Search PubMed⌕ Search

Biomedical subjects

N Yoshikawa

Publications and source records attributed to N Yoshikawa.

At least 109 records · Page 6Linked to original sources
PubMed1996

Improvement of insulin sensitivity contributes to blood pressure reduction after weight loss in hypertensive subjects with obesity.

To access the role of insulin resistance in obesity hypertension, we examined the change of insulin sensitivity after weight loss in 24 obese hypertensive subjects by the euglycemic hyperinsulinemic glucose clamp method. The results of the 4-week calorie-restricted diet were a weight loss of 10.2% (from 74 +/- 12 to 67 +/- 11 kg, P < .01) and a decrease in mean blood pressure of 13.1% (from 124 +/- 7 to 107 +/- 9 mm Hg, P < .01). A decrease in plasma norepinephrine (from 208 +/- 74 to 142 +/- 52 pg/mL, P < .01) was associated with decreases in plasma renin activity (from 1.06 +/- 0.98 to 0.62 +/- 0.63 ng/mL per hour, P < .01) and serum aldosterone (from 70 +/- 28 to 57 +/- 24 pg/mL, P < .05). Glucose infusion rate increased significantly (42.9%), from 809 +/- to 1155 +/- 251 mumol/m2 per minute. The insulin sensitivity index, which is a measure of the glucose infusion rate divided by plasma insulin, increased significantly (42.6%), from 10.8 +/- 3.5 to 15.4 +/- 4.4 (mumol/m2 per minute)/(microU/mL). Stepwise multiple linear regression analysis showed that changes of plasma norepinephrine, insulin sensitivity index, plasma renin activity, and age were significant predictive factors for the change of mean blood pressure after weight loss. These results indicate a distinct relation between an improvement of insulin sensitivity and a decrease in blood pressure after weight loss in obese hypertensive subjects. The decrease in blood pressure after weight loss is probably related to the suppression of sympathetic nervous activity.

Anthropometry↗
PubMed1996

Thyroid cell proliferation-inhibiting activity in serum of patients with chronic renal failure on hemodialysis.

To investigate the possible humoral factor(s) influencing thyroid cell activity in chronic renal failure, we measured serum activity which stimulates or inhibits the [3H]thymidine incorporation by using a cultured functioning rat thyroid cell line (FRTL-5 cells) in 17 patients on hemodialysis and 19 healthy controls. Polyethylene glycol-treated serum was centrifuged and FRTL-5 cells were cultured with the supernatant. Thyroid stimulating activity was determined by [3H]thymidine incorporation after incubation for 72 h. There was no significant difference in [3H]thymidine incorporation between cultures incubated with patient and normal serum, suggesting the absence of the stimulating activity. But when patient serum was added to cultures together with 20 or 50 microU/ml of TSH, the TSH-stimulated increase in [3H]thymidine incorporation was significantly decreased, indicating the presence of thyroid inhibiting activity, which possibly inhibits the thyroid cell growth. This activity was not significantly altered by hemodialysis. No significant correlation was observed between this activity and serum levels of thyroid hormones or the iodine concentration. Patients on hemodialysis therefore have serum thyroid inhibiting activity which is nondialysable, differs from iodine, and could influence the thyroid cell growth.

Adult↗
PubMed1996

Plasma free thyroxine (FT4) concentrations during hemodialysis in patients with chronic renal failure: effects of plasma non-esterified fatty acids on FT4 measurement.

