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Biomedical subjects

S Kawata

Publications and source records attributed to S Kawata.

At least 163 records · Page 9Linked to original sources
PubMed1989

Component analysis of spatial and spectral patterns in multispectral images. II. Entropy minimization.

In Part I [J. Opt. Soc. Am. A 4, 2101 (1987)] of this series, we developed a method for estimating both spatial patterns and spectral curves of components in a multispectral scene. This method does not need spatial and spectral information about the components but only multispread imagery data. The estimation is given as a feasible solution set satisfying the nonnegativity constraint for density and spectral response for all components at all pixels. In this paper, we estimate unique solutions for both the component patterns and the spectra from the feasible solution set. The solution is given by optimizing an entropy minimization criterion. This criterion enhances the spectral or spatial features of individual components. Two experimental results are shown to demonstrate the effectiveness of this method with biological and cytochemical specimens. The limitations of this method for unique pattern estimation are also discussed.

Algorithms↗
PubMed1988

Localization of cytochrome P-450 in the colonic mucosa of 3-methylcholanthrene-pretreated and untreated rats. An immunohistochemical study.

Immunohistochemical localization of cytochrome P-450 in the colonic mucosa of 3-methylcholanthrene-pretreated and untreated rats was studied by indirect fluorescent antibody staining technique. A polyclonal antibody for cytochrome P-450MC purified from hepatic microsomes of 3-methylcholanthrene-pretreated rats was used for this experiment. A strong immunofluorescence was found to be localized in the cytoplasm of the surface epithelium of the mucosa in the colon of 3-methylcholanthrene-pretreated rats. A faint immunofluorescence was also observed in the epithelium of untreated rats. 7-Ethoxycoumarin O-deethylase activity of colonic microsomes was significantly enhanced by 3-methylcholanthrene-pretreatment in parallel with an increase in the intensity of immunostaining for cytochrome P-450MC in Western blotting analysis. This is the first report on the localization of cytochrome P-450 in the colonic mucosa.

7-Alkoxycoumarin O-Dealkylase↗
PubMed1988

Transcatheter arterial chemo-embolization for humoral hypercalcemia of hepatocellular carcinoma.

A 50-year-old male with unresectable hepatocellular carcinoma (HCC) had a hypercalcemic crisis with a serum calcium concentration of 7.8 mEq/zeta, without any evidence for bone metastases or parathyroid lesions. The hypercalcemia was thought to be due to increased renal reabsorption of calcium and increased bone resorption, which was probably caused by humoral factors derived from the HCC, some being parathyroid hormone-like factors. Since conservative therapy for hypercalcemia was not sufficiently effective and was accompanied by progressive exacerbation of ascites and leg edema, transcatheter arterial chemo-embolization (TACE) was performed. On the following day, serum calcium concentration decreased from 6.3 mEq/zeta to the normal range, although serum alpha-fetoprotein levels decreased only slightly. Thereafter hypercalcemia did not develop for about 4 weeks. The results demonstrated that TACE can be effective for humoral hypercalcemia of HCC.

Carcinoma, Hepatocellular↗
PubMed1988

The inhibitory effect of forskolin on antibody-dependent cell-mediated cytotoxicity using Chang liver cells as target cells.

The effect of forskolin, a unique adenylate cyclase activator, on antibody-dependent cell-mediated cytotoxicity (ADCC) was examined. ADCC was assayed using Chang liver cells as the target cells, immuned rabbit serum as the antibody and healthy human peripheral blood mononuclear cells (PBMNC) as the effector cells. Forskolin at concentrations ranging from 1 to 20 microM significantly inhibited ADCC in a dose-dependent manner. By the addition of forskolin, cyclic AMP levels did not change in Chang liver cells but increased in PBMNC. Therefore, it appears that forskolin exerted an inhibitory effect on ADCC by increasing the intracellular cyclic AMP levels in PBMNC, the effector cells.

Antibody-Dependent Cell Cytotoxicity↗
PubMed1988

Changes in hepatic functional reserve after transcatheter embolization of hepatocellular carcinoma. Assessment by maximal removal rate of indocyanine green.

