Biomedical subjects

K Matsui

Publications and source records attributed to K Matsui.

At least 289 records · Page 16Linked to original sources

PubMed1995

Clinical results of breast-conservation therapy using a CT simulator.

The CT simulator is a real-time, CT-linked, 3-D treatment planning system which consists of a CT scanner, a multi-image display, a treatment planning device with real-time visual optimization, and a laser beam projector. The clinical benefit of this system was evaluated in breast cancer patients undergoing breast-conserving therapy. Between December 1987 and March 1993, 244 breasts in 243 patients underwent breast-conserving therapy at Kyoto University Hospital. Clinically, there were 159 stage I and 85 stage II tumors. Pathological staging showed 216 stage I, 24 stage II, and 4 stage III tumors. All except 10 tumors were invasive ductal carcinomas. Eleven tumors were margin-positive by histopathological examinations. As surgical treatment, quadrantectomy or wide excision with complete axillary dissection was performed. Radiation therapy consisted of 50 Gy delivered to the whole breast by opposed tangential fields over 5 weeks using 60Co gamma rays. For patients with a positive margin, boost electron irradiation was given to a total of 10 Gy. We used the CT simulator for individualized optimization of the tangential fields. Prompt and accurate determination of the tangential portals was possible by using the simulator to determine various parameters, including the beam angle and head rotation angle. During follow-up for 2-66 months (median: 20 months), unrelated death occurred in 2 patients and distant metastases developed in 5 (bone 4, lung 1). However, neither local recurrence nor symptomatic radiation pneumonitis has since occurred. The cumulative survival rate and the disease-free survival rate at five years were 95.2% and 91.8%, respectively. The CT simulator appears to be a useful tool for individualized optimization of tangential irradiation fields in breast-conserving therapy.

Adult↗

PubMed1995

Developmental expression of the nephritogenic antigen of monoclonal antibody 5-1-6.

The biogenesis of p51, the target of nephritogenic monoclonal antibody 5-1-6, was studied in the developing glomerulus by immunolocalization and metabolic labeling. The localization of p51 was compared with that of ZO-1, a component of the cytoplasmic face of the epithelial slit diaphragm, and with that of podocalyxin, and apical marker of the podocyte. p51 first became faintly, but clearly, detectable on the basal and lateral sides of the developing podocytes at the S-shaped body stage. Staining intensity increased with further maturation and was restricted to the visceral epithelial cells. On immunoelectron microscopy, the antigen was seen along the basal and lateral surfaces below occluding junction at the early capillary loop stage and later, with the interdigitation of foot processes, became concentrated in the slit pores. At no stage was p51 seen on the apical surface. p51 and ZO-1 were closely localized in the mature glomerulus but arrived at their final positions from opposite directions. p51 was on basal and podocalyxin was on apical sides of the glomerular epithelium from the S-shaped body stage onwards. Metabolic labeling studies showed that p51 is actively synthesized during initial glomerular development and that the rate of synthesis declines substantially with maturation. We conclude that p51 is primarily synthesized during the initial glomerular development, becomes concentrated in the slit pores of mature podocytes, and serves as a basal differentiation marker for podocytes.

Aging↗

PubMed1995

Mechanisms of the potent and long-lasting antihypertensive action of the new calcium channel blocker pranidipine. Evidence for strong affinity to the calcium channels or membranes.

To elucidate the mechanisms of the potent and long-lasting antihypertensive action of pranidipine (CAS 99522-79-9, OPC-13340), a wash-out experiment in isolated rat aorta preparations and a displacement binding experiment of (+)[3H]PN200-110 (isradipine) with pranidipine and other dihydropyridines to porcine skeletal T-tubules was conducted. It was revealed that the inhibition of KCl-induced contraction by pranidipine remained complete even after washing out the drug 9 times. Also, pranidipine had the lowest Ki value for (+)[3H]PN200-110 binding in skeletal T-tubules. The lipophilicity of pranidipine measured by octanol-buffer partition coefficient was the highest among the tested compounds, and the order of lipophilicity coincided with the order of potency in the displacement binding experiments. These results suggest that pranidipine has a very high affinity to Ca channels or to T-tubule membranes, and strongly support the "membrane-bilayer pathway hypothesis" which assumes the partitioning of the drug into the lipid bilayer before drug binding to Ca channels as an explanation of the potent and long-lasting action of pranidipine compared with other dihydropyridines.

