Biomedical subjects

N Okada

Publications and source records attributed to N Okada.

At least 19 recordsLinked to original sources

PubMed1992

Specific cytolysis of HIV-infected cells by lymphocytes armed with bifunctional antibodies.

The Fab' fragment of a monoclonal antibody (mAb) directed to CD3 (a portion of the T cell receptor) and the Fab' or F(ab')2 fragment of an mAb to HIV were combined to generate bifunctional antibody (BFA) consisting of antiCD3-Fab' conjugated with anti-HIV-Fab' (Fab'/Fab') or antiCD3-Fab' conjugated with anti-HIV-F(ab')2 (Fab'/F(ab')2), respectively. In the presence of these BFA, HIV-infected target cells were cytolysed by peripheral blood lymphocytes. Treatment of lymphocytes with Fab'/F(ab')2 type BFA rendered the lymphocytes significantly cytotoxic to HIV-infected target cells. Since BFA-armed lymphocytes can react on HIV-infected cells regardless of histocompatibility, lymphocytes from healthy donors could be armed with BFA for treatment of HIV-infected patients including those who do not exhibit histocompatibility with the lymphocyte donor.

Antibodies, Monoclonal↗

PubMed1992

Complement regulatory proteins at the feto-maternal interface during human placental development: distribution of CD59 by comparison with membrane cofactor protein (CD46) and decay accelerating factor (CD55).

The complement (C) regulatory proteins decay-accelerating factor (DAF, CD55) and membrane cofactor protein (MCP, CD46), which control C3 convertases, together with CD59, an inhibitor of the membrane attack complex (MAC), were found to be present in the developing human placenta from at least 6 weeks of gestation until term. Immunostaining revealed differences in the distribution of these proteins on the fetally derived trophoblast epithelium, especially in early placentae which contain trophoblast populations of diverse proliferative potential and differentiation status. Expression of all three proteins occurred on the terminally differentiated syncytiotrophoblast epithelium covering chorionic villi and which is in direct contact with maternal blood. CD59 was also expressed on the underlying villous cytotrophoblast cells and on their extra-villous derivatives. These two populations showed differential expression of the C3 convertase regulators. Villous cytotrophoblast cells expressed MCP but were largely devoid of DAF. Proliferation of this population to generate extra-villous cytotrophoblast cell columns was associated with both an increase in DAF expression and a decrease in MCP expression. Throughout placental development, expression of DAF appeared to be lower than that of MCP and CD59 as assessed by solid-phase binding assays on isolated trophoblast membranes. Early placentae were also found to contain both DAF+ and DAF- chorionic villi. Conversely, expression of CD59 appeared comparatively high and transcripts for CD59 were found to be much more abundant than those for DAF in purified trophoblast cells. C regulatory proteins appear to play an important role throughout gestation in protecting the fetally derived human conceptus from maternal C. The differential expression patterns of the proteins on trophoblast may reflect differences in requirement for specific functional activities at different locations within the placenta.

Antigens, CD↗

PubMed1992

Species-specific restriction of complement by HRF20 (CD59) generated by cDNA transfection.

The 20-kDa homologous restriction factor (HRF20, CD59) is a phosphatidyl inositol-anchored membrane glycoprotein that inhibits the formation of human complement membrane attack complexes. The cDNA of HRF20 was transfected into Chinese hamster ovary (CHO) cells resulting in expression of human HRF20 protein on the cell surface anchored via glycosylphosphatidyl inositol. The transfected CHO cells were resistant to human complement-mediated cell killing. However, the cells remained sensitive to rat and guinea pig complement. Therefore, species specificity between HRF20 and complement is maintained in HRF20 generated on the CHO cells following transfection with HRF20 cDNA.

Animals↗

PubMed1992

Paroxysmal nocturnal hemoglobinuria due to hereditary nucleotide deletion in the HRF20 (CD59) gene.

HRF20 (CD59) is a membrane glycoprotein which protects cells from the membrane attack reaction of homologous complement. A patient who is completely deficient in HRF20 expression and is suffering from paroxysmal nocturnal hemoglobinuria (PNH) was studied. His parents are cousins and both have decreased HRF20 expression, suggesting that the deficiency is genetic. We established a cultured cell line (NCU1) which is HRF20 deficient from the patient's lymphocytes by Epstein-Barr-virus (EBV) infection. Northern blot analysis revealed HRF20 mRNA signals, indicating that HRF20 mRNA were transcribed. HRF20 cDNA was amplified by the polymerase chain reaction (PCR) method. Sequencing of the cDNA from the NCU1 showed two single-base deletions at amino acid 16 and 96 from the N terminus of the mature protein. Deletion in the genomic DNA of peripheral blood lymphocytes was confirmed by the DNA sequence of an HRF20 open reading frame containing amino acid 16. Furthermore, the patient's parents and sister possessed both intact and deleted genomic HRF20 DNA while his brother's DNA was intact. These findings demonstrate that the HRF20 deficiency was genomic in origin, and that complete deletion was brought about by a homozygous abnormality in the HRF20 gene. The base deletion caused a codon frame shift resulting in failure to produce intact HRF20 protein in the patient.

