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Biomedical subjects

K Okazaki

Publications and source records attributed to K Okazaki.

At least 343 records · Page 19Linked to original sources
PubMed1990

[The effect of hypocapnia and hypercapnia on myocardial oxygen tension in hemorrhaged dogs].

To investigate the effect of carbon dioxide on the myocardial oxygenation during hemorrhagic shock, myocardial oxygen tension and coronary flow were measured during normocapnia, hypocapnia and hypercapnia. Eight adult mongrel dogs were anesthetized with pentobarbital, intubated and ventilated mechanically with 100% oxygen to maintain normocapnia. Then their chest was opened. An electromagnetic blood flow probe was applied on the left anterior descending artery. Two pairs of combined polarographic needle electrodes were carefully inserted, one pair in the epicardial layer, and the other in the endocardial layer of the heart. The animals were progressively bled in increments of 35-40ml.kg-1 (body weight). Hypocapnia was produced by increasing respiratory rate, and then normocapnia and hypercapnia were induced by adding the exogenous carbon dioxide. Hypocapnia decreased the coronary flow, and myocardial oxygen tension in outer and inner layer. On the contrary, hypercapnia increased them. It is possible that hypocapnia may compromise the oxygenation of the myocardium during hemorrhagic shock.

Animals↗
PubMed1990

[Fracture toughness of human enamel irradiated by CO2 laser].

The fracture toughness (KIC) of human enamel irradiated by CO2 laser was examined by means of indentation microfracture method (IM method). The irradiation of laser from 1.5 watt (16 J/cm2) to 12.3 watt (133 J/cm2) was applied to enamel for 0.2 s, and the diamond cone of micro vickers hardness tester was pressed down by the 2.45 N (250 gf) under ordinary circumstances. At the irradiated spot, KIC was 0.24-0.86 MPam1/2 and Hv was 3.6 x 10(3)-4.3 x 10(3)MPa (370-440). At the non-irradiated spot, KIC was 0.83-0.9 MPam1/2 and Hv was 3.9 x 10(3)-4.3 x 10(3)MPa (400-440). A decreasing tendency of KIC was seen in all irradiated spots. The marked decrease of KIC started at the irradiation of 4.4 watt (47 J/cm2) and the rate of decrease was 22%, and 54% when exposed to the irradiation of 5.7 watt (61 J/cm2). The rate of the lowering of the KIC of 0.05 seconds' irradiation x 4 times was less than that of 0.2 s x 1 time, while cumulative total irradiation energy was equal. The measurement of KIC by the low force of 0.98 N (100 gf) seemed to be possible when KIC was 0.41 MPam1/2 and less.

Dental Enamel↗
PubMed1990

[Fatigue of dental zinc phosphate cement].

The fatigue characteristics of a zinc phosphate cement were examined. Using a split mould made of stainless steel, 12 mm x phi 6 mm column shape specimens were prepared. Fatigue tests were done by loading partially repeated pulsating diametrical tensile stress of 1-20 Hz, minimum stress was 0.2 MPa (2.0 kgf/cm2) and maximum stress was 3.5-5.4 MPa (36-55 kgf/cm2). During testing, the specimen was kept under distilled water. The existence of a fatigue was confirmed and there were marked signs of fatigue on the fracture surface. The relation between maximum stress and the number of cycles to fracture (S-N diagram) was obtained. Therefore the following equation and fatigue parameter (n) were deduced. logS + 0.0775.logN = 0.8931 n = 12.9 The fatigue characteristics depended on the frequency, that is, a time to fracture was shorter at the loading frequency of 20 Hz than that of 1 Hz.

Materials Testing↗
PubMed1990

Congenital hypoplasia of the dorsal pancreas: with special reference to duodenal papillary dysfunction.

