[Expression of human endogenous retroviruses in rheumatoid arthritis]

The genomes of all organisms, from yeast to humans, contain thousands of endogenous retroviruses (ERVs) and ERVs are transmitted vertically through germ cells as provirus. In recent studies, it has been reported that some ERVs have important immunologic effects and are associated with autoimmune diseases in several animals. However, despite many years of investigation in human, physiological or pathological roles for ERVs remain unknown. In this study we examined whether the pathogenesis of rheumatoid arthritis (RA) was associated with human ERVs; ERV3 and lambda 4-1, which retain open reading frames (ORF) and could make proteins. We demonstrated that ERV3 and lambda 4-1 were expressed on synoviocytes and peripheral blood mononuclear cells (PBMCs) in RA patients by Northern blot analysis. But the expression was indeed heterogenous: RA patients showed various expression levels of ERV3 and lambda 4-1, which were independent of clinical activities and kinds of used drugs. mRNAs of ERV3 and lambda 4-1 were also expressed in PBMCs of healthy volunteers. We detected a 4.2 kb transcript of lambda 4-1 in synoviocytes and PBMCs which was not expressed in placentas, suggesting a unique protein might be produced in synoviocytes and PBMCs compared to placentas. In order to examine regulatory mechanisms for expression of human ERVs, we treated cultured synoviocytes and human kidney endothelial cells (hKEC) with various cytokines. By interleukin-1 beta (IL-1 beta) treatment, ERV3 expression in synoviocytes was not altered, but that in hKEC increased and correlated with IL-6 expression. Although ERV3 and lambda 4-1 expression may not be directly associated with the pathogenesis of RA, the possibility still exists that some of many ERVs, which are integrated into human genomes, may have causative roles in RA.

Structural diversity of band 4.1 superfamily members

Several proteins contain the domain homologous to the N-terminal half of band 4.1 protein, indicating the existence of a superfamily. The members of this ‘band 4.1’ superfamily are thought to play crucial roles in the regulation of cytoskeleton-plasma membrane interaction just beneath plasma membranes. We examined the structural diversity of this superfamily by means of the polymerase chain reaction using synthesized mixed primers. We thus identified many members of the band 4.1 superfamily that were expressed in mouse teratocarcinoma F9 cells and mouse brain tissue. In total, 15 cDNA clones were obtained; 8 were identical to the corresponding parts of cDNAs for the known members, while 7 appeared to encode novel proteins (NBL1-7: novel band 4.1-like proteins). Sequence analyses of these clones revealed that the band 4.1 superfamily can be subdivided into 5 gene families; band 4.1 protein, ERM (ezrin/radixin/moesin/merlin/NBL6/NBL7+ ++), talin, PTPH1 (PTPH1/PTPMEG/NBL1-3), and NBL4 (NBL4/NBL5) families. The NBL4 family was first identified here, and the full-length cDNA encoding NBL4 was cloned. The deduced amino acid sequence revealed a myristoylation site, as well as phosphorylation sites for A-kinase and tyrosine kinases in its N-terminal half, suggesting its involvement in the phosphorylation-dependent regulation of cellular events just beneath the plasma membrane. In this study, we describe the initial characterization of these new members and discuss the evolution of the band 4.1 superfamily.

Role of endogenous atrial natriuretic peptide on systemic and renal hemodynamics in heart failure rats

To investigate the role of endogenous atrial natriuretic peptide (ANP) in rats with heart failure (HF), we administered HS-142-1 (HS; 3 mg/kg body wt iv), a novel nonpeptide ANP-receptor antagonist, to rats with surgically induced myocardial infarction and sham-operated rats. HF was characterized by a higher left ventricular end-diastolic pressure and higher plasma ANP concentration vs. controls. HS administration significantly reduced the plasma and urinary levels of guanosine 3',5'-cyclic monophosphate in rats with HF [plasma concentration 10.6 +/- 2.6 vs. 2.7 +/- 0.4 nM (P < 0.05); urinary excretion 48 +/- 8 vs. 12 +/- 2 pmol/min (P < 0.05)]. Systemic and renal hemodynamics were unaffected by HS administration. Urine flow (-35%) and urinary sodium excretion (-50%) were significantly decreased after HS only in those rats with HF that had no changes in systemic and renal hemodynamics. These results suggest that the elevated ANP levels in HF do not contribute directly to the maintenance of systemic hemodynamics but rather compensate for the HF mainly via diuresis and natriuresis, achieved by the inhibition of renal tubular reabsorption rather than by renal vasodilatation.