Antigens, CD↗

PubMed1992

A two-colour flowcytometric study of cell kinetics and differentiation of human keratinocytes in culture.

Double histochemical staining followed by flow cytometric analysis was performed to determine whether involucrin synthesis is associated with a particular phase of the cell cycle. In low-calcium medium (0.1 mM) monolayer cultures the expression of involucrin was confined to about 8% of the total cell populations. When the concentration of calcium was increased to 1.8 mM, the percentage increased and the distribution pattern of the cell cycle changed. The addition of retinoic acid at concentrations in the range 10(-8) M to 10(-6) M to a high-calcium medium induced a further increase. The greatest increase in involucrin expression (up to five-fold) occurred in both the G1/G0 and G2 + M phases, while S phase cells showed a two-fold increase. The results indicate that involucrin synthesis is induced by retinoic acid, which occurs at any stage of the cell cycle, even in the S phase.

Calcium↗

PubMed1992

Malignant melanomas of the oral cavity: heterogeneity of pathological and clinical features.

Data on 35 patients with oral malignant melanomas were pooled and the pathological features and the clinical course were examined in detail. Of these 35 cases, 27 (77.1%) showed a two-phase growth pattern, with both a vertical and a radial growth phase. Moreover, these 27 cases were classified into three subtypes according to gross features of the vertical growth phase; nodular, flat elevated and ulcerated types. Almost two-thirds of the cases were of the melanotic type. Malignant melanomas without a radial growth phase were found in 8 instances, all of which showed a nodular growth pattern, 1 being of melanotic type and 7 amelanotic. Mean latent insidious periods were evaluated for the cases with different growth phases. Cases with a radical growth phase exhibited the longest mean latent period (35.7 months), and a median survival time of 23.5 months. Cases without a radial growth phase showed a short mean latent period (2.1 months), and a median survival time of 7.5 months. The thickness of invasion ranged from 2 to 9 mm. Although 77.1% of the cases depicted similar pathological patterns to acral lentiginous melanomas of the skin, oral malignant melanomas demonstrated heterogeneity in morphological features, developmental process and biological behaviour. The histogenesis of oral melanomas is briefly discussed.

Adult↗

PubMed1992

Terminal deletion of the short arm of chromosome 3.

A boy with growth and mental retardation, flat occiput, high and broad forehead, blepharoptosis, narrow palpebral fissures, low set, malformed ears, short neck, anal atresia, deep sacral dimple is reported. High-resolution banding analysis showed terminal deletion of the short arm of chromosome 3 (46,XY,del(3)(p25.3)). Deletions of the short arm of chromosome 3 are relatively rare. The clinical features of the patient are compared with those of 19 previously reported cases.

Abnormalities, Multiple↗

PubMed1992

CD59 (homologous restriction factor 20), a plasma membrane protein that protects against complement C5b-9 attack, in human atherosclerotic lesions.

Blood cells express a cell membrane protein, termed homologous restriction factor 20 (HRF20) and identical to CD59, that can inhibit complement C5b-9 insertion into their membranes. In this report, we investigated by immunohistochemistry whether CD59 was present on cells in human atherosclerotic lesions since membranous C5b-9(m) has been found in lesions. Using a monoclonal anti-CD59 antibody, a cellular CD59 staining pattern was apparent in nearly all lesion specimens. CD59 stain co-localised with macrophage (CD14), T lymphocyte (CD7), endothelial cell (anti-factor VIII related antigen) and smooth muscle cell cytoskeletal-specific antigens (anti-alpha actin and muscle myosin). Endothelial cells always exhibited a more intense stain than the other cell types. CD59 antigen was not localised to any one area of the lesions. Usually CD59-positive cells occurred in clusters rather than as randomly spaced individual cells. CD59 did not stain all cells of the lesion and in particular did not appear to stain all smooth muscle cells. Areas of CD59-negative cells were sometimes observed to exhibit a cellular C5b-9 staining pattern. C5b-9 deposits were also observed in CD59-positive regions. Normal saphenous vein stained strongly for CD59 at the endothelial lining and weakly in the media. Capillaries in atherosclerotic intima always stained strongly for CD59. We conclude that HRF20 is constitutively expressed on endothelium and is under regulatory control in smooth muscle cells. Cellular C5b-9 attack in atherosclerotic lesions is therefore most likely to occur on smooth muscle cells.