Animals↗

PubMed1995

[Local chemotherapy by a sustained-release preparation with fibrin seal against the operative wound in head and neck cancer].

Fibrin seal has been used for hemostasis and sealing in operative field of tumors in the head and neck. The authors applied it for drug preparation and tried a local chemotherapy to treat residual and disseminated tumors of cellular level in the operative wound using 5-FU. The drug release rate in this therapy in vitro study was 50% after 24 hrs. When injected to rats bearing Yoshida sarcoma, it exhibited a marked antitumor effect compared to the control group given 5-FU alone. This therapy is easy to make the dosage adjustment and can apply drugs directly to the tumor residue at the high concentration. It will be clinically a useful adjuvant therapy for radiotherapy, surgery or chemotherapy.

Animals↗

PubMed1994

Kinetics of T-cell receptor binding to peptide/I-Ek complexes: correlation of the dissociation rate with T-cell responsiveness.

Recognition by T-cell antigen receptors (TCRs) of processed peptides bound to major histocompatibility complex (MHC) molecules is required for the initiation of most T-lymphocyte responses. Despite the availability of soluble forms of TCRs and MHC heterodimers, this interaction has proven difficult to study directly due to the very low affinity. We report here on the kinetics of TCR binding to peptide/MHC complexes in a cell-free system using surface plasmon resonance. The apparent association rates for the interactions of related peptide/MHC complexes to one such TCR are relatively slow (900-3000 M-1.s-1) and dissociation rates are very fast (0.3-0.06 s-1) with t1/2 of 2-12 s at 25 degrees C. The calculated affinity of the engineered soluble molecules compares well with previously reported competition data for native TCRs or competition data reported here for native peptide/MHC complexes, indicating that these soluble heterodimers bind in the same manner as the original molecules expressed on cells. We also find that the peptide variants which give weaker T-cell stimulatory responses have similar affinities but distinctly faster dissociation rates compared with the original peptide (when loaded onto the MHC molecule) and that this later property may be responsible for their lower activity. This has implications for both downstream signaling events and models of TCR-peptide antagonists.

Amino Acid Sequence↗

PubMed1994

Nitrogen-in-the-ring pyranoses and furanoses: structural basis of inhibition of mammalian glycosidases.

Seven pyranoses and three furanoses with a nitrogen in the ring were prepared by chemical synthesis, microbial conversion, and isolation from plants to investigate the contribution of epimerization, deoxygenation, and conformation to the potency of inhibition and specificity of mammalian glycosidases. The seven pyranoses are 1-deoxynojirimycin (1), the D-manno (2), D-allo (3), and D-galacto (4) isomers of 1, fagomine (1,2-dideoxynojirimycin, 5), and the D-allo (6) and D-galacto (7) isomers of 5, while the three furanoses are 2,5-dideoxy-2,5-imino-D-mannitol (8), 1,4-dideoxy-1,4-imino-D-arabinitol (9), and 1,4-dideoxy-1,4-imino-D-ribitol (10). The 2-deoxygenation and/or 3-epimerization of 1 enhanced the potency for rat intestinal lactase and bovine liver cytosolic beta-galactosidase. Especially compound 6 showed a potent inhibitory activity against both enzymes, and compound 8, a mimic of beta-D-fructofuranose, was a potent inhibitor of both beta-galactosidases as well. Compound 4, which has been known as a powerful alpha-galactosidase inhibitor, exhibited no significant inhibitory activity for most of mammalian beta-galactosidases. In addition, compound 6 fairly retained a potency of 1 toward rat intestinal isomaltase. In this study, compound 8, known as a processing alpha-glucosidase I inhibitor in cell culture, has been found to have no effect on processing alpha-glucosidase II, whereas 9 has been shown to be a good nonspecific inhibitor of intestinal isomaltase, processing alpha-glucosidase II, Golgi alpha-mannosidases I and II, and porcine kidney trehalase. It has been speculated that glycosidase inhibitors have structures which resemble those of the respective glycosyl cations. This Broad inhibitory activity of 9 toward various glycosidases suggest that it superimposes well on the various glycosyl cations.

Animals↗

PubMed1994

Developmental changes of nerve growth factor levels in the gracile axonal dystrophy mouse.

Nerve growth factor (NGF) levels were measured in various tissues of the gracile axonal dystrophy (GAD) mouse. When the disease had fully progressed, the NGF levels in the skeletal muscle, dorsal root ganglion and the spinal cord were decreased. These findings suggest that a reduction of the NGF level is involved in the pathophysiological processes in the GAD mouse.

