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Biomedical subjects

T Nishida

Publications and source records attributed to T Nishida.

At least 433 records · Page 24Linked to original sources
PubMed1992

Two distinct mechanisms for bilirubin glucuronide transport by rat bile canalicular membrane vesicles. Demonstration of defective ATP-dependent transport in rats (TR-) with inherited conjugated hyperbilirubinemia.

Bilirubin is conjugated with glucuronic acid in hepatocytes and subsequently secreted in bile. The major conjugate is bilirubin diglucuronide. Using sealed vesicles which are primarily derived from the canalicular (CMV) and sinusoidal (SMV) membrane vesicle domains of the plasma membrane of hepatocytes, we demonstrated that bilirubin glucuronides are transported by CMV by both ATP- and membrane potential-dependent transport systems. In CMV from normal rats, these processes are additive. In CMV from TR- rats, which have an autosomal recessively inherited defect in biliary secretion of nonbile acid organic anions, ATP-dependent transport of bilirubin diglucuronide was absent whereas the membrane potential driven system was retained. Other canalicular ATP-dependent transport systems, which were previously described for organic cations and bile acids, are functionally retained in TR- rats. Our study indicates that bilirubin glucuronides are primarily secreted into the bile canaliculus by an ATP-dependent mechanism which is defective in an animal model of the human Dubin-Johnson syndrome.

Adenosine Triphosphate↗
PubMed1992

Cardiac musculature of the intrapulmonary vein in the musk shrew.

The cardiac musculature of intrapulmonary veins was examined to elucidate its distribution pattern in the musk shrew, the primitive mammalian type, using by both light and electron microscopies. The musculature was distributed extensively from the hilum to the small veins less than 50 microns in diameter, suggesting that the phylogenic origin of this musculature may be traceable to the primitive mammalian types. Ultrastructure of cardiac myocyte in the intrapulmonary venous walls was essentially similar to that of left atrial myocyte. This suggests that the cardiac musculature may contribute to the regulation of pulmonary blood circulation. The abundance of large lipid droplets in both atrial and pulmonary myocytes was also observed and seemed to be the characteristic ultrastructure related to the physiological condition in this animal.

Animals↗
PubMed1992

Cardiac musculature of the cranial and caudal venae cavae and the pulmonary vein in the fowl.

The cardiac musculature of cranial and caudal venae cavae and pulmonary vein was examined to clarify its distribution pattern in the fowl using both light and electron microscopies. The musculature was distributed from the heart to the root of subclavian vein in the cranial vena cava, to the cranial margin of the liver in the caudal vena cava, and to the left and right distal pulmonary veins in the pulmonary vein, respectively. Judging from the morphology and distribution pattern in the venous wall, the cardiac musculature in the fowl is thought to share the same phylogenic origin with that in mammals. The ultrastructure of cardiac myocytes including transitional cells in the cranial vena cava and the pulmonary vein resembled that of atrial myocytes. While, the typical specialized myocytes such as Purkinje fiber were found in the caudal vena cava of the fowl.

Animals↗
PubMed1992

Fine structure of the parotid gland in the crest-tailed marsupial-rat (Dasyuroides byrnei).

The parotid gland of Dasyuroides byrnei was examined by light microscopy, and transmission and scanning electron microscopy. The acini were composed predominantly of seromucous cells with a few mucous cells. The seromucous cells were light or dark cells containing acidophilic spherical granules of moderate to high electron density and had well-developed cytoplasmic organelles-ordinary mitochondria and large mitochondria with tubular cristae, RER with vesicular or tubular elements, and Golgi apparatus with lamellae, vesicles and vacuoles. The mucous cells had basophilic amorphous granules of low electron density, like those of ordinary mucous cells. The intercalated ducts were composed of simple cuboidal light cells having a few electron-dense granules. The striated ducts consisted of tall columnar light cells containing numerous vesicles and mitochondria with tubular cristae, the same as found in acinar seromucous cells.

Animals↗
PubMed1992

A study of the role of sex hormones in rat ovarian cancer.

The effects of estrogen, progesterone, and testosterone on the growth of 7,12 dimethylbenz(a)anthracene (DMBA) induced adenocarcinomas in rats (Wistar strain) were evaluated. Estrogen resulted in the highest acceleration of tumor volume. The histologic features were a solid structure associated with a significant proliferation of connective tissues and with many signet ring cells with intracytoplasmic canaliculi. Progesterone changed the histologic features to a more immature adenocarcinoma associated with a notable solid area with many mitotic figures, although the growth rate of the tumor was the same as the controls. On the contrary, testosterone induced the slowest tumor growth and a histologically scirrhus pattern. The results of this preliminary observation indicate a possible role for sex steroids in the ovarian tumorigenic process.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1992

Transforming growth factor-beta modulates effects of epidermal growth factor on corneal epithelial cells.

