Biomedical subjects

N Sakamoto

Publications and source records attributed to N Sakamoto.

At least 235 records · Page 13Linked to original sources

PubMed1993

Intrahepatocellular localization of copper in Wilson's disease.

It is well known that excess copper plays a role in the pathogenesis of Wilson's disease; however, the hepatic copper contents, determined either histochemically or biochemically, are not always correlated with the activity of Wilson's disease. To better understand copper-induced cytotoxicity, intrahepatocellular localization of copper was studied in five patients with Wilson's disease. The liver specimens were obtained by biopsy to confirm the clinical diagnosis of Wilson's disease before treatment. Neither hepatic copper content nor histochemical copper deposits were correlated with any of the biochemical indices studied. Energy-dispersion X-ray microanalysis was done on the nuclei, lysosomes and lysosome-free cytoplasm of hepatocytes. Lysosomes had the highest Cu X-ray intensity but no correlation was shown between the lysosomal copper content and biochemical indices. The nucleus/lysosome-free cytoplasm ratio of the copper content was correlated with the serum levels of aminotransferases. These results suggest that the copper increasing gradient from the lysosome-free cytoplasm to the nucleus is associated with hepatocyte necrosis, and probably causes irreversible nuclear damage.

Adolescent↗

PubMed1993

Cuproproteins of hepatocyte lysosomes in normal and fatty liver.

The pathophysiological significance of cuproproteins in hepatocyte lysosomes was studied in 7 patients with structurally normal livers and 13 patients with fatty livers by energy-dispersion X-ray microanalysis. In most patients, in both groups, copper and sulfur coexisted in hepatocyte lysosomes. The correlation between copper and sulfur indicated that copper transfer between the cytosol and lysosomes was mediated by a cuproprotein. The copper indices of the lysosomal proteins and transfer proteins were high in some fatty livers. These observations suggest that cuproproteins in hepatocytes are not necessarily pathological, but are present in greater amounts in some fatty livers, probably because of impaired bile drainage.

Adult↗

PubMed1993

Glomerular localization of thrombomodulin in human glomerulonephritis.

BACKGROUND: Thrombomodulin (TM), a glycoprotein expressed on the surface of endothelial cells, transforms protein C into a potent anticoagulant by binding thrombin. TM may be an important regulator of intraglomerular coagulation because functional TM activity was demonstrated in glomeruli isolated from normal human and rat kidneys. The role of TM in glomerulonephritis is unknown. EXPERIMENTAL DESIGN: Sections from 4 normal human kidneys and from kidneys of 100 patients with various forms of glomerulonephritis were studied by light and transmission electron microscopy, and by light and electron immunohistochemical techniques using polyclonal antibodies to recombinant human TM, and monoclonal antibodies to the membrane attack complex of the complement system. The expression of TM was graded from 0 to 4 according to the intensity and extent of the distribution, and the results were compared with the clinicopathologic findings. RESULTS: In normal glomeruli and in glomeruli with minimal abnormalities, a small amount of TM was localized at the vascular pole only (grade 0-1). In membranoproliferative glomerulonephritis and lupus glomerulonephritis, the amount of TM found on the plasma membrane of endothelial cells was significantly increased (grades 2 to 4). The expression of TM was directly correlated with proteinuria (p < 0.001), glomerular hypercellularity (p < 0.01), and number of subendothelial immune deposits (p < 0.01). In contrast, in other forms of glomerular diseases, TM was not increased and no correlation was found with the clinicopathologic parameters. CONCLUSIONS: In membranoproliferative glomerulonephritis and lupus glomerulonephritis, the amount of TM expressed by the plasma membranes of glomerular endothelial cells is increased, and this finding is a marker of disease activity. The significance of an increased expression of an endothelial anticoagulant glycoprotein in diseases characterized by pathologic intraglomerular coagulation is unknown, and requires further studies.

Fluorescent Antibody Technique↗

PubMed1993

[Carbohydrate metabolism].

This review summarizes progress in glycosylation research of relevance to atherosclerosis. Glucose reacts in vivo with cellular proteins nonenzymatically and forms Amadori products. The Amadori products proceed very slowly to undergo a number of further dehydration and rearrangement to form advanced glycosylation end products (AGE). The AGE moiety are characterized by being brown, fluorescent chromophores that can cross-rink proteins. In contrast Amadori products, AGE are irreversible and accumulate on long-lived proteins (eg, collagen, enzyme, lens crystallins) for many years. AGE proteins can modify lipoproteins fibrinogen, collagen and DNA. AGE protein receptor is identified on macrophages. AGE may accelerate development of atherosclerosis by various manner.

