Prostaglandin E2 production by endogenous secretion of interleukin-1 in decidual cells obtained before and after the labor

Previous reports revealed that interleukin-1 (IL-1) was involved in the process of premature labor in the cases with intrauterine infection. However, the roles of the cytokine in normal spontaneous labor remain uncertain. The present studies aimed at determining the involvement of the cytokine in prostaglandin (PG)E2 production during labor by the third trimester decidual cells. The cells were obtained at the time of normal spontaneous delivery (NVD) and elective cesarean section (ECS). The NVD cells produced significantly more amount of PGE2 than the ECS cells and the both cells responded to the addition of IL-1 beta to increase PGE2 production. A specific inhibitor of cyclooxygenase-2 (COX-2), NS398, decreased basal PGE2 production and inhibited the stimulatory effect of IL-1 beta in a dose dependent manner in NVD cells. The NVD cells secreted more amount of IL-1 beta than the ECS cells and contained more amount of preprocessed 31kD IL-1 beta inside the cells. The addition of recombinant soluble human IL-1 receptor (type I) not only blocked the effect of IL-1 beta on PG secretion, but significantly reduced the basal production of PGE2 by NVD cells. These results indicate that decidual PG production depends upon COX-2 after the onset of labor. Besides it seems likely that endogenously produced IL-1 beta may be involved in autocrine or paracrine fashion in inducing COX-2 after the onset of labor.

GM-109: a novel, selective motilin receptor antagonist in the smooth muscle of the rabbit small intestine

The pharmacological properties of the cyclic peptide Phe-cyclo[Lys-Tyr(3-tBu)-beta Ala-].trifluoroacetate (GM-109), a selective motilin antagonist, were investigated in the smooth muscle of the rabbit small intestine. GM-109 (0.1-3 microM) competitively inhibited contractions induced by porcine motilin (pMTL) in rabbit isolated duodenum longitudinal strips, with a pA2 value of 7.37 +/- 0.24. However, the contractile response to acetylcholine, to substance P, to prostaglandin F2 alpha and to KCl was unaffected by 10 microM GM-109 in the same preparation. Both GM-109 and pMTL competitively inhibited 125I-pMTL binding to motilin receptors in a homogenate of the rabbit small intestinal smooth muscle tissue. The pKi value of GM-109 and the pKd value of unlabeled pMTL were 7.99 +/- 0.04 and 9.25 +/- 0.06 (each n = 5), respectively. These results indicate that GM-109 is a selective and competitive motilin receptor antagonist in the smooth muscle of the rabbit small intestine. Thus this compound may be a useful pharmacological tool for examining the functional role(s) of motilin.

Properties of single potassium channels in guinea pig hepatocytes

The patch-clamp technique of cell-attached and inside-out configurations was used to study the single potassium channels in isolated guinea pig hepatocytes. The single potassium channels in isolated guinea pig hepatocytes were recorded at different K+ concentrations. A linear single-channel current-voltage relationship was obtained at the voltage range of -80 to -20 mV with slope conductance of 70 +/- 6 pS (n = 10). Under symmetrical high K+ concentration of 148 mM in the cell-attached patch membrane, the I-V curve exhibited a mild inward rectification at potentials positive to + 20 mV. The values of reversal potential was +5 +/- 2 mV (n = 10). When the external potassium concentration ([K+]o) was decreased to 74 mM and 20 mM, the slope conductance was decreased to 48 +/- 2 pS (n = 4) and 24 +/- 3 pS (n = 3), respectively. The reversal potential was changed by 58 mV for a tenfold change in [K+]o, indicating that this channel was highly selective for K+. Open probabilities (Po) of the channel were 73-93% without apparent voltage dependence. The distributions of open time of the channels were fitted to two exponentials, while those of closed time were fitted to three exponentials, exhibiting no voltage dependence. The success rate of K+ channel activity to be recorded was 28% at room temperature, and there were no increases in the success rate nor in the channel opening probabilities at a temperature of 34-36 degrees C. Po in inside-out patches was not changed by application of 1 microM Ca2+ nor 1 mM Mg2+ to the internal side of patch membranes. It is concluded that a novel type of the K+ channels in guinea pig hepatocytes had different properties of slope conductance, channel kinetics, and sensitivity to [Ca2+]i, from those in other species.

