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Biomedical subjects

N Kitamura

Publications and source records attributed to N Kitamura.

At least 271 records · Page 15Linked to original sources
PubMed1994

Effects of nifedipine and Bay K 8644 on contractile activities in single skeletal muscle fibers of the frog.

The effects of dihydropyridine derivatives on contractile activity were examined in single fibers of frog skeletal muscles. Both nifedipine and Bay K 8644 enhanced twitch responses regardless of the presence or absence of Ca2+ without any effects on the resting membrane potential, evoked action potential and Ca2+ sensitivity of the contractile machinery. Twitch responses enhanced by Bay K 8644, but not by nifedipine, were partially reduced by adenine, an inhibitor of Ca(2+)-induced Ca2+ release from sarcoplasmic reticulum, suggesting the involvement of Ca(2+)-induced Ca2+ release in Bay K 8644-induced potentiation of the twitches. Both nifedipine and Bay K 8644 caused a dose-dependent potentiation of K+ contractures without any effects on the membrane potential in the presence of Ca2+, but inhibited the contractures in the absence of Ca2+. These results suggest that dihydropyridine derivatives modify contractile activities of skeletal muscles by modulating the dihydropyridine receptors on the surface of T-tubules acting as voltage sensors.

3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethy↗
PubMed1994

Proteolytic activation of hepatocyte growth factor in response to tissue injury.

Hepatocyte growth factor (HGF) is a potent mitogen for hepatocytes and renal tubular epithelial cells and may play an important role in regeneration following hepatic and renal injury. HGF is first synthesized as a single chain precursor which is then converted to a heterodimeric form by proteolytic processing. This proteolytic conversion is required for HGF to function as a mitogen. In this study, we examined whether the proteolytic activation of HGF occurred in response to hepatic and renal injury. HGF remained as an inactive single chain form in the liver, kidney, lung, and spleen of normal rats. The production of HGF markedly increased in the liver after hepatotoxin treatment and in the kidney after nephrotoxin treatment. A significant portion of the increased HGF was converted to the active heterodimeric form, whereas in other tissues, conversion did not occur although the production of HGF increased in some of them. Furthermore, an enzymatic activity that converts the single chain form of HGF to the active heterodimeric form was detected in the injured liver but not in the normal liver. These results indicate that HGF is proteolytically activated in response to tissue injury, and this activation is mediated by an enzymatic activity which is induced exclusively in the injured tissues. Thus, the proteolytic activation system functions in vivo as a mechanism for localizing HGF activities to injured tissues.

Animals↗
PubMed1994

Extracellular matrix components regulating glandular differentiation and the formation of basal lamina of a human pancreatic cancer cell line in vitro.

The interaction between the extracellular matrix and human tumor-cell clones S2-013 and S2-020, derived from a pancreatic cancer cell line (SUIT-2), was examined in vitro, using various cell differentiation-promoting matrices in two- and three-dimensional cultures. S2-013 cells (well-differentiated tubular adenocarcinoma in xenografts in nude mice) cultured in Matrigel formed glandular structures. Ultrastructural observation revealed a morphological polarity of cells and a distinct basal lamina. On the other hand, S2-020 cells (poorly differentiated tubular adenocarcinoma in xenografts) cultured in Matrigel formed neither glandular structures nor a basal lamina, but only cell aggregates. The morphology of these two sublines cultured in Matrigel expressed the histological degree of differentiation which they presented in nude mice. In contrast, in type I collagen gel, S2-013 cells formed glandular structures without a basal lamina, and in soft agar, they were able to form neither glandular structures nor a basal lamina. S2-020 cells cultured in type I collagen gel or soft agar formed the same simple cell aggregates as in Matrigel. Matrices used in a three-dimensional culture influenced the degree of differentiation in S2-013 cells but had no effect on the morphological differentiation in S2-020 cells. To detect the factors which induce basal lamina formation, S2-013 cells were cultured on a microporous membrane coated with extra-cellular matrix components such as laminin, type IV collagen, and fibronectin. S2-013 cells formed a basal lamina only on the laminin. These cell lines may be useful in investigating the mechanisms regulating the formation of glandular structures and basal lamina.

Adenocarcinoma↗
PubMed1994

Heterogeneities of attachment, chemotaxis, and protease production among clones with different metastatic potentials from a human pancreatic cancer cell line.

