Muscarinic receptor subtypes mediating Ca2+ sensitization of intestinal smooth muscle contraction: studies with receptor knockout mice

In the present study, we have characterized muscarinic receptor subtypes that mediate carbachol-induced Ca2+ sensitization of contraction in intestinal smooth muscle, using mutant mice lacking M(2) or M(3) muscarinic receptors or both receptor subtypes. In alpha-toxin-permeabilized muscle strips from wild-type (WT) mice, isometric tension responses to Ca2+ applied cumulatively (pCa 7.0-5.0) were increased when the muscarinic agonist carbachol (100 microM) was added to the medium, as judged from shifts of pCa-tension curves in both 50% effective concentration (EC(50)) and maximum response (E(max)) of pCa-tension curve. In preparations from M(2)-knockout (KO) mice, pCa-tension curves were also shifted by carbachol (100 microM), and the extents of the EC(50) and E(max) changes resembled those observed in preparations from WT mice. In preparations from M(3)-KO or M(2)/M(3)-double KO mice, however, no significant changes in pCa-tension curves were obtained after carbachol application. The G(q/11)-type G-protein inhibitor YM-254890 (1 microM) completely blocked the Ca2+ sensitization of contraction induced by carbachol in M(2)-KO or WT preparations. The results strongly support the idea that the muscarinic activation of Ca2+ sensitization in intestinal smooth muscles is mediated by the M(3) muscarinic receptor coupled to G(q/11)-type G-proteins, without any significant involvement of the other muscarinic receptor subtypes including M(2).

A non-selective cationic channel activated by diacylglycerol in mouse intestinal myocytes

Application of 1-oleoyl-2-acetyl-sn-glycerol (OAG), an analogue of diacylglycerol (DAG) formed via M(3) muscarinic receptors, induced inward cationic currents via a protein kinase C-independent mechanism and produced membrane depolarization with increased action potential discharges in mouse intestinal myocytes. Outside-out patches from the myocytes responded to OAG with openings of 115-pS channels characterized by a mean open time (O(tau)) of 0.15 ms. M(3) receptor stimulation is reportedly capable of causing brief openings (O(tau)=0.23 ms) of 120-pS cationic channels in intestinal myocytes, thus the present results strongly support the idea that the M(3)-mediated 120-pS channel opening is brought about via DAG-dependent mechanisms.

A phase II study of weekly paclitaxel and doxifluridine (an intermediate metabolite of capecitabine) combination chemotherapy for advanced/recurrent gastric cancer

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Background: Paclitaxel and doxifluridine (5’-DFUR; an intermediate metabolite of capecitabine), which have distinct mechanisms of action and toxicity profiles, each have considerable single-agent activity in gastric cancer. A synergistic interaction between these two drugs was suggested from the taxane-induced upregulation of thymidine phosphorylase, which converts 5’-DFUR to 5-FU. Therefore, this study evaluated the antitumor activity and toxicities of paclitaxel and 5’-DFUR in combination in patients with advanced/recurrent gastric cancer (AGC) Methods: Patients with histologically confirmed AGC, which was unresectable or metastatic, PS 0–2, and over 20 years old were eligible for this study. The treatment included paclitaxel 80 mg/m2 i.v. on days 1, 8, and 15 every 4 weeks and doxifluridine 533 mg/m2 p.o. on days 1–5/week until there was disease progression or the appearance of unacceptable toxicity. Results: Between April 2003 and May 2006,104 patients were enrolled in this study. Their median age was 67.0 years (range: 36–82) and 87 patients were male. Forty-three patients had advanced gastric cancer and 61 had recurrent gastric cancer. After a median of 3 (range: 1- 21) cycles of chemotherapy, 104 patients were evaluated for toxicity and 93 patients were evaluated for response. In the intention-to-treat analysis, the overall response rate was 32.3% (95% C.I., 22.8–41.8%), including 2 CR, 28 PRs, 37 SDs, 16 PDs, and 10 NEs. The first-line therapy involved 48 patients (primary advanced or surgery alone) in whom the response rate was 41.7% (95% C.I., 27.7–55.6%). The second-line therapy involved 40 patients (72.5% TS-1 failure) in whom the response rate was 22.5% (95% C.I., 9.6–35.4%). The median overall survival was 287 days. The actual dose intensity was 81.7% (85/104) of the planned dose during the first two cycles for both drugs. Commonly observed grade 3/4 adverse events were leukopenia (13.5%), anorexia (3.8%), fatigue (3.8%), and diarrhea (2.9%).There was no neutropenic fever or treatment-related death. Conclusions: These data suggest that Paclitaxel and 5’-DFUR combination chemotherapy is a well tolerated convenient out-patient combination with very promising efficacy for AGC.

