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Biomedical subjects

I Kato

Publications and source records attributed to I Kato.

At least 415 records · Page 23Linked to original sources
PubMed1991

Insulin binds to type V collagen with retention of mitogenic activity.

The abilities of eight extracellular matrix proteins, fibronectin, vitronectin, laminin, and collagen types I, II, III, IV, and V to bind insulin were examined by binding studies with insulin conjugated with peroxidase. At a physiological pH and ionic strength, type V collagen bound to insulin most strongly. The other types of collagen, laminin, and vitronectin also bound insulin with affinity lower than that of type V collagen. The insulin-binding site of type V collagen was in a 30-kDa CNBr fragment of the alpha 1 (V) chain. Analysis of the amino acid sequence showed that this 30-kDa fragment was identical to the heparin-binding fragment of type V collagen. The insulin-binding sites of laminin and vitronectin were located in the A chain and in the heparin-binding domain, respectively. Insulin bound to type V collagen stimulated the synthesis of DNA by mouse mammary tumor MTD cells, indicating that bound insulin retained mitogenic activity.

Amino Acid Sequence↗
PubMed1991

Detection of Mycoplasma hyopneumoniae DNA by the polymerase chain reaction.

DNA amplification by the polymerase chain reaction (PCR) was examined to detect DNA of Mycoplasma hyopneumoniae, an etiological agent of porcine pneumonia. A pair of synthetic primers was selected that specify the amplification of a 520-basepair DNA fragment in a reiterative sequence of M. hyopneumoniae genome. The PCR product was detected by direct gel electrophoresis or by blot hybridization to a synthetic oligonucleotide probe. The specificity of PCR for M. hyopneumoniae was confirmed by lack of cross-reactivity to DNA from other porcine mycoplasmas.

Base Sequence↗
PubMed1991

Direct measurement of calpastatin subtypes by sandwich enzyme immunoassay using monoclonal antibodies.

Six stable hybridoma cell lines secreting monoclonal antibodies to human calpastatin were established. All monoclonal antibodies belong to the IgG1 subclass and recognized different epitopes on calpastatin. At least two groups were distinguished; the first group was specific for muscle-type (M-) calpastatin and the second group recognized not only M-calpastatin but also erythrocyte-type (E-) calpastatin. The inhibitory effect of all monoclonal antibodies on calpastatin activity was relatively low even at high concentrations of antibodies. Enzyme immunoassay systems were developed for direct determination of calpastatin subtypes in human cells requiring no other sample treatment than the disruption of the cells. The assay methods were, in principle, based on the sandwich enzyme immunoassay using epitope-specific monoclonal antibodies. The enzyme immunoassay system for M-calpastatin was specific for M-calpastatin and could not detect E-calpastatin. The enzyme immunoassay system for total calpastatin detected not only M-calpastatin but also E-calpastatin. The sensitivity of these assay systems was 10 pmol l-1 of calpastatins. Antigenicity of calpastatins was found to be unchanged in the presence of EDTA and haemoglobin. Good reproducibilities of within-and between-assay series and excellent recovery of exogenous calpastatins from cell lysates were observed. From these results, it seems that our newly developed subtype-specific enzyme immunoassay systems for calpastatins are useful in biochemical studies and clinical testing for determination of calpastatin subtypes.

Antibodies, Monoclonal↗
PubMed1991

Production and characterization of functional domains of human fibronectin expressed in Escherichia coli.

An efficient expression system was constructed in Escherichia coli that produced a 33-kDa fragment, C-274, of human fibronectin with a strong cell-adhesive activity. The entire sequence of the heparin-binding domain with 271 amino acids, H-271, was also expressed. Deletion analysis of the type III repeats showed that the heparin-binding site was at type III-13. The cell-adhesive activity of a fusion protein, CH-271, containing the cell- and the heparin-binding domains was twice that of C-274 when BHK but not B16-F10 melanoma cells were tested; H-271 alone was inactive. Recombinant proteins containing the CS1 sequence of the IIICS region were more active than C-274 and CH-271 with B16-F10. However, H-296, which contained both H-271 and CS1, was almost inactive with BHK. CH-296, which contained CS1 at the C-terminus of CH-271, was more active with B16-F10 than H-296 and C-CS1, which was produced by the deletion of H-271 from CH-296. Thus, the cell-binding domain was active with both kinds of cells. The heparin-binding domain promoted the adhesion of both kinds of cells only when linked to the cell-binding domain or CS1. CS1 was specific for the adhesion of B16-F10 but was not essential.

Animals↗
PubMed1991

Simultaneous detection and typing of genital human papillomavirus DNA using the polymerase chain reaction.