Aging↗

PubMed1993

Mesangial proliferative glomerulonephritis induced in rats by a lentil lectin and its antibodies.

Experimental glomerulonephritis was induced in rats to investigate the consequence of the antigen-antibody interaction on the surface of glomerular endothelial cells (GENs). A lectin, Lens culinaris hemoagglutinin (LCH), was first planted in the left kidney by isolated perfusion of a left kidney, and then the circulation was reestablished. Rabbit anti-LCH antibodies were injected from the tail vein 3 minutes after the recirculation of the left kidney, and acute glomerulonephritis ensued. Fifteen minutes after the injection, rabbit immunoglobulin G (IgG), rat C3, and LCH were observed exclusively on the surface of GENs. Accumulation of platelets was prominent. Three hours later, the immune deposits were seen in the subendothelial space, and the polymorphonuclear cells were the dominant infiltrate in the glomeruli. Up to the seventh day, immune deposits were seen in the subendothelial space, and the widening of this area was increasingly observed. Fourteen days later, immune deposits containing rat IgG were observed in the subepithelial area, but they were only occasionally seen in the subendothelial space and in the mesangial area. No crescent formation was seen at day 14, but the mesangial area was expanded, with an increased number of cells. The number of nuclei in the cross-section of a glomerulus increased after the induction of glomerulonephritis, but the number of leukocyte common antigen-positive cells (infiltrating cells) decreased gradually from day 4 to day 14. The staining of Thy-1.1, a marker of mesangial cell, was markedly enlarged in the glomerulus at day 14. These data suggest that mesangial proliferative glomerulonephritis can be induced by the antigen-antibody interaction on the surface of GENs.

Animals↗

PubMed1993

[A case of advanced gastric cancer responding to an FAP (5-FU, ADM, platinum compounds) combined chemotherapy].

An experience with an advanced gastric cancer patient with metastases to bilateral breasts, uterus, abdominal lymph nodes, bilateral axillary and supraclavicular lymph nodes, and bone marrow, responded extremely well to an FAP combined chemotherapy as reported here. The patients received four courses of 5-FU (370 mg/m2/day, for five days, continuous infusion), ADM (30 mg/m2 on day 1, i.v.) and CDDP (55 mg/m2 on day 1, i.v.) every 3 weeks in our hospital. This was followed by 7 months of outpatient therapy with 5-FU (550 mg/m2 on day 1, i.v.), ADM (30 mg/m2 on day 1, i.v.) and CBDCA (330 mg/m2 on day 1, i.v.) for every 4 weeks. The complete remission of the primary and metastatic lesions, that was confirmed by the histological examinations, was obtained after 10 months since the initial treatment started. The toxicity was generally moderate, however, the alopecia was severe. The patient has been living for 6 months without any signs of the recurrence after the complete remission obtained.

Adenocarcinoma↗

PubMed1992

Delta-thalassemia caused by disruption of the site for an erythroid-specific transcription factor, GATA-1, in the delta-globin gene promoter.

Delta-thalassemia is a complex group of inherited disorders of globin genes characterized by impaired synthesis of the delta-globin chain. The T-C substitution was detected at position -77 of the delta-globin gene isolated from three independent Japanese individuals who were homozygotes for delta-thalassemia. To elucidate the significance of the mutation in delta-globin gene expression, we investigated the genotype of three delta-thalassemia homozygotes and 58 normal individuals using dot blot hybridization of the polymerase chain reaction (PCR)-amplified DNA. The mutation was observed in six alleles of three homozygotes, while no mutation was detected in 116 alleles of normal individuals, thereby indicating the close association of this mutation with the thalassemia phenotype. Since the mutation (TTATCT-TCATCT) is located within the inverted binding motif of GATA-1 (T or A-G-A-T-A-G or A), an erythroid cell-specific transcription factor, we did gel retardation assays using nuclear extracts from the erythroid cells. We found that GATA-1 binds the oligonucleotide spanning positions -61 to -90, but does not bind to the oligonucleotide with the mutation at position -77. Competition gel retardation assays showed that GATA-1 binding can be competed out by the fragment with the GATA-1 motif, but not with the mutant oligonucleotide. Analysis of the transient expression of the CAT gene linked to the delta-globin gene promoter region demonstrated that the construct with the mutant promoter region was expressed about 20-fold less compared with the normal one. Thus, the mutation at position -77 impairs delta-globin gene expression by abolishing GATA-1 binding to the AGATAA sequence of the promoter region of the delta-globin gene. This provides a good example of involvement of tissue-specific transacting factors in the molecular pathogenesis of hereditary diseases.