Perturbation of cell adhesion and microvilli formation by antisense oligonucleotides to ERM family members

To examine the functions of ERM family members (ezrin, radixin, and moesin), mouse epithelial cells (MTD-1A cells) and thymoma cells (L5178Y), which coexpress all of them, were cultured in the presence of antisense phosphorothioate oligonucleotides (PONs) complementary to ERM sequences. Immunoblotting revealed that the antisense PONs selectively suppressed the expression of each member. Immunofluorescence microscopy of these ezrin, radixin, or moesin "single-suppressed" MTD-1A cells revealed that the ERM family members are colocalized at cell-cell adhesion sites, microvilli, and cleavage furrows, where actin filaments are densely associated with plasma membranes. The ezrin/radixin/moesin antisense PONs mixture induced the destruction of both cell-cell and cell-substrate adhesion, as well as the disappearance of microvilli. Ezrin or radixin antisense PONs individually affected the initial step of the formation of both cell-cell and cell-substrate adhesion, but did not affect the microvilli structures. In sharp contrast, moesin antisense PONs did not singly affect cell-cell and cell-substrate adhesion, whereas it partly affected the microvilli structures. These data indicate that ezrin and radixin can be functionally substituted, that moesin has some synergetic functional interaction with ezrin and radixin, and that these ERM family members are involved in cell-cell and cell-substrate adhesion, as well as microvilli formation.

Distribution of fluoride in the dental tissues and their supporting mandibular bone from the same individual

Dental and skeletal tissues have their own distinct fluoride distribution profiles. It was thought useful to compare these within individuals as normally comparisons are made between different groups of individuals. The average fluoride concentration decreased in the following order; cementum, alveolar bone, cancellous bone, mandible, dentine and enamel.

The role of capsaicin-sensitive sensory neurons in healing of HCl-induced gastric mucosal lesions in rats

BACKGROUND/AIMS

Capsaicin-sensitive sensory neurons are important in protecting the stomach against damage. This study investigated the role of these sensory neurons in the healing of gastric lesions.

METHODS

Rats fasted for 18 hours were given 1 mL of 0.6N HCl orally for induction of gastric lesions; they were then fed normally from 1 hour later. On various days after HCl treatment, the area of lesion, acid secretion, mucosal DNA synthesis, mucosal H+ permeability, and blood flow responses were measured.

RESULTS

Ablation of sensory neurons by capsaicin pretreatment did not affect the development of gastric lesions in response to HCl but significantly delayed the healing of these lesions. The damaged mucosa secreted less acid and had minimal changes in DNA synthesis but showed a marked increase in H+ permeability, resulting in luminal acid loss accompanied by an increase of mucosal blood flow. Sensory deafferentation did not have any influence on such changes in the damaged stomach, except the mucosal hyperemic response to acid.

CONCLUSIONS

Capsaicin-sensitive sensory neurons may contribute to the healing of gastric lesions by mediating the mucosal hyperemic responses associated with acid back-diffusion and by facilitating acid disposal in the mucosa.

The deleterious effects of exogenous angiotensin I and angiotensin II on myocardial ischemia-reperfusion injury

