The forkhead transcription factors, Foxp1 and Foxp2, identify different subpopulations of projection neurons in the mouse cerebral cortex.

Foxp1 and Foxp2, which belong to the forkhead transcription factor family, are expressed in the developing and adult mouse brain, including the striatum, thalamus, and cerebral cortex. Recent reports suggest that FOXP1 and FOXP2 are involved in the development of speech and language in humans. Although both Foxp1 and Foxp2 are expressed in the neural circuits that mediate speech and language, including the corticostriatal circuit, the functions of Foxp1 and Foxp2 in the cerebral cortex remain unclear. To gain insight into the functions of Foxp1 and Foxp2 in the cerebral cortex, we characterized Foxp1- and Foxp2-expressing cells in postnatal and adult mice using immunohistochemistry. In adult mice, Foxp1 was expressed in neurons of layers III-VIa in the neocortex, whereas the expression of Foxp2 was restricted to dopamine and cyclic adenosine 3',5'-monophosphate-regulated phosphoprotein, 32 kDa (DARPP-32)(+) neurons of layer VI. In addition, Foxp2 was weakly expressed in the neurons of layer V of the motor cortex and hindlimb and forelimb regions of the primary somatosensory cortex. Both Foxp1 and Foxp2 were expressed in the ionotropic glutamate receptor (GluR) 2/3(+) neurons, and colocalized with none of GluR1, gamma-aminobutyric acid, calbindin, and parvalbumin, indicating that expression of Foxp1 and Foxp2 is restricted to projection neurons. During the postnatal stages, Foxp1 was predominantly expressed in Satb2(+)/Ctip2(-) corticocortical projection neurons of layers III-V and in Tbr1(+) corticothalamic projection neurons of layer VIa. Although Foxp2 was also expressed in Tbr1(+) corticothalamic projection neurons of layer VI, no colocalization of Foxp1 with Foxp2 was observed from postnatal day (P) 0 to P7. These findings suggest that Foxp1 and Foxp2 may be involved in the development of different cortical projection neurons during the early postnatal stages in addition to the establishment and maintenance of different cortical circuits from the late postnatal stage to adulthood.

Characterization of Foxp2-expressing cells in the developing spinal cord.

Two members of winged-helix/forkhead transcription factors, Foxp1 and Foxp2, are expressed in the developing and adult CNS, including the striatum, cerebral cortex, and thalamus. In a previous study, we have demonstrated that Foxp1 is expressed in a subpopulation of V1 interneurons in addition to motor neurons of the spinal cord during mouse embryogenesis. However, the detailed expression pattern of Foxp2 and its relationship with Foxp1 in the developing spinal cord remains to be elucidated. To shed light on the potential roles of Foxp1 and Foxp2 in the developing spinal cord, we characterized Foxp2-expressing cells during mouse embryogenesis. At embryonic day (E) 11.0, Foxp2-expressing cells were first observed in the ventral spinal cord, which were Pax6(-), p27(+), and neuron-specific class III beta-tubulin(+) postmitotic neurons. Between E13.5 and E15.5, high expression of Foxp2 was observed in both medial and lateral parts of the ventral spinal cord. Double-immunofluorescence staining for Foxp2 with some homeodomain transcription factors revealed that Foxp2-expressing neurons were Pax2(+), En1(+), Evx1(-), Chx10(-), Gata3(-), and Lhx3(-) V1 interneurons in the intermediate zone throughout the ventral spinal cord, indicating that Foxp2-expressing neurons were also V1 interneurons with the same phenotypes as Foxp1-expressing interneurons. In addition, neither Foxp1 nor Foxp2 was expressed in ventral calbindin(+) Renshaw cells. However, Foxp2 did not colocalize with Foxp1 in interneurons of the ventral spinal cord. These findings suggest that Foxp1 and Foxp2 are expressed in the distinct subsets of V1 interneurons that belong to non-Renshaw cells in the ventral spinal cord during embryogenesis. Thus, Foxp1 and Foxp2 may be involved in the determination of the cell type identities during late embryogenesis: the classes of neurotransmitters and the functional subtypes of non-Renshaw cells, such as Ia and Ib inhibitory interneurons.