In order to understand the mechanisms that bring about maintenance and restoration of the integrity of corneal epithelium, we investigated independent and combined effects of transforming growth factor-beta (TGF-beta) and epidermal growth factor (EGF) on rabbit corneal epithelial cells in cell and organ culture. Specifically, we determined whether incubation with these factors influenced 1) cellular proliferation, 2) ability of cells to attach to a fibronectin matrix, and 3) the rate of epithelial migration over corneal stroma. Incubation with TGF-beta caused a dose-related decrease in the incorporation of 3H-thymidine by the epithelial cells. EGF increased 3H-thymidine incorporation, but this effect was antagonized by the addition of TGF-beta into the incubation medium. Incubation with EGF increased the numbers of cells that attached to a fibronectin matrix. TGF-beta itself did not affect the number of attached cells but, again, it antagonized the stimulatory effect of EGF. Similarly, when corneal blocks were cultured with EGF, epithelial migration increased in a dose-related manner. TGF-beta itself did not affect epithelial migration at any of the concentrations tested (0.1-10 ng/ml), but it antagonized EGF-stimulated epithelial migration. These findings suggest that the proliferation and the migration of corneal epithelial cells are regulated by different mechanisms, and that TGF-beta serves as a modulator of the effects of EGF.

Animals↗
PubMed1992

[Immunohistochemical studies of recessive oncogene p53 and N-myc oncogene expression in 7, 12 dimethylbenz (a) anthracene-induced rat ovarian tumors].

In the present study, the expressions of p53 and N-myc gene were analyzed immunohistochemically in rat ovarian tumors induced by 7,12 dimethylbenz (a) anthracene (DMBA). 1) p53 could be seen in the nucleolei of tumor cells. The positive rates were: adenomas 17%, adenocarcinomas 37%, sarcomas 0%, mixed müllerian tumor 0% and epidermal cysts 100%. Neither the serial-allografted tumor nor DMBA-OC-1 was positive. 2) N-myc could be seen in the cytoplasm and perinuclear cytoplasm of tumor cells. The positive rates were: adenomas 33%, adenocarcinomas 77%, sarcomas 100%, mixed müllerian tumors 100% and epidermal cysts 100%. Both the serial-allografted tumor and DMBA-OC-1 were positive. 3) The positive rates in both p53 and p21 were: adenocarcinoma 20% and epidermal cysts 100%. The positive rates in both N-myc and p21 at the were: adenoma 17%, adenocarcinoma 50%, sarcoma 33%. Both the serial-allografted tumor and DMBA-OC-1 were positive. Only two cases were positive for p53, N-myc and p21. p53 was detected in most of the adenomas. 4) The positive rate for both N-myc and p21 was higher than that for both p53 and p21. This was similar to other reports. The results suggested that p53 plays a role in precancerous tumor as a recessive oncogene. It was supposed that tumors with N-myc gene expression were had malignant growth characteristics.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1992

Coordinated appearance of beta 1 integrins and fibronectin during corneal wound healing.

Fibronectin, which appears at wound sites, serves as a temporary matrix for the epithelial migration involved in healing. Cellular responses to fibronectin have not yet been elucidated. We visualized beta 1 integrins, fibronectin, laminin, and collagen type IV by immunofluorescence techniques at various intervals after single, nonpenetrating incision in the corneas of rats to investigate the chronologic changes in the localization of these proteins during corneal epithelial wound healing. In unwounded corneas beta 1 integrins were found on basal cells of the corneal epithelium and fibronectin was found in the corneal subepithelial region, at Descemet's membrane, and in streaks between collagen fibers of the stroma. Both laminin and collagen type IV were found in the subepithelial region and Descemet's membrane. Immediately after the incision, fibronectin was visible on the surface of the V-shaped defect of the stroma; epithelial cell expressed beta 1 integrins began to migrate over the defect and to fill it. When healing was almost completed, beta 1 integrin staining of epithelial cells diminished, except for in basal cells. Staining of fibronectin diminished at the interface between the new epithelium and the stroma. Laminin and collagen type IV were not seen between the migrating epithelial cells and the underlying stroma until epithelial cells completely covered the defect. Appearance and disappearance of beta 1 integrins and fibronectin are thus well coordinated during corneal epithelial wound healing process, suggesting an active involvement of beta 1 integrins and fibronectin.