To clarify the influence of transcatheter arterial embolization (TAE) on hepatic function, the maximal removal rate of indocyanine green (ICG-Rmax), which represents the hepatic functional reserve, and the plasma disappearance rate of indocyanine green (k-ICG) were measured serially before and after 15 TAE procedures performed on 13 hepatocellular carcinoma (HCC) patients with underlying hepatic diseases. Compared to the values before TAE, ICG-Rmax values did not change or gradually decreased during 4 weeks in seven of the 13 patients but markedly decreased in the remaining six by as much as 50% during the first week. k-ICG values remained almost unchanged at any time after TAE. Albumin and prothrombin time were serially measured before and after 24 TAE procedures performed on 21 HCC patients with underlying hepatic diseases in whom no plasma products had been used for therapy. Albumin decreased by up to 75% in one of the 21 patients during the first week but did not change or gradually decreased in 20 of the 21 patients. Prothrombin time showed no obvious changes. This study showed that prominent changes occurred in ICG-Rmax, i.e., in the hepatic functional reserve, after TAE.

Aged↗
PubMed1987

Modulation of the reductive metabolism of halothane by microsomal cytochrome b5 in rat liver.

To study the modulation of the reductive metabolism of halothane (2-bromo-2-chloro-1,1,1-trifluoroethane) by microsomal cytochrome b5, formation of 2-chloro-1,1,1-trifluoroethane (CTE) and 2-chloro-1,1-difluoroethylene (CDE), major reduced metabolites of halothane, was analyzed in vivo and in vitro. Rats were pretreated with both malotilate (diisopropyl-1,3-dithiol-2-ylidenemalonate) and sodium phenobarbital (malotilate-treated rats) or only with sodium phenobarbital (control rats). The microsomes of malotilate-treated rats had significantly more cytochrome b5 than the controls, whereas the cytochrome P-450 content was not different between the two groups. At the end of 2-h exposure to 1% halothane in 14% oxygen, the ratio of CDE to CTE in arterial blood was significantly higher in malotilate-treated rats than in the controls. Under anaerobic conditions, the formation of CDE and the ratio of CDE to CTE were significantly greater in microsomal preparations of malotilate-treated rats than those of the controls. In a reconstituted system containing cytochrome P-450PB purified from rabbit liver, addition of cytochrome b5 to the system enhanced the formation of CDE and increased the ratio of CDE to CTE. These results suggested that cytochrome b5 enhances the formation ratio of CDE to CTE by stimulating the supply of a second electron to cytochrome P-450, which might reduce radical reactions in the reductive metabolism of halothane.

Anaerobiosis↗
PubMed1987

Induction of delayed-type hypersensitivity by the T cell line specific to bacterial peptidoglycans.

A T cell line specific for the chemically well-defined peptidoglycan of bacterial cell wall, disaccharide tetrapeptide, was established from Lewis rats immunized with the antigen covalently linked to the autologous rat serum albumin. The antigen specificity was examined with various analogues or derivatives of the peptidoglycan. The cell line was reactive to analogues with the COOH-terminal D-amino acid, but least reactive to those with L-amino acid as COOH terminus. Transferring of the T cell line into X-irradiated normal Lewis rats induced delayed-type hypersensitivity in an antigen specific manner.

Animals↗
PubMed1987

Membrane lipid changes in erythrocytes, liver and kidney in acute and chronic experimental liver disease in rats.

