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Biomedical subjects

N Azuma

Publications and source records attributed to N Azuma.

At least 37 records · Page 2Linked to original sources
PubMed1989

[Experimental studies on microphthalmos formation in neonatal rats treated with monosodium-L-glutamate].

Changes in the eyeball size were investigated in rats treated with monosodium glutamate (MSG) during the neonatal period. Correlations among ocular size and degenerative changes of the retina and optic nerve were also studied ophthalmoscopically and histologically. Rats received MSG 5 times, 2 times or once. In rats which received MSG 5 times, the administration was made at 1, 3, 5, 7 and 9 days of birth. In rats, which received MSG 2 times, the administration was made on 2 subsequent days (1 and 2, 3 and 4, 5 and 6, 7 and 8, 9 and 10, 12 and 13 or 15 and 16 postnatal days). In the group of rats, which received MSG once, the administration was made on each from the 1st to the 15th postnatal day. Microphthalmos formation was clearly observed only in rats with 5 times and 2 times (9 and 10 days) injection of MSG. In these rats, narrowing of retinal vessels, paleness and excavation of optic disks were observed ophthalmoscopically. Total liquefaction of the vitreous body were seen in the same groups. Histological examinations also revealed degeneration of the inner layers of the retina. These findings indicated that the administration of MSG at critical stages during postnatal development induces disturbances of eyeball growth. It was also suggested that the growth of the eyeball is closely associated with the postnatal development of the retina.

Animals↗
PubMed1989

[Morphological studies on cataract and small lens formation in neonatal rats treated with monosodium-L-glutamate].

Changes in the transparency and size of lenses in rats were investigated following administration of monosodium-L-glutamate (MSG), MSG (5 mg/g b.w.) was injected subcutaneously on the 9th and 10th days after birth. Morphological changes of the lenses were examined ophthalmoscopically and histologically. Ophthalmoscopically, localized opacity was apparent at the posterior pole of the lens corresponding to the attached portion of hyaloid artery at 1 months of age. The incidence of cataract increased with age, reaching more than 75% at 4 months of age. Morgagni's globules were histologically detected in the opacity of the posterior lens cortex. Degenerative changes of the lens epithelium were observed in the mature cataract. However, the capsules of the lens were well preserved. The size and weight of the lens were smaller than those of controls. Although the pathogenesis of the cataract and small lenses are not clear at the moment, these findings indicate that administration of MSG could be an etiologic factor in cataract formation in the developing rat.

Animals↗
PubMed1988

Preparation of subfragment-1 from abalone smooth muscle myosin.

Myosin subfragment-1 (S1), which has one heavy chain (HC) (93 kDa) and two light chains (LC1 and LC2), was prepared by papain digestion of myosin from abalone-smooth muscle in the presence of Ca2+. The Ca-sensitivity of abalone S1 itself was not lost completely (about 30%). The tryptic digestion of S1 showed that in the presence of EDTA, S1 HC was split into 68, 55, and 23 kDa fragments, as in the presence of Ca2+, but 23 kDa was further degraded into 19 kDa. In contrast to the result in the presence of Ca2+, LCs disappeared in the early stage of reaction and Ca-ATPase activity decreased rapidly to about 70% of that of intact S1. This rapid decrease of Ca-ATPase activity seemed to be accompanied with the digestion of LCs. Therefore, LCs contribute to the protection of 23 kDa fragment from further digestion, to the maintenance of Ca-ATPase activity by stabilizing the structure of S1 to some extent in the presence of Ca2+. Since F-actin suppressed the cleavage of S1 HC to 68 and 23 kDa during tryptic digestion, it might be that 23 and 68 kDa corresponded to 20 kDa (C-terminal fragment) and to 50 + 25 kDa (N-terminal fragment) of skeletal myosin S1, respectively.

Actins↗
PubMed1988

Preliminary observation on pancreatic duct adenocarcinoma induced by intraductal administration of N-ethyl-N'-nitro-N-nitrosoguanidine in dogs.