Expression of mKirre in the developing sensory pathways: its close apposition to nephrin-expressing cells.

mKirre is a novel member of the immunoglobulin superfamily, which is abundant in the developing and adult brain. In the present study, we showed mKirre gene expression in mouse sensory organs during development using in situ hybridization and immunohistochemistry. At embryonic day (E) 11.5, E15.5, and E17.5, we first detected signals for mKirre mRNA in the developing cochleae, retinae, and olfactory neuroepithelia, respectively. After birth, strong signals were observed in these sensory organs. In addition, at this stage, we found its expression in trigeminal ganglion neurons and neuronal populations forming sensory pathways in the olfactory bulb, midbrain, and pons. Furthermore, double-immunofluorescence staining revealed that nephrin-immunoreactivity was overlapping to mKirre-expressing cells in the developing sensory organs. These results suggest that mKirre may be involved in the establishment of the pathway from sensory organs to the brain not only in a homophilic manner but also with its heterophilic interaction to nephrin.

The Tokyo subway sarin attack--lessons learned.

The sarin gas attack in the Tokyo subway system is reviewed from a clinical toxicology perspective. Based on the lessons learned from this attack, the following areas should be addressed on a global scale. First, an adequate supply of protective equipment is required, including level B protective equipment with a pressure demand breathing apparatus. In addition, a system should be established that enables a possible cause to be determined based on symptoms, physical findings, general laboratory tests, and a simple qualitative analysis for poisonous substances. If an antidote is needed, the system should enable it to be administered to the victims as quickly as possible. Preparation for a large-scale chemical attack by terrorists requires the prior establishment of a detailed decontamination plan that utilizes not only mass decontamination facilities but also public facilities in the area. A system should be established for summarizing, evaluating, and disseminating information on poisonous substances. Finally, a large-scale scientific investigation of the Tokyo sarin attack should be conducted to examine its long-term and subclinical effects and the effects of exposure to asymptomatic low levels of sarin.

Expression of mKirre, a mammalian homolog of Drosophila kirre, in the developing and adult mouse brain.

mKirre, a mammalian homolog of the Drosophila kirre, is expressed in bone marrow stromal cells and the brain. Although mKirre has been shown to support the hematopoietic stem cells, little is known about the function of mKirre in the brain. In the present study, to gain insights into the function of mKirre, we investigated the expression pattern of mKirre gene in the developing and adult mouse brain using in situ hybridization. In the adult brain, mKirre mRNA was highly expressed in the olfactory bulb, the piriform cortex, the cochlear nucleus, and the cerebellum. At embryonic day (E) 11.5, we could observe mKirre mRNA in the differentiating zones of various regions, such as the caudate-putamen, the geniculate body, the thalamus, the amygdala, and the brainstem. Its gene expression in these regions at E11.5 also persisted to the adult, in which its expression levels were much less prominent. After birth, we could first observe high expression of mKirre mRNA in the glomerular and mitral layers of the olfactory bulb, the cortical plate of the neocortex, the cochlear nucleus, and the molecular and granule cell layers of the cerebellum. In the hippocampus, its gene expression was first observed in the dentate gyrus at postnatal day 7. The spatiotemporal expression pattern of mKirre mRNA suggests important roles of mKirre in later developmental processes, especially the synapse formation.

Foxp1 gene expression in projection neurons of the mouse striatum.

The developmental processes of maturation in the CNS are the result of specific events including mitogenesis, differentiation, and cell death which occur in a precise spatial and temporal manner. It has been reported that many transcription factors, including forkhead transcription factors, play a key role in these processes. First, we examined the expression pattern of the forkhead transcription factor Foxp1 in the adult CNS. Foxp1 was highly expressed in the striatum and moderately in the cerebral cortex, CA1/2 subfields of the hippocampus, and several thalamic nuclei. In situ hybridization combined with immunohistochemistry in the striatum of adult mice revealed that Foxp1 mRNA was detected in a subset of projection neurons, not in interneurons. In addition, the expression of Foxp1 mRNA was observed in the developing basal ganglia with the exception of the globus pallidus. Thus, Foxp1 mRNA was expressed in a subset of striatal projection neurons, probably the matrix neurons. The expression pattern of Foxp1 mRNA suggests that Foxp1 may play a role in the development and formation of a circuit in the basal ganglia, which is involving the matrix neurons.

Enhancement of Rho/Rho-kinase system in regulation of vascular smooth muscle contraction in tachycardia-induced heart failure.

