Yasuyuki Karasawa

Extracorporeal shock wave lithotripsy of pancreatic duct stones and patient factors related to stone disintegration

Background:Background: Stones in the main pancreatic duct (MPD) are difficult to remove by endoscopic devices alone in some patients who have chronic pancreatitis. We treated these patients with extracorporeal shock wave lithotripsy (ESWL) and analyzed the patient factors related to disintegration. Methods: Twenty-four patients were treated with ESWL alone or with combined endoscopic-ESWL to disintegrate or remove MPD stones. Results: Ten patients were treated by ESWL alone and 14 by combined endoscopic-ESWL. A total of 19 patients (79%) were effectively treated by either method. The mean MPD diameter decreased significantly after ESWL. In most of the patients who had chronic abdominal symptoms, these symptoms were relieved at discharge. Severe side effects of complications did not occur during ESWL therapy. Acute abdominal symptoms and a significant increase in the white blood cell count, total bilirubin, and aspartate aminotransferase were observed only immediately after ESWL. Although there were no significant differences, we observed that the patients with a higher stone disintegration success rate showed the following factors: (1) female, (2) non-alcoholic pancreatitis, (3) younger age, (4) shorter duration of symptoms, (5) smaller stones, and (6) a lower Hounsfield unit value of stones. Although about half of the patients had recurring abdominal symptoms and stones during a follow-up period of 12 months, the stones which caused relapse in short-term intervals were disintegrated easily by ESWL. Conclusions: We may consider the application of ESWL therapies for patients who show the factors associated with easily disintegratable stone conditions. These therapies are highly effective and relatively safe procedures for pancreatic duct stones in such patients.

Inhibition by glibenclamide of negative chronotropic and inotropic responses to pinacidil, acetylcholine, and adenosine in the isolated dog heart

The blocking effects of glibenclamide on the chronotropic and inotropic responses to K+ channel openers pinacidil (ATP-sensitive) and acetylcholine (ACh) or adenosine (receptor-operated) were investigated in the isolated, blood-perfused canine atrium or ventricle. Glibenclamide (0.1–3 μmol) induced no significant cardiac effects. Cumulative administration of pinacidil (0.03–3 μmol) dose-dependently decreased sinus rate much less than the contractile force of the atrial and ventricular muscles. Glibenclamide similarly inhibited the negative chronotropic and inotropic responses to pinacidil in a dose-related manner. A high dose of glibenclamide (3 μmol) slightly but significantly attenuated the negative chronotropic and inotropic responses to ACh and adenosine but not to verapamil. These results demonstrate that glibenclamide inhibits the negative chronotropic and inotropic responses to the ATP-sensitive K+ channel opener pinacidil and the receptor-operated K+ channel openers ACh and adenosine but more selectively antagonizes the responses to pinacidil in the dog heart and suggest that in contrast to ACh and adenosine, an ATP-sensitive K+ channel opener has a greater effect on the ventricle than on the sinoatrial node.

Cardiac responses to VIP and VIP-ergic-cholinergic interaction in isolated dog heart preparations

Whereas i.v. administration of vasoactive intestinal peptide (VIP) to support dogs increased heart rate and decreased systemic blood pressure, sinus rate and contractile force increased in isolated right atria perfused with blood from the support dogs. VIP injected intraarterially into isolated atria induced dose-dependent positive chronotropic and inotropic effects. Intracardiac parasympathetic nerve stimulation attenuated the positive cardiac responses to VIP, but neither propranolol, imipramine, nor tetrodotoxin influenced the responses to VIP. VIP given to isolated left ventricles also increased the contractile force in a dose-dependent manner. However, VIP induced a greater maximum atrial contractility than ventricular contractility. This may indicate that VIP receptor density in the ventricle was lower than in the atrium, as it has recognized that VIP-ergic nerves innervate the right atrium more densely than the left ventricle. We therefore suggest that the positive cardiac responses to VIP, together with the VIP-ergic innervation in dog hearts and vagal activation, attenuate the VIP-mediated responses at site(s) in the cyclic AMP cascade.

