%), anemia (7.9 +/- 2.1 g/dL vs. 9.3 +/- 2.8 g/dL) and large ulcer (23% vs. 6%) compared with the younger group. However, all patients in the elderly group underwent endoscopic hemostasis successfully with no complications and no deaths. The rebleeding rate was not significantly different (8% vs. 4%) between the two groups.

CONCLUSIONS

Elderly patients with hemorrhagic gastric ulcer have high incidences of severe ulcer disease and concomitant medical problems. Endoscopic hemostasis for hemorrhagic gastric ulcer is effective and safe, even for such elderly patients.

Treatment of androgen-independent prostate cancer with dexamethasone: a prospective study in stage D2 patients

PURPOSE

In order to evaluate the efficacy of dexamethasone in the treatment of Japanese men with androgen-independent prostate cancer, a prospective study was conducted using prostate-specific antigen (PSA) as a primary end-point.

METHODS

Nineteen Japanese men with stage D2 androgen-independent prostate cancer were registered and treatment was started. After ruling out anti-androgen withdrawal syndrome, they were treated with dexamethasone (1.5 mg daily). Patients were monitored for PSA, symptoms, radiologic response, survival rate, time to disease progression, time to treatment failure and complications.

RESULTS

Prostate-specific antigen levels decreased in nine patients (50.0%); five (27.8%) showed a 50% or greater decrease and two (11.1%) showed an 80% or greater decrease. For the nine patients, the mean duration of PSA response was 7.3 months and the median duration was 2.1 months (range, 1.2-27.5+). Bone pain, which was noted in 13 patients at study entry, improved in seven patients (53.8%). Of nine patients who had serial radiographic examinations with bone scan, three (33%) showed partial response, two (22%) were stable and four (44%) showed disease progression. Treatment was well tolerated, except for one patient who suffered a severe pulmonary infection.

CONCLUSION

Dexamethasone decreased PSA levels and produced subjective symptomatic improvement in the patients with stage D2 androgen-independent prostate cancer.

Peroral jejunoscopy for treating stenosis of hepaticojejunostomy after pancreatoduodenectomy

A 72-year-old woman suffered from relapsing cholangitis after pylorus-preserving pancreatoduodenectomy for chronic pancreatitis. The common hepatic duct had been anastomosed to the jejunum 8 cm distal to the duodenojejunostomy. Peroral jejunoscopy showed a severe stenosis of the hepaticojejunostomy, which was endoscopically enlarged by means of electroincision and balloon dilation, subsequently. No procedure-related complications occurred. The patient has been asymptomatic for 34 months. Most of the strictures of bilioenterostomy are reportedly treated by surgical revision, the percutaneous transhepatic approach, or the percutaneous transjejunal approach. Endoscopic treatment may be attempted in cases in which the postoperative anatomy potentially allows endoscopic access, because of its minimal invasiveness and effectiveness.

[Phase I study of amrubicin hydrochroride (SM-5887) for superficial bladder cancer in intravesical chemotherapy]

A phase I study of intravesical chemotherapy with amrubicin hydrochloride for superficial bladder cancer was conducted. Amrubicin was dissolved in 30 ml of physiological saline and injected intravesically on 6 consecutive days. The drug solution was retained for 2 hours. The starting dose was 60 mg/day, and the dose was escalated to 150 mg/day in 30 mg/day increments. Fifteen patients were entered into this study, of whom 14 were eligible and assessable for toxicity, and 13 were assessable for efficacy. The incidence and severity of cystic irritabilities such as micturition pain, pollakisuria and hematuria were related to the doses of amrubicin. At 150 mg/day, one of three patients experienced grade 3 micturition pain and pollakisuria. The dose-limiting toxicities, therefore, were micturition pain and pollakisuria, and the maximal tolerated dose was estimated to be 150 mg/day, considering that none of the three patients could retain the drug solution for 2 hours. One complete response and four partial responses were obtained in 13 assessable patients, and the overall response rate was 38.5%. A breakdown according to the doses was as follows. One PR of 3 patients were achieved at 60 and 90 mg/day, respectively 2 PRs of 5 patients at 120 mg/day, and one CR of 2 patients at 150 mg/day.