Lipid molecules in lipoprotein surfaces exchange with their counterparts in cell plasma membranes. In human or experimental liver disease, plasma lipoprotein surfaces are enriched in cholesterol and deficient in arachidonate; corresponding alterations occur in membrane lipids of erythrocytes. To determine whether similar changes take place in membranes of nucleated cells, the lipid content of plasma and of erythrocyte, liver and kidney membranes was measured in rats with acute (3-day) galactosamine-induced hepatitis or chronic (3-week) biliary obstruction. In both models of liver injury the cholesterol:phospholipid ratio in plasma and in erythrocytes was significantly increased (P less than 0.001). Although this ratio was also elevated in liver and kidney microsomes, only in liver microsomes of obstructed rats was the increase significant (P less than 0.001). However, the cholesterol:phospholipid ratio of kidney brush-border membranes, was significantly higher in bile-duct-ligated rats; presumably, compensating mechanisms limit cholesterol accumulation in intracellular membranes. Kidney brush-border membranes from obstructed rats were deficient in arachidonate as were plasma and erythrocytes. However, arachidonate levels were unchanged in kidney microsomes; renal delta 6-desaturase, the rate-limiting enzyme in the conversion of linoleic acid to arachidonic acid, was increased by 50% (P less than 0.001) and may have counteracted a reduced supply of exogenous lipoprotein arachidonate. We conclude that in experimental liver disease lipoprotein-induced lipid abnormalities can occur in renal membranes, although compensatory mechanisms may operate; the alterations seen, cholesterol accumulation and arachidonate depletion, would be expected to interfere with sodium transport and prostaglandin production, respectively. Our findings support the hypothesis that lipid abnormalities in kidney membranes contribute to the renal dysfunction which is a frequent complication of human liver disease.

Acute Disease↗
PubMed1987

Topographic estimations by component spectroanalysis of two formazans of nitroblue tetrazolium in tissue sections.

A component-spectroanalysis technique was used to study the multicolor properties of histochemically stained tissue sections. We developed a method that makes it possible to obtain separately both the spectral patterns and spatial distributions of different color components in tissue sections. To illustrate the application of this technique, we examined the extinction spectrum of reduced nitroblue tetrazolium (NBT), which is used for the detection of dehydrogenase activity. Upon the reduction of NBT, mono- and diformazans are formed, and these exhibit over-lapping extinction spectra. When succinate dehydrogenase (SDH) activity in rat liver lobules was examined using NBT, monoformazan was found to be present at higher concentrations than diformazan and to have a uniform distribution, whereas the concentration of diformazan increased with a steep gradient between the center and periphery of lobules. In rat skeletal muscle fibers, diformazan was present at higher concentrations than monoformazan. The level of SDH activity was topographically represented by the hydrogen concentration calculated from the concentrations of the two formazans. This method is effective for separating multiple components such as mono- and diformazans in histochemical reactions.

Animals↗
PubMed1987

Effect of cholestyramine on bile acid metabolism in conventional rats.

Effects of cholestyramine on biliary secretion of cholesterol, phospholipids and bile acids and fecal excretion of sterols and bile acids were examined in Wistar male rats. Six rats were fed a basal diet, and the other six were fed a basal diet supplemented with 5% cholestyramine for eight days. Bile flow and biliary secretion of bile acids and phospholipids (per hour per rat) decreased with cholestyramine treatment, while biliary cholesterol secretion (per hour per rat) remained unchanged. In the biliary bile acid composition, a marked increase of chenodeoxycholic acid with a concomitant decrease of beta-muricholic acid was observed in cholestyramine-treated rats. Fecal excretion of total sterols and bile acids increased about three- and four-fold, respectively, after cholestyramine treatment. The increase of fecal bile acids derived from cholic acid was more predominant than that derived from chenodeoxycholic acid, resulting in an increase of the cholic acid group/chenodeoxycholic acid group ratio.

Animals↗
PubMed1987

Papillary-cystic neoplasm of the pancreas with multiple hepatic metastases: a case report.

We report a case of papillary-cystic neoplasm (PCN) of the pancreas in a 42-yr-old woman. Because of complication with multiple hepatic metastases, the patient could not receive radical operation, and was treated palliatively. The right hepatic tumors decreased in volume by an average of 28% (range: 13-54%) following intra-arterial infusion of doxorubicin and gelatine sponge--i.e. chemoembolization therapy. On the other hand, the left lobe tumor increased by 15% in volume following intra-arterial infusion of doxorubicin alone without selective embolization. A subsequent systemic combination chemotherapy (combinations of 5-fluorouracil, doxorubicin and mitomycin-C) was less effective for both the primary and metastatic sites of PCN of the pancreas. Intra-arterial chemoembolization proved useful--as expected--as a palliative measure. Papillary-cystic neoplasm of the pancreas accompanied by hepatic metastasis is very rare. We present herein its clinical behavior and response to the above treatment as documented by CT scan.

