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Toshio Ohhashi

Publications and source records attributed to Toshio Ohhashi.

At least 19 recordsLinked to original sources
PubMed2006

Noradrenaline-induced smooth muscle relaxation in the specific region of canine facial vein: implications for facial and cranial circulation.

This study was performed to investigate the heterogeneity of physiological and pharmacological properties in segments of the facial veins with special reference to selective brain cooling. Canine facial veins were isolated and the isometric tension of each segment was measured using the organ bath technique. Vessels in the segments of the facial veins that run opposite to the buccal cavity automatically produced myogenic tone and tended to show spontaneous contractions, but vessels in other segments did not. When no contractile agent was used for precontraction, noradrenaline and adrenaline produced dose-dependent relaxations in the former venous segments, but contractions in the latter ones. A Schild plot analysis for metoprolol against denopamine and for ICI118,551 against salbutamol showed that the venous segments running opposite the buccal cavity contained both beta(1)- and beta(2)-adrenoceptors, but the other venous segments contained only beta(2)-adrenoceptors. Electrical field stimulation-induced tetrodotoxin-sensitive relaxations in the former venous segments were diminished by pretreatment with metoprolol, but not with ICI118,551, indicating that the electrical stimulation-induced relaxation may be related to the activation of beta(1)-adrenoceptors in the venous smooth muscles. In conclusion, the heterogeneity of the functional properties, especially in the distribution of beta-adrenoceptors, in different segments of canine facial veins was observed in the present study, and autoregulatory mechanisms, humoral mechanisms, and neural mechanisms were suggested to affect cranial venous drainage.

Adrenergic Agonists↗
PubMed2006

Immunohistochemical demonstration of proliferating lymphatic vessels in colorectal carcinoma and its clinicopathological significance.

Lymphatic metastasis to the regional lymph nodes through the lymphatic vessels is an important indicator of poor prognosis in many types of malignant tumors. Recently, much attention has been paid to lymphangiogenesis for its possible role on tumor progression in various carcinomas. However, morphological evidence that lymphatic vessels actively proliferate in colorectal carcinoma has not been reported. Here, we first devised a triple immunostaining method to detect proliferating lymphatic vessels utilizing antibody to Ki-67 antigen as a marker of cell proliferation, antibody to cytokeratin as an epithelial cell marker, and antibody to podoplanin as a lymphatic vessel-specific marker. Ki-67/podoplanin-immunoreactivity enabled us to identify proliferating lymphatic vessels, while cytokeratin immunoreactivity allowed us to distinguish proliferating lymphatic vessels from Ki-67/cytokeratin-positive carcinoma cells in lymphatic lumens. Analyzing 64 colorectal carcinoma patients' samples using this technique, we showed that both lymphatic vessel density and proliferating activity of lymphatic vessels were significantly increased in colorectal carcinoma tissues compared with their normal counterparts. We then examined the correlation between the degree of lymphangiogenesis and patients' prognosis or clinicopathological variables, but no statistically significant differences were obtained in these analyses. Thus, these results combined together indicate that extensive lymphangiogenesis occurs in colorectal carcinoma, but that the degree of lymphangiogenesis alone is not an independent prognostic factor for this disease.

Adult↗
PubMed2005

Comparison of biomechanical and histological properties in dog carotid arteries injured by neointima or intimal thickening.