Plasma free T4 (FT4) concentrations could be increased during hemodialysis in patients with chronic renal failure (CRF) because an increase in non-esterified fatty acids (NEFA) could interfere with the binding of T4 to thyroxine-binding globulin. To evaluate the effect of hemodialysis on the FT4 concentration in patients with CRF, we measured the FT4 in 39 patients with CRF by four assay methods including equilibrium dialysis, the 125I-T4 analog method and enzyme immunoassay. The addition of the fatty acid sodium oleate to normal pooled sera led to a marked increase in FT4 as measured by equilibrium dialysis (Model FT4). A moderate increase in the serum FT4 concentration also was observed with an IMX enzyme immunoassay kit, whereas the Coat-A-Count analog method demonstrated no interference by sodium oleate. The mean serum FT4 prior to hemodialysis measured by equilibrium dialysis did not differ significantly from that in the normal control, although those measured by analog methods (Coat-A-Count and Amerlex) and IMX were subnormal. The FT4 by IMX were albumin-dependent, and the values decreased as the samples were serially diluted, but Model FT4 was not affected by the albumin level or the serial dilution. FT4 by Model FT4 showed a marked increase beginning 10 min after the start of dialysis, and it correlated well with the plasma concentration of NEFA and the NEFA/albumin molar ratio. The other three assay methods, including one which is not affected by NEFA, did not show a change in FT4 at 10 min, but a significant increase of 11 to 17% was observed by the end of dialysis. The TSH concentration decreased significantly during hemodialysis. These data suggest that (1) the low serum FT4 in hemodialysis patients measured by some immunoassay methods may be an underestimation due to the low albumin level; (2) FT4 actually increases during hemodialysis due to the actual increase in NEFA, although the marked increase in FT4 during hemodialysis as measured by equilibrium dialysis is an overestimation due to the in vitro generation of NEFA; and (3) one should beware of aberrations in thyroid hormone parameters during hemodialysis and potential complications.

Dialysis↗
PubMed1995

Expression, subcellular location and modification of the 50 kDa protein encoded by ORF2 of the apple chlorotic leaf spot trichovirus genome.

A putative movement protein of molecular mass 50 kDa encoded by the ORF2 of the apple chlorotic leaf spot virus (ACLSV) genome was expressed in Escherichia coli using an expression vector and was then used to produce an antiserum. Immunoblot analysis using an antiserum raised against this protein showed that the ORF2 protein of ACLSV was detected in both cell wall and cell membrane fractions prepared from infected Chenopodium quinoa tissues. The ORF2 protein from infected tissues had a molecular mass of 52 kDa, larger than that of the full-length ORF2 protein (50 kDa protein) expressed in E. coli. Incubation of the 52 kDa protein with alkaline phosphatase resulted in a decrease in its apparent molecular mass from 52 kDa to 50 kDa, strongly suggesting that the ORF2 protein of ACLSV is phosphorylated in infected plant tissues.

Base Sequence↗
PubMed1995

Expression of intercellular adhesion molecule-1 on human thyroid cells from patients with autoimmune thyroid disease: study of thyroid xenografts in nude and severe combined immunodeficient mice and treatment with FK-506.

It has been suggested that intercellular adhesion molecule-1 (ICAM-1) may play an important role in the initiation, localization, and perpetuation of autoimmune thyroid diseases (AITD). In an effort to clarify its role, we have investigated the expression of ICAM-1 on thyroid epithelial cells (TEC) of patients with AITD, patients with nontoxic goiter (NTG), and normal subjects (PN) by flow cytometric analysis under basal conditions and after modulation with cytokines, before and after 8 weeks of thyroid tissue xenotransplantation in nude athymic mice (which lyses all passenger lymphocytes), and in severe combined immunodeficient (SCID) mice where these cells survive. Before xenografting, ICAM-1 was expressed on 56% of TEC from Hashimoto's thyroiditis (n = 5), 54% of Graves' disease (n = 6), 15% of NTG (n = 5), and 12% of PN TEC. After the xenografts had been 8 weeks in nude mice, ICAM-1 expression decreased markedly in AITD TEC [from 56% to 10% in Hashimoto's thyroiditis (P < 0.001) and from 54% to 8% in Graves' disease (P < 0.01)], but did not change significantly in NTG or PN. After the xenografts had been 8 weeks in SCID mice, the expression of ICAM-1 was significantly higher on TEC of AITD compared with the same tissue in nude mice. When the SCID mice engrafted with AITD tissue were treated with the anti-CD4+ T (helper) cell agent FK-506, the expression of ICAM-1 was reduced significantly compared with that in the original tissue or that in nontreated mice engrafted with the same tissue. The proportion of TEC that were ICAM-1 positive was up-regulated in all cases by certain cytokines (e.g. interferon-gamma and tumor necrosis factor-alpha applied alone or in combination). We also detected the presence of ICAM-1 in AITD frozen tissues using an immunohistochemical technique. These data suggest a role for ICAM-1 in human AITD. However, the expression of ICAM-1 appears to be a secondary phenomenon in response to the immune assault, rather than a primary event. Our results support the idea that TEC may act as passive captives to immunological events in human AITD.