An early gallstone clearance following repeat piezoelectric lithotripsy

Piezoelectric extracorporeal litotripsy was performed in 128 symptomatic patients with radiolucent gall-bladder stones to assess the significance of disintegration in fragment clearance. Up to 10 repeat lithotripsy sessions were scheduled to achieve a fragment target size of < 3 mm. Fragmentation assessed by the size of the largest fragments after the last session was graded into three classes. I: sludge-like disintegration, 18%; II: < 3 mm (mean +/- s.d., 1.7 +/- 0.5 mm), 56%; and III: > or = 3 mm (3.3 +/- 0.6), 26%. All patients were initially subjected to lithotripsy alone. Bile acid dissolution therapy was started only when ultrasonography failed to show the evidence of decrease in the < 3 mm fragments during a 1 month follow up. Finally, 69 patients (54%) were treated by lithotripsy alone, and the remaining 59 received additional dissolution therapy at a mean period of 2.5 months after the initial lithotripsy. The rate of complete clearance in class I, II and III patients was 91, 42 and 10% at 6 months and 100, 68 and 49% at 18 months, respectively. Significant differences were noted between the three fragmentation grades (I vs II, III, P < 0.0001; II vs III, P < 0.02). The patients with complete clearance within 6 months were seen only in those treated by lithotripsy alone, while the majority (87%) of patients with complete clearance during the later period were seen in those treated by additional dissolution therapy. We conclude that a high degree of fragmentation appears to lead stones to an earlier period clearance, and reduce the need for dissolution therapy.

Establishment and characterization of stromal cell lines that support differentiation of murine hematopoietic blast cells into osteoclast-like cells

This study aimed to establish and characterize a new stromal cell line that supports the proliferation of hematopoietic blast cells and their differentiation into osteoclast-like cells. Cells isolated from the calvaria of neonatal Balb/c mice were subcultured every 2 to 4 days at 1.2 x 10(4) cells/cm2. After 18 passages the cells had become immortalized and were designated as MCHT-1. MCHT-1 cells were found to support the proliferation of hematopoietic blast cells and their differentiation into osteoclast-like cells when these two cells were co-cultured in the presence of 1 alpha,25(OH)2D3 and dexamethasone. However, because the MCHT-1 cells showed heterogeneity, cloning was performed and each clone was characterized. All the clones obtained supported the proliferation of hematopoietic blast cells and their differentiation into osteoclast-like cells irrespective of their obvious differences in growth capacities and cytochemical characteristics. However, the time-course of the appearance of osteoclast-like cells differed among clones. The supportive effect of these clonal stromal cells on differentiation of hematopoietic blast cells into osteoclast-like cells was completely dependent on the presence of 1 alpha,25(OH)2D3 and dexamethasone. These clonal MCHT-1 cells are expected to be useful for precise analysis of the proliferation and differentiation of osteoclasts.

Comparative studies with 15(R)-15-methylprostaglandin E2 (arbaprostil) in rat femoral arterial preparations in vivo and in vitro

1. The vasodilator responses to 15(R)-15-methylprostaglandin E2 (arbaprostil), prostaglandin (PG) E2 and acetylcholine (ACh) administered into the femoral artery intra-arterial (i.a.) of anesthetized rats were attenuated by i.a. infusion of methylene blue, while that to nicardipine remained unaffected in the same dose-range of methylene blue. 2. The vasocontractor responses to arbaprostil and PGE2 in isolated femoral arterial strips were significantly potentiated by removal of the endothelium and the presence of NG-monomethyl L-arginine, while that to U-46619 remained unaffected under the same condition. 3. The present result indicates that the endothelium-dependent mechanism may play an important role in the vascular response to arbaprostil, like PGE2 and ACh.

