PubMed Health⌕ Search

Biomedical subjects

A Matsui

Publications and source records attributed to A Matsui.

At least 19 recordsLinked to original sources
PubMed1992

In situ detection of oxidative stress in rat hepatocytes.

In rat hepatocytes in primary culture incubated with nitro blue tetrazolium, formazan content was increased by addition of t-butyl hydroperoxide, a potent oxidant, in a dose-related manner, but not by addition of valinomycin, which kills hepatocytes through mitochondrial damage. This increment after t-butyl hydroperoxide addition was not seen in hepatocytes preincubated with deferoxamine mesylate, a ferric iron chelator which inhibits radical formation. Liver perfusion with nitro blue tetrazolium and t-butyl hydroperoxide in rats produced formazan deposition faintly on the surface of hepatocytes throughout the liver and prominently in the cytoplasm of some hepatocytes, which was attenuated when performed following deferoxamine mesylate perfusion. When liver perfusion with nitro blue tetrazolium was performed in carbon tetrachloride-intoxicated rats, formazan deposition appeared diffusely in hepatocytes in the centrilobular areas. Similar deposition was also observed on the surface and in the cytoplasm of hepatocytes in the periportal and mid-zonal areas in rats undergoing post-ischaemic reperfusion. Liver perfusion with nitro blue tetrazolium can detect in situ oxidative stress in hepatocytes and may be a useful tool for studying the role of lipid peroxidation in rat liver injury.

Animals↗
PubMed1992

Mutations within the S gene of hepatitis B virus transmitted from mothers to babies immunized with hepatitis B immune globulin and vaccine.

A variant of hepatitis B virus (HBV) having a specific mutation within the S gene has been found to infect vaccinees. To know whether similar variants were involved in Japan, we analyzed two cases of maternal transmission of HBV in infants immunized with hepatitis B immune globulin and hepatitis B vaccine. DNA clones of HBV S genes were propagated from patients and family members and sequenced. In one family, the DNA clones from the baby patient had a Gly-to-Arg mutation at the 145th codon of the S gene, whereas those from her mother had no such mutations. In the other family, all the DNA clones obtained from the two infected children had the 145th codon intact, but they had a missense mutation at the 126th codon of the S gene, causing an amino acid substitution of Asn for Thr or Ile. This same mutation was observed in 12 of 17 clones of DNA obtained from their mother. In comparison with the wild type HBV-derived hepatitis B surface antigen, the two types of S gene mutations, either at the 145th or the 126th codon, were associated with a significant decrease in the antigenicity of some determinants on the hepatitis B surface antigen, measured by MAb. Amino acid substitution at these sites, therefore, would have induced the escape from conventional vaccines that were S gene products of wild type HBV and also from hepatitis B immune globulin, whose main components were probably also antibodies against the S gene products expressed by wild type HBV.

Adult↗
PubMed1991

Identification of rat cDNA encoding hck tyrosine kinase from megakaryocytes.

A rat homologue of hck tyrosine kinase cDNA from a rat megakaryocyte library contains 1911 nucleotides with an open reading frame encoding 503 amino acids. The rat hck had distinct amino acid residues from the mouse homologue exhibiting 97.6% identity. The sequence contains the SH2 and SH3 regions that interact with cytoplasmic signaling proteins, the kinase domain including the nucleotide binding site and the autophosphorylation site, and the C-terminal Tyr-499 known as a negative regulator.

Amino Acid Sequence↗
PubMed1991

Thrombin induces a biphasic 1,2-diacylglycerol production in human platelets.

The 1,2-diacylglycerol (DAG) mass content was measured in thrombin-stimulated human platelets. Thrombin stimulates a biphasic accumulation of DAG, with an early phase reaching a peak at 10 s and a later phase reaching a peak at 2-3 min. The time course of first-phase DAG production corresponded well to that of Ins(1,4,5)P3 formation, which was rapid and transient. The second phase of DAG accumulation occurred after the level of Ins(1,4,5)P3 returned to nearly basal. Thrombin stimulated the decrease in PtdIns and phosphatidylcholine contents. The source of second-phase DAG was examined in platelets prelabelled with three radioactive fatty acids, i.e. arachidonic, palmitic and myristic. Thrombin stimulated the increase in radioactivity of DAG with decline of PtdIns in platelets labelled with [3H]arachidonic acid or [3H]palmitic acid, in which PtdIns was considerably labelled. In contrast, significant accumulation of [3H]DAG was not observed in [3H]myristic acid-labelled platelets, in which PtdIns was poorly labelled. In platelets prelabelled with [3H]inositol, an increase in InsP in response to thrombin was seen for more than 5 min. In contrast, upon stimulation, significant increases in [3H]phosphocholine and [3H]choline were not observed in [methyl-3H]choline-labelled platelets. Thrombin induced a small production of phosphatidylethanol, when ethanol was present during stimulation. However, the formation of DAG and phosphatidic acid was not significantly affected by ethanol. These results suggest that thrombin stimulates a biphasic accumulation of DAG, initially from PtdInsP2 and later from PtdIns in human platelets.