We report a case of dorsal pancreatic hypoplasia complicated with atresia of the vagina, type-A chronic atrophic gastritis, duodenal papillary dysfunction, and insulin-requiring diabetes mellitus, in a 32-yr-old woman. The laboratory data showed elevated hepatobiliary enzymes. Endoscopic retrograde cholangiopancreatography (ERCP) revealed a slightly dilated common bile duct and a short major pancreatic duct connected with a minor pancreatic duct. Ultrasonography and computerized tomography could not identify any pancreatic tissue in the region of the body or tail of the pancreas. The pancreatic tissue weight calculated by the serial thin slice of computerized tomography was 43.1 g, approximately 45% of the standard Japanese adult pancreas. Reevaluated pancreatic exocrine function based on this weight showed a hypersecretory state. The pancreatic ductal pressure was slightly increased, and the motility of the sphincter of Oddi (SO) was abnormal when measured with a 4Fr. microtransducer inserted through a duodenoscope. These findings suggest that dysfunction of the sphincter of Oddi may play some role in the pathophysiology in the hypoplasia of the dorsal pancreas and pancreaticobiliary diseases associated with it.

Adult↗
PubMed1990

Mutagenicity of nitrite-treated soy sauce in Chinese hamster V79 cells.

Mutagenicity of 4 kinds of Japanese soy sauce and tyramine, which is a precursor of a mutagen (3-diazotyramine) and present in soy sauce, after nitrite treatment under a yellow lamp was studied in Chinese hamster V79 cells with 6-thioguanine (TG) as a selective marker. The frequencies of mutation caused by nitrite-treated samples of soy sauce increased in the V79 cells in a dose-dependent manner. Four kinds of nitrite-treated soy sauce induced 139 to 473 TG-resistant mutants per 10(5) clonable cells per milliliter of soy sauce equivalent in the cells. Nitrite-treated tyramine was also mutagenic for the cells; it induced 8.6, 13.3, and 18.3 TG-resistant mutants per 10(5) clonable cells at concentrations of 20 micrograms, 56 micrograms, and 112 micrograms, respectively.

Animals↗
PubMed1990

[Specific immune response to pancreas antigen (PA3) in chronic pancreatitis and Sjögren syndrome].

The pancreas antigen (PA3) was prepared by an interspecies cross-reactive monoclonal antibody (SP3-1, IgM), which reacts with duct cells of multiple exocrine organs. Cell-mediated immunity to PA3 was examined using a lymphocyte proliferation test, and serum antibody to PA3 was measured by radioimmunoassay. Lymphocyte sensitization and serum antibody to PA3 were demonstrated in patients with idiopathic chronic pancreatitis (CP) and Sjögren syndrome with high rate and high titer. In normal controls and patients with alcoholic CP, stone related CP, PBC, SLE and chronic thyroiditis, they were rarely detected. The antigen detected by serum antibodies in patients with idiopathic CP and Sjögren syndrome was 60 kDa on Western immunoblot. These results revealed a possibility that PA3 was the target antigen for immune response in the pathogenesis of idiopathic CP and/or Sjögren syndrome.

Antigens, Neoplasm↗
PubMed1989

Reflex regulation of the sphincter of Oddi by intrapancreatic ductal pressure in the Japanese monkey.

Japanese monkey has a common ampullary channel. By a continuous injection of sterile saline (1 mL/min) into the pancreatic main duct, the pancreatic main ductal pressure increased from 8.4 +/- 1.0 (mean +/- SD) to a plateau level (16-25 mmHg) in 5 Japanese monkeys. The frequency and amplitude of the slow wave in electromyography of the sphincter of Oddi (SO) were significantly decreased from 14 to 2/min and 0.06 to 0.04 mV (p less than 0.01), and the frequency of the spike component significantly decreased from 53 to 14/min (p less than 0.05). As soon as infusion of saline ceased, the electromyography recovered to the original level. The mean value of the minimum loading pressure affecting myoelectrical activities of the SO was 19.8 +/- 3.0 mmHg. When the pancreatic duct was obstructed at the head, there was no significant change in the SO myoelectrographic activities in spite of increased pancreatic ductal pressure by infusion. These findings suggest that a homeostatic mechanism of pancreatic ductal pressure exists when the activity of the SO is regulated by the distending pressure in the pancreatic ductal system. This reflex regulation seemed to be mediated by the distension of the ampullary duct itself.

