Acetaminophen-derived activation of liver microsomal glutathione S-transferase of rats

Effect of acetaminophen on glutathione (GSH) S-transferase and related drug metabolizing enzymes was studied in vivo. Rats were given acetaminophen (250 mg/kg, i.p.) 24 hr after the treatment with 3-methylcholanthrene (25 mg/kg, i.p.) and killed by decapitation at indicated times. Liver microsomal GSH S-transferase activity was increased to 331%, 193% and 158% of the control level at 3, 6 and 12 hr, respectively, after the administration of acetaminophen, while GSH content in the liver was markedly decreased at 3 and 6 hr. The increase in the transferase activity was not recovered by the treatment with dithiothreitol. Microsomal GSH peroxidase activity was significantly enhanced at 3 hr. Cytosolic GSH S-transferase and aniline hydroxylase in microsomes were gradually decreased with the increase in the time after administration of acetaminophen. Vmax values of both GSH S-transferase and GSH peroxidase activities in microsomes were increased at 3 hr. Two Km values were obtained for the peroxidase in the control, while only one was observed after the acetaminophen treatment. These results indicate that acetaminophen is converted via cytochrome P-450 to the reactive intermediate N-acetyl-p-benzoquinone imine, which binds to microsomal GSH S-transferase, resulting in the activation of the enzyme.

Effects of typical and atypical antipsychotic drugs on freezing behavior induced by conditioned fear

A typical antipsychotic drugs (atypical APDs), such as clozapine, ORG5222, and olanzapine, have been suggested to possess anxiolytic activity in the conflict test and elevated plus-maze test, while several studies have suggested that typical APDs are not anxiolytic in several models of anxiety. We investigated the effects of typical and atypical APDs on the acquisition and expression of conditioned fear-induced freezing. Drugs were administered subcutaneously to male Sprague-Dawley rats 30 min before foot shock stress (the VI60s schedule, 2.5 mA for 30 min). Twenty-four hours after foot shock, freezing behavior of rats was observed in the shock chamber without shocks. The atypical APD clozapine (0.3-10 mg/kg) dose-dependently inhibited the acquisition of conditioned freezing. Candidates for atypical APDs, ORG5222 (0.1-1 mg/kg), olanzapine (1-10 mg/kg), and raclopride (3-30 mg/kg), also reduced the acquisition of conditioned freezing in a dose-dependent manner. Typical APDs, haloperidol (3 mg/kg), spiperone (0.1-1 mg/kg) and nemonapride (1 mg/kg) had significant inhibitory effects on the acquisition of conditioned freezing, but their effects were reduced at higher doses. Chlorpromazine, a typical APD, showed about 50% inhibition of the acquisition of conditioned freezing at the dose of 10 mg/kg, but did not reveal significant inhibition at any of the doses (3-30 mg/kg). The ED50S (mg/kg) for inhibiting the acquisition of conditioned freezing significantly correlated with the Ki values for D4 dopaminergic receptors, but not with the Ki values for other monoamine and acetylcholine receptors. On the other hand, clozapine or haloperidol did not change the expression of conditioned freezing. These results suggest that protective effects of clozapine and other antipsychotic drugs on the acquisition of conditioned freezing may be mediated by blockade of D4 receptors.

Lingual factors enhance the increase of ornithine decarboxylase activity in rat jejunal mucosa after feeding

