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Biomedical subjects

M Niwa

Publications and source records attributed to M Niwa.

At least 307 records · Page 17Linked to original sources
PubMed1991

Immunohistochemical localization of Zn-alpha 2-glycoprotein in normal human tissues.

The Zn-alpha 2-glycoprotein (Zn-alpha 2-GP) is present at a high concentration in the seminal plasma and at significant levels in other human body fluids. Its precise localization, however, has remained unclear, as well as its physiological and pathological significance. The present study reports the immunohistochemical localization of this protein in normal adult human tissues. Localization of the reactive product to anti-human plasma Zn-alpha 2-GP antibody was demonstrated in the following cells: luminal and basal cells of the prostate gland, luminal epithelial cells of the acini and of some ducts of the mammary glands, luminal cells of the secretory portion of the eccrine and apocrine sweat glands, serous cells of the salivary, tracheal, and bronchial glands, acinar cells of the esophageal glands, exocrine acinar cells of the pancreas, hepatocytes of the liver, and epithelial cells of the proximal and distal tubules in the kidney. The present results suggest that Zn-alpha 2-GP exerts some unknown but fairly widespread exocrine function and may be produced in the various epithelial cells tested. Hepatocytes are also suggested to be a source of the protein in the blood plasma.

Adult↗
PubMed1991

Specific 125I-endothelin-1 binding sites in the central nervous system.

The quantitative receptor autoradiographic method we used revealed that specific 125I-endothelin-1 (125I-ET-1) binding sites are highly concentrated in the choroid plexus (ChP), subfornical organ (SFO), lacunosum molecular layer of the hippocampus (LMol) and granular layer of the cerebellum (GC) of the rat brain. High densities of the binding sites were also observed in the laminae I-III and intermediolateral nucleus of the porcine spinal cord. 125I-ET-1 bound to the rat ChP and LMol with a high-affinity and to the SFO and GC with a low-affinity. The possibility that ET-1 acts as a neuropeptide within the central nervous system by interacting with specific receptors would have to be considered.

Animals↗
PubMed1991

Brain natriuretic peptide binding sites in rat kidney.

Specific binding sites for [125I] porcine brain natriuretic peptide-26 ([125I]BNP-26) were investigated in the rat kidney by using receptor autoradiographic and membrane binding techniques. The binding sites were discretely localized in the glomeruli and inner medulla. There were no differences between the localization of [125I] BNP-26 and [125I] alpha-rat ANP binding sites. [125I]BNP-26 binding to solubilized membranes from isolated glomeruli of the rat kidney was saturable, and a single class of high-affinity sites. [125I]BNP-26 bound to two sites in solubilized inner medullary membranes. The rank order of potency to inhibit binding was BNP-26 = alpha-rat ANP (1-28) greater than atriopeptin III [ANP-(103-126)] much greater than atriopeptin I [ANP(103-123)] greater than des-Cys105, Cys121-ANP-(104-126). The possibility that BNP-26 regulates, as a circulating hormone, kidney functions by binding to ANP receptors would have to be considered.

Animals↗
PubMed1991

Hippocampus and frontal cortex are the potential mediatory sites for convulsions induced by new quinolones and non-steroidal anti-inflammatory drugs.

The combined administration of enoxacin, a new quinolone, and fenbufen, a non-steroidal anti-inflammatory drug induced convulsions in mice, but convulsion did not occur when a single administration of each drug was given. Inhibition by enoxacin of [3H]muscimol binding to mouse and human brain membranes was remarkably facilitated by fenbufen. These inhibitions were much more prominent in the hippocampus and frontal cortex than in the cerebellum of human and mouse brain. Enoxacin and fenbufen each at a high concentration produced a moderate and slight inhibition of the [3H]muscimol binding, respectively, in the hippocampus and frontal cortex but not in the cerebellum. It would thus appear that the drug interaction between enoxacin and fenbufen on the gamma-aminobutyric acidA receptor in hippocampus and frontal cortex plays a role in inducing convulsions.

Animals↗
PubMed1991

[Studies on the chemical constituents of Dendrobium loddigesii rolfe].

