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Biomedical subjects

K Iwata

Publications and source records attributed to K Iwata.

At least 19 recordsLinked to original sources

Modulation of collagen synthesis by tumor necrosis factor alpha in cultured vascular smooth muscle cells.

Collagen synthesis in vascular smooth muscle cells (SMCs) after exposure to tumor necrosis factor alpha (TNF-alpha) was investigated using a culture system. The synthesis of collagenase-digestible proteins (CDP) and noncollagenous proteins (NCP) was evaluated by the [3H]proline incorporation. It was shown that TNF-alpha markedly suppresses the incorporation of [3H]proline into both CDP and NCP in confluent cultures of SMCs but not in sparse cultures of the cells. Such a marked suppression by TNF-alpha was not observed in confluent bovine aortic endothelial cells and human fibroblastic IMR-90 cells. In confluent SMCs, the synthesis of CDP was more strongly inhibited by TNF-alpha than that of NCP. When the CDP synthesis was stimulated by transforming growth factor beta, TNF-alpha suppressed the stimulation in both confluent and sparse SMCs. Human SMCs synthesized types I, III, IV and V collagens; TNF-alpha markedly decreased the relative proportion of types IV and V. It was therefore suggested that TNF-alpha modulates the collagen synthesis by SMCs depending on their cell density and modifies the formation of atherosclerotic lesions.

Animals

Molecular dynamics of MHC genesis unraveled by sequence analysis of the 1,796,938-bp HLA class I region.

The intensely studied MHC has become the paradigm for understanding the architectural evolution of vertebrate multigene families. The 4-Mb human MHC (also known as the HLA complex) encodes genes critically involved in the immune response, graft rejection, and disease susceptibility. Here we report the continuous 1,796,938-bp genomic sequence of the HLA class I region, linking genes between MICB and HLA-F. A total of 127 genes or potentially coding sequences were recognized within the analyzed sequence, establishing a high gene density of one per every 14.1 kb. The identification of 758 microsatellite provides tools for high-resolution mapping of HLA class I-associated disease genes. Most importantly, we establish that the repeated duplication and subsequent diversification of a minimal building block, MIC-HCGIX-3.8-1-P5-HCGIV-HLA class I-HCGII, engendered the present-day MHC. That the currently nonessential HLA-F and MICE genes have acted as progenitors to today's immune-competent HLA-ABC and MICA/B genes provides experimental evidence for evolution by "birth and death," which has general relevance to our understanding of the evolutionary forces driving vertebrate multigene families.

Base Pairing

Enantioselective binding sites on bovine serum albumin to dansyl amino acids.

The enantioselective binding sites on bovine serum albumin were examined by HPLC using 19 racemic 5-N, N-dimethylamino-1-naphthalenesulfonyl derivatives of alpha-amino acids (dansyl amino acids) as chiral probes. On a bovine serum albumin bonded chiral stationary phase, seven L-forms eluted faster than their D-forms, while ten D-forms eluted before their L-forms. It was speculated that either two classes or two different binding sites exist on bovine serum albumin which can be distinguished by N-dansyl-L-proline and N-dansyl-D-norvaline. This was confirmed by fluorometric experiments where non-fluorescent 1-naphthalenesulfonyl derivatives were synthesized and competitive adsorption experiments were performed.

Amino Acids

Inhibition of matrix metalloproteinases prevents allergen-induced airway inflammation in a murine model of asthma.

Although matrix metalloproteinases (MMPs) have been reported to play crucial roles in the migration of inflammatory cells through basement membrane components in vitro, the role of MMPs in the in vivo accumulation of the cells to the site of inflammation in bronchial asthma is still obscure. In this study, we investigated the role of MMPs in the pathogenesis of bronchial asthma, using a murine model of allergic asthma. In this model, we observed the increase of the release of MMP-2 and MMP-9 in bronchoalveolar lavage fluids after Ag inhalation in the mice sensitized with OVA, which was accompanied by the infiltration of lymphocytes and eosinophils. Administration of tissue inhibitor of metalloproteinase-2 to airways inhibited the Ag-induced infiltration of lymphocytes and eosinophils to airway wall and lumen, reduced Ag-induced airway hyperresponsiveness, and increased the numbers of eosinophils and lymphocytes in peripheral blood. The inhibition of cellular infiltration to airway lumen was observed also with tissue inhibitor of metalloproteinase-1 and a synthetic matrix metalloproteinase inhibitor. These data suggest that MMPs, especially MMP-2 and MMP-9, are crucial for the infiltration of inflammatory cells and the induction of airway hyperresponsiveness, which are pathophysiologic features of bronchial asthma, and further raise the possibility of the inhibition of MMPs as a therapeutic strategy of bronchial asthma.

