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Recurrent intracranial germinoma with multiple spinal metastases occurred in a 16-year-old male presenting with persistent headache and visual disturbances. Computed tomography revealed enhanced lesions in the pineal region, anterior horn, and infundibulum. Conventional irradiation achieved remission, but local recurrences requiring further irradiation occurred after 23 months. Magnetic resonance imaging showed multiple spinal metastases 11 months later. Partial removal of the spinal lesions gave a histological diagnosis of typical germinoma. Postoperatively, intracranial recurrences were again detected. Chemotherapy consisting of intravenous cisplatin and etoposide achieved remission and no recurrence has occurred for 12 months.

7-Alkyl-1, 3, 6-trimethylpyrrolo[2, 3-d]pyrimidine-2, 4(1H, 3H)-diones were readily synthesized by treatment of 6-alkylamino-5-allyl-1, 3-dimethyluracils, which were derived from 5-allyl-6-chloro-1, 3-dimethyluracil and alkylamines, with bis(acetonitrile) palladium (II) chloride. In addition, 4-alkylamino-2, 5-dimethyl-2, 3-dihydrofuro[3, 2-e]pyrimidin-6-ones were easily synthesized by treatment of 5-allyl-6-chloro-1-methyluracil with alkylamines.

Silicon powder in a reaction-sintered silicon nitride crucible was heated at 1600°C in a nitrogen atomosphere. Clustered β-Si3N4 single crystals were obtained in residual silicon metal after cooling. The silicon residuals were dissolved by chemical purification using a mixture of aqueous HF and HNO3, and subsequently treated and with H2SO4. Scanning electron microscopy observation showed that large β-Si3N4 crystals without Si residuals could be successfully separated by this process.

New pyrimidine nucleoside analogs (18 compounds) were synthesized and their growth-inhibiting and differentiation-inducing activities on human myeloid leukemia HL-60 cells were examined. Some of the analogs were found to induce nitroblue tetrazolium (NBT) reducing activity in the HL-60 cells. The inducing activities of these compounds were compared at their concentrations for 50% inhibition of cell growth. TI-79 (3-benzyl-5-methyl-3-(β- d -ribofuranosyl)pyridol[2,3-d]pyrimidine-2,4(1H,3H)-dione) was a very effective inducer of NBT-reduction and of differentiation of the cells into mature granulocytes. The induction of NBT-reducing activity by TI-79 was inhibited by high concentrations of the natural nucleoside, adenosine. Other differentiation inducers, such as retinoic acid, 1α,25-dihydroxyvitamin D-3 and staurosporin markedly enhanced the induction of differentiation of HL-60 cells by TI-79. Nucleoside analogs such as TI-79 should be useful for differentiation therapy of some types of myelogenous leukemia.

The photochemical reactions of uracil and 5-fluorouracil derivatives with simple alkenes have been investigated. Photocycloaddition of uracil or 5-fluorouracil derivatives and 2, 3-dimethyl-2-butene in acetone gave an enantiomeric mixture of cross cycloadducts (4, 7) in moderate yields. Under similar conditions, diastereomers of 4-substituted 7, 7, 8, 8-tetramethyl-cis-2, 4-diazabicyclo[4.2.0]octane-3, 5-dione nucleosides (14-17) were formed from uridine or 5-fluorouridine derivatives in good yields. The structures and stereochemistry of these cycloadducts of the nucleoside series were elucidated on the basis of the proton nuclear magnetic resonance spectra and X-ray crystallographic analysis.

本研究の目的は, 歯周外科治療において歯根周囲にハイドロキシアパタイト (HAP) を填入した場合, 初期の治癒過程で歯に加わる力が歯槽骨, 歯根膜の再生にどのような影響を与えるかを解明することである。HAPを歯頸部に填入して30日目から30日間歯を移動させると, 欠損のみを作成して移動させた場合と同様に歯は大きく傾斜した。根尖部にHAPを填入た場合は, 欠損のみを作成した場合に歯の移動が小さいのに比べて大きく傾斜した。ただし, 圧迫側では直接的な骨吸収が認められる像はなかった。根尖部では骨形成量が少なく, また歯根膜を含む結合組織, HAP周囲の骨形成が圧迫側ではさらに遅延していた。歯が, 力を受けることによって, まずHAP周囲の骨の新生が遅延し, またHAP粒子問にも力が伝達されて, 結合組織の形成の遅延が生じ, それが固有歯槽骨の形成を遅延させる原因と考えられた。