Animals↗
PubMed1995

Bioactivity of thyrotropin (TSH) in patients with central hypothyroidism: comparison between in vivo 3,5,3'-triiodothyronine response to TSH and in vitro bioactivity of TSH.

To investigate the cause(s) of central hypothyroidism with normal or elevated TSH concentrations, we evaluated the bioactivity of serum TSH as well as pituitary and thyroid function. Seven hypothyroid patients had documented deficiencies of anterior pituitary hormones other than TSH. Basal TSH concentrations ranged from 2.2-14.8 microU/mL. Six patients had low T4 and free T4 concentrations; the remaining patient had a low free T4 and a low normal T4 level with an elevated TSH concentration of 14.4 microU/mL. The mean increment in TSH 30, 60, and 90 min after TRH administration (mean delta TSH) in these patients was 13.5 +/- 9.1 microU/mL (mean +/- SD), which was not significantly different from the value in controls (9.2 +/- 3.5 microU/mL). However, the ratio of the T3 increment at 120 min (delta T3) to mean delta TSH (delta T3/mean delta TSH) in patients was 53.9 +/- 29.3 ng/microU, significantly lower than the control value of 239.5 +/- 97.5 ng/microU (P < 0.01), suggesting that the thyroid response to endogenous TSH was blunted. The serum T4 concentration correlated with the mean delta TSH in these patients (r = 0.78; P < 0.05), suggesting that hypothyroidism is dependent on conserved pituitary function. The mean bioactivity to immunoreactivity ratio of basal TSH in patients was 0.97 +/- 0.27 and was not significantly different from the normal value of 1.05 +/- 0.22. One of the two patients with high basal TSH (> 10 microU/mL) had a ratio of 0.59, which is just below the mean +/- SD of normal subjects (0.61), suggesting that most patients had normal TSH bioactivity in vitro. Our findings suggest that in vivo bioactivity of TSH is decreased because of a pituitary disorder, but in vitro bioactivity of TSH is variable in patients with central hypothyroidism.

Adult↗
PubMed1995

Activation of T lymphocyte subsets by synthetic TSH receptor peptides and recombinant glutamate decarboxylase in autoimmune thyroid disease and insulin-dependent diabetes.

We have postulated that a defect in specific antigenic induction of suppressor T lymphocytes may account for the immunoregulatory disorder in autoimmune thyroid disease. In this context, we have measured the proliferative responses of peripheral blood mononuclear cells (PBMC) to the synthetic peptides corresponding to the extracellular domain of the TSH receptor (TSHR) and recombinant glutamate decarboxylase (GAD65) by means of 3H thymidine incorporation. We have also studied the antigenic activation of CD4+ and CD8+ T lymphocytes by measuring human leukocyte antigen-DR (HLA-DR) expression on the cell surface by flow cytometric analysis. PBMC obtained from 47 patients with Graves' disease (GD) [including 19 hyperthyroid GD (hyper GD)], 18 with Hashimoto's thyroiditis (HT), 7 with nontoxic nodular goiter (NG), 18 with insulin-dependent diabetes (IDDM), and 20 normal controls (N), were cultured for 7 days in the presence or absence of the pool peptides representing 3 different segments of TSHR or GAD65 at final concentration of 30 micrograms/mL or 10 micrograms/mL. The proportion of subjects whose PBMC gave a positive proliferative response with a stimulation index (SI) of over 2.3 (i.e. above the mean +2 SD for N) to TSHR peptides was significantly higher in the hyper GD group than among euthyroid GD (eu GD), HT, IDDM, and N group. The corresponding differences in mean SI provided analogous results, showing significant responses above normal in only hyper GD. The CD4+ T lymphocytes from hyper GD group were significantly more activated by TSHR peptides compared to eu GD, HT, IDDM, and N, and this induction correlated to their thyroid hormone levels. Quite differently, the activation of CD8+ T lymphocytes from both hyper GD and eu GD group in response to TSHR peptides was impaired compared to HT, IDDM, and the N group; in contrast to the findings with CD4+ T lymphocytes, this was independent of thyroid hormone levels. On the other hand, while the CD8+ T lymphocytes from GD and N groups were activated equally by GAD65, the activation of CD8+ T lymphocytes from the IDDM group by GAD65 was impaired compared to the GD and N groups. In conclusion, the activation of CD8+ T lymphocytes from GD and IDDM by relevant antigens (i.e. TSHR peptides for GD and GAD65 for IDDM) was impaired, but not by irrelevant antigens (i.e. GAD65 for GD and TSHR peptides for IDDM). There was also a modest stimulation of CD8+ T cells from all groups by tetanus toxoid and cardiac myosin light chain peptide, both irrelevant antigens.(ABSTRACT TRUNCATED AT 400 WORDS)

