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Biomedical subjects

K Matsuda

Publications and source records attributed to K Matsuda.

At least 919 records · Page 51Linked to original sources
PubMed1966

The effects of external sodium and potassium concentration on the membrane potential of atrioventricular fibers of the toad.

Intracellular records were made from fibers in the A-V conducting system of isolated toad hearts. The A-V region was perfused with Ringer's solution of various K and Na concentrations. Resting potential in 2.8 mM [K]o was about 60 mv. Over the range 0.28 to 28 mM, resting potential diminished with increasing [K]o. Spontaneous action potentials appeared when [K]o was increased to 11.2 mM, and when resting potential had fallen to about 40 to 50 mv. Changes in [Na]o over the range 22 to 110 mM had a little effect on resting potential, but there was a linear relation between the peak value of the action potential and log [Na]o. Wenckebach periodicity was observed when [Na]o was lowered.

Action Potentials↗
PubMedDate not supplied

Virological significance of HBeAg subtypes (HBeAg/1 and HBeAg/2) in patients with type B hepatitis.

In order to establish the virological significance of HBeAg subtypes (HBeAg/1 and HBeAg/2) during hepatitis B virus infection, HBsAg, HBeAg and hepatitis B virus DNA in serum and HBcAg in liver were determined quantitatively in relation to the detection of HBeAg subtypes in agar gel diffusion. Thirty-eight chronic HBsAg carriers with HBeAg, including 16 non-specific reactive hepatitis, 8 chronic persistent hepatitis, 11 chronic active hepatitis and 3 liver cirrhosis, who were seen at Tohoku University Hospital from 1983 to 1985, were examined. Significantly larger amounts of HBsAg, HBeAg and hepatitis B virus DNA in serum and HBcAg in liver were found in patients positive for both HBeAg/1 and HBeAg/2 in serum than in those positive for only HBeAg/1 or negative for both subtypes. These results suggest that the presence of HBeAg/2 in serum may reflect the occurrence of active viral replication. When the detection pattern of HBeAg subtypes was examined during serial follow-up for at least 1 year, three groups of patients were classified with respect to the presence of HBeAg/2, i.e., Type I, consistently positive for HBeAg/2; Type II, consistently negative for HBeAg/2, and Type III, intermittently positive for HBeAg/2. More than 80% of Type I patients were histologically diagnosed having as nonspecific reactive hepatitis, while more than 80% of Type II and III patients had more progressive liver diseases such as chronic persistent hepatitis, chronic active hepatitis and liver cirrhosis. These results suggest that the serial examination of HBeAg subtypes in serum may be important for more detailed evaluations of type B hepatitis.

Adult↗
PubMedDate not supplied

Plasma glucagon in insulinoma.

Nine patients with insulinoma were studied in order to investigate glucagon levels in the fasting state and the response of plasma glucagon to tolbutamide and arginine. Fasting plasma glucagon levels were within the normal range in all patients except two cases with malignant insulinoma. Although there was no correlation between blood glucose and plasma glucagon, a significant correlation between plasma glucagon and plasma insulin was observed. No detectable changes were found in glucagon levels during tolbutamide injection. In almost all patients except one an exaggerated response of plasma glucagon was demonstrated during arginine infusion test.

Adenoma, Islet Cell↗
PubMedDate not supplied

A bilayer "artificial skin" capable of sustained release of an antibiotic.

The most frequent complication of the bilayer "artificial skin", composed of a silicone sheet and collagen sponge described in a previous paper, was infection beneath it. This paper describes a new type of "artificial skin" in which microspheres containing antibiotics were installed beneath the silicone sheet, allowing a continuous release of antibiotics.

Adult↗
PubMedDate not supplied

Novel mechanical assistance in the treatment of endotoxic and septicemic shock.