No significant financial relationships to disclose.

Muscarinic cationic current in gastrointestinal smooth muscles: signal transduction and role in contraction

1 The muscarinic receptor plays a key role in the parasympathetic nervous control of various peripheral tissues including gastrointestinal tract. The neurotransmitter acetylcholine, via activating muscarinic receptors that exist in smooth muscle, produces its contraction. 2 There is the opening of cationic channels as an underlying mechanism. The opening of cationic channels results in influxes of Ca2+ via the channels into the cell and also via voltage-dependent Ca2+ channels which secondarily opened in response to the depolarization, providing an amount of Ca2+ for activation of the contractile proteins. 3 Electrophysiological and pharmacological studies have shown that the cationic channels as well as muscarinic receptors exist in many visceral smooth muscle cells. However, the activation mechanisms of the cationic channels are still unclear. 4 In this article, we summarize the current knowledge of the muscarinic receptor-operated cationic channels, focusing on the receptor subtype, G protein and other signalling molecules that are involved in activation of these channels and on the molecular characteristics of the channel. This will improve strategies aimed at developing new selective pharmacological agents and understanding the activation mechanism and functions of these channels in physiological systems.

Results of duct-to-mucosa pancreaticojejunostomy for pancreaticoduodenectomy Billroth I type reconstruction in 100 consecutive patients

BACKGROUND

This study retrospectively analyzed 100 consecutive patients who underwent pancreaticoduodenectomy (PD) and pylorus-preserving PD (PPPD) with a Billroth I type reconstruction and pancreaticojejunostomy by duct-to-mucosal anastomosis using a continuous running suture.

STUDY DESIGN

Seventy patients underwent PD and 30 patients PPPD for pancreatic cancer in 33, bile duct cancer in 28, ampullary or duodenal tumor in 22, chronic pancreatitis in 8, and other gastrointestinal cancer in 9. Postoperative pancreatic anastomotic leakage was diagnosed from skin excoriation around the drain site, and was defined as a high concentration of amylase in drainage fluid or leakage demonstrated on x-ray.

RESULTS

The mortality rate was 2% overall (2.8% in PD, 0% in PPPD). The morbidity rate was 23% overall (12.8% in PD, 46.7% in PPPD). Pancreatic anastomotic leakage was 4.0% overall (2.8% in PD, 6.7% in PPPD).. The incidence in the ampullary or duodenal tumors was 9.1% overall (0% in PD, 14.3% in PPPD). Biliary leakage occurred in four patients, 4.0% overall (4.3% in PD, 3.3% in PPPD), intraabdominal hemorrhage in 2% (2.8% in PD, 0% in PPPD), and lethal anastomotic leakage in one patient, overall rate 1% (1.4% in PD, 0% in PPPD). Delayed gastric emptying had the highest morbidity and was seen exclusively in PPPD (39.3%).

CONCLUSIONS

A simple continuous running suture and parachuting for duct-to-mucosal pancreaticojejunostomy makes pancreaticoduodenectomy a safe procedure, even in a Billroth I type reconstruction.

Ab initio structure determination of monoclinic 2,2-dihydroxymethylbutanoic acid from synchrotron radiation powder diffraction data: combined use of direct methods and the Monte Carlo method

The crystal structure of 2,2-dihydroxymethylbutanoic acid (C(6)H(12)O(4)) in monoclinic form has been determined ab initio from synchrotron radiation powder diffraction data. Two O and five C atoms were first derived by direct methods. Two missing O atoms and one C atom were found by the Monte Carlo method without applying constraint to their relative positions. Positional and isotropic displacement parameters of these non-H atoms were refined by the Rietveld method. Molecules are linked by hydrogen bonds and they make sheet-like networks running parallel to the (010) plane. The Monte Carlo method is demonstrated to be a powerful tool for finding missing atoms in partially solved structure.

