Biomedical subjects

T Yamaguchi

Publications and source records attributed to T Yamaguchi.

At least 181 records · Page 10Linked to original sources

PubMed2001

Suppression of high-pressure-induced hemolysis of human erythrocytes by preincubation at 49 degrees C.

When human erythrocytes were preincubated at 37-52 degrees C under atmospheric pressure before exposure to a pressure of 200 MPa at 37 degrees C, the value of hemolysis was constant (about 43%) up to 45 degrees C but became minimal at 49 degrees C. The results from anti-spectrin antibody-entrapped red ghosts, spectrin-free vesicles, and N-(1-pyrenyl)iodoacetamide-labeled ghosts suggest that the denaturation of spectrin is associated with such behavior of hemolysis at 49 degrees C. The vesicles released at 200 MPa by 49 degrees C-preincubated erythrocytes were smaller than those released by the treatment at 49 degrees C or 200 MPa alone. The size of vesicles released at 200 MPa was independent of preincubation temperature up to 45 degrees C, and the vesicles released from 49 degrees C-preincubated erythrocytes became smaller with increasing pressure up to 200 MPa. Thus, hemolysis and vesiculation under high pressure are greatly affected by the conformation of spectrin before compression. Since spectrin remains intact up to 45 degrees C, the compression of erythrocytes at 200 MPa induces structural changes of spectrin followed by the release of large vesicles and hemolysis. On the other hand, in erythrocytes that are undergoing vesiculation due to spectrin denaturation at 49 degrees C, compression produces smaller vesicles, so that the hemolysis is suppressed.

Air Pressure↗

PubMed2001

Mechanism of chitosanase-oligosaccharide interaction: subsite structure of Streptomyces sp. N174 chitosanase and the role of Asp57 carboxylate.

We have investigated the mechanism of the interaction of Streptomyces sp. N174 chitosanase with glucosamine hexasaccharide [(GlcN)(6)] by site-directed mutagenesis, thermal unfolding, and (GlcN)(6) digestion experiments, followed by theoretical calculations. From the energy-minimized model of the chitosanase-(GlcN)(6) complex structure (Marcotte et al., 1996), Asp57, which is present in all known chitosanases, was proposed to be one of the amino acid residues that interacts with the oligosaccharide substrate. The chitosanase gene was mutated at Asp57 to Asn (D57N) and Ala (D57A), and the relative activities of the mutated chitosanases were found to be 72 and 0.5% of that of the wild type, respectively. The increase in the transition temperature of thermal unfolding (T(m)), usually observed upon the addition of (GlcN)(n) to chitosanase mutants unaffected in terms of substrate binding, was considerably suppressed in the D57A mutant. These data suggest that Asp57 is important for substrate binding. The experimental time-courses of [(GlcN)(6)] degradation were analyzed by a theoretical model in order to obtain the binding free energy values of the individual subsites of the chitosanases. A (-3, -2, -1, +1, +2, +3) subsite model agreed best with the experimental data. This analysis also indicated that the mutation of Asp57 affects substrate affinity at subsite (-2), suggesting that Asp57 most likely participates in the substrate binding at this subsite.

Acetylglucosamine↗

PubMed2001

Genes encoding the vacuolar Na+/H+ exchanger and flower coloration.

Vacuolar pH plays an important role in flower coloration: an increase in the vacuolar pH causes blueing of flower color. In the Japanese morning glory (Ipomoea nil or Pharbitis nil), a shift from reddish-purple buds to blue open flowers correlates with an increase in the vacuolar pH. We describe details of the characterization of a mutant that carries a recessive mutation in the Purple (Pr) gene encoding a vacuolar Na+/H+ exchanger termed InNHX1. The genome of I. nil carries one copy of the Pr (or InNHX1) gene and its pseudogene, and it showed functional complementation to the yeast nhx1 mutation. The mutant of I. nil, called purple (pr), showed a partial increase in the vacuolar pH during flower-opening and its reddish-purple buds change into purple open flowers. The vacuolar pH in the purple open flowers of the mutant was significantly lower than that in the blue open flowers. The InNHX1 gene is most abundantly expressed in the petals at around 12 h before flower-opening, accompanying the increase in the vacuolar pH for the blue flower coloration. No such massive expression was observed in the petunia flowers. Since the NHX1 genes that promote the transport of Na+ into the vacuoles have been regarded to be involved in salt tolerance by accumulating Na+ in the vacuoles, we can add a new biological role for blue flower coloration in the Japanese morning glory by the vacuolar alkalization.