Animals↗

PubMed1994

N-containing sugars from Morus alba and their glycosidase inhibitory activities.

The reexamination of N-containing sugars from the roots of Morus alba by improved purification procedures led to the isolation of eighteen N-containing sugars, including seven that were isolated from the leaves of Morus bombycis. These N-containing sugars are 1-deoxynojirimycin (1), N-methyl-1-deoxynojirimycin (2), fagomine (3), 3-epi-fagomine (4), 1,4-dideoxy-1,4-imino-D-arabinitol (5), 1,4-dideoxy-1,4-imino-D-ribitol (6), calystegin B2 (1 alpha,2 beta,3 alpha,4 beta-tetrahydroxy-nor-tropane, 7), calystegin C1 (1 alpha,2 beta,3 alpha,4 beta,6 alpha-pentahydroxy-nor-tropane, 8), 1,4-dideoxy-1,4-imino-(2-O-beta-D-glucopyranosyl)-D-arabinitol (9), and nine glycosides of 1. These glycosides consist of 2-O- and 6-O-alpha-D-galactopyranosyl-1-deoxynojirimycins (10 and 11, respectively), 2-O-, 3-O- and 4-O-alpha-D-glucopyranosyl-1-deoxynojirimycins (12, 13, and 14, respectively), and 2-O-, 3-O-, 4-O- and 6-O-beta-D-glucopyranosyl-1-deoxynojirimycins (15, 16, 17, and 18, respectively). Compound 4 is a new member of polyhydroxylated piperidine alkaloids, and the isolation of 6 is the first report of its natural occurrence. It has recently been found that the polyhydroxy-nor-tropane alkaloids possess potent glycosidase inhibitory activities. Calystegin A3 is the trihydroxy-nor-tropane, and calystegins B1 and B2 are the tetrahydroxy-nor-tropane. Calystegin C1, a new member of calystegins, is the first naturally occurring pentahydroxy-nor-tropane alkaloid. The inhibitory activities of these compounds were investigated against rat digestive glycosidases and various commercially available glycosidases.

1-Deoxynojirimycin↗

PubMed1994

Enzymic synthesis of alpha- and beta-D-glucosides of 1-deoxynojirimycin and their glycosidase inhibitory activities.

1-Deoxynojirimycin (1) is a potent inhibitor of mammalian and rice alpha-glucosidase. Several glucosides of 1 were synthesized by use of the native and immobilized enzyme and their effect on various enzymes was investigated. Transglucosylation reactions using rice alpha-glucosidase, yeast alpha- and beta-glucosidases purified from Rhodotorula lactosa were performed with maltose or cellobiose as a glucose donor and N-(benzyloxycarbonyl)-1-deoxynojirimycin (2) as an acceptor. The transglucosylation reaction using native rice alpha-glucosidase afforded 3-O-alpha-D-glucopyranosyl-N-(benzyloxycarbonyl)-1-deoxynojirimycin (4), 4-O-alpha-D-glucopyranosyl-N-(benzyloxycarbonyl)-1-deoxynojirimycin (5), and 2-O-alpha-D-glucopyranosyl-N-(benzyloxycarbonyl)-1-deoxynojirimycin (3) in yields of 40, 13, and 2%, respectively, after 30 min. The transglucosylation reaction using immobilized rice alpha-glucosidase was similar to that using the native enzyme. In the system using native yeast alpha-glucosidase, 3, 5, and 4 were formed in yields of 34, 13, and 6%, respectively, after 15 h. The immobilization of yeast alpha-glucosidase caused a significant decrease in transglucosylation activity. Yeast beta-glucosidase showed a high transglucosylation activity and incubation with the reaction system afforded 2-O-beta-D-glucopyranosyl-N-(benzyloxycarbonyl)-1-deoxynojirimycin (6) and 4-O-beta-D-glucopyranosyl-N-(benzyloxycarbonyl)-1-deoxynojirimycin (7) in yields of 69 and 3%, respectively, after 3 h. The transglucosylation reaction using immobilized yeast beta-glucosidase preferentially afforded 6 in a yield of 73% after 3 h. After removal of N-benzyloxycarbonyl group from the product glucosides, their glycosidase inhibitory activities were measured. 3-O-alpha-D-Glucopyranosyl-1-deoxynojirimycin (9) retained the potent inhibition of 1 against rat intestinal sucrase activity and was more effective than 1 against rice alpha-glucosidase. 4-O-alpha-D-Glucopyranosyl-1-deoxynojirimycin (10) retained the potency of 1 against rat intestinal sucrase and isomaltase. 2-O-alpha-D-Glucopyranosyl-1-deoxynojirimycin (8) was more effective than 1 against trehalases.