[1] We examined decadal variability of the Subtropical Front (STF) of the western North Pacific by using a North Pacific ocean general circulation model (OGCM), comparing the results of three simulations with different horizontal resolutions. In the long-term mean fields, the eddy-resolving model (10 km) was able to simulate the distributions of the STF and the associated Subtropical Countercurrent (STCC) between 20°N and 30°N better than either the non-eddy-resolving model (100 km) or the eddy-permitting model (20 km) because it simulated the Kuroshio recirculation gyre more realistically. The simulated STF intensity exhibited significant decadal-scale variations: it was stronger in the late 1970s and weaker in the early 1990s. During these two periods, the simulated mode waters showed corresponding differences in their potential vorticity minima density and paths. We also investigated the relationship between the decadal-scale STF variability and atmospheric forcing. The results suggest that the decadal-scale STF variability can be largely explained by changes in the mode waters formed in the western North Pacific and advected to north of the STF by the subtropical gyre in response to a change in surface westerly winds that occurred in the mid-1970s.

Recently, various sets of protein biomarkers have been discovered in important diseases such as cancers, brain stroke, heart attack, diabetes, and so on. Many of these biomarkers are expected to be extremely valuable as targets for clinical diagnosis and drug development; however, the clinical validation is difficult and time-consuming by individual assays or due to very low concentration in an early stage of disease. For the super-sensitive and multiplex detection of target biomarkers, we have developed MUSTag (Multiple Simultaneous Tag) assay technology with innovative modification of the immuno-PCR method. In MUSTag technology, specific antibodies against several important biomarkers were linked to 100-300bp long oligonucleotides as detection tags. Each different oligo-tag simultaneously detects multiplex protein targets with extremely high sensitivity(more than 10 fg (10(-15) g)/ml) in a dose-dependent manner by qRT-PCR-based (maximum 3 plexes) or capillary electrophoretic amplification (over 30 plexes). Here we report our recent results of multiple cytokine assay or disease-specific biomarker assay using MUSTag technology, and further, clinical results from patients with cancers, ischemic brain or heart attack, who need prompt and predictive diagnosis for adequate treatment.

Intra-articular osteochondroma is a rare entity that appears as a single giant osteocartilaginous loose body in a joint cavity. The few reported cases of intra-articular osteochondroma have occurred in the knee joint. We report the case of a large osteochondral loose body in the ankle joint of a 10-year old girl and discuss the origin of the osteochondral tumor.

We recently established a technique to expand male germ line stem (GS) cells in long-term culture without losing their spermatogenic capacity. To gain insight into the genetic program of these cells, we compared the mRNA expression profile of GS cells with that of embryonic stem (ES) cells using DNA microarrays. We found 79 genes that were upregulated in GS cells compared to ES cells, including synaptonemal complex protein-1, deleted in azoospermia-like, ubiquitin-conjugating enzyme E2B, and ubiquitin carboxy-terminal hydrolase L1, all of which are functionally important for spermatogenesis. In addition, we identified a cDNA encoding the mouse ortholog of capillary morphogenesis gene (CMG)-1. CMG-1 transcripts were predominantly produced in spermatogonia and spermatocytes in mouse testis. When CMG-1 expression was attenuated in a mouse spermatocyte-derived cell line, GC-2spd(ts), by a target-specific short interfering RNA, the morphology of the cells was changed and the expression of cyclin D2 was abrogated. A reporter assay using a genomic region upstream of the mouse cyclin D2 gene revealed that this downmodulation occurs at the transcriptional level. We detected FLAG-tagged CMG-1 protein in the nuclei of transfected COS7 cells, suggesting that CMG-1 may play a unique role in the transcriptional regulation of the cyclin D2 gene. The upregulated GS genes identified in this study will provide useful information for the future investigation of spermatogonial stem cells and the early phase of male germ cell differentiation. Mol. Reprod. Dev. 955–966, 2006. © 2006 Wiley-Liss, Inc.

