Kynurenine pathway metabolites in cerebrospinal fluid and serum in complex partial seizures

The kynurenine pathway metabolites, quinolinic acid (QUIN) and L-kynurenine are convulsants, whereas kynurenic acid (KYNA) is an antagonist of excitatory amino acid receptors. Imbalances in the concentrations of these metabolites have been implicated in the etiology of human seizure disorders. In the present study, L-kynurenine and QUIN concentrations in both cerebrospinal fluid (CSF) and serum were reduced in patients with intractable complex partial seizures (CPS) in both the postictal period (15-75 min after a seizure) and the interictal period (absence of seizure for > 24 h) as compared with neurologically normal control subjects. Linear regression analyses and analysis of covariance showed that the reductions in serum QUIN and L-kynurenine were correlated to blood antiepileptic medication. L-Tryptophan (L-TRP) levels also tended to be lower in both CSF and serum of the seizure patients. CSF KYNA and serum 3-hydroxykynurenine concentrations were not affected in seizure patients, whereas serum levels of KYNA were reduced. 3-Hydroxykynurenine was not detected in the CSF of either control or seizure patients. The results do not support a role for a generalized reduction in KYNA concentrations or an increased ratio of QUIN:KYNA, or increases in CSF L-kynurenine in initiation and maintenance of intractable CPS humans.

Atrial natriuretic factor and isosorbide dinitrate modulate the gating of ATP-sensitive K+ channels in cultured vascular smooth muscle cells

The effects of atrial natriuretic factor (ANF) and isosorbide dinitrate (ISDN), activators of particulate and soluble guanylate cyclase, respectively, on K+ currents were investigated in patch-clamp recordings of smooth muscle cells cultured from rat thoracic aorta. In the cell-attached patch configuration, ANF enhanced Ca(2+)-activated K+ (KCa) channel activities as reported previously. When KCa channels were blocked with 1 mmol/L tetraethylammonium or 10(-7) mol/L charybdotoxin, ANF and ISDN applied to the bathing solution activated ATP-sensitive K+ (KATP) channels without altering channel conductance. Pretreatment with methylene blue, a guanylate cyclase inhibitor, abolished the effects of ISDN on KATP channels, whereas 8-bromo-cGMP activated these channels, suggesting that the effects of ISDN on KATP channels were mediated by cGMP. Our results suggest that vasorelaxant agents that increase intracellular cGMP concentrations modulate the gating of two major potassium channels, ATP sensitive and Ca2+ activated, that might play an important role in controlling vascular tone by changing the membrane potential.

Simultaneous determination of benofloxacin, danofloxacin, enrofloxacin and ofloxacin in chicken tissue by high-performance liquid chromatography

A simple, rapid and reliable high-performance liquid chromatographic (HPLC) method for the simultaneous determination of residual fluoroquinolones (benofloxacin, danofloxacin, enrofloxacin and ofloxacin) in chicken has been developed. The drugs were extracted with 0.2% metaphosphoric acid-acetonitrile (7:3, v/v), followed by a Bond Elut C18 clean-up procedure. The HPLC separation was carried out on a Wakosil II 5C18-HG column (150 x 4.6 mm I.D.) with 0.05 M phosphate buffer (pH 2.4)-acetonitrile (80:20, v/v) containing 2.5 mM 1-heptanesulfonic acid as the mobile phase. A fluorescence detector was used at an excitation wavelength of 295 nm and an emission wavelength of 455 nm. The calibration graphs were linear from 0.1 to 10 ng for danofloxacin and from 1 to 100 ng for benofloxacin, enrofloxacin and ofloxacin. The recoveries of the drugs from tissues fortified at a level of 0.2 microgram/g were 81.1-89.6%, and the detection limits were 0.01 microgram/g for ofloxacin, danofloxacin and enrofloxacin and 0.02 microgram/kg for benofloxacin. The time needed per sample was less than 60 min.

Calcium supplementation inhibits the expression of parathyroid hypertensive factor in DOCA-salt hypertensive rats

To elucidate the antihypertensive mechanism of oral calcium supplementation in salt-dependent hypertension, we investigated the hypertensive activity of plasma from DOCA-salt hypertensive rats fed with (DS-Ca) or without (DS) a high calcium diet. Four weeks of calcium supplementation (4% CaCl2) attenuated the blood pressure increase in DS rats. Intravenous bolus injection of dialyzed plasma (1.0-kDa cutoff) from DS rats to normotensive rats resulted in a sustained elevation in blood pressure, whereas that from DS-Ca rats did not. As the endothelin concentration was not different between the two groups, the circulating hypertensive substance in DS rats may be identical to parathyroid hypertensive factor (PHF) and the inhibition of its expression by calcium may be involved in the hypotensive mechanism of high calcium diets in salt-dependent hypertension.

