Cell-cycle-dependent invasion in vitro by rat ascites hepatoma cells

The relationship between cell cycle and experimental metastasis of tumor cells in vivo has been investigated, but it remains to be elucidated which step of metastasis, or whether tumor-cell invasion in particular, depends on cell cycle. We previously reported an in vitro cell-monolayer invasion (transcellular migration) assay system, in which the invasive capacity of tumor cells is measured by counting tumor cells penetrating beneath a cultured mesothelial cell monolayer after tumor-cell seeding. Using our invasion assay system, the relationship between invasive capacity and cell-cycle distribution of MMI cells, a highly invasive clone of rat ascites hepatoma AH130, was investigated. Invasive capacity of aphidicolin- or hydroxyurea-synchronized tumor cells enriched in G₁/S—early S-phase cells was about 2 to 6 times higher than that of asynchronous cells. According to time-course experiments to examine the relationship between invasive capacity and the size of fraction of cells in each phase after release from an aphidicolin or a nocodazole block, it was suggested that MMI cells are most invasive in G₁/S-S phase. Phagokinetic assay using colloidal gold particles showed that one possible reason for the enhanced invasiveness might be the increased cell motility in such phases, as suggested by the in vitro invasion assay.     

Heart transplantation

Since February 1999, organ transplantation from brain-dead donors has started in Japan. During the more than 3 years since, 77 patients have received organ transplantations from 19 donors (heart in 13, lung in 10, liver in 17, pancreas-kidney in 6, pancreas alone in 1, small intestine in 1, and kidney in 29). As of April 2002, 116 patients were registered with the Japan Organ Transplant Network as heart transplant (HTx) candidates, and 13 and 8 underwent HTx in Japan and abroad, respectively, while 32 died while on the waiting list. Ten of 13 HTx recipients were implanted with a left ventricular assist device (LVAS; Novacor in 2, TCI-IP in 1, and NCVC in 7). All 13 HTx recipients were alive at the time of writing. Two had several rejection episodes that were treated successfully. Three had infection episodes (pneumonia in 2 and CMV gastritis in 1). Eleven had been released from hospital, and 8 had returned to work.     

Completely Laparoscopic Total Colectomy for Chronic Constipation: Report of a Case

Laparoscopic surgery has had a remarkable impact on the practice of colorectal surgery. However, most operations are performed using a technique of laparoscopic assistance, whereby extracorporeal bowel division and anastomosis are made following laparoscopic mobilization of the bowel. To our knowledge, this is the first report to describe a case of chronic constipation managed by total colectomy with ileorectal anastomosis, performed completely laparoscopically. The diagnosis of slow transit constipation was made by a transit time study. After dissection of the entire colon, the colon to be resected was delivered through the open rectal stump and brought out transanally. The anvil of an intraluminal circular stapler was passed through the rectum into the peritoneal cavity and the end of the open distal rectum was closed with a linear cutting stapler. The anvil of the circular stapler was inserted into the end of the open terminal ileum and fixed with an Endo-Loop, following which an intracorporeal double-stapling anastomosis was performed. By 3 months following surgery, the patient was passing 3–4 stools a day. Thus, we highly recommend this technique as it eliminates the need for a small incision to deliver the resected colon, thereby minimizing the operative time and risk of wound infection. Received: August 23, 2001 / Accepted: January 8, 2002     

Bilateral cervicomediastinal neurofibroma originating from the vagal nerve in a patient with von Recklinghausen's disease: report of a case

A 19-year-old woman with von Recklinghausen's disease was admitted with symptoms of hoarseness. A computed tomography scan showed a bilateral cervicomediastinal tumor. An extirpation of the left cervicomediastinal tumor was performed for the purpose of diagnosis and treatment. On thoracotomy, the tumor, which measured 9 × 8 × 4 cm in size, arose from the intrathoracic vagal nerve and the left tumor was resected with a segment of the vagal nerve and recurrent nerve. The pathological diagnosis of the tumor was a neurofibroma. The tumor on the right side was left untreated due to concerns about possibly causing palsy of the bilateral recurrent nerve and also because of the asymptomatic state of the right tumor. Mediastinal neuofibroma in a patient with von Recklinghausen's disease often arises from the intrathoracic vagal nerve. To our knowledge, this is the first report of bilateral cervicomediastinal neurofibroma originating from the vagal nerves. Received: November 15, 2001 / Accepted: May 7, 2002 Reprint requests to: M. Ohta     