Administration, Inhalation

Genotypes of TT virus (TTV) compared between liver disease patients and healthy individuals using a new PCR system capable of differentiating 1a and 1b types from others*.

TT virus (TTV) lacks obvious pathogenicity; almost all of the infected hosts are symptom-free. A possibility remains, however, that certain strains can cause liver disease while most others are non-pathogenic. Genotypes 1 a and 1 b have been proposed to contain such pathogenic strains. To test this possibility, we constructed a PCR system capable of detecting TTV of the 1 a and 1 b genotypes differentially from the other genotypes, and compared the frequencies of these genotypes between patients with liver disease of unknown etiology (n=42) and healthy individuals (n=50). The assay comprised 3 steps: i) PCR to amplify a 3.2-kb fragment using universal primers; ii) 2nd-round PCR, starting from the 3.2-kb amplicon, for a approximately 280-nt fragment by use of genotype 1-specific primers; and iii) digestion of the approximately 280-nt amplicon with MboI and BanI to discriminate between 1 a and 1 b. Eventually, 40 (95%) of the patients and 47 (94%) of the controls were positive for the 3.2-kb amplicon, and the 1 a, 1 b, 1 a+1 b, and non-1 genotypes of TTV were found in 2 (5%) vs 4 (9 percent), 5 (13%) vs 4 (9%), 1 (3%) vs 1 (2%) and 32 (80%) vs 38 (81%) of the 40 patients and 47 controls, respectively: the distribution was almost identical between the two groups. The hypothesis that the genotype 1 of TTV may be more closely associated with liver disease than other genotypes was not supported by this study.

Base Sequence

Mechanism of salmon sperm decondensation by nucleoplasmin.

Removal of protamine from DNA-protamine (salmine, protamine from salmon sperm) complexes by nucleoplasmin was examined and compared with that of poly-L-glutamic acid (PLGA) using turbidity and ethidium bromide (EB) treatment methods. When nucleoplasmin or PLGA was added to a DNA-protamine complex solution, turbidity was decreased and the amount of EB intercalated into DNA was increased. These results suggest that nucleoplasmin and PLGA can remove protamine from DNA-protamine complexes. The effect of nucleoplasmin was more potent than that of PLGA. Direct interaction of nucleoplasmin with protamine was confirmed by mixing experiments using circular dichroism (CD) and fluorescence spectroscopies. Results suggest that nucleoplasmin is bound to protamine in a 1:1 ratio and that Trp126 is located near a hydrophilic region containing a polyglutamic acid tract of nucleoplasmin which was obviously influenced by its binding with protamine. It would appear that the polyglutamic acid tract in nucleoplasmin plays a critical role for binding with protamine.

Animals

Long-term effect of epalrestat on cardiac autonomic neuropathy in subjects with non-insulin dependent diabetes mellitus.

To evaluate the effect of long-term administration of an aldose reductase inhibitor on diabetic cardiovascular autonomic neuropathy, 22 subjects with non-insulin dependent diabetes mellitus (NIDDM, 11 men and 11 women, mean age; 64.8 +/- 7.8 years, duration of diabetes; 18.3 +/- 5.6 years) were administered epalrestat, one type of aldose reductase inhibitor, for 36 months. The changes in the coefficient of variation of the R-R interval (CV(R R)) during rest and the QTc interval were compared with 43 age-matched NIDDM (controls). During the study, the CV(R R) value gradually decreased in the controls, while it slightly increased in subjects treated with epalrestat. After 36 months, the CV(R R) value (2.31 +/- 1.09%) in subjects treated with epalrestat was significantly (P < 0.05) higher than that (1.84 +/- 0.75%) in the controls. There were no significant differences in QTc intervals in both groups. These results suggest that long-term administration of an aldose reductase inhibitor may be available for cardiac autonomic neuropathy in even relatively older diabetic subjects with long duration.