Luminal nutrients are the main factors that stimulate ornithine decarboxylase (ODC) activity in rat intestinal mucosa following feeding. The aim of the present study was to determine whether lingual (oral) factors are related to the increase in jejunal ODC activity after feeding. ODC activity in the jejunum and liver was measured 3 hours after refeeding of 48-hour fasted rats. In the first experiment, rats were refed with a regular pellet, powder, or liquid diet. In the second experiment, rats were infused with the liquid diet through a gastric infusion tube following 48 hours' fasting. In the third experiment, the experimental rats had a gastric fistula that allowed free drainage from the stomach of all ingested liquid diet. In the fourth experiment, a truncal vagotomy was performed 1 week before the experiment. The increase of ODC activity in the jejunum of rats fed with the liquid diet was less than that of rats fed with the pellet diet or powder diet. The increase of ODC activity in the jejunal mucosa of rats infused through the gastric tube was less than that of rats fed per os, and the increase of ODC activity in the liver did not differ between these experimental groups. ODC activity did not increase in rats with a gastric fistula. Vagotomy did not affect the increase of jejunal ODC activity after feeding. In conclusion, the increase of ODC activity after feeding was attenuated in rats in which the diet was given by bypassing the mouth. This indicates that lingual factors enhance the increase of ODC activity in the jejunal mucosa after feeding, but the lingual factors alone do not increase ODC activity in the jejunum.

Effects of footshock stress on regional brain monoamine metabolism and the acquisition of conditioned freezing in rats previously exposed to repeated methamphetamine

1. Effects of footshock stress on regional brain DA and 5-HT metabolism and the acquisition of conditioned fear in male Wistar-King rats previously exposed to repeated MA were examined. 2. MA-pretreated rats exhibited more freezing than control rats in the conditioned fear test. 3. The HVA levels in the striatum was elevated by footshock only in MA-treated rats but not saline-treated rats. Furthermore, MA-treated rats showed increased metabolism of DA in the mPFC, even when placed in the shock chamber without shocks. 4. The brain serotonergic responsiveness to fear conditioning was also attenuated by repeated administration of MA. 5. These results suggest that not only the brain DA systems but also the brain 5-HT systems play an important role for the development of MA-induced emotional hypersensitivity to stress.

Effect of citalopram, a selective serotonin reuptake inhibitor, on the acquisition of conditioned freezing

The present study examined the effects of the selective serotonin (5-hydroxytryptamine, 5-HT) reuptake inhibitor citalopram on the acquisition of conditioned freezing, an index of anxiety. Acute treatment with citalopram (1-10 mg/kg) dose dependently prevented the acquisition of conditioned freezing, while acute treatment with noradrenaline or dopamine reuptake inhibitors failed. The acute effect of citalopram was not antagonized by the 5-HT1A receptor antagonist NAN190, 1-(2-methoxyphenyl)-4-[4-(2-phthalimmido)butyl]piperazine or the 5-HT2A/2C receptor antagonist ICI169,369, 2-(2-dimethylaminoethylthio)-3-phenylquinoline hydrochloride. These results indicate that selective 5-HT reuptake inhibitors reduce not only the expression of conditioned freezing as reported previously, but also the acquisition of conditioned freezing. Both these effects of selective 5-HT reuptake inhibitors may be related to their clinical efficacy in the treatment of anxiety disorders.

Postabsorptive factors are important for satiation in rats after a lipid meal

We examined satiation after intraduodenal infusion of triglyceride with or without Pluronic L-81 (L-81) in rats. L-81 suppresses lipid transport into mesenteric lymph by preventing the formation of chylomicrons. Under unrestrained conditions, a lipid emulsion was infused into 24-h fasted rats intraduodenally for 8 h. After the infusion, food intake during the first 30 min and blood samples were measured. Food intake after the 8-h lipid infusion decreased significantly (-75%) compared with that of rats infused with vehicle only, and the effect of the lipid meal was time dependent. The satiation effect of the lipid was lost as a result of L-81 treatment, but food intake was still significantly decreased (-22%). The loss of inhibition of food intake by the feeding of lipid plus L-81 was totally reversed by the cessation of L-81 infusion. In rats infused with the lipid emulsion, plasma levels of triglyceride and apolipoprotein A-IV increased significantly. This increase was abolished by the presence of L-81 in the lipid infusate. The present study indicates that postabsorptive factors are important for anorexia observed after a lipid meal in addition to preabsorptive factors. This study further supports our previous conclusion that apolipoprotein A-IV is an important postabsorptive factor for satiation after a lipid meal.

