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Biomedical subjects

M Saitoh

Publications and source records attributed to M Saitoh.

At least 307 records · Page 17Linked to original sources
PubMed1989

Activation of protein kinase C in platelets by epinephrine and A23187: correlation with fibrinogen binding.

Activation of protein kinase C (PKC), as revealed by phosphorylation of a 47 kd protein (p47), occurs in platelets stimulated by some agonists (eg, thrombin or phorbol esters). It is not known if activation of PKC occurs with pairs of agonists, such as epinephrine and A23187, that do not individually phosphorylate p47, nor is it known what role the concentration of cytoplasmic Ca++ ([Ca++]i) plays in these events. We stimulated aequorin-loaded platelets with subaggregating concentrations of epinephrine and A23187, neither of which by itself phosphorylated p47. The combination of agonists resulted in p47 phosphorylation, an increase in platelet-bound fibrinogen, and aggregation, but only if the concentration of each agonist was sufficient to increase [Ca++]i if it was added separately. Subaggregating concentrations of A23187 alone released platelet fibrinogen and increased platelet membrane binding of [3H]-phorbol dibutyrate, but these were not enhanced by epinephrine. Epinephrine and A23187 did not increase production of diacylglycerol. Thus, epinephrine and A23187 together activate PKC by a mechanism that does not require phospholipase C or enhanced binding of PKC to the plasma membrane; PKC activation in turn is correlated with enhanced platelet fibrinogen binding and aggregation. These events require an initial elevation of [Ca++]i above a threshold.

Blood Platelets↗
PubMed1989

Thymic stroma-derived T cell growth factor (TSTGF). IV. Capacity of TSTGF to promote the growth of L3T4- Lyt-2- thymocytes by synergy with phorbol myristate acetate or various IL.

The present study investigates the role of thymic stroma-derived T cell growth factor (TSTGF) in promoting the growth of L3T4- Lyt2- (double-negative) thymocytes. Partially purified TSTGF samples were prepared from the culture supernatant of a newly established thymic stromal cell line, MRL104.8a. The TSTGF alone induced only marginal proliferation of double-negative thymocytes, whereas this factor exerted a potent growth-promoting effect on these cells in combination with PMA. Because such an enhanced proliferation was not inhibited by anti-IL-4 or anti-IL-2R antibody, this was not due to the stimulation of an autocrine mechanism involving the production and utilization of IL-4 or IL-2. In scrutinizing PMA-equivalent physiologic substance(s), IL-1 was revealed to be capable of replacing the role of PMA in the above co-stimulation cultures and including enhanced proliferation of double-negative thymocytes in combination with TSTGF. Although TSTGF plus IL-2 or IL-4 also exhibited an appreciable or moderate synergistic effect on the growth of double-negative thymocytes, its magnitude was weaker compared with that obtained by TSTGF plus IL-1. More important, the strikingly enhanced proliferation was induced in the combinations of TSTGF, IL-1, and IL-2 or IL-4 under conditions in which the proliferation induced by IL-1 plus IL-4 or IL-1 plus IL-2 was marginal or slight. Furthermore, such strongly enhanced proliferation was also observed in the double-negative thymocyte population which was additionally depleted of T3+ cells (namely, the L3T4- Lyt-2- T3- or dull population). These results indicate the crucial role of TSTGF in the proliferation of immature thymocytes by synergy with various cytokines.

Adjuvants, Immunologic↗
PubMed1989

Dermatoses among poultry slaughterhouse workers.

A survey on the incidence of occupational dermatoses among poultry slaughterhouse workers, who, in order to do their work more efficiently, protected their hands only with cotton gloves, revealed that many workers had dermatoses of the hands. Their symptoms included maceration, erosio interdigitalis, paronychia, trichophytia unguium, and eczema, presumably caused by the constant wetness of their hands during work. Candida albicans was detected in the ungual lesions of some patients. A second survey including a skin examination was performed at a plant where preventive measures such as better working gloves and improved sanitary conditions had been implemented because of the high incidence of skin disorders. The results of this survey showed marked improvement in the reduction of the incidence of dermatoses.

Abattoirs↗
PubMed1989

Surgical treatment and radiological consideration of supergiant cerebral aneurysms.

We have collected four cases of supergiant cerebral aneurysm, each greater than 6.0 cm in diameter. Two of these cases were saccular aneurysms of the anterior communicating artery and middle cerebral artery, of which the necks were clipped with resection of the aneurysms. Another patient had a fusiform aneurysm of the middle cerebral artery, which was resected accompanied by a reconstructive procedure of cerebral blood flow. The last patient had a fusiform aneurysm of the internal carotid artery. Following internal carotid artery occlusion surgery with superficial temporal artery-middle cerebral artery anastomosis, the aneurysm completely disappeared radiologically within several months.

Adolescent↗
PubMed1989

Effect of luteinizing hormone-releasing hormone on the mechanical activity of the guinea-pig cardiac muscle.

