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Biomedical subjects

N Okada

Publications and source records attributed to N Okada.

At least 307 records · Page 17Linked to original sources
PubMed1993

Characterization of pigmented granules in minocycline-induced cutaneous pigmentation: observations using fluorescence microscopy and high-performance liquid chromatography.

We describe a technique to facilitate histopathological detection and quantitative measurement of trace amounts of tissue minocycline. In a patient with minocycline-induced hyperpigmentation, a series of biopsies were taken from the affected skin over a period of 54 months, and examined for tissue minocycline deposition. Frozen sections treated with 1 M MgCl2-ethanol yielded minocycline-specific yellowish fluorescence, the location of which corresponded to clumps of granular deposits in the dermis. A decrease in the number of fluorescent granules correlated with the clinical resolution of hyperpigmentation and a significant decrease in the tissue minocycline level. Our data also provide further support for the concept that the pigment granules contain insoluble complexes of minocycline chelated with iron. The fluorescence technique is simple, sensitive, and reproducible.

Chromatography, High Pressure Liquid↗
PubMed1993

Positive transcriptional control of mry regulates virulence in the group A streptococcus.

Transcription of the antiphagocytic M protein in the group A streptococcus (Streptococcus pyogenes) is environmentally regulated in response to CO2 and requires Mry, a trans-acting positive regulatory protein. We have examined the role of Mry in environmental regulation by analysing the factors that regulate expression of the gene that encodes Mry (mry). By employing a strategy that utilizes integrational plasmids, it was found that expression of mry requires the participation of DNA sequences that extend 473 base pairs upstream of the Mry coding region. Transcription of mry, as analysed in S1 nuclease protection assays, is initiated from two separate promoters located within this extended regulatory region. Construction and analysis of transcriptional fusions between the mry promoters and a promoterless chloramphenicol acetyltransferase gene demonstrated that mry is autoregulated and environmentally regulated in response to the level of CO2. These data suggest a model for the regulation of virulence in S. pyogenes where positive transcriptional control of mry in response to environmental stimuli regulates the expression of the M protein.

Amino Acid Sequence↗
PubMed1993

Possible link between a low prevalence of cardiovascular disease and mild dyslipidaemia: a study in Japanese patients with type 2 diabetes.

In 98 Japanese patients with Type 2 diabetes mellitus, serum total cholesterol, triglyceride, high density lipoprotein cholesterol (HDL-C), free fatty acid (FFA), and apolipoproteins (apo) A-I, A-II, B, C-II, C-III, and E were determined. The data were compared with those in 47 normolipidaemic normal controls. The total cholesterol value of the diabetic patients was also compared to that of a general population (n = 2227). The diabetic patients were separated into those with cardiovascular disease (n = 20) and without it (n = 78) and a comparison of clinical characteristics and dyslipidaemia was also performed. The diabetic patients had slightly but significantly higher FFA, LDL-C, apo B, C-II, C-III, E, and B/A-I, and lower apo A-I and A-II compared to the normal controls. The total cholesterol level of the diabetic patients (5.17 +/- 0.96 mmol-1) was not significantly higher than that of the general population (5.12 +/- 0.91 mmol-1). By multivariate stepwise discriminant analyses, only total cholesterol significantly discriminated the patients with and without cardiovascular disease. In Japanese patients with Type 2 diabetes, a diabetic population with a very low prevalence of cardiovascular disease, high total cholesterol is a risk factor for developing cardiovascular disease. Nevertheless, a markedly low prevalence of cardiovascular disease in Japanese with Type 2 diabetes compared to Caucasian counterparts may partly be due to the mildness of dyslipidaemia.

Aged↗
PubMed1993

Analysis of Streptococcus pyogenes promoters by using novel Tn916-based shuttle vectors for the construction of transcriptional fusions to chloramphenicol acetyltransferase.