Adolescent↗
PubMed1995

Thyroid stimulating antibody in sera of Graves' ophthalmopathy patients as a possible marker for predicting the efficacy of methylprednisolone pulse therapy.

Nine patients with Graves' ophthalmopathy (GO) were treated with intravenous methylprednisolone pulse therapy and followed up by ophthalmological assessment, magnetic resonance imaging, and thyroid-associated autoantibody (thyroid stimulating antibody (TSAb), TSH binding inhibitor immunoglobulins (TBII), and anti-eye muscle antibody (EMAb)). Ophthalmological assessment was performed by the ophthalmopathy index (OI) which was made on the basis of the system recommended by the American Thyroid Association Committee. EMAb was expressed as the ratio of density of the 64 kDa band of eye muscle membrane to that of 92 kDa non-specific band found with all normal sera when assessed by western blotting. Five patients with mild ophthalmopathy (OI < 4) did not show progressive improvement in OI. Three of 4 patients with severe eye disease (OI > 4) showed a progressive and distinct improvement in OI. These 3 patients had high TSAb levels before methylprednisolone pulse therapy. One patient with severe ophthalmopathy did not respond to this pulse therapy; this patient's TSAb was negative. A significant positive correlation was observed between the activity of TSAb before treatment and the improvement in OI (delta OI) (r = 0.86, P < 0.01, n = 9). The relationship between delta OI and EMAb did not reach significance. These results suggest that TSAb in sera of GO patients can be a useful marker for predicting the efficacy of methylprednisolone pulse therapy.

Adolescent↗
PubMed1995

Mutation in alpha 5(IV) collagen chain gene in nonfamilial hematuria.

Alport syndrome is an inherited disorder characterized by progressive nephritis with ultrastructural basket-weave changes of the glomerular basement membrane and neurosensory deafness. Mutations in the COL4A5 gene encoding the Type IV collagen alpha 5 chain have been reported to occur in patients with X-linked Alport syndrome. A girl with hematuric nephritis, characteristic basket-weave glomerular basement membrane changes, and abnormal expression of the Type IV collagen alpha 5 chain immunohistochemically, but no family history of nephritis, was identified. Mutation detection enhancement gel electrophoresis of the polymerase chain reaction-amplified exons of COL4A5 from this patient revealed a sequence variant in the exon 50 region. Sequence analysis of her polymerase chain reaction product demonstrated a single-base (C; nucleotide 4728 from the 5' end) deletion in exon 50. This novel mutation alters the reading frame and introduces a translation stop codon that would be expected to result in a noncollagenous domain with only 209, instead of the normal 229, amino acid residues. Gene tracking with restriction enzyme AfIIII demonstrated that her mother was normal. These findings represent a new mutation of the X-linked Alport syndrome in this patient and demonstrate that a COL4A5 gene mutation causes the abnormal expression of Type IV collagen alpha 5 chain protein.

Base Sequence↗
PubMed1995

Polymorphism of immunoglobulin heavy chain switch region gene in children with severe IgA nephropathy.

We examined restriction fragment length polymorphisms (RFLPs) of the switch region genes of the IgM (S mu) and IgA1 (S alpha 1) heavy chain in 78 Japanese children with IgA nephropathy and 88 normal Japanese controls. Genomic DNA obtained from patients and controls was digested with the restriction endonuclease SacI, transferred to nylon membrane using Southern blot procedure, and hybridized with a DNA probe homologous to S mu. This probe detects RFLPs at the S mu and S alpha 1 loci by enhanced chemiluminescence. The genotypic frequency of the S mu and S alpha 1 alleles in patients with IgA nephropathy was similar to normal controls. However, there was a significant association of genotypes with the pathological severity. There was a decreased frequency of the 2.6/2.1 kb S mu heterozygous genotype in patients showing diffuse mesangial proliferation compared to controls or patients showing minimal or focal mesangial proliferation. Our results suggest that immunoglobulin heavy chain switch region genes may not influence susceptibility to IgA nephropathy in children, but may influence the pathological expression of childhood IgA nephropathy.

