Resistance of infant leukemia with MLL rearrangement to tumor necrosis factor-related apoptosis-inducing ligand: a possible mechanism for poor sensitivity to antitumor immunity.

Malignant cells generally acquire some immune escape mechanisms for clonal expansion. Immune escape mechanisms also contribute to the failure of graft-versus-leukemia (GVL) effect after allogeneic hematopoietic stem cell transplantation (allo-SCT). Infant leukemias with mixed-lineage leukemia (MLL) rearrangement have a remarkably short latency, and GVL effect after allo-SCT has not been clearly evidenced in these leukemias. Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL)- and FasL-mediated cytotoxic pathways play important roles in cytotoxic T-lymphocyte- and natural killer cell-mediated antitumor immunity and optimal GVL activity. We investigated the in vitro sensitivity of MLL-rearranged acute lymphoblastic leukemia (ALL) and acute myeloblastic leukemia (AML) cells to TRAIL- and FasL-mediated cytotoxicity. Most of cell lines and primary leukemia cells were highly resistant to TRAIL primarily owing to low cell-surface expression of death receptors in ALL and simultaneous expression of decoy receptors in AML. Nearly half of cell lines and majority of primary leukemia cells showed low sensitivity to FasL. These results suggest that resistance to death-inducing ligands, particularly to TRAIL, could be one of the mechanisms for a rapid clonal expansion and a poor sensitivity to the GVL effect in infant leukemias with MLL rearrangement.

Some investigations into non-passive listening.

Our knowledge of the function of the auditory nervous system is based upon a wealth of data obtained, for the most part, in anaesthetised animals. More recently, it has been generally acknowledged that factors such as attention profoundly modulate the activity of sensory systems and this can take place at many levels of processing. Imaging studies, in particular, have revealed the greater activation of auditory areas and areas outside of sensory processing areas when attending to a stimulus. We present here a brief review of the consequences of such non-passive listening and go on to describe some of the experiments we are conducting to investigate them. In imaging studies, using fMRI, we can demonstrate the activation of attention networks that are non-specific to the sensory modality as well as greater and different activation of the areas of the supra-temporal plane that includes primary and secondary auditory areas. The profuse descending connections of the auditory system seem likely to be part of the mechanisms subserving attention to sound. These are generally thought to be largely inactivated by anaesthesia. However, we have been able to demonstrate that even in an anaesthetised preparation, removing the descending control from the cortex leads to quite profound changes in the temporal patterns of activation by sounds in thalamus and inferior colliculus. Some of these effects seem to be specific to the ear of stimulation and affect interaural processing. To bridge these observations we are developing an awake behaving preparation involving freely moving animals in which it will be possible to investigate the effects of consciousness (by contrasting awake and anaesthetized), passive and active listening.

Early life stress induces sex-dependent increases in phosphorylated extracellular signal-regulated kinase in brains of mice with neuropathic pain.

BACKGROUND: Both early life stress and neuropathic pain induce morphological and functional abnormalities of the nervous system that are associated with emotional regulation. In our previous study, early life stress enhanced nerve injury-induced hyperalgesia in adult male and female mice. In the present study, using phosphorylated extracellular signal-regulated kinase (p-ERK) as a marker of neuronal activation, we examined the effect of early life stress on neuronal function following partial sciatic nerve ligation (PSL). METHODS: Early life stress was induced by maternal separation from 2 to 3 weeks of age and by social isolation after weaning (MSSI). Neuropathic pain was induced by PSL at 9 weeks of age, and p-ERK expression after light touch stimulation to the ipsilateral paw was measured using immunohistochemistry 1 week after nerve injury. RESULTS: Although MSSI increased p-ERK expression in the paraventricular nucleus (PVN) and amygdala of male mice, PSL did not affect p-ERK expression in control and MSSI mice. In female mice, increased p-ERK expression was observed in the medial prefrontal cortex (mPFC) and nucleus accumbens (NAc). Furthermore, p-ERK expression in the PVN and amygdala was increased in MSSI-PSL mice. CONCLUSIONS: The present data suggest that early life stress sex-dependently and site-specifically increases neuronal activity in the brain. In addition, increased neuronal activity in multiplebrain regions of mice subjected to early life stress may enhance hyperalgesia after nerve injury. WHAT DOES THIS STUDY ADD?: Maternal separation and social isolation (MSSI) increased p-ERK in the paraventricular nucleus (PVN) and amygdala of male mice. MSSI increased p-ERK in the medial prefrontal cortex and nucleus accumbens of female mice. Neuropathic pain increased p-ERK in the PVN and amygdala of female MSSI mice.