Biological Transport↗

PubMed2001

The analgesic interaction between intrathecal clonidine and glutamate receptor antagonists on thermal and formalin-induced pain in rats.

UNLABELLED: Clonidine, an alpha(2) adrenergic receptor agonist, inhibits glutamate release from the spinal cord. We studied the interaction of intrathecally administered clonidine and glutamate receptor antagonists on acute thermal or formalin induced nociception. Sprague-Dawley rats with lumbar intrathecal catheters were tested for their tail withdrawal response by the tail flick test and paw flinches produced by formalin injection after intrathecal administration of saline, clonidine, AP-5 (a N-methyl-D-aspartate receptor antagonist), or YM872 (an alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid receptor antagonist). The combinations of clonidine and the other two agents were also tested by isobolographic analyses. Motor disturbance and behavioral changes were observed as side effects. The ED(50) values of clonidine decreased from 0.26 microg (tail flick), 0.12 microg (Phase 1) and 0.13 microg (Phase 2) to 0.036 microg, 0.006 microg, and 0.013 microg with AP-5, and 0.039 microg, 0.057 microg, and 0.133 microg with YM872, respectively. Side effects were attenuated in both combinations. In conclusion, spinally administered clonidine and AP-5 or YM872 exhibited potent synergistic analgesia on acute thermal and formalin-induced nociception with decreased side effects in rats. IMPLICATIONS: Combinations of a spinally administered alpha(2) adrenergic receptor agonist and an a N-methyl-D-aspartate receptor antagonist or an alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid receptor antagonist exhibited potent synergistic analgesia in acute thermal and inflammatory-induced nociception with decreased side effects.

Adrenergic alpha-Agonists↗

PubMed2001

Serial changes in cerebral blood flow and flow-metabolism uncoupling in primates with acute thromboembolic stroke.

The authors recently developed a primate thromboembolic stroke model. To characterize the primate model, the authors determined serial changes in cerebral blood flow (CBF) and the relation between CBF and cerebral metabolic rate of glucose (CMRglc) using high-resolution positron emission tomography. Thromboembolic stroke was produced in male cynomolgus monkeys (n = 4). Acute obstruction of the left middle cerebral artery was achieved by injecting an autologous blood clot into the left internal carotid artery. Cerebral blood flow was measured with [15O]H2O before and 1, 2, 4, 6, and 24 hours after embolization. CMRglc was measured with 2-[18F]fluoro-2-deoxy-D-glucose ([18F]FDG) 24 hours after embolization. Lesion size and location 24 hours after embolization was determined by the 2,3,5-triphenyltetrazolium chloride (TTC) staining method. The results are summarized as follows: (1) 1 hour after embolization, CBF in the temporal cortex and the basal ganglia decreased to < 40% of the contralateral values. In these regions, regarded as an ischemic core, CBF decreased further with time and CMRglc at 24 hours also decreased. Infarcted lesions as indicated by being unstained with TTC were consistently observed in these regions. (2) In the parietal cortex and several regions surrounding the ischemic core, CBF was > 40% of the contralateral values 1 hour after embolization and recovered gradually with time (ischemic penumbra). In these regions, CMRglc at 24 hours increased compared with that in the contralateral regions, indicating an uncoupling of CBF and CMRglc. No obvious TTC-unstained lesions were detected in these regions. The authors demonstrated a gradual recovery of reduced CBF, an elevated CMRglc and a CBF-CMRglc uncoupling in the penumbra regions of the primate model. Positron emission tomography investigations using this model will provide better understanding of the pathophysiology of thromboembolic stroke in humans.

