Learning to stop: a unifying principle for legged locomotion in varying environments.

Evolutionary studies have unequivocally proven the transition of living organisms from water to land. Consequently, it can be deduced that locomotion strategies must have evolved from one environment to the other. However, the mechanism by which this transition happened and its implications on bio-mechanical studies and robotics research have not been explored in detail. This paper presents a unifying control strategy for locomotion in varying environments based on the principle of 'learning to stop'. Using a common reinforcement learning framework, deep deterministic policy gradient, we show that our proposed learning strategy facilitates a fast and safe methodology for transferring learned controllers from the facile water environment to the harsh land environment. Our results not only propose a plausible mechanism for safe and quick transition of locomotion strategies from a water to land environment but also provide a novel alternative for safer and faster training of robots.

An anthropomorphic soft skeleton hand exploiting conditional models for piano playing.

The development of robotic manipulators and hands that show dexterity, adaptability, and subtle behavior comparable to human hands is an unsolved research challenge. In this article, we considered the passive dynamics of mechanically complex systems, such as a skeleton hand, as an approach to improving adaptability, dexterity, and richness of behavioral diversity of such robotic manipulators. With the use of state-of-the-art multimaterial three-dimensional printing technologies, it is possible to design and construct complex passive structures, namely, a complex anthropomorphic skeleton hand that shows anisotropic mechanical stiffness. We introduce a concept, termed the "conditional model," that exploits the anisotropic stiffness of complex soft-rigid hybrid systems. In this approach, the physical configuration, environment conditions, and conditional actuation (applied actuation) resulted in an observable conditional model, allowing joint actuation through passivity-based dynamic interactions. The conditional model approach allowed the physical configuration and actuation to be altered, enabling a single skeleton hand to perform three different phrases of piano music with varying styles and forms and facilitating improved dynamic behaviors and interactions with the piano over those achievable with a rigid end effector.

Frequent loss of heterozygosity in the region including BRCA1 on chromosome 17q in squamous cell carcinomas of the esophagus.

Ninety-four esophageal squamous cell carcinomas were examined for loss of heterozygosity at several loci on the long arm of chromosome 17 (17q), using restriction fragment length polymorphism markers. Loss of heterozygosity was observed in 56 (62%) of 91 tumors that were informative with at least one marker. Comparison of these results with clinicopathological data indicated that the losses on chromosome 17q had occurred at an early stage of carcinogenesis. Detailed deletion mapping in these tumors revealed that the region commonly deleted was within the segment between loci defined by two markers at chromosomal band 17q21.3.

Assessment of protein kinase C isozymes by enzyme immunoassay and overexpression of type II in thyroid adenocarcinoma.

A two site enzyme immunoassay which quantitatively identifies types I, II, and III of protein kinase C isozymes has been designed. The soluble protein kinase C isozymes were selectively immobilized by type-specific monoclonal antibodies, MC-1a, -2a, and -3a (H. Hidaka et al., J Biol. Chem., 263: 4523-4526, 1988) which bind to the regulatory domain (NH2-terminal side) of protein kinase C. The amount of each isozyme was then determined using a horseradish peroxidase-conjugated polyclonal antibody raised against the COOH-terminal peptide of protein kinase C. By adding increasing concentrations of the antigen, the range of the assay proved to be 0.51-51, 0.081-8.1, and 0.31-31 nM for types I, II, and III, respectively. This sandwich method was used to determine the level of protein kinase C isozymes in rabbit tissues. Type I was mainly present in the cerebrum and cerebellum; the highest amount of type II isozyme was present in blood platelets [26.0 +/- 3.8 (SE) micrograms/g wet tissue]. We compared the protein kinase C isozyme levels in human normal thyroid gland and thyroid cancer tissues and found that type II protein kinase C specifically increased in thyroid cancer tissues. Immunocytochemical examination using MC-2a revealed that the cytoplasm of the cancer cells showed prominent immunoreactivity for type II isozyme.

Goal-directed multimodal locomotion through coupling between mechanical and attractor selection dynamics.

