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Biomedical subjects

S Iida

Publications and source records attributed to S Iida.

At least 307 records · Page 17Linked to original sources
PubMed1988

Automated synthesis system with computer control for the production of [1-11C]fatty acids.

To accommodate the increasing need for [1-11C]fatty acids for use in routine medical studies and the large amounts of radioactivity required, a more advanced automated synthesis system for the preparation of [1-11C]fatty acids has been constructed. The synthesis of [1-11C]fatty acids has been completely automated using a new separation unit (isobaric Sepaltor) for the extraction procedure, which had caused some difficulties with automation. The yield of [1-11C]palmitic acid was 20-30 mCi, and that of 3-methyl [1-11C]heptadecanoic acid was 2-7 mCi. The time required for the synthesis was less than 30 min from the start of the 11CO2 trapping. This system has been used for more than 20 preparations of [1-11C]palmitic acid and more than 20 preparations of 3-methyl [1-11C]heptadecanoic acid.

Carbon Radioisotopes↗
PubMed1988

In vitro evaluation of iris chafe protection afforded by hydrophilic surface modification of polymethylmethacrylate intraocular lenses.

An in vitro iris chafe test was developed to evaluate possible differences in abrasive interaction of various intraocular lens (IOL) materials with the posterior surface of the iris. The materials that were compared in initial tests with rabbit irides were high molecular weight polymethylmethacrylate (PMMA), the primary IOL material in current use, and surface-modified PMMA, which had a permanent, chemically bound, hydrophilic, polymer surface. Scanning electron microscopy, light microscopy, and examination of histological sections were used to assess tissue damage. A "window defect" type of abrasive damage was observed by light microscopy for PMMA lenses and is very similar in appearance to that seen for iris abrasion by human implants when viewed in vivo in slitlamp examinations. Results for both pigmented and albino rabbit irides indicate a reduction in abrasive insult to the external iris basement membrane and underlying pigment epithelium by the hydrophilic surface modification of PMMA. These results are consistent with our observation of a major reduction in corneal endothelium damage on contact with the hydrophilic surface-modified PMMA as compared with PMMA itself. This in vitro iris abrasion test, therefore, appears to be a useful technique for future evaluation of IOL surface properties.

Animals↗
PubMed1988

Calcium binding to troponin C. II. A Ca2+ ion titration study with a Ca2+ ion sensitive electrode.

The effects of pH,Mg2+, and ionic strength on Ca2+ binding to rabbit skeletal troponin C were studied by using a Ca2+ sensitive electrode. Troponin C has two high affinity and two low affinity sites and the Ca2+ affinity of both sites was increased by increasing pH in a pH range from pH 5.6 to 10.4. The affinity was decreased by increasing ionic strength. The change of the Ca2+ affinity can be explained by the electrostatic interaction between Ca2+ and the protein. At alkaline pH, the four Ca2+ binding sites bind Ca2+ with the same affinity and the distinction between the high and the low affinity sites vanished. This result shows that the difference of the Ca2+ affinity is owing to differences of the secondary or the tertiary structure of the Ca2+ binding sites, not owing to a difference of the primary structures of the Ca2+ binding sites. The two high affinity sites bound two Ca2+ ions cooperatively in neutral pH. The cooperativity was diminished at both acidic and alkaline pH. Mg2+ ion decreased the affinity of the low affinity sites.

Animals↗
PubMed1988

Histological changes in the liver and portal hypertension subsequent to repeated intraportal injections of killed E. coli in the dog.

The etiology of idiopathic portal hypertension (IPH) is not known. To obtain clues to the pathogenesis, an attempt was made to produce a hepatic lesion similar to that in IPH by repeated injections of aggregated killed non-pathogenic E. coli directly into the portal vein. In the treated dogs, histology of the liver showed dense fibrosis in the portal tract and an aberrant vasculature around the portal area after 1 month. Portal pressure was elevated and middle-to-small-sized portal branches were decreased in number as studied by portography. These changes closely mimic those seen in human IPH. The possibility is discussed that chronic entrance of an antigen such as bacteria from the intestine to the portal venous system plays an etiologic role in IPH.

Animals↗
PubMed1988

Plasma abnormal prothrombin levels in patients with small hepatocellular carcinoma.

The diagnostic value of plasma abnormal prothrombin (PIVKA-II) measurements in detecting relatively small hepatocellular carcinomas (HCC), less than 5 cm in diameter, was compared with that of serum alpha-fetoprotein (AFP) determinations. Among 18 patients with relatively small hepatocellular carcinoma (HCC), abnormal PIVKA-II values were found in only three (16.6%). Highly elevated serum AFP levels (greater than 200 ng/ml) relatively specific for HCC were seen also in three patients. However, nonspecific elevation of PIVKA-II in patients with liver cirrhosis not accompanied by HCC was much less than that of AFP. Although complementary, both tests appear to be of limited value in early detection of HCC, indicating that searches for other markers are necessary, to allow early detection of small HCC.

Aged↗
PubMed1988

The seroprevalence of anti-HTLV-1 antibodies in patients with various liver diseases.