1. The inotropic effect of physiological concentrations of luteinizing hormone-releasing hormone (LH-RH) in isolated guinea-pig cardiac muscles was studied. 2. LH-RH increased the contractile force elicited by either fast and slow responses in a dose-dependent manner. 3. These effects of LH-RH were affected by phentolamine and diltiazem but not by propranolol and cold condition. 4. This study showed the positive inotropic effect of LH-RH on myocardium through the affection to intracellular Ca, and the difference from the effect of cardiotonic steroids.

Animals↗
PubMed1989

Response of aequorin-loaded platelets to activators of protein kinase C.

The protein kinase C activators phorbol ester 12-myristate 13-acetate (PMA) and 1-oleyl-2-acetylglycerol (DAG) cause platelet aggregation, secretion, and a rise in aequorin-indicated cytoplasmic Ca2+ ([Ca2+]i), but the importance of this action to platelet activation by these agonists has not been established. We found that the previous addition of PMA or DAG either enhanced or inhibited the platelet response if thrombin was subsequently added, depending on the latter's concentration. The effects of PMA or DAG on the response to thrombin were obtained only if the agonists were added in concentrations sufficient to elevate [Ca2+]i themselves. A [Ca2+]i rise also occurred after the second agonist (thrombin), but its magnitude did not necessarily correlate with subsequent aggregation, secretion, or the activation of protein kinase C as reported by the phosphorylation of a 47-kDa protein (p47). The protein kinase C inhibitor sphingosine inhibited aggregation and p47 phosphorylation caused by PMA or DAG alone or with thrombin, but the [Ca2+]i rise in response to the first agonist was not affected. PMA-induced aggregation and p47 phosphorylation were inhibited by quin2, which also inhibited protein kinase C activity in a cell-free system. We conclude that a rise in aequorin-indicated [Ca2+]i is necessary for PMA or DAG to activate platelets or to alter the subsequent platelet response to thrombin; this [Ca2+]i rise may be a prerequisite for activation of protein kinase C.

Aequorin↗
PubMed1989

Determination of left to right shunt by thermodilution in patients with ventricular septal defect.

A modified thermodilution technique was used to determine the quantity of shunt in patients suffering from congenital heart disease with a left to right shunt. In our modification, the thermistor was placed within the pulmonary artery and an indicator was injected into both sides of the heart. In a series of 33 cardiac catheterizations in children (1-17 years) with ventricular septal defect (VSD), pulmonary blood flow (Qp), systemic blood flow (Qs) and the ratio of Qp to Qs (Qp/Qs) were determined by this and ordinary oximetry (Fick) methods. Correlation coefficients between indexes obtained by these methods were 0.54 (Qp), 0.78 (Qs), and 0.75 (Qp/Qs). The estimates of Qp and Qp/Qs obtained by thermodilution were smaller than those obtained by the Fick method. This modification of thermodilution is simple, rapid, and useful in clinical practice.

Adult↗
PubMed1989

[Partial liver transplantation techniques for future clinical application].

Using grafts from brain-dead donors for liver transplantation is a very controversial subject in Japan and those candidates for transplantation who have received livers outside of Japan have been harshly criticized. Under these circumstances, a partial liver transplantation is an attractive method in terms of preserving the donor's life, freshness of the graft and easier donor availability. In other words, for adults with non-cancerous incurable liver disease the donor's left lobe can be transplanted after the recipient has had a left lobectomy, and for children with biliary atresia the whole liver and vena cava can be replaced with a parent's left lobe and iliac vein. Our report concerns the procedures of orthotopic partial liver transplantation for canines and humans.

Animals↗
PubMed1989

Comparison of lung virus titers in susceptible and resistant inbred mouse strains against Sendai virus infection.

Susceptibility of inbred mouse strains to Sendai virus (Mol strain) infection was studied. Although some mouse strains showed age differences in susceptibility between 3-to 4-week-old and 7-to 8-week-old mice, such age differences in susceptibility were not observed in susceptible DBA/2N and resistant BALB/cA mice. In 7-to 8-week-old mice, remarkable strain differences were observed in mortality and intensity of the lung lesions, but not in lung virus titers and serum antibody, between resistant BALB/cA and susceptible DBA/2N mice.

Age Factors↗
PubMed1989

[Studies on the retentive force of clasps. 1. An effect of the material and technician].

Wire clasps and cast clasps are the most common retainers for removable partial dentures. The purpose of this study was to investigate the differences in the material and the variation among individual technicians in the retentive force of both clasps. The clasps were made in accord with the clinical method for experimental metallic model of the left mandibular second premolar and the retentive force of each clasp was measured by a pull-out test. The results were as follows: 1. Both types of clasp showed a large variation in the retentive force among the technicians, but no particular tendency was observed in the differences between wire and cast clasps. 2. There was no significant difference between the two types of clasp in the retentive force. 3. Due to the differences in individual technical skills, it seems to be difficult to make wire clasps with a standardized retentive force.

Denture Design↗
PubMed1989

[Study of a particle counting method for index of masticatory efficiency].