Acute Disease↗

PubMed2001

Pleuropericarditis and disseminated intravascular coagulation in ulcerative colitis.

We report a 30-year-old woman with pleuropericarditis, cardiac tamponade, and disseminated intravascular coagulation complicating active ulcerative colitis (UC). Other autoimmune diseases were not present. She responded to pulsed steroid therapy and anticoagulant with resolution of the complication and UC. We reviewed the literature and found 27 cases of pleuropericarditis associated with idiopathic inflammatory bowel disease (IBD). It has been reported that pleuropericarditis associated with IBD responds well to nonsteroidal antiinflammatory drugs, as well as steroids. The causes of cardiac involvement in IBD remain unclear, but the pleuropericarditis must be recognized as a potential extraintestinal manifestation of IBD.

Adult↗

PubMed2001

Role of TGF-beta1, extracellular matrix, and matrix metalloproteinase in the healing process of the pancreas after induction of acute necrotizing pancreatitis using arginine in rats.

INTRODUCTION: Pancreatic tissues are almost completely restored to normal after an attack of acute pancreatitis, once the cause of the disease is removed. Transforming growth factor (TGF)-beta and extracellular matrix (ECM) are known to play an important role in the process of wound healing in pathologic diseases. Tissue repair is a process regulated by a balance between synthesis and degradation of ECM. AIMS: To elucidate the role of TGF-beta, ECM, and matrix metalloproteinase (MMP) in the process of regeneration occurring after acute necrotizing pancreatitis. METHODOLOGY: Acute necrotizing pancreatitis was induced by intraperitoneal injection of 500 mg/100 g body weight of L-arginine in male Wistar rats. Expression of TGF-beta1 and ECM messenger RNA (mRNA) was determined by Northern blot analysis, and that of MMP-1 and MMP-2 mRNA was examined by the reverse transcription polymerase chain reaction (RT-PCR). Immunoreactivity for ECM components, TGF-beta1, and MMP-2 in the pancreas was assessed by using a monoclonal antibody. RESULTS: TGF-beta1 mRNA expression reached a peak value on day 2.5, with a decrease on day 3, and reached the control level on day 7. Procollagen types III and IV and fibronectin mRNA reached a peak value on day 2.5, whereas the expression level of procollagen type I mRNA was maximal on day 3, and gradually decreased to control levels by day 7. MMP-2 mRNA was significantly elevated on day 3, and peaked on day 5, whereas MMP-1 mRNA levels did not change throughout the observation period. Immunoreactivity for MMP-2 was observed around disrupted acinar cells and interstitial spaces on day 3, and maximally on day 7. Immunoreactivity for fibronectin was detected around disrupted acinar cells and interstitial spaces. On day 7, it was less than on day 5 around disrupted acinar cells and interstitial spaces, whereas in the regenerated acinar cells, it was undetected. CONCLUSION: Our results show that TGF-beta1 mRNA expression peaked earlier than that of ECM mRNA. Furthermore, increased level of the MMP-2 transcript was followed by disappearance of fibronectin. Our findings suggest that TGF-beta1 plays an important role in ECM production in the early phase of acute pancreatitis, and that MMP-2 is involved in the subsequent healing process.

Animals↗

PubMed2001

Inflammatory bowel disease-like colitis in glycogen storage disease type 1b.

Chronic inflammatory bowel disease (IBD)-like colitis is occasionally associated with glycogen storage disease-type 1b (GSD-1b). We describe a 17-year old boy with GSD-1b who developed an IBD-like colitis. Roentgenography and colonoscopy showed the lead-pipe appearance of the colon and circumferential ulcers. Histopathologic examination revealed nonspecific inflammation without granulomatous lesions. High-dose granulocyte-colony stimulating factor (G-CSF) and sulfasalazine led to the resolution of the colitis, although neutropenia continued. Besides this case, 10 published cases of GSD-1b and IBD-like colitis were reviewed. All cases had severe neutropenia and/or neutrophil dysfunction. The mean onset of bowel disease was 12.3 years of age. Seven cases required surgical treatment. All five patients with G-CSF/GM-CSF therapy showed clinical remission. These findings suggest that IBD-like colitis is a grave complication of GSD-1b and that recurrent enteric infections due to neutrophil deficiency may contribute to the development of this bowel disease.