1-Deoxynojirimycin↗

PubMed1994

Ataxia-ameliorating effects of YM-14673, a potent analog of thyrotropin releasing hormone, in ataxic mutant mice.

The effects of YM-14673 (N alpha-[[(S)-4-oxo-2-azetidinyl]carbonyl]- L-histidyl-L-prolinamide dihydrate), a potent analog of thyrotropin releasing hormone (TRH), on the behavior of ataxic mutant mice (staggerer, realer, Purkinje cell degeneration and weaver mice) were investigated in comparison with those of TRH in an open-field apparatus. The fall index, the ratio of the number of falls to the distance moved, was defined as an index for ataxia. YM-14673 reduced the fall index in all types of ataxic mice examined and was more potent than TRH in reeler, staggerer and Purkinje cell degereration mice. YM-14673 may have a beneficial effect on patients with spinocerebellar degeneration.

Animals↗

PubMed1994

Photodynamic therapy and/or external beam radiation therapy for roentgenologically occult lung cancer.

BACKGROUND AND METHODS: Thirty-nine roentgenologically occult lung cancers in 29 patients were treated using photodynamic therapy (PDT) and/or thoracic radiotherapy (TRT) from January 1986 to March 1992. With the exception of one mixed-tumor case, all were squamous cell carcinomas. RESULTS: Initial PDT achieved complete responses in 25 of 39 (64%) of the cancers. Of the remaining 14 cancers that showed less than complete response (CR), 10 of the 14 (71.4%) showed a CR when subsequently treated with TRT, yielding an overall CR rate of 89.7% for cancers treated. Although nine patients experienced recurrences, six of these had CR when treated with PDT and/or TRT. To date, 22 patients are alive. Causes of death in the patients enrolled in this study are as follows: pyothorax (2); heart failure due to pulmonary hypertension (1); chronic respiratory insufficiency (1); subsequent primary brain cancer (1); and subsequent primary lung cancer (1). Only one died of primary lung cancer. CONCLUSIONS: These findings suggest that PDT and/or TRT may be used as an alternative to surgery in the treatment of selected patients with roentgenologically occult lung cancer.

Adult↗

PubMed1994

Cerebellar nitric oxide synthase, cGMP and motor function in two lines of cerebellar mutant mice, Staggerer and Wriggle Mouse Sagami.

We investigated the hypothesis that nitric oxide (NO) is involved in the cerebellar motor function, by measuring nitric oxide synthase (NOS) activities and cGMP in the cerebellum using two lines of mutant mice having motor dysfunction, Staggerer (SG) and Wriggle Mouse Sagami (WMS). In SG, the NOS activity per cerebellum was reduced to 5.8% of that of the controls, while no significant change was observed in WMS. The cerebellar cGMP in SG was reduced to 3.3% of that of the controls and to 43% in WMS. In contrast with these neurochemical markers of NO, the locomotor dysfunction and the number of falls were greater in WMS than in SG. The reductions of the neurochemical markers of NO are consistent with the results of the previous neuropathological studies in SG and WMS whereas the cerebellar motor dysfunction was independent of these neurochemical and neuropathological changes.

Amino Acid Oxidoreductases↗

PubMed1994

Sugars with nitrogen in the ring isolated from the leaves of Morus bombycis.

It is known that 1-deoxynojirimycin (1) is contained in the leaves and roots of Morus sp. The modified purification procedures of 1 from leaves of Morus bombycis led to the isolation of many polyhydroxylated alkaloids. These include 1, N-methyl-1-deoxynojirimycin (2), 2-O-alpha-D-galactopyranosyl-1-deoxynojirimycin (3), fagomine (4), 1,4-dideoxy-1,4-imino-D-arabinitol (5), 1,4-dideoxy-1,4-imino-(2-O-beta-D-glucopyranosyl)-D-arabinitol (6), and 1 alpha,2 beta,3 alpha,4 beta-tetrahydroxy-nor-tropane (7), designated nortropanoline. The isolation of 2 is the first report of its natural occurrence. Compounds 3 and 6 are the first naturally occurring glycosides of 1 and 5, respectively. Natural alkaloidal glycosidase inhibitors are classified into five structural types: namely polyhydroxylated piperidines, pyrrolidines, pyrrolines, indolizidines, and pyrrolizidines. Nortropanoline is a novel tropane alkaloid and a new type of polyhydroxylated alkaloid.