Aged

Real time assessment of myocardial revascularization during coronary artery bypass surgery by means of ultrasonic integrated backscatter.

OBJECTIVE: The recovery of cyclic variation (CV) of ultrasonic integrated backscatter (IB) may provide a more sensitive predictor of the success of myocardial revascularization. This study was designed to elucidate the possibility of real time assessment of coronary artery bypass grafting (CABG) using CV of IB. METHODS: We studied 10 patients (61 +/- 4 years old) with the perfused areas by stenosed or occluded LAD without myocardial infarction. There were six ischemic dysfunctional areas, and four ischemic but non-dysfunctional areas. The CV of IB was measured before and just after extracorporeal circulation (ECC). Wall motion was analyzed by segmental wall thickening during systole at the same time of the IB analysis during CABG and at 3 weeks after CABG. Those 10 areas were completely revascularized. RESULTS: In the non-dysfunctional areas, wall thickening did not change and remained at normal values before and after ECC, and 3 weeks after CABG (31 +/- 3% 29 +/- 3% and 29 +/- 5%, respectively). The magnitude of CV of IB did not also change before and after ECC (8.0 +/- 1.6 dB and 7.8 +/- 1.3 dB). However, in the ischemic dysfunctional areas, while wall thickening did not change before and after ECC (21 +/- 5% and 20 +/- 5%), it increased and reached similar values as the non-dysfunctional regions at 3 weeks after CABG (26 +/- 7%, P < 0.01 vs. before and after ECC values). The magnitude of CV of IB increased even after ECC (3.71 +/- 0.4 dB vs. 7.4 +/- 3.5 dB, P < 0.05), and reached the same level as those in the non-dysfunctional areas. There was a significant relationship between wall thickening at 3 weeks after bypass grafting and magnitude of CV of IB after ECC (r = 0.67, P < 0.05). CONCLUSIONS: Improvement in wall motion was gradually attained after bypass grafting. On the contrary, an increase in the magnitude of CV of IB was obtained immediately after myocardial revascularization. Our data suggest that CV of ultrasonic IB method can provide close real time information regarding the effectiveness of bypass surgery.

Coronary Artery Bypass

Dynamin and rab5 regulate GRK2-dependent internalization of dopamine D2 receptors.

Dopamine D2 receptors (D2Rs; short form, which is one of the alternative splicing variants) expressed in COS-7 cells are internalized in an agonist-dependent manner only when G protein-coupled receptor kinase 2 (GRK2) is coexpressed [Ito, K., Haga, T., Lameh, J. & Sadée, W., (1999) Eur. J. Biochem. 260, 112-119]. We have examined the effects of coexpression of dynamin, a small molecular mass GTP-binding protein, rab5A, and their mutants on the internalization of D2Rs in the presence of both dopamine (10 or 100 microM) and GRK2. The rate and extent of D2R internalization was increased or decreased by coexpression of dynamin I or a dominant-negative form of dynamin I (dynamin I K44E), respectively. The effects of coexpressing these two dynamins were more prominent at 10 microM dopamine than at 100 microM. In the presence of 10 microM dopamine, internalization of D2R was completely suppressed when dynamin I K44E was coexpressed, and the half-life (t 1/2) of D2R internalization decreased relative to cells not expressing dynamin from 82 to 29 min when dynamin I was coexpressed. Internalization of D2Rs was facilitated or suppressed by coexpression of a constitutively active form of rab5A (rab5A Q79L) or a dominant-negative form of rab5A (rab5A S34N), respectively. The t 1/2 of D2R internalization at 10 microM dopamine decreased from 82 to 16 min in cells coexpressing rab5A Q79L. The effect of coexpression of rab5A S34N was more apparent at 100 microM dopamine than at 10 microM; the t 1/2 of D2R internalization at 100 microM dopamine increased from 20 to 56 min and the proportion of internalized D2Rs after 120 min decreased from 53 to 28%. These results indicate that the internalization of D2Rs is dependent on the action of dynamin as well as GRK2, and is regulated by the action of rab5A.

Animals

Intraportal perfusion of prostaglandin E1 attenuates hepatic postischaemic microcirculatory impairments in rats.