Possible role of the endothelium on the vascular response to prostaglandin E2 in rat femoral arterial preparations in vivo and in vitro

The mode of action of prostaglandin E2 was investigated on the rat femoral arterial vascular bed in vivo and on the isolated femoral artery in vitro. In in vivo preparations, prostaglandin E2 (0.01-0.3 microgram), as well as acetylcholine (0.01-0.3 microgram) and nicardipine (0.1-3 micrograms), administered into the femoral artery (i.a.), elicited a dose-dependent increase (vasodilatation) in femoral blood flow, without markedly influencing systemic blood pressure or heart rate. The vasodilator response to prostaglandin E2 was not affected by i.v. pretreatment with atropine (0.5 mg/kg), propranolol (0.5 mg/kg), glibenclamide (20 mg/kg) or NG-monomethyl-L-arginine (100 mg/kg), whereas it was significantly attenuated, like that to acetylcholine, by i.a. infusion of methylene blue. However, methylene blue did not affect the vasodilator response to nicardipine even at a dose sufficient to attenuate the responses to prostaglandin E2 and acetylcholine. In isolated femoral arterial strips, prostaglandin E2 (3 x 10(-8) - 3 x 10(-4) M), phenylephrine (3 x 10(-8) - 1 x 10(-4) M) and U46619 (1 x 10(-9) - 1 x 10(-6) M) induced a concentration-dependent vasoconstriction. The vasoconstrictor responses to prostaglandin E2 and phenylephrine were significantly potentiated by removal of the endothelium and by the presence of methylene blue (3 microM) or NG-monomethyl-L-arginine (100 microM), whereas those to U46619 remained unaffected in the same conditions. The present results indicate that the endothelium may play a role in the vascular response to prostaglandin E2.

A chimeric analog of human and salmon calcitonin eliminates antigenicity and reduces gastrointestinal disturbances

The minimum region in salmon calcitonin (sCT) which induces antigenicity and gastrointestinal disturbances has been identified by examining the cross-reactivity of several sCT fragments and CT analogs with antisera from sCT-treated patients, and by examining inhibition of gastrointestinal motility of these sCT fragments and CT analogs in conscious dogs. Sixteen residues at the N-terminus of sCT comprised the minimum fragment capable of inducing both activities. Human CT (hCT) showed no antigenicity and a four-order weaker inhibition of gastrointestinal motility than sCT. Based on these data, we synthesized the human and salmon chimeric CT, ACT-15, in which the 16 N-terminal residues were those of hCT and the 16 C-terminal residues were those of sCT. ACT-15 had no cross-reactivity with the antisera and had almost the same weak gastrointestinal inhibition effect as hCT in dog and rat models. Nevertheless, it retained a hypocalcemic activity and an analgesic activity comparable to sCT. These results suggest that the amino acid residues in the N-terminal half of CT are responsible for the formation of antibodies and the induction of gastrointestinal disturbances, but may not influence calcium metabolism or analgesia. Clinical studies of ACT-15 will be needed to confirm this hypothesis.

Effects of cisapride on gastrointestinal motor activity and gastric emptying of disopyramide

The effects of cisapride on the gastrointestinal contractile activity and pharmacokinetics of disopyramide were determined in beagle dogs and patients with arrhythmia. In the animal experiments, the gastric motor index was significantly decreased by i.v. administration of disopyramide in a dose-dependent fashion. The peak decrease of the motor index was observed within 5 min after i.v. injection of disopyramide; the motor index then recovered gradually to the level present prior to drug administration. I.v. administration of cisapride (0.5 mg/kg) markedly increased gastrointestinal contractile activity following the decrease induced by disopyramide pretreatment (5 mg/kg, i.v.). In the clinical studies, the gastric emptying test was performed using the acetaminophen method. A significant correlation between plasma concentrations of disopyramide and gastric emptying time has been found (p < 0.001). The combination of disopyramide (100 mg t.i.d.) and cisapride (2.5 mg t.i.d.) significantly increased gastric emptying compared with that induced by disopyramide alone. The peak plasma concentration of disopyramide in association with cisapride oral administration was significantly higher, and the apparent absorption rate constant and lag time of disopyramide were about 2-fold higher and 2-fold shorter, respectively, than for disopyramide alone. Cisapride, acting as a cholinergic agonist, may counteract the anticholinergic effect of disopyramide on gastric motility. As a factor influencing drug absorption, gastric emptying is of importance, as it determines the rate of drug delivery to the small intestine. Therefore, the oral administration of disopyramide with cisapride may be useful for patients with delayed gastric emptying.

