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Biomedical subjects

S Katoh

Publications and source records attributed to S Katoh.

At least 109 records · Page 6Linked to original sources
PubMed1997

The first skull of Australopithecus boisei.

Australopithecus boisei was first described from a cranium recovered in 1959 from Olduvai Gorge, Tanzania. This and subsequent finds, mostly from Kenya's Turkana basin, resulted in its characterization as a specialized Australopithecus species with a hyper-robust masticatory apparatus. A distinct A. boisei facial morphology has been emphasized to differentiate robust Australopithecus lineages from East and South Africa. A preference for closed and/or wet habitats has been hypothesized. Here we report some new A. boisei specimens, including the taxon's first cranium and associated mandible, from Konso, Ethiopia. These fossils extend the known geographical range of A. boisei. They provide clear evidence for the coexistence of A. boisei and Homo erectus within a predominantly dry grassland environment. The A. boisei specimens from Konso demonstrate considerable morphological variation within the species. The unexpected combination of cranial and facial features of this skull cautions against the excessive taxonomic splitting of early hominids based on morphological detail documented in small and/or geographically restricted samples.

Animals↗
PubMed1997

The rescuing effect of nerve growth factor is the result of up-regulation of bcl-2 in hyperoxia-induced apoptosis of a subclone of pheochromocytoma cells, PC12h.

The rat pheochromocytoma cell line PC12 is useful for studying neuronal cell differentiation since this cell line differentiates into neuron-like cells in response to nerve growth factor (NGF). We demonstrated that PC12h cells, a subclone of PC12 cells, died under hyperoxia (50% O2). This cell death did not occur in the presence of antioxidant reagents. In the dead cells, DNA fragmentation and chromatin condensation were observed, suggesting that hyperoxia-induced apoptosis via reactive oxygen species (ROS). NGF effectively suppressed this hyperoxia-induced apoptosis. Accordingly, the amounts of bcl-2, a proto-oncogene product, increased in the cells rescued from apoptosis by NGF. Furthermore, bcl-2 antisense oligonucleotide canceled this rescuing effect of NGF. The present findings indicate that NGF rescues PC12h cells from hyperoxia-induced apoptosis via up-regulation of bcl-2.

Animals↗
PubMed1997

Solution structure of ferredoxin from the thermophilic cyanobacterium Synechococcus elongatus and its thermostability.

The three-dimensional structure of ferredoxin, purified from the thermophilic cyanobacterium Synechococcus elongatus, was determined in aqueous solution by two-dimensional proton nuclear magnetic resonance. In addition to the 946 distance constraints from nuclear Overhauser effect connectivities, we added 241 distance constraints derived from the crystal structure of Spirulina platensis ferredoxin to the 19 residues close to the [2Fe-2S] iron-sulfur center, where crosspeaks disappeared due to paramagnetic effects. The atomic root-mean-square difference of the ten converged structures from the mean structure was 0.61(+/-0.12) A for backbone atoms (N, C(alpha), C'). The main-chain structure was almost the same as the crystal structures of other mesophile ferredoxins, but comparison of the side-chain structures revealed an extension of the hydrophobic core, a unique hydrophobic patch on the surface of the large beta-sheet, and two unique charge networks in this thermostable ferredoxin structure, some of which might contribute to thermostability.

Amino Acid Sequence↗
PubMed1997

Evaluation of antioxidant activity by chemiluminescence.

A sensitive and simple chemiluminescent method for measuring antioxidant activity was developed. The method is based on antioxidant-dependent quenching of chemiluminescence generated from lipid hydroperoxide and isoluminol/microperoxidase reagent. This method was used to evaluate the antioxidant ability of various antioxidants by measuring the half-inhibition concentration (IC50). The results were compared to those measured with an oxygen electrode method. They were approximately similar in pattern and level, although there was some discrepancy, which was assumed to be due to a possible difference in the reaction mechanisms of the two methods. This method also suggested an additive property of antioxidant activity with different antioxidants. Thus, the present method was used to evaluate the total antioxidant activity in biological tissues such as rat serum, human saliva, and green tea.

Animals↗
PubMed1997

Purification of endothelin from a conditioned medium of cardiac fibroblastic cells using beating rate assay of myocytes cultured in a serum-free medium.

