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Biomedical subjects

Akira Tanaka

Publications and source records attributed to Akira Tanaka.

At least 109 records · Page 6Linked to original sources
PubMed2002

Primary hepatic carcinoid tumor with metachronous lymph node metastasis after long-term follow up.

A case of hepatic carcinoid tumor occurring in a 71-year-old man is reported. The tumor was diagnosed initially as a hepatocellular carcinoma, and was then shown after resection histologically to be a carcinoid tumor. The tumor cells formed small nests and trabeculae separated by fibrous septa and were positive for Grimelius staining. Immunohistochemically, most of the tumor cells stained positive with chromogranin A and neuron-specific enolase. After a follow up for 5 years and 7 months, the patient developed tumors in lymph nodes between the remnant liver and the lesser curvature of the stomach with no tumors in other organs. Histologically, the tumor cells in the lymph nodes demonstrated a pattern of the immunostainings consistent with carcinoid tumor. After lymphadenectomy, the patient is free from recurrence in the regional lymph nodes for more than 1 year. This case is con-sidered to be a primary hepatic carcinoid tumor with metachronous lymph node metastasis.

Aged↗
PubMed2002

Perioperative changes in carbonylhemoglobin and methemoglobin during abdominal surgery: alteration in endogenous generation of carbon monoxide.

BACKGROUND: Carbon monoxide (CO), which is homologous to nitric oxide (NO) as a monoxide, has been recently studied as a novel gaseous mediator for the maintenance of circulatory homeostasis and as a regulator of organ functions. Abdominal surgery is supposed to modulate the gaseous mediator by the reduction of heme oxygenase (HO) activity or transcriptional regulation of inducible HO. Therefore, we investigated perioperative changes in CO generation during abdominal surgery. METHODS: A total of 397 patients who received abdominal surgery under intubation anesthesia were studied retrospectively by spectrophotometric analysis of carbonylhemoglobin (COHb) and methemoglobin (metHb) in arterial blood obtained at three points: before operation; several hours after return from operation room (0 POD); and next morning (1 POD). Thirty-three splenectomies, 36 hepatectomies and 42 drainages with control of infection focus for peritonitis were compared with 286 controls. The influences of smoking and blood transfusion were disregarded in the analysis, because smoking and blood transfusion were shown to increase exogenous and endogenous CO, respectively. RESULTS: In the non-smoker control group without blood transfusion, COHb did not change during the perioperative period, while metHb increased from the preoperative value of 0.52 +/- 0.03 to 0.72 +/- 0.02 at 0 POD and returned to 0.45 +/- 0.03 mg/dL at 1 POD. In the splenectomy group, COHb decreased from the preoperative value of 1.63 +/- 0.36 to 1.19 +/- 0.20 and 1.13 +/- 0.26 mg/dL at 0 and 1 POD, respectively, as a result of the removal of the organ with high HO activity. In the splenectomy group MetHb remained low: 0.47 +/- 0.09 mg/dL at 0 POD as compared with the control value. In the peritonitis and hepatectomy groups, COHb did not change during the perioperative period, while metHb increased to 0.64 +/- 0.06 and 0.73 +/- 0.10 mg/dL at 1 POD, respectively, as compared with the control value. In the hepatectomy group with or without blood transfusion, however, COHb and metHb were higher at 1 POD than the corresponding control value. CONCLUSION: Changes in COHb and metHb concentrations in arterial blood occur during abdominal surgery, although these amplitudes are small when compared with CO intoxication and methemoglobulinemia. It is likely that organ perfusion and functions are affected by these monoxide gas mediators during abdominal surgery.

Abdomen↗
PubMed2002

DNA topology: topological transformation of DNA by reaction of cisplatin-DNA-core histone complexes with human DNA topoisomerase.