OBJECTIVE: The Rho/Rho-kinase system regulates Ca(2+) sensitivity in vascular smooth muscle. A new drug, Y-27632, specifically inhibits Rho-kinase and hence decreases the phosphorylation of myosin light chain, thus reducing contraction. Here, we compare the effects of Y-27632 and nifedipine on the vasoconstrictor response of the femoral artery in heart failure. METHODS: Heart failure (HF) was produced by chronic rapid RV pacing (250 bpm, 28 days, six dogs). Indo1-AM was loaded into endothelium-denuded femoral artery segments for measuring intracellular [Ca(2+)]. Tension and changes in intracellular [Ca(2+)] [the change in the ratio (418 nm/468 nm) of Indo1 fluorescence (F(ratio))] were simultaneously measured in Krebs-Ringer solution. RESULTS: In HF: (i) norepinephrine (10 microM) produced greater tension (784+/-52 g/cm(2)) than in control (502+/-64 g/cm(2)) despite a similar increase in F(ratio), indicating increased Ca(2+) sensitivity in vascular smooth muscle; (ii) nifedipine attenuated this enhanced response by only a maximum of 27% at 1 micromol/l with a 56% reduction in F(ratio); (iii) Y-27632 attenuated it by a maximum of 80% at 100 micromol/l without a significant change in F(ratio); (iv) RhoA protein and mRNA expression levels in the femoral artery were up-regulated by +110% and +56%, respectively, while those of Rho-kinase were unchanged. CONCLUSIONS: The Ca(2+)-sensitizing mechanism involving the Rho/Rho-kinase system may be deeply involved in the enhanced arterial vasoconstriction seen in HF. Since Y-27632 attenuated this response in small arteries, it shows potential as a novel, potent vasodilator for the treatment of HF.

Altered stoichiometry of FKBP12.6 versus ryanodine receptor as a cause of abnormal Ca(2+) leak through ryanodine receptor in heart failure.

BACKGROUND: In the pathogenesis of cardiac dysfunction in heart failure, a decrease in the activity of the sarcoplasmic reticulum (SR) Ca(2+)-ATPase is believed to be a major determinant. Here, we report a novel mechanism of cardiac dysfunction revealed by assessing the functional interaction of FK506-binding protein (FKBP12.6) with the cardiac ryanodine receptor (RyR) in a canine model of pacing-induced heart failure. METHODS AND RESULTS: SR vesicles were isolated from left ventricular muscles (normal and heart failure). The stoichiometry of FKBP12.6 per RyR was significantly decreased in failing SR, as assessed by the ratio of the B(max) values for [(3)H]dihydro-FK506 to those for [(3)H]ryanodine binding. In normal SR, the molar ratio was 3.6 ( approximately 1 FKBP12.6 for each RyR monomer), whereas it was 1.6 in failing SR. In normal SR, FK506 caused a dose-dependent Ca(2+) leak that showed a close parallelism with the conformational change in RyR. In failing SR, a prominent Ca(2+) leak was observed even in the absence of FK506, and FK506 produced little or no further increase in Ca(2+) leak and only a slight conformational change in RyR. The level of protein expression of FKBP12.6 was indeed found to be significantly decreased in failing SR. CONCLUSIONS: An abnormal Ca(2+) leak through the RyR is present in heart failure, and this leak is presumably caused by a partial loss of RyR-bound FKBP12.6 and the resultant conformational change in RyR. This abnormal Ca(2+) leak might possibly cause Ca(2+) overload and consequent diastolic dysfunction, as well as systolic dysfunction.

Altered interaction of FKBP12.6 with ryanodine receptor as a cause of abnormal Ca(2+) release in heart failure.