Animals↗
PubMed1992

Epidermal growth factor stimulates corneal epithelial cell attachment to fibronectin through a fibronectin receptor system.

Epidermal growth factor (EGF) stimulates corneal epithelial migration in vivo and in vitro. Antibody against fibronectin inhibits this effect in vitro, suggesting that a fibronectin-dependent mechanism in involved. To elucidate the action of EGF, we placed rabbit corneal epithelial cells, preincubated in the absence or presence of EGF (10 ng/ml), into wells coated with fibronectin. After 45 minutes of incubation, the numbers of cells attached to the wells were counted. Preincubation with EGF for 6 hr was not effective, but preincubation for 9 hr significantly increased the numbers of cells attached to the wells. These numbers were not increased further by additional preincubation. When concentrations of EGF were reduced, numbers of attached cells decreased proportionally, but remained significantly higher than the numbers obtained with cells not exposed to EGF. The EGF-stimulated attachment to the fibronectin matrix was inhibited in a dose-dependent fashion by antifibronectin IgG and by GRGDSP, a synthetic peptide that mimics the amino acid sequence of the cell-binding domain of fibronectin. The authors conclude that a fibronectin/fibronectin receptor system mediates EGF-induced stimulation of cellular attachment. These findings suggest that EGF may increase the expression of fibronectin receptors.

Amino Acid Sequence↗
PubMed1992

[A case report of two mitral valve aneurysms with one perforation after two attacks of infective endocarditis].

Aneurysms of the mitral valve complicating infective endocarditis (IE) are uncommon. The patient was a 57-year-old man who was admitted to our hospital for a precise examination of heart failure. One year before, the first two-dimensional echocardiography showed an aneurysm of the anterior mitral leaflet possibly due to a previous attack of IE. Doppler color flow mapping detected a regurgitant jet from the mitral valve aneurysm into the left atrium during systole, which suggested perforation of the aneurysm, and an aortic regurgitant jet flowing against the anterior mitral leaflet. Because the patient's family refused cardiac catheter examination and surgery, we treated him in the out-patient clinic. A few weeks before his admission, he had discontinued taking diuretics because of uncomfortable urinary frequency. He gradually developed the symptoms of heart failure and entered our hospital. IE was suspected because of leucocytosis and slight fever. Two-dimensional echocardiography revealed a new aneurysm of the anterior mitral leaflet without perforation, located in the distal part of the old aneurysm. This time, his family consented to the surgical treatment. Aortic and mitral valve replacement was successfully performed. It was pathologically confirmed that the two mitral aneurysms had been caused by IE.

Aortic Valve↗
PubMed1992

Increased lysosomal enzyme activity of keratocytes after endocytosis of foreign particles.

It has been reported that keratocytes endocytose foreign particles both in vitro and in vivo, suggesting the active participation of keratocytes in corneal wound healing and host defense mechanism. To understand the cellular response and the fate of engulfed foreign particles, we investigated the changes in the lysosomal enzyme activities after keratocytes endocytosed latex beads or glutaraldehyde-fixed Staphylococcus aureus. Acid phosphatase activity in the cells endocytosing either latex beads or fixed bacteria increased significantly as compared with that in the control over the period of 12 hours. Changes in acid phosphatase activity depended on both the incubation periods and the amount of latex beads or bacteria added. The activity reached a plateau after 6 hours of incubation. When keratocytes endocytosed latex beads, the activity of N-acetyl-beta-D-glucosaminidase in the cells showed an increase similar to that of acid phosphatase. However, the N-acetyl-glucosaminidase activity in the cells endocytosing fixed bacteria did not increase significantly. These findings suggest that endocytosing keratocytes increase degrading enzyme activities in the cells to break down engulfed foreign particles. It is also suggested that the intracellular response is varied according to the character of the engulfed materials.

Acetylglucosaminidase↗
PubMed1991

Early changes of alpha B-crystallin mRNA in rat skeletal muscle to mechanical tension and denervation.

alpha B-Crystallin specifically decreases in atrophied rat soleus muscle with hindlimb suspension (HS). alpha B-Crystallin cDNA was cloned from rat heart cDNA library using oligonucleotide probe, and its complete coding and partial non-coding regions were sequenced. Northern blot analysis revealed that alpha B-crystallin mRNA in slow muscle decreases at 36 hour after HS but recovered at 24 hour after HS stopped. Denervation decreased the expression of alpha B-crystallin mRNA in slow muscle but increased it in fast muscles, which hardly expressed in normal condition. Passive tension increased the expression of alpha B-crystallin mRNA in both muscle types. Based upon these Northern blot analysis of alpha B-crystallin, nerve innervation and external load on muscle are essential regulatory factors on the expression of the mRNA of alpha B-crystallin in rat skeletal muscle.

