Search

Introduction Acute acoustic trauma, which is a kind of sensorineural hearing loss, is caused by acoustic overstimulation. Hyperbaric oxygen therapy (HBOT) is reported to be effective against acute acoustic trauma. Objective We aimed to evaluate the efficacy of HBOT against acoustic hearing loss based on our 20 years of experience with such cases. Methods Patients who were treated with HBOT for acute acoustic trauma between April 1997 and August 2017 were evaluated in this study. Thirty-five patients with a mean age of 25.7 ± 9.2 (range: 16–48) years were included. Thirty-nine out of 70 ears (35 patients) were damaged. We investigated the initial level of hearing loss; the extent to which hearing recovered; subjective symptoms, such as tinnitus and aural fullness; and the treatment administered. Results The planned HBOT was completed in 37 of 39 ears. Twenty-six of the 37 ears (70.2%) displayed improved hearing, and 31 of the 37 ears (83.9%) exhibited symptom improvement. Twenty-three (76.7%) and 26 (86.7%) of the 30 ears treated with steroids demonstrated improvements in hearing and subjective symptoms, respectively. Conclusion A combination of HBOT and steroids should be considered as a treatment for acute acoustic trauma in cases involving symptoms such as tinnitus and aural fullness.

Divers, pneumatic construction workers, aviators, and astronauts sometimes suffer decompression illness (DCI). DCI includes decompression sickness (DCS) and arterial gas embolism (AGE) and is treated with recompression therapy. Etiology of DCS is highly related with micro bubbles formed in the body fluid. AGE is caused by pulmonary over inflation-induced rupture of the alveoli. Recompression therapy is a kind of hyperbaric oxygen therapy, for which U.S. Navy treatment tables are widely used. The purposes of recompression therapy are (1) to reduce volume of the bubbles in the body, (2) to increase absorption of the bubbles in the body fluid and exhalation of inert gases from the lung, and (3) to increase oxygen supply via plasma to the cells in peripheral tissues. Recompression therapy has other beneficial effects, such as anti-inflammatory, wound healing, and anti-infectious effects. During the evacuation of the DCI patient to an appropriate facility, to continue administration of 100% oxygen and not to decrease environmental pressure are both critical for stabilizing the patients’ condition. It is important for all physicians who have a chance to treat DCI patients to be versed in mechanisms of recompression therapy and handling the treatment tables.

The effects of short-term simulated microgravity on the lymph dynamics of rat lymph nodes were investigated using a combination of Bollman's cage and head-down tilt (HDT). Efferent lymphatics of the iliac and mesenteric lymph nodes were cannulated for the collection of lymph. There was no significant difference in lymph flow rate from the iliac lymph nodes between non-HDT (control) and HDT rats. Lymph flow rate from the mesenteric lymph nodes in HDT rats was slightly higher than that obtained with the control. The cell count obtained from the iliac lymph nodes in HDT rats was significantly larger than those of the controls, while no significant difference in the number of cells from the mesenteric lymph nodes was observed between the control and HDT groups. The cells from the iliac lymph nodes in the control and HDT rats were mostly lymphocytes. The distribution of subsets of lymphocytes (CD3+, CD4+, CD8a+, and CD45R+) from the iliac lymph nodes in HDT rats was not significantly different from the subsets of lymphocytes in the control. Immunization did not affect the distribution of lymphocyte subsets from the iliac lymph nodes in the control and HDT groups. There was no significant difference in the concentrations of lymph albumin in iliac afferent or efferent lymphatics between the control and HDT groups. These findings suggest that HDT posture in Bollman's cage induces transient output of lymphocytes from the iliac lymph nodes of rats in vivo without changing the flow rate, lymphocyte subsets, or concentration of albumin.

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.

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.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.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.

Lymphatics are a unidirectional transport system that carries fluid from the interstitial space and back into the blood stream. Initial lymphatics take up not only fluid but also high-molecular-weight substances, such as plasma proteins and hyaluronan; immune cells, such as lymphocytes, macrophages, and dendritic cells; and colloidal particles, such as carbon particles, bacteria, and tattoo dye. Interstitially injected colloidal particles are known to accumulate in the regional lymph nodes. This phenomenon is applied to find sentinel lymph nodes in cancer patients. Lymph flow rate and composition are influenced by interstitial fluid, lymphatic pump activity, and intra-lymphatic pressure. Lymph composition is changed during its flow downstream. In this review, the main focus is on the mechanisms of lymph formation at the initial lymphatics and lymph transport through the collecting lymphatics and lymph nodes. (*English Translation of J Jpn Coll Angiol, 2008, 48: 113-123.).

