Spontaneous lymphocyt ic thyroiditis in interferon regulatory factor-1 deficient non-obese diabetic mice

Interferon regulatory factor-1 (IRF-1) is a transcription factor involved in interferon-mediated immune reaction, CD8+ T cell differentiation and development of T helper 1 immune reaction. We have recently demonstrated that IRF-1 is pivotal in iodine-induced lymphocytic thyroiditis (LT) in non-obese diabetic (NOD) mice. However, it remains unclear whether the mechanism involved in spontaneous LT is identical with iodine-induced LT in NOD mice. To determine the role of IRF-1 in spontaneous LT, we used IRF-1 deficient NOD mice as well as IRF-1 +/+ and +/- mice which were free from treatments for LT induction, and LT was evaluated at 24 weeks of age. IRF-1 +/+, +/- and -/- mice developed LT spontaneously, and there were no differences among the 3 IRF-1 genotypes in the incidence and severity of LT. Whereas both CD4+ and CD8+ T cells were present in the diseased thyroid of IRF-1 +/+ mice, CD8+ T cells were absent in the thyroid of IRF-1 -/- mice. MHC class II antigen expression was induced in the inflamed thyroid of IRF-1 -/- mice comparable to IRF-1 +/+ mice. There was a selective reduction in the number of CD8+ T cells in the spleen of IRF-1 -/- mice. IFNgamma production, but not IL-10, by concanavalin A-stimulated splenocytes was significantly reduced in IRF-1 deficient mice. These results suggest that IRF-1 plays only a minor role in spontaneous LT in NOD mice and, furthermore, the mechanism involved in spontaneous LT is different from that of iodine-induced LT in NOD mice.

Double-stranded RNA-induced interferon regulatory factor-1 gene expression in FRTL-5 rat thyroid cells

Double-stranded RNA (dsRNA) plays a role in the regulation of cell growth and apoptosis as well as in the cellular antiviral responses. However, it remains unknown if dsRNA-activated signaling systems are functional in the thyroid. Here we report the presence of the dsRNA-dependent protein kinase (PKR) in FRTL-5 rat thyroid cells. In poly(I)-poly(C) (pIC)-stimulated cells, activation of nuclear factor-kappa B (NF kappa B) binding was clearly induced. Incubation of FRTL-5 cells with pIC resulted in a marked increase in interferon regulatory factor-1 (IRF-1) mRNA and phosphorylated signal transducer and activator of transcription-1 (STAT1) levels. Addition of pIC to cells led to type I interferon (IFN) gene expression, especially IFN beta, which can induce STAT1 phosphorylation, suggesting that dsRNA indirectly induced STAT1 phosphorylation through expression of type I IFN. Thus, our results suggest that the dsRNA-activated signaling pathway may be involved in the regulation of IFN-inducible genes in the thyroid.

A model of echolocation of multiple targets in 3D space from a single emission

Bats, using frequency-modulated echolocation sounds, can capture a moving target in real 3D space. The process by which they are able to accomplish this, however, is not completely understood. This work offers and analyzes a model for description of one mechanism that may play a role in the echolocation process of real bats. This mechanism allows for the localization of targets in 3D space from the echoes produced by a single emission. It is impossible to locate multiple targets in 3D space by using only the delay time between an emission and the resulting echoes received at two points (i.e., two ears). To locate multiple targets in 3D space requires directional information for each target. The frequency of the spectral notch, which is the frequency corresponding to the minimum of the external ear's transfer function, provides a crucial cue for directional localization. The spectrum of the echoes from nearly equidistant targets includes spectral components of both the interference between the echoes and the interference resulting from the physical process of reception at the external ear. Thus, in order to extract the spectral component associated with the external ear, this component must first be distinguished from the spectral components associated with the interference of echoes from nearly equidistant targets. In the model presented, a computation that consists of the deconvolution of the spectrum is used to extract the external-ear-dependent component in the time domain. This model describes one mechanism that can be used to locate multiple targets in 3D space.

