Search PubMed⌕ Search

Biomedical subjects

M Sakaki

Publications and source records attributed to M Sakaki.

At least 37 records · Page 2Linked to original sources
PubMed1993

Reduced gastric mucosal blood flow in patients with portal-hypertensive gastropathy.

Although congestive gastric mucosal circulation has been suggested in patients with portal-hypertensive gastropathy, whether it is due to "active" (overflow) or "passive" (stasis) congestion is not known. To answer this question, we assessed regional gastric mucosal blood flow with laser Doppler flowmetry in 57 patients with portal hypertension and 30 controls. Twelve patients had portal-hypertensive gastropathy of the antrum: in eight it was mild and in four it was severe. Portal-hypertensive gastropathy of the corpus was seen in 32 patients: it was mild in 24 and severe in 8. Thus prevalence of portal-hypertensive gastropathy was higher in the corpus than in the antrum (p < 0.01). In the antrum, gastric mucosal blood flow was significantly lower (p < 0.05) in patients with severe portal-hypertensive gastropathy (0.54 +/- 0.27 V) than in controls (1.12 +/- 0.44 V), whereas the values in patients without portal-hypertensive gastropathy (0.90 +/- 0.35 V) and with mild portal-hypertensive gastropathy (0.91 +/- 0.31 V) were not significantly different from the values in controls (p < 0.05 on one-way analysis of variance). In the corpus, gastric mucosal blood flow was significantly lower in patients with mild (0.75 +/- 0.25 V) or severe portal-hypertensive gastropathy (0.42 +/- 0.22 V) than in controls (1.16 +/- 0.37 V) (p < 0.01 and p < 0.01, respectively) whereas the value in patients without portal-hypertensive gastropathy (0.99 +/- 0.37 V) was not significantly different from values in controls (p < 0.01 on one-way analysis of variance).(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1992

Nicardipine infusion improved hepatic function but failed to reduce hepatic venous pressure gradient in patients with cirrhosis.

We investigated the effects of nicardipine on systemic and splanchnic hemodynamics and on liver function in 16 patients with cirrhosis and portal hypertension. Patients received a continuous infusion of 0.3 mg/min of nicardipine (n = 10) and a control infusion (n = 6). No significant changes were observed after a control infusion. In contrast, systemic vasodilatation, evidenced by a significant fall in mean arterial pressure (-14%, p less than 0.01) and systemic vascular resistance (-30%, p less than 0.01), increased heart rate (+8%, p less than 0.01) and cardiac output (+21%, p less than 0.01), and increased hepatic blood flow (+43%, p less than 0.01) were observed at 60 min after a continuous infusion of nicardipine. Although nicardipine improved hepatic function (intrinsic clearance from 0.29 +/- 0.13 to 0.33 +/- 0.15 L/min, p less than 0.05), portal pressure evaluated by hepatic venous pressure gradient was not reduced significantly (from 16.3 +/- 4.9 to 15.1 +/- 5.7 mm Hg; NS). We conclude that a continuous infusion of nicardipine improves liver function but has no beneficial effect on portal pressure in patients with cirrhosis.

Adult↗
PubMed1992

Portohepatic pressures, hepatic function, and blood gases in the combination of nitroglycerin and vasopressin: search for additive effects in cirrhotic portal hypertension.

We studied the effects of the combination of nitroglycerin and vasopressin on portohepatic hemodynamics, hepatic function, and blood gases in nine patients with cirrhosis and portal hypertension. Vasopressin infusion at a dose of 0.4 U/min caused a significant fall in portal pressure, which is evaluated by portal venous pressure gradient (-34%, p less than 0.01), associated with a decrease in hepatic perfusion (-33%, p less than 0.01) and intrinsic clearance (-20%, p less than 0.01) after 30 min. The arterial oxygenation, however, was not modified (paO2; from 73 +/- 8 to 72 +/- 7 mm Hg, NS). Nitroglycerin infusion at a dose of 100 micrograms/min was then administered for 20 min. The addition of nitroglycerin produced a further reduction in free portal venous pressure (-12%, p less than 0.01), but this was not associated with a significant improvement in both hepatic perfusion (+16%, NS) and intrinsic clearance (-7%, NS). In addition, there was a significant fall in arterial oxygenation (paO2; from 72 +/- 7 to 59 +/- 5 mm Hg, p less than 0.01). We conclude that the addition of nitroglycerin to vasopressin has a beneficial effect on free portal venous pressure, but does not have hepatic benefit. Moreover, sufficient care must be taken, when treating portal hypertension with this combination, to avoid arterial hypoxemia.