A general formula (Oka and Azuma's equation) has been rigorously derived for the circumferential wall tension in a hollow cylindrical tube in equilibrium. To evaluate the validity and usefulness of Oka and Azuma's equation, T = P(1) x r(1) - P(2) x r(2) (T, circumferential wall tension; P(1) and P(2), internal and external pressures of the tube; r(1) and r(2), the corresponding internal and external radii), we experimentally investigated changes in circumferential wall tension of noninjured (control) and injured dog common carotid arteries by using a newly developed apparatus with a photo- and X-ray-sensitive image sensor. We also studied histological features of the control and injured arteries with special reference to the relation of biomechanical properties. Two types of animal models with injured arteries--balloon-induced neointima or external collar-induced intimal thickening--were adopted in the present study. In the control arteries, the circumferential wall tension was experimentally confirmed to change from negative to positive by an increase in intraluminal pressure ranging from 50 to 180 mmHg. The critical intraluminal pressure that produced 0 dyne/cm of the circumferential wall tension was around 135 mmHg. The activation of arterial smooth muscles caused a significant increase in the critical pressure in the control arteries. In the arteries injured by neointima, the critical intraluminal pressure was significantly lower than that in the control. The activation of smooth muscles also significantly increased the critical pressure in the injured arteries. Histological examination demonstrated the existence of a circumferential neointimal formation along with a shortening of the internal diameter. In other arteries injured by intimal thickening, the circumferential wall tension was always negative at intraluminal pressure ranging from 50 to 180 mmHg. Newly developed structures consisted of elastic and collagen fibers, smooth muscles, and extracellular matrix in the intima and media of the injured arteries. These experimental findings suggest that the circumferential wall tension of dog common carotid arteries has been confirmed experimentally to become negative. We have also concluded that circumferential wall tension calculated with Oka-Azuma's equation may be one of the best parameters for evaluating changes in the biomechanical and histological properties of pathologically injured arteries.

Animals↗
PubMed2005

Arachidonic Acid-Induced COX-1 and COX-2-Mediated Vasodilation in Rat Gingival Arterioles In Vivo.

The roles of cyclooxygenase (COX) and prostaglandins (PGs) in the regulation of vasoreactivity of rat gingival arterioles in vivo were evaluated by sing an intravital microscope. The superfusion of indomethacin (a nonselective COX inhibitor) or SC-560 (a selective COX-1 inhibitor) onto the gingiva significantly constricted the arterioles, though NS-398 (a selective COX-2 inhibitor) did not affect the diameter of the arterioles. The SC-560-mediated constriction of the arterioles was completely reversed by an additional treatment with arachidonic acid (AA). The superfusion of AA, beraprost-Na (an analogue of PGI2) or PGE2 onto the gingival significantly dilated the arterioles dose-dependently. The AA-induced dilation of the arterioles was significantly reduced by the treatment with SC-560 or NS-398. The expression of COX-1 and COX-2 were positive in the endothelium, but not the smooth muscles, of the arterioles. The expression of PGE synthase (PGES) was found only in the smooth muscles, but not the endothelium, of the arterioles. Neither the endothelium nor the smooth muscles of the arterioles expressed PGI synthase (PGIS). These findings suggest that the COX-2-mediated PG cascade may collaborate with the COX-1 pathway in the regulation of arteriolar myogenic activity in rat gingiva in the case of the supply of a large amount of AA.

Animals↗
PubMed2005

Cilostazol, an inhibitor of type 3 phosphodiesterase, produces endothelium-independent vasodilation in pressurized rabbit cerebral penetrating arterioles.

We investigated the effects of cilostazol, a potent inhibitor of cGMP-inhibited cAMP phosphodiesterase, on mechanical activity of isolated pressurized rabbit cerebral penetrating arterioles with special reference to the function of the endothelium. Both cilostazol and milrinone, another inhibitor of cAMP phosphodiesterase, produced vasodilation of the cerebral penetrating arterioles in a dose-dependent manner. Pretreatment with selective inhibitors of cyclooxygenase or nitric oxide synthase, or chemical denudation of the endothelial cells caused no significant effect on the cilostazol-mediated vasodilation of the cerebral arterioles. A selective large-conductance calcium-activated potassium channel inhibitor, iberiotoxin, and a selective protein kinase A inhibitor, H-89, caused no significant effect on the cilostazol-mediated vasodilation. In the cerebral arterioles, low concentration (10(-6)M) of cilostazol or milrinone caused a significant shift of the dose-vasodilatory response curve for adenosine to the left. These findings suggest that cilostazol produces vasodilation independent of the presence of the endothelium or activation of endogenous vasodilative prostaglandins, nitric oxide, calcium-activated potassium channel and protein kinase A. In conclusion, the vasodilator action of cilostazol may, in part, contribute to the beneficial effect of preventing lacunar cerebral infarction in patients with functional damage of the endothelium in cerebral penetrating arterioles.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed2005

Effective permeability of hydrophilic substances through walls of lymph vessels: roles of endothelial barrier.