Learning to perceive the world as articulated: an approach for hierarchical learning in sensory-motor systems

This paper describes how agents can learn an internal model of the world structurally by focusing on the problem of behavior-based articulation. We develop an on-line learning scheme-the so-called mixture of recurrent neural net (RNN) experts-in which a set of RNN modules become self-organized as experts on multiple levels, in order to account for the different categories of sensory-motor flow which the robot experiences. Autonomous switching of activated modules in the lower level actually represents the articulation of the sensory-motor flow. In the meantime, a set of RNNs in the higher level competes to learn the sequences of module switching in the lower level, by which articulation at a further, more abstract level can be achieved. The proposed scheme was examined through simulation experiments involving the navigation learning problem. Our dynamical system analysis clarified the mechanism of the articulation. The possible correspondence between the articulation mechanism and the attention switching mechanism in thalamo-cortical loops is also discussed.

Measurement of red blood cell zinc concentration with Zn-test kit: discrimination between hyperthyroid Graves' disease and transient thyrotoxicosis

We have previously reported in patients with hyperthyroidism that the red blood cell (RBC) zinc (Zn) concentration reflects the mean thyroid hormone concentration over the preceding months. In the present study, the concentration of RBC Zn was measured by a simple and easy method with a Zn-test Wako kit. Within-run and between-run precision were 1.4% and 1.3%, respectively. The relationship between RBC concentration and dilution was linear. The average recovery was 103%. A good correlation (r=0.97) was obtained between this method and atomic absorption spectrophotometry. The mean concentration of RBC Zn in 39 euthyroid controls was 12.6 +/- 1.3 mg/l, ranging from 10.4 to 15.1 mg/l. The RBC Zn concentrations in 38 patients with Graves' disease, in 10 patients with silent thyroiditis and in 3 patients with gestational thyrotoxicosis were 7.3 +/- 1.6 (3.2-9.8), 12.0 +/- 1.6 (9.5-14.2) and 11.8 +/- 1.7 (10.5-13.7) mg/l, respectively. The concentration of RBC Zn was able to differentiate hyperthyroid Graves' disease from transient thyrotoxicosis except in 1 case and was a better index than TSH-binding inhibitory immunoglobulin. These results indicate that measuring RBC Zn with the Zinc-test Wako kit is very useful in differentiating hyperthyroid Graves' disease from transient thyrotoxicosis.

Hyperthyroid Graves' disease and primary hypothyroidism caused by TSH receptor antibodies in monozygotic twins: case reports

A 33-year-old woman with signs and symptoms of hypothyroidism, including increased thyroid stimulating blocking antibody (TSBAb) activity, was referred for treatment by her local physician. Her monozygote twin was treated for hyperthyroid Graves' disease 10 years earlier. This case of hyperthyroidism and hypothyroidism in identical twins suggests the involvement of environmental factors in the pathogenesis of autoimmune thyroid diseases.

Role of thyroid-stimulating blocking antibody in patients who developed hypothyroidism within one year after 131I treatment for Graves' disease

OBJECTIVE

We recently reported that thyroid-stimulating blocking antibody (TSBAb) may not contribute to the development of hypothyroidism more than six years after 131I treatment. In the present study, we attempted to determine whether hypothyroidism that develops within a shorter period of time following 131I therapy is associated with TSBAb.

DESIGN

Retrospective study.

PATIENTS

Sera were obtained from 8 patients who developed hypothyroidism within 6 months after 131I therapy (Group 1), 8 patients who became euthyroid one year after 131I therapy (Group 2), and 7 patients who developed transient hypothyroidism (Group 3).

MEASUREMENTS

Thyroid stimulating antibody (TSAb) activity was measured as the amount of cyclic adenosine monophosphate (cAMP) produced by cultured FRTL-5 cells, and TSBAb activity as the inhibition of cAMP produced in response to 100 mU/l bovine TSH.