A simple method has been developed for detecting a broad range of genital human papillomavirus (HPV) types using the polymerase chain reaction (PCR). We utilized two consensus sequence primer pairs within the E6 and E7 open reading frames to amplify HPV DNA; malignant HPV DNA (from HPV-16, -18, -31, -33, -52b and -58) was amplified using the pU-1M/pU-2R primer pair whereas benign HPV DNA (from HPV-6 and -11) was amplified using the pU-31B/pU-2R primer pair. Identification of the amplification product was confirmed by restriction enzyme digestion. In this study, a pU-1M/pU-2R-mediated PCR was successfully applied to 39 cervical carcinoma specimens; HPV-16 was detected in 19 cases, HPV-18 in five cases, HPV-31 in two cases, HPV-33 in two cases, HPV-52b in one case, HPV-58 in three cases, and an unknown type(s) was detected in four cases. Overall, the prevalence of HPV was 84.6%. The results indicate that this detection system is useful for the detection of HPVs not only of known types but also of new types.

Base Sequence↗
PubMed1991

Bacterial ADP-ribosylating toxins: molecular structures and signal transducing functions.

Mono-ADP-ribosylation is a posttranslational modification of proteins employed by a variety of bacterial ADP-ribosylating toxins to modify the metabolism of target cells. The ADP-ribosyltransferases of bacterial toxins, in general, use NAD as a substrate for covalent modification by ADP-ribose to certain GTP-binding proteins (G proteins) as signal transducers resulting in altered enzymatic activity of the membrane enzymes as effectors. Such a mechanism has the potential of being of importance in the physiological regulation of cellular metabolism, particularly if the process is reversible. These ADP-ribosylating toxins are characterized in Table 1.

ADP Ribose Transferases↗
PubMed1991

Inhibitory effect of fibronectin and its recombinant polypeptides on the adhesion of metastatic melanoma cells to laminin.

We have utilized recombinant fibronectin fragments with cell-binding domain (C-274), heparin-binding domain (H-271) or CS1 peptide in type III connecting segment (IIICS) and their fusion polypeptides such as CH-296 (containing C-274, H-271 and CS1), CH-271 (containing C-274 and H-271) and C-CS1 (containing C-274 and CS1) to investigate the mechanism of the fibronectin-mediated inhibitory effect on tumor cell adhesion to laminin as well as fibronectin. These fragments retained cell adhesion-promoting and/or heparin-binding properties when they were immobilized on a surface. Pretreatment of tumor cells with CH-296 or CH-271 suppressed cell adhesion to both laminin and fibronectin. H-271 at the high concentration of 500 micrograms/ml slightly inhibited cell adhesion to laminin (but not to fibronectin), whereas C-274, C-CS1 or a mixture of C-274, H-271 and CS1 (similar molar ratio to CH-296) inhibited cell adhesion to fibronectin but not to laminin. On the other hand, tumor cell adhesion to laminin-substrate was also inhibited by heparin or heparan sulfate, which were able to bind to laminin, suggesting that heparin-like molecules on the cell surface may be included among the laminin receptors. These results indicated that the co-presence of cell- and heparin-binding domains of fibronectin may be required for the fibronectin-mediated inhibitory effect on tumor cell adhesion to laminin, and that the interaction of the heparin-binding domain of fibronectin with the cell surface leads to the inhibition of the cell adhesion to laminin.

Amino Acid Sequence↗
PubMed1991

Recombinant fusion polypeptide with cell- and heparin-binding domains of fibronectin inhibits liver metastasis of L5178Y-ML25 lymphoma cells.

We have investigated the effect of recombinant polypeptides with cell-binding domain (C-274) or with heparin-binding domain (H-271) and their fusion polypeptide (CH-271) on liver metastasis of murine lymphoid tumor. The polypeptides containing heparin-binding domain, H-271 and CH-271, were able to inhibit liver metastasis when co-injected i.v. with L5178Y-ML25 T-lymphoma cells, while C-274 with cell-binding domain showed much weaker antimetastatic activity. Treatment with H-271 or CH-271 substantially prolonged the survival time of mice injected i.v. with L5178Y-ML25 cells. CH-271, containing cell- and heparin-binding domains, was more antimetastatic than H-271. The reason why CH-271 was more effective in inhibiting liver metastasis than H-271 can not be explained in terms of a difference in the stability in the circulation or in the molecular size of the polypeptide. The polypeptides used in this study did not affect the tumor cell growth or viability in vitro. CH-271 was found to be still active in inhibiting liver metastasis even when natural killer cells or macrophages were removed from this system. Furthermore, multiple administrations of CH-271 after tumor implantation effectively inhibited liver metastasis and enhanced the survival rate as compared with H-271, C-274 and untreated control. Thus, the fusion of H-271 with C-274 (i.e. CH-271) augments the antimetastatic property of H-271, possibly through the interaction between tumor cells and the heparin-binding domain of fibronectin.