Aged↗
PubMed1991

[Serotypes and antibiotic sensitivity of hemolytic streptococci isolated from clinical specimens in Hiroshima Prefecture, 1987-1989].

The grouping, the typing and the drug-sensibility of hemolytic streptococci isolated from the clinical specimens taken from 4 medical centers in Hiroshima Prefecture have been examined and reviewed during the past 3 years 1987-1989. The results were summarized in this report. 1. Of 1572 strains of hemolytic streptococci, 844 strains (53.7%) were group A; 539 strains (34.3%), group B; 14 strains (0.9%), group C; 82 strains (5.2%), group G; and 93 strains (5.9%), the others. We found that group A and group B were predominant, and the incidence rate of group B was higher than it used to be. 2. The prevalent types were T-4 (37.9%), T-1 (13.6%), T-12 (12.0%), and T-28 (10.7%) in group A, while Ia (26.2%), M9 (provisional type 18.4%), and III (14.5%) in group B. 3. As far as the detection data of each month is concluded, during the summer season we could hardly detect group A which peak of occurrence during the winter season. These findings were really consistent with the occurrence pattern of those patients who suffered from streptococcal infectious disease. But this occurrence pattern couldn't be found in group B. 4. In our study, the positive frequency was throat swab greater than urine greater than sputum greater than vaginal swab greater than pus greater than ear secretion in order. Group A was mainly isolated from throat swab, while group B, from several specimens including urine. 5. We found that there was a high drug-sensibility to the beta-lactam drugs in all strains except for 3 strains of group B which were resistant to CEX.(ABSTRACT TRUNCATED AT 250 WORDS)

Anti-Bacterial Agents↗
PubMedDate not supplied

Gastric mucosal blood flow after smoking in healthy human beings assessed by laser Doppler flowmetry.

We measured regional gastric mucosal blood flow by laser Doppler flowmetry before and after control (n = 8) or cigarette smoking (n = 8) in healthy human beings. The control group showed no change in both antrum (from 1.15 +/- 0.32 to 1.20 +/- 0.39 V, NS) and corpus gastric mucosal blood flow (from 1.15 +/- 0.32 to 1.12 +/- 0.28 V, NS). In contrast, cigarette smoking caused a significant reduction in gastric mucosal blood flow in the antrum (from 1.08 +/- 0.31 to 0.71 +/- 0.22 V, p < 0.01) and in the corpus (from 0.99 +/- 0.26 to 0.66 +/- 0.24 V, p < 0.01). The magnitude of reduction in gastric mucosal blood flow was similar between the antrum and the corpus (-34% +/- 11% versus -33% +/- 15%, NS). We conclude that cigarette smoking induces a significant reduction in gastric mucosal blood flow and that no heterogeneous response occurs in regional gastric mucosa. In addition, the laser Doppler flowmeter appears to be a sensitive method to assess rapid change in gastric mucosal blood flow in human beings.

Adult↗
PubMedDate not supplied

McCormack's endoscopic signs for diagnosing portal hypertension: comparison with gastroesophageal varices.