Continuous measurement of targeted promoter activity by a secreted bioluminescence reporter, Vargula hilgendorfii luciferase

The promoter activity of growth hormone (GH) was continuously monitored in rat pituitary adenoma cells (GH3) by a secreted bioluminescence reporter, Vargula hilgendorfii (Vh) luciferase. The sensitivity of the reporter was approximately 60-times higher than that of the firefly luciferase. GH3 cells were transfected with a plasmid containing a DNA sequence of the GH promoter (1.8 kb) and a full length of the Vh luciferase cDNA. Using the stable transformants, the Vh luciferase activity was monitored in the plate culture through the bioluminescence of Vh luciferase secreted into the culture medium. The reporter activity was well correlated with GH mRNA as well as GH when the GH promoter activity was activated by thyroid hormone. To develop a continuous monitoring system of the promoter, the reporter activity was sequentially measured in the perfusion system. When the promoter activity of the stable transformants was suppressed by a transcription inhibitor, the reporter activity and GH in the perfusate were simultaneously decreased. The Vh luciferase reporter is a sensitive and convenient tool for continuous and prolonged measurement of promoter activity in living cell culture systems.

Inhibitory effect of TAS-301, a new synthesized constrictive remodeling regulator, on renarrowing after balloon overstretch injury of porcine coronary artery

The purpose of this study was to determine the efficacy and the possible mechanism of action of a recently synthesized drug, TAS-301 [3-bis(4-methoxyphenyl)methylene-2-indolinone], on stenosis after balloon overstretch injury of porcine arteries. We measured the diameter of vessels by angiography and conducted histological analysis. The oral administration of TAS-301 kept dilated the angiographic luminal diameter of injured segment 4 weeks after overstretch injury and reduced calculated stenosis ratio in a dose-dependent manner, significantly reducing it at doses of 30 and 100 mg/kg. Histopathological analysis showed that TAS-301 significantly reduced the adventitial area at doses of 30 and 100 mg/kg with moderate reduction of the neointimal area, resulting in the larger residual lumen. In an in vitro assay, TAS-301 dose dependently inhibited the proliferation of adventitial fibroblasts stimulated by basic fibroblast growth factor or transforming growth factor-beta(1). In addition, the drug reduced adventitial fibroblast-mediated three-dimensional collagen gel contraction. These findings indicate that TAS-301, the first compound developed for targeting the constrictive remodeling, showed a high inhibitory potency on coronary artery stenosis of micropigs after injury, mainly due to inhibition of adventitial fibroblast proliferation and of the contractile ability of myofibroblasts. Our results suggest the strong possibility that TAS-301 may be efficacious for prevention of restenosis after angioplasty and the need to examine the therapeutic usefulness of this drug in clinical trials.

[Diagnosis of urinary disorders using ultra-thin ultrasound probe]

We have developed a new diagnostic instrument, to visualize small or early lesions from inside by introducing a flexible ultra-thin probe (2 mm in diameter) into the urinary system. The frequency of the oscillator is 20 to 30 MHz, so the tomogram obtained by the method is extremely fine compared with the ultrasonogram obtained by the scanning from outside of the body. Three-dimensional reconstruction of tomogram is also realized. This display method is valuable to plan operations, follow the progress of therapy, and obtain well informed consent from the patient. We are now developing systems to bend and twist the tip of the intraureteral probe. They are applications of shape memory alloy, thermo-electric actuator and magnetic torque.

[Development of a new method for sequential monitoring of transcriptional activities of growth hormone genes by a secreted bioluminescence reporter]

The genetic reporter system has been introduced as a tool for sensitive and convenient monitoring of gene expression. In the present study, the promoter activity of growth hormone (GH)-coding gene was sequentially monitored in GH3 cells (rat pituitary adenoma cell-line) by means of bioluminescence which was evoked by a secreted reporter, Vargula hilgendorfii (VH) luciferase. Three kinds of expression plasmids were constructed, which consisted of a rat GH promoter fragment and VH luciferase cDNA, and transfected into GH3 cells. The sensitivity of the reporter was revealed to be extremely high from the dose-response curve of VH luciferase. With the use of the stable transformant, the reporter activity as well as that of GH was sequentially measured in plate culture. The intracellular dynamics of reporter signals was analyzed through the response to inhibitors of transcription, protein synthesis and vesicle transport, which suggested that the overall time from transcription to secretion was essentially identical to those of the VH luciferase and GH although the both proteins took different time course at different intracellular stages. When the GH promoter was activated by triiodothyronine (T3), the reporter activity was enhanced, and well correlating with the amount of GH mRNA, which indicated a reliability of the reporter system. Furthermore, in the present reporter system, a synergistic effect of T3 and dexamethasone was observed not only on the GH transcription but also on the stability of mRNA. It is concluded that the bioluminescence reporter system using the VH luciferase is an excellent tool for sequential monitoring of the GH transcriptional activity.