Aims: To assess the effects of erythropoietin(EPO) on bone metabolism in patients receivingchronic hemodialysis (HD).Methods: Forty one patients were divided intotwo groups whether they required theadministration of EPO to treat renal anemia ornot. Serial measurements of predialysis bloodsamples and bone mineral density were performedprospectively over a year.Results: The administration of EPO wasassociated with an increased serum creatinirle(11.9 ± 0.4 to 12.5 ± 0.4 mg/dl, p < 0.05),insulin-like growth factor binding protein(3.0 ± 0.2 to 3.4 ± 0.2 µg/ml, p < 0.05) as well as a decreasediron level (112 ± 7 to 88 ± 7 µg/dl, p < 0.005). Furthermore, in EPO-treated group, exogenous EPO doses correlated with the increments in1,25-dihydroxy-vitamin D (r = 0.38, p < 0.05),intact osteocalcin (r = 0.42, p < 0.05) and bonealkali-phosphatase (r = 0.53, p < 0.005), but notintact parathyroid hormone (r = 0.09). Both metacarpal index (0.47 ± 0.02 to 0.47 ± 0.02) andthe summation of gray scale/diameter (2.68 ±0.06 to 2.61 ± 0.07 mmAl), bone mineral densityparameters, remained unchanged. Conclusion: The present data provide evidencethat EPO may modulate the production of 1,25-dihydroxy-vitamin D in HD patients.Furthermore, our findings suggest that EPO therapy activates insulin-like growth factor system inHD patients, possibly through its actions on metabolism.

Pyrido [2,3-d] pyrimidine nucleosides were readily synthesized by treatment of 2',3'-O-isopropylidene-6-allylaminouridines, which were derived from 6,5'-anhydro-2',3'-O-isopropylidene-6-hydroxyuridine and allylamines with palladium(II) acetate

5-Amino-6-mercapto-1, 3-dimethyluracil (2) was prepared by the treatment of 5, 6-diamino-1, 3-dimethyluracil (1) with liquid H2S and pyridine in a sealed steel tube at 60°C for 20 h. Thiazolo[5, 4-d]pyrimidinediones 3a, b were obtained from 2 by cyclization with HCO2H and AcOH.Under stringent conditions, however, 1 was converted into the 5, 9-dihydrodipyrimido[4, 5-b : 5', 4'-e][1, 4]thiazine derivtive 4a.The structure of 4a was confirmed by spectral (nuclear magnetic resonance and mass spectra) data and by comparison with a sample which was prepared from 2 and 5-hydroxy-1, 3-dimethyluracil.Benzylation of 4a gave 1, 3, 7, 9-tetramethyl-5-benzyl (or p-bromobenzyl)-5, 9-dihydrodipyrimido[4, 5-b : 5', 4'-e][1, 4]thiazine-2, 4, 6, 8-(1H, 3H, 7H)-tetrone (4b, c) and 1, 3, 7, 9-tetramethyl-5-benzyl (or p-bromobenzyl)-5, 9-dihydropyrrolo[3, 2-d : 4, 5-d']dipyrimidine-2, 4, 6, 8-(1H, 3H, 7H)-tetrone (6a, b).

This paper introduces a time synchronization system for wired smart sensor networks to be applied to the structural health monitoring of gigantic structures. The jitter of sensor nodes in the wired network depends on the wire length between the origin and the destination of the time synchronization signals. The proposed system can theoretically achieve the accuracy to limit the jitter of sensors within 34 ns by adjusting the timing depending on the wire length, and experimentally showed the jitter of 190 m separation to be within 25 ns. The proposed system uses local area network (LAN) cables and does not require additional cabling for synchronization. Thus the proposed synchronization system can be embedded in the sensor network with minimal cost.

The results of two simple multilevel numerical experiments for the deep ocean circulation are decomposed into vertical modes, and a comparison is made between the decomposed flow fields and the results of corresponding reduced-gravity models. Although the basic equations of the multilevel model are fully nonlinear, it is a good approximation that first-mode flow fields of the multilevel model are the linear responses of a reduced-gravity model to a concentrated source and an almost uniformly distributed sink. In the multilevel model forced by a surface differential cooling the vertical advection of density anomaly in the region where the cooling is strongest acts as the major mass source for the first baroclinic mode. The convective adjustment, on the other hand, has only a minor contribution to the source for lower modes. The interior broad, uniform sink for the first mode, which is an important element in the Stommel-Arons model, is provided by the vertical diffusion of the basic density stratification. For such high modes as to constitute the stacked jets along the equator, nonlinear forcing at lower latitudes cannot be neglected.