Adult↗
PubMed1987

Hepatic conversion of 1-(tetrahydro-2-furanyl)-5-fluorouracil into 5-fluorouracil in patients with hepatocellular carcinoma.

The pharmacokinetics of 1-(tetrahydro-2-furanyl)-5-fluorouracil (FT) and its conversion into 5-fluorouracil (FUra) in liver tissue were studied in ten patients with hepatocellular carcinoma (HCC). The plasma concentration of FT after its intravenous injection (dosage: 800 mg) was computerfitted to a bi-exponential function (C = Ae-alpha t + Be-beta t), indicating a two-compartment disposition. The pharmacokinetic parameters did not significantly differ between the five patients with, and the five without cirrhosis of the liver. The plasma concentrations of FUra likewise showed no significant difference between the two groups. The rates of FT degradation in the liver tissue homogenate were similar for four of the patients with cirrhosis (0.10 +/- 0.05 mumol/g liver protein/30 min) and four of those without it (0.13 +/- 0.05). The rates of cytochrome P-450-dependent FUra formation in the microsomal fraction of liver tissue from two patients (1.1 and 1.3 nmol/mg microsomal protein/30 min) were dramatically reduced to less than half of those of two control subjects (2.4 and 2.7). The estimated rates of FUra formation in the soluble fraction (105,000 X g supernatant fraction) from the two patients (0.1 and 0.13 nmol/mg protein/30 min) were almost identical to those from the controls (0.12 and 0.14), suggesting that the rate in the soluble fraction from HCC patients may not be as strongly affected as the rate in the microsomal fraction.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1987

Selective reduction of hepatic cytochrome P450 content in patients with intrahepatic cholestasis. A mechanism for impairment of microsomal drug oxidation.

Alteration of the components of the mixed-function oxidase system, including cytochrome P450, cytochrome b5, cytochrome P450 reductase, and cytochrome b5 reductase, was examined in liver microsomes prepared from needle biopsy samples of 12 patients with intrahepatic cholestasis. The rate of p-nitroanisole O-demethylation in the microsomes was also measured as the activity of cytochrome P450-dependent drug oxidation. The cytochrome P450 content (0.29 +/- 0.05 nmol/mg microsomal protein) in the patients was significantly lower than that in the 11 control subjects (0.41 +/- 0.09). The rate of p-nitroanisole O-demethylation was also significantly lower in the patients. However, the cytochrome b5 content and the activities of the reduced forms of nicotinamide adenine dinucleotide phosphate- and nicotinamide adenine dinucleotide-cytochrome c reductases did not differ between the two groups. Thus, selective reduction of cytochrome P450 seems to play a major role in the impairment of microsomal drug oxidation during intrahepatic cholestasis. Moreover, the reduction of cytochrome P450 was correlated with the serum concentrations of total bilirubin and bile acid but not with the serum glutamic oxaloacetic transaminase value. These observations suggest that the reduction of cytochrome P450 might be related to the severity of cholestasis.

Adult↗
PubMed1987

Activation of the human complement cascade by bacterial cell walls, peptidoglycans, water-soluble peptidoglycan components, and synthetic muramylpeptides--studies on active components and structural requirements.