1-Deoxynojirimycin↗

PubMed1994

Oxygen radical-induced inhibition of alkaline phosphatase activity in reconstituted membranes.

The effects of lipid peroxidation on membrane-bound enzyme activity were examined using reconstituted membranes consisting of intestinal alkaline phosphatase (ALP) and phosphatidylcholine (PC) or dipalmitoylphosphatidylcholine (DPPC). When the PC-reconstituted membranes were incubated with ascorbic acid/Fe2+, the ALP activity decreased with increases in the thiobarbituric acid-reactive substances and conjugated diene values in a time-dependent manner. The kinetic studies on the ALP activity with varying the p-nitrophenyl phosphate or beta-glycerophosphate concentrations showed that the inhibition of the enzyme activity by treatment with these oxidizing agents is mainly due to a decrease in the Vmax value rather than a change in the Km value. The results with several antioxidants suggested that ascorbic acid/Fe(2+)-induced inhibition of the ALP activity is related to generation of .OH radicals. Modification of the reconstituted membranes with malondialdehyde, trans-2-nonenal, or n-heptaldehyde did not affect the ALP activity, suggesting that the secondary degraded products of lipid hydroperoxides had no influence on the enzyme activity. Increasing bityrosine production in the membrane constituents was observed by ascorbic acid/Fe2+ treatment, depending on the incubation time. This finding suggests the possibility that amino acid modifications in the protein molecule are induced by the treatment. Furthermore, the contribution of the lipid organization in ascorbic acid/Fe(2+)-induced inhibition of the ALP activity in the reconstituted membranes was examined by measurements of the fluorescence anisotropy of diphenylhexatriene-labeled membranes. In addition, it was found that the ALP activity in DPPC-reconstituted membranes was also inhibited by treatment with ascorbic acid/Fe2+, similar to the case in PC-reconstituted ones. On the basis of these results, a possible mechanism of ascorbic acid/Fe(2+)-induced inhibition of membrane-bound ALP activity is discussed.

Alkaline Phosphatase↗

PubMed1994

Molecular basis for subtypic differences of the "a" subunit of coagulation factor XIII with description of the genesis of the subtypes.

The "a" subunit of human coagulation factor XIII (F13A) exhibits genetic polymorphism defined by four common alleles, F13A*1A, *1B, *2A, and *2B. We have previously suggested on the basis of the isoelectric focusing patterns of the four allele products that point mutations at two separate sites and one intragenic crossing over might be involved in the genes of F13A polymorphism. Here, we report nucleotide substitutions associated with F13A polymorphism. A C/T transition of the second nucleotide of codon 564 in exon 12 is responsible for the difference between F13A*1A and *1B and that between F13A*2A and *2B, and a set of two base changes in codons 650 and 651 in exon 14 leads to the differences between F13A*1A and *2A and those between F13A*1B and *2B. The four combinations of the point mutations at the two exons thus correspond to the four alleles, two of which were generated by the point mutations from ancestral monomorphic gene. The results suggest strongly that intragenic crossing over must be involved in the genesis of the fourth allele. Polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) methods discriminating these base changes in exons 12 and 14 are also presented.

Alleles↗

PubMed1994

Combined oral administration of etoposide and arabinofuranosylcytosine-5'-stearylphosphate enhances the antitumor effect against P388 ascites tumors.

We investigated the antitumor effect of oral administration of etoposide and arabinofuranosylcytosine-5'-stearylphosphate (C18PCA) against P388 ascites tumors in B6D2F1 mice. Etoposide (25 mg/kg) and C18PCA (5 mg/kg) were given orally on days 1-5 after tumor inoculation. The median life span of the mice treated with etoposide or C18PCA alone was 19.5 and 18 days, respectively. The combination of both drugs significantly extended the median life span to 33 days. To clarify this enhancement of the increase in median life span, we examined intracellular deoxyribonucleoside triphosphate (dNTP) pools, cell-cycle distribution, DNA fragmentation, and the time course of the plasma drug concentration. Etoposide had no effect on intracellular dNTP pools in this experimental system, whereas treatment of cells with C18PCA or with the combination of both drugs resulted in a significant increase in dTTP pools to values ranging from 1.8- to 2.0-fold higher than the control levels. There was a significant increase in cells in the S + G2/M phase when cells had been treated with both etoposide and C18PCA. Agarose-gel electrophoresis of the extracted DNA revealed that C18PCA enhanced the fragmentation of DNA, with a length of about 180 bp being induced by etoposide. The plasma peak levels of etoposide (1000 nM) and ara-C (50 nM) were observed at 20 and 30 min after the simultaneous administration of both drugs, respectively. The plasma etoposide level gradually decreased to 10% of the peak level at 240 min after administration. On the other hand, the plasma concentration of ara-C was maintained at above 20 nM at 240 min. These observations suggest that C18PCA and etoposide act on P388 murine leukemic cells by accumulating cells in the S + G2/M phase. Even if the plasma concentration of ara-C is low, the repair of DNA damage by etoposide may be hindered in the presence of ara-C following an increase in DNA fragmentation.