Adolescent↗

PubMed2001

Predicting the recurrence of ventricular tachyarrhythmias from T-wave alternans assessed on antiarrhythmic pharmacotherapy: a prospective study in patients with dilated cardiomyopathy.

BACKGROUND: Microvolt T-wave alternans (TWA) has been proposed as a useful index to identify patients at risk of ventricular tachyarrhythmias. Recent studies have demonstrated that antiarrhythmic drugs, such as amiodarone and procainamide, decrease the prevalence of TWA. In this study, we tested whether TWA in patients on antiarrhythmic pharmacotherapy significantly predicts the recurrence of ventricular tachyarrhythmias in patients with dilated cardiomyopathy. METHODS: To evaluate the ability to predict the recurrence of ventricular tachyarrhythmias, determinate TWA and left ventricular ejection fraction (LVEF) were prospectively assessed in 49 patients with ischemic or nonischemic dilated cardiomyopathy on antiarrhythmic pharmacotherapy for sustained ventricular tachycardia (VT) or ventricular fibrillation (VF). The pharmacotherapy consisted of class I (17 patients), III (29 patients), and IV (3 patients) antiarrhythmic drugs. The study endpoint was the first recurrence of sustained VT or VF on treatment during the follow-up period. RESULTS: TWA was positive on antiarrhythmic pharmacotherapy in 30 patients (61%). During a follow-up of 13 +/- 11 months, the sustained VT or VF recurred in 21 of the 41 patients (51%) with available follow-up data. The sensitivity of TWA and LVEF for predicting recurrence of ventricular tachyarrhythmias was 76 and 38%, specificity was 60 and 70%, positive predictive value was 67 and 57%, and negative predictive value was 71 and 52%. Kaplan-Meier event-free analysis revealed that TWA was a significant risk stratifier (P = 0.02), whereas LVEF was not. CONCLUSIONS: This prospective study suggests that TWA significantly predicts the recurrence of ventricular tachyarrhythmias, even on antiarrhythmic pharmacotherapy, in patients with dilated cardiomyopathy. TWA may also be a useful marker for evaluating the efficacy of antiarrhythmic drugs for ventricular tachyarrhythmias.

Adult↗

PubMed2001

Waveform dependence of pulsatile flow in a stenosed channel.

Bloodflow in arteries often shows a rich variety of vortical flows, which are dominated by the complex geometry of blood vessels, the dynamic pulsation of blood flow, and the complicated boundary conditions. With a two-dimensional model of unsteady flow in a stenosed channel, the pulsatile influence on such vortical fluid dynamics has been numerically studied in terms of waveform dependence on physiological pulsation. Results are presented for unsteady flows downstream of the stenosed portion with variation in the wavefiorms of systole and diastole. Overall, a train of propagating vortex waves is observed for all the cases, but it shows great sensitivity to the waveforms. The generation and development of the vortex waves may be linked to the presence of an adverse pressure gradient within a specific interval between two points of inflection of the systolic waveform. The adverse pressure gradient consists of a global pressure gradient that is found to be closely related to the dynamnics of' the pulsation, and a local pressure gradient, which is obsented to be dominated by the nonlinear vortex dynamics.

Arteries↗

PubMed2001

Complete nucleotide sequence of a Staphylococcus aureus exfoliative toxin B plasmid and identification of a novel ADP-ribosyltransferase, EDIN-C.