BACKGROUND: The efficacy of intraportal perfusion with prostaglandin E1(PGE1) in decreasing postischaemic hepatic microcirculatory damage was studied in rats. METHODS: An extrahepatic portosystemic shunt was created by attaching the spleen to a subcutaneous site on the left lateral wall of the abdomen in male Wistar rats weighing between 200 and 350 g. Four weeks later, when the shunt was mature, the portal vein and hepatic artery were occluded for 60 min. The animals were divided into the following three groups according to the type of intraportal perfusion during the ischaemic phase: group 1 consisted of untreated animals; group 2, animals perfused with lactated Ringer's solution; and group 3, animals perfused with PGE1 (0.1 microg/kg per min). The hepatic microcirculation was observed under an inverted intravital microscope after the injection of fluorescent dyes to label leucocytes and damaged cells 30 and 60 min after reperfusion. The liver was removed 60 min after reperfusion and stained immunohistochemically using 1A29, an anti-rat intercellular adhesion molecule-1 (ICAM-1) antibody. RESULTS: The leucocyte velocity during reperfusion was lowest in group 1 and highest in group 3. Of the three groups, group 3 showed the least leucocyte adhesion to the sinusoidal walls and terminal venules, the lowest damaged cell count and the lowest ICAM-1 expression on the sinusoidal walls. CONCLUSION: The results of this study suggest that hepatic perfusion with PGE1 markedly alleviates microcirculatory damage associated with ischaemia and reperfusion through the inhibition of leucocyte-endothelium interactions.

Alprostadil

A study on polysomnographic observations and subjective experiences under sensory deprivation.

We investigated the relationship between subjective experiences and polysomnographic observations under sensory deprivation (SD). The results can be divided into two types: (i) visual images were perceived frequently, accompanied by alpha waves or theta waves in electroencephalogram and frequent rapid eye movements (REM); (ii) the subjects fell in deep sleep without perception of visual images. The perceptions of visual images with alpha waves or theta waves and REM are supposed to be different from those in usual wakefulness and sleep. These results suggest that the SD could disclose different aspects of consciousness from the conventionally categorized states such as wakefulness and sleep.

Adult

A high-fat diet aggravates tubulointerstitial but not glomerular lesions in obese Zucker rats.

BACKGROUND: Despite a large body of evidence that manipulation of dietary fat alters glomerular lesions, reports regarding the effects of dietary fat on tubulointerstitial lesions are limited. Obese Zucker rats (OZR) spontaneously develop glomerular and tubulointerstitial lesions in association with hyperlipidemia. We sought to elucidate the effects of dietary fat on glomerular and tubulointerstitial lesions in OZR versus lean Zucker rats (LZR) and to assess the involvement of macrophages in the development of these lesions. METHODS: We fed LZR and OZR either a low- (1%) or high-fat (20%) diet. After 30 weeks of the specified diet, the creatinine clearance (Ccr) and renal histology as well as plasma lipid concentrations were examined. For morphological evaluation, glomerular sclerosis (GSI) and tubulointerstitial indices (TII) were each determined by a point-counting method. Infiltrating macrophages were stained immunohistochemically using an avidin-biotin complex technique. RESULTS: The high-fat diet increased the plasma low-density lipoprotein concentration in OZR. Both low- and high-fat OZR groups had higher GSI and TII than LZR receiving either diet. The high-fat diet aggravated TII but not GSI or Ccr in OZR; conversely, high fat intake worsened GSI and Ccr but not TII in LZR. Tubulointerstitial macrophages were most prominent in the high-fat OZR group, followed by the low-fat OZR group. Glomerular macrophages were similar in number in all groups. CONCLUSIONS: The manipulation of dietary fat has diverse effects on the kidney. A high-fat diet aggravated macrophage-mediated tubulointerstitial lesions in OZR, whereas in LZR, the diet induced glomerulosclerosis.

Albuminuria

Collagen fibrillar network in the optic nerve head of normal monkey eyes and monkey eyes with laser-induced glaucoma--a scanning electron microscopic study.