Administration, Oral↗

PubMed1994

Differential regulation of cation transport of vascular smooth muscle cells in a high glucose concentration milieu.

To gain new insights into the pathogenesis of diabetic angiopathy, the influence of high glucose concentration on cation transport of vascular smooth muscle cell (VSMC) membrane was investigated by measuring Na, K and Ca transport in serially passaged cultured VSMC. (1) Na-K pump activity, described as ouabain sensitive 86Rb uptake, and Na-K cotransport, described as bumetanide sensitive 86Rb washout of VSMC, grown in high glucose concentration medium (460 mg/dl), was lower than that grown in normal glucose concentration medium (100 mg/dl). A smaller 5-N,N-hexamethylene amiloride (HMA) sensitive 22Na uptake (Na-H antiport) in high glucose concentration medium. accounted for this difference. (2) 45Ca uptake was also smaller in VSMC cultured in high glucose concentration medium. However, the washout rate constant for 45Ca was comparable between high and normal glucose cultured VSMC. (3) Both intracellular concentration of Na and cytosolic free Ca concentration concentration ([Ca]i) of high glucose cultured VSMC were greater than normal glucose cultured VSMC. (4) Intracellular water volume based on the equilibrium distribution of 3-O-methyl-[14C]glucose was not different between normal and high glucose cultured VSMC. It is concluded that VSMC grown in high glucose concentration milieu manifests a decreased Na-K, and Ca transport in conjunction with an increase in intracellular concentration of Na and [Ca]i. These results suggest that high glucose, per se, may alter membrane permeability to cations, possibly leading to changes in VSMC contractility and/or proliferation. This abnormality seen in the diabetic state may closely link to the pathogenesis of diabetic angiopathy, thus as a result risking hypertension and vascular disease.

Amiloride↗

PubMed1994

Changes in SH reactivity of the protein in porcine intestinal brush-border membranes associated with lipid peroxidation.

The effects of lipid peroxidation on the SH reactivity of the proteins in porcine intestinal brush-border membranes were examined using a fluorogenic thiol reagent, N-[7-dimethyl-amino-4-methylcoumarinyl]maleimide (DACM) in relation to lipid organization. Changes in the lipid organization were assessed by measurement of the rate of incorporation of 1,6-diphenyl-1,3,5-hexatriene (DPH) into the membrane lipids and the fluorescence anisotropy of DPH-labeled membranes. Treatment of the membranes with an oxygen-radical-generating system, i.e., ascorbic acid/Fe2+/tert-butyl hydroperoxide (t-BuOOH), resulted in decrease in the rate of DACM incorporation into the SH groups of the membrane proteins (DACM-labeling) and the amount of DACM labeled to the SH groups with a decrease in the lipid fluidity, depending on the formation of thiobarbituric acid-reactive substances and conjugated diene. Pretreatment of the membranes with diphenylamine effectively prevented the ascorbic acid/Fe2+/t-BuOOH-induced decreases in the DACM-labeling and DPH incorporation rates, whereas neither superoxide dismutase, catalase, sodium benzoate, nor mannitol showed a protective effect. The contribution of the lipid fluidity to the SH reactivity to DACM of the proteins in the membranes with different levels of lipid peroxidation was further examined using a lipid fluidizer, benzyl alcohol. The results showed that the DPH incorporation rate increased in proportion to increasing concentrations of the alcohol regardless of the peroxidation level of the membranes, whereas the susceptibility of the SH reactivity of the membrane proteins as to benzyl alcohol transitionally changed as the membranes were peroxidized to levels greater than 400 nmol conjugated diene/mg protein.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