One of the most significant challenges in bio-inspired robotics is how to realize and take advantage of multimodal locomotion, which may help robots perform a variety of tasks adaptively in different environments. In order to address the challenge properly, it is important to notice that locomotion dynamics are the result of interactions between a particular internal control structure, the mechanical dynamics and the environment. From this perspective, this paper presents an approach to enable a robot to take advantage of its multiple locomotion modes by coupling the mechanical dynamics of the robot with an internal control structure known as an attractor selection model. The robot used is a curved-beam hopping robot; this robot, despite its simple actuation method, possesses rich and complex mechanical dynamics that are dependent on its interactions with the environment. Through dynamical coupling, we will show how this robot performs goal-directed locomotion by gracefully shifting between different locomotion modes regulated by sensory input, the robot's mechanical dynamics and an internally generated perturbation. The efficacy of the approach is validated and discussed based on the simulation and on real-world experiments.

Protective effect of the thromboxane A2 receptor antagonist ONO 3708 on ischemia-reperfusion injury in the dog liver.

BACKGROUND: Prostaglandins are widely known to have cytoprotective effects in a variety of conditions. Thromboxane A2 has the opposite effect of prostaglandins. In this study the effects of the thromboxane A2 receptor antagonist ONO 3708 on ischemia and subsequent reperfusion in the dog liver was evaluated. METHODS: Mongrel dogs weighing from 10 to 15 kg were divided into three groups: a control group, a group with induced liver ischemia and subsequent reperfusion, and a group that received ONO 3708 and then underwent induced liver ischemia and subsequent reperfusion. Liver ischemia was induced by the Pringle procedure for 60 minutes. The concentrations of total free amino acids, aromatic amino acids, and branched-chain amino acids in blood taken from the portal and hepatic veins were examined before and after the Pringle procedure in the latter two groups and at the corresponding points in the control group. RESULTS: Disturbances in amino acid metabolism in the liver occurred 5 minutes after the declamping in the ischemic group, and prostaglandin I2 and thromboxane A2 levels and lipid peroxide production, were increased. In contrast, hepatic amino acid metabolism was unchanged, and prostaglandin I2 and thromboxane A2, and lipid peroxide production, were normalized in the group that was treated with ONO 3708. CONCLUSIONS: ONO 3708 appears to protects hepatic tissue from ischemia-reperfusion injury through free-radical scavenging, by increasing prostaglandin I2 levels, and by decreasing thromboxane A2 production.

A case report on successful removal of intravenous leiomyomatosis extending in the right ventricle.

A patient with intravenous leiomyomatosis arising from the uterus and extending in the heart and lower extremity was successfully treated with a two-stage operation. A new technique with a polypectomy snare is described.

Clinical evaluation of upper mediastinal dissection for differentiated thyroid carcinoma.

BACKGROUND: An extensive upper mediastinal dissection in advanced differentiated thyroid carcinoma is occasionally required. This investigation was undertaken to clarify the indications for mediastinal lymph node dissection and the route of upper mediastinal metastases. METHODS: Twenty-one patients with differentiated thyroid cancer, who underwent their first radical operations with mediastinal dissection through a partial midline sternotomy, were enrolled in this study. Of 21 patients, 10 (48%) were found to have mediastinal lymph node metastases. RESULTS: The tumor size in the group with metastatic disease was much bigger than that in the group without metastatic disease. Histologic type and age were similar between the two groups. The extent of cervical lymph node metastases was more significant in the group with metastatic disease; in particular, all 10 patients showed more than two metastatic nodes along the internal jugular vein of the tumor-free side. CONCLUSIONS: This study indicates that metastases to the internal jugular chain on the side contralateral to the primary tumor would be an extremely important factor for indication of extensive upper mediastinal lymph node dissection after median partial sternotomy in patients with differentiated thyroid carcinoma.

Frequent natural killer cell abnormality in children in an area highly contaminated by the Chernobyl accident.

Since January 1991, we have been performing thyroid surveys and hematologic and immunologic screening on children in Chechersk, Belarus, a city situated in one of the areas most seriously contaminated with high levels of radionuclides after the Chernobyl accident. Ten children selected from 713 children because of goiter did not show a decrease in humoral immunity or in the number and function of T cells. By contrast, natural killer (NK) cell activity against K562 cells was depressed in 4 of these 10 children. The clinical and laboratory findings indicated that previously reported diseases with NK cell dysfunction could be excluded. A comparative analysis of NK cell activity in children from areas with and without high 137Cs levels revealed a high frequency of abnormal NK cell activity only in children from the area contaminated by radioactive fallout. In addition, there was no correlation between NK cell activity and NK cell number as percentage in the children from the area with high 137Cs levels. Neither activity nor number of NK cells was correlated with the body content of 137Cs. Thus, the frequent abnormality of NK cell function may not have been due to actual internal exposure to the long-lived radionuclide.