OBJECTIVE: Little information is available as to the Ca(2+) release function of the sarcoplasmic reticulum (SR) in heart failure. We assessed whether the alteration in this function in heart failure is related to a change in the role of FK binding protein (FKBP), which is tightly coupled with the cardiac ryanodine receptor (RyR) and recently identified as a modulatory protein acting to stabilize the gating function of RyR. METHODS: SR vesicles were isolated from dog LV muscles [normal (N), n=6; heart failure induced by 3-weeks pacing (HF), n=6]. The time course of the SR Ca(2+) release was continuously monitored using a stopped-flow apparatus, and [3H]ryanodine-binding and [3H]dihydro-FK506-binding assays were also performed. RESULTS: FK506, which specifically binds to FKBP12.6 and dissociates it from RyR, decreased the polylysine-induced enhancement of [3H]ryanodine-binding by 38% in N (P<0.05) but it had no effect in HF. In HF, the rate constant for the polylysine-induced Ca(2+) release from the SR was 61% smaller than in N. FK506 decreased the rate constant for the polylysine-induced Ca(2+) release by 67% in N (P<0.05) but had no effect in HF. The [3H]dihydro-FK506-binding assay revealed that the number (B(max)) of FKBPs was decreased by 83% in HF (P<0.05), while the K(d) value was unchanged. FK506 did not significantly change SR Ca(2+.)-ATPase activity in either N or HF. CONCLUSIONS: In HF, the number of FKBPs showed a tremendous decrease; this may underlie the RyR-channel instability and the impairment of the Ca(2+) release function of RyR seen in the failing heart.

Effect of milrinone on left ventricular relaxation and Ca(2+) uptake function of cardiac sarcoplasmic reticulum.

Milrinone, a phosphodiesterase 3 (PDE3) inhibitor, is known to enhance left ventricular (LV) contractility by an inhibition of the breakdown of cAMP through the mechanism inhibiting PDE3. However, it is unclear whether milrinone also exerts positive lusitropy, like dobutamine. Here, we assessed the effects of milrinone on in vivo LV relaxation, as well as the Ca(2+)-ATPase activity and the Ca(2+) uptake function of the cardiac sarcoplasmic reticulum (SR), compared with the effect of dobutamine on those functions. After dobutamine (3 microg x kg(-1) x min(-1)) was administered, the peak value of the first derivative of LV pressure (+dP/dt) increased by 46%, whereas the time constant (tau) of LV pressure decay decreased by 6.9%, respectively. After milrinone (10 microg/kg) was administered, the peak +dP/dt increased to a similar extent as dobutamine (46%), whereas tau decreased much more than dobutamine (19.9%; P < 0.05). In LV crude homogenate, the thapsigargin-sensitive, Ca(2+)-ATPase activity-cAMP relationships was significantly less increased by milrinone compared with dobutamine (P < 0.05), indicating the higher sensitivity of the SR Ca(2+)-ATPase activity on cAMP by milrinone than by dobutamine. In the SR vesicles purified from LV muscles, the addition of cAMP increased the SR Ca(2+) uptake in a dose-dependent fashion, and the PDE3 inhibitors (milrinone and cGMP) significantly augmented this response (P < 0.05). Hence, milrinone substantially improved LV relaxation in association with an acceleration of the SR Ca(2+)-ATPase activity and the SR Ca(2+) uptake. This acceleration might be due to an inhibition of the membrane-bound PDE3 in the SR, leading to a local elevation of cAMP.

Mechanism of preserved positive lusitropy by cAMP-dependent drugs in heart failure.

In tachycardia-induced heart failure (HF), positive lusitropic effects of milrinone or dobutamine were assessed by evaluating the time constant of left ventricular (LV) pressure decay (tau) and Ca(2+)-ATPase activity of the sarcoplasmic reticulum (SR). The peak value of the positive first derivative of LV pressure (+dP/dt) was less increased, either by dobutamine (2-10 microg x kg(-1) x min(-1)) or by milrinone (4-20 microg/kg), in HF than in control (P < 0.05), whereas tau was shortened to an extent similar to that in control with dobutamine [P = not significant (NS)] and to an even greater extent with milrinone (P < 0.05). Ca(2+)-ATPase activity increased similarly in HF and control with dobutamine (1 microM; +11% in HF vs. +12% in control, P = NS), whereas it increased more with milrinone (1 microM; +19% in HF vs. +11% in control, P < 0.05). Ca(2+)-ATPase activity-cAMP relationships were shifted to the left by milrinone or dobutamine in HF compared with control. Thus, in HF, the sensitivity of Ca(2+)-ATPase activity to cAMP was increased on addition of cAMP-dependent inotropic agents, contributing to the preservation of positive lusitropy.

Abnormal Ca2+ release from cardiac sarcoplasmic reticulum in tachycardia-induced heart failure.