Arachidonic Acid↗
PubMed1991

Ultrasonographic findings and management of intrahepatic biliary tract abnormalities after portoenterostomy.

Ultrasonographic examinations was made in 24 children who had undergone a portenterostomy to correct extrahepatic biliary atresia. Abnormalities were observed in six patients. These were the result of ongoing inflammatory reactions because all had been suffering from cholangitis after surgery, and the size of the biliary tract structure changed in accordance with the occurrence and subsidence of the cholangitis. Ultrasonographic examination showed dilation of the intrahepatic bile duct in one patient and cystic lesions in five patients. Treatment included percutaneous transhepatic bile drainage for dilated bile ducts, alcohol injections for intrahepatic cysts, and reoperation for cysts in the porta hepatis. Treatment was not required for cysts in controllable cholangitis. The results of these approaches were excellent, indicating that they were of benefit in treatment intrahepatic abnormalities occurring after portoenterostomy.

Bile Ducts, Intrahepatic↗
PubMed1991

Hepatic cell necrosis with congenital heart disease in the newborn.

Hepatic cell necrosis is a recognized complication of circulatory failure. Histological examination of the adult liver in such cases reveals centrilobular necrosis and hepatic congestion. Two cases of hepatic cell necrosis in infancy are reported: a four-day-old girl with the hypoplastic left heart syndrome, and a nine-day-old girl with interruption of the aortic arch. In the former, midzonal hepatic necrosis (and not centrilobular necrosis) was demonstrated at autopsy. Both patients exhibited severe hepatic insufficiency, but hepatic function improved rapidly with treatment of the coexistent heart failure. It is suggested that there is milder form of hepatic cell necrosis than that previously reported in autopsies.

Female↗
PubMed1990

[Fever of unknown origin: re-evaluation of 67Ga scintigraphy in detecting causes of fever].

Radioactive gallium citrate has been known to accumulate not only in neoplasms but also in inflammatory foci, and thus widely used to find out pyrogenic lesions in cases of unexplainable prolonged fever. However, with developments and improvements of other imaging modalities, its diagnostic significance may have changed. To probe that issue, recent 65 scans for the patients with fever of unknown origin were reviewed retrospectively. Of these, 56 had sufficient clinical assessment and laboratory examinations to evaluate causative illnesses. Gallium images of 33 patients were interpreted as positive. Local inflammatory lesions were detected in 23 cases, with lung tuberculosis, urinary tract infection, and inflammatory joint diseases as prevalent final diagnoses. Pyogenic abscesses, though popular in the literatures on fever of unknown origin, were found in only 2 cases in our present series. This seemed to be due to earlier detection of affected sites by other imaging technics. Osteomyelitis, other major cause of fever in the past, was not found this time, probably owing to wide use of antibiotics. Besides localized diseases, seven cases of generalized disorders were found. There were 3 patients with hematological malignancies, 3 with systemic autoimmune diseases, and 1 with severe infectious mononucleosis. There were three false positive cases; intestinal gallium radioactivity in 2 cases and physiological pulmonary hilar accumulation in 1 were erroneously read as abnormal. Of 23 cases with negative gallium scan, no definite cause of fever were found in 19; twelve patients had spontaneous reduction of fever, 2 did so with antibiotics, and 5 with corticosteroids. False negative cases were; two with urinary tract infection on antibiotics, one with bacterial meningitis, and one with polyarteritis nodosa. Our results reconfirmed the excellent sensitivity and accuracy of gallium scan in the diagnosis of fever of unknown origin. In addition to the detection of focal inflammations, it may sometimes contribute to an early diagnosis of unexpected systemic diseases. From the results obtained, it is advisable that, in patients with fever of unknown origin, this test should be done early in diagnostic schedule and before administration of drugs that may mask potential sites of abnormal accumulation.