RESULTS

At about 3 months after 131I treatment, TSAb activity increased significantly in Groups 2 and 3, but did not change in Group 1. In contrast, TSBAb activity in Group 1 increased significantly and was positive in 6 patients at that time. At 12-18 months after 131I treatment, TSBAb activity tended to decrease and remained positive in 3 patients but became negative in 3 patients. It did not change in the patients in Groups 2 and 3. The patients in Group 1 were treated with levothyroxine, 75-125 micrograms/day. Levothyroxine was discontinued in the 3 patients whose TSBAb activity disappeared. Two of them remained euthyroid, and 1 became hypothyroid.

CONCLUSION

Results indicate that the hypothyroidism that develops within a short time after 131I treatment may be caused by TSBAb activity. Thyroid function may be recovered when TSBAb activity disappears.

Effects of ethanol on the levels of brain 6R-L-erythro-5, 6, 7, 8-tetrahydrobiopterin in the inbred strains of mice. DBA/2J, C3H/HeJ and C57BL/6J with different alcohol preferences

6R-L-erythro-5, 6, 7, 8-tetrahydrobiopterin (6R-BH4) is a coenzyme for tyrosine, tryptophan and phenylalanine hydroxylases, the former two of which are the initial and the rate-limiting enzymes in the biosynthesis of the catecholamines and serotonin, respectively. The present study was designed to determine the changes in concentrations of 6R-BH4 in striatum and midbrain of the inbred strains of mice, DBA/2J, C3H/HeJ and C57BL/6J, with different genetically determined alcohol preferences, following the injection of ethanol (EtOH). The intraperitoneal administration of EtOH (0, 1, 2 and 4 g/kg) significantly and dose-dependently reduced the levels of striatal and midbrain 6R-BH4 in DBA/2J mice with the lowest alcohol preference, and EtOH (4 g/kg, i.p.) reduced the level of striatal 6R-BH4 in C3H/HeJ with medium alcohol preference. Following the administration of EtOH (4 g/kg, i.p.), brain 6R-BH4 levels in C57BL/6J mice with high alcohol preference were lowered compared with the control group, but the difference did not reach statistic significance. EtOH has a tendency to reduce the brain 6R-BH4 levels in mice with lower alcohol preference or higher sensitivity to EtOH. Based on these findings, it was proposed that differences in alcohol drinking behavior in the inbred strains of mice was influenced by brain 6R-BH4.

Effects of ion channel blockers on rapid postmortem changes in extracellular dopamine and serotonin levels in the rat nucleus accumbens

In the present study, we used in vivo brain microdialysis to examine the effects of ion channel blockers tetrodotoxin (TTX), EGTA-free Ca2+ and verapamil on rapid postmortem changes in extracellular levels of dopamine (DA), serotonin (5-HT) and their metabolites dihydroxyphenylacetic acid (DOPAC) and 5-hydroxyindoleacetic acid (5-HIAA) in the ACC of freely moving rats. Extracellular ACC DA levels decreased following the perfusion of the three ion channel blockers in freely moving rats, and then, at death by cervical dislocation, maximum respective 220-, 60- and 90-fold increases were observed in the extracellular output of DA in animals treated with EGTA, verapamil and TTX, respectively. Also, ACC 5-HT decreased following perfusion with the three blockers in the freely moving rats, and then maximum increases of 80-, 30- and 45-fold in the extracellular output of 5-HT were observed at death in animals treated with EGTA, verapamil and TTX, respectively, compared to the baseline. Cervical dislocation-induced rapid postmortem changes were inhibited markedly by perfusion with CSF containing the CA2+ entry blocker verapamil. These observations suggested that rapid postmortem changes in ACC DA and 5-HT release were associated with the action of calcium ion channels and/or voltage gated channels in the CNS.