Lipopolysaccharide-induced increase in plasma nitrotyrosine concentrations in rats.

Since the production of peroxynitrite may contribute to the pathophysiology of endotoxemia or sepsis, the quantities of the produced peroxynitrite were evaluated in rats after lipopolysaccharide (LPS) treatment by measuring plasma nitrotyrosine concentrations with a new method. The intraperitoneal administration of LPS caused a persistent increase in plasma nitrotyrosine concentrations, which reached a maximum with 6-fold level of the base line (105 pmol ml-1) at 24 h and gradually declined to 3-fold level of the base line at 7 days. However, plasma concentrations of nitrite and nitrate peaked at 18 h, returning to base line within 48 h. The effect of LPS on the increase in plasma concentration of nitrotyrosine was dose-dependent and consistent with that of nitrite and nitrate concentrations. On the other hand, intravenous injection of nitrotyrosine revealed a rapid clearance with a plasma half-life of 1.67 h. These results indicate that the elevation of plasma nitrotyrosine concentrations may persist for more than a week after LPS treatment, and that the determination of plasma nitrotyrosine concentrations may be useful to detect the previous peroxynitrite-dependent oxidative damages.

Receiver operating characteristic analysis on fasting plasma glucose, HbA1c, and fructosamine on diabetes screening.

OBJECTIVE: To determine the efficacy of HbA1c and fructosamine as alternatives to fasting plasma glucose (FPG) for diabetes screening. RESEARCH DESIGN AND METHODS: Receiver operating characteristic (ROC) analysis was conducted on the above tests. Comparison among tests was based on the area under ROC curve of a test. World Health Organization criteria for classifying glucose tolerance status of the subjects was used. The study consisted of subjects (n = 583) who visited the clinic from September to October 1989 and all diabetic cases (n = 36) from November 1989 to March 1990, after excluding those less than 40 yr of age or with hypoglycemic therapies (469 were normal, 88 with impaired glucose tolerance ( IGT], and 62 with diabetes). RESULTS: Area under ROC curve of HbA1c was not different from that of FPG. Area under curve of fructosamine was significantly smaller than that of FPG. For all tests, overall efficacy of a test to detect IGT and diabetes was considerably diminished compared with detection of diabetes alone. CONCLUSIONS: The discriminating ability of HbA1c is almost the same as that of FPG, therefore HbA1c is a good alternative to FPG. Fructosamine is not suitable for diabetes screening.

The activation of supraspinal GPR40/FFA1 receptor signalling regulates the descending pain control system.