Angiotensin II is well known to have a cardiotoxic effects. However, it is still unclear whether exogenous angiotensin I or angiotensin II has a deleterious effect on myocardial ischemia-reperfusion injury. To examine this deleterious effects, we administered angiotensin I and angiotensin II to perfused hearts before ischemia, and measured creatine kinase (CK) release and cardiac function during subsequent reperfusion. Wistar Kyoto rats were used and the hearts were perfused by the Langendorff technique at a constant flow (10 ml/min). Seven hearts were perfused for 20 min and then subjected to 15 min of global ischemia (Control). In the experimental groups, during the 5 min before ischemia, we administered 100 ng/ml angiotensin I (Ang I; n = 9), 1 microgram/ml enalaprilat (ACEI; n = 5), both agents (ACEI + Ang I) (n = 6), or 10 ng/ml angiotensin II (Ang II; n = 6). The perfusates were then sampled to measure angiotensin II. After 15 min of ischemia, the hearts were reperfused with control perfusate. Throughout the 20 min of reperfusion, the effluent was collected to measure cumulative CK release. Angiotensin I increased coronary perfusion pressure (CPP) by 32 +/- 4 mmHg, however, the angiotension converting enzyme inhibitor inhibited the increase of CPP by angiotension I (11 +/- 1 mmHg) (p < 0.01). The contents of angiotensin II in the effluent in Ang I and Ang I + ACEI were 11.5 +/- 1.9 ng/ml and 4.0 +/- 0.5 ng/ml (p < 0.01). After 20 min of reperfusion, the left ventricular developed pressure was unchanged in all of the groups. CPP was also unchanged by ischemia in all of the groups.(ABSTRACT TRUNCATED AT 250 WORDS)

The effect of root conditioning with minocycline HCl in removing endotoxin from the roots of periodontally-involved teeth

Noting the acid-conditioning effect of minocycline on the root surface, we investigated the ability of minocycline to remove endotoxin on untreated, diseased cementum in vitro. Root surface specimens affected by periodontal disease were immersed in minocycline solution (10 mg/ml, 50 micrograms/ml, and 5 micrograms/ml) for 10 minutes, 1 day, 3 days, and 7 days, and endotoxin eluted was determined by the limulus amoebocyte lysate (LAL) assay. Specimens serving as controls were treated by immersion in pyrogen-free water, agitation, polishing, or exposure to citric acid (pH 1.0) for 3 minutes. When the period of immersion was the same, the root treatment with minocycline (10 mg/ml) yielded a significantly higher rate of neutralization of endotoxin than that with a 5 micrograms/ml or 50 micrograms/ml solution. However, the detoxifying effect of this method was less adequate than that of polishing or treatment with citric acid solution. There was variability in the effects of polishing among the teeth tested. To obtain the expected effect of the root treatment with minocycline solution; i.e., removal of the endotoxin, the combining of minocycline with a mechanical root preparation, such as polishing or root planing, seems to be effective.

Comparison of the effects of dobutamine and isoproterenol in ischemic hearts by phosphorus-31 nuclear magnetic resonance spectroscopy

We compared the effects of 2 inotropic agents, dobutamine and isoproterenol on regional coronary blood flow, contractile function, hemodynamics and levels of phosphate compounds in the acutely ischemic canine heart. Dogs were instrumented to determine regional coronary blood flow (non-radioactive microsphere method), contractile function (sonomicrometry), and hemodynamics. Myocardial phosphate compounds were measured simultaneously by the phosphate-31 (31P) magnetic resonance spectroscopic technique. Both drugs augmented the global performance of the heart, but produced no significant improvement in regional contractile function in the ischemic region. Isoproterenol significantly increased the ratio of inorganic phosphate to phosphocreatine in the ischemic region, as compared to dobutamine. However, no significant differences were seen in myocardial lactate consumption with inotropic stimulation between the 2 groups. 31P magnetic resonance spectroscopy could be used to differentiate between the effects of dobutamine and isoproterenol on energy metabolism in ischemic myocardium despite the lack of significant differences in regional function and myocardial lactate consumption. The significant tachycardia without an augmentation of systemic blood pressure induced by isoproterenol may account for this unfavorable effect on myocardial energy metabolism.

Expression of human nm23-H1 and nm23-H2 proteins in hepatocellular carcinoma

BACKGROUND

The expression of nm23-H1 and nm23-H2 proteins in 25 hepatocellular carcinomas was studied immunohistochemically.

METHODS

Tissue specimens were reacted with anti-human nm23-H1 and nm23-H2 monoclonal antibodies (MoAb) (H1-229 and H2-206, respectively) and then stained by the biotin-streptoavidin complex method.