Ca(2+)-activated K+ channel is present in guinea-pig but lacking in rat hepatocytes

The mechanisms of norepinephrine-induced membrane responses in isolated hepatocytes from guinea-pigs and rats were compared using the suction-pipette, patch-clamp method, and intracellular Ca2+ concentration ([Ca2+]i) was measured using the Ca2+ fluorescent dye, Quin 2. The resting membrane potentials of isolated guinea-pig hepatocytes were -50 +/- 1 mV (mean +/- SD; n = 38), which is similar to that previously reported in rat hepatocytes by Sawanobori et al. (J Cell Physiol 139: 580-585, 1989). In guinea-pig hepatocytes, norepinephrine (6 microM) caused a membrane hyperpolarization, and norepinephrine (6 microM) or Ca(2+)-ionophore (A23187) (0.4 microM) caused a corresponding outward current. The sensitive current produced by norepinephrine and Ca(2+)-ionophore reversed its polarity at -74 +/- 9 mV (n = 7). The single channel recorded by cell-attached patch and inside-out patch had mean conductance of around 20 + 1 pS and was activated by 1 microM [Ca2+]i. On the other hand, neither norepinephrine (6-20 microM) nor Ca(2+)-ionophore (A 23187) (0.4 microM) caused any change in membrane potential and current in rat hepatocytes, whereas norepinephrine increased [Ca2+]i both in rat and guinea-pig hepatocytes to a similar degree. In the single-channel recording, we recorded single channels that had a mean conductance of 109.8 +/- 17.7 pS different from around 20 pS in guinea-pig. In inside-out patches, increased Ca2+ concentration from 10(-6) to 10(-3) M at the intracellular face of the membrane did not modify the single channel of rat hepatocytes. These results indicate that increased [Ca2+]i activates this channel in guinea-pigs, but that the channel activated by increased [Ca2+]i is lacking in rat hepatocytes membrane. Therefore, different mechanism operates in different species of liver cells to keep the constant state.

Acid-promoted epimerization of arbaprostil, 15(R)-15-methylprostaglandin E2, elicits gastric antisecretory activities in rats

Gastric acid antisecretory activities of 15(R)-15-methylprostaglandin E2 (arbaprostil) preincubated or not preincubated with 0.9% physiological saline, the pH of which was precisely adjusted to less than 4.30, were examined in pylorus-ligated rats, and compared with those of 15(S)-15-methylprostaglandin E2 (15(S), epimer of arbaprostil). 15(S), unlike arbaprostil without preincubation, when s.c.-administered to rats significantly inhibited gastric acid secretion in a dose-dependent manner (30-300 micrograms/kg). However, arbaprostil preincubated at 37 degrees C for 30 min with 0.9% saline, at pHs of 4.30, 2.75 and 1.20, respectively, showed the following order of pH-dependent antisecretory activities: 1.20 greater than 2.75 greater than 4.30. An increase in 15(S) formation from arbaprostil in a pH-dependent manner was also observed by radioisotopic experiments under the same incubation conditions using [3H]-labeled arbaprostil. The present result suggests that the gastric antisecretory effect of arbaprostil can be mainly explained in terms of the formation of 15(S) after oral administration.

Gastric antisecretory activity of 15(R)-15-methylprostaglandin E2, arbaprostil, in dogs

The gastric antisecretory activity of 15(R)-15-methylprostaglandin E2 (arbaprostil) was compared with that of natural prostaglandin (PG) E2 in Pavlov pouch dogs. Arbaprostil significantly inhibited pentagastrin- and food-stimulated gastric secretion when it was administered directly into the pouch at a dose of 10-30 micrograms/pouch and 30-300 micrograms/pouch, respectively. Natural PGE2, however, was inactive up to 1000 micrograms/pouch. The data indicate that arbaprostil is a potent, long-acting orally active antisecretory drug that may be useful for the treatment of peptic ulcer disease.