BACKGROUND AND PURPOSE: The ω-3 polyunsaturated fatty acids exert antinociceptive effects in inflammatory and neuropathic pain; however, the underlying mechanisms remain unclear. Docosahexaenoic acid-induced antinociception may be mediated by the orphan GPR40, now identified as the free fatty acid receptor 1 (FFA1 receptor). Here, we examined the involvement of supraspinal FFA1 receptor signalling in the regulation of inhibitory pain control systems consisting of serotonergic and noradrenergic neurons. EXPERIMENTAL APPROACH: Formalin-induced pain behaviours were measured in mice. Antinociception induced by FFA1 receptor agonists was examined by intrathecal injections of a catecholaminergic toxin, 5-HT lowering drug or these antagonists. The expression of FFA1 receptor protein and c-Fos was estimated by immunohistochemistry, and the levels of noradrenaline and 5-HT in the spinal cord were measured by LC-MS/MS. KEY RESULTS: FFA1 receptors colocalized with NeuN (a neuron marker) in the medulla oblongata and with tryptophan hydroxylase (TPH; a serotonergic neuron marker) and dopamine ß-hydroxylase (DBH; a noradrenergic neuron marker). A single i.c.v. injection of GW9508, a FFA1 receptor agonist, increased the number of c-Fos-positive cells and the number of neurons double-labelled for c-Fos and TPH and/or DBH. It decreased formalin-induced pain behaviour. This effect was inhibited by pretreatment with 6-hydroxydopamine, DL-p-chlorophenylalanine, yohimbine or WAY100635. Furthermore, GW9508 facilitated the release of noradrenaline and 5-HT in the spinal cord. In addition, GW1100, a FFA1 receptor antagonist, significantly increased formalin-induced pain-related behaviour. CONCLUSION AND IMPLICATIONS: Activation of the FFA1 receptor signalling pathway may play an important role in the regulation of the descending pain control system.

Effects of cigarette smoke on nitric oxide-induced increase in cyclic GMP in nerve terminals of rat cerebral cortex.

Since nitric oxide (NO) has been widely accepted as a novel neuromodulator, which activates soluble forms of guanylate cyclase to increase in guanosine 3':5'-cyclic monophosphate (cyclic GMP) levels, the effect of water-soluble substance in cigarette smoke on cyclic GMP levels were investigated using nerve terminals prepared from rat cerebral cortex. Although the smoke-substance itself failed to affect cyclic GMP levels in the synaptosomes, the smoke-substance significantly inhibited the increases in cyclic GMP levels induced by NO donors. The blocking effect of the smoke-substance was inhibited by concomitant incubation with superoxide dismutase, but not with mannitol. In addition, the effect of smoke-substance was mimicked by products of the xanthine/xanthine oxidase system, but not by nicotine. The effect of smoke-substance was preserved at least 7 days after they were stored at room temperature. Therefore, these results suggest that the smoke-substance may possess long half-lives to produce the radicals which inactivate NO, and to inhibit the increase in cyclic GMP levels in nerve terminals. The interference with NO may explain the part of mechanism in effects of cigarette smoke on neuronal functions.

Thirty-day operative mortality for thoracotomy in lung cancer.

OBJECTIVE: The 30-day operative mortality for thoracotomy in lung cancer is described herein. METHODS: From January 1994 through December 1994, the Japanese Association for Chest Surgery surveyed the number of thoracotomies for lung cancer by operative procedure, age, and operative mortality. The operative mortality was defined as death within 30 days of operation. RESULTS: The total number of operations was 7099. The overall 30-day operative mortality was 1.3%. By operative procedure, the mortalities were 3.2% for pneumonectomy, 1.2% for lobectomy, and 0.8% for a lesser operation, which showed a significant difference between pneumonectomy and lobectomy (p < 0.01). The mortality by age was 0.4% for patients younger than 60 years, 1.3% for those aged 60 to 69, 2.0% for those aged 70 to 79, and 2.2% for those aged 80 or older, which showed significant differences between the less than 60-year and 60- to 69-year-old groups, and between the 60- and 69-year-old and 70- and 79-year-old groups (p < 0.01 and p = 0.047, respectively). Pneumonia and respiratory failure caused most deaths (51.6%). CONCLUSIONS: The operative mortality in Japan for thoracotomy in lung cancer was satisfactorily low. The results of this study on a large population could serve as a standard when discussing the operative outcome of lung cancer.

Statistical survey of tracheobronchoplasty in Japan.