[Early phase II study of amrubicin (SM-5887) for superficial bladder cancer: a dose-finding study for intravesical chemotherapy]

An early phase II study (dose-finding study) of amrubicin hydrochloride for superficial bladder cancer was conducted. Amrubicin was dissolved in 30 ml of physiological saline and injected intravesically for 6 consecutive days. The drug solution was retained for 2 hours. Patients were randomly assigned to four groups, which were administered amrubicin at doses of 30, 60, 90, and 120 mg/day, respectively. Of 65 patients registered in this study, 63 were eligible and assessable for toxicities, and 55 assessable for efficacy. The response rate at each dose level was 50.0% (7PRs/14 patients) at 30 mg/day, 53.3% (8 PRs/15) at 60 mg/day, 61.5% (2 CRs + 6 PRs/13) at 90 mg/day, and 69.2% (2 CRs + 7 PRs/13) at 120 mg/day, respectively. These data suggests that the efficacy was related to the doses of amrubicin. The major toxicities were cystic irritabilities, such as micturition pain, pollakisuria and hematuria. These toxicities were related to the doses of amrubicin. Their incidence and the severity were not high compared with those reported about other anthracyclines such as doxorubicin and epirubicin. The optimal dose of amrubicin was estimated to be 90 to 120 mg/day in the intravesical treatment for superficial bladder cancer once a day for 6 consecutive days.

Endoscopic hemoclipping for upper GI bleeding due to Mallory-Weiss syndrome

BACKGROUND

Endoscopic hemoclipping is known to be highly effective as hemostatic treatment for upper gastrointestinal bleeding. However, the efficacy and safety of hemoclipping for Mallory-Weiss syndrome (MWS) have not been reported. Thus, the aim of the present study was to assess prospectively the usefulness of endoscopic hemoclipping for MWS bleeding.

METHODS

This study was conducted from January 1994 to August 1999. Hemoclipping was performed when active bleeding (spurting, streaming or oozing), visible vessels or fresh adhesive clots were found on endoscopic examination. Patients who did not have any of these findings were conservatively treated. Follow-up endoscopy was performed within 24 hours, after 5 days and between 1 and 2 months after the procedure.

RESULTS

MWS was diagnosed in a total of 58 patients during the study. Hemoclipping was performed in 26 patients and was technically successful in all cases. The average number of hemoclips used was 2.8 +/- 1.6 (range 1 to 8). The number of hemoclips required for hemostasis depended on the nature of the bleeding. No complications, recurrent bleeding, or deaths resulted. Follow-up endoscopy showed no evidence of hemoclip-induced tissue injury and no impairment of Mallory-Weiss tears.

CONCLUSION

Endoscopic hemoclipping provided an effective and safe modality for obtaining hemostasis when bleeding is due to MWS.

A case of probable acute interstitial pneumonia with a dramatic response to pulse corticosteroid administration

A 38-year-old Japanese male without any significant respiratory risk factors was admitted to our hospital because of an acute onset of fulminant pneumonia refractory to intravenous antibiotics administration and an unexplained creatine kinase elevation. He was intubated and under ventilator support on the second hospital day, but responded dramatically to i.v. pulse methylprednisone treatment. After exclusion of secondary etiologies including collagen diseases, we concluded this case as a probable acute (idiopathic) interstitial pneumonia, or Hamman-Rich syndrome, responding dramatically to the corticosteroid pulse administration.

Characterization of the mutations of the K-ras, p53, p16, and SMAD4 genes in 15 human pancreatic cancer cell lines

Human pancreatic cancer is one of the most malignant diseases in the world. In order to save patients with pancreatic cancer, it is necessary to develop novel methods for treatment. For such a purpose, a series of well-characterized cancer cell lines are of great help for in vitro studies that are generally the first step in approaching the invention of novel methods for treatment. In the present study, we analyzed 15 human pancreatic cancer cell lines for genetic alterations of the K-ras, p53, p16, and SMAD4 genes, which are very frequent targets for mutation in pancreatic cancer; these cell lines are useful resources in cancer research.