Pancreatic duct adenocarcinoma was induced by intraductal administration of N-ethyl-N'-nitro N-nitrosoguanidine (ENNG) in two mongrel dogs. A dog received a total dose of 595 mg of ENNG during 12 months and was sacrificed. Duct obstruction was detected by pancreatography and duct adenocarcinoma was found. Another dog was given a total dose of 350 mg of ENNG during 8 months and was sacrificed 26 months after the first administration of the carcinogen. Duct adenocarcinoma was found. No pancreatic tumors were found in 2 dogs given intraperitoneal N-nitrosobis(2-oxopropyl)amine at a total dose of 4000 mg or in 2 dogs given Tween 60 only. These results suggest that the direct presence of a carcinogen in the pancreatic duct was able to induce duct adenocarcinoma in dogs.

Adenocarcinoma↗
PubMed1987

Purification and characterization of a novel metalloendopeptidase from Streptococcus cremoris H61. A metalloendopeptidase that recognizes the size of its substrate.

An endopeptidase (LEP-II), which has a unique substrate specificity, was purified to homogeneity by conventional chromatographic techniques from Streptococcus cremoris H61. The enzyme was a metalloendopeptidase since it was inhibited by EDTA and 1,10-phenanthroline; the metal-depleted enzyme could be fully reactivated by micromolar levels of Zn2+ and was not inhibited by specific inhibitors for serine or thiol protease. The molecular mass of the enzyme was estimated to be 80 kDa by Sephacryl S-300 gel filtration and high-performance liquid chromatography with a TSK-G3000SW column. The enzyme consisted of two identical subunits and the N-terminal sequence of LEP-II was determined up to the 19th residue. Although the enzyme had a broad substrate specificity it specifically hydrolyzed the peptide bonds involving the amino groups of hydrophobic amino acid residues. Various small polypeptides, such as alpha s1-CN(f1-23), alpha s1-CN(f91-100), oxidized insulin B chain, glucagon and some biologically active peptides were hydrolyzed. However, a variety of larger polypeptides or proteins, such as alpha s1-CN(f1-54), alpha s1-CN(f61-123), alpha s1-CN(f136-196), alpha s1-casein, beta-casein, and kappa-casein were not hydrolyzed. LEP-II recognized the size of its substrates, which were limited below a molecular mass of about 3.5 kDa.

Amino Acids↗
PubMed1987

A glyco-phosphoprotein in human milk.

A highly glycosylated phosphoprotein (HGPP) was isolated from a human casein fraction by reversed-phase high-performance liquid chromatography. This component contained carbohydrates to approximately 38.2% (w/w) and phosphorus to approximately 1.6% (w/w). The molecular weight of this HGPP as estimated by sodium dodecyl sulphate-polyacrylamide gel electrophoresis approximately 41,000. Ultracentrifugal analysis revealed that the sedimentation coefficient of the HGPP was 2.6S in a buffer at pH 7.0 and 27 degrees C, but this component interacted with human k-casein and formed a complex with s = 10.4S.

Chromatography, High Pressure Liquid↗
PubMed1987

Common duct carcinoma and obstruction in female hamsters treated with N-nitrosobis(2-oxopropyl)amine and/or cholecystectomy.

Detailed histologic observations were performed on the head of the pancreas of hamsters treated with 10 mg/kg body weight N-nitrosobis(2-oxopropyl)amine (BOP) once a week for 6 weeks with or without cholecystectomy. Cholecystectomy was performed 5 weeks before starting BOP initiation. The incidence of head cancers was 100% and cholecystectomy did not affect pancreatic carcinogenesis by BOP. Common bile duct dilatation was produced by advanced pancreatic head carcinomas and microadenocarcinomas in common duct. Micro-adenocarcinomas were not macroscopically detected since the tumors were located in the lumen of common duct.

Adenocarcinoma↗
PubMed1987

[Absorption of 5-FU orally administered in a patient with postoperative gastric cancer under artificial dialysis].