Possibility of 5-HT3 receptor involvement in alcohol dependence: a microdialysis study of nucleus accumbens dopamine and serotonin release in rats with chronic alcohol consumption

The present study was performed to examine the involvement of serotonin-3 (5-HT3) receptors in the rat nucleus accumbens (ACC) in alcohol dependence. In alcohol-treated rats, perfusion of 40 mM K+ and 100 mM ethanol (EtOH) through the microdialysis probe increased the extracellular levels of ACC dopamine (DA), compared with controls. Perfusion of the serotonin (5-HT) uptake inhibitor sertlarine enhanced the extracellular levels of ACC 5-HT in both groups. Increased 5-HT availability in the synaptic clefts on the ACC further activated ACC DA release in the alcohol-treated rats, in comparison with controls. In the final experiments, perfusion of the 5.0 microM 5-HT3 receptor agonist 2-methyl-5-HT (2-Me-5-HT) through the microdialysis probe enhanced the extracellular levels of ACC DA. Magnitude of 2-Me-5-HT-induced DA release was significantly higher in alcohol-treated rats than in controls. On the other hand, 40 mM K(+)- and 100 mM EtOH-induced extracellular 5-HT release in alcohol-treated rats were markedly inhibited. These results show that (1) chronic alcohol intake increases the sensitivity of 5-HT3 receptors, (2) 5-HT3 receptors regulate DA release in the ACC, (3) the dopaminergic neuronal systems associated with 5-HT3 ionophore in the ACC were upregulated after chronic alcohol exposure, and (4) chronic alcohol intake desensitizes the serotonergic neuronal systems in rat ACC. These findings suggest that neurochemical functions of 5-HT3 receptors in regulating DA release in the ACC after alcohol exposure compensate for the dysfunction of serotonergic activity to restore the original properties in processing alcohol tolerance and that the development of alcohol dependence may be mediated by ACC 5-HT3 receptors.

Increased regional systolic myocardial stiffness of the left ventricle during coronary artery occlusion in a dog: analysis of the finite element model

(1) We measured the instantaneous systolic transfer function of an isolated canine left ventricle (LV) before and after the ligation of the left anterior descending coronary artery (LAD). The instantaneous transfer function before the ligation of the LAD showed a resonance curve whose peak frequency was 30 to 70 Hz. On the other hand, the transfer function 40 min after the ligation of the LAD showed a divided peak in the resonance curve. (2) We constructed a finite element model of a thick-walled spherical shell with a non-uniform structure. In this model, the myocardial elasticity and viscosity of the ischemic region are different from those of non-ischemic regions. One can calculate the theoretical transfer function using modal analysis and also estimate the elasticity and the viscous coefficient of both non-ischemic and ischemic myocardium by fitting the theoretical transfer function to the experimental one. (3) The estimated elasticity of the ischemic myocardium was three to five times larger than that of the non-ischemic myocardium. The estimated viscous coefficient of the ischemic myocardium was about half that of the non-ischemic myocardium. These results showed that ischemia alters the viscoelastic properties of the myocardium during systole as well as during diastole.

Simulation study on heart failure: effects of contractility on cardiac function

Using the model proposed by Beyar and Sideman, the effect of maximum isometric active stress at optimal sarcomere length (sigma 0) on left ventricular (LV) function was examined. Comparing the results of calculated LV function with those of reported experiments, sigma 0 was shown to be a potential indicator of myocardial contractility, and the model of Beyar and Sideman successfully predicted LV function with various myocardial contractilities. The LVP compensation curve, which describes the relationship between sigma 0 and maximum LV pressure, was then hypothesized. The combination of the Beyar-Sideman model and the LVP compensation curve enabled the prediction and approximation of the actual process of deterioration in heart failure. These models represent a step towards a fundamentally new concept in the current clinical situation of compensated heart failure and also in evaluating the process of heart failure.

Simulation study on the effect of external vibration on left ventricular function: potential indicator of LV tolerance to the sudden reduction of myocardial contractility

In a previous study the authors reported that external mechanical vibration applied to the left ventricular (LV) epicardium induces contractility-dependent depression in LV pressure, stroke volume and stroke work. It was suggested that this depression may be caused by the direct effect of external vibration on contractile protein. In another paper in this issue, it is proved that LV function with various myocardial contractilities and the actual process of deterioration in heart failure are well simulated in the model proposed by Beyar and Sideman, after some modifications have been made. In the study reported here it is assumed that an external mechanical vibration induces sudden reduction in myocardial active stress in the model of Beyar and Sideman; in this way the contractility-dependent effect of external vibration on LV function has been simulated. The results of this simulation support the suggestion that external mechanical vibration directly affects contractile protein and reduces LV function, and it is further suggested that the reduction of LV function induced by external vibration reflects the reserve or tolerance capacity of LV to a sudden reduction of myocardial contractility.