Postrest contraction in the ventricular papillary muscle of spontaneously diabetic WBN/Kob rat

In the present study, we investigated the characteristics of the postrest contraction (PRC) in chronic diabetic ventricular muscle. We used WBN/Kob rats of 7-8 weeks as the spontaneously diabetic animal and Wistar rats of 7-8 weeks as the control. We found: (1) No significant differences were seen in the amplitude, the contracting speed, and the relaxing speed of electrically stimulated twitch tension between control and WBN/Kob rats. In addition, the relationship between amplitude of twitch tension and stimulus cycle lengths (0.2-5 sec) was very similar in both animals. (2) The ratios of the first twitch tension (T1) of PRC with various rest intervals (5-600 sec) to the steady-state tension (Tss) were significantly smaller in the diabetic rats than in the controls. (3) When the preparation was stimulated at shorter cycle lengths, the recovery process of PRC was separated into at least two components (fast and slow components). In the diabetic rats, the time constant (tau) of both components was significantly longer than in controls. (4) After caffeine (10(-3) M) treatment, tau of the fast component in the control rats became longer, whereas it remained unchanged in diabetic rats. These findings suggest a dysfunction of the intracellular calcium handling system in spontaneously diabetic heart that is likely to include impaired calcium sequestration and/or extrusion.

Isolation and characterization of the novel gene, TU3A, in a commonly deleted region on 3p14.3-->p14.2 in renal cell carcinoma

We previously identified a 700-kb region of common allelic loss on 3p14.3-->p14.2 in renal cell carcinoma (RCC). We further analyzed this region and constructed a sequence ready bacterial artificial chromosome (BAC) contig. This region was totally covered by six overlapping BAC clones and was roughly estimated to be 700 kb. Furthermore, we isolated a gene in this region that we termed TU3A. This gene encodes a protein consisting of 144 amino acids. Homology search did not show any significant similarities with known genes or proteins. Northern analysis with normal tissue identified a 3.0-kb transcript that was expressed ubiquitously. Although our mutation search using 37 primary RCCs as well as five RCC cell lines failed to detect any somatic alterations in the TU3A gene, two of five RCC cell lines had totally lost its expression. Considering the fact that we found no genetic alterations in TU3A, it is possible that some epigenetic alteration may have suppressed its expression.

Endoscopic ultrasonography for differential diagnosis of polypoid gall bladder lesions: analysis in surgical and follow up series

BACKGROUND

Differential diagnosis is often difficult for small (</=20 mm) polypoid lesions of the gall bladder.

AIM

To assess the diagnostic accuracy of endoscopic ultrasonography (EUS) for polypoid lesions in a surgical and follow up series.

METHODS

A total of 194 patients with small polypoid lesions underwent both ultrasonography and EUS. A tiny echogenic spot or an aggregation of echogenic spots and multiple microcysts or a comet tail artefact indicated cholesterol polyp and adenomyomatosis respectively. Other lesions were diagnosed as neoplastic (adenoma or adenocarcinoma). In the 58 patients who underwent surgery, the histological diagnoses were cholesterol polyp (n = 36), adenomyomatosis (n = 7), adenoma (n = 4), and adenocarcinoma (n = 11). Of the remaining 136 patients with an EUS diagnosis of non-neoplastic lesions, 125 were followed up with ultrasonography alone or with EUS for 1-8.7 years (mean 2.6 years).

RESULTS

In the surgical series, EUS (97%) differentiated polypoid lesions more precisely than ultrasonography (76%). During follow up, the lesions remained unchanged in size in 109 (87%) of the 125 patients with non-neoplastic lesions diagnosed by EUS. No neoplastic lesions developed in these patients. Ultrasonography had shown lesions to be neoplastic in 13% of the follow up series.

CONCLUSIONS

EUS is highly accurate for differentially diagnosing polypoid gall bladder lesions. It is recommended when ultrasonography cannot rule out neoplastic lesions. Non-neoplastic lesions diagnosed by EUS may be followed and observed with ultrasonography.

Electrophysiological properties of ventricular muscle obtained from spontaneously diabetic mice

The electrophysiological properties of cardiac muscle in KK/Ta mouse (hereafter referred to as KK mouse), an animal model of human non-insulin-dependent diabetes mellitus, were investigated, and the findings compared with those obtained from a non-diabetic control mouse (C57BL/6J mouse; referred to as B6 mouse). The ages of the B6 mice were 23.9 +/- 5.4 weeks (n = 24) and those of the KK mice used were 25.7 +/- 10.8 weeks (n = 34). The KK mice had mild obesity, hyperglycemia and hyperinsulinemia. Ventricular muscles from both mice were examined by light microscopy. Partial myocardial fibrosis and filament disorder in the ventricular muscles were found only in the KK mice. The resting membrane potential of the ventricular muscle was less negative in the KK mice than in the control mice. The maximum rate of rise in the upstroke of the action potential was significantly decreased in the KK mice compared with that of the control mice. These suggest a decrease in a time-independent K+ current (IK1) in the KK mice. The duration of the action potential (APD) at all levels of repolarization was significantly longer in the KK mice than in the B6 mice. A blocker of transient outward current (I(to)), 4-aminopyridine, significantly prolonged the APD of the B6 mice, but failed to prolong it in the KK mice, suggesting that Ito in the diabetic mice is very small. A Ca2+ channel blocker, CoCl2, dramatically lengthened all levels of APD in both groups, suggesting that there is no difference between B6 mice and KK mice in L-type Ca2+ current via Ca2+ channels. These suggest the malfunction or deficiency of ionic channels which carry, at least Ito and IK1 in diabetic mice.