Systemic sepsis is a frequent and fatal complication of postoperative patients. More recently, therapeutic trials of plasma or blood exchange are performed in septic patients for the purpose of reducing both endotoxins and albumin-bound toxins. As an alternate approach such as this for the removal of endotoxin directly from the blood, the authors recently developed polymyxin B immobilized fiber (PMX-F) as a biomaterial for selectively detoxifying endotoxin. That this newly invented PMX-F neutralizes a sufficient amount of endotoxin in vitro was reported previously. In ex vivo experiments, direct hemoperfusion by PMX-F was performed on purified endotoxin injected canine and on live Escherichia coli induced septic dogs. Only 5% (1/20) survived in the control group, but 75% (30/40) survived in the treated group. Septic dogs died within 18 hours after bacteria infusion in the control group. But all in the treated group survived 3 days. Forty percent of them survived permanently. These observations indicate that PMX-F treatment, namely selective removal of endotoxin in the endotoxic and septicaemic dogs prolongs or increases the chances of survival. Blood compatibility of PMX-F was also evaluated both in vitro and in vivo. With platelets it was shown to be fairly good and with red blood cells, white blood cells, and proteins, extremely good. A preclinical study on the efficacy and safety of PMX-F throughout widespread experiments has just ended.

Animals↗
PubMedDate not supplied

The efficiency of new leukocyte removal filters. CF-1 and CF-2.

Two new leukocyte removal filters, Nipro CF-1 and CF-2 (Nipo Medical Industries, Osaka, Japan), were evaluated. These non-woven polyester filters, which are gravity flow devices that require no priming and no rinsing after use, were developed for preparing 400 ml of whole blood or red cell concentrates from 400 ml of whole blood. A flow cytometric technique was developed to measure extremely low white blood cell (WBC) counts. To evaluate the efficiency of these filters, leukocyte counts were measured by three techniques: 1) electronic, 2) visual, and 3) flow cytometry. Flow cytometric counting was done using a Coulter EPICS-C cytometer (Coulter Corp., Hialeah, FL). Nipro CF-1 removed 99.97 +/- 0.01% (mean +/- SD, n = 14) of leukocytes measured by flow cytometry, and CF-1 recovered 90.7 +/- 4.47% (n = 21) of red blood cells. After filtration through CF-2, more than a 6 log10 (> 99.9999%) depletion of WBCs was detected in six samples, a 6 log10 (99.9999%) depletion of WBCs was detected in two samples, a 5 log10 (99.999%) depletion was detected in five samples, and a 4 log10 (99.99%) depletion was detected in one sample. CF-1, in which size and priming volume was smaller than other commercial leukocyte removal filters, accomplished a 3 log10 reduction in WBC count, compared with other commercial filters. CF-2 achieved a 4-6 log10 depletion of WBCs assayed by flow cytometry.

Blood Transfusion↗
PubMedDate not supplied

Hepatic circulation during nonpulsatile cardiopulmonary bypass.

The arterial ketone body ratio, which reflects the hepatic mitochondrial redox potential (NAD+/NADH), decreases markedly during cardiopulmonary bypass (CPB). One of the reasons for arterial ketone body ratio reduction may be hepatic hypoperfusion during CPB. To evaluate the hepatic circulation under nonpulsatile CPB, the authors used color Doppler ultrasonography to measure the portal venous flow (PVF) in 24 adult patients before, during (aortic clamping and rewarming period), and after CPB. Nonpulsatile hypothermic CPB was performed at a flow rate of 2.4 L/min/m2. PVF was calculated from the product of mean flow velocity and cross-sectional area of the portal vein. PVF was maintained during CPB at 0.44 +/- 0.13 and at 0.54 +/- 0.18 L/min/m2. PVF (%) in relation to systemic blood flow was obtained by calculating PVF/CI or PVF/PI, where CI is the cardiac index and PI is the perfusion index. PVF (%) before, during, and after CPB was 18.3 +/- 9.3, 18.5 +/- 5.5, and 17.4 +/- 6.7%, respectively. In conclusion, PVF was maintained during nonpulsatile CPB at a flow rate of 2.4 L/min/m2 and depended upon systemic blood flow.

Adult↗
PubMedDate not supplied

Applicability of the latissimus dorsi muscle in situ as a biomechanical energy source.

The purpose of this study was to assess the applicability of the latissimus dorsi muscle in situ as an energy source for a circulatory assist device. A pneumatic chamber, devised by the authors, was inserted beneath the muscle and compressed by contractions of the muscle so that muscle contractile power was converted into pneumatic pressure. The optimal insertion position of the chamber beneath the latissimus dorsi muscle, and the influence of chamber size on generated pneumatic pressure, were investigated. The pneumatic chamber functioned better when it was placed in a proximal position (third intercostal space) than in a middle or distal position. Using a mock circuit, the performance of the pneumatic chamber as an energy source for a circulatory assist device was evaluated. The pneumatic chamber was able to generate power sufficient to drive a right ventricular assist device as far as stroke work was involved. When the pneumatic chamber was operated with a high afterload, it could even be an energy source for aortic counterpulsation.