Actins↗

PubMed1992

Abnormal molecular weight profile of urinary protein in rats with streptozotocin-induced diabetes.

A quantitative analysis of the molecular weight (MW) profile of urinary protein by SDS-PAGE was performed in streptozotocin (STZ)-injected, non-ketotic diabetic rats (DM group), diabetic rats receiving dipyridamole (DM-DIP group), normal rats (C group) and STZ-injected rats with near-normal glycemia due to insulin treatment (DM-INSULIN group). In the DM group, decrease of a small MW protein (SMWP) (MW 19.5 k) was found at 2.5 weeks, and an increase of larger MW proteins (LMWP) (MW 68 [albumin], 55 and 29 k) together with a decrease of SMWPs (MW 19.5 and 15 k) was found at 15 weeks, as compared to the C group: the MW profile of urinary protein in the DM-INSULIN and C groups was indistinguishable. At 15 weeks, creatinine clearance (Ccr) was significantly depressed and an increase in the mesangial matrix with electron dense deposits was evident in the DM group. The urinary protein abnormalities were partially corrected and the reduction of Ccr was absent in the DM-DIP group with no effect on glomerular morphology. STZ-induced diabetes in rats is accompanied by a reduction of urinary SMWP, and a subsequent increase of LMWP and depression of Ccr: dipyridamole ameliorates urinary protein abnormalities and prevents the reduction of Ccr.

Animals↗

PubMed1992

Computed tomography and ultrasonography in submandibular tumours.

The value of computed tomography (CT) and ultrasound (US) for assessing submandibular tumours has been assessed. Thirty-five patients with 23 benign submandibular gland tumours and 12 malignant tumours have been investigated. In 33/35 patients, 18 plain CT (PCT), 19 CT sialography (CTS), and eight intravenous contrast-enhanced CT (CECT) procedures were performed. PCT did not allow clear delineation of 78% of the lesions, due to the similar density of the tumour and normal submandibular gland parenchyma. The tumours were easily recognized as low-echogenic or low-density masses by US, CTS and CECT. Benign lesions were usually sharply demarcated and had smooth borders on US, CTS and CECT. In addition, lobulation was often recognized in pleomorphic adenomas. Malignant tumours were poorly defined with irregular borders in 11/12 cases on US, CTS and CECT. CECT was superior to PCT and CTS in providing images of the tumour and its involvement of adjacent structures. It was concluded that US is the most useful primary examination method for submandibular tumours, while CECT provides the best evaluation of extension to the surrounding structures and/or adjacent lymph nodes. CTS seems to be unnecessary, if a submandibular tumour can be visualized by US and CECT.

Adenoma, Pleomorphic↗

PubMed1992

Differential effects of body weight, hyperinsulinemia and oral glucose load on serum C-peptide/insulin molar ratio.

Serum C-peptide immunoreactivity (CPR)/immunoreactive insulin (IRI) molar ratio was determined in 136 subjects without renal, hepatic and thyroid disorders, at fasting, and during the initial period of 75 g-oral glucose tolerance test. The subjects were divided into 4 groups based on their body weight and age; Group A, young (< 55 years) and normal body weight (body mass index [BMI, kg/m2] < or = 25) subjects; Group B, young and overweight (BMI > 25) subjects; Group C, aged (> or = 55 years) and normal body weight (BMI < or = 25) subjects; Group D, aged and overweight subjects. Fasting CPR/IRI ratio and absolute CPR level negatively correlated in Groups B and D but not in A and C. After oral glucose load with elevation of insulin, CPR/IRI ratio invariably declined in all groups and significant negative correlation between CPR/IRI and CPR was found in Groups A, B and D but not in C. Slope of the regression lines obtained for correlation between CPR/IRI ratio and CPR were significantly steeper at fasting compared to the post-stimulation phase. CPR/IRI ratio is affected by hyperinsulinemia and oral glucose load but not by obesity alone. Assuming that CPR/IRI ratio reflects hepatic extraction of insulin, the insulin clearance at fasting is progressively reduced with increasing insulin secretion in overweight subjects: failure to detect such phenomenon in normal body weight subjects may be due to a narrower CPR range in this population. Insulin metabolism at fasting and during glucose stimulation is likely to be regulated by distinct factors.