Cis-diamminedichloroplatinium(II), an active antitumor agent binds to core-histone -SV40 DNA complexes prepared by reaction of DNA with core-histone, and alters the fiber-like structure into the loosened structure. In order to model the cisplatin-modified chromatin complexes in cell, the complexes were reacted with human DNA topo II. We found the generations of unique topologically isomers such as trefoil knot (and catenane) and pseudo catenane (and pseudo knot) by reaction of cis-DDP--linearDNA--core-histone complexes with DNA topo I. The results are discussed in relation with a possible recombinational role of topo II (or topo I) on the reaction with cis-DDP--DNA--core-histone complexes.

Cisplatin↗
PubMed2002

Rapid expansion of benign scalp neurofibroma caused by massive intratumoral hemorrhage--case report.

A 62-year-old man with neurofibromatosis type 1 presented with rapid growth of a scalp mass. Head computed tomography demonstrated a large extracranial tumor of soft tissue density with massive intratumoral hematoma. Cerebral angiography demonstrated remarkable hypervascularity of the tumor. Preoperative embolization and total removal of the tumor was performed. The tumor contained a large amount of intratumoral hematoma (500 ml). The histological diagnosis was neurofibroma without malignant transformation. Benign scalp neurofibroma showing massive intratumoral hemorrhage is rare. Rapid growth or intratumoral hemorrhage in neurofibroma may be an indicator of malignant transformation.

Hemorrhage↗
PubMed2002

Aberrant right subclavian artery--three case reports.

Conventional angiography detected three cases of aberrant right subclavian artery. A 51-year-old female presented with a small infarction in the left medulla oblongata and severe stenosis of the left subclavian artery. A 59-year-old female presented with multiple cerebral infarctions and severe atherosclerotic changes in the intracranial arteries. A 58-year-old female presented with aneurysmal subarachnoid hemorrhage. The aberrant right subclavian artery was asymptomatic in all patients. Knowledge of this anatomical variation is important in diagnostic neuroangiography and interventional neuroradiology.

Aneurysm, Ruptured↗
PubMed2002

[Diet and exercise therapy of hyperlipidemia based on evidences].

Diet and exercise therapy, for which many evidences are established by many researches, are the most important in hyperlipidemic patients. In this paper, the evidences for diet and exercise therapy of hyperlipidemia were introduced and actual therapy based on the evidences was described. Regarding diet therapy, recommendable method is summarized in the table. Regarding exercise therapy, the aerobic exercise with the moderate intensity of 50% VO2max and RPE(Rate of Perceived Exertion) 11-13 is useful. The exercise more than 20 minutes and more than three times per week is necessary and the daily exercise of 30 to 60 minutes is desirable.

Diet↗
PubMed2002

[Smear-positive pulmonary tuberculosis diagnosed in a general hospital].

In Japan, patients with smear-positive pulmonary tuberculosis (SPTB) are hospitalized in a sanatorium because of the law for the prevention of tuberculosis, and not in a general hospital. According to our experience, however, some of the patients with SPTB are hospitalized in a general hospital. In order to study if it is possible to prevent the admission of patients with SPTB to a general hospital, we retrospectively reviewed and compared the medical records of pulmonary TB patients whose sputum was smear-positive for Mycobacterium tuberculosis at our outpatient clinic (Group B; n = 61), and patients whose sputum was smear-positive after the admission to our hospital (Group A; n = 17). The Group A patients were significantly older than the Group B patients [mean age, Group A, 67 years vs Group B, 56 years; (p = 0.01)]. Compared with the Group B patients, the Group A patients more often suffered from underlying diseases [percentage of patients with underlying disease, Group A, 88.2% vs Group B, 37.7%; p < 0.001]; more often showed atypical infiltrative patterns of pulmonary tuberculosis [percentage of cases showing atypical chest roentgenograms, 70.6% vs 19.7%; p < 0.001]; and were in a more serious condition [percentage of deaths during treatment, 47.1% vs 1.7%; p < 0.001]. We conclude that hospitalization of SPTB patients in general hospitals is inevitable, because SPTB can not always be accurately diagnosed before admission, and because it is sometimes difficult to send severely ill SPTB patients to a sanatorium which is inconveniently located in the countryside. We propose to provide facilities for the treatment of SPTB at all general hospitals in Japan.

Aged↗
PubMed2002

[Chronic eosinophilic pneumonia--a follow-up study of 12 cases].