The present study extends our investigations into the metastatic heterogeneity among four clonal cell lines (S2-007:H, S2-013:M1, S2-020:M2, and S2-028:L) from a human pancreatic cancer cell line (SUIT-2), and extends our discussion the positive correlation between metastatic potential and the type I collagenase activity of the cells, focusing on their interaction with extracellular matrix. Ability to attach to the reconstituted basement membrane (Matrigel) was higher for clone H than clone L during an observation period of 30-60 min, whereas clones M1 and M2 were found to be intermediate in ability. In densitometric and radioactive studies, clone L exhibited the lowest collagenolytic activity against mouse and human type IV collagen, while clone H exhibited the highest activity in the densitometric study and clone M1 was the highest in the radioactive study. The production of urinary-type plasminogen activator was highest in clone L and lowest in clone H. On the other hand, tissue-type plasminogen activator was highest in clone M2 and low in both clones H and L. Clone M2 exhibited the highest chemotactic activity toward diluted Matrigel, whereas clone L had the lowest activity. On the whole, these clones showed heterogenous interactions with an extracellular matrix. It is suggested that the attachment activity to basement membrane and the type IV collagenolytic activity of the cells may be positively correlated with their metastatic potential, whereas the production of urinary-type plasminogen activator was negatively correlated, but confirmation of these findings awaits further study.

Cell Adhesion↗
PubMed1994

Morphological study of the surface structure of the omasal laminae in cattle, sheep and goats.

The mucosal relief of the omasum in cattle, sheep and goats was examined by the naked eye, stereoscopic microscope and scanning electron microscope. The mucosal relief of the omasum showed wide variations both between and within these species. Omasal papillae on the laminae varied highly in shape, i.e. conical, rounded, claw-like, wart-like, finger-like etc. They decreased gradually in size from the oral to the aboral region of the omasal lamina. Ridge-like structures and linear arrangements of the papillae were also seen on the omasal laminae of cattle and sheep. Many grooves and folds were found on the lateral surface of the omasal papillae in adult cattle and on the inter-papillar surface of the laminae of all three species. The mucosal relief of the omasum in cattle seemed to be more well-developed than those of sheep and goats. Dietary effects on the omasal mucosa were also discussed.

Animals↗
PubMed1994

Is lamina muscularis mucosae present in the ruminal mucosa of cattle? Immunohistochemical and ultrastructural approaches.

The cells in the condensed fibrous layer in the lamina propria of the ruminal mucosa of the calves and cows were studied at the light microscopic level. Abundant actin-immunoreactive cells were detected both in the calves and cows, while desmin-immunoreactive cells were moderate in frequency in the cows and low or absent in the calves. Vimentin-immunoreactive cells were abundant in the cows but moderate to low in frequency in the calves. These cells were distributed to form a condensed layer being more abundant in the ruminal papillae than the interpapillar mucosae in the cows and equal in the papillae and interpapillar mucosae in the calves. At the ultrastructural level, smooth muscle cells and fibroblasts were abundant in the deep core of the ruminal papilla of the cows. The present results suggest that the condensed fibrous layer revealed in the ruminal mucosae contains smooth muscle cell population which could be regarded as the specialized lamina muscularis mucosae.

Animals↗
PubMed1994

Comparative study of five types of IABP balloons in terms of incidence of balloon rupture and other complications: a multi-institutional study.

The Multi-Institutional IABP Balloon Study Group in Japan (14 institutions) conducted a retrospective nonrandomized study to elucidate the incidence and type of IABP balloon-related complications relative to design and durability of five different clinically available balloons: TMP (n = 960), Kontron (n = 943). Datascope (n = 485), Mansfield (n = 226), and Aries (n = 189) balloons. A total of 2,803 patients (1,973 males, 830 females, mean age 62.1 years) spent a total of 243,856 h on the pump. Forty-nine balloons (1.7%) ruptured as recognized by the appearance of blood in the catheter (39 cases) or console alarm (4 cases). Ten patients required surgical removal of the balloon due to entrapment. Other IABP balloon-related complications requiring surgical intervention or with a lethal outcome occurred in 89 patients (3.2%). They included lower limb ischemia (61 cases), hematoma (11 cases), extensive dissection (6 cases), perforation (5 cases), entrapment without balloon rupture (3 cases), and mesenteric infarction (3 cases). The incidence of rupture, other major complications, and total complications, respectively, for each balloon was 0, 2.7, and 2.7 for TMP, 1.6, 4.3, and 5.9% for Kontron, 4.1, 1.9, and 6.0% for Datascope, 1.3, 2.7, and 4.0% for Mansfield, and 5.8, 3.7, and 9.5% for Aries. In conclusion, the TMP balloon demonstrates a significantly lower rate of rupture while the incidence of other complications for the 5 balloons is not significantly different.

Equipment Failure↗
PubMed1994

Immunohistochemical study of the distributions of the peptide- and catecholamine-containing nerves in the omasum of the sheep.