Enzymatic degradation of chitins and partially deacetylated chitins

The enzymatic (lysozyme, chitinase etc.) digestibility of chitins obtained from squid pen and shrimp shell, and of partially deacetylated chitins (DA-chitins) was investigated. The digestibility of various chitins by the chitinase from Bacillus sp. PI-7S was much higher than that by lysozyme, and beta-chitin was digested more smoothly than alpha-chitin. DA-chitin deacetylated under homogeneous conditions (DAC) was hydrolysed by lysozyme more rapidly than that deacetylated under heterogeneous conditions (DAC). DACs from shrimp shell and squid pen showed the same degree of digestibility by lysozyme in spite of a difference in the crystal structure of the original chitins. The crystal structure of chitin and the degree of N-acetyl group aggregation among DA-chitin molecules affect the enzymatic digestibility of chitin and DA-chitin, respectively.

Sarcomatoid carcinoma of the urinary tract

Sarcomatoid carcinoma is a rare variant of malignant tumor arising from the urinary tract. This tumor had been termed carcinosarcoma because of its carcinomatous and sarcomatous components. There is still some confusion in the terminology between true carcinosarcoma and sarcomatoid carcinoma; however, the latter is now regarded as primarily a malignant epithelial tumor with pseudosarcomatous transformation. Four cases of sarcomatoid carcinoma arising from the urinary tract are reported. The patients were a 77 year old female, and three males aged 62, 69 and 80 years. All but the eldest patient complained of gross hematuria. Surgical removal was performed in the younger three cases, and an autopsy was done in the remaining case. All the tumors were macroscopically polypoid. Histopathologic examination revealed fasciculated spindle-cell tumors with myxoid stroma or malignant fibrous histiocytoma-like spindle cell tumors. The epithelial nature was proven in these sarcomatous cells by immunohistochemical and/or electron-microscopic examinations. Only a small amount of squamous cell carcinoma components was also evident in the latter three cases. Although the younger three patients were alive at 44, 23 and 39 months' follow-up, respectively, constant careful monitoring is recommended.

Alpha 1-adrenoceptors in the conduction system of rat hearts

1. We have characterized alpha 1-adrenoceptor in the conduction systems of the rat heart by quantitative autoradiography. 2. Consecutive 20 micron thick sections from a single rat heart containing the sinoatrial (SA) node and atrioventricular (AV) node were incubated with increasing concentrations of [3H]-prazosin with or without 10 microM phentolamine. After exposure to 3H-Ultrofilm, optical densities corresponding to the SA node and AV node were determined by computerized densitometry after comparison with 3H standards. 3. The SA node and AV node were stained heavily for cholinesterase and they contained a higher concentration of alpha 1-adrenoceptors than the adjacent myocardium without a significant change in the affinity. 4. These results support the hypothesis that alpha 1-adrenoceptors may play an important role not only in inotropism but also in chronotropism of rat hearts.

[Studies on cell-mediated immunity (CMI) in the glomeruli: immunization with GBM antigen from Masugi nephritis in Wistar-Kyoto rats]

The role of cell-mediated immunity in glomerular injury has been extensively studied, but the precise mechanism remains obscure. This study was undertaken to determine whether the homologous glomerular basement membrane (GBM) combined heterogeneous anti-GBM antibody would induce cell-mediated immunity. Wistar-Kyoto rats were divided into three groups; group I rats were immunized with homologous GBM antigen that was derived from Masugi nephritis and emulsified in complete Freund's adjuvant (CFA); group II rats were immunized with homologous GBM antigen that was derived from normal rats and emulsified in CFA; group III rats were immunized with CFA only. Group I rats demonstrated proteinuria on days 7 and 10 after immunization. Histologically, mesangial cell proliferation and cell infiltration were observed in the glomeruli. No changes in tubulointerstitial tissue. CD4-positive cells, CD8-positive cells and macrophages were found in the glomeruli, and mononuclear cells were found in the glomerular capillary lumen. Group II and Group III rats demonstrated no proteinuria and no histological changes. These findings indicated that the altered GBM obtained antigenicity and induced cell-mediated immunity in the glomeruli.