Ampulla of Vater↗
PubMed1989

Evolutionary pathways of the PA genes of influenza A viruses.

Nucleotide sequences of the PA genes of influenza A viruses, isolated from a variety of host species, were analyzed to determine the evolutionary pathways of these genes and the host specificity of the genes. Results of maximum parsimony analysis of the nucleotide sequences indicate at least five lineages for the PA genes. Those from human strains represent a single lineage, whereas the avian genes appear to have evolved as two lineages--one comprising genes from many kinds of birds (e.g., chickens, turkeys, shorebirds, and ducks) and the other comprising only genes from gulls. H3N2 swine influenza virus PA genes are closely related to the currently circulating duck virus PA gene. By contrast, the H1N1 swine and equine virus PA genes appear to have evolved along independent lineages. Comparison of predicted amino acid sequences disclosed 10 amino acid substitutions in the PA proteins of all avian and H3N2 swine viruses that distinguished them from human viruses. The H1N1 swine viruses seem to be chimeras between human and avian viruses and they contain 8 amino acids not shared by other viruses. The equine viruses also appear to show their own amino acid substitutions. These findings indicate that the PA genes of influenza A viruses have evolved in different pathways defined by apparently unique amino acid substitutions and host specificities. They also indicate that influenza A viruses have been transmitted from avian to mammalian species.

Amino Acid Sequence↗
PubMed1989

An enzyme immunoassay for human lymphotoxin.

A highly sensitive and specific enzyme immunoassay (EIA) for human lymphotoxin (hLT) has been developed. The assay is based upon a sandwich system employing two kinds of anti-hLT antibodies with neutralizing activity. One of them was mouse monoclonal antibody raised against Escherichia coli-derived recombinant hLT with a deletion of 20 amino-terminal amino acids and used as labelled antibody. The other was rabbit antibody raised against the carboxyl-terminal portion of hLT and used as solid-phase antibody. The EIA employing such a combination was able to detect less than 50 pg/ml of hLT, showing that this method was approximately 5-10 times higher sensitivity than the conventional bioassay employing L929 cell-lysis. The mean recovery of hLT added to serum specimens was 101% and the coefficients of variation were 3.3-7.8% (intra-assay) and 2.9-17.2% (interassay). There was a good correlation between the present EIA and the bioassay (r = 0.93).

Animals↗
PubMed1989

High level expression of a synthetic gene coding for IgG-binding domain B of Staphylococcal protein A.

A gene coding for one of the IgG-binding domains of Staphylococcal protein A, designated domain B, was chemically synthesized. This gene was tandemly repeated to give dimeric and tetrameric domain B genes by the use of two restriction enzymes which gave blunt ends. The genes were highly expressed in Escherichia coli to afford a large amount of dimeric and tetrameric domain B proteins. The single domain B protein was efficiently produced as a fusion protein with a salmon growth hormone fragment. The fusion protein was converted to monomeric domain B by cyanogen bromide cleavage. The CD spectra of the monomeric, dimeric and tetrameric domain B proteins were essentially the same as that of native form protein A, showing that their secondary structures were very similar. The dimeric and tetrameric domain B proteins formed precipitates with IgG as protein A. This system permits the efficient production of mutated single and multiple IgG-binding domains which can be used to study structural changes and protein A-immunoglobulin interactions.

Amino Acid Sequence↗
PubMed1989

Lipolytic activity of Campylobacter pylori: effect of sofalcone.

The lipolytic activity of Campylobacter pylori capable of gastric mucosal lipid degradation was investigated. The colonies of bacteria, cultured from antral mucosal biopsy specimens of patients undergoing endoscopy, were washed with saline and passed through a sterilization filter; the filtrate was examined for lipase and phospholipase A activities, using glycerol trioleate and dipalmitoyl phosphatidylcholine as substrates. The obtained results revealed that both enzymes are present in the C. pylori filtrate. The enzymes exhibited optimal activity at 37 degrees C and the pH range of 7.0-7.4. The major product of the triglyceride degradation was glycerol monoleate, while lysophosphatidylcholine resulted from the degradation of phosphatidylcholine. The lipase activity of the C. pylori filtrate was inhibited by an antiulcer drug, sofalcone, which at a concentration of 200 micrograms/ml caused a 43% reduction in the triglyceride hydrolysis. The sofalcone, however, showed only marginal, if any, inhibitory activity toward C. pylori phospholipase A. The results suggest that C. pylori infection may be detrimental to the integrity of gastric mucosal lipids.