Congenital melanoma: a case suggesting rhabdomyogenic differentiation

A newborn girl had some subcutaneous masses within a giant congenital melanocytic nevus in the left parietal area. Microscopic examination revealed melanoma. The tumor consisted of two different patterns, being composed partly of epithelioid cells and partly of spindle-shaped cells. Immunohistochemically the epithelioid cells showed a positive reaction for HMB-45 and NKI/C3, and a negative reaction for desmin and alpha-sarcomeric actin. The spindle-shaped cells showed a negative reaction for HMB-45 and NKI/C3, and a positive reaction for desmin and alpha-sarcomeric actin. Ultrastructurally the spindle-shaped cells had some schwannian features, namely, a basal lamina, interdigitating cell processes, and junctional complexes. The pathologic findings of our case suggest possible direct rhabdomyogenic differentiation of melanoma cells.

The role of glutamate in behavioral and neurotoxic effects of methamphetamine

Studies on the mechanisms of behavioral and neurochemical effects of amphetamine or methamphetamine (MA) have focused on the dopaminergic system. However, recent reports suggest that the glutamatergic system may be involved in the MA effects. Our laboratory has been conducting a series of experiments to further examine the role of glutamate in both behavioral and neurotoxic effects of MA. These studies include (1) behavioral studies on the effect of N-methyl-D-aspartate (NMDA) antagonists on the development of MA-induced behavioral sensitization, (2) neurochemical studies on the effects of NMDA antagonists on MA-induced neurotoxicity, and (3) in vivo microdialysis studies on the effects of MA on glutamate release. In the present paper, the authors comment on an important role of glutamatergic systems in the behavioral and toxic effects of MA.

Gastric lesions in 76 patients with adult T-cell leukemia/lymphoma. Endoscopic evaluation

BACKGROUND

Adult T-cell leukemia/lymphoma (ATLL) is caused by human T-lymphotropic virus type I. Gastric lesions in ATLL have not been described precisely, whereas the clinical features of ATLL have been well documented. The goal of the present study was to review gastric lesions, including gastric involvement, of patients with ATLL who were admitted to our hospital.

METHODS

Endoscopic examination of the upper gastrointestinal tract was performed on 76 of 110 patients who were admitted to our hospital between 1981 and 1994. Gastric involvement was diagnosed by histologic examination of biopsy specimens of gastric lesions. Types of gastric lesions, histologic features, and survival periods in patients with ATLL were summarized.

RESULTS

Of the 76 patients with ATLL who underwent an endoscopic examination, 23 had gastric involvement (30.3%). Twenty-seven patients had other gastric lesions: 10 with peptic ulcers (13.2%), 8 with gastric erosions (10.5%), 3 with submucosal tumors (3.9%), 2 with hyperplastic polyps (2.6%), 1 with gastric adenoma (1.3%), and 3 with gastric carcinomas (3.9%). The most frequent endoscopic configuration of gastric involvement with ATLL was the diffuse type with ulceration, and the most common histology was large cell type. Among those with the acute type ATLL, the survival period of those patients with gastric involvement was less than that of the patients without gastric involvement. In contrast, the survival period for lymphoma type ATLL did not differ among the groups regardless of gastric involvement.

CONCLUSIONS

This study demonstrated that 30.3% of patients with ATLL had gastric involvement and 13.2% had peptic ulcers. Gastric involvement of ATLL was one of the prognostic factors in acute type ATLL, whereas it had no influence on the prognosis of lymphoma type ATLL.

Occult intrasacral meningocele associated with spina bifida: a case report

We present a rare case of occult intrasacral meningocele associated with spina bifida and tethered cord syndrome in a 13-year-old female. The etiology is thought to be due to a dysraphic disorder. The pertinent literature is reviewed.