The wall effective permeability of hydrophilic substances labeled with fluorescent dyes was evaluated in an isolated cannulated rat single lymph vessel through a videomicroscope system. Sodium fluorescein (NaFl; 332 mol wt) and FITC-dextrans (4,400, 12,000, and 71,200 mol wt) were administered into the intraluminal space of the lymph vessels and then excited by a Xenon lamp. Changes in the fluorescence intensity of the dyes were continuously measured by a silicon-intensified target camera through appropriate filters. The net flux of each dye in the wall of the lymph vessels was calculated by the relationship between the fluorescence intensity and the concentration of the dyes. NaFl and FITC-dextran 4,400 in the intraluminal space of isolated rat lymph vessels significantly penetrated the wall of the lymph vessels. FITC-dextran 12,000 in the intraluminal space of isolated rat lymph vessels slightly passed through the lymphatic wall, whereas FITC-dextran 71,200 did not penetrate the wall. Intraluminal pressures ranging from 4 to 8 cm H(2)O did not significantly affect the net flux of dyes used in the present study. After administration of 3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonate into the lymph vessels, the net flux of FITC-dextran 4,400 and 12,000 but not 71,200 was augmented significantly. These results suggest that small molecular hydrophilic substances (< or =4,400) are permeable from the intraluminal to extraluminal space of isolated lymph vessels and that the endothelial cell surface structure may play a barrier role in the effective permeability of large molecular hydrophilic substances (4,400 to 12,000) through the wall of the lymph vessels.

Animals↗
PubMed2005

Effects of exercise intensity, posture, pressure on the back and ambient temperature on palmar sweating responses due to handgrip exercises in humans.

We have, by using newly developed ratemeters, attempted to examine the effects of exercise intensity, posture, pressure on the skin of the back, and ambient hyperthermic conditions (approximately 30 degrees C) on the 5-s handgrip exercise-mediated responses of active palmar sweating in humans. Thirty-five right-handed male (n=5) and female (n=30) volunteer students (20.2+/-1.3 years old) participated in the present study. Oral explanation of only the isometric handgrip exercise (IHG) caused a rapid and oscillatory response (pre-operational) of active palmar sweating in almost all subjects (10 of 14 subjects). Performing the IHG for 5-s caused a significant increase in active sweating rate (operation-mediated response) in both ipsi- and contra-lateral palmar surfaces of the thumbs of all subjects. The operation-mediated responses of active palmar sweating to the IHG were reproducible, resulting in no habituation. The increase of operation-mediated responses to the IHG was dependent upon exercise intensity (100-25% maximal voluntary contractions). The IHG-mediated ipsi- and contra-lateral responses of active palmar sweating were significantly decreased by changing the body posture from a seated to a supine position or by pressing the skin of the back. Ambient hyperthermic conditions (approximately 30 degrees C) for 60 min also resulted in a significant decrease in the back-pressure-dependent reduction of the operation-mediated responses of active palmar sweating to the IHG. In conclusion, in order to optimize the precision and reproducibility of clinical tests involving palmar sweating responses, it is important that subjects maintain a constant handgrip force and posture and that ambient temperature be kept under normothermic conditions.

Adult↗
PubMed2005

Involvement of NO and EDHF in flow-induced vasodilation in isolated hamster cremasteric arterioles.

Flow-induced vasodilation in hamster cremasteric arterioles was investigated with special reference to the roles of nitric oxide (NO) and endothelium-derived hyperpolarizing factor (EDHF). Arterioles (approximately 60 microm resting diameter) were cannulated, and suffused with MOPS solution at 37 degrees C (mean intraluminal pressure: 80 cm H(2)O). Step increases in the perfusate flow elicited a dose-dependent vasodilation, which was almost proportional to the increases in calculated wall shear stress (WSS). N(omega)-nitro L-arginine methyl ester (L-NAME, 100 microM) reduced the flow-induced vasodilation by approximately 50%, whereas indomethacin (10 microM) produced no significant effect. In the presence of L-NAME, the residual vasodilation was eliminated by treatment with the cytochrome P-450 monooxygenase inhibitor 17-octadecynoic acid (17-ODYA, 50 microM), sulfaphenazol (10 microM), tetraethylammonium (TEA, 3 mM; a nonselective Ca(2+)-activated K(+) channel inhibitor), or charybdotoxin (ChTX, 0.1 microM; intermediate or large conductance Ca(2+)-activated K(+) channel inhibitor). In the absence of L-NAME, the dilation was also reduced by approximately 50% by treatment with 17-ODYA, TEA, or ChTX. The residual vasodilation was eliminated by additional treatment with L-NAME. The inhibitor of ATP-sensitive K(+) channels (K(ATP)), glibenclamide, also caused a significant, but partial, reduction of the flow-induced vasodilation. The residual vasodilation was completely reduced by additional treatment with 17-ODYA, but not L-NAME. These findings suggest that in hamster cremaster, higher flow rate produces NO, K(ATP), and EDHF vasodilation of the arterioles under physiological conditions.