RESULTS

Adjacent nontumorous tissues were intensely stained with nm23-H1 and nm23-H2. Of the 25 hepatocellular carcinomas, 60% were positive for MoAb H1-229, and 68% were positive for MoAb H2-206. These immunoreactivities were most common in the cytoplasm of tumor cells. There was no significant correlation between the expression of nm23-H1 protein and tumor size, Edmondson's histopathologic classification, or invasion of the capsule. However, the authors observed an inverse relationship between nm23-H1 expression and intrahepatic metastases of hepatocellular carcinomas. There was no significant correlation between the expression of nm23-H2 protein and clinicopathologic findings. Only a short survival period was observed in patients with hepatocellular carcinoma with reduced nm23-H1 or nm23-H2 proteins.

CONCLUSIONS

The results suggest that nm23-H1 protein plays a role in the suppression of intrahepatic metastasis of hepatocellular carcinoma and that the combined expression of nm23-H1 is associated with favorable prognosis.

Overexpression of p53 protein and proliferative activity in colorectal adenoma

Overexpression of p53 was studied immunohistochemically in colorectal tumors. We found p53-positive cells in 17 (58.6%) of 29 specimens of cancer in adenoma. Expression of p53 protein was detected in the nuclei of the tumor cells. We also found p53-positive cells in 7 (7.1%) of 99 specimens of adenoma. p53 immunoreactivity for severe dysplasia was higher than that for mild or moderate dysplasia. p53 expression in adenomas was restricted to a few glands, and the proliferating-cell nuclear antigen (PCNA)-positive rate for the p53-positive glands was significantly higher than that for p53-negative glands. The results suggested that the p53-positive glands might have high growth fractions, and that immunohistochemical detection of p53 expression in tubular adenomas might contribute to identifying the potential for malignant transformation.

Studies on pharmacological activation of human immunoglobulin G by chemical modification and active subfragments. XIII. Effect of carboxamidemethylated Fc fragment (CM-Fc) on type II collagen-induced arthritis in DBA/1J mice

The effect of carboxamidemethylated Fc fragment (CM-Fc) from human immunoglobulin G (IgG) on type II collagen (C II)-induced arthritis (CIA) in DBA/1J mice was studied. CM-Fc suppressed the development of CIA while Fc fragment did not. CM-Fc inhibited the increase in serum anti-C II IgG. CM-Fc suppressed C II-induced delayed type hypersensitivity (DTH) in DBA/1J mice. Moreover, the C II-induced proliferation of splenocytes from mice immunized with C II was suppressed by the administration of CM-Fc. Following an analysis of the lymphocyte population, a decreased percentage of B220+ cells and ratio of L3T4+/Ly-2+ cells was observed in lymph nodes of CM-Fc administered mice as compared with those of control group. These results suggest that CM-Fc inhibits CIA by regulating lymphocyte function.

Interleukin-8 gene expression in middle ear effusions

Interleukin-8 (IL-8), a monocyte- and macrophage-derived cytokine, displays potent chemotactic-activating properties toward neutrophils, and thus may contribute to the pathogenesis of otitis media with effusion (OME). The objective of this investigation was to demonstrate the expression of the IL-8 gene in middle ear effusion (MEEs) of children and adults with OME. Ribonucleic acids (RNAs) were extracted from MEEs from 16 ears of 13 pediatric patients and 12 ears of 12 adult patients with OME. The RNAs were reverse-transcribed and amplified by the polymerase chain reaction. Interleukin-8 transcripts were detected in 75% of both pediatric (12/16) and adult MEEs (9/12). The levels of expression of IL-8 and beta-actin messenger RNAs were quantitated. No significant difference was observed in IL-8/beta-actin ratios between pediatric MEEs and adult MEEs. These data suggest that IL-8 may contribute to neutrophil involvement in both pediatric and adult OME.