Frequent expression of mucin core protein MUC1 in non-neoplastic gallbladder mucosa from patients with pancreaticobiliary maljunction

BACKGROUND

Gallbladder carcinoma is known to develop frequently in patients with pancreaticobiliary maljunction, though the causal relationship remains speculative.

METHODS

Histopathologic changes, expression of mucin core protein MUC1 and MUC2, and cell proliferative activities in the gallbladder mucosa from 27 patients with panceaticobiliary maljunction and 21 control gallbladders were examined. Three cases of pancreaticobiliary maljunction were associated with gallbladder carcinoma.

RESULTS

The lining epithelia of the non-neoplastic gallbladder mucosa of pancreaticobiliary maljunction showed frequently papillary hyperplasia and higher proliferative activities, when compared to the control. In 3 cases with carcinoma, MUC1 was expressed on the luminal border and in the cytoplasm of carcinoma cells, particularly in de-differentiated and invasive areas. MUC1 was variably expressed on the luminal surface of the lining epithelia of non-neoplastic gallbladder mucosa in babies, children, youths and adults with pancreaticobiliary maljunction. However, such expression was focally seen in 2 of the 21 control cases (p<0.01). MUC2 was scattered in the hyperplastic and carcinomatous epithelial cells appearing as goblet cells in pancreaticobiliary maljunction and control groups.

CONCLUSIONS

This study suggests that persistent MUC1 expression and increased cell proliferative activities of non-neoplastic gallbladder epithelium of the patients with pancreaticobiliary maljunction after birth reflect an altered phenotype of epithelial cells and these abnormalities may be related to carcinogenesis in such patients.

Expression of MUC1 and MUC2 mucin core proteins and their messenger RNA in gall bladder carcinoma: an immunohistochemical and in situ hybridization study

Expression of mucin core protein MUC1 and MUC2 was examined at the protein and mRNA level in 55 cases of carcinoma and 20 of dysplasia, and in 15 non-dysplastic epithelia of the gall bladder. In non-dysplastic epithelium, MUC1 protein was not expressed, while in dysplasia, MUC1 was focally expressed in ten cases, particularly in those associated with carcinoma. In carcinoma, MUC1 was expressed heterogeneously, and the frequency and extent of MUC1 expression increased with histological dedifferentiation. MUC1 was found on the apical cell surface and also in the cytoplasm in well- and moderately-differentiated carcinoma, and on the cell border in poorly-differentiated cases. In infiltrative regions, MUC1 expression was more predominant and MUC1 frequently leaked outside the foci of carcinoma. By contrast, MUC2 was focally expressed in non-dysplastic as well as in dysplastic epithelia and more frequently in well-differentiated adenocarcinoma. MUC2-positive cells resembled goblet cells, whether in non-dysplastic epithelium, dysplasia or carcinoma. Cell proliferative activity was higher in MUC1-positive than in MUC1-negative carcinoma cells. Distributions of MUC1 and MUC2 mRNA signals and of MUC1 and MUC2 proteins were similar in carcinoma and dysplasia. These results suggest that MUC1 expression by gall bladder carcinoma may reflect histological dedifferentiation, increased proliferative activity, and invasiveness, while MUC2 expression is related to lower proliferative activity and reflects some differentiation towards goblet cells; and that MUC1 expression in gall bladder dysplasia reflects malignant transformation.

