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We created a driving simulation test for assessing drivers’ hazard-perception skills by measuring their palmar sweating response (PSR), skin potential reflex (SPR), and ability to operate the steering wheel, accelerator, and brake. We recruited 52 elderly people who were aged ≥60 years and were active drivers. These participants undertook the driving simulation test, and we measured their PSR, SPR, and device operation responses. PSR tended to be greater in hazard scenes that involved anticipation or complexity processes, suggesting the involvement of factors such as the participants’ readiness to anticipate hazards and their emotional changes. SPR response was faster in hazard scenes that involved a surprise process. SPR response was faster than braking response, except in scenes where the participants had only a fleeting moment to react to the hazard, suggesting that SPR is a suitable evaluation index for hazard perception timing. Two participants were suspected of having decreased cognitive function according to the Mini-Mental State Examination. These individuals exhibited PSR and SPR responses that were not consistent with the hazard scenes, and they made errors in their operation of the driving simulator. These findings highlight the need to examine the impact of decreased cognitive function on hazard perception.

Stromal cells, together with extracellular matrix components, provide a tumor microenvironment that is pivotal for cancer cell growth and progression. In our previous study using a conditional transgenic mouse model of breast cancer, the overproduction of hyaluronan, a major extracellular constituent, accelerated tumor angiogenesis through stromal cell recruitment. This finding led us to investigate the role of hyaluronan in the lymphatic vessel system. Here, we have found that microenvironmental hyaluronan promoted tumor lymphangiogenesis concurrently with the formation of stromal structures. Additionally, lymphatic vessels frequently penetrated and accumulated into stromal compartments, and up-regulation of vascular endothelial growth factor-C and -D was detected at tumor-stromal interfaces. To assess the contribution of stromal cells to lymphangiogenesis in vivo, we established tumor-associated fibroblasts from hyaluronan-overproducing mammary tumors and implanted them together with carcinoma cells from control tumors or MCF-7 human breast carcinoma cells in nude mice. Carcinoma cells grew rapidly in association with marked stromal reactions and lymphangiogenesis. Without the stromal cells, however, the tumors developed slowly with less stroma and lymphatic vessels. These findings underline the significance of tumor-associated stroma in the promotion of intratumoral lymphangiogenesis and suggest a pivotal role for the hyaluronan-rich tumor microenvironment.

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.

When sweating is induced by emotional or physical stimuli, the observation of the behavior of active sweat glands and measurement of the sweat rate are useful for the estimation of the degree of emotional stress on humans. When a loud sound was produced behind the subject's head, a periodical damped oscillation of sweating was observed. This sweat secretion may correlate with how a human being absorbs a big surprise stimulus. The differences of the time lag for starting to secrete sweat from sweat glands may correlate with the performance of the nervous system and/or the difference of body condition with and without stress. An intake of caffeine stimulates the central nervous system, and it rises basic, mental and thermal perspiration. The degree of physical stimuli given is amplified by the dose of caffeine, and sweating becomes 1.5–2 times greater compared to that without the dose. This study shows that sweat rate can be used as a good indicator for the state of body conditions.

The effects of photoactivation of fluorescein 5'-isothiocyanate (FITC)-dextran on lymphatic pump activity of rat mesenteric collecting vessel were studied in vivo. Rats were anesthetized with intraperitoneal alpha-chloralose and urethane, and the mesenteries were studied by using intravital videomicroscopic techniques. The diameter of the collecting lymph vessels were continuously monitored and lymphatic pump parameters (end diastolic diameter, end systolic diameter, stroke volume index, ejection fraction, contraction frequency, and pump flow index) were calculated. FITC-dextran (42 nmol/100 g body wt) without illumination caused no disturbance of lymphatic pump activity. Photoactivated FITC-dextran significantly increased end systolic diameter and decreased stroke volume index, ejection fraction, contraction frequency, and pump flow index. End diastolic diameter was not changed throughout the experiment. Superoxide dismutase (120 U/ml) and catalase (5000 U/ml) had no protective effect on photoactivated FITC-induced pump dysfunction, while histidine (singlet oxygen quencher, 10 mM) significantly prevented the disturbance of pump parameters. These results indicate that photoactivation of FITC induces negative chronotropic and negative inotropic effects in lymphatic pump activity through generation of singlet oxygen in the mesentery.