Hepatocellular carcinoma with splenic metastasis developing after 16 years of chemotherapy for chronic myelogenous leukemia: a case report

A case of hepatocellular carcinoma (HCC), which developed during chemotherapy for chronic myelogenous leukemia (CML), is presented. A 55-year-old Japanese man, who had received an alkylating agent for 16 years, was diagnosed as having HCC with clinically evident splenic metastases. The patient died of the HCC rupture three months after diagnosis. The autopsy revealed the HCC to have developed from the non-cirrhotic liver. In the present case, DNA damage due to the long-term chemotherapy with the alkylating agent for CML may have endowed the HCC induced by post-transfusion hepatitis and alcohol abuse with an aggressive proliferative potential. This is the first report on HCC in association with CML.

Application of a new morphometry system based on SEM stereo-pairs to the study of intestinal mucosa of rodents

A new morphometry system for submicroscopic three-dimensional structures was developed on the same principles as for the aerial survey using SEM stereo-pairs. This computer graphic system was applied to the analysis of the surface features of the intestinal mucosa. After removing the epithelial layer by prolonged osmication, core structures of the intestinal villi were exposed and 100 villi each from rat and mouse were measured. Average height, basal area and surface area of a single core of the rat were 188 microns, 20,200 microns2 and 93,500 microns2, respectively. Those of the mouse were 148 microns, 7,530 microns2 and 37,100 microns2, respectively. Surface amplifications by the rat and the mouse villi, after compensating for epithelial thickness, were calculated as 3.5 and 4.3, respectively; though amplifications based on the villous core were 4.6 and 4.9, respectively. These three-dimensional features of the intestinal mucosa were illustrated as submicroscopic maps by drawing their contour lines. It was demonstrated that the present morphometry system makes it possible to know not only the average features of a large sample, but also a variety of features of individual structures which were directly observed under SEM.

Methoxamine-induced release of endogenous ATP from rabbit pulmonary artery

Methoxamine, an alpha 1-adrenoceptor agonist, significantly increased the overflow of ATP, ADP and AMP, but not adenosine, by a prazosin-sensitive mechanism in the rabbit pulmonary artery. Among the adenine nucleotides released, the amount of ATP was larger than those of the other two. Such release of adenine nucleotides was not induced by clonidine, an alpha 2-adrenoceptor agonist, and isoproterenol, a beta-adrenoceptor agonist. Methoxamine-induced release was observed in the absence of extracellular calcium, but was not observed at a low temperature, 27 degrees C. This suggests an extracellular calcium-independent and temperature-dependent ATP-releasing mechanism coupled with alpha 1-adrenoceptors in rabbit pulmonary artery.

Two isoforms of the rat kidney EP3 receptor derived by alternative RNA splicing: intrarenal expression co-localization

Two different clones, named rEP3A (approximately 2.2 kb) and rEP3B (approximately 5.2 kb), were isolated from a rat kidney cDNA library by a homology screening approach. rEP3A was shown to encode the rat kidney prostaglandin E receptor EP3 subtype (rEP3A receptor) (Takeuchi, K. et al. B.B.R.C. (1993) 194: 885). rEP3B receptor differs only in its carboxyl-terminal tail (Ile-336 to Pro-364) from rEP3A receptor. Southern blot analysis of genomic DNA has suggested that the EP3 receptor gene is a single copy gene. RT-PCR using microdissected nephron segments showed co-expression of both receptor mRNAs specifically in distal nephron segments such as mTAL, cTAL, CCD and IMCD, whereas no significant expression of both receptor mRNAs was detected from GL, PCT, and PST. In conclusion, we have cloned an isoform of the rat kidney EP3 receptor, rEP3B receptor. rEP3A and rEP3B receptors are suggested to be derived by alternative RNA splicing, and both receptors are co-localized to distal tubules exerting an effect on water and electrolyte metabolism.

Intercellular adhesion induced by anti-alpha 3 integrin (VLA-3) antibodies

We generated four monoclonal antibodies (mAbs) specific for human alpha 3 integrin (VLA-3 alpha subunit). All of them were found to induce homotypic cell aggregation of HT1080 fibrosarcoma and SN12C renal carcinoma cells, both of which express high levels of alpha 3 integrin. The antibodies also induced the cell aggregation of K562 erythroleukemic cells transfected with alpha 3 integrin cDNA, but not the parental K562 cells. The aggregation was observed in a temperature-dependent manner and was not inhibited by the addition of EDTA. Immunofluorescence microscopic observation showed that alpha 3 integrin on HT1080 cells was translocated into the contact regions after the mAb treatment. The intercellular adhesion between cells expressing alpha 3 integrin and cells without alpha 3 integrin was also induced by the anti-alpha 3 antibody treatment.