Actins↗
PubMed1991

Promyelocytic leukemia cell line, HL-60, produces human hepatocyte growth factor.

The human promyelocytic leukemia cell line, HL-60, stimulated with PMA, produced human HGF-like immunoreactivity (HL-60 HGF), which was detected with human HGF-specific ELISA. The purified HL-60 HGF was indistinguishable from human HGF in the plasma of patients with fulminant hepatic failure by studies of subunit constitution and amino acid composition. The HL-60 HGF mRNA corresponded to 6 kb, which was consistent with previous reported data in rat and human HGF mRNA, was detected in stimulated HL-60, by northern hybridization analysis using human HGF cDNA probe. These findings indicated that HL-60 HGF was identical to, or closely resembled, human plasma HGF. The HL-60 cell is an attractive model for studies of HGF-producing mechanisms, the manner of secretion and the nature of induction signals.

Amino Acids↗
PubMed1991

Blepharophimosis sequence and de novo balanced autosomal translocation [46,XY,t(3;4)(q23;p15.2)]: possible assignment of the trait to 3q23.

We report on a boy with the blepharophimosis sequence and de novo, apparently balanced reciprocal translocation between 3q23 and 4p15.2 [46,XY,t(3;4)(q23;p15.2)de novo]. Possible assignment of this autosomal dominant disorder is discussed. A 3q23 band is a more preferable gene locus of the belpharophimosis sequence, based on the comparison of clinical manifestations between 4p- and 3q-syndromes.

Blepharophimosis↗
PubMed1991

Rat liver canalicular membrane vesicles contain an ATP-dependent bile acid transport system.

The secretion of bile by the liver is primarily determined by the ability of the hepatocyte to transport bile acids into the bile canaliculus. A carrier-mediated process for the transport of taurocholate, the major bile acid in humans and rats, was previously demonstrated in canalicular membrane vesicles from rat liver. This process is driven by an outside-positive membrane potential that is, however, insufficient to explain the large bile acid concentration gradient between the hepatocyte and bile. In this study, we describe an ATP-dependent transport system for taurocholate in inside-out canalicular membrane vesicles from rat liver. The transport system is saturable, temperature-dependent, osmotically sensitive, specifically requires ATP, and does not function in sinusoidal membrane vesicles and right side-out canalicular membrane vesicles. Transport was inhibited by other bile acids but not by substrates for the previously demonstrated ATP-dependent canalicular transport systems for organic cations or nonbile acid organic anions. Defects in ATP-dependent canalicular transport of bile acids may contribute to reduced bile secretion (cholestasis) in various developmental, inheritable, and acquired disorders.

Adenosine Triphosphate↗
PubMed1991

Comparison of the amino acid and nucleotide sequences between human and two guinea pig major basic proteins.

By means of reverse-phase HPLC, 2 different proteins were obtained from apparently purified pig eosinophil major basic protein (MBP) and these proteins were named GMPB1 and GMBP2. It was revealed that these 2 components of MBP have similar molecular weights and pI values, although the amino acid compositions were slightly different. In the previous study, we cloned and sequenced GMPB1 cDNA. Here we obtained another clone by plaque hybridization using a screening probe synthesized by means of polymerase chain reaction. After sequencing, it became apparent that this clone corresponded to GMBP2. As in the case of GMBP1, the cDNA of GMBP2 encoded pre-proGMBP2 with 3 domains; signal peptide, acidic pro-portion, and mature GMBP2. By comparing the sequences of GMBP1 and GMBP2, it was revealed that the proteins were quite similar to each other. In addition, their sequences also resembled those of human MBP, especially in the basic domain of mature protein; but no such similarity existed in the pro-portion. Although the molecular weights determined by SDS-PAGE of guinea pig and human MBPs were 11,000 and 9,300, respectively, the calculated molecular weights of these 3 MBPs were all 13.8 kDa. The calculated pI values of GMBP1, GMBP2 and human MBP were 11.7, 11.3 and 11.6, respectively. By means of Harr plot analysis, it was revealed that the amino acid sequences, not only in signal peptides but also in the basic domains of mature proteins, were well conserved between guinea pig and human MBPs.

Amino Acid Sequence↗