Capsaicin (5 x 10[-8] to 5 x 10[-5] M) produced a non-adrenergic and non-cholinergic phasic relaxation in a concentration-dependent manner in isolated dog urethral preparations precontracted by noradrenaline. The mode of action of capsaicin was investigated with special reference to the possible involvement of endogenous nitric oxide (NO). A marked tachyphylaxis was observed in the responses to capsaicin. Pretreatment with NG-nitro-L-arginine-methyl-ester (L-NAME) prevented or markedly reduced the inhibitory effect of L-NAME. Methylene blue inhibited the capsaicin-induced relaxation. In preparations stored at 4 degrees C for 72 h, the reduction in the capsaicin-induced relaxation was significantly greater than that in the relaxation induced by either electrical field stimulation or by sodium nitroprusside. We conclude that capsaicin produces an endogenous-NO-dependent relaxation in the isolated dog urethra via mechanisms that deteriorate during cold storage of the preparations.

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.

We studied isolated bovine mesenteric lymphatics to elucidate the pharmacological characteristics of pre- and postjunctional alpha-adrenoceptors at the sympathetic neuroeffector junction. Cylindrical strips were incubated with [3H]-noradrenaline and mounted for superfusion. Electrical stimulation (2 Hz, 0.5 msec, 50 V) augmented the fractional release of labeled noradrenaline. Exogenous noradrenaline and clonidine caused a depression of the evoked tracer release. Phenoxybenzamine and yohimbine markedly enhanced the evoked overflow of adrenergic transmitter. Rings of lymphatic vessels were mounted for isometric tension recording in organ chambers filled with Krebs-Ringer bicarbonate solution. The vessels contracted when exposed to phenylephrine and clonidine. The ED50 of clonidine was significantly lower than that of phenylephrine. Prazosin caused a parallel shift to the right of the dose-response curve to phenylephrine. The antagonist, however, suppressed the magnitude of the maximum response to clonidine. Yohimbine caused parallel shift to the right of the dose-response curves to phenylephrine and clonidine, respectively. The Schild plots for yohimbine demonstrated that the drug was a competitive antagonist to phenylephrine and clonidine. The pA2 value of yohimbine to clonidine (7.6 +/- 0.4) was larger than that to phenylephrine (6.2 +/- 0.4). The pA2 value of prazosin to phenylephrine was 7.2 +/- 0.3. These results suggest that prejunctional alpha-adrenoceptors are involved in the negative feedback mechanism for autoregulation of noradrenaline release during postganglionic sympathetic nerve stimulation, and that both alpha 1- and alpha 2-like adrenoceptors do exist on lymphatic smooth muscle cells.

The transmembrane potential and tension of the smooth muscle of isolated bovine mesenteric lymphatics were recorded in solutions having various potassium concentrations. The relation between the membrane potential and the logarithm of the external K+ concentration was observed. The maximum slope was 39 mV per 10-fold change in [K+]0. The minimum depolarization necessary for inducing contraction was 6 mV. The maximal contraction was recorded at a [K+]0 of 60 mM. In K-free solution, the membrane depolarized by about 9 mV, and the muscle developed a sustained tension. The addition of 10−5 M ouabain to normal Krebs solution caused a depolarization of the membrane and a sustained contraction. The depolarization and tension development in the K-free solution were potentiated by 10−5 M ouabain. These observations suggest that changes of membrane potential may play a major role in the activation of the contractile protein in lymphatic smooth muscle and also that there is an electrogenic sodium pump in the membrane. The depolarization and tension development in K-free solution may be due to a decreased activity of the electrogenic Na pump.