The complete nucleotide sequence of pETB, a 38.2-kb Staphylococcus aureus plasmid encoding the exfoliative toxin B (ETB), was determined. A total of 50 open reading frames were identified on the plasmid genome and, among these, 32 showed sequence similarity to known proteins. pETB contains three copies of IS257, which divide the pETB genome into three regions: (i) a cadmium resistance operon-containing region, (ii) a lantibiotic production gene-containing region, and (iii) the remaining part where genes for plasmid replication and/or maintenance are dispersed. In the third region, genes of various kinds of functions are present among the replication- and maintenance-related genes. They include two virulence-related genes, the etb gene and a gene encoding a novel ADP-ribosyltransferase closely related to EDIN, which belongs to the C3 family of ADP-ribosyltransferases modifying Rho GTPases. They also include genes for a cell wall-anchoring surface protein and a phage resistance protein. Based on the determined sequence of pETB, the genome structures of etb-bearing plasmids (ETB plasmids) from various clinical isolates were analyzed by the PCR scanning method. The data indicate that, although the ETB plasmids are highly heterogeneous in genome size, the fundamental genome organization is well conserved. The size variation of the plasmid is mainly attributed to defined regions which may be hot spots for gene shuffling.

Amino Acid Sequence↗

PubMed2001

Expression of extracellular calcium-sensing receptor in human osteoblastic MG-63 cell line.

We have previously shown the expression of the extracellular calcium (Ca2+o)-sensing receptor (CaR) in osteoblast-like cell lines, and others have documented its expression in sections of murine, bovine, and rat bone. The existence of the CaR in osteoblasts remains controversial, however, since some studies have failed to document its expression in the same osteoblast-like cell lines. The goals of the present study were twofold. 1) We sought to determine whether the CaR is expressed in the human osteoblast-like cell line, MG-63, which has recently been reported by others not to express this receptor. 2) We investigated whether the CaR, if present in MG-63 cells, is functionally active, since most previous studies have not proven the role of the CaR in mediating known actions of Ca2+o on osteoblast-like cells. We used immunocytochemistry and Western blotting with the specific, affinity-purified anti-CaR antiserum 4637 as well as Northern blot analysis and RT-PCR using a riboprobe and PCR primers specific for the human CaR, respectively, to show readily detectable CaR protein and mRNA expression in MG-63 cells. Finally, we employed the patch-clamp technique to show that an elevation in Ca2+o as well as the specific, allosteric CaR activator NPS R-467 (0.5 microM), but not its less active stereoisomer NPS S-467 (0.5 microM), activate an outward K+ channel in MG-63 cells, strongly suggesting that the CaR in MG-63 cells is not only expressed but is functionally active.

Aniline Compounds↗

PubMed2001

Ca(2+)-sensing receptor expression and PTHrP secretion in PC-3 human prostate cancer cells.

Prostate cancer metastasizes frequently to bone. Elevated extracellular calcium concentrations ([Ca(2+)](o)) stimulate parathyroid hormone-related protein (PTHrP) secretion from normal and malignant cells, potentially acting via the [Ca(2+)](o)-sensing receptor (CaR). Because prostate cancers produce PTHrP, if high [Ca(2+)](o) stimulates PTHrP secretion via the CaR, this could initiate a mechanism whereby osteolysis caused by bony metastases of prostate cancer promotes further bone resorption. We investigated whether the prostate cancer cell lines LnCaP and PC-3 express the CaR and whether polycationic CaR agonists stimulate PTHrP release. Both PC-3 and LnCaP prostate cancer cell lines expressed bona fide CaR transcripts by Northern analysis and RT-PCR and CaR protein by immunocytochemistry and Western analysis. The polycationic CaR agonists [Ca(2+)](o), neomycin, and spermine each concentration dependently stimulated PTHrP secretion from PC-3 cells, as measured by immunoradiometric assay, with maximal, 3.2-, 3.6-, and 4.2-fold increases, respectively. In addition, adenovirus-mediated infection of PC-3 cells with a dominant negative CaR construct attenuated high [Ca(2+)](o)-evoked PTHrP secretion, further supporting the CaR's mediatory role in this process. Finally, pretreating PC-3 cells with transforming growth factor (TGF)-beta(1) augmented both basal and high [Ca(2+)](o)-stimulated PTHrP secretion. Thus, in PTHrP-secreting prostate cancers metastatic to bone, the CaR could initiate a vicious cycle, whereby PTHrP-induced bone resorption releases [Ca(2+)](o) and TGF-beta stored within bone, further increasing PTHrP release and osteolysis.