In a survey of 142 hospitals in Japan, 1562 operations involving tracheobronchoplasty, 565 involving tracheoplasty, and 992 involving bronchoplasty were found to have been done from 1954 to 1984. The number of operations showed a steep increase from 1965 and reached more than 200 a year by 1984. This increase comes from larger numbers of bronchoplasty procedures being performed for lung cancer (58.8% in toto) and of tracheoplasty procedures for thyroid cancer (9.7% in toto). Fifty-seven operative modes could be classified, in which bronchial anastomosis was most frequent (62.1%), followed in order by tracheal anastomosis (18.0%), and tracheobronchial anastomosis (5.9%). Complications, encountered in 16.9% in toto, resulted in death in 22.3%, with fistula bleeding in all and anastomotic stricture in 47.7%. Anastomotic stricture alone had a higher mortality rate than anastomotic stricture combined with recurrent palsy (p less than 0.01). The tracheal anastomosis mode had a higher complication rate than that of the bronchial anastomosis mode (p less than 0.01). Among the 57 modes, the complication rates were lower than those of each stem mode in the following: suture of the tracheal wall (p less than 0.05), tracheal patch grafting (p less than 0.01), sleeve resection of the right main bronchus (p less than 0.02), and sleeve lobectomy of the right lower lobe (p less than 0.001). Complication rates were higher than those of each stem mode in these procedures: prosthetic replacement of the trachea (p less than 0.001), sleeve resection of the right main bronchus (p less than 0.05), and the montage-type carinal reconstruction (p less than 0.05) modes. The tracheal anastomosis mode was classified into two categories, standard and extensive. The latter showed complication rates higher than the former (p less than 0.01), tracheoplasty (p less than 0.0025), and the tracheal anastomosis stem mode (p less than 0.0025). Complication rates have decreased with time, being 21.8% with the tracheal anastomosis mode and 10.8% with the bronchial anastomosis mode in the past 9 years.

Preoperative diagnosis with video-assisted thoracoscopy with miniaturized endoscopes in general thoracic surgery: a preliminary study.

Video-assisted thoracoscopy using a miniaturized endoscope (mini-VAT) was applied for preoperative diagnosis in general thoracic surgery. Thirty-one patients, including 27 with indeterminate pulmonary nodule and 4 with suspected pleural involvement of lung cancer or metastatic pleural tumor, underwent mini-VAT. As a pilot study, 14 of the former 27 patients underwent mini-VAT while receiving general anesthesia. As a prospective study, all the remaining 17 patients underwent mini-VAT while receiving local anesthesia. Solid scopes of three different sizes, 0.9, 1.9, or 4.0 mm diameter, were used. An artificial pneumothorax for scope introduction was produced by needle thoracentesis under atmospheric pressure. Automatic cutting needle biopsy was used for tissue sampling. In the pilot study group, mini-VAT with a 4.0-mm scope provided excellent visibility and diagnostic sensitivity of 100%. This study group showed the diagnostic sensitivity of needle biopsy for pulmonary nodule to be 100%. Hemorrhages and air leaks at biopsy sites were sealed with blood coagulation in a short time. In the prospective study group, mini-VAT with a 4.0-mm scope with the patients receiving local anesthesia provided a diagnostic sensitivity of 91% for pulmonary nodule and a diagnostic accuracy of 100% for suspected pleural involvement. Causes of failure of mini-VAT with the use of local anesthesia were cough reflex during needle biopsy and incomplete lung collapse for deeply located target in two cases. The adverse effects of the mini-VAT were paradoxical respiration in two cases in which local anesthesia was used. The patients who received only local anesthesia required no chest tube drainage. Mini-VAT is a simple, minimally invasive procedure suitable as a preoperative examination technique for histologic diagnosis, evaluation of disease progression, and selection of strategy in thoracic surgery.

The effect of ischemic time and temperature on lung preservation in a simple ex vivo rabbit model used for functional assessment.