The present report discusses our new simplified measuring method of masticatory efficiency by counting particles in the matter of making test materials and the standard equation for subjects with normal dentition. 1. Two kinds of hydrocolloid impression materials, reversible and irreversible, were used as the test materials. 2. For evaluating the shape of test materials, 12 subjects with normal dentition were tested and for calculating the standard equation, 108 subjects with normal dentition were tested. 3. Each subject was investigated by the simplified method of counting particles through a sieve system. The number of remaining particles on the mesh was calculated as a masticatory performance. 4. As indicated in a previous report by Dr. Ozawa about cubical test materials, columnar test materials are easier to make than the others and these were avairable for the present particle counting method for investigating masticatory efficiency. 5. We obtained the standard equation for both kinds of test material using 108 subjects with normal dentition. To simplify the measuring method, we selected the standard equation of a 5-mesh sieve with 10 strokes chewing for the index of masticatory efficiency. The standard equation of a 5-mesh sieve for both test materials are as follows; 1) Reversible hydrocolloid test material: Y = -1.605X+29.058 2) Irreversible hydrocolloid test material: Y = -1.116X+23.868 6. 5, 10-mesh sieve with 10 strokes chewing showed the smallest variation in the individual coefficient of variation with both kinds of test material.

Colloids↗
PubMed1989

[Water sorption, solubility, MeOH sorption and THF sorption of visible light cured resin--on resin using cyclophosphazene monomers and commercial monomers].

Studies were done to decrease both the water sorption and solubility of visible light cured resin. As monomer, three kinds of cyclophosphazene monomers and three kinds of commercial monomers were prepared to the visible light cured unfilled resins. When these set products were immersed in water, MeOH and THF, water sorption and solubility in water, MeOH sorption and solubility in MeOH, THF sorption, and mechanical properties were examined. Water sorption was increased by degrees for all the monomers. In the cases of 4 PN-(EMA)8, 4 PN-(TF)1-(EMA)7, 4 PN-(TF)2-(EMA)6, Tri-EDMA, BMPEPP and Bis-GMA + Tri-EDMA, the value of solubility in water after 30 days, was 0.16, 0.20, 0.51, 0.65, 0.17 and 0.81% respectively. MeOH sorption showed a tendency to increase, except for Bis-GMA + Tri-EDMA and 4 PN-(TF)2-(EMA)6. Solubility in MeOH after 30 days, for cyclophosphazene monomers and commercial monomers, was 0.09-0.36% and 1.36-5.40%. THF sorption after 30 days, for cyclophosphazene monomers, was small in comparison with that of commercial monomers. Compressive strength was 230-275 MPa in all cases. But, transverse strength, for all the cyclophosphazene monomers, was 45 MPa or below. In the cases of commercial monomers, the value of transverse strength was 55-90 MPa.

Acrylic Resins↗
PubMed1989

[The use of an omental pedicle flap in the closure of a wide bronchial fistula after pneumonectomy: a case report].

A 52-years-old man with pulmonary hypofunction had a squamous cell lung carcinoma and underwent the right upper lobectomy. Bronchial fistula with lung abscess developed on the 6th post-operative day. So, the right middle and lower lobectomy (completion pneumonectomy) were done. But, bronchial fistula again appeared at the time of weaning from respirator. It increased in size to about 4.0 x 2.0 cm. Then, transposition of an omental pedicle flap for closure on a wide bronchial fistula, and muscular plombage and thoracoplasty for semifilling up a secondary empyema cavity were performed. On bronchoscopy performed 14 days after operation, the fistula was completely closed, and the transposed omentum did not project into the trachea. We accomplished our first aim to close the wide bronchial fistula with omentum. However, he died 59 days after the 3rd operation because we failed to control infection of the remaining empyema cavity of about 100 ml. The management of an empyema cavity remains to be a difficult therapeutic problem.

Bronchial Fistula↗
PubMed1989

[Extracorporeal adriamycin-removal following hepatic artery infusion: use of direct hemoperfusion combined with veno-venous bypass].

Systemic toxicity of adriamycin (ADR) has limited its high dosage application in hepatic artery infusion. We developed a new extracorporeal device combining direct hemoperfusion (DHP) and veno-venous bypass to eliminate ADR following hepatic artery infusion. Mongrel dogs were divided into three group, I: controls without DHP (n = 3), II: DHP under single venous bypass from IVC to left external jugular vein (n = 3) and III: DHP under hepatic venous isolation using veno-venous bypass (n = 5). Blood specimens were obtained to determine plasma drug levels until 60 min after ADR injection (3 mg/kg body weight, 1 min). Blood flow through DHP, which was averaged 200 ml/min in both groups II and III, was monitored with ultrasonic flowmeter. In groups I and II, peripheral ADR levels rapidly increased, reaching the peak values of 5.61 +/- 2.42 and 1.17 +/- 0.31 micrograms/ml respectively at 1 min after injection. The peak level in group III was markedly reduced, the value being 0.42 +/- 0.17 microgram/ml, which was 7.5% of the peak value of group I. The removal rates in groups II and III were 10.9 and 27.5% respectively. In conclusion, DHP under hepatic venous isolation can be an useful method to reduce systemic distribution of ADR during hepatic artery infusion.

Animals↗