Aged↗

PubMed1992

Decreased expression of the membrane inhibitor of complement-mediated cytolysis CD59 on T-lymphocytes of HIV-infected patients.

OBJECTIVE: To study the expression of the membrane inhibitor of complement-mediated cytolysis, CD59, on peripheral blood mononuclear cells (PBMC) from HIV-infected individuals. METHODS: CD59 membrane expression was investigated by double immunofluorescent staining on purified PBMC from HIV-infected patients and seronegative controls. RESULTS: CD59 expression was decreased on peripheral blood T-lymphocytes from HIV-infected patients. Decreased expression of CD59 antigen did not correlate with clinical stage of disease. Low CD59 expression on T-lymphocytes was mediated by several mechanisms, including: (1) decrease in number of CD4+ cells which normally express high amounts of the antigen; (2) relative increase in CD8+ cells, more specifically in CD8+ CD57+ cells expressing a low density of the antigen; (3) loss of or decreased CD59 expression on a subpopulation of CD3+ belonging either to the CD4+ or to the CD8+ subset. Decreased CD59 expression was consistently observed on CD8+ lymphocytes. CD59 expression was normal on patient red blood cells, monocytes and B-lymphocytes. CONCLUSIONS: HIV infection is associated with a T-cell-specific defect in CD59 membrane expression. Decreased CD59 expression may result in increased susceptibility of T-lymphocytes from HIV-infected patients to complement-mediated lysis.

Antigens, CD↗

PubMed1992

Histopathological development of gastric tumors induced by N-methyl-N'-nitro-N-nitrosoguanidine in rats.

The development of carcinoma was examined in male Wistar rats (n = 120) exposed to N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) in the drinking water (83 micrograms/ml) for 16 weeks. After MNNG administration, rats were investigated by endoscopic observation, visualization of microvascular structure, and estimation of lectin binding sites. Changes of bile reflux to the stomach was observed endoscopically at 24 weeks as well as the development of gastric mucosal erosions. Protruding and expansive ulcerating carcinomas developed at 36 weeks and had a microvascular pattern similar to that of human adenocarcinoma. Estimation of lectin binding site and pattern was useful to evaluate the malignant potential of cell proliferation. We postulate that endoscopic observation is valuable in investigating the development of gastric carcinoma, and microvascular structure and lectin binding pattern may be useful to demonstrate the mechanism of growth of gastric carcinoma.

Animals↗

PubMed1992

Identification and characterization of virK, a virulence-associated large plasmid gene essential for intercellular spreading of Shigella flexneri.

Seven virulence loci have been identified by Tn5 insertion mutagenesis on the large 230 kb plasmid (pMYSH6000) of Shigella flexneri 2a. In this study, we used Tn10 insertion mutagenesis and identified a novel virulence locus on pMYSH6000 responsible for bacterial spread. Characterization of the invading bacteria of the Tn10 insertion mutants in the epithelial cells revealed that the bacteria were capable of at least some intracellular spreading but not intercellular spreading. Immunoblot analysis of lysates of the Tn10 insertion mutants with a VirG-specific antipeptide antibody revealed diminished levels of the 116 kDa VirG protein. The virG mRNA in the mutants, however, was expressed at the same level as that in the wild type. The DNA region required for the virulence phenotype was localized to a 1.6 kb DNA sequence in the SalI-K fragment on the plasmid, and thus the locus was designated virK. Expression of virK in Escherichia coli using a T7 RNA polymerase-dependent promoter system yielded a 36 kDa protein. The nucleotide sequence of 1642 bp encoding VirK function was determined, and an open reading frame encoding 316 amino acid residues was shown to encode the VirK protein. The virK region was highly conserved among the large virulence plasmids of shigellae and enteroinvasive Escherichia coli. These results suggest that VirK function is an essential virulence determinant for shigellae involved in the expression of virG gene product at post-transcriptional level.

Amino Acid Sequence↗

PubMed1992

vacB, a novel chromosomal gene required for expression of virulence genes on the large plasmid of Shigella flexneri.