Suppressive effect of ulinastatin on plasma fibronectin depression after cardiac surgery.

Plasma fibronectin, an opsonic glycoprotein, is known to modulate the reticuloendothelial phagocytic clearance of nonbacterial and, possibly, bacterial particulates. The decreased plasma fibronectin levels seen after cardiac surgery have been considered to derive mainly from opsonic consumption. In the present study, we demonstrated that the administration of ulinastatin, a human urinary trypsin inhibitor, to patients after cardiac surgery not only inhibited the postoperative depression of plasma fibronectin levels, but also maintained the plasma fibronectin level within the normal range. This effect apparently resulted from the inhibitory activity of ulinastatin on the proteolytic enzymes released after operation. This result suggests that the decreased plasma fibronectin level noted after cardiac surgery may derive mostly from excessive proteolytic enzymes. Our observation also indicates that the prophylactic administration of ulinastatin to patients undergoing major operations will result in a favorably functional reticuloendothelial phagocytic system.

Adjuvant radiotherapy after complete resection of thymoma.

Seventy patients were studied after undergoing complete resection of thymoma to determine the effect of postoperative adjuvant mediastinal radiotherapy on prognosis, with regard to clinical stage, histological type, and pleural factor. Pleural factor was defined as follows: p0, no adhesion to the mediastinal pleura; p1, fibrous adhesion to the mediastinal pleura without microscopic invasion; and p2, microscopic invasion of the mediastinal pleura. Recurrence of thymoma after complete resection was observed in 13 patients, 12 (92%) with pleural dissemination, 6 (46%) with local recurrence, and 2 (15%) with distant metastasis (types of recurrence are overlapping). In stage I and stage II p0 patients, no recurrence was observed, regardless of mediastinal radiotherapy. Whereas mediastinal irradiation completely prevented recurrence in stage II p1 patients, 4 (36.4%) nonirradiated stage II p1 patients experienced recurrence. In stage II p2 patients, 75% had pleural dissemination even after radiotherapy. A high incidence of recurrence was also observed in stage III, nonirradiated (25%) and irradiated (30%) patients. The results suggest that mediastinal irradiation for stage I and II p0 patients is not always necessary, and that therapy for stage II p1 is essential and also expected to decrease the recurrence rate. On the other hand, in stage II p2 and stage III thymomas, mediastinal irradiation is not sufficient to prevent pleural recurrence even after complete resection. Our classification based on pleural factor is useful for better selection of appropriate postoperative treatment for thymoma patients.

Platysma musculocutaneous flap for reconstruction of trachea in esophageal cancer.

In 2 patients with advanced cervical esophageal cancer invading the trachea, total laryngoesophagectomy with resection of the posterior portion of the trachea and lymph node dissection of the bilateral neck and superior mediastinum was carried out. The partial defect in the trachea was repaired with a platysma musculocutaneous flap. A permanent tracheostoma, composed of the tracheal remnant anteriorly and the platysma musculocutaneous flap posteriorly, was made just over the manubrium sterni.

Enhanced sensitivity of pancreatic cells to cholecystokinin octapeptide in obstructive jaundice.

Exocrine function of the pancreas in obstructive jaundice was examined using dogs. Jaundice induced by choledochal ligation over 3 weeks showed pancreatic hypersecretion in response to cholecystokinin octapeptide (CCK-8) stimulation. To clarify the mechanism of pancreatic hypersecretion in obstructive jaundice, three experiments were undertaken. In a perfusion experiment performed on isolated pancreas, hypersecretion in obstructive jaundice was observed in response to CCK-8 stimulation. An incubation experiment showed an increase in secretion in response to CCK-8 stimulation in a dose-dependent manner, producing a greater increase in dogs with obstructive jaundice than in controls, despite the fact that basal secretion in both groups was the same. This would suggest that at least one of the mechanisms of pancreatic hypersecretion in obstructive jaundice may be related to the degree of sensitivity of acinar cells to CCK-8. In morphological observation of acinar cells by electron microscopy, the average number of zymogen granules and total granular area per unit of cytoplasm in both groups before and after stimulation with CCK-8 were compared. There was no difference between the groups before stimulation. Following stimulation, values for the control group decreased but appeared to increase in the jaundiced pancreas. These results strongly suggest that pancreatic acinar cells in obstructive jaundice may retain their secretory potential after stimulation for 60 min, though the potential in nonjaundiced pancreatic acinar cells may decrease after stimulation.