Molecular mechanisms of reconnection of collecting lymph vessels were analyzed by using murine popliteal prenodal lymph vessels. At 1 and 2 weeks after being divided by cutting the lymph vessel, lymphatic reconnection was frequently observed accompanied by mesh-like lymphatic channels. Electron microscopic study also showed a monolayer of endothelial cells in the newly developed lymph vessels. Smooth muscle markers were immunofluorescently demonstrated in the wall of the new vessels. At 1 week after the procedure of cutting, augmented expressions of VEGF receptors 1, 2 and 3 were found immunohistochemically at the site of the reconnected lymph vessels. The expression of mRNA for VEGF receptor 3 was enhanced at 5 days and 1 week in small pieces of the tissues containing the reconnected lymph vessels, compared with that in the corresponding tissues obtained with sham operated ones. The administration of VEGF-C at the cutting site of the collecting lymph vessel significantly increased the rate of the reconnected lymph vessels, whereas additional treatment with Flt4/Fc chimera protein significantly reduced the rate of the reconnected ones. These results suggest that activation of VEGF-C-VEGF receptor 3 has critical roles in reconnection of the collecting lymph vessels in adult mice.

This study was designed to examine whether mature collecting lymphatics can regenerate in the adult tissue or not.The X-ray lymphograms were used to detect network of the collecting lymphatics in rabbit hind leg. Regeneration of the lymphatics was observed after surgical removal of the popliteal lymph node or a part of the popliteal afferent lymphatic. Structure and mechanical properties of the lymphatics were also examined by light and electron microscopes and in vitro functional experiments.One week after removal of the lymph node, only an afferent lymphatic and a deposit of the contrast medium at the popliteal region were observed. Four weeks after the removal, the connection of the afferent and efferent lymphatics at the popliteal region, and collateral lymphatics were present in the leg. Further, 4 weeks after 1-mm excisions of a part of the lymphatic, recanalization was observed between the central and peripheral cut ends of the lymphatic but not after 3- and 10-mm excisions. Endothelial cells and smooth muscle cells could be observed by electron microscope, and contractile proteins, and alpha-smooth muscle actin SM1 and SM2 were immunofluorescently detected in both intact and the regenerated lymphatic walls. In both lymphatics, norepinephrine and acetylcholine induced dose-dependent constriction and dilation of the vessels, respectively.The present study demonstrated that mature collecting lymphatics are able to regenerate in the adult tissues.

The electrical stimulation-induced responses of isolated dog thoracic ducts were investigated using an organ bath technique. Electrical stimulation (0.7 ms in pulse width, 25 V in nominal voltage, 10 s in duration time, 1–32 Hz at frequency) produced frequency-related contractions in the lymphatic preparations. The contractions were abolished by pretreatment with tetrodotoxin (10 −7 M), guanethidine (10 −7 , 10 −6 M), and bretylium (10 −7 , 10 −6 M). Cocaine (10 −6 M) significantly potentiated the electrical stimulation−induced contractions. Phentolamine (10 −8 –10 −5 M), prazosin (10 −8 –10 −5 M), bunazosin (10 −6 , 10 −5 M), yohimbine (10 −8 –10 −6 M) and rauwolscine (10 −8 –10 −6 M) also dose−dependently reduced the contractions. On the other hand, propranolol (10 −8 –10 −6 M), atropine (10 −6 M), hexamethonium (10 −6 M), aspirin (3×10 −5 M), Nω -nitro- l -arginine methyl ester (L-NAME) (3×10 −5 M) and L-NAME (3×10 −5 M)+ l -arginine (10 −4 M) caused no significant effect on electrical stimulation-induced contractions. No significant difference in the electrical stimulation-induced responses was observed between the lymphatic preparations with and without an intact endothelium. The electrical stimulation caused only a small contraction with no relaxation in the thoracic duct preparation precontracted with 10 −8 M U46619. The small contraction was abolished by 10 −5 M phentolamine. These findings suggest that there exists α 1 - and α 2 -adrenoceptors-mediated excitatory innervation, but no NO-ergic inhibitory nerve fiber in dog thoracic ducts.

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.