According to IR, UV, MS and NMR spectra of the compounds isolated from the fresh stem of Dendrobium loddigesii Rolfe (a Chinese medicine), 3 constituents were identified. They are shihunidine, shihunine and dendrophenol (4,4'- dihydroxy-3,3',5-trimethoxybibenzyl). Chemical reactions showed that shihunidine was derived from shihunine during isolation. Shihunidine and shihunine were shown to be inhibitors of Na+, K+-ATPase of the rat kidney.

Animals↗
PubMed1991

Polyadenylation precedes splicing in vitro.

Vertebrate premessenger RNAs are usually spliced and polyadenylated. In vivo analysis of the relative kinetics of the two reactions is difficult. We have used in vitro processing systems to investigate the order of splicing and polyadenylation of chimeric precursor RNAs containing a single intron and a poly(A) site. Polyadenylated, but not spliced, intermediate RNA appeared first and reached a low steady-state level early during incubation, properties consistent with its being a reaction intermediate in the production of doubly-processed spliced and polyadenylated product RNA. The kinetics of polyadenylation suggested that polyadenylated RNA was the only intermediate in the production of doubly-processed RNA. Spliced, but not polyadenylated, RNA also appeared. This species, however, continued to accumulate during reaction, and could not be chased into product spliced and polyadenylated RNA. These data support a preferred order of reaction for 3' terminal introns and exons in which polyadenylation precedes splicing.

Adenoviridae↗
PubMed1991

Interpretation of patho-physiology by laboratory data (4). Cases of hypernutritional fatty liver.

Using blood chemistry data from 77 cases of hypernutritional fatty liver diagnosed in our gastroenterological clinic, an automated quantitative interpretation was formulated. The reliability of this interpretation was confirmed in view of the following points: 1) Comparison with the degree of fatty infiltration of the liver seen in biopsy specimens or ultrasonographic findings. 2) The high rate of coincidence, sensitivity and specificity among the results. 3) Localization of almost all the cases of fatty or non-fatty liver into circumscribed areas by the value of standard deviation index (SDI) of glutamic oxaloacetic transaminase (GOT) i.e. aspartate aminotransferase (AST) and cholinesterase (CHE), respectively. 4) Graphic display of data and interpretation of a representative case of acute hepatitis at specified stages, and the comparison of this interpretation with clinical diagnoses and course of the disease. Moreover, two possible mechanisms for the elevation of the CHE level were discussed.

Adult↗
PubMed1990

Structure of genomic DNA for rat platelet phospholipase A2.

A genomic DNA for rat platelet phospholipase A2 was isolated by screening a rat genomic library with oligonucleotide probes based on its published amino acid sequence. The rat platelet phospholipase A2 gene had a total length of about 2.5 kb and contained five exons and four introns. The intron-exon structure of the rate gene was similar to that of human non-pancreatic phospholipase A2.

Amino Acid Sequence↗
PubMed1990

Human seminal plasma Zn-alpha 2-glycoprotein: its purification and properties as compared with human plasma Zn-alpha 2-glycoprotein.

On the basis of the datum that the level of Zn-alpha 2-glycoprotein (Zn alpha 2gp) in human seminal plasma was about 6-times higher than that in adult serum, Zn alpha 2gp was purified from fresh human seminal plasma approx. 70-fold with 60% yield over seminal plasma by DEAE-Sephacel, Zn-chelate Sepharose 4B and DEAE-5PW column chromatographies. The molecular weight of seminal plasma Zn alpha 2gp was 50,000 on Superose column chromatography, and 40,500 and 41,500 on SDS-polyacrylamide gel electrophoresis in the absence and presence of beta-mercaptoethanol, respectively. Plasma Zn alpha 2gp is a glycoprotein, while the protein from seminal plasma does not contain carbohydrate. The amino acid sequence of the first 17 residues of seminal plasma Zn alpha 2gp was Glu-Asn-Gln-Asp-Gly-Asn-Tyr-Ser-Leu-Thr-Tyr-Ile-Tyr-Thr-Gly-Leu-Ser. This sequence was completely identical with the amino acid residues from Glu-2 to Ser-18 in the N-terminal amino acid sequence of plasma Zn alpha 2gp. These data suggest that both Zn alpha 2gps in plasma and seminal plasma may be expressed from one gene, but their posttranslational modifications are different.

Adult↗
PubMed1990

Partial characterization of insulin-like growth factor I in primary human lung cancers using immunohistochemical and receptor autoradiographic techniques.