Animals↗
PubMedDate not supplied

A compressive type skeletal muscle pump as a biomechanical energy source.

The purpose of this study was to assess the applicability of the conditioned latissimus dorsi muscle as an energy source for circulatory assist devices. The authors developed a pneumatic chamber as a muscle actuator. The pneumatic chamber placed between latissimus dorsi muscle and chest wall was compressed by the burst stimulated muscle and, thereby, converted muscle contractile power into pneumatic pressure. The authors report the performance of the implanted pneumatic chamber at a chronic phase, and the capability of the conditioned muscle in situ as an energy source for circulatory assist devices. Six adult mongrel dogs were used. At the first operation, a pacemaker for muscle conditioning and the pneumatic chamber were implanted. After 12 weeks of muscle conditioning, the performance of the pneumatic chamber with conditioned muscle was evaluated. The pressure generating capability of a chamber buried in fibrous adhesions was reduced to approximately 65% of that of a chamber without adhesions. The stroke volume and stroke work of the assist device driven by the developed pneumatic pressure were measured. The maximum stroke work of the circulatory assist was greater than the stroke work of the right ventricle, but less than that of the left ventricle. In respect to stroke volume, the pneumatic chamber could drive the circulatory assist device against not only a pulmonary range of afterload, but also a systemic range of afterload, when high pre load was available. These results indicate that the compressive skeletal muscle pump with conditioned latissimus dorsi muscle generates acceptable hemodynamic work for right ventricular bypass or aortic counterpulsation. In the long-term, the interface between tissue and actuator is the major obstacle to developing a muscle powered assist device.

Animals↗
PubMedDate not supplied

Spontaneous and agonist-induced contractions and endothelium-dependent relaxation in aortae from SHRSP and WKY rats under various levels of passive force.

1. The influence of the passive force on the contraction and endothelium-dependent relaxation in aortae of normotensive Wistar Kyoto (WKY) rats and stroke-prone spontaneously hypertensive rats (SHRSP) were compared. 2. Force changes of endothelium-intact and -removed preparations were measured isometrically by a force-displacement transducer. Endothelium-dependent relaxation was observed by applying acetylcholine to the preparation precontracted in the presence of 5 x 10(-7) mol/L noradrenaline. 3. The preparations showed spontaneously developed tension (tone) that increased with the increase in the passive force. The effect of passive force was greater in preparations from SHRSP. Contraction initiated by noradrenaline was also increased by passive force up to 30 mN, then showed a tendency to decrease. 4. Endothelium-dependent relaxation was depressed as the passive force was increased. Preparations from SHRSP showed impaired endothelium-dependent relaxation and were influenced by passive force to a lesser degree when compared with preparations from WKY rats. 5. Relaxation by sodium nitroprusside was influenced by passive force to a much lesser extent than that by acetylcholine. 6. Indomethacin potentiated endothelium-dependent relaxation and blocked the effect of passive force in both preparations. 7. The difference in relaxation and the effect of passive force is primarily caused by the difference in the release of endothelium-derived contracting factor, which is thought to be a product of the cyclo-oxygenase pathway of the arachidonic acid cascade.

Acetylcholine↗
PubMedDate not supplied

Complex partial status epilepticus provoked by ingestion of alcohol: a case report.

A 27-year-old man had a 5-year history of a peculiar state characterized by clouded consciousness provoked by ingestion of alcohol. The episode was identified electroclinically as nonconvulsive status epilepticus and was activated by ingestion of alcohol. Single-photon emission computed tomography (SPECT) examination during the nonconvulsive status epilepticus showed increased regional cerebral perfusion in the right frontal region. This finding, along with the EEG expressions, supports a cortical origin of the nonconvulsive status epilepticus and a diagnosis of complex partial status epilepticus (CPSE). To our knowledge, this is the first report of a documented case of CPSE during intoxication provoked by alcohol ingestion and also of a SPECT examination during CPSE.

Adult↗