Post-transcriptional regulation of the str operon in Escherichia coli. Ribosomal protein S7 inhibits coupled translation of S7 but not its independent translation

The str operon of Escherichia coli consists of the genes for ribosomal proteins S12 (rpsL) and S7 (rpsG) and elongation factors G (fusA) and Tu (tufA). Previous studies have shown that S7 is a translational feedback repressor and inhibits the synthesis of itself and of elongation factor G. We have now shown that induction of S7 synthesis from the S7 gene fused to the arabinose promoter on a plasmid also leads to inhibition of the synthesis of S12 from the chromosomal S12 gene, and that this regulation takes place using the same target site as that used for distal gene regulation, i.e. S7 retroregulates S12. We have then demonstrated that S7 synthesis is mostly translationally coupled with the translation of the preceding S12 gene. Using a rpsG'-'lacZ fusion gene as a reporter for S7 synthesis, we found that abolishing S12 translation by a mutational alteration of the AUG start codon of the S12 gene leads to about tenfold reduction of S7 synthesis without significantly affecting its rate of transcription. Deletion of the proximal portion of the S12 gene or a premature termination of S12 translation by an amber mutation at the 26th codon also led to a large reduction of S7 synthesis. Unexpectedly, we have discovered that overproduction of S7 in trans from a plasmid leads to repression of the rpsG'-'lacZ fusion gene when the fusion gene is preceded by the intact S12 gene, but not when the S12 gene carried the above-mentioned mutations that abolish S12 translation. Thus, a novel feature of this regulatory system is that translation of S7 achieved by independent initiation is not inhibited by S7 in vivo, whereas translation of S7 achieved by translational coupling is sensitive to S7 repression. These observations also suggest that the coupled S7 translation is probably achieved by the use of ribosomal subunits employed for translation of the upstream S12 gene.

Post-transcriptional regulation of the str operon in Escherichia coli. Structural and mutational analysis of the target site for translational repressor S7

In the Escherichia coli str operon, translation of the S12 and S7 genes is largely coupled, and the translational repressor S7 inhibits S7 translation, which is coupled to that of S12, but does not inhibit independent translation of S7 by free ribosomes in the intracellular pool. We have studied the S12-S7 intercistronic region of mRNA by analyzing RNA synthesized in vitro using structure-specific nucleases and a chemical probe, dimethyl sulfate. Based on the results obtained, we have deduced a secondary structure model of the S12-S7 intercistronic region and identified nucleotide residues "protected" by S7. We then carried out site-directed mutagenesis to identify nucleotide residues important for S7 translation as well as for repression by S7. The results showed that two distinct regions are important for S7-mediated repression; one is the S7 binding region identified by the protection analysis and the second is the stem structure that sequesters the Shine-Dalgarno sequence for the S7 gene. Some of the base alterations in the first region abolished S7 binding and, as a consequence, abolished S7-mediated repression, without affecting the efficiency of S7 translation. Other mutations disrupting the stem structure in the second region abolished S7-mediated repression without significantly affecting the S7-mRNA interaction. We also found that certain mutations drastically decrease S7 translation achieved by translational coupling without affecting S7 translation achieved by independent initiation. These mutations are in base-paired regions and evidence was obtained to suggest that these base-paired structures are important for translational coupling. We suggest that some specific RNA structures in the intercistronic region play an active role in achieving translational coupling in this system, and that repression of S7 translation by S7 protein is due to disruption of such structures induced by binding of S7 protein to the target site, rendering translational coupling very inefficient, but leaving independent translation initiation unaffected.

Improved detection of loss of heterozygosity at retinoblastoma gene locus in human breast carcinoma

Loss of heterozygosity (LOH) at the retinoblastoma (Rb) gene locus was investigated in 33 breast carcinomas by polymerase chain reaction single-strand conformation polymorphism (PCR-SSCP) analysis after tumor cell enrichment by cell sorting. The efficacy of cell sorting was evaluated by comparing the results of PCR-SSCP with and without cell sorting. Ten of 17 (59%) informative cases showed LOH at this locus by cell sorting combined with PCR-SSCP, although LOH was detectable in six (35%) cases without cell sorting. Flow cytometry and histologic examination revealed that this underestimation may occur when the tumor cell population is less than 50% in the specimens analyzed. It is concluded that LOH of the Rb gene occurs more frequently in human breast carcinoma than previously thought, and thus may contribute significantly to the development and/or progression of this tumor.