In this study, twelve cases of CEP were followed for a mean period of 10.9 years (range 9.3-12.9 years) at National Himeji Hospital. Of the five women and seven men examined, two patients possessed preexisting asthma and one developed asthma during the course of CEP disease. None of the patients exhibited any symptoms of allergic rhinitis. All had dramatic responses to corticosteroid therapy without developing extrathoracic manifestations. During the course of CEP, one patient died from acute myocardial infarction. Relapses, which occurred in six patients, responded as well to the treatment as in the original episode. One patient continued long-term oral corticosteroids (5 mg/day) and steroid inhalants (800 micrograms/day) as treatment for asthma. Another was administered steroid inhalants (800 micrograms/day) to treat both asthma and relapsing CEP; two additional patients received 800-600 micrograms/day to prevent relapse. These data indicate that, with proper treatment, the long-term prognosis for patients with CEP is excellent.

Adrenal Cortex Hormones↗
PubMed1999

Suppression of T-cell function in gastric cancer patients after total gastrectomy with splenectomy: implications of splenic autotransplantation.

Background. In Japan since the 1960s, patients with gastric cancer have routinely had splenectomy combined with gastrectomy to ensure that lymph node dissection is complete. However, the influence of splenectomy on long-term immunity is unclear.METHODS: Forty-nine gastric cancer patients who underwent total gastrectomy for cure with ( n = 25) and without ( n = 24) splenectomy were assessed for immunologic function, including the proportion of lymphocyte subsets, purified protein derivative from tuberculin (PPD) response, natural killer (NK) activity, and phytohemagglutinin (PHA) response.RESULTS: Peripheral T-cell mediated functions, e.g., PPD and PHA response, were significantly suppressed in patients who underwent gastrectomy with splenectomy compared with those who had gastrectomy alone. Decreased T-cell subsets (CD 3+, 4+, 8+) and increased NK cell subsets (CD 16+, 57+) were observed in patients who underwent splenectomy. Patients who did not undergo splenectomy had immunologic responses within the normal range.CONCLUSIONS: Splenectomy decreased T-cell mediated responses over the long term. As a potential means to co-rrect this T-cell dysfunction in patients with splenectomy, splenic autotransplantation should be considered in future research.

Journal Article↗
PubMed1982

Comparative effects of acupuncture in Japan and the United States on dental pain perception.

The effect of low frequency electrical acupunctural stimulation on the perception of induced dental pain were compared in two cultural settings. Twenty Japanese and 20 American subjects (consisting of 10 Caucasians and 10 second or third generation Japanese) were tested in two functionally identical laboratories, one at Tottori University in Yonago, Japan and the other at the University of Washington. Each subject underwent a control and an acupuncture session on separate days wtih subjects counterbalanced for carry-over order effects. Sensory decision theory (SDT) analysis demonstrated a significant reduction in perceptual capability and an increased bias against reporting stimuli as painful following the acupuncture as treatment which was performed bilaterally at traditional facial points. No significant differences between groups in alteration of perceptual capability, bias or pain threshold were demonstrated, indicating that the cultural and racial differences studied did not influence responses to acupuncture in a laboratory setting.

Acupuncture Therapy↗
PubMedDate not supplied

Sensorless estimation of pressure head and flow of a continuous flow artificial heart based on input power and rotational speed.

The present study has proposed a new method for estimating the pressure head (P(t)[mm Hg]) and flow (Q(t)[L/min]) of a centrifugal pump on the basis of voltage (V(t)[V]), current (I(t)[A]), and rotational speed (N(t)[k(rpm)]) of the DC motor for a pump without any additional sensors. In the proposed estimation method, two auto-regressive exogenous (ARX) models are employed. One ARX model has an output, P(t) or Q(t), and three inputs, VI(t) = V(t)I(t) and N(t) and the steady state gain (K) of the system from VI(t) to N(t). It can be assumed that K may include the information on viscosity of blood. The coefficient parameters of this ARX model are identified in an off-line fashion before implantation of the pump. After implantation, P(t) or Q(t) is estimated by the same ARX model with the already identified parameters. The other ARX model is used to identify Kon the basis of VI(t) and N(t) in an on-line fashion every time the viscosity of blood may change. In the experiment, a mock circulatory system consisting of a centrifugal pump and a reservoir with 37% glycerin or water was employed. The root mean square error between measured Q(t) and its estimate obtained from the proposed method was 1.66L/min. On the other hand, a different method based on a single ARX model with inputs of VI(t) and N(t), but without the additional input of K, yielded the corresponding estimation error of 2.22L/min. This means that the proposed method can reduce its estimation error by about 25% in comparison with a method that cannot cope with the change in blood viscosity.