Expression of sialyl-Tn, Tn and T antigens in primary liver cancer

Sialyl-Tn, Tn and T antigens are caused by aberrant or incomplete glycosylation of apomucins and are related to the aggressiveness of malignant neoplasms. Using 41 liver samples from patients with cholangiocarcinoma (including four with cirrhosis), 21 with combined hepatocellular-cholangiocellular carcinoma and 17 with hepatocellular carcinoma, the expression of sialyl-Tn, Tn and T antigens were characterized immunohistochemically and the correlation with apomucin profiles was evaluated. The prevalence of sialyl-Tn, Tn and T antigens expression was 89, 95 and 51% in cholangiocarcinoma without cirrhosis; 25, 75, and 0% in cholangiocarcinoma with cirrhosis; 29, 90, and 48% in combined hepatocellular-cholangiocellular carcinoma; and 0, 12 and 6% in hepatocellular carcinoma, respectively. Sialyl-Tn antigen was frequently expressed in cholangiocarcinoma without cirrhosis compared with cholangiocarcinoma with cirrhosis and combined hepatocellular-cholangiocellular carcinoma (P < 0.01). Although sialyl-Tn expression was associated with MUC1, MUC6 and MUC7 expression, the expression sites among them were not identical in the individual cases. These data suggest that the different expressions of sialyl-Tn antigen among cholangiocarcinoma without cirrhosis, cholangiocarcinoma with cirrhosis and combined hepatocellular-cholangiocellular carcinoma may reflect the biological features inherent to these tumors, such as the ability of invasion.

Expression of MUC2, MUC5AC and MUC6 apomucins in carcinoma, dysplasia and non-dysplastic epithelia of the gallbladder

To date, nine apomucins have been characterized and their expression in malignant and premalignant lesions is under evaluation. The purpose of this study was to characterize immunohistochemically the expression of MUC2 (colonic/ intestinal type), MUC5AC (gastric surface type), and MUC6 (pyloric gland type) apomucins in 55 patients with gallbladder carcinoma (10 with in situ carcinoma, 45 with invasive carcinoma), 20 patients with gallbladder dysplasia, and 15 patients with non-dysplastic gallbladder. MUC2 was expressed mainly in 'goblet type' cells. The frequency was increased in non-dysplastic gallbladder (47%), dysplasia (75%), and in situ carcinoma (100%), and decreased in invasive carcinoma (58%). Carcinoma cells expressing MUC2, which were usually distributed at superficial areas, and well-differentiated carcinoma expressed MUC2 more extensively than moderately and poorly differentiated ones. MUC5AC was frequently expressed in gallbladder irrespective of non-dysplastic epithelia, dysplasia and carcinoma. MUC5AC was expressed also in carcinoma cells at deeply invasive sites. MUC6 was expressed frequently in pseudopyloric gland metaplasia as well as dysplasia and carcinoma. In conclusion, non-dysplastic gallbladder has a similar phenotype to gastric pyloric mucosa. Gallbladder carcinoma exhibits both intestinal and gastric surface phenotypes in the early stage of carcinogenesis, with the gastric surface phenotype dominant in invasive carcinoma.

Antiarrhythmic effects of magnesium on rat papillary muscle and guinea pig ventricular myocytes

1. Despite widespread use of magnesium ion (Mg2+) for antiarrhythmic purposes, little direct information is available regarding its antiarrhythmic mechanisms. To elucidate the possible cellular mechanism, the effects of Mg2+ on early afterdepolarization (EAD), delayed afterdepolarization (DAD), triggered activity (TA), transient inward current (TI) and aftercontraction (AC) were examined in various cardiac preparations. The effects of Mg2+ on myoplasmic Ca2+ concentration were also studied. 2. The effects of Mg2+ on AC, induced by overdrive stimulation, were studied in isolated rat ventricular papillary muscle superfused with low K+ solution. In enzymatically isolated guinea pig myocytes, EAD, DAD and/or TA were induced after overdrive stimulation under conditions of superfusion with low K+ solution, using the whole-cell current-clamp method, and TI was also induced by the whole-cell voltage-clamp method. 3. Immediately after changing the solutions, containing varying concentrations of Mg2+, the effects of Mg2+ were examined. In addition, effects of Mg2+ on Ca transient were studied, using fura-2. 4. We found that: (1) in the rat papillary muscle, 10 mM Mg2+ effectively inhibited AC, which was produced after stimulation at both 3.3 Hz and 5 Hz, although 5 mM Mg2+ was without effect in the case of AC induced after 5-Hz stimulation; (2) in the myocytes, 5 mM Mg2+ did not inhibit DADs, EADs and TA, but 10 mM Mg2+ inhibited them completely; (3) the amplitude and frequency of TI decreased significantly in the presence of 10 mM Mg2+; and finally (4) 10 mM Mg2+ inhibited the Ca transient underlying DAD and/or TA. 5. The findings suggest, but do not prove unequivocally, that Mg's actions are probably due to a combination of a shift of the threshold of various ion channels to less negative potentials, a decrease in Ca2+ influx via Ca channels, a block of several K channels, and/or a block of Na-Ca exchanger. In conclusion, the present study indicates that extracellular Mg2+, via whatever mechanism, exerts antiarrhythmic activities.