Shigellae, the causative agents of bacillary dysentery, are capable of adhering to and invading epithelial cells and spreading into adjacent cells. A chromosomal mutant of Shigella flexneri 2a YSH6000 with reduced invasive capacity was isolated by Tn5 insertion mutagenesis. The linkage of the mutant phenotype to the Tn5 insertion was determined by P1 phage transduction. The site of the Tn5 insertion was assigned to a NotI chromosomal restriction map, confirming that the virulence-associated locus, designated vacB, is a new locus on the chromosome. In the vacB mutant, production of the four plasmid-encoded virulence antigens, IpaB, -C, and -D and VirG, decreased to a low level compared with that in the wild type. In contrast, levels of transcription of the operons for virG, ipa, region-3.4, region-5, virF, and virB on the large plasmid, as determined by Northern dot blotting, were unaffected in the vacB mutant. Furthermore, transcriptional activation of the ipa operon by exploiting a tac promoter could not restore the vacB mutant to production of the same levels of the IpaB, -C, and -D proteins as those in the wild type, indicating that the vacB locus is involved in expression of the vir genes on the large plasmid at the posttranscriptional level. Cloning followed by nucleotide sequencing of the vacB region showed it to contain a 2,280-bp open reading frame encoding an 86.9-kDa protein located 669 bp downstream from the 3' end of the open reading frame for the purA gene. Disruption of the vacB gene of other serotypes of Shigella spp. and enteroinvasive Escherichia coli (EIEC) resulted in reduced expression of virulence phenotypes, indicating that the vacB gene encodes a novel type of virulence-associated gene required for the full expression of the virulence phenotype of Shigella spp. and EIEC.

Amino Acid Sequence↗

PubMed1992

Construction of a continent catheterizable urinary valve from a gastric segment in dogs.

We constructed a continent, catheterizable urinary valve from a gastric segment in 7 dogs. A vascularized gastric segment was isolated from the greater curvature and was tubularized. A cuff was made at the distal end of the tube. The gastric tube was anastomosed to the dome of the bladder with intussusception of the cuff portion into the bladder cavity. The valve provided continence over a wide range of bladder pressure. However, an ulcer of the bladder developed where the gastric mucosa of the cuff faced the bladder mucosa in 5 dogs, with a resultant intraperitoneal perforation in 2 dogs. The development of the bladder ulcer may be a serious complication of an anastomosis of an isolated gastric segment to the bladder.

Animals↗

PubMed1992

Mastoparan-induced hormone release from rat pancreatic islets.

Mastoparan, a tetradecapeptide purified from wasp venom, stimulates insulin and glucagon release by rat pancreatic islets in a dose-related manner. In perifusion experiments, mastoparan produces monophasic hormone release, which ceases within 10 min of removal of the peptide. After exposure of the isles to mastoparan, glucose-induced insulin release is clearly retained. In incubation experiments, mastoparan-induced insulin release is greatly blocked by pretreatment of the islets with pertussis toxin or neomycin (inhibitor of phosphoinositide turnover) or by lowering the ambient temperature to 17 C. Pretreatment of the islets with nifedipine (calcium channel blocker), H-7 (inhibitor of A- and C-kinase), somatostatin, or divalent cation-free medium does not affect the response to mastoparan. Pretreatment with parabromophenacylbromide (phospholipase-A2 inhibitor) does not block the response induced by a high concentration of (58 microM) mastoparan. The peptide does not stimulate insulin synthesis during 30 min of incubation. Mastoparan raises the cytosolic free Ca2+ concentration, measured by fura-2, in isolated islet cells at normal (1.9 mM) and very low (6.5 microM) extracellular Ca2+ concentrations. Intravenous administration of mastoparan in rats causes a significant elevation of both insulin and glucagon. Together with the previous data, we conclude that mastoparan stimulates islet hormone release through a temperature-dependent process mediated by pertussis toxin-sensitive GTP-binding protein(s). Activation of phospholipase-C and liberation of intracellular Ca2+ are likely to be coupled to exocytosis. Ca2+ influx through the Ca2+ channel and protein kinase-A and -C appear not to be involved in mastoparan's hormone-releasing action. Phospholipase-A2 may be involved in the hormone release induced by low, but not high, concentrations of the peptide.

Animals↗

PubMed1992

[The study of Chinese herbal medicinal prescription with enzyme inhibitory activity. VI. The study of makyo-kanseki-to with adenosine 3',5'-cyclic monophosphate phosphodiesterase].

A Chinese herbal medicinal prescription, Makyo-kanseki-to, was studied for the inhibitory activity of adenosine 3',5'-cyclic monophosphate (cAMP) phosphodiesterase. The effect for the inhibitory activity of cAMP phosphodiesterase by combination with constituent crude drugs of the prescription was studied. Gypsum acted as a mitigatory component for Ephedra herb and Glycyrrhiza in cAMP phosphodiesterase inhibition test.

3',5'-Cyclic-AMP Phosphodiesterases↗