Cell walls isolated from 29 strains of 24 gram-positive bacterial species, whose peptidoglycans belong to the group A type of Schleifer and Kandler's classification, with one exception (Arthrobacter sp.), were shown to activate the complement cascade in pooled fresh human serum mainly through the alternative pathway and partly through the classical one. The complement-activating effect of cell walls (5 species) possessing group B type peptidoglycan, except those of Corynebacterium insidiosum, was weaker than that of the walls with group A type peptidoglycan. Preparations of peptidoglycan isolated from cell walls of Staphylococcus aureus, Streptococcus pyogenes, and Lactobacillus plantarum also activated the alternative pathway of the complement cascade, but less effectively than the respective parent cell walls. A water-soluble "polymer" of peptidoglycan subunits (SEPS), which was prepared from Staphylococcus epidermidis peptidoglycans by treatment with a cross-bridge degrading endopeptidase, retained most of the complement-activating ability of the parent cell walls. A peptidoglycan "monomer," SEPS-M, which was obtained by hydrolysis of the glycan chain of SEPS with endo-N-acetylmuramidase to disaccharide units did not activate complement. In conformity with this finding, neither synthetic N-acetylmuramyl-L-alanyl-D-isoglutamine (MDP) nor MDP-L-Lys-D-Ala activated the complement cascade. Among several lipophilic derivatives of MDP, 6-O-(3-hydroxy-3-docosylhexacosanoyl)-MDP-L-Lys-D-Ala (BH48-MDP-L-Lys-D-Ala) and 6-O-(2-tetradecylhexadecanoyl)-MDP (B30-MDP) were shown to activate complement through the alternative as well as the classical pathway and exclusively through the classical pathway, respectively. The finding that a D-isoasparagine analog of B30-MDP caused the same effect as the parent molecule strongly suggests that the activation of complement by B30-MDP is different from that caused by cell wall peptidoglycans and a water-soluble "polymer" of peptidoglycan subunits.

Acetylmuramyl-Alanyl-Isoglutamine↗
PubMed1987

Structural requirements of muramylpeptides for induction of necrosis at sites primed with Mycobacterium tuberculosis in guinea pigs.

Intracutaneous injection of N-acetylmuramyl-L-alanyl-D-isoglutamine (MDP) in guinea pigs caused an extensive necrotic reaction in footpads prepared by injection of heat-killed Mycobacterium tuberculosis in water-in-mineral-oil emulsion. We examined a variety of analogs and derivatives of muramylpeptides for their ability to provoke this reaction. A maximum and a minimum structure responsible for the necrotic reaction were found to be N-acetylglycosaminyl-beta(1-4)-N-acetylmuramyl-tripeptide (GlcNAc-MurNAc-L-Ala-D-isoGln-meso-A2pm) and MDP, respectively. An unexpected finding was that GlcNAc-MurNAc-tetrapeptides having L-amino acids at their C termini, unlike comparable compounds having C-terminal D-amino acids, exhibited definite necrosis-inducing activity, probably due to their tendency to undergo in vivo degradation to GlcNAc-MurNAc-tripeptide. Introduction of some acyl groups, especially the stearoyl group, to the 6-O position of the muramic acid or the peptide moiety of muramylpeptides increased the necrosis-inducing activity of the parent molecules. However, this was not observed with 1-thio-muramic acid analogs of MDP. Modification of the alpha- or gamma-carboxyl groups of the glutamic acid residues of muramylpeptides tended to decrease their necrosis-inducing ability. Analogs and derivatives of muramylpeptides which are capable of inducing necrosis at a primed site, with few exceptions, exhibited powerful adjuvanticity against ovalbumin in guinea pigs. However, the reverse was not necessarily true.

Acetylmuramyl-Alanyl-Isoglutamine↗
PubMed1987

Component analysis of spatial and spectral patterns in multispectral images. I. Basis.

A new (to our knowledge) theory of component pattern analysis in multispectral images is developed by using the methods of principal component analysis and nonlinear optimization with a nonnegativity constraint. Given images of a scene in different color bands, we estimate both the spectral curves of components included in the image and the spatial pattern corresponding to each spectral curve. In this method, neither spatial nor spectral features of the components are necessary, but the physical rule of nonnegative absorptivity and density nonnegativity is used for any material of any optical frequency at any position in the image. Experimental results of component analysis with real microscopic image data are shown to demonstrate the effectiveness of the proposed method.

Form Perception↗