Despite 25 years of research in lung transplantation, little progress has been made in methods for improving lung preservation. To evaluate many factors that may affect lung function after preservation, we have developed a simple, reliable, and inexpensive animal model. This consists of an isolated rabbit lung preparation perfused with blood and ventilated with a closed-circuit system. Heart-lung blocks were harvested and the left lung was assessed after ligation of the right pulmonary artery and right main-stem bronchus. On completion of a storage period, the left lung was ventilated and perfused with fresh rabbit venous blood at a rate of 40 ml/min for 10 minutes. Assessment of lung function included gas analysis of infused and effluent blood, oxygen uptake, mean pulmonary artery perfusion pressure, and mean airway pressure. A control group and six preservation groups were evaluated, each with different storage temperatures (38 degrees C, 34 degrees C, 23 degrees C, 15 degrees C, 10 degrees C, and 4 degrees C). For each temperature, ischemic periods ranging from 1 to 30 hours were studied. In the control group, the lungs were assessed immediately after being harvested. In the preservation groups, the lungs were kept partially inflated, stored at a predetermined temperature by immersion, and later assessed after variable ischemic periods. Our studies demonstrated the following: (1) The degree of impaired lung function produced by ischemia is reflected by a decrease in oxygen uptake and in oxygen tension of the effluent pulmonary venous blood and an increase in pulmonary artery perfusion pressure; (2) hypothermia improves ischemic tolerance; (3) preservation of lung at 10 degrees C is superior to preservation at 15 degrees C and 4 degrees C. This screening model has allowed evaluation of independent multiple factors and methods pertinent to lung preservation and enables one to assess lung function reliably and rapidly.

Loss of heterozygosity of the retinoblastoma gene in liver cirrhosis accompanying hepatocellular carcinoma.

Carcinogenesis is a multistep process. Most hepatocellular carcinoma (HCC) is preceded by liver cirrhosis, but the genetic changes involved in cirrhosis are not known well. The present study was conducted to evaluate aberration of the retinoblastoma (RB) gene in HCC and adjacent non-tumorous liver using 22 patients with chronic liver damage accompanying HCC. The specimens obtained by microdissection from paraffin-embedded tissues were analyzed using an assay based on the polymerase chain reaction for highly polymorphic nucleotide sequences of microsatellites in the RB gene. Out of 22 cases, 15 showed constitutional heterozygosity for the microsatellite markers. In 11 (73.3%) of these 15 informative cases, the primary HCC foci showed loss of heterozygosity (LOH). In 8 of these 11 doubly informative (informative and LOH-positive in primary HCC) cases, LOH was found in 20 (64.5%) of 31 microdissected non-tumorous foci. All of the non-tumorous foci showing RB loss were cirrhotic lesions but there were no foci of chronic hepatitis. The remaining 4 cases without LOH in HCC foci showed no LOH in non-tumorous lesions. In our study, LOH of the RB gene was frequently observed in liver cirrhosis surrounding tumor.

Frequent loss in chromosome 8p loci in liver cirrhosis accompanying hepatocellular carcinoma.

Most hepatocellular carcinoma (HCC) is preceded by liver cirrhosis, but the genetic changes involved in cirrhosis are not well understood. We therefore studied loss of heterozygosity (LOH) in cirrhotic and neoplastic foci in livers of 14 patients with HCC. The samples, microdissected from paraffin-embedded tissues, were analyzed using a polymerase-chain-reaction-based assay for dinucleotide repeat polymorphisms on 8p. Of the 14 cases, 13 showed constitutional heterozygosity for the microsatellite markers. In 7 (54%) of these 13 informative cases, LOH was detected in the primary HCC and, in these 7 doubly informative (informative and LOH-positive in primary HCC) cases, LOH was found in 16 (70%) of 23 liver cirrhotic foci. The pattern of 8p allelic loss was identical in each doubly informative tumor; however, some of the liver cirrhotic foci harbored an 8p loss identical to that seen in the primary HCC, some harbored a different 8p loss, and some did not harbor any 8p loss. The remaining 6 cases without LOH on 8p in HCC showed no 8p loss in any cirrhotic foci. Presumably HCC could develop from cirrhotic cells harboring 8p loss.

Operative approaches for left-sided carinoplasty.