Novel method to detect a motif of local structures in different protein conformations

In order to detect a motif of local structures in different protein conformations, the Delaunay tessellation is applied to protein structures represented by C(alpha) atoms only. By the Delaunay tessellation the interior space of the protein is uniquely divided up into Delaunay tetrahedra whose vertices are the C(alpha) atom positions. Some edges of the tetrahedra are virtual bonds connecting adjacent residues' C(alpha) atoms along the polypeptide chain and others indicate interactions between residues nearest neighbouring in space. The rules are proposed to assign a code, i.e., a string of digits, to each tetrahedron to characterize the local structure constructed by the vertex residues of one relevant tetrahedron and four surrounding it. Many sets comprised of the local structures with the same code are obtained from 293 proteins, each of which has relatively low sequence similarity with the others. The local structures in each set are similar enough to each other to represent a motif. Some of them are parts of secondary or supersecondary structures, and others are irregular, but definite structures. The method proposed here can find motifs of local structures in the Protein Data Bank much more easily and rapidly than other conventional methods, because they are represented by codes. The motifs detected in this method can provide more detailed information about specific interactions between residues in the local structures, because the edges of the Delaunay tetrahedra are regarded to express interactions between residues nearest neighbouring in space.

Molecular dynamics study of femtosecond events in photoactive yellow protein after photoexcitation of the chromophore

Molecular dynamics simulations were carried out to study what happens in a photoreceptor protein, photoactive yellow protein (PYP), immediately after the vertical transition of the chromophore from the ground to the excited state. A photon absorption simulation was performed to investigate the movement of amino acid residues upon photoexcitation. To calculate the excited state of the chromophore, SCF-CI calculation was carried out with INDO/S Hamiltonian. We observed that some amino acid residues have strong interactions with the chromophore. Most of these amino acid residues are conserved in PYPs from three different species of bacteria. This observation indicates the biological importance of these residues.

Inhibitory effects of lipid oxidation on the activity of plasma lecithin-cholesterol acyltransferase

We investigated the effects of free radical generation on the esterification of cholesterol by lecithin-cholesterol acyltransferase (LCAT). A water-soluble free radical initiator, 2,2'-azobis-amidinopropane dihydrochloride (AAPH), inhibited the activity of plasma LCAT as a function of the incubation time after its addition. When a small amount of oxidized HDL was added to plasma, LCAT activity was dose-dependently inhibited. To identify the effects of HDL oxidation on LCAT activity, a purified enzyme and cofactor in a vesicle solution (an artificial substrate) were used. i) LCAT activity was inhibited by the oxidation of substrate vesicles, this inhibition being related to the degree of oxidation. ii) This inhibition was observed even if apolipoprotein A-I was not oxidized. iii) Oxidized phosphatidylcholine, but not oxidized cholesterol, in the vesicles affected LCAT activity. iv) The addition of 0-40% of oxidized vesicles to normal substrate vesicles resulted in the activity of LCAT being inhibited in a dose-dependent manner. These results suggest that the esterification of cholesterol by LCAT may be affected by the oxidation of substrate phosphatidylcholine via free radical generation in the plasma.

Intrahepatic cholangiocarcinoma arising in congenital hepatic fibrosis: report of an autopsy case

We report an autopsy case of a 60-year-old woman who had congenital hepatic fibrosis with intrahepatic cholangiocarcinoma. A white nodular lesion with a surrounding vague gray area was detected in the right lobe of the liver. Microscopically, most of the nodular lesion was a poorly-differentiated adenocarcinoma. In the surrounding gray area, small bile ducts and bile ductules showed prominent epithelial overgrowth, some of which was composed of dysplasia and well-differentiated adenocarcinoma. The background liver showed the characteristic features of congenital hepatic fibrosis. Immunohistochemically, biliary oncofetal markers (mucin core protein 1 and carcinoembryonic antigen) were more frequently and extensively expressed in poorly-differentiated than well-differentiated adenocarcinoma. This is the 4th reported case of intrahepatic cholangiocarcinoma arising in congenital hepatic fibrosis and suggests that malignant transformation via dysplasia occurs in the abnormal intrahepatic biliary tree of older congenital hepatic fibrosis patients.