To assess the significance of McCormack's gastric mucosal signs for diagnosing portal hypertension, 100 controls and 100 patients with cirrhosis and portal hypertension underwent endoscopy. Each endoscopic recording was reviewed by multiple blinded observers to reduce bias. Individual signs more frequently observed in patients with cirrhosis and portal hypertension than in controls were fine pink speckling (20% versus 8%, p < 0.05), the snakeskin pattern (30% versus 5%, p < 0.01), and cherry-red spots (15% versus 3%, p < 0.01). In contrast, the prevalence of superficial reddening was similar in the two groups (7% versus 13%, NS). Overall, these gastric mucosal signs also appeared more commonly in patients with portal hypertension than in controls (54% versus 27%, p < 0.01); the sensitivity, specificity, and accuracy of McCormack's signs (overall assessment) for diagnosing portal hypertension were 54%, 73%, and 64%, respectively. Corresponding figures for modified McCormack's signs (exclusion of superficial reddening) were 50%, 85%, and 68%. However, these figures were still lower than those for gastroesophageal varices (72%, 100%, and 86%). We conclude that (1) superficial reddening is not a specific finding in patients with portal hypertension, and (2) gastric mucosal findings are of low sensitivity and specificity for diagnosing portal hypertension compared with gastroesophageal varices.

Esophageal and Gastric Varices↗
PubMedDate not supplied

A bioartificial ventricle used as a totally implantable circulatory assist device.

The authors designed a totally implantable circulatory assist device consisting of a bioartificial ventricle composed of a skeletal muscle ventricle lined with a bioartificial endocardium. The bioartificial endocardium consists of a structural matrix made of a polyurethane porous membrane, fragmented blood vessels, and collagen gel. The authors prepared the polyurethane porous membrane by solvent cocasting with salt powder. They used collagen gel with fragmented goat carotid vein to perform in vitro construction of the bioartificial endocardium. For in vivo construction of the bioartificial endocardium, the authors used a modified version of the tissue fragment method for vascular prostheses. The authors prepared suspensions of tissue fragments using collagen gel with fragmented goat carotid artery. They used a highly porous fabric vascular prosthesis as a structural matrix; tissue fragments were entrapped on the outer surface of the prosthesis, and the prosthesis then was implanted into the carotid artery of four adult goats. In specimens 1 and 3 months postimplantation, cells from the fragmented tissue regenerated an endothelium-like monolayer sheet on the inner surface of the prostheses. Output of a prototype bioartificial ventricle reached 660 ml/min at an afterload of 60 mmHg and a preload of 20 mmHg. Based on these data, the authors conclude that the bioartificial ventricle is promising as an implantable device with excellent antithrombogenicity.

Animals↗
PubMedDate not supplied

Pulmonary function in a non-pulsatile pulmonary circulation.

The authors suggested that a mammal immediately accommodates well to nonpulsatile flow in the systemic circulation. In the current study, nonpulsatile pulmonary blood flow using a centrifugal pump was established in chronic models to analyze its influence on the pulmonary circulation. A pulsatile right ventricular assist device (RVAD) was implanted to draw blood from both the right atrium and ventricle and send blood to the pulmonary artery in six goats. After 2 weeks, the pulsatile pump was quickly replaced with a centrifugal pump without anesthesia, and a 100% non-pulsatile pulmonary blood flow was obtained. Cardiac output was kept at 80-120 ml/kg/min during the experiments. No changes were observed in hemodynamic parameters, including pulmonary arterial pressure, pulmonary vascular resistance index, and blood gas data, after the immediate depulsation of the pulmonary blood flow. There was also no significant change in the ventral to dorsal tissue blood flow ratio of the lower lobe of the right lung, which was calculated by a colored microsphere method, between pulsatile and non-pulsatile pulmonary blood perfusion. These results suggest that pulmonary function, including blood flow distribution, is not affected by non-pulsatile pulmonary circulation for periods up to 14 days.

Animals↗
PubMedDate not supplied

Permeation of silicone oil through a diaphragm in an electrohydraulic ventricular assist system.