Separation and purification of uridine diphosphate-glucuronosyltransferases by chromatofocusing on a high-performance liquid chromatograph

A rapid method for the separation and purification of uridine diphosphate-glucuronosyltransferases (GT) was developed with the use of chromatofocusing on a high-performance liquid chromatograph. GT isoenzymes solubilized from hepatic microsomes of Wistar rats were separated on a Mono P column, a pre-packed column for chromatofocusing. Using 4-nitrophenol, testosterone and androsterone as substrates, four fractions with different GT activities were separated in a pH gradient from 9.5 to 7.0. Two isoenzymes, testosterone GT and androsterone GT were purified to apparent homogeneity. They were eluted at pH 8.9 and 8.0 and had subunit molecular weight values of 50000 and 52000, respectively. Approximately 10 mg of solubilized microsomal proteins was applied and the elution was completed within 2 h. Addition of N-nitrodiethylamine, an in vitro activator of GT activity, enhanced the GT activity toward 4-nitrophenol in the three fractions. This chromatographic analysis confirmed the absence of androsterone GT isoenzyme in LA Wistar rats, a mutant strain in terms of androsterone glucuronidation.

Electrophysiological properties of isolated rat liver cells

The electrophysiological properties of isolated rat liver cells were studied using the patch clamp method in whole-cell configuration. The membrane potential in isolated hepatocytes was -42 +/- 7 mV (n = 20). The input resistance (Rin) and the time constant (tau m) were 51 +/- 17 M (the range of 34 to 180 M omega) (n = 20) and 4.2 +/- 1.0 msec (the range of 3 to 16.5 ms) (n = 20). Assuming that the specific membrane capacitance is 1 microF/cm2, the membrane resistance and membrane capacitance were 42. +/- 9.0 K omega cm2 and 87 +/- 27 pF. These values indicate that isolated rat hepatocytes are not abnormally permeable or leaky. The current-voltage relationship was linear with no rectification. The depolarizing pulse from the resting potential did not induce fast or slow inward currents even when norepinephrine or high Ca2 (3.6 mM) were applied. This indicates that there is no voltage-sensitive Ca2+ channel in the isolated hepatocytes.

Effects of administration of N-nitrosodialkylamines and N-nitrodiethylamine on hepatic UDP-glucuronosyltransferase activity in Wistar rats

N-Nitrosodiethylamine (NEN) and N-nitrodiethylamine (NEA) are carcinogens and in vitro activators of hepatic UDP-glucuronosyltransferase (GT) toward 2-aminophenol (AP) and 4-nitrophenol (NP). In this communication, they were intraperitoneally administered to male Wistar rats for 7 days and GT activities were determined towards AP, NP, phenolphthalein (PH) and testosterone (TS). Administration of 30 or 20 mg/kg dose of NEN caused marked decrease of liver and body weights, and did not affect hepatic GT activities. Injection of 10 mg/kg dose of NEN did not diminish liver and body weights, and increased the maximally activated GT activities toward AP and NP. In contrast, 30 mg/kg dose of NEA, did not affect either liver and body weights or GT activities. N-Nitrosodimethylamine (NMN), which is a carcinogen and a weak in vitro AP GT activator, was more toxic than NEN, and 3.6 mg/kg dose of NMN appears to induce GT toward NP and AP. Administration of 46.5 mg/kg N-nitrosodibutylamine (NBN), which is a carcinogen but not a GT activator, did not affect GT activities or liver body weights.

[Receptive relaxation of the canine stomach]

Receptive relaxation of the stomach by feeding was studied in 5 conscious dogs by means of chronically implanted force transducers on the gastric body and antrum. It was found that only the gastric body but not antrum relaxed by feeding, and magnitude of the relaxation of the gastric body was linearly related to the volume (5, 10 and 20 g/kg) of test meals, given once or in multiple times. Secondly, in the study of pharmacological blockers, it was found that atropine, hexamethonium and phentolamine significantly inhibited relaxation, while naloxone and proglumide significantly suppressed relaxation in 3 dogs. Propranolol and domperidone did not influence on receptive relaxation. It is concluded that receptive relaxation of the stomach is mainly mediated through a cholinergic reflex, however, involvement of neurotransmitters other than acetlycholine is suggested in the regulation of receptive relaxation.