Mechanical property of a TIM-barrel protein

The mechanical response of a TIM-barrel protein to an applied pressure has been studied. We generated structures under an applied pressure by assuming the volume change to be a linear function of normal mode variables. By Delaunay tessellation, the space occupied by protein atoms is divided uniquely into tetrahedra, whose four vertices correspond to atomic positions. Based on the atoms that define them, the resulting Delaunay tetrahedra are classified as belonging to various secondary structures in the protein. The compressibility of various regions identified with respect to secondary structural elements in this protein is obtained from volume changes of respective regions in two structures with and without an applied pressure. We found that the beta barrel region located at the core of the protein is quite soft. The interior of the beta barrel, occupied by side chains of beta strands, is the softest. The helix, strand, and loop segments themselves are extremely rigid, while the regions existing between these secondary structural elements are soft. These results suggest that the regions between secondary structural elements play an important role in protein dynamics. Another aspect of tetrahedra, referred to as bond distance, is introduced to account for rigidities of the tetrahedra. Bond distance is a measure of separation of the atoms of a tetrahedron in terms of number of bonds along the polypeptide chain or side chains. Tetrahedra with longer bond distances are found to be softer on average. From this behavior, we derive a simple empirical equation, which well describes the compressibilities of various regions.

Strain tensor field in proteins

The tensor fields of pressure strain imposed on protein molecules have been visualized by computer graphics and computational geometry. The pressure-induced deformations of lysozyme and myoglobin were analyzed by the present method, which regards each molecule as a patchwork of microscopic continuous bodies of Delaunay tetrahedra. The strain tensor describes the deformation of each tetrahedron. The illustrated deformations turned out to be complex and inhomogeneous ones in which local expansions and contractions concomitantly occurred. Not only the pressure deformation but also any other type of moderate deformation can be analyzed by this method.

Capsaicin does not inhibit the intracellular calcium handling process in rat ventricular papillary muscle

1. We studied the effects of capsaicin, a pungent agent extracted from red pepper, on rested-state contraction (RSC) of isolated rat ventricular papillary muscles. 2. The RSC was induced by stimulation, after a rest interval of 5 sec to 10 min, after the twitch tension of the muscle preparation stimulated at the regular stimulus frequency of cycle lengths of 5, 1 or 0.2 sec attained the steady state. 3. Drug effects were evaluated on the RSC in the presence of capsaicin 10(-5) M, caffeine 10(-2) M or ryanodine 10(-7) M, respectively. 4. All drugs inhibited the RSC but to different degrees. Ryanodine was the most effective in inhibiting RSC, followed by caffeine and capsaicin, in that order. However, the inhibitory mode varied, depending on the drugs. 5. These findings suggest that capsaicin may not inhibit the function of intracellular Ca2+ store in rat cardiac muscle.

Inhibition of contractile tension by capsaicin in isolated rat papillary muscle

1. We examined effects of capsaicin (10(-9) - 10(-5) M), a pungent agent extracted from red pepper, on the contractile tension of rat ventricular papillary muscles stimulated at various cycle lengths (0.2, 0.5, 1, 2 and 5 sec). 2. Capsaicin produced a marked concentration-dependent decrease in the amplitude, the rate of rise (dp/dt) and the rate of relaxation (dr/dt) of the tension. 3. However, the half relaxation time and the time to peak tension of the tension were slightly affected by the agent. 4. The negative inotropic effect of capsaicin was stimulus cycle length (CL) dependent. In particular, IC50 (50% inhibitive concentration) of the agent in the amplitude of the tension was stimulus CL dependent. That is, the values of IC50 were around 10(-7) M at longer CLs (1, 2 and 5 sec), and the value of IC50 at CL 0.2 sec was 4 x 10(-6) M. 5. These capsaicin-induced negative inotropic effects were reversible. Other studies from our laboratory show that the negative inotropic effects may be largely due to a decrease in Ca2+ current.