We investigated primary human lung cancers resected surgically or obtained at autopsy. Included were squamous cell carcinoma (SQC) (five cases), adenocarcinoma (ADC) (six cases), large cell carcinoma (LCC) (four cases), and small cell carcinoma (SCC) (two cases). The objective of the study was to search for the presence of insulin-like growth factor I (IGF-I)-like immunoreactivity using immunohistochemical staining and for the localization of IGF-I binding sites, using in vitro quantitative receptor autoradiographic techniques. IGF-I-like immunostaining was present in all cases of SQC, ADC, and LCC, but not in cases of SCC. Strong immunostaining was observed in cases of SQC. On the other hand, ADC and LCC tissues showed a moderate or weak staining. Specific binding sites for IGF-I were present in all cases of SQC, ADC, LCC, and SCC examined. High densities of 125I-IGF-I binding sites were localized in cases of SQC and SCC. Low to high densities of the binding sites were found in LCC. Cases of ADC showed low densities of 125I-IGF-I binding sites. Specific binding obtained at a concentration of 80 pM 125I-IGF-I was competitively displaced by unlabeled IGF-I, with a 50% inhibitory concentration value of 1.84 +/- 0.31 x 10(-10) mol, whereas human insulin was much less potent in displacing the binding. This specificity profile is consistent with characteristics of IGF-I receptors. Scatchard analysis showed the presence of a single class of high affinity binding sites for IGF-I, with a Kd of approximately 1 nmol. Thus, the possibility that IGF-I may play a role in the growth of human lung cancers would have to be considered.

Adenocarcinoma↗
PubMed1990

Specific [125I]brain natriuretic peptide-26 binding sites in rat and pig kidneys.

Specific binding sites for porcine brain natriuretic peptide-26 (BNP-26), a member of the atrial natriuretic peptide family (ANPs), were investigated in the kidney by using receptor autoradiographic and membrane binding techniques with [125I]BNP-26. The binding sites were discretely localized in rat and porcine kidney areas corresponding anatomically to the glomeruli and inner medulla. There were no differences between the localization of [125I]BNP-26 and [125I]alpha-rat ANP binding sites in the kidney. [125I]BNP-26 binding to solubilized membranes from isolated glomeruli of the rat kidney was saturable, and a single class of high-affinity sites was labeled with a KD of 372 pM. The radioligand bound to two sites in solubilized inner medullary membranes of the rat, a low-affinity site with a KD of 30 nM, and a high-affinity site with a KD of 33 pM. The rank order of potency to inhibit binding was BNP-26 = alpha-rat ANP-(1-28) greater than atriopeptin III (ANP-(103-126)) much greater than atriopeptin I (ANP-(103-123)) greater than des-Cys105,Cys121- ANP-(104-126). Thus, [125I]BNP-26 presumably recognizes ANP receptors in the kidney. The possibility that BNP-26 regulates, as a circulating hormone, kidney functions by binding to ANP receptors would have to be considered.

Animals↗
PubMed1990

Neuropeptide Y (NPY) and peptide YY (PYY) receptors in rat brain.

1. Specific binding sites for neuropeptide Y (NPY) and peptide YY (PYY) were investigated in rat brain areas using quantitative receptor autoradiography with 125I-Bolton-Hunter NPY (125I-BH-NPY) and 125I-PYY, radioligands for PP-fold family peptides receptors. 2. There were no differences between localization of 125I-BH-NPY and 125I-PYY binding sites in the rat brain. High densities of the binding sites were present in the anterior olfactory nucleus, lateral septal nucleus, stratum radiatum of the hippocampus, posteromedial cortical amygdaloid nucleus, and area postrema. 3. In cold ligand-saturation experiments done in the presence of increasing concentrations of unlabeled NPY and PYY, 125I-BH-NPY and 125I-PYY binding to the stratum radiatum of the hippocampus, layer I of the somatosensory frontoparietal cortex, molecular layer of the cerebellum, and area postrema was single and of a high affinity. There was a significant difference between the affinities of 125I-BH-NPY (Kd = 0.96 nM) and 125I-PYY binding (Kd = 0.05 nM) to the molecular layer of the cerebellum. The binding of the two radioligands to the other areas examined had the same affinities. 4. When comparing the potency of unlabeled rat pancreatic polypeptide (rPP), a family peptide of NPY and PYY, to inhibit the binding to the areas examined, rPP displaced 125I-BH-NPY and 125I-PYY binding to the area postrema more potently than it did the binding to the stratum radiatum of the hippocampus, layer I of the somatosensory frontoparietal cortex, and molecular layer of the cerebellum. 5. Thus, the quantitative receptor autoradiographic method with 125I-BH-NPY and 125I-PYY revealed differences in binding characteristics of specific NPY and PYY binding sites in different areas of the rat brain. The results provide further evidence for the existence of multiple NPY-PYY receptors in the central nervous system.