The prevalence of antibodies to human T-cell leukemia virus type 1 (HTLV-1), which is linked to the etiology of adult T-cell leukemia (ATL), was examined in 380 patients with various liver diseases in Kumamoto Prefecture, southwestern Japan, which is one of the most endemic area for HTLV-1. Eighteen patients with acute hepatitis (AH), 201 chronic hepatitis (CH), 93 liver cirrhosis (LC) 40 hepatocellular carcinoma (HCC) and 28 with other liver diseases were examined. Among these patients, 110 patients had histories of blood transfusion. HTLV-1 specific antibodies were assayed by the ELISA method and the Western blotting method. The rate of positive reaction was 8.9% in all, 5.6% in AH, 6.0% in CH, 10.8% in LC, 17.5% in HCC and 14.3% in the cases of other liver diseases. The prevalence of anti-HTLV-1 antibodies in about 62,000 healthy blood donors in this area was 4.7%. The overall sero-prevalence in the patient group was significantly higher (p less than 0.001), than in healthy blood donors, particularly in the LC and HCC groups. Although the occurrence increased with age, no difference between sex was observed. Patients who had received blood transfusions were found to have a higher rate (17.2%), than those who had not (5.9%), and healthy blood donors. No difference was found between the two groups regarding family history of liver disease. This study indicates that blood transfusions may be an important route to the HTLV-1 infection.

Adolescent↗
PubMed1988

Halothane hepatotoxicity and reductive metabolism of halothane in acute experimental liver injury in rats.

Reductive metabolism of halothane was measured after acute liver injury induced by galactosamine (1.0 g/kg, IP) in rats. On the seventh day of liver injury, when previously elevated serum alanine aminotransferase levels had returned to near normal range, anaerobic release of fluoride from halothane by hepatic microsomes, which appears to reflect the reductive pathway of halothane metabolism, was still remarkably decreased (1.36 +/- 0.56 nmol/mg protein/h vs 5.88 +/- 0.58 in controls, P less than 0.001). In another set of experiments, rats (n = 8) given galactosamine 7 days earlier and saline-treated control rats were given halothane anesthesia (1.0%) under mildly hypoxic conditions (F1O2 0.14). In saline controls, halothane anesthesia resulted in a mild but statistically significant increase in serum alanine aminotransferase levels (32 +/- 4 vs 59 +/- 6 U/ml, P less than 0.001). In contrast, serum levels of this enzyme were not changed by halothane anesthesia in galactosamine-treated rats (45 +/- 3 vs 49 +/- 4 U/ml). Although care should be taken in extrapolating the importance of these animal data to humans, the results of this study suggest that halothane hepatotoxicity can be attenuated in the presence of minor liver injury as a result of decreased hepatic biotransformation of the anesthetic. The data support the view that halothane anesthesia is not necessarily contraindicated in subjects with impaired liver function.

Alanine Transaminase↗
PubMed1988

Role of intrahepatic portal-systemic shunts in the reduction of portal blood supply to liver cells in cirrhosis.

To assess the role of intrahepatic portal-systemic shunts in the reduction of portal blood supply to the liver cells in cirrhosis, we measured portal venous flow (blood flow in the portal trunk) by the pulsed Doppler flowmeter and intrahepatic portal-systemic shunt index from the counts over the lungs and liver in both the anterior and posterior projections after instillation of 99mTc-macroaggregated albumin in the portal vein, and calculated portal sinusoidal flow (blood flow into the sinusoids via the portal vein), using the equation, (sequence; see text) in 47 patients with posthepatitic cirrhosis, and measured portal venous flow in 63 healthy adults in whom portal sinusoidal flow should be comparable to portal venous flow. Portal sinusoidal flow was significantly reduced in cirrhotics with an intrahepatic portal-systemic shunt index averaging 24%, whereas portal venous flow was similar in the cirrhotics and control. There was a significant inverse correlation between intrahepatic portal-systemic shunt index and portal sinusoidal flow. When cirrhotics were divided into three stages, based on Child's grading, intrahepatic portal-systemic shunt index was significantly increased in the group order of Child's A (8 +/- 9%), Child's B (27 +/- 22%), and Child's C patients (46 +/- 19%), and portal sinusoidal flow was decreased in the same order. Portal sinusoidal flow was significantly reduced in Child's B and Child's C patients, but not in Child's A patients, compared with the control. In conclusion, intrahepatic portal-systemic shunts may play a role, at least in part, in the reduction of portal blood supply to the liver cells in patients with advanced stage of posthepatitic cirrhosis when large intrahepatic portal-systemic shunts develop.

Adult↗
PubMed1987

The long-term survival of patients with carcinoma of the main hepatic duct junction.