Hepatocarcinogenesis inhibition by caffeine in ACI rats treated with 2-acetylaminofluorene

The inhibitory effects of caffeine have been demonstrated on the development of various organs in animals. The purpose of the present study was to examine the inhibitory effect of caffeine on hepatocarcinogenesis and to determine the responsive dose of caffeine on hepatocarcinogenesis in young male ACI rats. Animals given a diet containing 2-acetylaminofluorene (2-AAF) for 12 weeks and then a basal diet and tap water containing caffeine for 18 weeks showed statistically significant decreases in the incidence, multiplicity (the number of hepatic tumors per rat) and histological grade compared with rats fed a diet containing carcinogen for 12 weeks followed by tap water alone. Dose-dependent inhibition of hepatocarcinogenesis by caffeine was also seen. The inhibitory effect of caffeine on hepatocarcinogenesis in rats was found when caffeine was administered during the initiation phase.

Reassessment of K-ras mutations at codon 12 by direct PCR and sequencing from tissue microdissection in human pancreatic adenocarcinomas

K-ras mutations at codon 12 have been detected in almost all pancreatic adenocarcinomas by highly sensitive assays. We reassessed the K-ras mutation status by direct polymerase chain reaction (PCR) and sequencing from tissue microdissection without DNA extraction in 10 pancreatic adenocarcinomas, and also assessed the K-ras and DPC4 genes in nine pancreatic cancer cell lines. Eight pancreatic adenocarcinomas were found to harbor K-ras mutations at codon 12 of either GTT or GAT, five of which were inferred to harbor amplified mutant alleles. Mutations at the sites other than codon 12 were found in seven of 70 clones (seven of 9,380 bases) by the TA cloning analysis, suggesting that artifactual mutations at the first or second base of codon 12 before and during PCR could occur at a frequency of ∼10−3, enough for highly sensitive assays to detect. Two cell lines without K-ras mutations at codon 12 were found to have homozygous deletions at the DPC4 gene. Thus the K-ras mutation status was demonstrated to be correctly determined by just direct sequencing from tissue microdissection. All possible mutations or multiple mutations at K-ras codon 12 that have been reported in pancreatic adenocarcinomas might include artifacts or mutations without a selective advantage. In addition, we must be very cautious about contamination.

A case of glycogen storage disease type Ia with multiple hepatic adenomas and G727T mutation in the glucose-6-phosphatase gene, and a comparison with other mutations previously reported.

We report a case of 23-yr-old man with glycogen storage disease (GSD) type Ia complicated by multiple hepatic adenomas. Analysis of the G-6-Pase gene using peripheral blood sample showed this patient to be homozygous for a G-to-T transversion at nucleotide 727 in exon 5. This mutation is prevalent among Japanese patients, suggesting that specific genotypes may correlate with different clinical courses or outcomes.

Cardiac effects of vecuronium and its interaction with autonomic nervous system in isolated perfused canine hearts.

Summary: The chronotropic and inotropic effects of vecuronium bromide and its interaction with the autonomic nervous system were investigated in the isolated, cross-circulated right atrial and left ventricular preparations of the dog. Vecuronium, injected into the external jugular vein of the support dog, induced dose-dependent decreases in heart rate and arterial blood pressure, and increased atrial contractile force with no change in sinus rate in isolated atrial preparations. Vecuronium (1–3,000 μg), injected into the sinus node artery of the isolated atrium, induced dose-dependent increases in atrial contractile force with small increases in sinus rate. Vecuronium also increased the ventricular contractile force in a dose-dependent manner. The positive inotropic effect was attenuated in part by propranolol, but not by either tetrodotoxin or imipramine. Vecuronium inhibited in a dose-related manner the negative chronotropic and inotropic responses to parasympathetic nerve stimulation and carbachol (CCh) and the negative followed by positive cardiac responses to nicotine, but did not attenuate the positive responses to sympathetic nerve stimulation. The ID50s for the responses to parasympathetic stimulation, CCh, and nicotine were not significantly different. Vecuronium enhanced the positive chronotropic and inotropic responses to sympathetic nerve stimulation, tyramine, norepinephrine, and isoproterenol. These results indicate that (a) vecuronium causes the positive inotropic responses mediated by nonadrenergic mechanisms and β-adrenoceptors, (b) vecuronium blocks ganglionic and presynaptic nicotinic and postsynaptic muscarinic receptor-mediated responses similarly, and (c) vecuronium enhances β-adrenoceptor-mediated responses in the dog heart.