Abdominal Muscles↗
PubMed2005

A new preparation for visualizing lymphatic flow pathway in isolated rat lymph nodes.

BACKGROUND: There is no reported study in which the lymphatic flow pathway in lymph nodes has been visualized and investigated in in vitro studies. The purpose of the present study is first to develop an isolated rat lymph node preparation circulated through the afferent and efferent lymph vessels in order to visualize lymphatic flow pathway within the node by using a video microscope system, and then to evaluate lymphatic flow dynamics by using fluorescence-labeled substances. METHODS AND RESULTS: In the present study, rat iliac lymph node was isolated. The afferent and efferent lymph vessels of the lymph node were cannulated with glass micropipettes in an organ chamber, while the small-sized arteries and veins connected to the lymph node were secured with sutures. Krebs-bicarbonate solution with or without fluorescent probes [FITCdextran, mol. weight; 77,000 and/or fluoresbrite carboxylate-microspheres (FC-microspheres) mean diameter of 1 microm] was circulated through the lymph vessels of the node. The time-dependent lymphatic pathway of fluorescent probes was investigated with a video microscope system. FTIC-dextran first spread through the cortex and subsequently reached the medulla of the lymph node. A follicle-like structure became evident in the cortex. FITC-dextran appeared in the efferent lymph vessel at 109 +/- 21 sec after its circulation began, while FC-microspheres distributed in the lymph node did not emerge from the node within 20 min after their introduction. CONCLUSIONS: In vitro preparations constructed in the present study will enable us to visualize the lymphatic flow pathway of fluorescent substances within the isolated iliac lymph nodes of rats in the absence of blood circulation.

Animals↗
PubMed2005

[Capillary permeability and macromolecular exchange with special reference to structure of microvascular walls].

This paper reviews current concepts of capillary permeability of lipophilic and hydrophilic solutes, and macromolecular exchange across the microcirculation with special reference to structure of microvascular walls. Lipophilic and hydrophilic solutes must be differentiated because the barriers encountered by these classes of substances in the capillary walls are very different. Most hydrophilic solutes are mainly restricted to the paracellular pathway, whereas lipophilic solutes use the cellular pathway. Toward the end of the last century, Starling proposed that fluid flow through capillary walls is passive. He suggested that the energy for transcapillary fluid flow lay in the differences in hydrostatic and osmotic pressures between the circulating plasma and the tissues. It has been established that most proteins present in plasma cross capillary and venular walls, diffuse through the tissues, and return to the plasma via the lymphatic system. Thus both small and large pores are necessary to describe the movement of large molecules across the capillary and venular walls.

Animals↗
PubMed2004

Current topics of physiology and pharmacology in the lymphatic system.

We have reviewed physiological significance of rhythmical spontaneous contractions of collecting lymph vessels, which play a pivotal role in lymph transport and seem to control lymph formation through changing the pacemaker sites of the rhythmic contractions and contractile patterns of the lymphangions. A characteristic feature that the rhythmic pump activity works in vivo physiologically under the specific environment of lower oxygen tension in lymph (25-40 mm Hg) has been evaluated. With the characteristic feature, generation of endogenous nitric oxide (NO) from lymphatic endothelial cells and/or activation of ATP-sensitive potassium channels (K(ATP)) are reviewed to play crucial roles in the regulation of lymph transport at physiological or pathophysiological conditions. Chemical substances released from malignant tumor cells and tumor-derived parathyroid hormone-related peptide (PTHr-P) are also shown to cause a significant reduction of lymphatic pump activity through generation of endogenous NO and activation of K(ATP) channels. Finally, we have discussed physiological significance and roles of the lower oxygen tension in lymph, generation of endogenous NO, and activation of K(ATP) in lymph formation, lymph transport, and the functions of lymph nodes.