Adenoviridae Infections↗

PubMed2001

Regulation of MAP kinase by calcium-sensing receptor in bovine parathyroid and CaR-transfected HEK293 cells.

Regulation of the extracellular signal-regulated kinase 1 and 2 (ERK1/2) pathway by the extracellular calcium (Ca2+o)-sensing receptor (CaR) was investigated in bovine parathyroid and CaR-transfected human embryonic kidney (HEKCaR) cells. Elevating Ca2+o or adding the selective CaR activator NPS R-467 elicited rapid, dose-dependent phosphorylation of ERK1/2. These phosphorylations were attenuated by pretreatment with pertussis toxin (PTX) or by treatment with the phosphotyrosine kinase (PTK) inhibitors genistein and herbimycin, the phosphatidylinositol-specific phospholipase C (PI-PLC) inhibitor U-73122, or the protein kinase C (PKC) inhibitor GF109203X and were enhanced by the PKC activator phorbol 12-myristate 13-acetate. Combined treatment with PTX and inhibitors of both PKC and PTK nearly abolished high Ca2+o-evoked ERK1/2 activation in HEKCaR cells, demonstrating CaR-mediated coupling via both Gq and G(i). High Ca2+o increased serine phosphorylation of the 85-kDa cytosolic phospholipase A2 (cPLA2) in both parathyroid and HEKCaR cells. The selective mitogen-activated protein kinase (MAPK) inhibitor PD98059 abolished high-Ca2+o)-induced ERK1/2 activation and reduced cPLA2 phosphorylation in both cell types, documenting MAPK's role in cPLA2 activation. Thus our data suggest that the CaR activates MAPK through PKC, presumably through Gq/11-mediated activation of PI-PLC, as well as through G(i)- and PTK-dependent pathway(s) in bovine parathyroid and HEKCaR cells and indicate the importance of MAPK in cPLA2 activation.

Animals↗

PubMed2001

Hypertension and neurovascular compression of the left lateral medulla oblongata in ischemic stroke.

Hypertension is a major risk factor for stroke. Neurovascular compression (NC) of the left ventrolateral medulla oblongata may cause arterial hypertension. We evaluated the relationship between the two ischemic stroke patients. We classified 69 patients under 50 years old (49 men and 20 women, aged 43.6 +/- 7.3 years) based on magnetic resonance imaging findings as follows: NC patients (n = 38; 10 with NC on the right side, 18 with NC on the left side, and 10 with NC on both sides) and non-NC patients (n = 31). We compared the following clinical characteristics between the two groups: (1) risk factors for stroke, including hypertension, diabetes mellitus, hypercholesterolemia, and smoking and (2) stroke subtype. Hypertension was more frequent in the NC group than in the non-NC group (58 vs. 19%, p = 0.001). Hypertension was more frequent in patients with left-side NC than in those with right-side NC (78 vs. 20%, p = 0.005). No other differences were observed between the two groups. Twelve patients presented with atherothrombotic stroke, 16 with cardioembolic stroke, 24 with lacunar stroke and 17 with stroke of miscellaneous etiology. NC was significantly more common in patients with lacunar stroke as compared with those affected by other stroke subtypes (p = 0.015). We found a significant relationship between hypertension and NC of the ventrolateral medulla oblongata on the left side in ischemic stroke patients younger than 50 years of age. Some patients with lacunar stroke may have hyptertension related to NC.

Adolescent↗

PubMed2001

Blood flow in the left atrial appendage and embolic stroke in nonvalvular atrial fibrillation.