Carinoplasty was performed in 42 patients: 7 with wedge pneumonectomy, 15 with sleeve pneumonectomy, 14 with one-stoma-type carinal reconstruction, 5 with montage-type carinal reconstruction, and 1 other. Diagnoses in the 42 patients consisted of lung cancer in 31 (73.8%), tuberculous stenosis in 10 (23.8%), and tracheobronchial injury in 1 (2.4%). The thoracotomy was on the right side for lung cancer in 77.4% and on the left side for tuberculous stenosis in 80.0% (p < 0.01). Left-sided carinoplasty was performed in 14 patients using four approaches: midline thoracotomy in 1, left thoracotomy in 10, midline sternotomy and left thoracotomy in 2, and bilateral thoracotomies in 1. Left wedge or sleeve pneumonectomy, without right thoracotomy, could be done by midline sternotomy and left thoracotomy but with limited tracheal resection. Left one-stoma-type carinoplasty was undertaken, sacrificing one lobe, as an alternative to pneumonectomy, where an approach drawing the carina down to an aortopulmonary window was considered to be preferable to the drawing-up approach.

A study on optimal temperature for isolated lung preservation.

Fifty-two heart-lung blocks (grafts) of New Zealand white rabbits were used for determining optimal temperature in lung preservation. Grafts were inflated with room air and preserved by simple surface cooling at arbitrarily determined temperatures for 18 hours. Graft function was assessed by nonrecirculated perfusion with autologous blood. Segmented regression models between functional parameters and preservation temperature (T) were applied for determining optimal temperature. Graft ability was also assessed from the point of view of pulmonary circulation by indocyanine green dilution rate of effluent and histological distribution of carbon particles. Significant segmented regression curves and lines between parameters of effluent oxygen tension (PO2) and wet-dry weight ratio (W/D), and T were obtained as follows: PO2 = 150/(1 + 3208.1[e-1.17T]), p less than 0.01; PO2 = -13.8T + 222.6, p less than 0.05; W/D = 5.0 + 1.5/(1 + 0.0028[e0.94T]), p less than 0.01; W/D = 0.075T + 4.52, p less than 0.05. Optimal temperature for lung preservation by topical cooling was calculated as 8 degrees to 9 degrees C from each intersecting point of regression equations. Analysis of regression curves suggested that the most common hypothermic ischemic injury during preservation by topical cooling is pulmonary vascular obstruction, which might be induced at temperatures lower than the critical temperature of 6 degrees to 7 degrees C. Indocyanine green dilution rate and histological findings supported the results of graft functional parameters.

Ansa-recurrent nerve anastomosis for vocal cord paralysis due to mediastinal lesions.

Recurrent laryngeal or vagus nerve injuries in the mediastinum are repaired rarely because of technical difficulties. Impairment in phonation is especially severe in patients with respiratory dysfunction. We performed a simple and less invasive reconstruction, ansa cervicalis-recurrent laryngeal nerve anastomosis in the neck, to improve phonation in 2 patients. Although the reinnervated vocal cord did not regain normal movement, both of the patients obtained excellent improvement in phonation.

Influence of temperature of flushing solution on lung preservation.

For lung transplantation the technique of flushing the donor pulmonary vascular bed may provide advantages in lung preservation such as rapid cooling and washout of blood. However, rapid cooling of the ischemic lung may also produce adverse effects. The aim of this study was to compare methods of cold flushing and topical cooling, and to evaluate the effect of temperature of the flushing solution on lung preservation. A total of 25 rabbit lungs were studied. Using an ex vivo rabbit lung model, postischemic function was assessed by the ability of the lung to oxygenate perfused blood and by measurement of pulmonary artery and airway pressures. The lungs in group I were preserved with simple immersion at 10 degrees C for 30 hours. The lungs in groups II through V were flushed with solution containing phosphate-buffered dextran (LPD) at different temperatures (groups II and IV, 10 degrees C; groups III and V, 23 degrees C) and stored at 10 degrees C for various ischemic periods (groups II and III, 30 hours; groups IV and V, 36 hours). Pulmonary vascular resistance during flushing at 10 degrees C was significantly higher than that at 23 degrees C (p < 0.001). Flushing resulted in better preservation than topical hypothermia. Flushing at 23 degrees C resulted in superior postischemic function compared with flushing at 10 degrees C. We conclude that in lung preservation, uniform flushing with LPD solution improves the ischemic tolerance as compared with topical hypothermia, and that flushing with solutions at too low temperatures may have adverse effects on lung preservation.