We have developed a series of shuttle vectors based on the conjugative transposon Tn916 that have been designed for the analysis of transcriptional regulation in Streptococcus pyogenes and other gram-positive bacteria. Designated the pVIT vectors (vectors for integration into Tn916), the vectors are small, stable plasmids in Escherichia coli to facilitate the fusion of promoters from cloned S. pyogenes genes to a promoterless gene which encodes chloramphenicol acetyltransferase. The vectors each contain one or more small regions of Tn916 to direct the integration of the transcriptional fusion into the transposon via homologous recombination following transformation of S. pyogenes or other suitable gram-positive hosts. Integration can be monitored by the inactivation or replacement of an antibiotic resistance determinant in modified derivatives of Tn916. Promoter activity can then be quantitated by the determination of chloramphenicol acetyltransferase-specific activity. In addition, since integration is into loci that do not disrupt the conjugative transpositional functions of Tn916, the vectors are useful for analysis of regulation in strains that are difficult or impossible to transform and can be introduced into these strains by conjugation following transformation of an intermediate host. The promoters for the genes which encode both the M protein and protein F of S. pyogenes were active in pVIT vectors, as was the region which controls transcription of mry, a trans-acting positive regulator of M protein expression. However, neither of the two characterized promoters for mry demonstrated activity when independently analyzed in pVIT-generated partial diploid strains, suggesting that regulation of mry is more complex than predicted by current models. The broad host range of Tn916 should make the pVIT vectors useful for analysis of regulation in numerous other bacterial species.

Antigens, Bacterial↗
PubMed1993

Loss of glomerular anionic sites and the development of albuminuria in rats with streptozotocin-induced diabetes.

Examination was made of changes in the anionic sites of the glomerular basement membrane (GBM) in rats with streptozotocin (STZ)-induced diabetes by the immersion method of polyethyleneimine (PEI). PEI particles in GBM of diabetic rats significantly decreased from the 1st through the 8th week. Urinary albumin excretion in diabetic rats significantly increased at the 2nd but not earlier week. Insulin treatment effectively prevented decrease in PEI particles in STZ-injected rats. In rats with STZ-induced diabetes, initial renal alteration was disturbance of the charge barrier, followed by the development of albuminuria. Continued deterioration of anionic sites and possibly additional disturbance of size barrier were considered responsible for the development of albuminuria. Insulin treatment appears to prevent the loss of anionic sites of GBM.

Albuminuria↗
PubMed1993

Expression of 20 KD homologous restriction factor of complement on myocardial cells: an immunohistochemical study using acetone-fixed and paraffin-embedded tissues.

Expression of 20 KD homologous restriction factor of complement (HRF20) (CD59) in normal human heart was immunohistochemically examined with monoclonal antibody (MAb) 1F5. HRF20 was clearly demonstrated on the cell surface membrane and intercalated discs of myocardial cells throughout the ventricular walls. Therefore, this factor may protect normal cardiomyocytes from complement deposition, which has been demonstrated on infarcted cardiomyocytes. Expression of HRF20 was also observed on endothelial cells of the endocardium and on blood vessels, including arteries, capillaries, and veins, and on the Schwann-cell sheath of peripheral nerve fibers. In the present study, we found that the epitopes of HRF20 were well preserved for immunohistochemistry even in acetone-fixed and paraffin-embedded tissues, as well as in frozen tissues that have been conventionally used for HRF20. This method using paraffin sections allows for easier staining and greater accuracy in histological examination.

Acetone↗
PubMed1993

Induction of mucosal disease in cattle persistently infected with noncytopathic bovine viral diarrhea-mucosal disease virus by superinfection with cytopathic bovine viral diarrhea-mucosal disease virus.

Three head of cattle persistently infected with noncytopathic bovine viral diarrhea-mucosal disease virus (ncBVD-MDV) were superinfected naturally or experimentally with cytopathic bovine viral diarrhea-mucosal disease virus (cBVD-MDV). In the naturally superinfected case, one animal manifested pyrexia and severe diarrhea, and died without developing antibodies to cBVD-MDV. However, another animal survived with only continual slight anorexia and pyrexia, and developed strong resistance to the superinfected strain. In the experimental cases, induction of MD was unsuccessful in two persistently infected cattle when superinfected with cBVD-MDV antigenically heterologous for persistently infected ncBVD-MDV. They also developed antibodies to the cBVD-MDV strain with which they had been infected. After 6 months, these cattle were infected again with a cBVD-MDV strain different from that used in the previous experiment. One animal infected with this strain, which was antigenically homologous to the persistently infected strain, died after developing MD symptoms without developing antibodies to the infecting strain. It is suggested that the antigenic relationship between the persistent ncBVD-MDV and the superinfected cBVD-MDV was an important factor in developing MD.