Metabolism of insulin and glucagon in liver and pancreas in dogs with obstructive jaundice.

Insulin and glucagon metabolism in the pancreas with obstructive jaundice caused by complete ligation of the common bile duct and in the cholestatic liver caused by hepatic duct ligation was evaluated experimentally using dogs. The isolated perfused pancreas in obstructive jaundiced dogs, which showed a low insulin response in the peripheral blood after intravenous glucose administration, revealed depression of insulin production and no change of glucagon production in response to cholecystokinin octapeptide. The extraction of insulin in the cholestatic lobe of the liver was decreased compared with that in the noncholestatic lobe. The extraction of glucagon, on the other hand, in the cholestatic lobe and in the noncholestatic lobe showed no significant difference. So the imbalance of glucose metabolism in obstructive jaundice does not depend on the enhanced extraction of insulin in the liver, but on the depression of insulin production in the pancreas.

Effects of parathyroid hormone on pancreatic exocrine secretion.

The role of parathyroid hormone (PTH) and calcium on pancreatic exocrine secretion were observed using sham-operated and parathyroidectomized dogs. First, exocrine secretion of the pancreas stimulated with secretin and cholecystokinin octapeptide (CCK-8) was examined in vivo 3 weeks after parathyroidectomy. Secondly, perfusion experiments of isolated pancreas in the sham-operated and parathyroidectomized dogs were examined. In one experiment, volume of pancreatic juice and bicarbonate output, but not amylase output, was decreased in the parathyroidectomized dogs compared with those in the sham-operated dogs; no participation of calcium in exocrine secretion was revealed. In another experiment, high doses of PTH evoked increases of pancreatic juice and bicarbonate output without changing amylase output; as before, no participation of calcium in the exocrine secretion was observed. We conclude that (a) PTH increases volume of pancreatic juice and bicarbonate output, and (b) pancreatic exocrine secretion is modified by direct effect of PTH, and the pancreatic ductular cells, not the acinar cells, are the target for PTH.

Evaluation of imaging examination for hepatic invasion of carcinoma of the gallbladder and postoperative patient outcome.

BACKGROUND: Hepatic invasion is an important factor in the selection of an operative procedure for patients with carcinoma of the gallbladder. Imaging modalities to detect the hepatic invasion were evaluated for accuracy, and postoperative patient outcome was analyzed. STUDY DESIGN: Thirty-six patients who were treated for carcinoma of the gallbladder at our institution between 1984 and 1993 were studied. The imaging results of ultrasonography (US), computed tomography, and angiography were compared with histologic findings regarding intrahepatic invasion of the carcinoma. RESULTS: Histologic examination of the operative specimens removed from 21 patients revealed that the detection of hepatic invasion with preoperative US was superior to that with the other two modalities. The preoperative US showed a diagnostic value that was almost the same as that of the intraoperative US. The postoperative patient outcome was not satisfactory, although extended radical operation was performed using image guidance in the 21 patients. The patients died as a result of nodal recurrence rather than hepatic recurrence. CONCLUSIONS: Preoperative US should be performed initially for detecting hepatic invasion from carcinoma of the gallbladder and can be substituted for intraoperative US. Considering the operative treatment for patients with carcinoma of the gallbladder, lymph node dissection is as important as the extent of hepatectomy.

Management of chylothorax after pulmonary resection.