Chronic implantation technique for monopolar EEG monitoring of epileptic seizures in mice

The implanted system was composed of four silver ball electrodes placed in the burr hole of the skull, a reference placed subcutaneously near the nose, two electrodes for EMG, and a ground. The dural attachment was 0.1 mm in diameter. A cassette connector was placed on the back. Implanted cables between the cassette connector and all electrodes consist of twisted fine wires placed in a silicone tube 0.5 mm in diameter. The implanted electrode system weighed 0.8 g. The outlet cables were of the same materials used for implanted cables and placed in a silicone tube 1.5 mm in diameter. The impedance matching between these cables was successful and assured the minimum contamination of artifacts in the EEG recording of freely moving mice. Long-term (4-5 weeks) recording, thus, became possible without damage to the implanted materials. Monopolar recordings demonstrated the localized paroxysmal discharges during general tonic clonic convulsion in El mice. Several artifacts are presented.

[Molecular genetics and biotechnology in medicinal plants: studies by transgenic plants]

The advances in molecular genetics and biotechnology in the field of medicinal plant research are discussed with focusing on the works using transgenic plants. Differentiated organ cultures and transgenic teratomas, incited by the infection with mutants of Agrobacterium Ti and Ri plasmids, were established in quinolizidine-alkaloid producing plants and Solanaceae plants. These cultured cells were used for the production and bioconversion of specific alkaloids produced in these plants. The methods of integration of foreign genes into medicinal plants were developed using an Ri binary vector. The mode of gene expression driven by TR1'-2' promoters was elucidated in transgenic medicinal plants, e.g., Nicotiana tabacum, Glycyrrhiza uralensis, Digitalis purpurea and Atropa belladonna. The genes for herbicide resistance, mammalian cytochrome P450 and bacterial beta-hydroxydecanoylthioester dehydrase were transferred and expressed in plants either to confer herbicide-resistant trait or to change the pattern of metabolites. The cDNA clones encoding cysteine synthase responsible for sulfur assimilation and biosynthesis of non-protein amino acids were isolated and characterized from Spinacea oleracea and Citrullus vulgaris. The functional lysine residue was identified by site-directed mutagenesis experiments. An over-expression system in Escherichia coli was constructed for the bacterial production of the plant specific non-protein amino acids. We made transgenic N. tabacum integrated with sense- and antisense-constructs of cysteine synthase cDNA driven by cauliflower mosaic virus 35S promoter for the purpose of genetic manipulation of biosynthetic flow of cysteine in plants. The future prospects of medicinal plant research are also discussed in the context of modern plant molecular biology.

Effects of vesnarinone (OPC-8212) on Ca(2+)-activated K channels and cytosolic Ca2+ in cultured smooth muscle cells from porcine coronary artery

Vesnarinone is a new, non vasodilating cardiotonic agent. This study compared the effects of vesnarinone and amrinone, a phosphodiesterase (PDE) inhibitors with vasodilating actions, on cultured smooth muscle cells from the porcine coronary artery. Application of vesnarinone (10(-4) M) or amrinone (10(-4) M) to the bath solution in cell-attached patches activated the KCa channel having a conductance of 133 pS (bath 2.7 mM K, pipette 140 mM K). Application of vesnarinone to the cytosolic side had no direct effect on KCa channel activities in inside-out patches. Activation of the KCa channel was suppressed when the intracellular production of cAMP was suppressed by preincubation with carbachol (10(-6) M). Amrinone, but not vesnarinone, lowered [Ca2+]i in the K(+)-depolarized smooth muscle cells (K+ = 70 mM). These results suggest that vesnarinone exerts an additional effect on [Ca2+]i that is independent of PDE inhibition. The difference in the effects on [Ca2+]i in vascular smooth muscle cells may explain in part the differing actions of these agents on vascular relaxation.

Toxicological analysis of drugs and poisons in formalin-fixed organ tissues. 2. Volatile substances

Diethylether, chloroform and toluene were administered by inhalation and ethanol intravenously to rabbits. As soon as possible after death, tissue specimens were collected from the brain, lung, liver, kidney and skeletal muscle and fixed in non-buffered 10% formalin at room temperature (10-20 degrees C) for 4 different periods (1, 2, 5 and 14 days). The volatile substances were analyzed and identified by gas chromatography/mass spectrometry (GC-MS). The measured concentrations of ethanol, diethylether, chloroform and toluene in the brain tissue 1 day after fixation decreased to 8, 23, 73 and 84% respectively compared with those in the non-fixed brain tissue (100%). The rank order of the rate of decrease in the fixed state was: ethanol > diethylether >> chloroform > toluene. These volatile substances could be detected clearly in all the tissue specimens, even after a 14-day fixation period. These results provide useful toxicological information that will help to differentiate whether volatile substances have been administered antemortem or postmortem.

