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Biomedical subjects

Y Kokubo

Publications and source records attributed to Y Kokubo.

At least 55 records · Page 3Linked to original sources
PubMed1996

Inhibitory effects of phenolic compounds on development of naturally occurring preneoplastic hepatocytic foci in long-term feeding studies using male F344 rats.

Five phenolic compounds, namely caffeic acid, sesamol, hydroquinone, catechol, and 4-methoxyphenol, were fed to groups of 30 male F344 rats at dietary levels of 2, 2, 0.3, 0.8, and 2%, respectively, for 2 years. Retardation of body weight and elevated relative liver weights were noted for all groups. Formalin-fixed and paraffin-embedded liver tissues from rats killed terminally were cut and stained for glutathione S-transferase placental form (GST-P) and tumor growth factor alpha (TGF alpha) immunohistochemically. Numbers and areas of GST-P-positive (GST-P+) foci per unit area of liver section were measured, and the respective treated/control proportional values were calculated to be 58 and 57% for caffeic acid. 58 and 54% for sesamol, 71 and 71% for hydroquinone. 58 and 133% for catechol, and 49 and 39% for 4-methoxyphenol. These data were comparable with results obtained with medium-term liver bioassays (Ito test). However, no intergroup differences were detected with regard to quantitative findings for TGF alpha foci, which were relatively rare. Long-term inhibitory effects of phenolic compounds on liver carcinogenesis, predicted from the Ito test, were thus confirmed in the present feeding studies using quantitative analysis of immunohistochemically demonstrable GST-P+ foci as end point marker lesions.

Animals↗
PubMed1996

Apoptosis of neutrophils and their elimination by Kupffer cells in rat liver.

The fate of neutrophils in the peripheral circulation is poorly understood. In this study, the role of Kupffer cells in eliminating aged and apoptotic neutrophils was investigated. Liver, spleen, lung, and blood samples from Wistar rats were examined by light and electron microscopy, the terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate-biotin nick end labeling (TUNEL) method, and immunohistochemistry after the intravenous injection of OK-432, a streptococcal preparation. Neutrophils were trapped predominantly in the periportal and midzonal regions of hepatic lobules and were in contact with endothelial cells and Kupffer cells, or were surrounded by Kupffer cells. The trapping of neutrophils peaked after 6 hours. Apoptotic neutrophils, with or without buds, were found in the lumen of hepatic sinusoids as early as 6 hours, reached maximal levels after 12 hours, and represented greater than 60% of the total number of neutrophils in the liver. The presence of apoptotic neutrophils was correlated with the degree of neutrophil phagocytosis. Double-staining showed that TUNEL-positive neutrophils were phagocytosed or encircled by ED1- or ED2-positive Kupffer cells. In contrast, apoptosis and phagocytosis of neutrophils were rare in the spleen, lung, and peripheral blood. These results suggested that the appearance of apoptotic neutrophils in the hepatic sinusoids and their rapid clearance by Kupffer cells occurs after the invasion of bacteria (i.e., bacteremia or bacteriotoxemia) or the release of inflammatory mediators into the blood stream. These findings have important implications for the regulation of neutrophil homeostasis, the limitation of inflammation and tissue injury, and provide insight into the physiological removal of circulating, senescent neutrophils.

Animals↗
PubMed1996

[A case of agammaglobulinemia with chronic enteroviral meningomyelitis].

We report a 30-year-old man with agammaglobulinemia and chronic aseptic meningomyelitis. The patient was diagnosed as having X-linked recessive agammaglobulinemia at 4 years of age and gammaglobulin supplementation was started. He had TIA-like episodes several times since 25 years of age. He developed difficulty in micturition and impotence at 29 years of age. Neurological examination revealed bilateral deafness, contracture of knee joints, slight weakness and areflexia in the lower extremities, Babinski sign and dysuria. There was sensory disturbance in the lower extremity on the left. There was not consciousness disturbance or meningeal irritation sign. The cerebrospinal fluid findings included pleocytosis and increase in protein. Enterovirus RNA was detected in the cerebrospinal fluid by the modified polymerase chain reaction (PCR) method. MRI of lower spinal cord showed syrinx formation in the lumbosacral cord and CT of the brain showed bilateral temporal lobe atrophy and temporoparietal subdural fluid collection on the left. 123I-IMP SPECT showed decrease in the cerebral blood flow in the whole brain. EEG showed diffuse slow activity, suggesting the subclinical encephalopathy. Chronic enteroviral meningoencephalitis with agammaglobulinemia (CEMA) is one of the complications of agammaglobulinemia. However, myelitis without apparent encephalopathy is very rare. To our knowledge, there have been no reports of spinal sylinx formation in CEMA.