The effects of FK409 on pulmonary ischemia-reperfusion injury in dogs

FK409 is the first spontaneous nitric oxide (NO) donor known to increase plasma cyclic guanosine 3',5'monophosphate levels. In this study, we evaluated the effect of FK409 on pulmonary ischemia-reperfusion injury in an in situ warm ischemia canine model. Fourteen dogs were divided into two groups, and the FK409-treated group was given 5 micrograms/kg per min FK409. Warm ischemia was induced for 3 h. The arterial partial pressure of oxygen (PaO2), arterial oxygen saturation (SaO2), cardiac output (CO), left pulmonary vascular resistance (L-PVR), and endothelin-I (ET-I) were measured. A histologic study was performed, and polymorphonuclear neutrophils (PMNs) were also counted. The PaO2, SaO2, and L-PVR levels and PMNs after 30 min of reperfusion, ET-I after 2 h of reperfusion, and the 7-day survival rate were significantly (P < 0.05) better in the FK409-treated group than in the control group. The histologic damage was reduced in the FK409-treated group compared to the control group. FK409 appears to have a protective effect in ischemia-reperfusion injury of the lung.

Artificial SMA valve for treatment of urinary incontinence: upgrading of valve and introduction of transcutaneous transformer

This paper is concerned with the development of an artificial urethral valve driven by shape memory alloy actuators, which is attached onto the urethra of a urinary incontinence sufferer for treating the involuntary micturition. Three types of compact cylindrical valves are assembled and their opening and closing functions are examined experimentally. The updated valve is heated and opened by using the transcutaneous energy transformer consisting of a pair of flexible spiral-formed copper wire coils. The experiment using the canine urinary canal verifies that the total system of the valve and the transformer works well as an artificial sphictor muscle and controls the urinary flow through the canal appropriately.

Circadian rhythms and light responsiveness of mammalian clock gene, Clock and BMAL1, transcripts in the rat retina

Circadian expression and light-responsiveness of the mammalian clock genes, Clock and BMAL1, in the rat retina were examined by in situ hydbribization under constant darkness. A small but significant daily variation was detected in the Clock transcript level, but not in BMAL1. Light increased the Clock and BMAL1 expressions significantly when examined 60 min after exposure. The light-induced gene expression was phase-dependent for Clock and peaked at ZT2, while rather constant throughout the day for BMAL1. These findings suggest that Clock and BMAL1 play different roles in the generation of circadian rhytm in the retina from those in the suprachiasmatic nucleus. Different roles are also suggested between the two genes in the photic signal transduction in the retina.

Daily variation and light responsiveness of mammalian clock gene, Clock and BMAL1, transcripts in the pineal body and different areas of brain in rats

Expression patterns of mammalian clock genes, Clock and BMAL1, were examined by in situ hybridization in the pineal body, olfactory bulb, hippocampus and cerebellum in rats under constant darkness. In the pineal, the level of Clock transcript was significantly higher at ZT18 (subjective night) than at ZT6 (subjective day), while the level of BMAL1 transcript was significantly higher at ZT6 than at ZT18. A 30 min light pulse did not affect the transcript levels of Clock nor of BMAL1. The Clock expression in the cerebellum was significantly increased at ZT6 than at ZT18, while no difference was detected in the olfactory bulb and hippocampus at these two phases. The BMAL1 expressions in these areas were similar to the case in the pineal. These findings indicate that the mammalian clock gene, Clock and BMAL1, are expressed differently in the different areas of the brain and the pineal.