Carcinogenicity examination of quercetin and rutin in ACI rats

Carcinogenicity of quercetin and rutin were examined in inbred ACI strain rats. Rats were given a diet containing 1% or 5% quercetin or 5% rutin for 540 days, or 10% quercetin and 10% rutin for 850 days. Rats in control groups were fed a normal basal diet. Most tumors found in experimental groups were also found in the corresponding control groups. Furthermore, there was no significant difference between the incidence of tumors in the experimental or control groups (P greater than 0.05). Thus, quercetin and rutin tested were not shown to be carcinogenic to ACI rats.

Effect of storage on carcinogenic activity of bracken fern

Effect of storage on carcinogenic activity of bracken fern was examined with inbred strain ACI rats of both sexes. The experiment was broken down into 3 groupings: Group I received a diet containing fresh dry bracken powder: Group II received a diet which contained the same dry bracken powder used in Group I but preserved for 1 year at 4 degrees C (Group II-C) or room temperature (Group II-R); Group III received the diet containing bracken powder preserved for 2 years at 4 degrees C (Group III-C) or room temperature (Group III-R). Three control groups corresponding to Groups I, II and III were fed a normal basal diet. Significant differences in incidence of ileal tumors were observed between Group I and both groups of Group III and latent period of intestinal tumors in Group II or III was longer than that of Group I. The results indicate a decreased carcinogenic activity of bracken fern by preservation.

CArcinogenic activity of clivorine, a pyrrolizidine alkaloid isolated from Ligularia dentata

The carcinogenic activity of clivorine, a pyrrolizidine alkaloid isolated from Ligularia dentata, was studied in inbred ACI rats. Twelve animals in the experimental group received a 0.005% solution of clivorine in drinking water for 340 days and survived beyond 440 days after the beginning of the experiment. Of this group, 8 developed tumors in the liver; 2 developed hemangioendothelial sarcomas, and 6 developed neoplastic nodules. The hemangioendothelial sarcoma showed metastasis in the lung of one rat. No tumors were observed in the liver of the control animals.

Chromosomal aberrations and mutation in cultured mammalian cells induced by pyrrolizidine alkaloids

4 pyrrolizidine alkaloids, heliotrine, lasiocarpine, petasitenine, and senkirkine, were tested for their effects of V79 Chinese hamster cells. All the alkaloids produced cytoplasmic vacuolization, and caused cellular and nuclear enlargement. Chromosomal aberrations were induced in cells treated with the alkaloids. Heliotrine and petasitenine induced interchromosomal exchanges, and lasiocarpine and senkirkine caused chromatid gaps. All the alkaloids induced an 8-azaguanine-resistant mutation in V79 cells by direct treatment for 48 h. Mutation was also induced by treatment with the alkaloids for 1 h in the presence of a metabolic activation system.

Induction of hepatic tumors in rats by senkirkine and symphytine

The carcinogenicity of the pyrrolizidine alkaloids senkirkine and symphytine was studied in male inbred ACI rats. Animals were divided into 3 groups: Group I received ip injections of freshly prepared senkirkine at a dose of 10% of the median lethal dose (LD50) twice weekly for 4 weeks and then once a week for 52 weeks. Group II received ip injections of symphytine at a dose of 10% of the LD50 by the same injection schedule as in group I. The control group was given ip injections of a 0.9% NaCl solution following the same injection schedule as in experimental groups. All group I rats survived for more than 290 days after the start of injections, and 9 of 20 rats developed liver cell adenoma. All group II animals survived for more than 330 days after the start of injections. Of 20 rats, 4 had liver tumors, 3 had hemangioendothelial sarcomas, and 1 had liver cell adenoma. The hemangioendothelial sarcomas showed metastasis in the lungs of 2 rats. The control group had no liver tumors.