Adult↗
PubMed1996

[A case report of exercise-induced anaphylaxis].

We report a case of 44-year-old Japanese man who presented with exercise-induced anaphylaxis. He was admitted to our hospital with chief complaints of repeated episodes of urticaria and nausea induced by exercise. He had allergy to the radiologic contrast iodine material, but no history of atopic dermatitis. Physical and neurological examinations were unremarkable. Treadmill test induced urticaria and nausea in 10 minutes after starting the exercise and the test was discontinued. The systolic blood pressure finally fell down to 51mmHg about 17 minutes after ceasing the exercise, and it returned to normal value with hydrocortisone and noradrenalin injection. Treadmill test increased the serum histamine level, but did not increase serotonin nor IgE levels. Administration of antihistamines and avoidance of hard exercise has protected him from a new attack. We have to pay attention to exercise-induced anaphylaxis as one of the important causes of syncope.

Adult↗
PubMed1995

Rapidly progressing quadriparesis secondary to cervical pyogenic spondylitis in a patient with Klippel-Feil syndrome.

We report a case in which the patient's quadriparesis progressed rapidly secondary to pyogenic spondylitis with an epidural abscess of the cervical spine. The patient had type II Klippel-Feil congenital fusion at C3-C4 that may have obscured clinical symptoms, resulting in a slight delay in the diagnosis of spondylitis. Magnetic resonance imaging (MRI) facilitated the determination of the precise location of the epidural abscess, and anterior debridement of the involved vertebrae followed by iliac strut bone grafting led successfully to the patient's full neurological recovery. The case presented is instructive in illustrating the importance of an early diagnosis followed by the appropriate treatment.

Abscess↗
PubMed1994

Adsorption of anaphylatoxins and platelet-specific proteins by filtration of platelet concentrates with a polyester leukocyte reduction filter.

Anaphylatoxins generated during storage of platelet concentrates (PCs) may potentially have side effects on platelet transfusion. We evaluated the anaphylatoxin-scavenging abilities of white blood cell reduction filters. Among the commercially available filters for PCs, one made with polyester fiber (PL50) dramatically adsorbed C3a and C4a anaphylatoxins to the respective mean level of 1,721-208 ng/ml and 1,240-141 ng/ml in 3-day-old PCs. C3a and C4a were measured as the native and des Arg form of each complement by radioimmunoassay. C3a and C4a anaphylatoxins in the supernatant plasma fraction from 3-day-old PC again decreased from 1,136 to 114 ng/ml and from 1,086 to 65 ng/ml, respectively. The filter also adsorbed 85% of platelet factor 4 (PF4) and 31% of beta-thromboglobulin (beta-TG), which had been released from platelets into the plasma during storage. The plasma levels of adhesive proteins such as fibronectin, fibrinogen, and von Willebrand factor, and plasma lactate dehydrogenase activity did not decrease after filtration. Another polyester filter (PL5A), on the other hand, significantly increased C3a and C4a levels with filtration. In addition, there was no PF4 adsorption ability during the filtration. The filters for red cells (RC50, BPF4, and R500A) had no anaphylatoxin adsorption capabilities. The observed specific adsorption of anaphylatoxins might be attributed to the electrostatic force between the positively charged anaphylatoxins with high pI and the possibly negatively charged filter membranes. Since PF4 and beta-TG have positively charged moieties in the C-terminal position, the same adsorption mechanism might operate.(ABSTRACT TRUNCATED AT 250 WORDS)

Adsorption↗
PubMed1993

Filtration through a polyester white cell-reduction filter of plasma-poor platelet concentrates prepared with an acetate-containing additive solution.

It is of practical importance to known whether the adsorption of platelets and contaminating white cells (WBCs) by the WBC-reduction filter is altered when platelet concentrates (PCs) are prepared in a plasma-poor condition with an acetate-containing additive solution (Seto sol). Plasma-poor PCs with 11-percent residual plasma were prepared from apheresis platelet-rich plasma by using a sterile docking device with steam-sterilized Seto sol. Seto sol contains 115 mM (115 mmol/L) NaCl, 4 mM (4 mmol/L) KCl, 3 mM (3 mmol/L) MgCl2, 10 mM (10 mmol/L) Na3PO4, 15 mM (15 mmol/L) acetate, 3 mM (3 mmol/L) Na3 citrate, and 10 mM (10 mmol/L) glucose (pH 7.1). The solution was steam-sterilized under nitrogen gas. On Days 1 and 5, pooled Seto sol PCs (2.4 x 10(11) platelets) were filtered with a polyester filter at a flow rate of 10 mL per minute. The WBC-removal rate was over 99.9 percent with a platelet recovery of 88 percent following Day 1 filtration. These values were very similar to those of plasma PCs, and 84-percent recovery was achieved following Day 5 filtration. However, when 1 unit of Seto sol PCs with half the number of platelets was filtered with the polyester filter, platelet recovery was about 16 to 17 percent less than that of plasma PCs. Platelet quality was maintained if pooled Seto sol PCs were filtered on Day 1 and stored for over 4 days. Filtration did not alter platelet function in 1-day-old or 5-day-old Seto sol PCs.(ABSTRACT TRUNCATED AT 250 WORDS)

Adsorption↗
PubMed1989

Determination of acetaldehyde in human blood by high-performance liquid chromatography using fluorometry.