Gastric emptying after segmental gastrectomy for early cancer in the middle part of the stomach

BACKGROUND/AIMS

We evaluated the quality of life and gastric emptying in patients who had undergone a segmental gastrectomy to treat early gastric cancer in the middle part of the stomach.

METHODOLOGY

Thirty patients were considered in this study. Their mean age was 65.5 years (range: 44-83). All of the patients were free from recurrence of their cancer in the follow-up period. This ranged from 5 to 50 months (mean 30). Patients were interviewed at regular intervals to assess their quality of life and to note particular complaints. The upper gastrointestinal tract was assessed endoscopically. A gastric emptying study was performed at 3, 6, and 12 months after surgery. The meal used in this dual-phase study had solid and liquid phases. For the solid phase, 74 MBq of 99mTc sulfur colloid was injected into an egg, which was then hard-boiled. For the liquid phase, 18.5 MBq of (111)In-diethyltriaminopenta acetic acid (DTPA) were mixed into 150 ml of a commercial, elentary liquid diet.

RESULTS

Three months after surgery, the patients' main complaints were gastric stasis (25%), heartburn (8%) and belching (8%). The patients gradually became asymptomatic following surgery. Fifty-nine percent were asymptomatic at the 3-month follow-up, 84% at 6 months, and 92% at 12 months. There was no evidence of reflux esophagitis or gastritis after the 3-month follow-up. One patient developed a complicated duodenal ulcer. Initially, the patients all had prolonged gastric emptying of the dual phase meal, compared to normal individuals. The T1/2 for liquid meal emptying was 87+/-18 min at 3 months, 77+/-20 min at 6 months and 50+/-5 min at 1 year after surgery. The last value is the same as for healthy individuals. Solid meal emptying was still prolonged, with an emptying rate of 36+/-9.7% at 2 hours, one year after surgery.

CONCLUSIONS

Segmental gastrectomy patients experienced prolonged gastric emptying in the early post-operative period. This improved in the first year after surgery. The quality of life for patients who underwent segmental gastrectomy has been reasonably good in the follow-up period to date.

Phase-dependent induction by light of rat Clock gene expression in the suprachiasmatic nucleus

To clarify the role of Clock in the photic signal transduction of rat circadian clock, we cloned and sequenced rat Clock and examined the effect of a single light pulse on the Clock mRNA expression in the suprachiasmatic nucleus (SCN) by in situ hybridization. Rats were exposed to a 30 min light pulse ( approximately 300 lx) at one of six circadian phases in constant darkness (DD), and sacrificed 60 min after the light on. In the rats without light exposure, the mRNA level in the SCN was high at ZT (Zeitgeber time) 6 and low at ZT 18 and 22. Light exposure increased Clock mRNA level in the SCN in phase dependent manner. The mRNA level was significantly increased during the subjective night (ZT10-22). The light had no effect on the mRNA level during the subjective day (ZT2 and 6). The Clock mRNA was also detected in the piriform cortex (PC), and increased by light at ZT14. These results suggest that Clock transcription in the SCN is involved in the photic signal transduction of circadian clock in rats.

Segmental gastrectomy for early cancer in the mid-stomach

BACKGROUND/AIMS

We modified the surgical procedure for segmental gastrectomy, which is normally used for peptic ulcers, to treat early gastric cancer of the mid-stomach. In this paper, we describe the surgical technique and its results.

METHODOLOGY

The location of the tumor was confirmed by intra-operative endoscopic examination. An area 2 cm proximal and distal to the tumor was marked with sutures. Firstly, the lymph nodes were dissected from around the perigastric and along the left gastric and common hepatic arteries. Then, a segmental gastrectomy was performed. The greater omentum, omental sac, and vagal nerve, including the hepatic, pyloric and celiac rami, were left intact. An end-to-end gastrogastrostomy was performed using Gambee's sutures and 4-0 monofilament polydioxanone. Gastric drainage was not necessary.

RESULTS

We performed segmental gastrectomies on 30 patients. Tumors less than 1 cm in diameter were found in 4 patients; 1.1-2 cm in 14, 2.1-5 cm in 11, and a tumor exceeding 5.1 cm in one patient. The cancer was confined to the mucosa in 23 patients; in the other 7, it had penetrated the submucosa. No lymph node metastases were found but 2 patients had microscopic invasion or permeation of the lymphatic vessels. One patient required post-operative balloon dilation of the pyloric sphincter for delayed gastric emptying. The remaining patients had no post-operative complications. To date, 29 patients, excluding one who died in a traffic accident, have survived disease-free for a mean of 30 months (range: 7-51). Their body weight and dietary volume returned to pre-operative levels within 12 months of surgery.