Base Sequence↗

PubMed1992

Cytochrome b558, a component of the phagocyte NADPH oxidase, is a flavoprotein.

Cytochrome b558 is the only membrane component of the phagocyte O2(-)-producing NADPH oxidase. The O2- production by the oxidase reconstituted in vitro with the crude membrane fraction is enhanced several-fold by addition of FAD, whereas that with the partially purified cytochrome is completely dependent on exogenous FAD, suggesting that FAD acts through the membrane component, cytochrome b558. The alignments of the amino acid sequence of the large subunit of the cytochrome (gp91-phox) with those of previously characterized flavoproteins reveal that the middle and C-terminal portions of gp91-phox are likely to be FAD- and NADPH-binding domains, respectively. Cytochrome b558, thus, appears to be a flavoprotein with an NADPH-binding site, of the NADPH oxidase.

Amino Acid Sequence↗

PubMed1992

Molecular structure of the C beta catalytic subunit of rat cAMP-dependent protein kinase and differential expression of C alpha and C beta isoforms in rat tissues and cultured cells.

A full-length cDNA clone encoding the C beta catalytic subunit of cAMP-dependent protein kinase (PKA) was isolated from a rat brain cDNA library. A 1.1 kb cDNA containing the entire coding region encodes for a protein of 351 amino acids that shows more than 95% sequence homology to the C beta subunits in mouse, bovine and human. Northern blot analysis showed distinct patterns of C alpha and C beta mRNA expression in the brain and various peripheral tissues. The C alpha mRNA was widespread and highly expressed in brain, heart, adrenal gland, testis, lung, kidney, spleen and liver, whereas the C beta mRNA was unevenly expressed in the brain and adrenal gland and in much lesser amounts in other tissues. The C alpha mRNA was evenly distributed and highly expressed through various regions of the brain, while the C beta mRNA was expressed in lesser amounts and was unevenly distributed. In neuronal and glial cultured cells, C alpha mRNA was also predominantly expressed but C beta mRNA was undetectable. The differential distribution between the C subunit isoforms of PKA suggests that individual subunits are involved in specialized functions.

Amino Acid Sequence↗

PubMed1992

Gly145 to Arg substitution in HBs antigen of immune escape mutant of hepatitis B virus.

A Japanese child born to an HBeAg-positive carrier mother received anti-HBs immunoglobulins and a plasma-derived HBs vaccine with a poor anti-HBs-antibody response. The child, who is now 3 years old, is presently suffering from chronic hepatitis with unusual serological findings that are positive for HBsAg, anti-HBs and HBeAg, since being infected with a measles virus at 12 months of age. The nucleotide sequences of the S region of HBV DNA obtained from the patient, the mother and an HBeAg-positive brother were completely identical except for one nucleotide at position 587 (mother and brother: guanosine, patient: adenosine), giving an amino acid change: Gly - greater than Arg at position 145 of the major HBs protein.

Amino Acid Sequence↗

PubMed1992

Inhibition of development of Kaposi's sarcoma-related lesions by a bacterial cell wall complex.

In vitro and in vivo model systems for the study of human immunodeficiency virus (HIV)-associated Kaposi's sarcoma (KS) were used to evaluate compounds for their potential as therapeutic agents. A sulfated polysaccharide-peptidoglycan compound (SP-PG) produced by bacteria controlled the in vitro growth of acquired immunodeficiency syndrome (AIDS)-associated, KS-derived spindle-shaped cells (AIDS-KS cells) at noncytotoxic concentrations. Angiogenesis induced by AIDS-KS cells in the chicken chorioallantoic membrane assay was blocked by SP-PG, which also inhibited the vascular hyperpermeability response and the angiogenesis associated with the induction of KS-like lesions that develop after subcutaneous inoculation of AIDS-KS cells into nude mice. Suramin, pentosan polysulfate, and interferon alpha, which are currently in use for therapy of KS, were either less effective than SP-PG or much more cytotoxic, or both.

Acquired Immunodeficiency Syndrome↗

PubMed1992

Role of brain histamine H1- and H2-receptors in neostigmine-induced hyperglycemia in rats.