A method was developed for the measurement of acetaldehyde in human blood by high-performance liquid chromatography (HPLC). The method was based on a pre-column reaction; a fluorescent substance was formed by a coupling reaction between 2 mol of cyclohexan-1,3-dione and 1 mol of acetaldehyde with ammonium acetate. The coupling compound was analyzed by HPLC and the concentration of acetaldehyde was obtained from the calibration curve drawn from the results using standard solutions. The determination was sensitive and reproducible with a range of 0.2-10 microM and a precision (coefficient of variation) of 2.43%.

Acetaldehyde↗
PubMed1989

[Observation of marginal leakage with 35SO4 =. 1. Method of testing for marginal leakage].

The purpose of this study was to develop a new observation method of marginal leakage of complete crowns with 35SO4 = labeled compound. The new point of this method was to use 15% gelatine solution, which was very effective to get clear autoradiograms. Once the labeled tracer penetrated marginal gaps, it didn't move away but stayed there. Complete crowns actually cemented to abutment teeth were treated using the new method, so that we could observe marginal condition more clearly than with the conventional method using various dyes or usual simple radioisotope. In this study, we found close relationship between film density of autoradiograms and marginal distance of gaps.

Autoradiography↗
PubMed1989

[Observation of marginal leakage with 35SO4 =. 2. Marginal leakage of complete crowns].

The purpose of this study was to observe marginal leakage of complete crowns cemented with zinc phosphate cement and adhesive cement as determined by RI. After repeating load the samples were placed in gelatine solution with 35SO4 = labeled compound. 1. Most of complete crowns cemented with zinc phosphate cement showed remarkable marginal leakage as long as the entire length of the interface. 2. Complete crowns cemented with adhesive cement showed very little marginal leakage, a maximum depth of 0.53 mm from crown margins. 3. The repeating load test manifested proper position of crown margin, that is, the crown margin should be placed at least 1 mm far from the dowel core margin using adhesive cement. 4. The marginal distance of gaps was presumed from autoradiograms by using the regressive formula calculated from the relationship between the distance of gaps and the film density in Part 1.

Adhesives↗
PubMed1989

[Study on composite resin cores. Part 2. Effect of pressing composite resin].

In this study, we investigated effects of pressing in building composite resin cores on compressive strength, retention of prefabricated post and sealing ability. 1. Compressive strength increased by pressing in composite resin cores. 2. Prefabricated post to the retentive forces was not influenced by pressing, but increased when bonding agent was used. 3. Pressing was very effective to improve sealing ability of composite resin to tooth structure. 4. Sealing ability of light-cured composite resin was not influenced by pressing but by curing types of bonding agent.

Composite Resins↗
PubMed1989

[Composite resin cores. Part 1. Comparison of various composite resin cores].

This study evaluated compressive strength, sealing ability and tensile bond strength of various materials of composite resin cores. 1. Compressive strength of the various materials, after they were placed in air for 24 hours, underwent thermal cycling testing, or were soaked in water for 2 weeks, ranged from 2000 kgf/cm2 to 2900 kgf/cm2. 2. The sealing ability after thermal cycling testing and being soaked in water for 2 weeks varied among the materials. 3. The bond strength of all composite resin core materials to dentin was less than 50 kgf/cm2. 4. In this study, no relationship was found between sealing ability and tensile bond strength.

Composite Resins↗
PubMed1989

[Study on gypsum hardener].

The purpose of this study was to search for an appropriate condition for shortening the treatment time of gypsum hardener, Plaster Aid. In order to keep the increased strength of plaster with this new hardener, compressive strength and dimensional change in various conditions of heating temperature, heating time and drying time were examined. The following results were obtained. 1. High compressive strength was maintained in the condition of 70 degrees C of heating temperature, with more than 15 minutes of heating time and more than 15 minutes of drying time. In this condition up to 90 minutes could be saved in comparison with the conventional method. 2. Plaster models had a tendency to shrink in the condition of 70 degrees C of heating temperature.

Calcium Sulfate↗