Correlation of third ventricular enlargement and EEG slow wave activity in schizophrenic patients

Twenty-eight schizophrenic patients and 22 normal control subjects underwent magnetic resonance imaging (MRI) and topographic electroencephalography (EEG) in a study attempting to correlate morphological and electrophysiological findings. Schizophrenic patients had larger anterior horns of the lateral ventricles and third ventricles than normal control subjects. Schizophrenic patients showed more delta wave activity in the right parietooccipital region than normal control subjects. Alpha 2 wave activity was reduced in the entire region in schizophrenic patients. In schizophrenic patients, a significant positive correlation was seen between the area of the third ventricle and delta wave activity in the right occipital region. These results suggest that schizophrenic patients may have a dysfunction of diencephalic structures associated with morphological abnormality.

Developing of EEG print and its preliminary technical application

In this report, we discuss a method called "EEG print" to represent EEG contrast mapping in time and frequency domains simultaneously. A bank of bandpass FIR (Finite Impulse Response) digital filters is used to obtain EEG prints. EEG prints were taken from four areas (F3, F4, O1 and O2) of EEG when healthy subjects were at rest with their eyes closed. The pattern of the prints was classified into four types: alpha type, beta type, alpha + beta type and complex type. It was found that EEG prints may vary from person-to-person but they usually do not vary much between the four areas for a given person. The method is further modified to obtain "differential EEG prints" to investigate whether meaningful higher frequency EEG components exist. Differentiation of EEG resulted in marked intensification of the fast waves, using 0.14 Hz as the critical point. In differential EEG print with higher order differentiation, amplification in the high frequency components increase their frequency. As a result, it is possible to observe variations in the high frequency components, which are otherwise not detectable in the usual EEG print. EEG print can be used for representing the function of the brain. Using the method for classification of EEG print patterns, described in this paper, we can clarify not only the characteristics of the normal brain but also the pathophysiology of mentally-ill patients.

Induction of gastric lesions and hypoglycemic response by food deprivation in streptozotocin-diabetic rats

Overnight fasting causes hemorrhagic lesions in the stomach of streptozotocin (STZ)-induced diabetic rats, but the pathogenetic mechanism remains unknown. The present study was performed to investigate the pathogenesis of such lesions developed in STZ-diabetic rats after starvation, mainly in relation to blood glucose changes. A single injection of STZ (70 mg/kg, intraperitoneally) induced hyperglycemic conditions one week after the administration, and high blood glucose levels (BGL: > 350 mg%) remained up to three weeks later. The STZ-diabetic rats developed gastric lesions with the marked reduction of BGL after 18 hr of fasting, depending upon the duration of diabetes; the lesion score and delta BGL reduction in the 3-week-old STZ rats were 32.0 +/- 7.8 mm and > 250 mg/100 ml, respectively. Acid secretion in the pylorus-ligated rats was not significantly changed in the STZ-induced diabetic conditions for the initial two weeks but slightly decreased at three weeks when compared with normal rats. Fasting of normal rats for 18 hr did not cause either BGL reduction or any lesion in the stomach. In the 3-week-old STZ animals, the severity of gastric lesions increased with the duration of fasting (4-18 hr) and was again closely associated with the degree of delta BGL reduction. These lesions induced by 18 hr of starvation in 3-week-old STZ rats were significantly inhibited by pretreatment with insulin (4 units/rat/day) for the last one week to maintain BGL within normal ranges or by intravenous infusion of 25% glucose during fasting period. Both of these treatments significantly prevented BGL reduction in response to fasting.(ABSTRACT TRUNCATED AT 250 WORDS)

Influenza virus M2 protein ion channel activity stabilizes the native form of fowl plague virus hemagglutinin during intracellular transport

