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Biomedical subjects

R Kato

Publications and source records attributed to R Kato.

At least 325 records · Page 18Linked to original sources
PubMed1992

[Spontaneous cerebrospinal fluid otorrhea in a normal inner ear. A case report].

A 49-year-old male with spontaneous cerebrospinal fluid (CSF) otorrhea, an extremely rare condition, is presented as the third reported case in Japan. The patient visited us complaining of sudden hearing loss and fullness of the ear on the left side. A tegmen defect of the posterior cranial fossa and CSF leakage from the fistula into the mastoid air cells, but a normal inner ear, were found by means of metrizamide CT. The fistula was surgically occluded with fascia temporalis and an artificial bone with fibrin glue. The CSF otorrhea from the tegmen defect was successfully stopped by this procedure and no recurrence has been observed. We discuss this extremely rare disease in this paper.

Cerebrospinal Fluid Otorrhea↗
PubMed1992

[Local recurrence of differentiated thyroid carcinoma effectively treated by local injection of OK-432].

Local recurrence of differentiated thyroid carcinoma in a 67-year-old woman was treated by topical injection of OK-432 every 2-4 weeks. Recurrent tumors turned into small scar-like tissues after 9 months of OK-432 administration. The bleeding from the tumor was well controlled. Secondary recurrent tumors were also effectively treated in the same manner. About 2 years have passed since the start of the treatment and the local recurrence is well controlled. We conclude that topical injection of OK-432 might be a good modality of treatment for the local recurrence of thyroid carcinoma.

Carcinoma↗
PubMed1992

[Nd-YAG laser therapy of tracheobronchial lesions by malignant tumor].

Thirty-seven patients with tracheobronchial lesions by malignant tumor were treated with Nd-YAG laser. Thirty-seven patients were twenty-three males and fourteen females and ages ranged from 34 to 79 years. Diseases included were primary tracheal tumor in 3 cases, lung cancer in 16 (8 squamous cell carcinoma, 5 adenocarcinoma, 2 large cell carcinoma, 1 small cell carcinoma), cancer of adjacent organs in 9 (5 thyroid cancers, 4 esophageal cancers), and metastatic cancer to the lung or mediastinal lymph nodes in 9 (4 renal cell carcinoma, 2 thyroid cancer, one patient respectively, colon cancer and breast cancer). Intermittent irradiation of YAG laser was done for 0.5 second at 30-40 Watt through flexible bronchoscope under local anesthesia. It was repeated 1 to 41 times (mean 4.1 times) and energy amount was 148 Joules to 18,513 Joules (mean 3,305 J). The result was; stenosis disappeared in 22 cases (59.4%), improved in 14 (37.8%), and in one case YAG laser therapy discontinued due to intractable bleeding. The Nd-YAG laser therapy for tracheobronchial lesions by malignant tumor is very useful to improve dyspnea or atelectasis.

Adult↗
PubMed1991

Assay for type III collagenolytic activity in lung cancer tissue.

We developed a method for measuring the activity of type III collagenolytic enzyme in lung cancer tissue, using as substrate, type III collagen purified from human placenta. In this method [3H]propionate is used for labeling type III collagen, with bacterial collagenase used for making the standard curve. It, therefore, becomes possible to compare type III collagenolytic activity with those of other collagen subtypes (types I and IV). As this method is a fibril assay it is not susceptible to trypsin or other proteases. The average type III collagenolytic enzyme activity was higher in squamous cell carcinoma than in adenocarcinoma, while that of lung cancer tissue exceeded that of normal lung tissue. The activity of type III collagenase increased with the progression from one disease stage to the next.

Adenocarcinoma↗
PubMed1991

Vascular smooth muscle contraction induced by Na+ channel activators, veratridine and batrachotoxin.