In order to evaluate the mode of action of calcitonin gene-related peptide (CGRP) on the neuroeffector mechanism of peripheral sympathetic nerve fibers, the effects of CGRP were tested on the electrical stimulated and the non-stimulated preparations of the isolated rat vas deferens. The contractile responses, which were mediated predominantly by activation of postganglionic noradrenergic nerve fibers, were dose-dependently inhibited by CGRP in concentrations ranging from 0.1 to 10 nM. The inhibitory response produced by CGRP in high concentrations ( >2 nM ) usually returned to the control level at 20–30 min and were rarely tachyphylactic. The inhibitory action of CGRP was not modified by pretreatment with 10 −7 M propranolol or 10 −7 M atropine. Contractions produced by exogenous norepinephrine (NE) and 5-hydroxytryptamine (5-HT) in unstimulated preparations were not affected by pretreatment with CGRP in a low concentration ( nM ). On the other hand, the contractions were slightly reduced 1 min after pretreatment with CGRP in high concentrations ( >5 nM ), which recovered in 15 min after constant flow washout. High concentrations of CGRP also caused a concentration-dependent relaxation on the precontracted preparations produced by high potassium (60 mM K + ) solution. These results suggest that (1) CGRP in high concentrations ( >5 nM ) may have a non-specific inhibitory action on the postsynaptic plasma membrane of the smooth muscle cell and (2) a postulated CGRP receptor exists presynaptically in the rat vas deferens and that CGRP may inhibit the release of NE during adrenergic nerve stimulation.

Histochemical studies were carried out on the distribution of adrenergic and cholinergic nerves in bovine mesenteric lymphatics. Most of the catecholamine-specific fluorescent nerve fibers demonstrated by the glyoxylic acid method encircled these vessels, although a few of them ran spirally or longitudinally. The fluorescent nerve fibers were present not only in the adventitia but also in the smooth muscle layers. The peak wavelengths of excitation and emission spectra of the fluorescence analyzed by means of a microepifluorescence spectrophotometer were about 415 and 465 nm, respectively. Both the values agreed with those of norepinephrine. Most of the cholinesterase-positive fibers stained by the copper thiocholine method were longitudinal in direction. The pattern of their distribution was similar to that of the catecholamine-containing nerve fibers, though the distribution density of the former fibers was less than the latter. Labeling was not affected by 10 −4 M iso-OMPA in the presence of acetylthiocholine iodide as a substrate—an indication that the staining of these fibers is specific for cholinesterase activity. These results suggest that the adrenergic and cholinergic nerve fibers are distributed in the smooth muscle layers as well as in the adventitia of bovine mesenteric lymphatics.

The effects of PGs (PGA2, PGB2, PGE2, PGF2 alpha, PGI2, and 6-keto PGF1 alpha) were investigated quantitatively in insolated bovine mesenteric lymphatics for elucidating the possible significance of PGs in lymph propulsion. 10(-8) M PGF2 alpha, PGA2, and PGB2 produced recognizable increases of frequency and amplitude of spontaneous contractions. The positive chrono- and inotropic responses were enhanced with increasing concentration of the PGs from 10(-8) to 10(-6) M. Both PGE2 and PGI2 in a concentration range from 10(-8) to 10(-6) M caused dose-related reductions in the amplitude of spontaneous contractions. No decrease in contraction rhythm was observed by the administration of PGI2 and PGE2 at concentrations lower than 5 X 10(-7)M. All of the above-mentioned responses induced by PGF2 alpha, PGA2, PGB2, PGI2, and PGE2 were not inhibited by pretreatment with alpha- and beta-adrenergic blocking agents, muscarinic antagonist, antihistamics, and serotonic antagonist. These findings suggest that PGF2 alpha, PGA2, and PGB2 in a low concentration may facilitate lymph flow of bovine mesenteric lymphatics in the living body, since the spontaneous contractions of lymphatic smooth muscle may drive lymph centripetally in the presence of direction valves. On the other hand, PGI2 and PGE2 may cause an inhibition of lymph transport.