Animals↗
PubMed1990

Alteration of atrial natriuretic peptide receptors in the choroid plexus of rats with induced or congenital hydrocephalus.

Specific binding sites for atrial natriuretic peptide (ANP) in the choroid plexus of rats with induced or congenital hydrocephalus were examined using in vitro quantitative receptor autoradiographic methods. The number of 125I-ANP binding sites in the choroid plexus of rats with kaolin-induced hydrocephalus was significantly higher as compared to findings in the control rats, whereas no differences in the binding affinity were observed 3 days and 3 weeks after the intracisternal injection of kaolin. Conversely, rats with congenital hydrocephalus (LEW-HYR and HTX rats) had a small number of binding sites for 125I-ANP in the choroid plexus, as compared to findings in the control rats. These alterations may relate to the pathophysiology of hydrocephalus. The possibility that atrial natriuretic peptide may be involved in the regulation of cerebrospinal fluid production in the choroid plexus must be considered.

Animals↗
PubMed1990

Structure-activity relationships of analogues of the wasp toxin philanthotoxin: non-competitive antagonists of quisqualate receptors.

Fifty-two analogues of the wasp toxin, philanthotoxin-433, have been synthesized and tested on a glutamatergic, nerve-muscle preparation from locust leg. Reduction in amplitude of the neurally-evoked muscle twitch was used to construct dose-inhibition relationships from which IC50S were estimated. The most active analogues were characterized by one or more of the following: increased hydrophobicity of aromatic and tyrosyl regions; an increased number of protonated groups in the polyamine region; a guanidinium instead of a spermine terminal amino moiety. The incorporation of a butyl side-group in the polyamine also enhanced potency. These results are explained on the basis of the known non-competitive antagonistic blockage by philanthotoxin-433 of the channel gated by postjunctional glutamate receptors when the channel is open.

Animals↗
PubMed1990

Localization and characterization of endothelin receptors in human gliomas: a growth factor?

Localization and characterization of endothelin receptors in surgical specimens of human gliomas (6 benign astrocytomas and 7 glioblastomas multiforme) and in normal human cortices were studied using quantitative receptor autoradiographic methods. Low numbers of [125I]endothelin-1 [( 125I]ET-1) binding sites were detected in the gray matter of the human frontal cortex, with little binding in the white matter. Conversely, relatively high numbers of [125I]ET-1 binding sites were homogeneously present in tissue sections derived from astrocytomas, whereas higher numbers of [125I]ET-1 binding sites were heterogeneously located on groups of cells with a pseudopalisading appearance and pleomorphic astrocytes in glioblastoma multiforme. Necrotic areas within the tissue sections derived from glioblastoma were devoid of binding. Binding of [125I]ET-1 to gliomas and normal gray matter was specific. Unlabeled ET-1 and its natural analogs (ET-2 and ET-3) inhibited the binding of [125I]ET-1 to these lesions in a concentration-dependent manner and with similar high potencies. Possibly related substances, such as ion channel regulators (omega-conotoxin, apamin, and tetrodotoxin), a Ca2+ channel blocker (nicardipine), and growth factors (epidermal growth factor and insulin-like growth factor I), did not affect the binding to tissue sections derived from gliomas or from normal frontal cortices. Scatchard analysis revealed the presence of a single class and high-affinity binding sites for endothelin in normal cortex and in gliomas. There was no significant difference in the binding affinities: dissociation constants (Kd) were 2.1 +/- 0.5 nM in 6 astrocytomas, 2.5 +/- 0.4 nM in 7 glioblastomas, and 1.4 and 1.5 nM in two normal cortices.(ABSTRACT TRUNCATED AT 250 WORDS)

Binding Sites↗