Effect of repeated methamphetamine pretreatment on freezing behavior induced by conditioned fear stress

The present study examined the effect of methamphetamine (MA) pretreatment on conditioned fear stress in male Wistar-King rats. Rats received MA or the vehicle according to the repeated escalating dose schedule (1.25, 2.5, 3.75, and 5 mg/kg s.c. x 2/every other day for a week). After a 5-day drug abstinent period, the rats were exposed to conditioned fear stress (exposure to an environment paired previously with foot shock). Repeated but not single MA pretreatment significantly increased conditioned freezing behavior, suggesting that rats previously exposed to chronic MA are hypersensitive to subsequent stress than control rats. Repeated MA treatment did not decrease basal dopamine or serotonin concentrations in the brain. Furthermore, coadministration of MK-801 (noncompetitive NMDA antagonist), amfonelic acid (dopamine reuptake inhibitor), or fluoxetine (serotonin reuptake inhibitor) with MA did not alter the enhanced freezing behavior. Taken together, it seems that MA-induced hypersensitivity to stress is not due to the neurotoxic effect of MA. Coadministration of nemonapride (D2/3/4 antagonist) with MA prevented the MA-induced increase in freezing. These results suggest that D2/3/4 receptors play an important role for MA-induced enhancement of fear or anxiety.

Survival of metabolically inhibited ventricular myocytes is enhanced by inhibition of rigor and SR Ca2+ cycling

During severe ATP depletion, sarcolemmal rupture resulting from rigor- and/or Ca(2+)-induced myofilament force development is considered to be an important cause of irreversible cell injury. Recent experiments in our laboratory demonstrated that during prolonged metabolic inhibition (MI) in adult rabbit ventricular myocytes, in which rigor was prevented by exposure to 30 mM 2,3-butanedione monoxime (BDM), cyclic uptake and release of cystolic Ca2+ occurred and was associated with strong phasic contractions. To investigate the relative contribution of this sarcoplasmic reticulum Ca2+ cycling and associated force development to energy depletion injury, the effects of BDM together with 7 mM caffeine were examined in isolated rabbit ventricular myocytes subjected to MI with 2 mM NaCN and 20 mM 2-deoxyglucose (2-DG). During 90 min of MI with CN and 2-DG, no cells retained a rod shape in the absence of BDM or caffeine. In the presence of both 30 mM BDM and 7 mM caffeine during MI, preservation of rod morphology was enhanced, and 52 +/- 6.2% of cells retained a rod shape 48 h after metabolic inhibition and had normal ATP content and resting membrane potential. Both systolic and diastolic functions of cells that survived MI, however, were impaired. We conclude that exposure to caffeine together with BDM markedly enhances survival of myocytes during severe prolonged ATP depletion. After recovery, these isolated myocytes show some characteristics of stunning.

Purification of anticoagulant factor from the spine venom of the crown-of-thorns starfish, Acanthaster planci

The fraction with anticoagulant activity was purified from the spine venom of Acanthaster planci by fractionation with ammonium sulfate followed by column chromatography and designated plancinin. Its molecular weight determined by tricine-SDS polyacrylamide gel electrophoresis was about 7500 in native form and about 3000 in reduced conditions. Plancinin showed neither platelet aggregation nor an enhancement of vascular permeability. Fibrin formation time was prolonged by 25 micrograms of plancinin which was comparable to 0.08 units of heparin. 2-Mercaptoethanol inhibited the anticoagulant activity of plancinin with a 50% inhibition concentration of 5.6 x 10(-3) M. The bleeding time of mice was significantly prolonged by i.v. administration of plancinin and this effect was lost when plancinin was given orally or s.c. These data indicate that plancinin is a peptide with disulfide bond which is essential for the anticoagulant activity.

Potentiation of the reversal activity of SDZ PSC833 on multi-drug resistance by an anti-P-glycoprotein monoclonal antibody MRK-16