This study was designed to investigate the permeation of silicone oil through a pump diaphragm made of Pellethane in the authors' electrohydraulic ventricular assist system (EHVAS) and to evaluate influences on organ function. The permeability of the diaphragm to silicone oil was investigated by in vitro experiments. Influences on organ function were evaluated in five goats with an EHVAS by monitoring serum silicon levels (SSi), blood chemical parameters, and histologic findings. Elevation of silicone oil levels in Pellethane sheets immersed in silicone oil demonstrated that the Pellethane diaphragm was, in fact, permeable to silicone oil. The permeation rate of silicone oil was calculated to be 1.75 ml/year in the authors' EHVAS from the data of a diffusion apparatus test. Serum silicon levels did not increase during the EHVAS pumping, and renal and hepatic function were not affected. No abnormality or deposit suggestive of silicone oil was observed. However, the problem of permeation of silicone oil through the pump diaphragm must be solved to allow for a circulatory assist device for long-term use.

Animals↗
PubMedDate not supplied

Influence of an impeller centrifugal pump on blood components in chronic animal experiments.

A chronic animal experiment was designed to examine the changes in blood components induced by the use of a centrifugal pump (CP). In the pump, an impeller spins in a blood chamber by magnetic coupling with a rotating magnet outside the blood chamber. A pulsatile ventricular assist device was implanted between the left atrium and the descending aorta in four goats weighing from 63 to 75 kg; the CP was installed to replace the assist device, without surgery and anesthesia, more than 2 weeks later when the influences of implantation surgery were diminished. Antithrombotic therapy was performed with oral administration of an antiplatelet agent, cilostazol, a cyclic adenosine monophosphate phosphodiesterase at a dose of 30 mg/kg/day. No significant differences were observed in any of the following parameters: 1) hematocrit, 2) plasma free hemoglobin, 3) lactic acid dehydrogenase, 4) adenosine diphosphate, 5) platelet count, 6) fibrinogen, and 7) antithrombin III, between the data before and after the use of the CP, nor were deformation or pseudopods of platelets seen. The CP developed in the authors' institute and evaluated in this study did not damage blood components, and it proved to be a promising device for long-term use.

Adenosine Diphosphate↗
PubMedDate not supplied

An abdominally placed, implantable left ventricular assist system for long-term use.

An implantable left ventricular assist system was developed for long-term use. The system includes an implantable blood pump, a portable control drive unit (CDU), and a monitoring system. The blood pump was designed to be positioned in the left abdominal wall and was made of segmented polyether polyurethane. A percutaneous drive line connected it to the external CDU. The CDU included a continuous pump performance monitoring system that measured electrical impedance between the two metal connectors of a blood pump. In animal experiments using six adult goats, the pump was installed between the left ventricular apex and the descending aorta, and it was placed in the abdominal wall. No antithrombogenic agents were administered during the course of the experiment. This LVAS was easy to use and provided stable hemodynamic conditions for > 8 weeks. Pump output (Op), estimated by impedance, was linearly related to Op measured with an electromagnetic flowmeter. Pump performance was effectively estimated, and the fill-empty drive was well controlled by impedance. There were no significant abnormal hematologic or blood chemistry values, no signs of infection around the pump pocket (except in one animal), and no obvious thromboembolic symptoms. Maximum flow was 6.7 L/min with use of a prototype portable CDU (dimensions, 500 x 168 x 435 mm; weight, 16 kg). In conclusion, this LVAS is promising for long-term clinical use.

Abdomen↗
PubMedDate not supplied

Lack of hepatic benefit by oxygen inhalation during vasopressin infusion in patients with cirrhosis.

Vasopressin has been found to impair hepatic function in patients with cirrhosis. The aim of this study was to investigate whether oxygen inhalation could improve hepatic function during vasopressin infusion. Vasopressin (0.3 iu/min) was infused into eight patients with cirrhosis for 50 min. During the first 30 min they were ventilated by room air and for the following 20 min by oxygen (approximate 50% of FiO2). The extra oxygen inhalation caused a typical increase in arterial (+7%, P less than 0.01), portal venous (+8%, P less than 0.05), and hepatic venous (+9%, P less than 0.01) oxygen content. No effect was noted in arterio-hepatic venous and portal venous-hepatic venous oxygen content difference in comparison with the values after vasopressin alone. The hepatic perfusion remained unchanged. These results suggest that the extra oxygen did not increase hepatic oxygen uptake. Similarly, intrinsic clearance of indocyanine green did not improve. It is concluded that oxygen supplement in this setting has no hepatic benefit in patients with cirrhosis.