Specificities of IgE, IgG and IgA antibodies to ovalbumin. Comparison of binding activities to denatured ovalbumin or ovalbumin fragments of IgE antibodies with those of IgG or IgA antibodies

We studied the binding activities of IgE, IgG and IgA antibodies in patients with allergy to hen's egg white against two different ovalbumin (OVA) preparations, which were physically or chemically denatured OVA and enzyme-digested OVA fragments. The binding activities of IgE antibodies to these OVA preparations with those of IgG or IgA antibodies were compared. It was found that the binding activities of IgE antibodies to denatured OVA by treatment with dithiothreitol, urea or hydrochloric acid were similar to those of IgG or IgA antibodies. In contrast, the binding activities of IgE antibodies to heat-denatured OVA or by treatment with sodium hydroxide at pH 11.0 were different from those of IgG or IgA antibodies to these denatured OVA. Furthermore, we found that the binding activities of anti-OVA antibodies in sera from patients with allergy to hen's egg white against fragmented OVA were different between IgE antibodies and IgG or IgA antibodies. Thus, it can be concluded that IgE antibodies to OVA in sera from patients with allergy to egg white differ from IgG or IgA antibodies in respect to binding activities against different preparations of denatured or fragmented OVA, probably due to differences in fine specificities of these antibodies against OVA.

Reduction of nonselective adsorption of proteins by hydrophilization of microfiltration membranes by radiation-induced grafting

Alcoholic hydroxyl groups were introduced into a polyethylene microfiltration (MF) membrane by radiation-induced graft polymerization of 2-hydroxyethyl methacrylate (HEMA), vinyl acetate (VAc), and glycidyl methacrylate (GMA). Subsequently, the VAc- and GMA-grafted membranes were quantitatively hydrolyzed into monool (single hydroxyl) and diol groups, respectively. The pure water flux of the modified membrane and the saturation capacity of bovine gamma-globulin onto the membrane were determined as a function of alcoholic hydroxyl group density. The threshold value for hydrophilization ranged between 5 and 7 mol of alcoholic hydroxyl group per kilogram of original MF membrane. Masking of the polyethylene surface with grafted polymer branches containing the diol groups was effective because approximately 70% of the pure water flux of the original MF membrane was maintained. Irrespective of the pore diameter of the original MF membrane, saturation capacities on the modified membrane correlated well with the diol group density. Saturation capacities of bovine gamma-globulin and bovine serum albumin were reduced to 1 mg/m2 of the membrane. In addition, the binding interaction changed from irreversible to reversible.

Intrahepatic peribiliary glands of humans. I. Anatomy, development and presumed functions

The intrahepatic biliary tree is regarded as an excretory duct of two secretory units: hepatocytes and intrahepatic peribiliary glands. This review describes the anatomy, development and presumed functions of the latter. These glands are preferentially located around the intrahepatic large bile ducts, and are histologically divided into intramural and extramural structures. The former consist of simple tubular glands with much mucin, and are sparsely and irregularly distributed within the ductal wall. The latter are characterized by the presence of excretory units that consist of seromucinous acini and a conducting system in the periductal tissue. Pancreatic exocrine acini are occasionally admixed with extramural glands. These peribiliary glands appear in the late fetal period and complete their development about 15 years after birth. Extramural and intramural glands secrete neutral and acid mucin into the ductal lumen. Extramural glands contain several enzymes for digestion of protein and lipids. Neural and vascular supply of these glands may be related to the regulation of their secretion. Specific and non-specific immune responses within this glandular system may also be essential in the sterility of bile.

Quantification of L-tryptophan and L-kynurenine by liquid chromatography/electron capture negative ion chemical ionization mass spectrometry

