PubMed Health⌕ Search

Biomedical subjects

H Asakawa

Publications and source records attributed to H Asakawa.

At least 19 recordsLinked to original sources
PubMed1992

Function of DR-positive thyrocytes from patients with Graves' disease: quantitative analysis of thyroid peroxidase content by fluorescent photometry.

A considerable number of thyrocytes in patients with autoimmune thyroiditis ectopically express HLA-DR antigen. Furthermore, it has been reported that interferon-gamma-induced DR-positive thyrocytes in vitro secrete less thyroid hormone in response to TSH stimulation compared with DR-negative ones. However, the function of the intrinsically DR-positive thyrocytes is unknown. To evaluate their function, we stained by immunofluorescence for both DR antigen and thyroid peroxidase (TPO) in thyroid epithelial cells from patients with Graves' disease. We also measured the quantity of DR antigen and TPO using fluorescent photometry. The content of TPO was not significantly reduced in DR-positive thyrocytes compared with that in DR-negative thyrocytes. The TPO content is one measure of thyrocyte function. There was no significant difference between DR-positive and DR-negative thyrocytes. In conclusion, the function of DR-positive thyrocytes in vivo was not suppressed compared with that of DR-negative thyrocytes.

Adult↗
PubMed1992

Interferon-gamma reduces the thyroid peroxidase content of cultured human thyrocytes and inhibits its increase induced by thyrotropin.

To clarify the role of interferon-gamma (IFN gamma) in autoimmune thyroid diseases, we investigated the effects of IFN gamma on the content of thyroid peroxidase (TPO) and the expression of HLA-DR antigens in cultured normal human thyrocytes. The effect of TSH on the action of IFN gamma was investigated. Immunofluorescence staining and photometric analysis showed that IFN gamma not only induced the expression of DR antigen, but also reduced the content of TPO in a concentration-dependent manner. The addition of TSH increased the content of TPO and enhanced the IFN gamma-induced expression of DR antigen. IFN gamma also inhibited the increase in TPO content induced by TSH. Thus, complex interactions appear to exist between IFN gamma and TSH or thyroid-stimulating antibodies in the modulation of hormone secretion and autoimmune phenomena in the thyroid.

Adenoma↗
PubMed1992

Histamine release and SOD, allopurinol and ranitidine pretreatment in haemorrhagic shock in the rat.

Histamine release have been demonstrated in haemorrhagic shock. There are some observations that oxygen free radicals can cause histamine release. Oxygen free radicals play a role in the pathogenesis of gastric mucosal lesions. The goal of this study was to determine whether ranitidine or SOD and allopurinol pretreatment modify the histamine release during and after the haemorrhagic shock in the rat. In the anaesthetized rat 0.1 N HCl was instilled into the stomach and the rat was bled to reduce the blood pressure to 30 mmHg for 20 min. The shed blood was reinfused. Twenty min later the stomach was removed. The area of gastric mucosal lesions were measured, histological grading was made. Blood samples taken from the carotid artery were examined by radioimmunoassay (IMMUNOTECH) to determine the plasma histamine level. Plasma histamine level did not change significantly during the preparative surgery, but there was a significant increase of histamine level by the end of shock period. After the reinfusion of the blood the plasma histamine remained essentially at the same level for five min. Oxygen free radicals did not cause an important histamine release. By the end of the experiment the histamine level decreased dramatically. Ranitidine, allopurinol and SOD pretreatment provided significant protection against the gastric mucosal lesions. Allopurinol and SOD did not influence significantly the histamine level. Ranitidine caused significant histamine release immediately after the injection and every histamine value was significantly higher in this group except for the final value which was lower than the control one. The oxygen free radicals were not found as endogenous histamine releasers in this study.

Allopurinol↗
PubMed1992

Cell-to-cell communication in cultured rat thyroid monolayer cells is inhibited dose-dependently by methimazole.