OBJECTIVE: In heart failure, little information is available as to the Ca2+ release function of sarcoplasmic reticulum (SR), which plays a major role in cardiac contractile function. Here, we assessed the rapid kinetics of drug-induced Ca2+ release from cardiac SR in combination with a measurement of ryanodine binding in heart failure. METHODS: The SR vesicles were isolated from dog left ventricular (LV) muscles (normal (N), n = 10; pacing induced heart failure (HF), n = 10). The time course of SR Ca2+ release was continuously monitored by a stopped-flow apparatus using arsenazoIII as a Ca2+ indicator, and Ca2+ uptake and [3H]ryanodine binding assays were done using a filtration method. RESULTS: The amount of Ca2+ uptake was reduced in HF to 55% of N (P < 0.05). Even the more marked and earlier appeared decrease was seen in the rate constant and the initial rate of polylysine (PL; a specific release trigger)-induced Ca2+ release (P < 0.05). However, the PL concentration dependency of the initial rate shifted towards lower concentrations of PL in HF than in N ([PL] at half maximum stimulation = 0.13 vs. 0.35 microM). The [3H]ryanodine binding assay revealed a lower Bmax (pmol/mg) in HF than in N (0.91 +/- 0.19 vs. 2.64 +/- 0.59, P < 0.05), but no difference in Kd (nM) (0.95 +/- 0.29 vs. 0.90 +/- 0.11, P = n.s.). The [PL] dependency on the enhancement of [3H]ryanodine binding again showed a shift towards lower [PL] in HF than in N. CONCLUSIONS: In pacing-induced heart failure, the Ca2+ releasing function of SR is disturbed, which may result in an intra-cellular Ca2+ transient that was slowed down.

Effects of balanced vasodilator, flosequinan, on aortic impedance in failing heart.

An arteriovenous vasodilator, flosequinan, has been shown to be effective for the treatment of acute heart failure. However, little is known as to its effect on aortic impedance, which is known to be a proper and precise expression of left ventricular (LV) afterload. To evaluate the acute cardiovascular effect of flosequinan in failing heart, we administered flosequinan intravenously to seven dogs with cardiac failure produced by an infusion of carbon powder (20-50 microm in diameter) into left main trunks of coronary artery. The LV-pump function was severely impaired after intracoronary injection of carbon powder, as evidenced by the findings that cardiac output, circumferential shortening velocity (mean Vcf), and peak +dP/dt of LV pressure were all decreased, associated with a significant increase in LV end-diastolic pressure. Flosequinan (0.9 mg/kg, i.v.) increased cardiac output by 28%, mean Vcf by 44%, and peak +dP/dt by 24%, whereas it decreased total systemic resistance by 32%, time constant of LV pressure decay by 22%, and LV end-diastolic pressure by 18%. Moreover, flosequinan substantially decreased the pulsatile components of LV afterload (i.e., characteristic impedance by 11% and arterial wave reflection coefficient by 45%). Thus flosequinan exerted not only positive inotropic but also positive lusitropic effects, in association with a significant reduction of both pulsatile and steady components of LV afterload, contributing to an improvement of LV-pump function in acute cardiac failure.

Polylysine-induced rapid Ca2+ release from cardiac sarcoplasmic reticulum.

The rapid kinetics of polylysine-induced Ca2+ release from cardiac sarcoplasmic reticulum (SR) was assessed in combination with its effect on ryanodine binding. SR vesicles were isolated from canine cardiac SR. The time course of SR Ca2+ release was continuously monitored by a stopped-flow apparatus, and [3H]ryanodine binding was done by using the filtration method. The initial rate of polylysine-induced Ca2+ release from cardiac SR revealed different concentration dependence from those observed in skeletal SR. The initial rate peaked at 0.11 microM, followed by a decrease at higher concentrations in skeletal SR, whereas it increased to 3.7 microM in cardiac SR. The [3H]ryanodine binding was also stimulated by polylysine with an identical parallelism with Ca2+ release in terms of polylysine concentration dependence. Thus we demonstrated that the cardiac SR Ca2+ release channel is sensitive to activation by polylysine and that there is a difference in the concentration dependence of polylysine-induced activation of cardiac and skeletal SR Ca2+ release channels.

TSH receptor antibody-associated thyroid dysfunction following subacute thyroiditis.