Adenosine Triphosphate↗
PubMed2004

ATP inhibits pump activity of lymph vessels via adenosine A1 receptor-mediated involvement of NO- and ATP-sensitive K+ channels.

We examined the effects of ATP on intrinsic pump activity in lymph vessels isolated from the rat. ATP caused significant dilation with a cessation of lymphatic pump activity. Removal of the endothelium or pretreatment with Nomega-nitro-L-arginine methyl ester (L-NAME) significantly reduced ATP-induced inhibitory responses of lymphatic pump activity, whereas reduction was not suppressed completely by 10(-6) M ATP. L-arginine significantly restored ATP-induced inhibitory responses in the presence of L-NAME. ATP-induced inhibitory responses in lymph vessels with endothelium were also significantly, but not completely, suppressed by pretreatment with glibenclamide. 8-Cyclopentyl-1,3-dipropylxanthine (a selective adenosine A1 receptor antagonist), but not suramine (a P2X and P2Y receptor antagonist) or 3,7-dimethyl-1-proparglyxanthine (a selective adenosine A2 receptor antagonist), significantly decreased ATP-induced inhibitory responses. alpha,beta-methylene ATP (a selective P2X and P2Y receptor agonist) had no significant effect on lymphatic pump activity. In some lymph vessels with endothelium (24 of 30 preparations), adenosine also caused dose-dependent dilation with a cessation of lymphatic pump activity. L-NAME significantly reduced the inhibitory responses induced by the lower (3 x 10(-8)-3 x 10(-7) M) concentrations of adenosine. Glibenclamide or 8-cyclopentyl-1,3-dipropylxanthine also significantly suppressed adenosine-induced inhibitory responses. These findings suggest that ATP-induced dilation and inhibition of pump activity of isolated rat lymph vessels are endothelium-dependent and -independent responses. ATP-mediated inhibitory responses may be, in part, related to production of endogenous nitric oxide, involvement of ATP-sensitive K+ channels, or activation of adenosine A1 receptors in lymphatic smooth muscle and endothelium.

Adenosine Triphosphate↗
PubMed2004

Lymphodynamic properties governing sentinel lymph nodes.

Biological properties of lymph microvessels include characteristics of spontaneous contractions of lymph vessels, nitric oxide (NO)-mediated modulation of active lymph pump activity, flow-induced production and release of NO from lymphatic endothelial cells, and localization of NO synthase in cultured lymphatic endothelial cells. B16-BL6 melanoma cells release factors that inhibit active pump activity in isolated lymph microvessels. We have found that basic fibroblast growth factor (bFGF) induces significant proliferation and migration of canine cultured lymphatic endothelial cells. This growth factor facilitates the formation of capillary-like tubes by the cultured endothelial cells.

Animals↗
PubMed2004

PDGF-BB induces intratumoral lymphangiogenesis and promotes lymphatic metastasis.

Cancer metastases are commonly found in the lymphatic system. Like tumor blood angiogenesis, stimulation of tumor lymphangiogenesis may require the interplay of several tumor-derived growth factors. Here we report that members of the PDGF family act as lymphangiogenic factors. In vitro, PDGF-BB stimulated MAP kinase activity and cell motility of isolated lymphatic endothelial cells. In vivo, PDGF-BB potently induced growth of lymphatic vessels. Expression of PDGF-BB in murine fibrosarcoma cells induced tumor lymphangiogenesis, leading to enhanced metastasis in lymph nodes. These data demonstrate that PDGF-BB is an important growth factor contributing to lymphatic metastasis. Thus, blockage of PDGF-induced lymphangiogenesis may provide a novel approach for prevention and treatment of lymphatic metastasis.

Animals↗
PubMed2003

Arithmetic calculation, deep inspiration or handgrip exercise-mediated pre-operational active palmar sweating responses in humans.