We performed monolayer culture of rat thyrocytes and studied gap junctional communication by measuring intercellular fluorescence redistribution after photobleaching. Cell-to-cell communication among thyrocytes gradually developed during the culture. This communication was demonstrated in approximately 60 percent of the cells cultured for 8 days, while it could not be detected in the remaining 40 percent of the cells even after longer culture. When thyrocytes were cultured in the presence of methimazole, the fluorescence recovery after photobleaching was inhibited dose-dependently. Thyroid-stimulating hormone did not affect the fluorescence recovery. We provided, for the first time, that methimazole inhibited the development of cell-to-cell communication of thyrocytes dose-dependently.

Animals↗
PubMed1991

Interferon-gamma inhibits thyroid-stimulating hormone-induced morphological changes and induces the expression of major histocompatibility complex class II antigen in thyroid follicles in suspension culture.

The effects of interferon-gamma (IFN gamma) on the morphology of thyroid follicles and the expression of major histocompatibility complex (MHC) class II antigens were examined. The thyroid follicles were suspended in RPMI-1640 containing 10% fetal calf serum with or without IFN gamma (200 U/ml). After culture for 5 days, follicles were incubated in the presence of TSH (10 mU/ml) for 1 h and fixed for electron microscopic and immunohistochemical examination. Regardless of the presence of IFN gamma, suspended follicles became inverted within 5 days. However, MHC class II antigens were expressed only in inverted follicles cultured with IFN gamma. In inverted follicles cultured without IFN gamma, TSH stimulation induced remarkable morphological changes, such as elongation of microvilli and an appearance of pseudopods. On the other hand, the follicles cultured with IFN gamma showed poor response to TSH. Thus, IFN gamma induced the expression of MHC class II antigens of cultured thyroid follicles and inhibited TSH-induced morphological changes in the cells.

Animals↗
PubMed1991

Human recombinant interleukin 1 inhibits TSH-stimulated morphological changes in thyroid follicles cultured as semi-organs.

To study the effects of human recombinant interleukin-1 on thyrocytes, we cultured thyroid follicles as semi-organs, each consisting of approximately 10-20 follicles, in the presence or absence of IL-1 alpha or beta. Semi-organ culture reproduces the in vivo environment well. After culture for 2 or 4 days, the follicles were incubated with TSH (10 U/l) for 4 h and fixed for light and electron microscopical examinations. Regardless of the presence or absence of IL-1, follicular structure, polarity, and luminal colloid did not change during culture. In thyroid epithelial cells cultured without IL-1, TSH markedly induced elongation of microvilli and formation of reabsorbed colloid droplets. On the other hand, both IL-1 alpha and beta inhibited these TSH-stimulated changes. The degree of inhibition correlated with the concentration of exposure to IL-1. We conclude that IL-1 inhibits TSH-stimulated morphological changes in thyroid follicles cultured as semi-organs, depending on the concentration of IL-1.

Animals↗
PubMed1990

Microcalorimetric studies on metabolism of hepatic tissue. I. A methodological study of normal tissue.

In the present study, the heat production of liver biopsies (5-8 mg) was measured by a microcalorimetric technique. Tissue incubated in Leibowitz L-15 medium (L-15) showed a higher metabolic rate compared to tissue incubated in a medium without substrate 2.8 microW/mg and 1.75 microW/mg, respectively. Heat production was found to be related to weight density. No difference in the metabolic rate was found after organ perfusion in comparison to nonperfused liver. Storage in medium L-15 at 4 degrees C caused a lower rate of heat production, but if the tissue was stored in an electrolyte balance solution without substrate, no difference was seen compared to fresh tissue. Recording heat production with the present calorimetric technique is relatively simple and rapid and allows measurement of small samples.

Animals↗
PubMed1990

Microcalorimetric studies on metabolism of hepatic tissue. II. Measurements of ischemic tissue.

Biopsies of ischemic livers demonstrated a significantly higher rate of heat production when incubated in Leibowitz L-15 medium compared to incubation in modified Eagle's solution (P less than 0.01). A maximal reduction of 25% in the rate of heat production was observed after 60 min of induced ischemia. Liver tissue undergoing reperfusion showed complete and partial recovery after 60 and 90 min, respectively. We conclude that the viability of liver tissue begins to deteriorate after 1-1.5 h of ischemia. Using the level of adenosine triphosphate (ATP) as a parameter for viability, others had found this critical time period to be 1.5-2 h. Furthermore, we conclude that monitoring heat production of tissue provides a useful measure of viability for both clinical application and in connection with experimental liver surgery.