Alleles↗
PubMed1995

The effect of interleukin-2 on suppressor T lymphocytes in autoimmune thyroid disease.

We have investigated the effects of interleukin-2 (IL-2) on the activation of suppressor T lymphocytes in autoimmune thyroid disease (AITD), with insulin-dependent diabetes mellitus (IDDM) as an autoimmune disease control; this was accomplished by measuring the expression of major histocompatibility complex class II (HLA-DR), CD25 (IL-2 alpha receptor (R)), and IL-2 beta R expression on their surfaces by flow cytometric analysis. Peripheral blood mononuclear cells (PBMC), obtained from 10 patients with Graves' disease (GD), 11 with Hashimoto's thyroiditis (HT), 9 with insulin-dependent diabetes mellitus (IDDM), and 10 normal persons (N), were cultured for 7 d in the presence or absence of IL-2 at a final concentration of 50 U/mL. CD8+ cells were isolated from cultured PBMC with immunomagnetic beads, and were stained with fluorescent-conjugated monoclonal antibodies (anti-CD11b, anti-IL-2 alpha R, anti-IL-2 beta R, and anti-HLA-DR); the activation of CD8+CD11b+ ("suppressor") T cells (Ts) by IL-2 was then analyzed on a flow cytometer. In the absence of IL-2, i.e., in the autologous mixed lymphocyte reaction (AMLR), Ts from patients with GD, HT, and IDDM showed significantly lower activation as compared to N when analyzed by HLA-DR expression, but were not significantly different when IL-2R expression was measured. We determined the Stimulation Index (SI) of the activation of T lymphocytes by IL-2 for comparison between N and patients. With stimulation of 50 U/mL of IL-2, SI of HLA-DR+ Ts was significantly (p < 0.05 to 0.01) lower in GD, HT, and IDDM as compared with N.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

A quantitative analysis of the glomeruli in focal segmental glomerulosclerosis.

Quantitative analysis of the glomerular area, mesangial matrix and mesangial cells was performed using renal biopsy specimens from 22 children with focal segmental glomerulosclerosis (FSGS) and 20 with minimal change nephrotic syndrome (MCNS). Non-sclerotic glomeruli were examined. All children in both groups showed nephrotic syndrome at the time of biopsy. Children with benign haematuria were examined as controls. Glomerular area increased with age in the FSGS, MCNS and control groups. The glomerular area was significantly greater in FSGS (1.5 +/- 0.4 x 10(4) microns 2) than in MCNS (1.2 +/- 0.2 x 10(4) microns 2) or in controls (1.2 +/- 0.3 x 10(4) microns 2) (P < 0.05). Mesangial matrix was increased with age in the three groups. The mesangial matrix was significantly increased in FSGS (28.3 +/- 4.0%; mesangial matrix area/glomerular area) compared with MCNS (24.9 +/- 4.1%) and controls (23.0 +/- 3.0%) (P < 0.01). These findings suggest that both glomerular hypertrophy and mesangial matrix increase in non-sclerotic glomeruli in FSGS may lead to glomerular sclerosis.

Adolescent↗
PubMed1994

Immunohistochemical study of alpha 1-5 chains of type IV collagen in hereditary nephritis.