Animals↗
PubMed1993

Preparation and application of monoclonal antibodies for a sandwich enzyme-linked immunosorbent assay of the major soybean allergen, Gly m Bd 30K.

In order to obtain probes suitable for the determination of the major soybean allergen, Gly m Bd 30 K, in soybean-related processed foods, we have prepared two monoclonal antibodies, F5 of IgG2a and H6 of IgM, by the fusion of P3U1 myeloma cells with the spleen cells of BALB/c mice immunized with the reductively carboxymethylated allergen (RCM-allergen). The two monoclonal antibodies were shown to be specific to the intact allergen as well as the RCM-allergen and to recognize distinct epitopes on the allergen. Of the monoclonal antibodies, F5 was conjugated with peroxidase. H6 and the labeled F5 were applied as the fixing antibody and the labeled first antibody, respectively, for a direct sandwich enzyme-linked immunosorbent assay of the allergen. When the allergen was extracted from the soybean-related foods with Tris-HCl buffer containing sodium dodecylsulfate and mercaptoethanol, the allergen, Gly m Bd 30 K, was shown to be measured in a range of 5-500 ng in this assay.

Allergens↗
PubMed1993

[Screening of bladder cancer by a combination of transabdominal ultrasonography and urine cytology].

We evaluated the presence or absence of bladder cancer by a combination of transabdominal ultrasonography and urine cytology in 60 patients who had been suspected of having bladder cancer. All patients then underwent cystoscopy, and biopsy or resection if necessary, and 24 patients were diagnosed as having bladder cancer. By the combination of ultrasonography and urine cytology the diagnosis was correct in 23 patients accounting for 96% of sensitivity, and the misdiagnosis was made in only one patient who had undergone BCG therapy for carcinoma in situ but had submucosal invasive bladder cancer. Because of the high sensitivity rate, we believe that the combination of transabdominal ultrasonography and urine cytology should be the first-choice examinations for patients who are suspected of having bladder cancer.

Adult↗
PubMed1993

[Circadian blood pressure pattern in the patients with chronic glomerulonephritis].

Circadian blood pressure pattern in the patients with chronic glomerulonephritis was studied by ambulatory 24-hour blood pressure monitoring (ABPM). Subjects were 32 patients and were divided into three groups with various renal function; Ccr of 10 patients were normal (Ccr > or = 70 ml/min), 10 patients 30 < or = Ccr < 70 ml/min and the Ccr were below 30 ml/min in the other 12 patients. Blood pressure levels were significantly higher in reduced Ccr groups as compared with normal Ccr cases. The blood pressure gradient between day-time (7:00-19:00) and sleeping time (1:00-5:00) significantly decreased in the patients with renal impairment as compared with normal Ccr cases. And it positively correlated with Ccr (r = 0.51, p < 0.01). These results indicate that the patients with reduced renal function in chronic glomerulonephritis show abnormal circadian blood pressure pattern and nocturnal hypertension, which may require novel modification of antihypertensive treatment.

Blood Pressure↗
PubMed1993

[Predictability of creatinine clearance from serum creatinine in chronic glomerulonephritis].

We evaluated the formulas of urine-free prediction of creatinine clearance (CCr) for clinical use in the patients with chronic glomerulonephritis (CGN). Subjects were 246 patients with CGN diagnosed by renal biopsy with range from normal renal function to end stage renal failure. CCr were measured exactly with urine collections more than 2 times and compared with the values calculated using four urine-free mathematical formulas of Cockcroft et al, Mawer et al, Konishi et al, and Tozune et al. Strong, statistically significant correlations were observed between CCr estimated with each prediction method and measured CCr (r > or = 0.946). However, the latter two formulas tended to overestimate the values. Predicted errors more than 20% of the formula of Cockcroft et al, were the least. And their formula was the easiest for clinical use because of the simplicity for learning by heart. We conclude that these four formulas can be used with reasonable accuracy in the patients with CGN from normal renal function to end stage renal failure, and the formula of Cockcroft et al, is the most recommendable for clinical use.

Adolescent↗
PubMed1993

[A case of spontaneous spinal epidural hematoma].

A 14-month-old girl with spontaneous spinal epidural hematoma and complete postoperative recovery was described. MRI proved to be a sensitive tool in identifying the nature and extent of this lesion. A review of literature was made with particular emphasis on the pediatric age group.

Age Factors↗
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↗