BACKGROUND: Conservative management with intrapleural drainage and total parenteral nutrition (TPN) has been the first choice of treatment for postoperative chylothorax. With this approach, however, it usually takes several weeks for the chylothorax to resolve and it is sometimes unsuccessful. In this study, we reviewed seven patients who had chylothorax develop after pulmonary resection for primary carcinoma of the lung. STUDY DESIGN: The patients were treated according to a "one-week trial" that consisted of one week of observation with intrapleural drainage and maximum parenteral nutritional support followed by operative intervention if the effect of the conservative therapy was not adequate. When the chylous leak was decreased to less than 100 mL/day or less than 15 percent of the maximum daily drainage volume after the "one-week trial," the conservative management was continued for two more weeks. After observation for three weeks, oral intake was begun and a final evaluation of the treatment was made. RESULTS: One patient did not consent to the "one-week trial" and underwent operative treatment on the third postoperative day. Two patients had chylous leaks less than 100 mL/day or less than 15 percent of the maximum daily chylous leak after one week observation. Conservative management with TPN was continued in these patients for two more weeks and operation was performed in one on the 20th day and in the other on the 22nd postoperative day. The remaining four patients underwent operative treatment on the seventh or eighth postoperative day. All of the operations for chylothorax were successful, and chest tubes were removed promptly. These results show that operative management of chylothorax was reliable and safe. The "one-week trial," however, offered few advantages in determining the therapeutic strategy for postoperative chylothorax.

Significance of values of thyrotropin binding inhibitor immunoglobulins and appearance of intrathyroidal lymphocytes at subtotal thyroidectomy for Graves' disease.

This study was undertaken to investigate whether thyrotropin binding inhibitor immunoglobulins (TBII) values at and after subtotal thyroidectomy correlated with the outcome or the histologic grade applied to the appearance of intrathyroidal lymphocytes at the time of surgical treatment. In addition, the main reason for the study was to determine whether or not it was possible to predict the outcome after the operation by the data obtained. There was no relation between the TBII results and the grade of the appearance of intrathyroidal lymphocytes at the time of operation or the TBII postoperative results (whether positive or negative) and the final outcome. However, it was of interest that patients with a recurrence of hyperthyroidism had the TBII values of more than 50 percent at the time of surgical treatment, and also manifested continuously positive TBII values after the operation. They also had moderate grades of lymphocytic infiltration and lymph follicle formation in the surgical specimen. It seemed impossible to predict the outcome of each instance in accordance with TBII values and the grade of the appearance of intrathyroidal lymphocytes at the time of the operation. However, it might be possible to predict at least the recurrence of hyperthyroidism by the consideration of changes of TBII values postoperatively.

Thyroid abnormalities among children in the contaminated area related to the Chernobyl accident.

Gradual increases of various radiation-related diseases including thyroid cancer following the Chernobyl accident have been recently reported. We have carried out systematic thyroid surveys in school children aged 10-15 years in the highly contaminated area and compared the results with a similar survey in a nonaffected neighboring area as a control. Systematic examinations of the thyroid gland were performed in 888 schoolchildren (408 males and 480 females) in the districts of Chechelsk city with 5 to over 40 Ci/km2 of radiation level for 137Cs. In the control area (Bobruisk city), 521 children with the same age range (229 males and 292 females) were examined. Thyroid surveys were carried out as follows: palpation, ultrasonography, blood examinations of thyroid function, and measurements of daily urinary excretion of iodine. Certain thyroid abnormalities were observed in the high radioactive fallout area more frequently than in the control region. In particular, the prevalence of multiple micronodular lesions in diffuse goiter in the contaminated area was significantly higher than in the control area. However, endemic goiter due to iodine deficiency was present in both districts. The environment factor of iodine deficiency might have resulted in the early occurrence of ultrasonographic thyroid abnormalities attributed to radioactive contamination.

Immunohistochemical studies on local antitumor effects of streptococcal immunopotentiator, OK-432, in human solid malignant tumors.

Immunocytochemical techniques were used to clarify the local inhibitory effects of a streptococcal immunopotentiator, OK-432, against solid malignant tumor growth. Natural killer (NK) cells and fibronectin were chosen as immunostaining markers to demonstrate the antitumor effects. Immunocytochemical staining was performed by the avidin-biotin-peroxidase complex method. These investigations demonstrated that (1) local administration of OK-432 seems to promote a marked induction of NK cells and fibroblasts around or entering into the cancerous lesions and (2) the cancer cell-killing effect of NK cells and the fibronectin-enriched stromal reaction augmented by the injection of OK-432 suggest at least the possibility of protection against neoplastic growth with invasion and the spread of distant or nodal metastases of solid carcinomas.