1,2-Dipalmitoylphosphatidylcholine↗
PubMed1989

Nature of the enhancement of the protective qualities of gastric mucus by sucralfate.

The effects of intragastric administration of an antiulcer drug, sucralfate, on the content, composition and physical properties of the mucus component of gastric mucosal barrier were investigated. The experiments were conducted with two groups of rats in which one group received twice daily for five consecutive days a dose of 100 mg sucralfate, while the control group received daily doses of saline. The animals were sacrificed 16 h after the last dose, their stomachs dissected and the mucosa subjected to measurements of the adherent mucus gel dimension and mucin content, evaluation of its viscosity, H+ retardation capacity and hydrophobicity, and analysis of its components and molecular form distribution of elaborated mucin. The results revealed that sucralfate elicited only a minor (8%) increase in mucus gel dimension, while sulfo- and sialomucin contents of the gel increased by 63 and 81%, respectively. The changes in mucus gel mucin content with sucralfate were accompanied by a slight (9.5%) increase in mucus H+ retardation capacity, 1.9-fold increase in viscosity, and a 60% increase in the gel hydrophobicity. Chemical analyses indicated that the mucus elaborated in the presence of sucralfate exhibited 14% lower protein content and 62% higher content of carbohydrate than that of control, displayed similar levels of total lipids and covalently bound fatty acids, but its neutral lipid content was significantly higher. Furthermore, the gastric mucus of the sucralfate group showed a marked increase in the proportion of the high-molecular-weight form of mucin, while the low-molecular-weight form predominated in the control group. The results indicate that the protective qualities of sucralfate lie mainly in its ability to enhance the gastric mucus gel viscosity, hydrophobicity, content of mucin and its proportion in the high-molecular-weight form.

Animals↗
PubMed1989

Preparation and evaluation of albumin microspheres and microcapsules containing cisplatin.

Albumin microspheres and microcapsules containing cisplatin (CDDP) were prepared and tested as chemotherapeutic agents for the treatment of hepatocellular carcinoma. CDDP albumin microspheres were prepared by hardening with glutaric aldehyde in accordance with the method to prepare W/O emulsion. On the other hand, microcapsules were prepared by formation of a coacervate by the phase isolation method. CDDP albumin microspheres and microcapsules thus prepared were sieved and sterilized by dry heat at 135 degrees C for 4h prior to use. The content and release of CDDP were determined. The CDDP contents for albumin microspheres and microcapsules were found to be 9.2% and 33.3%, respectively. Release of CDDP in vitro was found to be significantly different between the two formulations. CDDP release in vivo was also investigated by injecting albumin microspheres and microcapsules into the hepatic artery of adult dogs. The blood CDDP concentrations after injection of both formulations were lower than those noted after injection of CDDP injectable solution, indicating that CDDP might be accumulated in the liver at a higher concentration and that use of the two formulations might result in alleviation of CDDP side effects.

Albumins↗
PubMed1989

Preparation and release characteristics of cisplatin albumin microspheres containing chitin and treated with chitosan.

Cisplatin (CDDP) containing albumin microspheres and microcapsules incorporating biodegradable macromolecules, chitin and chitosan, were prepared, and their CDDP content and releasing ability and susceptibility to various enzymes were examined. Chitin was incorporated during preparation of the microspheres, while chitosan was used to treat preformed microspheres. CDDP content was remarkably increased by chitin; when chitin was incorporated at a concentration of 1.5%, the CDDP content of the microspheres was found to be 16.2% (1.8 times that with no addition of chitin). CDDP release was suppressed by chitin and chitosan. The 50% CDDP release time was about 1.5 h when no chitin was added, but about 16 h was required when chitin was incorporated into the microspheres at a concentration of 1.5%. Chitin and chitosan suppressed the decomposition by protease. The microspheres treated with 70% deacetylated chitosan showed the greatest susceptibility to lysozyme. In conclusion, CDDP release can be controlled by the use of chitin or chitosan, and the microspheres should show no immunogenicity in vivo because of their susceptibility to lysozyme.