We previously reported that when neostigmine, an inhibitor of acetylcholine esterase, was injected into the third cerebral ventricle, the concentration of hepatic venous plasma glucose was increased via central muscarinic receptors in anesthetized rats. To determine whether brain histamine receptors are involved in cholinergic system transmission with regard to central nervous system (CNS)-mediated glucoregulation, we examined the effects of the H1 receptor antagonist pyrilamine and the H2 receptor antagonist ranitidine on neostigmine-induced hyperglycemia in anesthetized rats. The injection of pyrilamine (5 x 10(-9)-5 x 10(-7) mol) into the third cerebral ventricle suppressed hyperglycemia induced by intraventricular injection of neostigmine (1 x 10(-9) mol) in a dose-dependent manner. Injection of ranitidine (5 x 10(-9)-5 x 10(-7) mol) into the third cerebral ventricle did not suppress the hyperglycemia induced by neostigmine, but enhanced it in a dose-dependent manner. These findings suggest that neostigmine-induced CNS-mediated hyperglycemia is transmitted by not only brain cholinergic muscarinic receptors but also in part by histamine H1 receptors.

Animals↗

PubMed1992

Effects of adrenergic blockers on central nervous system-mediated hyperglycemia in fed rats.

We studied the effect of adrenergic blockade on hepatic venous hyperglycemia and the activation of a hepatic glycogenolytic enzyme, phosphorylase-a, in response to cerebral cholinergic activation. Neostigmine was injected into the third cerebral ventricle of bilaterally adrenodemedullectomized (ADMX) rats, while somatostatin and insulin were administered intravenously. Hepatic venous plasma glucose concentrations and hepatic phosphorylase-a activity were measured. Intracerebroventricular injection of neostigmine (5 x 10(-8) mol) caused increases in hepatic venous glucose concentrations and hepatic phosphorylase-a activity. Both of these changes were prevented by intraperitoneal (IB) pretreatment with phentolamine (5 x 10(-7), 1 x 10(-6) mol) without the intervention of insulin secretion, but not by pretreatment with the alpha-adrenoreceptor antagonist phenoxybenzamine (1 x 10(-6) mol), the beta-adrenoreceptor antagonist propranolol (1 x 10(-6) mol), the alpha 1-antagonists prazosin or bunazosin (1 x 10(-6) mol), the alpha 2-antagonist yohimbine (1 x 10(-6) mol), or prazosin (5 x 10(-7) mol) plus yohimbine (5 x 10(-7) mol). These results suggest that phentolamine prevented brain-mediated hepatic glycogenolysis by a mechanism that may not be classified pharmacologically as involving either alpha 1- or alpha 2-receptors.

Adrenalectomy↗

PubMed1992

Nonspecific granulomatous prostatitis.

Nonspecific granulomatous prostatitis is a relatively rare disorder of the prostate. We encountered 4 cases of this type of chronic inflammation, including 1 case of xanthogranulomatous prostatitis. In all cases the diagnosis was made by histologic examination of specimens obtained by transurethral resection, retropubic prostatectomy, or transrectal needle biopsy. Echography revealed a hypoechoic lesion in the case of xanthogranulomatous prostatitis, while the other cases showed no specific findings except for the associated adenomas. The major symptoms were frequency and dysuria caused by urinary tract infection or benign prostatic hyperplasia associated with the granulomatous prostatitis.

Aged↗

PubMed1992

Influence of sympatho-adrenal system on insulin sensitivity using the euglycemic clamp technique.

The aim of the present study was to further investigate the role of the adrenergic system on insulin action using the euglycemic clamp technique. Whole-body glucose metabolism (GM) was calculated as the glucose infusion rate for maintaining euglycemia under insulin infusion and used as an indicator of insulin sensitivity. Euglycemic clamps were performed in adrenodemedullated, epinephrine-treated, phentolamine-treated (alpha-blockade), propranolol-treated (beta-blockade), and epinephrine plus phentolamine and/or propranolol-treated rats. The following results were obtained at an insulin level of approximately 80 mU/l. GM in adrenodemedullated rats (13.97 +/- 0.98 mg/kg/min) was significantly higher than that of the control rats (10.26 +/- 0.50 mg/kg/min, P less than 0.01). GM in epinephrine-treated rats (1.7 mg/kg body weight/h) was 2.12 +/- 0.49 mg/kg/min (P less than 0.001 vs. control). Dose-response curves for phentolamine and propranolol established maximally effective doses (3.0 mg and 12 mg/kg body weight/h, respectively). Using these doses, GM in epinephrine plus phentolamine-treated rats (4.90 +/- 0.39 mg/kg/min) was significantly higher than that of epinephrine alone and GM in epinephrine and propranolol-treated rats (4.49 +/- 0.47 mg/kg/min) was also significantly higher than that of the epinephrine alone. GM in the epinephrine plus both propranolol and phentolamine (5.94 +/- 0.45 mg/kg/min) was significantly higher than that of the epinephrine alone, but not different from either treatment alone and was not additive. Neither phentolamine alone (9.48 +/- 1.45 mg/kg/min), propranolol alone (10.36 +/- 0.55 mg/kg/min) or the combination of blockades (11.14 +/- 0.65 mg/kg/min) had any effect on GM.(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenal Medulla↗

PubMed1992

Establishment and characterization of doxorubicin-resistant human bladder cancer cell line, KK47/ADM.