A conditioned medium from cardiac fibroblastic cells stimulated the beating of quiescent cardiac myocytes cultured in a serum-free medium. The aim of this study was to isolate and characterize the myocyte beat-stimulating activity of the conditioned medium of fibroblastic cells. Cardiac myocytes and fibroblastic cells were isolated individually from neonatal rats. The fibroblastic cells were grown in a growth medium until they became confluent, then serum-free conditioned medium was obtained from them. For the beating-rate assay, the cardiac myocytes were cultured in a completely serum-free medium. The beat-stimulating factor of myocytes in the conditioned medium was purified by reverse-phase liquid chromatographies and gel filtration, and was characterized by measuring the molecular weight of the activity and a pharmacological antagonistic study. The beat-stimulating activity in the conditioned medium was purified into two active fractions. Both of the activities have a molecular weight of 2.5 kDa, and the activities were abolished similarly by FR139317, an endothelin type-A receptor antagonist. These results indicate that cardiac fibroblastic cells secrete endothelin and that this may contribute in part to the functional abnormalities of the heart in patients with myocardial fibrosis.

Animals↗
PubMed1997

Functional roles of protein domains on rice alpha-amylase activity.

Characteristics of two rice alpha-amylases Amy1A and Amy3D, and those of two chimeric enzymes Amy1A/3D and Amy3D/1A, engineered from the two isozymes, were compared in the light of the functional roles of protein domains in alpha-amylase. The enzymes that have an Amy1A-type N-terminal domain, Amy1A and Amy1A/3D, showed high activity against soluble starch, while the enzymes that have an Amy3D-type barrel structure, Amy3D and Amy1A/3D, showed high activity in oligosaccharide hydrolysis. Rigidity of protein folding also significantly affected the enzyme activity in both soluble starch and oligosaccharide hydrolysis. Thus, the present work suggests that the structure of the N-terminal domain is important for stability and soluble starch hydrolysis, while the barrel structure that forms the active site significantly affects enzyme activities in oligosaccharide degradation. We have already characterized two rice alpha-amylase isozymes, Amy1A and Amy3D, and a chimeric enzyme engineered from these two isozymes, Amy1A/3D (Terashima et al. 1995, 1996a,b). In spite of the high homology (70%) of their amino acid sequences, Amy1A and Amy3D showed distinct differences in their enzymatic characteristics. The chimeric enzyme Amy1A/3D, which consists of an Amy1A-type N-terminal domain and an Amy3D-type barrel structure, inherited enzymatic characteristics from the both isozymes. In this work, one other chimeric enzyme, Amy3D/1A, which is the counterpart of Amy1A/3D, has been characterized. The characteristics of these four enzymes are discussed in the light of the functional roles of protein domains.

Amylases↗
PubMed1997

Purification of alpha-amylase by specific elution from anti-peptide antibodies.

Chimeric alpha-amylase, produced by recombinant yeast cells, was purified by immunoaffinity chromatography by use of an anti-peptide antibody and an eluent containing an antigen peptide. Chimeric alpha-amylase was adsorbed by the antibody against the peptide corresponding to the C-terminal region of target alpha-amylase, and specifically eluted by the eluent containing the antigen peptide used for immunization. A low concentration of the peptide could competitively elute adsorbed alpha-amylase, and the rate-limiting step of the elution was mass transfer of desorbed alpha-amylase. With this specific method, target proteins can be effectively eluted, and highly purified under mild conditions, from the antibody ligand showing a high-affinity for the adsorption step

Adsorption↗
PubMed1997

Possible implication of leukocytes in secondary pathological changes after spinal cord injury.

We reviewed 95 consecutive patients with cervical spinal cord injury admitted within 2 days of injury and treated nonoperatively, to elucidate the relationship between neurological deterioration and the white blood cell count in the first 4 days after injury. The count for 14 patients who had neurological deterioration was 13.2 +/- 3.2 x 10(9)/l, and that for 81 patients who had no deterioration was 11.0 +/- 3.1 x 10(9)/l. None of 19 patients whose highest white blood cell count was less than 9 x 10(9)l deteriorated, while 14 of 76 patients whose count was 9 x 10(9)/l or more deteriorated. These results suggest that the white blood cell is important in the secondary pathological changes after mechanical injury to the spinal cord.