2-Chloroadenosine↗
PubMed1991

Inhibitory effect of antimetastatic fusion polypeptide of human fibronectin on tumor cell adhesion to extracellular matrices.

We investigated the inhibitory mechanism of liver metastasis by using recombinant fragments with cell- and/or heparin-binding domains (C-274, H-271 or the fusion fragment CH-271). Intravenous co-injection of L5178Y-ML25 cells with CH-271 was more effective for the inhibition of liver metastasis than C-274, H-271 or C-274 + H-271. Reduction of the arrest and retention of the radiolabeled tumor cells in the liver of mice was found when CH-271 was co-injected with tumor cells. L5178Y-ML25 cells adhered both concentration- and time-dependently to the substrates precoated with fibronectin, laminin and reconstituted basement membrane, Matrigel. The tumor cell adhesions to the substrates were inhibited in the presence of CH-271. The tumor cell interaction with CH-271-substrate was inhibited by heparin, and monoclonal antibodies (IST-1 or IST-2) against the heparin-binding domain of fibronectin. However, monoclonal antibodies against the cell-binding domain failed to block the interaction. Similarly, CH-271-mediated antimetastatic activity was also inhibited by the treatment of CH-271 with IST-1 before the co-injection with tumor cells, whereas monoclonal antibody against the cell-binding domain had no effect. Thus, the antimetastatic effect of CH-271 fusion fragment on liver metastasis of L5178Y-ML25 cells may be partly due to interference with the adhesive interaction of tumor cells with extracellular matrix or basement membrane components by a heparin-binding domain-dependent mechanism.

Animals↗
PubMed1991

Cancer incidence in Hawaiian Japanese: migrants from Okinawa compared with those from other prefectures.

Japanese men in Hawaii whose ancestral roots were in Okinawa were compared to Japanese migrants from all other prefectures. The Okinawan migrants have acquired fewer cancers than men from other prefectures (P = 0.12). No one primary site accounts for this difference. Stomach cancer rates showed the largest difference between the two migrant groups. This replicates the experience of Okinawans and non-Okinawans in Japan itself. Lymphosarcoma mortality rates are much higher in Okinawa than in all Japan, but this difference is not reproduced in Hawaiian migrants. This could be explained by a post migrational decrease in HTLV-I-related acute T-cell lymphoma/leukemia. Cancer of the mouth, pharynx and esophagus has decreased in all Japanese migrants, but the decrease is much greater among Okinawan migrants, suggesting they have escaped exposure to risk factors peculiar to the Okinawan environment. Colon cancer is more common in migrant Japanese than in U.S. whites. The dramatic increase in the frequency of this tumor affects Okinawan and non-Okinawan migrants to an equal degree.

Adult↗
PubMed1991

Relatively low prevalence of human papillomavirus 16, 18 and 33 DNA in the normal cervices of Japanese women shown by polymerase chain reaction.

Ninety-two cervical scrapes and tissues, obtained from cytologically or histologically normal cervices of Japanese women, were examined for the presence of human papillomavirus (HPV) 16, 18 and 33 DNA by the polymerase chain reaction (PCR) method. Five out of 92 cases were HPV 16 DNA-positive, but neither HPV 18 nor 33 DNA was detected. The HPV (type 16, 18 and 33) prevalence rate in pregnant women, including postpartum, was 10% (3/31), which was higher than that in non-pregnant women. In two HPV 16-positive cases, we detected HPV 16 DNA again 2 months later. HPV (type 16, 18 and 33) prevalence in normal cervices was shown to be relatively low. However, it is very important to follow up the HPV-positive cases in cytologically normal cervices in order to elucidate the relation between HPV infection and the progression of cervical cancer.

Adolescent↗
PubMed1991

Retinal ganglion cells projecting to the nucleus of the optic tract in the rat.