OBJECTIVE: Autoimmunity plays an important role in the development of thyrotrophin (TSH) receptor antibodies and the pathogenesis of Graves' disease and Hashimoto's thyroiditis. On the other hand, subacute thyroiditis is a self-limited inflammatory disease of presumed viral aetiology. The aim of this study was to examine whether subacute thyroiditis triggers TSH receptor antibody-associated thyroid disorders. PATIENTS: We reviewed 1,697 patients with subacute thyroiditis seen between 1985 and 1995. DESIGN AND MEASUREMENTS: We measured antibodies which inhibit the TSH binding to the TSH receptor (TBIAb), thyroid stimulating antibodies (TSAb) and antibodies that block TSH action (TBAb). Other thyroid autoantibodies were also determined. RESULTS: TBIAb became positive in 38 patients following subacute thyroiditis. Thyroid function after the development of TBIAb appeared to be influenced by the bioactivity of the antibody. Hyperthyroidism developed in the presence of TSAb, and so did hypothyroidism in the presence of TBAb, although 21 patients did not have thyroid dysfunction despite high titres of TBIAb. Fifteen out of 17 patients recovered from hyperthyroidism or hypothyroidism after the disappearance of TBIAb sometimes even without medication. TBIAb-positive patients had a high incidence of a family history of thyroid disease and positive anti-thyroid microsomal antibodies. An ophthalmopathy similar to Graves' disease was also observed in 3 patients. CONCLUSIONS: Subacute thyroiditis may trigger autoreactive B cells to produce TSH receptor antibodies, resulting in TSH receptor antibody-associated thyroid dysfunction in some patients.

Propolypeptide of von Willebrand factor is a novel ligand for very late antigen-4 integrin.

We have previously reported that propolypeptide of von Willebrand factor (pp-vWF) promotes melanoma cell adhesion in a beta1 integrin-dependent manner. In this report, we identified the alpha subunit of the cell adhesion receptor for pp-vWF as alpha4. Human leukemia cell lines that express alpha4beta1 integrin (very late antigen-4, VLA-4), but not cell lines which lack VLA-4, attached well to pp-vWF substrate and these adhesions were completely inhibited by anti-alpha4 integrin monoclonal antibody HP2/1. Adhesion of mouse melanoma expressing alpha4 integrin was also inhibited by anti-mouse alpha4 mAb PS/2. Furthermore, transfection of human alpha4 cDNA into alpha4(-) Chinese hamster ovary cells resulted in an acquisition of adhesive activity to pp-vWF, indicating that pp-vWF is a ligand for VLA-4 integrin. Using a recombinant fragment of pp-vWF, the cell attachment site was shown to be located within amino acid residues 376-455 of pp-vWF. A series of synthetic peptides covering this region were tested for the ability to promote cell attachment and a 15-residue peptide designated T2-15 (DCQDHSFSIVIETVQ, residues numbered 395-409) promoted VLA-4 dependent cell adhesion. The peptide was also capable of inhibiting cell adhesion to pp-vWF, suggesting that this sequence represents the cell attachment site. By affinity chromatography using peptide T2-15-Sepharose, it was found that alpha4beta1 integrin complex from extracts of surface iodinated B16 cells specifically bound to the peptide. These results strongly suggest that pp-vWF is a novel physiological ligand for VLA-4.

Clinical and electrophysiological characteristics of atrial standstill.

To clarify the clinical and electrophysiological characteristics of atrial standstill (AS) we studied 11 patients (7 males and 4 females), whose average age was 62 years and who were followed over a period of 4-179 months. Underlying heart disease was present in nine patients and two cases were idiopathic. Major clinical symptoms in the 11 cases included Adams-Stokes attacks, and dyspnea on exertion. In the standard 12-lead ECGs obtained on admission, the P wave was absent in six cases. Atrial flutter (AF) was noted in 3, atrial fibrillation (Af) in 1, and multifocal atrial tachycardia in 1. In some cases, the ECG initially showed AF or Af, and was transformed after several years into ectopic atrial tachycardia or an ectopic atrial rhythm with a markedly decreased amplitude of the P wave. Finally, the P wave disappeared over a prolonged period. When intracardiac mapping was performed, the atrial electrograms tended to diminish at the site of high, mid-lateral right atrium (RA). Electrograms were remained present in the vicinity of the tricuspid valve (TV) annulus. A repeated mapping and pacing study conducted in two patients revealed that the "silent" area spread toward the lower site of RA. During the average follow-up period of 64 months, four patients died. The interval until death in one patient with myocarditis was 6 months, and in another with dilated cardiomyopathy (DCM) it was 8 months. It appears that the atrial muscular lesion starts in the high lateral RA and progresses toward the lower RA, then to the vicinity of the TV annulus. A diffuse and progressive disturbance may occur not only in the atrial muscle, but also in the atrioventricular conduction system in patients with AS who had progressive myocarditis or DCM.