PURPOSE: To examine the three-dimensional organization of collagen fibrils in the lamina cribrosa of normal monkey eyes and monkey eyes with laser-induced glaucoma. METHODS: Intraocular pressure elevation and glaucomatous optic discs were obtained in one eye of three adult monkeys by repeated applications of argon laser to the chamber angle. The monkey eyes were enucleated, and the collagen fibrillar network was investigated by scanning electron microscopy after cell maceration with 10% sodium hydroxide and conductive staining. RESULTS: In normal monkey eyes, round to oval shaped regular laminar pores through which axon bundles exited were observed in the lamina cribrosa. The straight, column-like pores or openings were formed by multilayered laminar plates that aligned vertically in parallel with the optic nerves. The surface of the laminar plates was covered by delicate, loosely arranged collagen fibrils. The inner surface of the pores was smooth, made up of well-packed collagen fibers. In glaucomatous eyes, the laminar pores were clogged by tightened collagen fibrils. The inner surface of the pores was irregular, and the pores were narrowed or distorted. CONCLUSIONS: Alterations in the three-dimensional organization of collagen fibrils were demonstrated in the optic nerve head of glaucomatous monkey eyes. The architectural changes may affect the flexibility and resilience required of the lamina cribrosa in supporting optic nerve fibers.

Animals

Inverse relation of body-surface activation-recovery interval and recovery time to activation time in normal subjects: stronger correlation and more heterogeneous distribution in activation-recovery interval than in recovery time.

The activation-recovery interval (ARI), measured directly from the myocardium, has shown a good correlation with the action potential duration (APD) in experiments. APD has been reported to be inversely related to the activation time (AT). However, no studies have examined the correlation between the body-surface ARI and AT in normal subjects. Fifty normal subjects (25 men and 25 women) were studied to elucidate the relationship between the body-surface ARI and AT. The body-surface AT was defined as the duration between the QRS onset and the minimum dV/dt of the QRS wave, and ARI as the interval between the minimum dV/dt of the QRS wave and the maximum dV/dt of the T wave in each lead of an 87 unipolar lead system. We also measured the recovery time (RT) defined as the duration between the QRS onset and the maximum dV/dt of the T wave. ARI was inversely correlated with AT (r = -0.73). RT was also inversely correlated with AT (r = -0.61), however, RT had a less heterogeneous distribution than ARI (148 ms vs 159 ms). There were no differences between male and female subjects in the relation between ARI and RT or in the body-surface distribution of ARI and RT. These findings suggest that the body-surface ARI may reflect recovery properties over the cardiac surface and that APD may distribute inhomogeneously over the human cardiac surface with a longer RT over an area with a shorter AT. ARI calculated from body-surface ECG may be a useful noninvasive and repeatedly measurable estimate of APD.

Adolescent

Medullary dorsal horn neuronal activity in rats with persistent temporomandibular joint and perioral inflammation.

Studies at spinal levels indicate that peripheral tissue or nerve injury induces a state of hyperexcitability of spinal dorsal horn neurons that participates in the development of persistent pain and hyperalgesia. It has not been demonstrated that persistent injury in the orofacial region leads to a similar state of central hyperexcitability in the trigeminal system. The purpose of the present study was to conduct a parametric analysis of the response properties of nociceptive and nonnociceptive neurons in trigeminal nucleus caudalis (medullary dorsal horn, MDH) in a rat model of persistent orofacial inflammation. Neurons were recorded extracellularly and classified as low-threshold mechanoreceptive (LTM, n = 49), wide dynamic range (WDR, n = 82), and nociceptive-specific (NS, n = 11) neurons according to their response properties to mechanical stimuli applied to their cutaneous receptive fields (RFs). The inflammation was induced 24 h before the recordings by injecting complete Freund's adjuvant (CFA) into the temporomandibular joint (TMJ) capsule or the perioral (PO) skin. The mean areas of the high-threshold RFs of WDR neurons in TMJ (8.66 +/- 0.61 cm(2), n = 25) and PO (5.61 +/- 2.07 cm(2), n = 25) inflamed rats were significantly larger than those in naive rats (1.10 +/- 0. 16 cm(2), n = 32). The mean RF size in TMJ-inflamed rats also was significantly larger than that in PO-inflamed rats (P < 0.01). Furthermore the mean area of the RFs of NS neurons (3.74 +/- 1.44 cm(2), n = 5) was significantly larger in TMJ inflamed rats as compared with naive rats (0.4 +/- 0.09 cm(2), n = 3) (P < 0.05). The background activity in the TMJ- and PO-inflamed rats was generally greater in WDR and NS neurons, but less in LTM neurons, when compared with naive rats. The responses of WDR neurons to noxious mechanical stimuli were increased significantly in TMJ-inflamed rats (P < 0.05) as compared with naive rats. WDR neuronal responses to mechanical stimulation also were increased in PO-inflamed rats but to a lesser extent than in TMJ-inflamed rats. The injection of CFA into the TMJ or PO skin resulted in reduced responses of LTM neurons to mechanical stimuli. The responses of MDH nociceptive neurons to 48-55 degrees C heating were greater in inflamed rats as compared with naive rats. A subpopulation of WDR neurons recorded from TMJ (n = 4 of 10)- or PO (n = 3 of 13)-injected rats responded to cooling in addition to heating of the RFs but did not grade their responses with changes in stimulus intensity. These results indicate that persistent orofacial inflammation produced hyperexcitability of MDH nociceptive neurons. TMJ inflammation resulted in more robust changes in MDH nociceptive neurons as compared with PO inflammation, consistent with previous studies of increased inflammation, increased MDH Fos-protein expression, and increased MDH preprodynorphin mRNA expression in this deep tissue orofacial model of pain and hyperalgesia. The inflammation-induced MDH hyperexcitability may contribute to mechanisms of persistent pain associated with orofacial deep tissue painful conditions.