Carcinoma of the main hepatic duct junction tends to invade extensively the bile ducts and hepatic parenchyma, although dissemination is rarely seen. Therefore, extensive resection of the bile ducts combined with hepatic resection is the procedure of choice for treating this disease. From January 1973 to January 1987, 23 of 41 patients underwent resection, giving a resectability rate of 56%. One patient died postoperatively, yielding an operative mortality rate of 4.3%. The 5-year actuarial survival rate is 29.8%. Three patients are now alive and well 6 years and 9 months, 5 years and 10 months, and 5 years and 5 months after the operation. One additional patient who underwent resection in an affiliated hospital has done well for 8 years and 8 months. The results from these four patients treated by curative resection support a strategy featuring curative resection with aggressive surgery.

Aged↗
PubMed1987

The acceleration of Na+,K+-ATPase activity by ATP and ATP analogues.

Since Na+,K+-ATPase (EC 3.6.1.3) of pig kidney modified with a fluorescent sulfhydryl reagent, N-[p-(2-benzimidazolyl) phenyl]maleimide, at Cys-964 of the alpha-chain showed ATP-dependent, reversible, and dynamic fluorescence changes (Nagai, M., Taniguchi, K., Kangawa, K., Matsuo, S., Nakamura, S., and Iida, S. (1986) J. Biol. Chem. 261, 13197-13202), we studied the conformational change during Na+,K+-ATPase reaction using the modified enzyme. The addition of K+ to the enzyme increased the fluorescence intensity to 2% in the presence of 160 mM Na+ and 3 mM Mg2+ (K0.5 = 16.4 mM). Addition of low concentrations of ATP immediately increased the intensity to 3.2% (K0.5 less than 0.1 microM) to accumulate fully K+-bound enzyme in the presence of 43 mM K+ with Na+ and Mg2+, but further addition of higher concentrations of ATP diminished the increase (K0.5 = 120 microM). After exhaustion of ATP, the fluorescence intensity decreased to -0.4% (K0.5 = 0.3 microM) and -2% (K0.5 = 20 microM), respectively, in the presence of low and high concentrations of ADP produced from ATP. High concentrations of ATP accelerated Na+,K+-ATPase activity with a simultaneous increase in the amount of ADP-sensitive phosphoenzyme irrespective of the modification. Adenylyl imidodiphosphate and ADP accelerated Na+,K+-ATPase activity in the presence of 2.7 microM ATP by decreasing the extent of the fluorescence without affecting the amount of phosphoenzyme, irrespective of the modification. These data suggest that Na+,K+-ATPase activity was accelerated due to the acceleration of the breakdown of K+-bound enzyme by high concentrations of ATP and ATP analogues.

Adenosine Diphosphate↗
PubMed1987

The use of permanganate as a sequencing reagent for identification of 5-methylcytosine residues in DNA.

The use of permanganate as a reagent for DNA sequencing by chemical degradation has been studied with respect to its specificity for 5-methylcytosine residues. At weakly acidic pH and room temperature, 0.2 mM potassium permanganate reacts preferentially with thymine, 5-methylcytosine, and to a lesser extent with purine residues, while cytosine remains essentially intact. Permanganate oxidation is, therefore, a suitable DNA sequencing reaction for positive discrimination between 5-methylcytosine and unmethylated cytosine.

5-Methylcytosine↗
PubMed1987

Role of the central dinucleotide at the crossover sites for the selection of quasi sites in DNA inversion mediated by the site-specific Cin recombinase of phage P1.

The crossover sites for Cin-mediated inversion consist of imperfect 12 bp inverted repeats with non-palindromic dinucleotides at the center of symmetry. Inversion is believed to occur in vivo between the homologous central 2 bp crossover sequences at the inversely repeated crossover sites through introduction of 2 bp staggered cuts and subsequent reciprocal strand exchanges. The site-specific Cin recombinase acts not only on the normal crossover sites but also, less efficiently, on quasi crossover sites which have some homology with the normal sites. We identified 15 new quasi sites including 4 sites within the cin structural gene. Homology at the 2 bp crossover sequences between recombining sites favors selection as quasi crossover sites. The Cin enzyme can occasionally mediate inversion between nonidentical crossover sequences and such recombinations often result in localized mutations including base pair substitutions and deletions within the 2 bp crossover sequences. These mutations are explained as the consequences of heteroduplex molecules formed between the staggered dinucleotides and either their subsequent resolution by DNA replication or subsequent mismatch repair. Occasional utilization of quasi crossover sites and localized mutagenesis at the crossover sequences in enzyme-mediated inversion processes would be one of the mechanisms contributing to genetic diversity.

Base Sequence↗
PubMed1987

A transcriptional terminator sequence in the prokaryotic transposable element IS1.

The prokaryotic transposable element IS1 is known to exert a strong polar effect upon integration into an operon. To elucidate this polar effect, we constructed a plasmid which has an IS1 integrated between the 5' half of the tet gene for tetracycline resistance and the cat structural gene for chloramphenicol resistance. The cat gene is expressed by the tet promoter and the presence of IS1 in orientation I, in which the IS1 transposase genes insA and insB are in the same orientation as the cat gene, reduced the cat expression. By introducing deletions or insertions within the IS1 sequence, we were able to map a rho-dependent terminator TIS1A between the insA and insB genes. Translational interruption between these ins genes is important for TIS1A to be an active terminator.

Acetyltransferases↗