It is unclear if low flow velocity in the left atrial appendage (LAA) is a predisposing factor to stroke in patients with nonvalvular atrial fibrillation (NVAF). We investigated flow velocity in the LAA in NVAF patients in relation to a past history of stroke and other potential embolic sources. We measured and analyzed peak flow velocities into (FV-in) and out of (FV-out) the LAA in a middle portion of the LAA in 35 NVAF patients by transesophageal echocardiography (TEE). We divided the NVAF patients into 3 groups: the Eaf group had a history of embolic stroke without any other potential embolic sources; the Emulti group had other potential embolic sources, and the control group had no embolic history. FV-in and FV-out in the Eaf group (12.3 +/- 6.7 and 10.2 +/- 7.3 cm/s) were significantly lower than those in the control group (24.3 +/- 11.3 and 19.9 +/- 8.8 cm/s; multicomparison Scheffé's test, p = 0.0123 and 0.0395, respectively). The Emulti group varied in those values from less than 5 to above 35. Low flow velocity in the LAA seems to be a predisposing factor for stroke in NVAF patients without any other sources of emboli.

Aged↗

PubMed2001

Role of P-selectin and intercellular adhesion molecule-1 in TNB-induced colitis in rats.

It has been proposed that neutrophil-endothelial cell interactions mediated by adhesion molecules are involved in the pathogenesis of inflammatory bowel disease. The objective of the present study was to determine the effects of monoclonal antibodies (MAbs) directed against endothelial adhesion molecules, P-selectin and intercellular adhesion molecule-1 (ICAM-1), in rats with colitis induced by 2,4,6-trinitrobenzene sulfonic acid (TNB). Colonic inflammation was induced by administering an enema of TNB dissolved in 50% ethanol (120 mg/ml) to male Wistar rats (at a total volume of 0.25 ml per rat) after a 48-hour fast. Anti-P-selectin MAb or anti-ICAM-1 MAb was injected via the tail vein at a dose of 1 mg/kg after the induction of colitis. Rats in the control group received nonbinding mouse immunoglobulin G1. The plasma level of soluble P-selectin showed an increase within 48 h after the TNB enema. Colonic inflammation was assessed at 1 week after TNB administration. The colonic damage score and the wet weight of the colon were significantly decreased by treatment with either MAb. The increase of myeloperoxidase (MPO) activity, an index of neutrophil accumulation, and the increase of thiobarbituric acid-reactive substances (TBA-RS), an index of lipid peroxidation, in the colonic mucosa were inhibited by both MAbs. These results suggest that neutrophil-endothelial cell interactions via P-selectin and ICAM-1 play an important role in the development of TNB-induced colitis in rats.

Animals↗

PubMed2001

Increased expression of heme oxygenase-1 and bilirubin accumulation in foam cells of rabbit atherosclerotic lesions.

Heme oxygenase-1 (HO-1) catalyzes the regiospecific oxidative degradation of heme to biliverdin IXalpha, iron, and carbon monoxide. Biliverdin IXalpha is subsequently reduced to bilirubin IXalpha by biliverdin reductase. HO-1 expression is induced under various disease conditions, including atherosclerosis, but it is unknown whether HO-1 catalyzes heme breakdown in the regions at risk. Using hypercholesterolemic rabbits fed a cholesterol-enriched diet, we attempted to demonstrate the involvement of HO-1 induction and bilirubin IXalpha production in atherosclerotic regions. Expression levels of HO-1 mRNA were elevated in the aortas of hypercholesterolemic rabbits. In situ hybridization and immunohistochemistry revealed that mRNA and protein of HO-1 are induced in endothelial cells and foam cells (lipid-filled macrophages) in atherosclerotic lesions. Furthermore, immunohistochemistry with the use of an anti-bilirubin-IXalpha monoclonal antibody, 24G7, demonstrated accumulation of bilirubin IXalpha in foam cells, indicating that heme is actually degraded in atherosclerotic lesions. Remarkably, bilirubin IXalpha, like HO-1 protein, is predominantly accumulated in the perinuclear regions of foam cells. These results provide the first in vivo evidence of the colocalization of HO-1 and bilirubin IXalpha in foam cells, suggesting a role of HO-1 induction in the modulation of macrophage activation in atherosclerosis.

Animals↗