Pulmonary hypertension and antiphospholipid antibody in a patient with Sjögren's syndrome.

A 57-year-old female patient with Sjögren's syndrome was complicated with pulmonary hypertension (PH) and antiphospholipid antibody (aPL). She had a history of fetal losses, deep vein thrombosis and chronic thyroiditis. On admission, severe pulmonary hypertension, thrombocytopenia, lupus anticoagulant and a decreased level of protein C were found. Pulmonary artery perfusion scintigram revealed multiple defects. She died suddenly despite an intensive therapy. Intimal proliferation with angiomatoid lesions in small pulmonary arteries was observed by autopsy. Since a close relationship between PH and aPL in connective tissue disease is found, it is important to carefully analyze the antiphospholipid antibodies in patients with PH.

A case of arrhythmogenic right ventricular dysplasia with atrial flutter.

A 57-year-old male who had arrhythmogenic right ventricular dysplasia (ARVD) with recurrent atrial flutter (AF) is reported. The patient had more frequent episodes of AF than of ventricular arrhythmias. Magnetic resonance imaging, echocardiography and right ventriculography revealed dilatation of the right ventricle and endomyocardial biopsy specimens from the right ventricle showed findings which were compatible with ARVD. The left ventricular specimen, however, also revealed a loss of myocytes and interstitial fibroelastic changes. The present case demonstrates an overlap of post-inflammatory or primary endomyocardial fibroelastic changes with ARVD.

[Studies on patients with a discrepancy between free thyroid hormones and thyrotropin values].

Thyroid function has been almost exactly evaluated by the measurement of serum free thyroxine (FT4), free triiodothyronine (FT3) and thyrotropin (TSH) concentrations. However, we occasionally experience patients who show a discrepancy between free thyroid hormones and TSH values, and the assessment of thyroid function in such cases is extremely difficult. Thyroid hormone autoantibodies (THAA) interfere with radioimmunoassay (RIA) of FT4 and FT3 by giving inappropriate values. To investigate the incidence of THAA, immune precipitation of patients' sera after incubation with labelled T4 (125I-T4) or T3 (125I-T3) analog tracer was done in 394 patients with thyroid diseases. 9 patients (2.3%) showed an increased binding of 125I-T4 or 125I-T3 analog. Heterophilic antimouse antibodies in a patient's serum (human antimouse immunoglobulin antibodies: HAMA) can interfere in two-site immunometric assays (IMA) using mouse monoclonal antibodies and result in spuriously increased serum TSH concentrations. Manufacturers now customarily add nonspecific mouse immunoglobulins into their assay kits to absorb HAMA and prevent such interference. This approach may not always be enough to prevent HAMA interference in all samples. In 14 thyrotoxic patients with inappropriately high TSH measured by an IMA kit, we measured the levels of TSH by the further addition of mouse serum into this kit. Their serum TSH levels were fully suppressed except for 2 patients with a syndrome of inappropriate secretion of TSH (SITSH). The presence of abnormal albumin in the serum also interferes with RIA of FT4 and FT3. We experienced a female case of Graves' disease treated with methimazole who showed an inappropriately high serum FT3 measured by an analog tracer RIA kit, whose serum FT4, FT3 and TSH were 1.31 ng/dl, 19.3 pg/ml and 1.9 mu U/ml respectively. Although the anti-T3 autoantibody was considered to be present initially, immune precipitation of her serum with 125I-T3 analog tracer gave a negative result. In order to elucidate this finding, Sephadex-G200 chromatography of her serum after incubation with 125I-T3 analog tracer was done. Radioactivity of her serum in albumin fraction was significantly higher than that of normal control serum to indicate the presence of abnormal albumin in the serum. In conclusion, to assess the thyroid function of a patient with a discrepancy between free thyroid hormones and TSH values, it is important to consider the presence of THAA, HAMA, or rarely, an abnormal albumin.