Adult↗
PubMedDate not supplied

Chronic evaluation of a compact nonseal magnet pump as a nonpulsatile pump for long-term use.

Use of a nonpulsatile pump is one of the most interesting approaches in the development of artificial hearts. A centrifugal pump without a seal around the rotating part was evaluated in five goats. The size of the pump is 8.4 cm x phi 7.0 cm, including an electric motor. A polypropylene impeller with four fins on the top of a column in which a magnetic ring is embedded spins by coupling with a rotating magnet outside the housing. In the goats, the pump was placed paracorporeally to provide total left heart bypass at a flow rate of 4.6-7.6 L/min, and activated clotting time was controlled at 200-300 sec by continuous heparin infusion. Although the first three goats died within 3 days due to bleeding, embolism, and a jammed impeller, respectively, a pump could be driven for 14 days in the fourth goat, and another pump with a rotational control feedback system ran for 32 days in the fifth goat. Plasma free hemoglobin levels were 13.8 +/- 4.3 mg/dl and 9.5 +/- 2.5 mg/dl, and platelet counts were 53.8 +/- 24.7 x 10(4)/mm3 and 62.0 +/- 22.0 x 10(4)/mm3 after 12 hours and 7 days pumping, respectively. No thrombus was observed in the blood chamber in the last two cases. In conclusion, this pump has possibilities as a nonpulsatile pump for long-term use.

Animals↗
PubMedDate not supplied

Easy access for a left ventricular assist system without thoracotomy.

In a previous article, a left ventricular assist system (LVAS) with a percutaneous transseptal cannulation technique for easy application was described. This system was safe and efficient (maximum output greater than 3 L/min) and fitted between the intraaortic balloon pumping and LVAS with thoracotomy. But technical skill for placement was slightly complicated. The cannulation system has been improved. In the new system, the inlet cannula is initially used as a sheath introducer and is quickly inserted into the left atrium after transseptal puncture. The new inlet cannula is made of polyvinyl chloride (TM100, Toyobo, Co., Ltd., Osaka, Japan), which has excellent antithrombogenicity and low friction using a polyester plasticizer. The distal part is designed to be flexible with a spiral wire for easy manipulation. A sealing hub was installed to prevent bleeding at the proximal The simplicity and safety of the new system were examined in chronic animal experiments. The inlet cannula was placed into the left atrium within a few seconds after transseptal puncture. During 20 days of activation, there were no episodes of systemic or pulmonary embolism, although no anticoagulant was used. Under fluoroscopy, there was no thrombus formation around the cannula at removal. On the 14th day after removal, the puncture site of the septum had healed. This system is ready for clinical use and shows promise of satisfactory safety and manageability.

Animals↗
PubMedDate not supplied

An integrated artificial heart-lung device.

An integrated artificial heart-lung device (IAHLD) is being developed as a novel system for simultaneous long-term support of heart and lung. The IAHLD consists of an artificial lung component (LC) and two blood pumps. The LC is made with a special composite hollow fiber membrane that prevents serum leakage. The fibers are arranged as piled-up lattices and potted in a cylindrical housing made of polyurethane. The blood pump with a single port is of a pneumatic pusher-plate type, and a Björk-Shiley valve is mounted in the port. The LC is sandwiched between the inlet and outlet pumps, and all components are integrated. This special structure provides high gas exchange efficiency, prevention of flow channeling and stagnation, and reduction of blood contacting surfaces. The prototype IAHLD had exchange rates of up to 170 ml/min of O2 and CO2 and up to 5.5 L/min of pump output. A flow visualization analysis with cineroentgenography revealed that the flow distribution within the IAHLD was uniform, without any stasis. It was concluded that the IAHLD is a promising system for long-term heart and lung support, and can be used without systemic heparinization given thromboresistant surface treatment as the next step of development.

Animals↗