The influenza A/fowl plague virus/Rostock/34 hemagglutinin (HA), which is cleaved intracellularly and has a high pH threshold (pH 5.9) for undergoing its conformational change to the low-pH form, was expressed from cDNA in CV-1 and HeLa T4 cells in the absence of other influenza virus proteins. It was found, by biochemical assays, that the majority of the HA molecules were in a form indistinguishable from the low-pH form of HA. The acidotropic agent, ammonium chloride, stabilized the accumulation of HA in its native form. Coexpression of HA and the homotypic influenza virus M2 protein, which has ion channel activity, stabilized the accumulation of HA in its pH neutral (native) form, and the M2 protein ion channel blocker, amantadine, prevented the rescue of HA in its native form. These data provide direct evidence that the influenza virus M2 protein ion channel activity can affect the status of the conformational form of cleaved HA during intracellular transport.

Endogenous nitric oxide in gastric alkaline response in the rat stomach after damage

BACKGROUND/AIMS

The gastric mucosa responds to hypertonic NaCl by significantly decreasing acid secretion. This study examined the role of nitric oxide in this phenomenon.

METHODS

A rat stomach was mounted in an ex vivo chamber and perfused with saline; then the potential difference (PD), pH, and acid and/or alkaline responses were measured before and after the application of 1 mol/L NaCl with or without pretreatment with NG-nitro-L-arginine methyl ester (L-NAME), an inhibitor of NO biosynthesis.

RESULTS

A dose of 1 mol/L NaCl caused a reduction in PD, a decrease in basal and histamine-stimulated acid secretion, and an increase in luminal HCO3-. Prior administration of L-NAME did not affect either the PD or the HCO3- response but significantly attenuated the inhibitory effect of 1 mol/L NaCl on acid secretion. This effect of L-NAME was antagonized by the simultaneous administration with L-arginine but not D-arginine. Histamine-stimulated acid secretion in the normal stomach was significantly reduced by the exogenous NO donor nitroprusside but not by L-NAME.

CONCLUSIONS

NO is involved in the mechanism of the gastric alkaline response after damage with 1 mol/L NaCl. Irritation of the gastric mucosa by hypertonic NaCl may release endogenous NO, which in turn inhibits acid secretion and unmasks luminal alkalinization caused by HCO3- flux in the damaged portion.

Inhibition of the soluble and the tumor cell receptor-bound plasmin by urinary trypsin inhibitor and subsequent effects on tumor cell invasion and metastasis

The present study was undertaken to determine whether highly purified human urinary trypsin inhibitor (UTI) efficiently inhibits the soluble and the tumor cell receptor-bound plasmin. The ability of plasmin inhibitors to regulate invasion by tumor cells which express membrane-associated plasmin was also examined. UTI and two other plasmin inhibitors [alpha 2-anti-plasmin (alpha 2AP) and alpha 2-macroglobulin (alpha 2M)] were used. alpha 2AP and alpha 2M, as well as UTI, rapidly inactivate the soluble plasmin that is not bound to cells. Experiments were performed in vitro using cultures of ovarian cancer HOC-I cells and gestational choriocarcinoma SMT-ccl cells. HOC-I and SMT-ccl cells had plasmin(ogen) on their cell surface, and the plasmin activity was detected on their cell surface enzymologically and immunologically. Receptor-bound plasmin reacted effectively with UTI and was directly inactivated by UTI. In contrast, receptor-bound plasmin was not inhibited by alpha 2AP and alpha 2M. Using a modified Boyden chamber and an artificial basement membrane, Matrigel, it was found that UTI, but not alpha 2AP or alpha 2M, can inhibit HOC-I and SMT-ccl cells invasion in vitro. Furthermore, in the experimental lung metastasis model, UTI inhibited the formation of lung metastasis by Lewis lung carcinoma cells. The inhibition of tumor cell invasion was not due to direct antitumor effects of UTI. These results suggest that inhibition of receptor-bound plasmin by UTI is associated with significantly reduced tumor cell invasiveness in vitro and with a decreased number of metastasis in vivo.