Adult↗
PubMed1997

Influence of highly purified eicosapentaenoic acid ethyl ester on insulin resistance in the Otsuka Long-Evans Tokushima Fatty rat, a model of spontaneous non-insulin-dependent diabetes mellitus.

We investigated the effect of long-term administration of highly purified eicosapentaenoic acid ethyl ester (EPA-E), an n-3 polyunsaturated fatty acid derived from fish oil, in comparison to the effects of lard, olive oil, safflower oil, or distilled water as the control on the development of insulin resistance in Otsuka Long-Evans Tokushima Fatty (OLETF) rats, a model of spontaneous non-insulin-dependent diabetes mellitus (NIDDM) with obesity. After 17 or 18 weeks of treatment, the glucose infusion rate (GIR) in the euglycemic insulin-glucose clamp test only showed a significant increase in EPA-E-treated rats compared with control rats given distilled water alone as the vehicle. The GIR in EPA-E-treated animals was approximately three times greater than in the controls. This is the first report to display the influence of various fatty acids on the development of insulin resistance in OLETF rats. We demonstrated that EPA-E prevents the onset of insulin resistance, whereas olive oil and safflower oil have no effect and lard exacerbates insulin resistance. Fatty acid analysis of phospholipids in skeletal muscle showed a significant increase of the C18:2, C20:5, and C22:5 components in EPA-E-treated rats and, conversely, a significant decrease in C20:4. In addition, EPA-E-treated rats showed a significant increase in GLUT4 mRNA in skeletal muscle when compared with control rats. Our results indicate that the beneficial effect of EPA-E on insulin resistance in OLETF rats is likely to be dependent on modification of the phospholipid components of the skeletal muscle membrane. These findings suggest that dietary fatty acids may play a key role in the development of insulin resistance in patients with NIDDM.

Animals↗
PubMed1997

The importance of cellular environment to function of the CD44 matrix receptor.

Much has been learned recently by experimental manipulation of the structure of CD44 and assessment of the resulting functions. However, even greater structural variation is naturally introduced by CD44-bearing cells. A structural model is now available for the portion of CD44 that recognizes hyaluronan, but it is clear that all domains of the molecule influence CD44 functions.

Animals↗
PubMed1997

Isolation, properties and a possible function of a water-soluble chlorophyll a/b-protein from brussels sprouts.

A water-soluble Chl a/b-protein (CP673) was isolated and purified from Brussels sprouts (Brassica oleracea L. var. gemmifera DC). The protein had a molecular mass of 78 kDa and an isoelectric point of 4.7, consisted of three or four subunits of 22 kDa and was extremely heat-stable. Although CP673 contained about one Chl a per protein, the blue and red absorption bands of Chl a that consisted of three or four Chl a forms with different absorption maxima suggested that there are several different modes or sites of binding for Chl a. Chl a/b ratio of larger than 10 also indicated that Chl b is present only in a small fraction of CP673. The heterogeneity of CP673 in terms of composition and binding of Chl suggests that Chl is not an intrinsic component of the Chl-protein. Homology search showed that the N-terminal amino acid sequence of CP673 is highly homologous with that of a 22 kDa protein that accumulates in water-stressed leaves of two Brassicaceae plants, rapeseed and radish, but not with those of the light-harvesting Chl a/b-proteins of photosynthesis. A possible function of the water-soluble Chl-protein was discussed.

Amino Acid Sequence↗
PubMed1997

Usefulness of a nonmachinery based system for the reinfusion of cell-free and concentrated autogenous ascitic fluid.

A nonmachinery based system using gravity dependent flow for the treatment and reinfusion of ascitic fluid was developed, and its usefulness was assessed. In a preliminary study using bovine plasma, samples with protein concentrations below 5.0 g/dl were found to be treatable with this system. Bovine plasma containing blood, prepared to 0.5% hematocrit and with a protein concentration of 3.0 g/dl, was also treatable. We conducted a clinical study of 1,799 treatment sessions (1,495 using a machinery based system and 304 using a nonmachinery based system) of 343 patients with ascites refractory to various treatments. The recovery ratio of protein from the original ascitic fluid was 96% using the nonmachinery based system and 77% with the machinery based system (p < 0.01). Of 253 continuous reinfusions of ascitic fluid using the nonmachinery based system, the original ascitic fluid at protein concentrations below 2.5 g/dl was treatable. Original ascitic fluid below a hematocrit of 0.7% (protein concentration, 1.4 g/dl) was also treatable. This new procedure was simple and time and labor saving; the high recovery ratio of protein also demonstrated the usefulness of the new system.