A 50-year history of new drugs in Japan: the developments of antileprosy drugs and their epidemiological aspects

The developments of antileprosy drugs and their influences on the epidemiological aspects of Hansen's disease (leprosy) in Japan are investigated. 1. Hydnocarpus oil (Daifushi-Yu) products were the only useful drugs for the treatment of Hansen's disease (leprosy) in Japan from the early 1900's to just after the World War II. In those days leprosy was considered to be incurable malady. 2. The chemotherapy of leprosy, progressing from 1943 in the United States, was introduced to Japan in 1948. Promin(R) (sulfoxone sodium) for injection in 1948 and Diasone(R), and Promizole(R) for oral use in 1949 were available for the treatment of leprosy patients in the National Hansen's Disease Sanatorium in Japan. Because DDS (dapsone, diaphenylsulfone) was proved to be the main ingredient of sulfone drugs, since 1958 it has been the drug of choice for all forms of leprosy. Monotherapy with DDS has continued for more than 30 years, and sulfone-resistant bacillus has appeared occasionally. 3. Clofazimine (a new type of chemotherapeutic drug) and rifampicin (an antibiotic for tuberculosis) was added to therapy treatment for leprosy in 1996. In 1983, WHO recommended multidrug therapy (MDT) to prevent resistance to sulfones. The Japanese Leprosy Association published "Guidlines" for the Treatment of Hansen's Disease in Japan" in 2000, which proposes a multidrug therapy with rifampicin, DDS, and clofazimine for a 6-month or 2-year treatment. 4. The number of leprosy patients has slowly decreased since the application of chemotherapy with sulfone drugs, and newly infected patients in Japan have decreased to less than 10 per million persons (Figs. 1 & 2). Therefore the "Leprosy Prevention Law" (1953), which compels the controlled isolation of patients, was abolished in 1996. Effective chemotherapy with sulfone and other drugs has changed incurable leprosy to a curable infective disease.     

Effect of SEA0400, a novel inhibitor of sodium-calcium exchanger, on myocardial ionic currents

The effects of 2-[4-[(2,5-difluorophenyl) methoxy]phenoxy]-5-ethoxyaniline (SEA0400), a newly synthesized Na(+)-Ca(2+) exchanger (NCX) inhibitor, on the NCX current and other membrane currents were examined in isolated guinea-pig ventricular myocytes and compared with those of 2-[2-[4-(4-nitrobenzyloxy) phenyl]ethyl]isothiourea (KB-R7943). SEA0400 concentration-dependently inhibited the NCX current with a 10 fold higher potency than that of KB-R7943; 1 microM SEA0400 and 10 microM KB-R7943 inhibited the NCX current by more than 80%. KB-R7943, at 10 microM, inhibited the sodium current, L-type calcium current, delayed rectifier potassium current and inwardly rectifying potassium current by more than 50%, but SEA0400 (1 microM) had no significant effect on these currents. These results indicate that SEA0400 is a potent and highly selective inhibitor of NCX, and would be a powerful tool for further studies on the role of NCX in the heart and the therapeutic potential of its inhibition.     

Modulators of internal Ca2+ stores and the spontaneous electrical and contractile activity of the guinea-pig renal pelvis