Animals

Effect of a novel non-steroidal anti-inflammatory drug (M-5011) on cytokine levels in rats with monosodium urate crystal- induced pleurisy.

We evaluated the effects of a new non-steroidal anti-inflammatory drug (NSAID), d-2-[4-(3-methyl-2-thienyl)phenyl]propionic acid (M-5011), and indomethacin on the production of arachidonate metabolites and pro-inflammatory cytokines in male Sprague-Dawley rats with monosodium urate crystal (MSU)-induced pleurisy. Levels of tumor necrosis factor (TNF), interleukin (IL)-1 and IL-6 in the pleural exudate were determined by biological assays, while prostaglandin E2 (PGE2), leukotriene B4 (LTB4) and cytokine-induced chemoattractant-1 (CINC-1) levels were quantified by enzyme immunoassays. Orally administered M-5011 (5 mg/kg) decreased the pleural exudate volume at 3 and 4 hr after MSU injection. Indomethacin (10 mg/kg) decreased the volume at 3-5 hr. These drugs reduced the number of leukocytes in the pleural cavity at 6 hr. Both NSAIDs also reduced the content of PGE2 in the exudate without affecting LTB4 levels. Increased productions of both IL-6 and CINC-1 in the exudate were reduced by pretreatment with M-5011 or indomethacin, and TNF levels in the exudate were increased by pretreatment of these drugs. Thus, M-5011 inhibits the production of both IL-6 and CINC-1 at lower doses than those of indomethacin, and the inhibitory effect of M-5011 on CINC-1, but not IL-6, may partly contribute to the inhibition of leukocyte infiltration in rats with MSU-induced pleurisy.

Animals

Age-related bone loss: relationship between age and regional bone mineral density.

We assessed the changes in regional bone mineral density according to age and examined the relationship between various regional bone mineral densities. The study was conducted in 985 Japanese women divided into < 50-years group (n = 435) and > or = 50 years group (n = 550). The total body bone mineral density and that of the head, arm, leg, thoracic (T)-spine, lumbar (L)-spine, ribs, and pelvis were measured using dual energy x-ray absorptiometry. There was a significant generalized reduction of bone mineral density in all regions after the age of 50 years. The most marked age-related decrease was observed in the L-spine. Bone mineral densities in all regions significantly correlated to each other in both age groups, but the degree of significance varied among regions. The relationship between bone mineral density of the L-spine and that of T-spine regions was the most significant in both groups. In the < 50-years group, the correlation between bone mineral density of the pelvis and that of L-spine and T-spine was the highest, followed by that between the pelvis and the leg. On the other hand, in the > or = 50-years group, the correlation between bone mineral density of the pelvis and that of the leg was the highest, but not the L-spine or T-spine. Since spine measurements are affected by vertebral deformity and/or aortic calcification, our findings suggest the pelvis may be a useful region for screening measurements of bone mineral density, especially in older women.

Absorptiometry, Photon