The distribution of alpha 1-5 chains of type IV collagen [alpha 1-5(IV)] in the glomerular basement membrane (GBM) and epidermal basement membrane (EBM) of 23 families with hereditary nephritis was examined by indirect immunofluorescence. These families were divided into three clinicopathological groups. Group I (10 families) patients showed a widespread "basket weave" pattern of the GBM and a family history of nephritis was present. Group II (6 families) patients showed a widespread "basket weave" change without a family history of nephritis. Group III (7 families) patients showed a widespread attenuation of the GBM but no "basket weave" change, and had a family history of nephritis and chronic renal failure. alpha 1(IV) and alpha 2(IV) were present in all affected and unaffected family members and controls. All normal family members and controls expressed alpha 3(IV), alpha 4(IV) and alpha 5(IV) in the GBM and alpha 5(IV) in the EBM in a diffuse pattern. All group I families and three of the group II families exhibited complete loss of the alpha 5(IV) antigen from the GBM and EBM in male patients, and segmental loss of the alpha 5(IV) antigen in female patients. In these families the alpha 3(IV) and alpha 4(IV) antigens were completely lost from the GBM in male patients with severe nephritis, whereas alpha 3(IV) alpha 4(IV) were present but diminished in male patients with mild nephritis. Three group II and all group III families expressed the alpha 3-5(IV) antigens in an identical manner to that of normal controls. These findings indicate that the heterogeneity of hereditary nephritis reflects a variety of aberrant expression patterns of alpha 3-5(IV) and that immunohistochemical examination of alpha 5(IV) in the EBM is a useful method for the diagnosis of X-linked Alport syndrome.

Adult↗
PubMed1994

Angiotensin II type 1 receptor gene abnormality in a patient with Bartter's syndrome.

Administration of a selective angiotensin I type 1 receptor (AT1) antagonist in animals not only nullifies the vasopressor action of angiotensin II, but also induces chloriduria and kaliuria, juxtoglomerular apparatus (JGA) hypertrophy and hyperreninemia, features characteristic of human Bartter's syndrome. We, therefore, explored the possibility that Bartter's syndrome may involve an AT1 abnormality. Using a pair of AT1-specific oligonucleotide primers and two different DNA polymerases (Taq and Pfu), we amplified the approximately 1 kb AT1 coding region of genomic DNA isolated from leukocytes of five patients with Bartter's syndrome by PCR and analyzed the sequence of the product. While the sequence of all clones from four patients were identical to that already reported for the normal human AT1 DNA sequence, 50% of the clones from one patient with Bartter's syndrome were found to have A-->G transition at nucleotide 931 which causes an amino acid substitution (arg-->gly) on the carboxy-terminal cytosolic tail of AT1. This mutation was not found in DNA from 50 normal controls which were screened by restriction enzyme digestion pattern of the PCR products of this region. As PCR-amplified AT1 DNA clones from four other individuals with Bartter's syndrome did not display any abnormality in the coding region, the possibility exists that Bartter's syndrome consists of multiple disease entities, where an AT1 gene abnormality represents a specific subgroup of the syndrome and/or some abnormality includes mutations outside of the coding region.

Animals↗
PubMed1994

Studies of human peripheral blood mononuclear cells (PBMC) from patients with subacute thyroiditis in severe combined immunodeficient (SCID) mice: less production of human interferon gamma than that seen for Graves' disease.

Human peripheral blood mononuclear cells (PBMC) from 2 patients with de Quervain's subacute thyroiditis (SAT), 2 with Graves' disease (GD), and 3 normal persons (N) were engrafted into severe combined immunodeficient (SCID) mice so as to study whether SAT PBMC would differ immunologically from GD PBMC in vivo. Human IgG was detected in all mice engrafted with PBMC from either group of patients or normal persons. Thyroid Stimulating Antibody (TSAb) was detected in the sera of mice with PBMC from SAT or GD patients, but not N. Thyroperoxidase (TPO)-antibody (Ab) and/or thyroglobulin (Tg)-Ab was detectable in the mice with GD PBMC only, but not in those with SAT or normal PBMC. The production of interferon gamma (IFN gamma) in mice engrafted with N PBMC was 8, 13 and 14 U/ml, similar to values found in sera of SCID mice with SAT PBMC (14 and 11 U/ml), i.e., much lower than that seen for GD PBMC (127 and 78 U/ml); this is consistent with the view that, compared to GD T lymphocytes, that there is probably a lower number of T lymphocytes sensitized to the thyrotrophin (TSH) receptor antigen in SAT patients. Another possibility is that the transient thyroidal antigenic release seen in the acute (hyperthyroid) phase may be insufficient for adequate T cell sensitization. Still other possibilities include the effect of more severe hyperthyroidism of GD on T cell sensitization, and CD4/CD8 cell ratios. In any event, these results are consistent with our previous view that antigenic release in SAT will not itself lead to autoimmune thyroid disease.

Adult↗