1. The role of internal Ca(2+) stores in the generation of the rhythmic electrical and contractile activity in the guinea-pig proximal renal pelvis was examined using intracellular microelectrode and muscle tension recording techniques. 2. Ryanodine (30 microM) transiently increased contraction amplitude, while caffeine (0.5 - 3 mM) reduced contraction amplitude and frequency. Contractility was also reduced by 2-aminoethoxy-diphenylborate (2-APB 60 microM), xestospongin C (1 microM), U73122 (5 microM) and neomycin (4 mM), blockers of IP(3)-dependent release from Ca(2+) stores. 3. 60 mM K(+) saline-evoked contractions were reduced by caffeine (1 mM), U73122 (5 microM) and neomycin (4 mM), but little affected by ryanodine or 2-APB (60 microM). 4. Spontaneous action potentials consisting of an initial spike followed by a long plateau were recorded (frequency 8.6+/-1.0 min(-1)) in small urothelium-denuded strips of proximal renal pelvis. 5. Action potential discharge was blocked in 75 and 35% of cells by 2-APB (60 microM) and caffeine (1 mM), respectively. In the remaining cells, only a truncation of the plateau phase was observed. 6. Cyclopiazonic acid (CPA 10 microM for 10 - 180 min), blocker of CaATPase, transiently increased contraction frequency and amplitude. Action potential durations were increased 3.6 fold. Contraction amplitude and frequency slowly declined during a prolonged (>60 min) CPA exposure. 7. We conclude that the action potential in caffeine-sensitive cells and the shoulder component of caffeine-insensitive action potential arise from the entry of Ca(2+) through Ca(2+) channels. The inhibitory actions of modulators of internal Ca(2+) release were partially explained by a blockade of Ca(2+) entry.     

BK channels play an important role as a negative feedback mechanism in the regulation of spontaneous rhythmic contraction of urinary bladder smooth muscles

Smooth muscles of urinary bladder wall exhibit spontaneous rhythmic contraction which is myogenic in origin. Although the precise mechanism responsible for the generation of this mechanical activity remains to be established, it can be related closely to the action potential (AP) in urinary bladder smooth muscle (UBSM) cell, and may be the fundamental constituent to determine urinary bladder physiological functions to store and micturate urine. In the present study, possible roles of voltage-dependent and Ca(2+)-sensitive K+ (BK) channels, highly expressed in UBSM cells, were examined in the regulation of spontaneous UBSM contraction with reference to the generation of AP. Iberiotoxin (IbTx), a selective BK channel blocker, strongly increased mechanical activity and AP generation in guinea-pig UBSM. In contrast, BK channel openers (NS-1619, niflumic acid; estradiol, tamoxifen: BK channel alpha- and beta-subunit activators, respectively) significantly diminished AP generation and spontaneous mechanical activity. The present study indicates that BK channels play the primary role as a negative feedback element to limit extracellular Ca2+ influx through affecting AP configurations in the generation of UBSM contraction. BK channel openers including beta-subunit activators may be a potentially useful therapeutic remedy for the treatment of urinary bladder dysfunctions such as frequent urination.     

Evidence for the possible involvement of Ca<Superscript>2+</Superscript> entry blockade in the relaxation by class I antiarrhythmic drugs in the isolated pig coronary smooth muscle

Effects of several Na+ channel blockers (i.e., class I antiarrhythmic agents), procainamide, quinidine, lidocaine, mexiletine, propafenone, were investigated in the isolated endothelium-denuded pig coronary artery focusing on the possible involvement of the blockade of Ca2+ channels and/or opening of K+ channels in the relaxant responses.All drugs except procainamide induced a concentration-dependent full relaxation of the coronary artery precontracted with high-KCl (30 mM, 80 mM). Inhibitions by procainamide of both high-KCl-induced contractions were less than 50% even at a concentration of 3 x 10(-2) M. Both high-KCl contractions were diminished by an L-type Ca2+ channel blocker, diltiazem, in a concentration-dependent manner. In contrast, cromakalim failed to inhibit 80 mM KCl-induced contraction. Tetrodotoxin (3 x 10(-5) M) did not affect the relaxant actions of the tested class I antiarrhythmic agents in high-KCl (80 mM)- or prostaglandin F2alpha-contracted muscle. The inhibitions by these class I antiarrhythmic agents of high-KCl-induced contraction were significantly attenuated when extracellular CaCl2 was increased from 2 mM to 20 mM. Furthermore, procainamide, quinidine, lidocaine, mexiletine as well as diltiazem decreased both cytoplasmic Ca2+ level ([Ca2+](cyt)) and muscle tension elevated by high-KCl in fura-2-loaded coronary preparations.These findings suggest that blockade of voltage-gated Ca2+ channels is involved in the relaxing action of these class I antiarrhythmic drugs in pig coronary artery. Blockade of Na+ channel and/or opening of K+ channels does not seem to play the principal role in the mechanism by which these antiarrhythmic drugs relax coronary artery.