Adenosine Triphosphate↗
PubMed1990

Intranasal immunization of mice with recombinant protein antigen of serotype c Streptococcus mutans and cholera toxin B subunit.

The cholera toxin subunit and the recombinant cell-surface antigen (molecular mass of 190,000 Da) were administered intranasally to BALB/c mice. After 30 days, the mice were immunized intranasally with the recombinant protein antigen alone. High serum IgG and salivary IgA responses to the protein antigen were induced by the intranasal immunization.

Administration, Intranasal↗
PubMed1990

Surface hydrophobicity, adherence, and aggregation of cell surface protein antigen mutants of Streptococcus mutans serotype c.

The pac gene of the serotype c strain Streptococcus mutans MT8148 encodes a cell surface protein antigen (PAc) of approximate 190 kilodaltons. The serotype c strain S. mutans GS-5 does not produce the 190-kilodalton PAc but produces a lower-molecular-weight protein that reacts with anti-PAc serum. The SphI-BamHI fragment of the pac gene was ligated with the S. mutans-Escherichia coli shuttle vector pSA3. The chimeric shuttle vector was transformed into strain GS-5, and two transformants (TK15 and TK18) were isolated. These transformants produced a large amount of cell-free and cell-bound PAc of 190 kilodaltons. No plasmid was isolated from these transformants, and the EcoRI fragments of their chromosomal DNA hybridized with the erythromycin resistance gene in the shuttle vector DNA, indicating insertion of the chimeric shuttle vector DNA into the chromosomal DNA. The cell hydrophobicity of strains TK15 and TK18 as well as PAc-defective mutants constructed by inserting an erythromycin resistance gene into the pac gene of strain MT8148 was analyzed. Strains MT8148, TK15, and TK18 were hydrophobic. On the other hand, strain GS-5 and PAc-defective MT8148 transformants were hydrophilic. Resting cells of the hydrophobic strains attached in larger numbers to saliva-coated hydroxyapatite than did the hydrophilic strains. Human whole saliva induced the aggregation of cells of the hydrophobic strains but not that of cells of the hydrophilic strains. These results suggest that cell surface PAc of S. mutans serotype c participates in attachment of the streptococcal cell to experimental pellicles.

Antigens, Bacterial↗
PubMed1990

Interferon-gamma reduces actin filaments and inhibits thyroid-stimulating hormone-induced formation of microvilli and pseudopods in mouse monolayer thyrocytes.

To study the role of interferon-gamma (IFN gamma), which is released from activated lymphocytes in the development of lymphocytic thyroiditis, we investigated the effects of IFN gamma on the morphology of mouse thyrocytes, using scanning electron microscopy. Thyrocytes were cultured in monolayers for 5-7 days and incubated with TSH (10 mU/ml) for 1 h before fixation. IFN gamma (200 U/ml) was added to the culture medium for 1 h to 5 days before TSH stimulation. Coculture of thyrocytes with IFN gamma for more than 24 h inhibited TSH-induced morphological changes in the thyrocytes; IFN gamma inhibited the increase in the number of and elongation of microvilli and the appearance of pseudopods. IFN gamma also reduced the number of actin filaments in thyrocytes, as confirmed by immunofluorescence photometry. These results suggest that IFN gamma inhibits the morphological response of thyrocytes to TSH stimulation by the reduction of actin filaments.

Actins↗
PubMed1990

[Assessment of cisplatin in concurrent use with radiotherapy in esophageal carcinoma--joint research among nationwide multi-facilities, primary results. Research Committee for Radiation and Cisplatin Treatment of Esophageal Carcinoma].