The distribution in the sheep omasum of peptide- and catecholamine-containing neurons was investigated by an immunohistochemical technique using antibodies against six neuropeptides and two catecholamine-synthesizing enzymes. In the myenteric plexus, both nerve cell bodies and nerve fibers were positively immunostained for substance P (SP), methionine enkephalin (ENK), vasoactive intestinal polypeptide (VIP), neuropeptide Y (NPY) and galanin (GAL). In contrast, immunoreactivity specific for calcitonin gene-related peptide (CGRP), tyrosine hydroxylase (TH) and dopamine-beta-hydroxylase (DBH) was detected only in nerve fibers. In the omasal wall, nerve fibers with SP- and ENK-like immunoreactivity were prominent in the outer muscle layer, while numerous nerve fibers with VIP-, NPY- and GAL-like immunoreactivity were observed in the inner muscle layer. In the lamina propria mucosae, and in particular in the omasal papillae, a dense network of peptide-containing nerves was found. The distribution of nerves with CGRP-like immunoreactivity was different from that of other immunoreactive nerves. The networks of nerves with TH-, DBH- and NPY-like immunoreactivity were concentrated around the vascular components. The results of this study indicate the complexity of the enteric nervous system in the sheep omasum, reflecting the multiple functions of the nerves in the regulation of motility and/or absorption and secretion.

Animals↗
PubMed1994

Immunohistochemical study of the distribution of endocrine cells in the gastrointestinal tract of the lesser mouse deer (Tragulus javanicus).

The occurrence and distribution of endocrine cells in the gastrointestinal tract of the lesser mouse deer, Tragulus javanicus, were studied immunohistochemically. Fourteen types of endocrine cells immunoreactive for serotonin, somatostatin, enteroglucagon, pancreatic glucagon, bovine pancreatic polypeptide (BPP), gastrin, substance P, motilin, gastric inhibitory polypeptide (GIP), cholecystokinin (CCK), methionine-enkephalin-Arg6-Gly7-Leu8 (MENK-8), secretin, neurotensin, peptide tyrosine tyrosine (PYY) and chromogranin were revealed. Chromogranin-, serotonin-, somatostatin- and enteroglucagon-immunoreactive cells were detected in all regions examined, while pancreatic glucagon-immunoreactive cells, except in the proper gastric gland region, were not found in other regions of the gastrointestinal tract. Few BPP-immunoreactive cells in either the proper gastric gland or pyloric gland regions and abundant gastrin-immunoreactive cells in the pyloric gland region were observed. Restricted distributions of substance P-, GIP-, gastrin-, motilin-, CCK-, MENK-8-, secretin-, neurotensin- and BPP-immunoreactive cells in the small intestine, and BPP-, substance P-, PYY- and motilin-immunoreactive cells in the large intestine were noted. The important findings include the presence of BPP-immunoreactive cells in the abomasum, pancreatic glucagon-immunoreactive cells in the proper gastric gland region, and substance P- and motilin-immunoreactive cells in the large intestine. It is suggested that the distribution pattern of gut endocrine cells in the lesser mouse deer is more similar to that in the pig than in the domestic ruminants so far reported.

Abomasum↗
PubMed1994

Eosinophil chemiluminescence response to cytokines and opsonized zymosans in atopic dermatitis.

Chemiluminescence (CL) responsiveness of eosinophils (Eos) to zymosan particles coated with either IgG, C3 or both and eosinophilopoiesis-modulating cytokines was investigated in patients with atopic dermatitis (AD), and an attempt was made to correlate these CL responses with serum levels of eosinophil cationic protein (ECP) which increased in response to the extent of AD severity, but not blood eosinophil counts. A high degree of positive correlation existed between serum levels of ECP and either IgG containing opsonized zymosan- or interleukin-5 (IL-5)-induced CLs. The CL values induced by these two stimuli appeared to be directly correlated with the intensity of each ligand-linked receptor expression. These results suggested that Fc gamma RII-and/or IL-5R-mediated eosinophil activation at the site of lesional skins might implicate in deterioration of cutaneous inflammation, and consequently cause an elevation of serum levels of ECP in AD.

Blood Proteins↗
PubMed1994

The nerve cell bodies found in the ovine omasal laminae.

A histological study was made on the omasum of sheep, cows, sika deer, and Japanese serows in order to confirm the existence of the submucosal nerve cell bodies in the omasal laminae. In the present study, seventeen submucosal nerve cell bodies were found in seven sections from four out of twenty-two sheep.

Animals↗
PubMed1994

Tyrosine phosphorylation of beta-catenin and plakoglobin enhanced by hepatocyte growth factor and epidermal growth factor in human carcinoma cells.