A human bladder cancer cell line resistant to doxorubicin, KK47/ADM has been established in vitro by exposing KK47 parent cells to progressively higher concentrations of the drug over a period of 16 months. The KK47/ADM was 271 times more resistant to doxorubicin than the KK47 parent. The KK47/ADM exhibited cross-resistance to doxorubicin derivatives (pirarubicin, epirubicin), vinca alkaloids (vinblastine, vincristine) and etoposide, but not to cisplatin, carboplatin, mitomycin C, peplomycin and methotrexate. Unlike the KK47 parent, about 70% of the KK47/ADM cells showed a positive reaction with monoclonal antibody against P-glycoprotein, MRK16. Uptake and efflux studies with [14C]doxorubicin indicated that the resistance exhibited by the KK47/ADM line was mainly due to a lower accumulation of the drug caused by an increased active efflux, and these were reversed in the presence of verapamil. Although verapamil enhanced doxorubicin sensitivity of KK47/ADM, a complete overcoming of the resistance could not be obtained. These two lines with different chemosensitivity are thus considered to be a useful model for developing new chemotherapeutic strategies against multidrug resistant bladder cancer.

ATP Binding Cassette Transporter, Subfamily B, Mem↗

PubMed1992

Urinary bladder carcinoma with a neoplastic squamous component: a mapping study of 31 cases.

A mapping study of cystectomy specimens in three cases of pure squamous cell carcinoma and 28 cases with transitional cell carcinoma with squamous differentiation is described, with an emphasis on the histogenesis of pure squamous cell carcinoma. Two of the three cases of pure squamous cell carcinoma had extensive benign keratinizing mucosa and an atypical squamous metaplastic mucosa contiguous with the tumour. These pure squamous cell carcinomas seemed to be derived from the squamous metaplasia. On the other hand, in all except one of the cases of transitional cell carcinoma with squamous differentiation, there was neither benign keratinizing nor atypical squamous metaplastic mucosa in the bladder. The quantitative amounts of both the transitional cell and squamous components differed from case to case in 28 cases with transitional cell carcinoma with squamous differentiation. Five of the 28 had a tumour composed predominantly of a squamous component with minute transitional cell components at the margin. In another two cases, transitional carcinoma in situ or satellite tumours of transitional cells were present adjacent to the main tumour which was composed of squamous cell carcinoma alone. We think these seven tumours originated as a result of extensive squamous differentiation in the transitional cell carcinomas. These features may indicate two forms of histogenesis of pure squamous cell carcinoma. The first is malignant transformation on the basis of squamous metaplasia of the bladder mucosa and the second is extensive squamous differentiation in a pre-existing transitional cell carcinoma.

Aged↗

PubMed1992

Mechanism of intrahippocampal neostigmine-induced hyperglycemia in fed rats.

We previously reported that the injection of neostigmine, an acetylcholine esterase inhibitor, into the dorsal hippocampus produced hepatic venous plasma hyperglycemia associated with an increase of epinephrine and glucagon in anesthetized fed rats. To evaluate the relative contribution of these glucoregulatory hormones and the nervous system to the net hyperglycemic response, we unilaterally injected neostigmine (5 x 10(-8) mol) into the dorsal hippocampus in the following groups of rats: intact rats with bilateral adrenalectomy to eliminate the action of epinephrine, and rats receiving a constant infusion of somatostatin and insulin to prevent the glucagon response and to maintain the basal insulin level. Hepatic venous plasma levels of glucose, immunoreactive glucagon, immunoreactive insulin, epinephrine, and norepinephrine were determined. The area under the glucose curve during the 120-min period following the injection of neostigmine was compared between groups. The areas under the glucose curve for rats receiving somatostatin and insulin, adrenalectomy rats, and adrenalectomy rats receiving somatostatin and insulin were, respectively, 82, 31, and 61% of that for intact rats. The fashion of hippocampal stimulated hyperglycemia with neostigmine was similar to that after injection of neostigmine into the third cerebral ventricle. Therefore, we investigated hyperglycemia in rats with lesions of ventromedial hypothalamus and found that the response to hippocampal neostigmine was significantly inhibited by the hypothalamic lesion. These findings suggest that the glucoregulatory hippocampal activity evoked by neostigmine may be transmitted to peripheral organs via the ventromedial hypothalamus.

Animals↗