Adult↗
PubMed1997

[Angle of defect on 123I-MIBG myocardial SPECT].

The quantitative assessment of infero-posterior defect on 123I-metaiodobenzylguanidine (MIBG) myocardial scintigraphy was studied in 150 patients with non-ischemic heart diseases at rest. The bull's eye map, obtained from the SPECT images at 4 hours after MIBG injection, was evaluated by generating the blacked out map which exhibits regions with reduced % uptake under mean-2 SD of 13 normal controls. The blacked out regions involved infero-posterior segments and were closely resembled to the sector form. The central angle of this sector, which was named as angle of defect (AOD), significantly correlated with both the heart-to-mediastinum activity ratio (H/M) and the myocardial clearance of MIBG. Because H/M and clearance are widely used as quantitative indices in MIBG myocardial scintigraphy, these results indicate that AOD can also be used as a quantitative index of abnormal cardiac sympathetic nervous function, which is likely to appear in infero-posterior regions in non-ischemic cardiac diseases.

3-Iodobenzylguanidine↗
PubMed1997

[Evaluation of 123I-MIBG clearance from the myocardium; comparison of two methods--SPECT & planar methods].

In 123I-metaiodobenzylguanidine (MIBG) scintigram, MIBG clearance from the heart is used to evaluate the severity of various heart diseases. There are two methods for calculating MIBG clearance. One involves planar images (planar method) and the other uses a bull's eye map (SPECT method). In 158 patients and 10 normal subjects, we compared these two methods. Fifteen minutes and 4 hours after intravenous injection of 111 MBq MIBG, planar images and SPECT images were obtained. Then clearance from the heart was calculated by each method. Abnormal increase was defined as present if clearance was more than the mean + standard deviation of 10 normal subjects. Then, we examined the sensitivity with which each method could detect clearance abnormality in 158 patients. Thirty-two patients showed abnormality only on SPECT images, while planar images alone showed abnormalities in only 5 patients. The reason the SPECT method was more sensitive than the planar method may be as follows; in the case of decreased MIBG clearance from the lung, for example, in congestive heart failure, clearance by planar method is apparently decreased. Thus, the SPECT method can detect clearance abnormality more sensitively than the planar method, and if we evaluate MIBG clearance from the heart by the planar method, we must take into account MIBG clearance from the lung.

3-Iodobenzylguanidine↗
PubMed1996

Nerve growth factor rescues PC12 cells from apoptosis by increasing amount of bcl-2.

Nerve growth factor (NGF) suppressed the decrease in number of viable PC12 cells after serum withdrawal from culture medium. Accordingly, the amount of bcl-2, a suppressive effector of apoptosis, increased in these cells. Bcl-2 antisense oligonucleotide suppressed not only the NGF-induced increase in bcl-2 but also NGF-induced neuronal differentiation. Results of fluorescent DNA staining indicated that NGF inhibited the chromatin condensation of PC12 cells resulting from serum withdrawal and further that the bcl-2 antisense oligonucleotide canceled this effect of NGF. The present results suggest that NGF rescues PC12 cells from apoptosis induced by serum withdrawal via up-regulation of bcl-2.

Animals↗
PubMed1996

Secondary structure and thermostability of the photosystem II manganese-stabilizing protein of the thermophilic cyanobacterium Synechococcus elongatus.

The secondary structure of the manganese-stabilizing protein of the thermophilic cyanobacterium Synechococcus elongatus in solution was investigated by Fourier-transform infrared (FT-IR) and circular dichroism (CD) spectroscopies. Both methods showed a high proportion of disordered structure (40-43%) and a relatively small amount of beta-sheet (23-24%) and alpha-helix (17-19%). The conformation of the protein remained essentially unchanged at temperatures up to 70 degrees C. Unfolding of the protein occurred at higher temperatures and FT-IR spectroscopy revealed that beta-sheet was more strongly unfolded than alpha-helix at 76 degrees C. The protein largely lost the ordered secondary structures at 90 degrees C, but, when cooled down to 30 degrees C, regained its original conformation. Thus, the cyanobacterial protein is very thermostable and its denaturation at an extremely high temperature is reversible.

Bacterial Proteins↗