SDZ PSC833 (PSC833), an analogue of cyclosporines, is one of the most potent modulators of multi-drug resistance (MDR). We previously reported that MRK-16, an anti-P-glycoprotein MAb, enhanced MDR reversal activity of cyclosporin A (CsA) through inhibition of P-glycoprotein-mediated CsA transport. We have examined here whether MRK-16 can enhance MDR reversal activity of PSC833. We found that MRK-16 potentiated the MDR reversal activity of PSC833, and of CsA, in MDR sublines of human myelocytic leukemia K562 and human ovarian cancer A2780 cells. Like MRK-16 combined with CsA, MRK-16 enhanced the effect of a sub-optimum dose of PSC833 on vincristine accumulation in MDR cells. However, MRK-16 could not increase cellular accumulation of PSC833 in MDR tumor cells, yet it could increase cellular accumulation of CsA. P-glycoprotein could not transport PSC833 but could transport CsA. Our results indicate that MRK-16 potentiates the MDR reversal activity of both PSC833 and CsA, yet also suggest that the molecular mechanism of the potentiation differs between the two substances.

Identification of significant residues in the substrate binding site of Bacillus stearothermophilus farnesyl diphosphate synthase

Farnesyl diphosphate synthases have been shown to possess seven highly conserved regions (I-VII) in their amino acid sequences [Koyama et al. (1993) J. Biochem. (Tokyo) 113, 355-363]. Site-directed mutants of farnesyl diphosphate synthase from Bacillus stearothermophilus were made to evaluate the roles of the conserved aspartic acids in region VI and lysines in regions I, V, and VI. The aspartate at position 224 was changed to alanine or glutamate (mutants designated as D224A and D224E, respectively); aspartates at positions 225 and 228 were changed to isoleucine and alanine (D225I, D228A); lysine at position 238 was changed to either alanine or arginine (K238A, K238R). The lysines at positions 47 and 183 were changed to isoleucine and alanine (K471, K183A), respectively. Kinetic analyses of the wild-type and mutant enzymes indicated that the mutagenesis of Asp-224 and Asp-225 resulted in a decrease of Kcat values of approximately 10(4)- to 10(5)-fold compared to the wild type. On the other hand, D228A showed a Kcat value approximately one-tenth of that of the wild type, and the k(m) value for isopentenyl diphosphate increased approximately 10-fold. Both K471 and K183A showed k(m) values for isopentenyl diphosphate 20-fold larger and kcat values 70-fold smaller than the wild type. These results suggest that the two conserved lysines in regions I and V contribute to the binding of isopentenyl diphosphate and that the first and the second aspartates in region VI are involved in catalytic function. Aspartate-228 is also important for the binding of isopentenyl diphosphate rather than for catalytic reaction.

[Surgical treatment of aortic valve endocarditis associated with aortic root aneurysm and abscess]

Between Jan. 1979 and Mar. 1996, aortic root abscess and aneurysm were encountered in 10 (34.5%) of the 29 patients who underwent surgical treatment for the aortic valve endocarditis ; native valve endocarditis (NVE) in 8 and prosthetic valve endocarditis (PVE) in 2. Noncoronary sinus was involved in 8 (80%) of 10 patients, left coronary sinus destructed in one, and more than one sinus were involved in one. All patients underwent aortic valve replacement after repair of abscess or aneurysm with suture closure in 5, and patch closure in 3, and its resection in one. Aortic root reconstruction using a valved conduit was required for the repair of aortico-ventricular discontinuity followed debridement of the abscess cavity of almost entire annulus in one PVE patient who consequentry died of LOS and sepsis. There was no operative or postoperative death in the other patients, however, one female patient suddenly died 24 months after surgery. She underwent direct suture closure of left coronary sinus aneurysm and aortic valve replacement with a small-sized prosthetic valve. Suture dehiscence of the orifice of the aneurysm developed immediately after surgery. It is concluded that patch closure of aortic root aneurysm or abscess is recommended so as to avoid narrowing of left ventricular outflow tract and recurrence of aneurysm formation even if its orifice proved to be small.