In a number of infectious and inflammatory diseases, stimulation of the immune system can lead to increased accumulation of tryptophan metabolites via induction of kynurenine pathway enzymes in extrahepatic tissues. We developed a liquid chromatographic/mass spectrometric (LC/MS) method suitable for tracing the disposition of 13C isotopomers of L-tryptophan and L-kynurenine in various cultured cell, tissue slice, and whole animal model systems used to investigate tryptophan flux through the kynurenine pathway. The method employs extractive derivatization of the analytes and their 2H internal standards with pentafluorobenzyl bromide in order to enhance the negative ion chemical ionization (NICI) mass spectrometric response. Normal-phase liquid chromatographic separation of derivatized analytes was optimized using a silica column with organic solvents, followed by particle beam transfer and NICI-MS. Standard curves were linear over the range 1-250 ng per sample. Particle beam and mass spectrometric operating parameters were optimized with direct flow injections of 1-(methylamino) anthraquinone, which is an ideal test compound for the evaluation of LC/NICI-MS. The developed method was used to quantify the conversion of (13C6)L-tryptophan to (13C6)L-kynurenine by human monocytes (THP-1) stimulated with interferon-gamma, lung and brain tissue slices obtained from gerbils immune-stimulated with pokeweed mitogen. The effect of whole body immune stimulation on the plasma levels of endogenous L-kynurenine in mice stimulated with interferon-gamma was also quantified.

Mechanisms of hearing disturbance in an autoimmune model mouse NZB/kl

A subline of the NZB mouse, NZB/kl, was found to develop severe hearing disturbances at high frequency sound at the age of 4 to 6 months. Deposition of IgG was observed on the capillary wall of the stria vascularis of the mice, but the concentration of circulating immune complex did not seem to be correlated to the deposition. Electron microscopic examination revealed that the capillaries had a thick basement membrane, and in severe cases the membrane contained foamy structures of various size. In some cases the base membrane was so thick that the capillary lumen was narrowed, and the intermediate cells seemed to be damaged. No pathological findings were found in other inner ear tissues. These results suggest that the changes in the stria vascularis were possibly caused by an autoimmune mechanism which resulted in hearing disturbance.

Binding of lysozyme onto a cation-exchange microporous membrane containing tentacle-type grafted polymer branches

Ion-exchange adsorption of lysozyme to the sulfonic acid (SO3H) group on polymer chains grafted onto microporous polyethylene hollow-fiber membranes was examined. The lysozyme solution was forced to permeate across the hollow fiber. Diversely anchored SO3H groups, i.e., SP and SS groups, were introduced into the membrane by reaction of the glycidyl methacrylate-grafted membrane with propanesultone and sodium sulfite, respectively. The resulting SP and SS group-containing membranes, designated as SP-T and SS-T fibers, respectively, had 95 and 77% water flux of the original membrane, respectively. The binding capacity of lysozyme as a function of the SO3H group density was compared between the SP-T and SS-T fibers from measurement of the ion-exchange breakthrough curves during the permeation of lysozyme solution across the SP-T and SS-T fibers. The binding capacity of lysozyme to the SP-T fiber remained constant, independent of the SP group density, whereas that to the SS-T fiber increased linearly with increasing SS group density. This difference was explained by means of a model whereby lysozyme adheres onto the SP group-containing grafted polymer branches, while the SS group-containing grafted polymer branches hold lysozyme in a tentacle-like manner.

Hemopneumothorax secondary to multiple cavitary metastasis in angiosarcoma of the scalp

We report a case of hemopneumothorax secondary to multiple cavitary metastasis in the angiosarcoma of the scalp in an 86-year-old woman, who died of respiratory failure. At autopsy, multiple cavities were found in both lungs. Histologic specimen of the cavitary metastasis of the lung showed that tumor cells proliferated forming several tubular spaces and these tubular spaces seemed to communicate with the central cyst. These findings suggested that imperfect vessel-like structures of the cavitary metastasis are likely to break down and finally grow up to large thin-walled cavities.

Thyroglobulin-specific T cell line from a healthy individual does not produce proinflammatory cytokines on antigenic stimulation: an implication for possible fail-safe mechanism to avoid autoimmunity

In order to investigate the regulation of autoimmune response to thyroglobulin (Tg), one of the thyroid autoantigens, we established a Tg-specific T cell line by stimulation of peripheral blood mononuclear cells from a healthy volunteer with Tg and characterized its cytokine production pattern. The Tg-specific T cell line, designated DH5D1, obtained from a limiting dilution culture bore alpha beta T cell receptor and was CD4 and CD45RO positive. Upon stimulation with Tg, DH5D1 secreted little or no titers of IL-2, TNF-alpha, and IFN-gamma, whereas activation with combination of phorbol myristate acetate and calcium ionophore produced measurable levels of these cytokines. These results indicate that the Tg-specific T cell line is not defective in its capacity to produce proinflammatory cytokines and suggest that the inability of cytokine production by autoreactive T cells of healthy individuals is one fail-safe mechanism for preventing aggression of harmful autoimmune response.