Blood Flow Velocity↗
PubMedDate not supplied

Recording vagal nerve activity for the control of an artificial heart system.

Monitoring cardiovascular control system information is important in considering the quality of life (QOL) of patients with artificial hearts. Natural heart circulation is controlled by an autonomic nervous system. Therefore, it is desirable to record autonomic nerve activity for the control of artificial heart systems. We directly recorded vagal nerve activity in long-term animal experiments. Six healthy adult goats were anesthetized with halothane inhalation, and thoracotomy was performed with the fourth rib resection during mechanical ventilation. Arterial blood pressure and right and left atrial pressures were continuously monitored with an inserted catheter. Cardiac output was measured by an electromagnetic flow meter attached to the ascending aorta. After the chest was closed, an incision was made in the left neck, and the left vagal nerve was separated. Stainless steel electrodes were inserted into the vagal nerve and fixed by a plasticizer. After the incision was closed, the goats were transferred to a cage and extubated after waking. Vagal nerve activity was measured using hemodynamic parameters when the animals were awake. Our results show that clear observation of autonomic nerve discharge was made through this experimental system for over 1 month. The tonus of the vagal nerve was significantly altered before body motion with hemodynamic changes, suggesting the possibility of prediction. These results suggest that information from autonomic nerves may help to control implantable artificial hearts or ventricular assist devices.

Animals↗
PubMedDate not supplied

Development of implantable right ventricular assist device.

Implantable ventricular assist devices (VADs) are indicated for long waiting periods before transplantation and also as a destination therapy. Meanwhile, right ventricular failure (RVF) is one of the four major complications observed in patients after left VAD (LVAD) implantation, with an incidence of approximately 20%. Preoperative prediction of the complication remains difficult, and the mortality is very high. To date, no implantable right VAD (RVAD) is available for the clinical situation. The possibility of realizing an implantable RVAD with Gyro centrifugal pump (PI-710 pump) was investigated. Eleven chronic animal experiments with LVAD and RVAD implantation were performed. Right heart bypass was established between right outflow and pulmonary trunk, and the pump was implanted in the preperitoneal space. The anatomic fit was good. The mean term of the experiments was 59 days, with excellent pump performance. Stable pulmonary hemodynamics and respiratory function were maintained during all of the experimental terms. No specific abnormal histologic findings of the lung were confirmed; however, tunica media hypertrophy was recognized in some cases. The PI-710 pump is feasible as a clinically implantable RVAD, but further study of histologic and pulmonary vascular changes after RVAD implantation is needed.

Animals↗
PubMedDate not supplied

Indirect flow rate estimation of the NEDO PI Gyro pump for chronic BVAD experiments.

In totally implantable ventricular assist device systems, measuring flow rate of the pump is necessary to ensure proper operation of the pump in response to the recipient's condition or pump malfunction. To avoid problems associated with the use of flow probes, several methods for estimating flow rate of a rotary blood pump used as a ventricular assist device have been studied. In the present study, we have performed a chronic animal experiment with two NEDO PI gyro pumps as the biventricular assist device for 63 days to evaluate our estimation method by comparing the estimated flow rate with the measured one every 2 days. Up to 15 days after identification of the parameters, our estimations were accurate. Errors increased during postoperation days 20 to 30. Meanwhile, their correlation coefficient r was higher than 0.9 in all the acquired data, and estimated flow rate could simulate the profile of the measured one.

Animals↗