The nucleus of the optic tract (NOT) has been identified as the link between the retina and the premotor nuclei in the pathway mediating the optokinetic nystagmus (OKN). However, it is still unclear from what parts of the retina and what kinds of retinal ganglion cells the NOT receives visual inputs related to OKN. In the present study, horseradish peroxidase conjugated with wheatgerm agglutinin (WGA-HRP) was injected into the NOT of hooded rats to investigate retrogradely labeled cells in the retina. A solution of WGA-HRP was injected into the NOT through a glass micropipette. Injection sites of the brain and the retina were processed by tetramethyl benzidine protocol and Hanker-Yates method. The labeled cells were observed in the whole area of the retina contralateral to the injection site, while located only in the ventral region of the retina ipsilateral to the injection site. In the retina contralateral to the injection site, a large number of small-sized cells and a few medium-sized cells were labeled diffusely except for surroundings of the optic disc, whereas in the ipsilateral retina there were small and medium-sized cells in the ventral part, being about 8 times greater than those in the contralateral retina. The present study indicates that visual signals responsible for OKN are conducted through the retinal ganglion cells mainly contralaterally, and only from the ventral area of the retina ipsilateral to the injection site.

Animals↗
PubMed1991

Effect of uvulonodular lesions on optokinetic nystagmus and optokinetic after-nystagmus in cats.

To investigate the effect of uvulonodular lesions on horizontal optokinetic nystagmus (OKN) and optokinetic after-nystagmus (OKAN), 6 cats were tested before and after lesions made by ablation under anesthesia. In the 3 cats with only uvular lesion, the initial slow phase velocity and the time constant of OKAN were unchanged. In the remaining three cats whose lesions included not only the uvula but also the nodulus, the time constant of OKAN was markedly prolonged, and the initial OKAN velocity was not affected. The postoperative average time constant of OKAN increased from normal value of 9 s to about 40 s. In contrast, OKN was unchanged in all of the 6 animals. These findings indicate that the nodulus may contribute to the discharge characteristics of the velocity storage integrator.

Animals↗
PubMed1991

EOG findings in patients with lesions in cerebellar peduncles.

EOG tests were performed in patients with lesions in either the superior or the middle cerebellar peduncle, because these patients showed cerebellar signs and symptoms and were difficult to distinguish from patients with cerebellar lesions symptomatically. EOGs of these patients showed a predominant decrease of pursuit gains and OKN velocity gains toward the lesioned side, whereas the percent reduction of fixation-suppression of caloric nystagmus decreased predominantly toward the side contralateral to the lesioned side, regardless of whether lesions were located either in the superior or the middle cerebellar peduncle. The present EOGs are best interpreted as a corresponding to a deficit of the neuronal events of the flocculus in the monkey and are solely ascribed to lesions in the cerebellar peduncles, because even well-defined cerebellar lesions on one side showed bilateral impairments of these visually induced eye movements.

Cerebellar Diseases↗
PubMed1991

Visually induced eye movements in Wallenberg's syndrome.

Eighteen patients with Wallenberg's syndrome were investigated concerning visually induced eye movements. All results were analysed quantitatively using a computer. In 16 out of 18 patients, OKN slow-phase velocities were impaired, in the remaining 2 patients they were normal. Patients who showed impaired OKN were classified into two groups according to directional asymmetry of OKN impairment. In 7 out of the 16 patients, slow-phases toward the lesion side were predominantly impaired in contrast to the slow-phases toward the intact side (group A). In the remaining 9 patients, slow-phases toward the intact side were predominantly impaired (group B). The smooth pursuit showed the same asymmetry as the OKN slow-phase, except, in 4 patients who showed normal smooth pursuit. All patients showed reduced visual suppression of caloric nystagmus during the slow-phase of nystagmus toward the lesion side, except 3 patients who showed normal visual suppression in both directions. CT scan failed to detect either the brainstem or the cerebellar lesions in any cases, but MRI performed on the most recent cases demonstrated the infarctions clearly. These findings suggest that infarctions are localized in the medulla in the patients of group A, but extend to the cerebellum as well as to the medulla in patients of group B.

Adult↗
PubMed1991

Structures of aureobasidins B to R.

Structures of 17 minor forms of aureobasidins (Abs), Abs B-R, were elucidated by mass fragmentation and amino acid analysis. The fragmentation patterns by FAB-MS spectroscopy of Abs A-E seemed to follow predictable rules, so we used the rules to elucidate the 13 other Abs. All Abs consisted of eight amino acids and one hydroxy acid.

Amino Acid Sequence↗
PubMed1991

NMR studies of aureobasidins A and E.

The 1H and 13C NMR spectra of aureobasidins A and E were analyzed by a variety of 2D NMR techniques. Two isomers of aureobasidin A existed as an equilibrium mixture in deuteriochloroform. The isomerism was associated with cis-trans rotation of the amide bond between N-methylphenylalanine and proline. Almost all of the aureobasidin E was found in deuteriochloroform as one conformer; the amide bond between beta-hydroxy-N-methylphenylalanine and proline was in the cis-conformation. Experiments with the NOE made identification of the conformation of the amide bonds of aureobasidins A and E possible.

Amino Acid Sequence↗