The effect of cisplatin in concurrent use with radiotherapy for esophageal carcinoma has been assessed as a theme of joint research among nationwide 40 facilities for 18 months from October, 1985, to March, 1987. As the subjects, non-operative cases, recurrent cases and metastatic cases diagnosed as esophageal carcinoma were enrolled. Regimens in 4 kinds were used for treatment and CDDP was used concurrently with radiotherapy in all the regimens. The results of classifying and totalizing the effects in 73 cases, of whom the local effects were analyzed, turned out to be: CR-25 cases, CR rate being 34.2% and PR-33 cases, the effective rate being 79.5%. As a result of aggregating the effects by major axis of X-ray image, CR and effective rates were found as 60 and 90% in the cases with the axes less than 5 cm; 36 and 79% in the cases with axes more than 5 cm and less than 10 cm; and 19 and 76% in the cases with the axes more than 10 cm, all respectively.

Aged↗
PubMed1989

Retarding liver cancer growth in the rat by transient repeated hepatic dearterialization.

The effect of repeated ischemic episodes to experimental liver tumors is studied in a group of inbred Wistar-Furth rats. A vascular occluder model was developed specially for the purpose of delivering intermittent compressions to the hepatic artery in the rat. With five daily 1-hr occlusions of the hepatic artery, rats benefited from significantly reduced tumor growth rates compared with controls that underwent sham operation (P less than 0.05). In contrast to results from previous pig experiments, it is demonstrated by angiographic studies that repeated transient dearterialization does not entirely overcome the problem of collateral vessel formation in the rat. Tumor neovascularization continues irrespective of whether the tumor is being dearterialized. It is also observed that in both normal and tumor rats, collateral channels from the left gastric artery temporarily open up when the hepatic artery is obstructed but disappear on reestablishment of flow. As such types of collateral flow are beyond our control, it is imperative that future developments in vascular occlusion therapy should aim at shortening ischemia time and combining with chemotherapy.

Adenocarcinoma↗
PubMed1989

Effect of subculturing on expression of a cell-surface protein antigen by Streptococcus mutans.

Two freshly isolated strains, Xc and Yc, of Streptococcus mutans serotype c from human dental plaque were subcultured 100 times in Brain Heart Infusion broth. The cell-surface hydrophobicity of strain Xc markedly decreased after subculturing 60 times, but that of strain Yc remained unaltered. Radioimmunoassay showed a close correlation between surface hydrophobicity and the amount of a cell-surface protein antigen (PAc) of Mr 190,000. One hydrophilic variant (strain Xc100L), one relatively hydrophobic variant (strain Xc100H), and two hydrophobic variants (strains Yc100H1 and Yc100H2) were isolated from the 100-fold subcultures of hydrophobic strains Xc and Yc, respectively. SDS-PAGE showed that the amount of cell-associated and cell-free PAc of strain Xc100L was smaller than that of strains Xc and Xc100H. Strain Yc100H2 produced larger amounts of cell-associated PAc than strains Yc and Yc100H1. Resting cells of hydrophilic strain Xc100L attached in smaller numbers to saliva-coated hydroxyapatite than did other hydrophobic strains. RNA dot-blot analysis demonstrated a significant decrease in PAc-specific mRNA in strain Xc100L, as compared with strains Xc and Xc100H. Neither rearrangement nor deletion in the structural gene (pac) for PAc of these strains was observed by Southern blot analysis. These findings suggest that a mechanism which regulates the transcription of the pac gene participates in the quantitative variation of PAc after repeated subculturing.

Antigens, Bacterial↗
PubMed1989

Acute ischemic liver failure in the rat: a reproducible model not requiring portal decompression.

We report a model of acute ischemic liver failure which does not require temporary or permanent portal decompression. The model is induced by segmental ischemia of the median and left lateral lobes for 100 min by a vascular clamp applied on the afferent vessels. Declamping is followed by resection of the nonischemic right lateral and caudate lobes. No portal stasis occurs as blood flow to the right lateral and caudate lobes is maintained during the period of clamping. The 24-hour mortality is 76.5%. Evidence of severe liver damage is shown by histological and biochemical studies.

Acute Disease↗