Albumins↗
PubMed1989

A comparison of polypeptides and restriction endonuclease sites of BHV-1 isolates and identification of IPV virus in Japan.

Bovine herpesvirus 1 (BHV-1) isolates from respiratory tract and from vagina of bovine in Japan were analyzed by SDS-polyacrylamide gel electrophoresis (SDS-PAGE) and the DNA restriction endonuclease cleavage pattern, and compared with European BHV-1 strains. Both protein profile and DNA cleavaged pattern of BHV-1 isolates from respiratory tract were the same as those of European infectious bovine rhinotracheitis (IBR) virus, whereas the protein profile and DNA cleavage patterns of one isolate (M1) from vagina was the same as those of the European infectious pustular vulvovaginitis (IPV) virus. The facts indicate that IPV virus has existed in Japan.

Animals↗
PubMed1989

[Effects of carbon dioxide (hypocapnia and hypercapnia) on tissue blood flow and oxygenation of liver, kidney and skeletal muscle in the dog].

UNLABELLED: We investigated the effects of carbon dioxide on the splanchnic visceral organs (liver and kidney) as well as skeletal muscle in the anesthetized dog. Thirty two adult mongrel dogs were anesthetized with sodium pentobarbital, intubated and ventilated mechanically with 100% oxygen to maintain normocapnia. After laparotomy, miniature Clark-type polarographic oxygen electrodes were placed on the surfaces of liver, kidney and rectus femoris muscle. Electromagnetic blood flow (BF) probes were also applied to hepatic artery (HA), portal vein (PV), left renal artery (RA) and left femoral artery (FA). After a stable normocapnic ventilation, the hypocapnia was produced by increasing respiratory rate, and the hypercapnia was induced by adding the exogenous carbon dioxide. RESULTS: Hyperventilation resulted in a significant decrease in HABF, PVBF, liver surface PO2 and kidney surface PO2 in parallel with the decreased PaCO2, but these parameters increased dose dependently when the carbon dioxide was added to the inspired gas (hypercapnic hyperventilation). On the contrary, FABF and skeletal muscle surface PO2 increased by hypocapnia and decreased during hypercapnia. Neither PaCO2 or cardiac output showed any significant change during the entire experiment. Arterial PCO2 appears to exert significant effects on both splanchnic and skeletal muscle perfusion as well as corresponding changes in tissue oxygenations. It is possible that injudicious and prolonged hypocapnic hyperventilation may seriously compromise splanchnic organ perfusion and oxygenation.

Animals↗
PubMed1989

[The effects of hypocapnia and hypercapnia on tissue surface PO2 in hemorrhaged dogs].

To investigate the effects of carbon dioxide on the local blood flow during hemorrhagic shock, the tissue surface PO2 of liver, kidney and femoral muscle was measured during normocapnia, hypocapnia and hypercapnia. Eight adult mongrel dogs were anesthetized with pentobarbital, intubated and ventilated mechanically with 100% oxygen to maintain normocapnia. After laparotomy, miniature clark-type polarographic oxygen electrodes were placed on the surface of the liver, kidney and femoral muscle. The animals were hemorrhaged via arterial catheter to a mean arterial blood pressure of 50mmHg. The hypocapnia was produced by increasing respiratory rate and the hypercapnia was induced by adding the exogenous carbon dioxide. Hypocapnia decreased the liver and kidney surface PO2, and increased the muscle surface PO2. On the contrary, hypercapnia increased the liver and kidney surface PO2 and decreased the muscle surface PO2. So, it is possible that hypocapnia may compromise the oxygenation of the liver and kidney in the hemorrhagic shock.

Animals↗