The effect of hepatocyte growth factor/scatter factor (HGF/SF) and epidermal growth factor (EGF) on cadherin-mediated adhesion of human carcinoma cells was studied. HGF/SF induced scattering of colonic adenocarcinoma HT29 and gastric adenocarcinomas MKN7 and MKN74 cells. Likewise, EGF induced scattering of HT29 and MKN7 cells. These cells expressed E-cadherin, which was concentrated at cell-cell contact sites. When the scattering of these cells was induced by HGF/SF or EGF, the E-cadherin concentration at cell-cell boundaries tended to decrease. Immunoblotting analyses, however, demonstrated that these growth factor treatments did not alter the expression of E-cadherin and E-cadherin-associated proteins, alpha- and beta-catenin and plakoglobin. beta-Catenin, plakoglobin and an unidentified 115-kDa molecule associated with E-cadherin were found to be phosphorylated at tyrosine residues, and these phosphorylations were enhanced by the growth factor treatments. These results suggest that HGF/SF and EGF may modulate the function of the cadherin-catenin system via tyrosine phosphorylation of cadherin-associated proteins.

Cadherins↗
PubMed1994

Protein-free culture of the human pancreatic cancer cell line, SUIT-2.

A human pancreatic cancer cell line (SUIT-2), usually cultured in serum-supplemented medium (DMEM/FBS), was adapted to protein-free conditions using a 1:1 mixture of DMEM and Ham's F12 medium (DMEM/F12). The cells have been maintained in DMEM/F12 for more than 2 years, with over 50 passages. The SUIT-2 cells grew in DMEM/F12 with a doubling time of 35.7 h, which was similar to that in DMEM/FBS (35.0 h). The cellular morphology was similar in both media. Type IV collagenolytic activity was detected in the conditioned media from cells grown in DMEM/F12. The secretion of CEA and CA19-9 initially decreased in DMEM/F12. CEA was not detected after passage 5 (p5) but the concentration of CA19-9 did not decrease further after the first few serial passages in protein-free medium. Xenografts of SUIT-2 cells cultured in DMEM/F12 remained tumorigenic and could form metastatic tumors in nude mice. In conclusion, SUIT-2 cells grown in protein-free media continued to produce CA19-9 and type IV collagenase in vitro and formed metastatic tumors in vivo.

Animals↗
PubMed1994

[The efficacy of both antegrade and retrograde cardioplegia in coronary artery bypass surgery].

We evaluated the efficacy of the cardioplegic myocardial protection by combining antegrade cardioplegic induction via the aortic root with retrograde cardioplegia via the coronary sinus in patients who had LAD stenosis or occlusion with collateral circulation. In study I, forty-six patients were divided into two groups: antegrade group (group A; 32 cases), which were perfused by only antegrade fashion via the aortic root, and bi-directional group (group B; 14 cases), which were perfused by combining antegrade with retrograde fashion. In study II, patients were divided into four groups: 32 cases in group A were divide into three subgroups by the direction of the collateral circulation to LAD in preoperative coronary angiograms: group I (antegrade collateral circulation; 18 cases), group II (retrograde collateral circulation; 7 cases), group III (99% stenosis with delayed filling; 7 cases) and group B was as group IV. Myocardial injury was assessed with the use of enzyme indexes (total CPK, CPK-MB, %MB, peak CPK, peak CPK-MB and peak % MB) in study I and study II. There was no significant difference between the two groups in study I and the four groups in study II in terms of patients' profile, graft materials, number of grafts, aortic cross-clamping time, total cardiopulmonary bypass time and surgical results. Total CPK level in group B was significantly lower (p < 0.05) compared with group A at the point of 12 hr and 1 day after surgery and peak CPK level was also significantly lower (p < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Collateral Circulation↗
PubMed1994

[Free arterial graft for coronary bypass grafting].

Free arterial grafts were aggressively placed in 39 patients (1991 to 1993). There were 34 males and 5 females, and mean age was 59.9 year old. Of 85 arterial grafts, 41 were free grafts, and their materials included left and right internal thoracic artery (LITA, RITA) and right gastroepiploic artery (GEA). There were one free LITA-left anterior descending coronary artery (LAD), seven free RITA-LAD, three free RITA-diagonal branch (Dx), 14 free RITA-left circumflex coronary artery (LCX), 10 free RITA-right coronary artery (RCA), two sequential RITA-Dx-LCX, one free GEA-Dx, two free GEA-LCX, and one free GEA-RCA bypass. Of 41 free arterial grafts, 38 were in the aorta-coronary position, and the proximal anastomosis was constructed first under single aortic cross-clamping to get the larger anastomotic sites for both at the proximal and distal ends of the arterial graft. The proximal sites of the remaining 3 arterial grafts were placed to concomitantly utilized saphenous vein grafts in two patients and RCA in one patient because of their shortness. Perioperative complications included no exploration for bleeding, myocardial infarction in one (2.6%), intra-aortic balloon pumping in three (7.7%), and wound complications in two (5.1%). 28 cases (72%) were completely revascularized with only arterial grafts. Of 41 free arterial grafts studied within one month after operation, all grafts were patent. All patients were free from angina after a 27 months mean follow-up. We believe that the proximal anastomosis technique for free arterial graft we used could be acceptable alternative for many surgeons. These excellent results justify wider use of free arterial grafts.

Abdominal Muscles↗