A patient under artificial dialysis due to chronic renal failure suffered from gastric cancer concurrently. This patient underwent subtotal gastrectomy followed by consecutive oral administration of 5-FU (tablets) as a postoperative adjuvant chemotherapy. The 5-FU level in the peripheral blood on oral administration at 50 mg remained at 0.007-0.01 microgram/ml over 2 hours. This feature of 5-FU blood level is not seen in gastric cancer patients with normal renal functions on administration of 5-FU tablets, and it seems to approximate the features of a 5-FU prodrug level in the blood upon oral administration. Neither the influence of dialysis on the absorption of orally administered 5-FU nor side effects caused by 5-FU were observed. The above findings suggest that it may be possible to maintain a certain blood level of 5-FU and to perform adjuvant chemotherapy even in cancer patients under artificial dialysis, as long as the dose is controlled carefully.

Administration, Oral↗
PubMed1986

Electron microscopic study of the developing human vitreous collagen fibrils.

Vitreous fibrils, and collagen fibrils in other ocular tissues, were observed in 5-, 6- and 7-weeks human embryos. The vitreous fibrils in 7-weeks embryos were distinctly different from the fibrils of other ocular tissues. The vitreous fibrils near the rim of the optic cup were similar to the fibrils in the anterior cavity of the lens vesicle in the 6-week embryo. Broad fibrils were demonstrated with a diameter of 30-40 nm and a striated banding pattern of about 60 nm periodicity.

Collagen↗
PubMed1985

Morphological study on the human developing vitreous collagen fibrils and persistent hyperplastic primary vitreous.

The human primary vitreous fibrils were similar to the secondary vitreous fibrils on electron microscopic observation. On the other hand, the intravitreal strand in a persistent hyperplastic primary vitreous (PHPV) contained large numbers of collagenous fibrils with 40-50 nm diameters and about 65 nm cross-striation periodicity. Besides these, other types of noncross-striated fibrils, ranging in diameter from 10 to 30 nm were observed in the circumferential region of the intravitreal strand. Moreover, there was complete morphological continuation between the intravitreal strand and the optic disc. Their histochemical properties were very likely collagenous and in part glial. Although the results are based only on 1 case of PHPV, present observations showed that components of the intravitreal strand of PHPV considerably differed from the primary vitreous.

Collagen↗
PubMed1985

A 20,000-dalton casein fragment in human milk.

A new peptide of 20,000 daltons was found in human milk as a constituent of the casein micelle. Enzymic digestion with plasmin or trypsin revealed that the peptide was identical with a degradation product of human beta-casein. The amino acid composition of the degradation product and the previously reported sequence in the N-terminal region of human beta-casein suggested that the peptide was a fragment of beta-casein lacking the C-terminal region. The thermal sensitivity of this peptide was higher than that of beta-casein, but the peptide lost the property of calcium-dependent precipitation, which intact beta-casein possesses.

Amino Acid Sequence↗
PubMed1976

Calcium sensitivity of abalone, Haliotis discus, myosin.

Superprecipitation was observed with abalone myosin and purified rabbit actin in the presence of calcium ions, but was not observed in the absence of calcium. The Mg-ATPase [EC 3.6.1.3] activity of abalone myosin and rabbit actin in the absence of calcium ions (EGTA present) showed about 60% inhibition as compared with values in the presence of calcium ions. The calcium sensitivity may be attributable to abalone myosin, as in the case of scallop myosin.

Actins↗
PubMed1975

Myosin from molluscan abalone, Haliotis discus. Isolation and enzymatic properties.

Actomyosin was extracted from smooth muscle of molluscan abalone with 0.1 M PPit pH 6.4. Myosin was separated from the actomyosin by centrifugation at 100,000 X g in the presence of 5 mM ATP and 10 mM MgCl2. Myosin in the supernatant was further purified by gel filtration on a Sepharose 4B column. Paramyosin contamination of the actomyosin preparation interfered with the isolation of myosin and complete removal of actin and paramyosin from the myosin has not been accomplished. The myosin appeared to consist of a single f-chain and a single g-chain, as examined by SDS-disc electrophoresis in 8 or 13.7% acrylamide gel. The ATPase [EC 3.6.1.3] activity of this myosin in 0.5 M KCL at neutral pH and at 0 degrees was rather unstable and decreased by 10-20% per day. The effects of rho-chloromercuribenzoate and EDTA on the ATPase activity were similar to those observed with other smooth muscle myosin but the dependence upon pH or KCL concentration was different.

Adenosine Triphosphatases↗