Adolescent↗
PubMed1990

Nonsegmental inhibition of rat dorsal horn neurons by innocuous stimulation.

In rats anesthetized with thiamylal sodium, responses of spinal cord dorsal horn neurons to noxious skin heating of the tail were recorded by extracellular microelectrodes. Inhibition of these responses by innocuous mechanical stimulation (light brushing) of the ipsilateral forelimb was assessed. Short-lasting application (3 min, or less) of light brushing did not inhibit neuronal responses to noxious heating. Long-lasting application (5 min, or more) inhibited responses of these neurons to noxious stimulation. The results indicate that, in the anesthetized rat, remotely applied innocuous cutaneous stimuli can inhibit nociceptive responses of dorsal horn neurons, if applied for a sufficiently long time.

Afferent Pathways↗
PubMed1990

Inhibition of nociceptive responses of wide-dynamic-range neurons by peripheral nerve stimulation.

Of 107 neurons from the sacral and coccygeal levels of the spinal cord in anesthetized intact rats examined, 62 wide-dynamic-range (WDR) neurons that responded to noxious heating of the tail were recorded. On the basis of their inhibitory responses through A-beta or A-delta afferent fibers to noxious stimulation, these neurons were classified into one of the following three types: Type I--neurons inhibited only by A-beta afferent nerve impulses; Type II--neurons inhibited only by A-delta afferent nerve impulses; Type III--neurons inhibited by both. The present results are compared with previously reported behavioral results.

Animals↗
PubMed1990

Dental cutting behaviour of mica-based and apatite-based machinable glass-ceramics.

Some recently developed industrial ceramics have excellent machinability properties. The objective of this study was to evaluate the dental cutting behaviour of two machinable glass-ceramics, mica-containing Macor-M and apatite- and diopside-containing Bioram-M, and to compare them with the cutting behaviour of a composite resin typodont tooth enamel and bovine enamel. Weight-load cutting tests were conducted, using a diamond point driven by an air-turbine handpiece, While the transverse load applied on the point was varied, the handpiece speed during cutting and the volume of removal upon cutting were measured. In general, an increase in the applied load caused a decrease in cutting speed and an increase in cutting volume. However, the intensity of this trend was found to differ between four workpieces. Cutting Macor-M resulted in the second-most reduced cutting speed and the maximum cutting volume. Cutting Bioram-M gave the least reduced cutting speed and the minimum cutting volume. It was suggested that two machinable glass-ceramics could be employed as typodont teeth. This study may also contribute to the development of new restorative dental ceramic materials, prepared by machining.

Aluminum Silicates↗
PubMed1990

Studies on fracture toughness of dental ceramics.

One important mechanical property of dental ceramics is fracture toughness, KIC, which represents the serviceability in the oral cavity, such as the resistance to marginal fracture. KIC values of several dental ceramics, natural tooth enamel and industrial ceramics were examined by use of the indentation microfracture (IM) method. This technique was based on the series of radial cracks emanating from the corners of the Vickers indentation. It was observed that appropriate load levels should be selected on each specimen to induce radial/median cracks. For feldspatic dental porcelains, larger loads of 10, 20 and 30 kg were needed to determine their KIC values in the range 1.5-2.1 MN.m-3/2. For natural tooth enamel and a new apatite-based castable glass-ceramic, a smaller force of 1 kg was sufficient to decide the respective KIC values of about 0.9 and 1.8 MN.m-3/2. The KIC values of most dental ceramics examined were slightly higher than that of soda lime glass, but less than one-third that of zirconia. It was confirmed that the IM method is simple and cost-effective for evaluation of KIC of dental ceramics.

Aluminum Silicates↗
PubMed1990

Effects of the diamond grit sizes of the commercial dental diamond points on the weight-load cutting of bovine enamel and glass-ceramic Typodont teeth.

To evaluate the effect of the diamond grit size of commercial dental diamond points on the dental cutting, we conducted weight-load cutting tests on bovine enamel and glass-ceramic typodont teeth using 3 different diamond grit sizes and air-bearing and ball-bearing air-turbine driven handpieces. With the transverse load applied on the diamond point varied between 20 and 80 g, we measured rotational cutting speed and cutting volume. Generally, increases in applied load caused decreases in rotational cutting speed and increases in cutting volume. The intensity of this trend, however, differed between grit sizes. Regular grit diamond points most strongly showed this tendency, while super-fine grit diamond points were least affected. Fine grit diamond points behaved in a manner similar to regular grit points.

Animals↗