CONCLUSIONS

Patients who underwent segmental gastrectomy have had a reasonably good quality of life in the post-operative follow-up to date.

Endoscopic balloon dilation for benign esophageal anastomotic stricture: factors influencing its effectiveness

BACKGROUND/AIMS

The aim of this study was to identify factors that might affect the results of treating benign anastomotic stricture of the esophagus with balloon dilation.

METHODOLOGY

Balloon dilation was performed on 35 patients with benign esophageal anastomotic stricture of the upper (esophageal cancer: 18) or lower (gastric cancer: 15, esophageal varices: 2) esophagus. The procedure was considered effective when patients were able to maintain a solid diet more than 12 months after the last dilation. The follow-up period ranged from 15-130 months (mean: 51 months).

RESULTS

A total of 245 dilations were performed, with an average of 6.6 dilations per patient. Treatment was effective in 29 patients (83%). Balloon dilation was successful when treating strictures shorter than 12 mm in length. The strictures were significantly shorter in patients treated effectively (5.6 vs. 30.8 mm). The diameter of the stricture did not affect the results. All the strictures in the lower esophagus and all those resulting from stapled anastomoses were treated successfully, while the effectiveness of treating strictures in the upper esophagus or those resulting from hand-sewn anastomoses was 67% and 57%, respectively. Strictures without prior leakage were treated effectively 92% of the time, while the success rate fell to 56% if there was a preceding leak. An average of 4.4 dilations were performed in effective cases, while the average was 17.5 dilations in ineffective cases. The number of repeat dilations was correlated with the length of the stricture.

CONCLUSIONS

Balloon dilation can successfully treat strictures shorter than 12 mm long. The correlation equation may be used to predict the number of repeat dilations and treatment results, and is useful for deciding when to use an alternative method to balloon dilation.

Circadian rhythm and light responsiveness of BMAL1 expression, a partner of mammalian clock gene Clock, in the suprachiasmatic nucleus of rats

To clarify whether BMAL1 is involved in the photic signal transduction in the mammalian circadian clock, we examined the effects of a single light pulse on the level of BMAL1 mRNA in the suprachiasmatic nucleus (SCN) of rats by in situ hybridization. Rats were exposed to 30 min light of ca. 300 lux at six different phases in constant darkness and decapitated 60 min later. BMAL1 transcripts in the SCN of the control animals showed a robust circadian oscillation with the highest expression at ZT (Zeitgeber time) 18 and the lowest at ZT2. The light pulse slightly increased the level of BMAL1 transcripts in the SCN. However, the increment did not depend on the phase of light pulse. There was no significant change in the BMAL1 mRNA level up to 120 min after a light pulse at ZT14 and ZT22. These results indicate that BMAL1 transcription is not involved in the photic signal transduction responsible for non-parametric entrainment of the circadian clock in rats.

Phyllodes tumor showing intracystic growth: a case report

A phyllodes tumor often grows rapidly and occasionally contains microcysts; however, the tumor rarely shows a morphologically intracystic pattern. We experienced a rare case of a phyllodes tumor with a solid mass growing into the cyst. A 62-year-old female noticed a tumor in her right breast in January 1995. The tumor grew rapidly and she visited our out-patient clinic in February 1995. On physical examination, a 10 x 8 cm, well defined and movable mass with a smooth surface was palpated in the upper outer quadrant of the right breast. Mammography showed a large tumor shadow in the upper outer quadrant of the right breast without any microcalcification. Ultrasonography revealed a large cystic shadow with a low echoic lesion and solid component with heterogeneous internal echo in the cyst. Under general anesthesia, the tumor was widely excised. The resected specimen was 11.5 x 11 x 11 cm in size and the tumor was not invasive to surrounding tissues. Old bloody fluid was contained within the cyst. The gross appearance showed papillary process protrusions into a central cystic cavity. Histological examination revealed a borderline case of phyllodes tumor. Two years after the operation, she is doing well without any recurrence.