Cardiovascular effects of R- and S-enantiomers of Ro 22-9194, (2R)-2-amino-N-(2,6-dimethylphenyl)-N-[3-(3-pyridyl)propyl]propionamide D-tartrate and (2S)-2-amino-N-(2,6-dimethylphenyl)-N-[3-(3-pyridyl)propyl]propionamide L-tartrate, in dog heart preparations

Summary: A newly synthesized compound, Ro 22–9194, relates in part to the chemical structure of lidocaine. The cardiac effects of R- and 5-enantiomers of Ro 22–9194 were investigated on isolated right atrial and left ventricular (LV) preparations which were cross-perfused with blood from another donor dog and an anesthetized open-chest dog. Each enantiomer (1–1,000 μ,g) decreased dose-dependently the sinus rate and atrial developed tension in the isolated right atrium (RA). The negative chronotropic responses to R- and S-enantiomers were not significantly different, and the negative inotropic responses to R- and S-enantiomers were also generally comparable. Both R- and S-enantiomers (10–3,000 μ,g) also decreased the ventricular developed tension in a dose-related manner similarly. In neurally decentralized, anesthetized, open-chest dogs, R- and S-enantiomers (0.1–3 mg/kg) injected into the femoral vein dose-dependently prolonged atrioventricular (A-V) conduction time and decreased heart rate (HR) and arterial blood pressure (ABP). Each enantiomer (3 mg/kg intravenously, i.v.) prolonged the interval between His bundle and ventricle rather than the interval between atrium and His bundle. There was no significant difference between R- and S-enantiomer-induced negative dromotropic actions. The duration of the negative dromotropic response to each enantiomer (3 mg/kg i.v.) was longer than that of the decrease in BP. These results suggest that the negative chronotropic, inotropic, and dromotropic effects of R- and S-enantiomers of Ro 22–9194 are not stereospecific in dog heart.

Different sympathetic–parasympathetic interactions on sinus rate and AV conduction in dog hearts

We investigated the sympathetic-parasympathetic interactions involved in SA nodal pacemaker activity and AV conductivity in the anesthetized dog heart. Stimulation of the intracardiac parasympathetic nerves to the SA nodal region (SAPS) and stimulation of the intracardiac parasympathetic nerves to the AV nodal region (AVPS) induced negative chronotropic and dromotropic responses, respectively. Cardiac sympathetic stimulation, aminophylline, 3-isobutyl-1-methylxanthine (IBMX, a relatively pure nonselective phosphodiesterase inhibitor) and methyl-1,4-dihydro-2,6-dimethyl-3-nitro-4-(2-trifluoromethylphenyl)-p iridine-5-carboxylate (Bay k 8644, a Ca2+ channel agonist) increased sinus rate and decreased AV conduction time. Sympathetic stimulation augmented the negative chronotropic response to SAPS but not the negative dromotropic response to AVPS, IBMX augmented both responses, Bay k 8644 augmented the chronotropic response and attenuated the dromotropic response, and aminophylline did not affect the chronotropic response to SAPS and inhibited the dromotropic response to AVPS. Additionally, when Bay k 8644 directly given via the AV node artery decreased AV conduction time, it attenuated the negative dromotropic response to AVPS and carbachol injected into the AV node artery. These results suggest that the differential sympathetic-parasympathetic interactions on sinus rate and AV conduction are at least partly induced by an interaction between changes in slow inward Ca2+ current or intracellular Ca2+ and the cardiac effects of acetylcholine in the heart in situ.

Distribution of neurally activated postjunctional adrenoceptors in cat forelimb vasculature.

Summary We assessed the relative contribution of postjunctional α-adrenoceptor subtypes in neurally evoked vasoconstrictor responses in the forelimb of anesthetized cats. Preganglionic stimulation of the thoracic sympathetic nerve trunk produced frequency-related decreases in blood flow of the entire forelimb as measured by ultrasonic flowmetry as well as vasoconstriction in the digital cutaneous bed as measured by laser-Doppler flowmetry. Vasoconstrictor responses were not altered significantly by intravenous (i.v.) treatment with propranolol (1 mg/kg) or atropine (1 mg/kg). In the entire limb, prazosin, (3–100 μg/kg i.v.) was a more potent antagonist of neurally evoked responses as compared with rauwolscine. In contrast, rauwolscine (10–300 μg/kg i.v.) was a more effective antagonist in the cutaneous bed. Combined treatment with both prazosin and rauwolscine was far more effective than either antagonist given alone in blocking vasoconstriction regardless of the measurement site. Moreover, basal cutaneous blood flow was increased by rauwolscine but not by prazosin. These results suggest that both subtypes of postsynaptic α-adrenoceptors are activated by sympathetic nerve stimulation. In the cutaneous bed, α2-adrenoceptors appear to predominate. In addition, cutaneous vascular tone also appears to be regulated by hormonal α2-adrenoceptor activation in cats.