Estimation of left ventricular myocardial elasticity and viscosity by a thick-walled spherical model

The authors measured the transfer function (TF) of the left ventricle (LV) in an isolated canine preparation. Here TF indicates the ratio of induced vibration in LV to input vibration when an external mechanical oscillation is applied. TF had a single peak the frequency of which changed from 40 Hz to 80 Hz when LV pressure (LVP) increased from 6 mm Hg to 96 mm Hg. A mathematical model was formulated to estimate the viscoelasticity of the spherical shell. This model was constructed of the material points, elastic components which connected all the material points, and viscous components placed in series with elastic components. Theoretical TF can be computed if the viscoelastic values are given. The value of viscoelasticity at which the theoretical TF best fitted the experimental TF was considered to be the viscoelasticity of the model. The validity of this approach was verified using a silicone spherical shell. The estimated myocardial elasticity was 40 kPa when LVP was 6 mm Hg, 160-170 kPa when LVP was 96 mm Hg and was approximately proportional to LVP, whereas viscosity showed small change. The inclination of elasticity was consistent with previous reports. These results proved that myocardial elasticity can be estimated by analysing the transfer function of the left ventricle.

[Microdensitometric study of maturation and fragility of the bone in male patients with cerebral palsy--the effect of long-term administration of 1 alpha-hydroxy vitamin D3 and the value of osteocalcin as a marker of bony growth]

1) We studied bony maturation and fragility in 48 male patients (4-28 years old) with cerebral palsy. They were divided into three groups; group A (drug free, mild motor handicapped), 10 cases, group B (anticonvulsants administrated, mild motor handicapped), 20 cases, group C (anticonvulsants administrated, severe motor handicapped) 18 cases. The indicator of bone mineral content (sigma GS/D) and metacarpal index (MCI) were analyzed by microdensitometric method. A positive correlation between age and sigma GS/D was detected in all groups but a positive correlation between age and MCI was found only in the group B. There was little difference in sigma GS/D and MIC between group A and group B, but those of group C were significantly decreased. These results suggest that increase of bone mineral is related with aging but metacarpal growth is variable, and a lack of daily activity has greater adverse effect on bony metabolism than administration of anticonvulsants. 2) The alterative rates of sigma GS/D (delta sigma GS/D/sigma GS/D/year) and MCI (delta MCI/MCI/year) after 1 alpha-hydroxy vitamin D3 (D3) treatment for 3 years or more were examined in 17 patients with bony atrophy, as compared with normal controls. The alterative rates of sigma GS/D and MCI were elevated in younger patients with D3 treatment but those were decreased in adult patients. Treatment with D3 remarkably increased bony growth in children. 3) In 37 patients, osteocalcin (OC) was measured by radioimmunoassay. OC was elevated in younger patients who were treated with D3.(ABSTRACT TRUNCATED AT 250 WORDS)

[Pituitary reserve of growth hormone in adolescent patients with cerebral palsy and mental retardation]

The pituitary reserve of growth hormone (GH) was studied in 11 severely handicapped boys (14 approximately 18 years old) with mental retardation and cerebral palsy (CP); athetotic type 4 cases, and spastic type 7 cases. Serum GH was determined before and after intravenous injection of 1 ng/kg growth hormone releasing factor (GRF) or oral administration of 0.1 mg/m2 clonidine. The athetotic type patients showed low somatomedin C (Sm C) concentrations (0.31 +/- 0.11 U/ml), poor responses to clonidine, and good responses to GRF. The spastic type patients showed subnormal responses to GRF although their Sm C was normal (0.91 +/- 0.43 U/ml). Clinically, the stature was small, and the puberty was delayed in the former. The levels of plasma testosterone were significantly lower than those in the latter. It is concluded that athetotic type CP was associated with hypothalamic GRF deficiency and spastic type CP was associated with reduced pituitary reserve of GH.