The effects of the sodium channel activators veratridine and batrachotoxin on isolated rat aorta were investigated. Veratridine caused gradual contraction, independent of the presence of endothelium, with an EC50 of 35 microM. Batrachotoxin (1 microM) also induced contraction. Both effects were completely inhibited by the sodium channel blocker tetrodotoxin (1 microM). The veratridine (60 microM)-induced contraction was inhibited by nifedipine (0.1 microM). In the absence of extracellular Ca2+, veratridine (60 microM) did not cause contraction. Sodium nitroprusside (80 nM), acetylcholine (10 microM) and isoproterenol (1 microM) caused relaxation of rings precontracted with veratridine (60 microM). An inhibitor of endothelium-derived relaxing factor (EDRF) synthase, N omega-nitro-L-arginine methyl ester (L-NAME) (0.65 mM), enhanced the veratridine-induced contraction in rings with an intact endothelium, which suggests that EDRF was being released during the veratridine-induced contraction. These results show that the activation of sodium channels on smooth muscle cells induces a contraction that is probably mediated by Ca2+ influx through voltage-dependent Ca2+ channels.

Animals↗
PubMed1991

Active site of mu-conotoxin GIIIA, a peptide blocker of muscle sodium channels.

The amino acid sequence of mu-conotoxin GIIIA (otherwise called geographutoxin I), a peptide having 22 amino acid residues with three disulfide bridges, was modified by replacing each residue with Ala or Lys to elucidate its active center for blocking sodium channels of skeletal muscle. NMR and CD spectra were virtually identical between native and modified toxins, indicating the similarity of their conformation including disulfide bridges. The inhibitory effect of these modified peptides on twitch contractions of the rat diaphragm showed that Arg at the 13th position and the basicity of the molecule are crucial for the biological action. The segment Lys11-Asp12-Arg13 has been reported to be flexible (Lancelin, J.-M., Kohda, D., Tate, S., Yanagawa, Y., Abe, T., Satake, M., and Inagaki, F. (1991) Biochemistry, in press), and this may represent a clue for the subtle fit of Arg13 to the specific site of sodium channels. Since known ligands to sodium channels, such as tetrodotoxin, anthopleulin-A, etc., contain guanidino groups as a putative binding moiety, Arg may be a general residue for peptide toxins to interact with the receptor site on sodium channels.

Amino Acid Sequence↗
PubMed1991

A gene structure of testosterone 6 beta-hydroxylase (P450IIIA).

Genomic clones of a rat testosterone 6 beta-hydroxylase have been isolated and characterized as the first gene (P450/6 beta A) among P450IIIA subfamily. This gene spans about 25Kb and consists of 13 exons, which is the largest number of exons among cytochrome P-450 genes reported previously. The nucleotide sequence of the exon region showed high similarity to those of P450PCN2 and P450PCN1 cDNA (Gonzalez, F.J. et al. (1987) Mol. Cell. Biol. 2969-2974), but several replacements and deletions of nucleotide were found between the P450/6 beta A gene and both cDNAs, indicating the existence of multiple P450IIIA genes in rats.

Animals↗
PubMed1991

An arylamine acetyltransferase (AT-I) from Syrian golden hamster liver: cloning, complete nucleotide sequence, and expression in mammalian cells.

A cDNA clone (designated hamAT101) encoding an arylamine acetyltransferase, AT-1, was isolated from a hamster liver lambda gt11 cDNA library using a specific polyclonal antibody raised against AT-1. The cloned cDNA insert consisted of 1181 nucleotides, including an open reading frame of 870 nucleotides encoding 290 amino acid (Mr 33,503). The isolated cDNA displayed high sequence similarity to those of chicken, rabbit, and human acetyltransferases. In Northern blots, the hamAT101 cDNA probe hybridized to an RNA band of 18S in the livers of both slow and rapid acetylator phenotypes. To confirm that hamAT101 cDNA encodes the monomorphic but not the polymorphic protein, the isolated cDNA was expressed in monkey kidney cells (COS-1 cells) using the vector p91023(B). A protein with a molecular weight similar to that of AT-1 was detected upon Western blotting in the 9000 x g supernatant from the transfected cells. The activity toward four different substrates of the 9000 x g supernatant was also examined. In agreement with the results of purified AT-1, the cDNA-expressed protein exhibited a high capacity for N-acetylation of 4-aminoazobenzene and 2-aminofluorene, and O-acetylation of 2-hydroxyamino-6-methyldipyrido [1,2-a:3',2'-d] imidazole, whereas no activity was found for the N-acetylation of p-aminobenzoic acid. These results, in addition to the RNA blot hybridization, indicate that hamAT101 encodes the hamster acetyltransferase AT-1.

Amino Acid Sequence↗