[Traumatic thoracic aortic rupture--diagnosis and surgical repair]

Fifteen cases of traumatic thoracic aortic rupture (TAR) were treated at St. Marianna University Hospital from December 1980 to July 1995. Causes of TAR were due to vehicle accidents in 14 patients and fall in one patient. On diagnosis, contrast-enhanced CT scan was routinely performed in the patients with blunt chest trauma associated with superior mediastinal widening, loss of the aortic knob or right shift of the trachea on the initial roentgenogram. When CT scan demonstrated specific signs for TAR, pseudoaneurysm formation and/or extravasation of the contrast dye, aortography was eliminated before operation. As a role, operation was performed on an emergency basis as soon as the diagnosis was confirmed. Four cases died due to intrapleural rupture before or immediately after thoracotomy. Nine (82%) of the 11 patients in whom operation was completed survived and are doing well. In one of the 4 patients who underwent operation with simple aortic cross-clamping; paraplegia developed after 30 minutes of spinal ischemia. Left heart bypass with the Bio-Pump without heparin or with an antithrombin agent, argatroban, was used in recent 6 patients. Use of left heart bypass with the Bio-Pump without anticoagulant or with argatroban appears to be promising as a safe adjunct in the repair of TAR, preventing fatal bleeding of other injured organs.

Effect of estriol on bone loss in postmenopausal Japanese women: a multicenter prospective open study

OBJECTIVES

To assess the effects of oral estriol on the bone mineral density (BMD) and bone metabolism in postmenopausal women.

METHODS

Seventy-five natural postmenopausal women with a BMD of more than 10% below the peak bone density were treated for 50 weeks with 2 mg/day estriol (E3) cyclically and 0.8 g/day of calcium lactate continuously. BMDs at L2-L4 were measured by dual energy X-ray absorptiometry (DXA).

RESULTS

The BMD increased 1.79% (p < 0.01 vs. pretreatment) after 50 weeks, accompanied with decrease of biochemical markers of bone turnover. With regard to climacteric symptoms, Kupperman's menopausal index improved (p < 0.01 vs. pretreatment) after 5 weeks of treatment. As to the incidence of adverse events genital bleeding was observed in only 8.0% of the subjects. Endometrial histology and cytology showed neither abnormalities nor hyperplasia during and after the treatment.

CONCLUSIONS

Estriol prevented postmenopausal bone loss and improved climacteric symptoms effectively with low incidence of genital bleeding.

[Long-term evaluation of radiographic changes following cervical anterior fusion with hydroxyapatite ceramic spacer]

Cervical anterior fusion with iliac bone crest has become a popular surgical technique for cervical spondylotic disease. Since about 10 years ago, we have substituted hydroxyapatite ceramic spacer for autologous graft because of postoperative painful hip syndrome. Fourteen patients who underwent cervical anterior fusion with ceramic spacer were evaluated by plain radiographs for over eight years postoperatively. In six among the fourteen patients plain films demonstrated minimal stenosis of intervertebral disc height, of which the ratio ranged from 15% to 28% (mean 22%). The increase in mobility of the adjacent segment after fusion was noted in ten of the fourteen patients, although the ratio ranged only between 12% and 24% (mean 18%). In none of all the patients did dynamic plain films show cervical instability such as slippage and swan neck deformity. It seems that anterior fusion with ceramic spacer is a useful and safe method for a cervical spondylotic disease.

Effects of nitric oxide synthesis inhibition on methamphetamine-induced dopaminergic and serotonergic neurotoxicity in the rat brain

We examined effects of nitric oxide (NO.) synthesis inhibition on methamphetamine (MA)-induced dopaminergic and serotonergic neurotoxicity. The toxic dose of MA (5 mg/kg, sc, x4) significantly decreased contents of dopamine (DA), dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA) in the striatum (ST), and significantly decreased contents of serotonin (5-HT) in the ST, nucleus accumbens (NA) and medial frontal contex (MFC). Coadministration with a NO. synthase inhibitor, N omega-nitro-L-arginine methyl ester (LNAME) (30 mg/kg, i.p., x2), reduced the MA-induced decreases in contents of DA, DOPAC and HVA in the ST, but not reduced the MA-induced decreases in contents of 5-HT in the ST, NA and MFC. These findings suggest that the MA-induced dopaminergic, but not serotonergic neurotoxicity, may be related to the neural process such as NO. formation caused by the activation of postsynaptic DA receptor.