We examined the effects of repetitive mental stimulation such as arithmetic calculations with sequential subtraction or physical tasks such as handgrip exercise and deep breathing on active palmar sweating responses in humans. Thirty-three healthy, male and female volunteer students (20.4+/-2.1 years) participated in the present study. The responses of active palmar sweating were evaluated by using the newly developed ratemeter. The galvanic skin response (GSR) was also recorded in 10 out of 33 subjects. The oral explanation of the stimulation or tasks caused a rapid and wavy active palmar sweating response. The pre-operational responses of active palmar sweating to the stimulation or tasks were also observed by the GSR recording. The mental stimulation- and physical tasks-mediated pre-operational responses were significantly reduced by the trials. The mental stimulation or physical tasks also caused a rapid and oscillatory response of active palmar sweating during operation of the stimulation or tasks. The operation-mediated responses to physical tasks were observed ipsilaterally and contralaterally. The physical task-mediated responses were also reproducible, resulting in no habituation. In contrast, the operation-mediated responses to mental stimulation were reduced significantly by the trials, resulting in a marked habituation. The findings suggest that the mental stimulation- and physical tasks-mediated pre-operational responses of active palmar sweating obtained by using the newly developed ratemeter will make useful tests for evaluating neuronal activity of limbic system including amygdala, sympathetic sudomotor activity in the palmar skin and functional properties of the palmar sweat glands.

Adult↗
PubMed2003

Establishment of rat lymphatic endothelial cell line.

OBJECTIVE: The objective of the present study was to establish a rat lymphatic endothelial cell line and then to investigate the morphological and immunohistochemical properties of the cells. METHODS: The lymphatic endothelial cells of rat thoracic ducts were isolated enzymatically by trypsin digestion and were cultured in endothelium growth medium (EGM)-2 in an atmosphere of low oxygen (5% O(2), 5% CO(2), and 90% N(2)) or high oxygen (21% O(2), 5% CO(2), and 74% N(2)). RESULTS: The number of the cells cultured in the low-oxygen atmosphere was significantly larger than that obtained in the high-oxygen atmosphere. The cultured cells in the low-oxygen atmosphere showed a monolayer with uniform cobblestone appearance, suggesting the morphological properties of endothelial cells. Factor VIII-related antigen and cell surface carbohydrates (i.e., D-galactose alpha and D-N-acetylgalactosamine alpha) were found on the lymphatic cultured cells. The phagocytosis of 1,1-diocadecyl1-3,3,3',3'-tetramethylindo-carbocyanine perchlorate-labeled acetylated low-density lipoprotein also was observed in the cultured cells. The cytoskeleton protein F-actin was located on the plasma membrane of the cultured cells as circumferential thin bundles and in the cytoplasma as filamentous bundles. CONCLUSIONS: The present study indicates that the choice of EGM-2 as a culture medium and the hypoxic atmosphere ( approximately 5%) enabled us to establish rat lymphatic endothelial cell line.

Actins↗
PubMed2003

Rho-Rho kinase pathway is involved in the regulation of myogenic tone and pump activity in isolated lymph vessels.

To evaluate whether or not Rho-Rho kinase pathway is involved in the regulation of mechanical activity of lymph vessels, effects of Y-27632 and okadaic acid on lymph pump activity and myogenic, pressure- and agonist-induced tone were examined in isolated rat lymph vessels. Y-27632 caused a significant dilation with a cessation of the lymph pump activity. Y-27632 also produced a dose-related dilation of the lymph vessels precontracted by norepinephrine (NE)-, U-46619- or 80 mM KCl. Okadaic acid significantly constricted the lymph vessels and reduced the frequency of the lymph pump activity. Okadaic acid also produced a dose-related constriction of the lymph vessels precontracted by NE or U-46619. The Y-27632-induced decrease of the frequency of lymph pump activity was significantly reversed by the pretreatment with okadaic acid. In the presence of Y-27632, the pressure-mediated tone of the lymph vessel was significantly decreased. On the other hand, okadaic acid significantly increased the pressure-mediated tone. These findings suggest that Rho kinase and myosin phosphatase activity in lymphatic smooth muscles may contribute to the regulation of lymph pump activity and may be also involved in the control of myogenic pressure- and agonist-induced tone.

15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5↗