Effect of cystathionine as a scavenger of superoxide generated from human leukocytes or derived from xanthine oxidase in vitro.

We studied the direct effects of cystathionine on human leukocyte-generated or xanthine-xanthine oxidase-derived superoxide radicals in vitro. Washed leukocyte suspensions (10(6) cells/ml) prepared from healthy male volunteers were stimulated with phorbol myristate acetate (1 mu M) or opsonized zymosan (1 mg/ml) to generate superoxide radicals, which were measured with a 2-methyl-6-[p-methoxyphenyl]-3,7-dihydroimidazo[1,2-alpha] pyrazin-3-one hydrochloride (MCLA)-chemiluminescence method. Cystathionine (30 mu M to 10 mM) significantly reduced superoxide radical-dependent chemiluminescence in the leukocyte system in a concentration-dependent manner. In addition, in the two different methods of determination of superoxide radicals (MCLA chemiluminescence and nitroblue tetrazolium reduction), cystathionine significantly scavenged the superoxide radicals derived from the xanthine-xanthine oxidase system. However, cystathionine did not inhibit the activity of xanthine oxidase during superoxide generation. On the other hand, cystathionine did not show a scavenging effect against hydroxyl radicals derived from Fe2+ -H2O2 on the erythrocyte membrane. These results indicate that cystathionine itself may possess a scavenging function against superoxide radicals rather than against hydroxyl radicals in vitro.

Protective effect of cystathionine on acute gastric mucosal injury induced by ischemia-reperfusion in rats.

We studied the protective effect of cystathionine on acute gastric mucosal injury induced by ischemia-reperfusion in rats. Under pentobarbital anesthesia, the celiac artery was clamped for 30 min and reperfused. Sixty minutes after the reperfusion, the total area of erosions and thiobarbituric acid-reactive substances in the stomach, as an index of lipid peroxidation, were measured and compared between control and cystathionine-treated groups. Intraperitoneal administration of cystathionine (1-20 mg/kg) 10 min before the ischemia significantly reduced both the total area of erosions and the level of thiobarbituric acid-reactive substances. When cystathionine (10 mg/kg) was administered orally, the significant reductions in the total area of erosions and level of thiobarbituric acid-reactive substances were also observed. There was a good correlation between the total area of erosions and the level of thiobarbituric acid-reactive substances. Cystathionine did not affect blood flow during ischemia-reperfusion. These results indicate that the protective effect of cystathionine on acute gastric mucosal injury induced by ischemia-reperfusion may be due to the scavenging action against superoxide radicals in vivo.

Nitric oxide inhibition of the depolarization-evoked glutamate release from synaptosomes of rat cerebellum.

Effects of nitric oxide (NO) on release of amino acid transmitter were investigated by superfusion of synaptosomes prepared from rat cerebellum. After constant basal levels of amino acid release were obtained, exposure to a depolarizing concentration of KCl (30 mM) evoked 4.05-, 2.18- and 3.00-fold increases in release of glutamic acid (Glu), aspartic acid (Asp) and gamma-aminobutyric acid (GABA) from synaptosomes. The perfusion with NO-donors inhibited the evoked increases in release of Glu and Asp in a concentration-dependent manner, but not that in GABA release. A membrane-permeable analog of cyclic GMP, but not that of cyclic AMP, caused a similar reduction in the evoked release. The concentration of nitroprusside to increase cyclic GMP levels corresponded to that of nitroprusside to reduce the evoked release. These data suggest that NO may directly act upon the nerve terminals to inhibit release of excitatory amino acid transmitters.