Photosensitized cycloaddition of 2,3-dimethyl-2-butene to 2'-deoxy-uridine, thymidine and 5-fluoro-2'-deoxyuridine by the uv irradiation in acetone have been studied. From the respective reactant, a pair of diastereomers which has a cyclobutane ring were formed. However in each reaction one of the two isomers could be isolated and purified by recrystallization

Pyrido [2,3-d] pyrimidine nucleosides were readily synthesized by treatment of 2',3'-O-isopropylidene-6-allylaminouridines, which were derived from 6,5'-anhydro-2',3'-O-isopropylidene-6-hydroxyuridine and allylamines with palladium(II) acetate

1-Benzyl-6-chlorouracil (3) was prepared by benzylation of 6-chlorouracil (2) which was obtained by alkaline hydrolysis of 2,4,6-trichloropyrimidine (1)

Fifty-three patients with hemifacial spasm, six patients with trigeminal neuralgia and five patients with unilateral tinnitus were treated by a “microvascular decompression” method and follow-up results for more than one year were evaluated. Follow-up operative results of 44 patients with hemifacial spasm were : 1) excellent—24, 2) good—12, 3) fair—7 and 4) poor—1. The operative results of hemifacial spasm were evaluated according to Jannetta's classification17) combined with the degree of postoperative hearing reduction. Reduction of hearing acuity occurred in nine out of 53 patients. No recurrence of hemifacial spasm was encountered during follow-up period. It was interesting enough that the ipsilateral facial paresis which existed preoperatively gradually improved after decompressive surgery for hemifacial spasm. Eight out of 10 patients who developed facial paresis without having previous traumatizing surgical treatment and six out of 13 patients who had undergone previous peripheral surgical treatment for hemifacial spasm gradually improved after this decompressive surgery. All six patients with trigeminal neuralgia were completely cured and they noticed no sensory changes on the affected side of the face postoperatively. Four out of five patients with tinnitus were improved by the surgery. The most characteristic forms of compressing arteries were that the arteries crossdistorted the cranial nerves usually at their exit zones from the brain-stem and the arteries were angled and sclerotic focally at the compressing sites. Vertebral angiographic studies provided a key to solve the problem of why these arteries were sclerotic at the angular part and why hemifacial spasm affected one side of the face. Although the etiology of these hyperactive dysfunctions of the cranial nerves is still controversial, vascular compression-distortion seems very likely to be responsible for these syndromes. The “microvascular decompression” of cranial nerves is a refined and nontraumatic technique which seems to promise a stable and permanent cure of the hyperdysfunction of cranial nerves.

The morphological characteristics of periodontal tissue in periodontal disease have been interpreted differently by a number of clinical observers. Many have reported that the malposition and functional malocclusion of teeth is injurious to the periodontium. We reported in Part I that a system for evaluating periodontal status was developed for the diagnosis and management of the interproximal area at the initial stage of bone resorption. The patient group consisted of 36 adults, from 21 to 55 years of age. The severity score represented the calculated loss of periodontal support tissues: loss of alveolar bone, evaluated roentgenologically, bone level and pattern in vertical and horizontal form, periodontal pocket and gingival inflammation. Because poor oral hygiene and other factors caused swelling by gingival inflammation, we obtained study specimens from patients with chronic periodontal disease after a few tooth brushing instructions, and scalings during initial therapy in order to detect initial and established pathological changes in periodontal tissue. The purpose of this study was to clarify the relationship between periodontal disease status and morphological diagnostic indicators and different degrees of harmony and disharmony in the lower jaw. In all age groups the average percentage of bone loss and intraosseous defects tended to be higher in the groups categorized as Type III and Type F, and in the area that showed a very deep concave Spee curve to the occlusal plane in Pattern D. We considered that these morphological characteristics might be of secondary importance for diagnosis. Oral local factors were the primary extrinsic factor in the pathogenesis of horizontal and vertical interproximal bone absorption in the area of the premolars and molars.

The results of the microsurgical treatment of 300 patients with painful lumbar spinal diseases were reported. Radical removal of the disc material, preservation of the epidural fat tissue around the lumbar nerve roots, and meticulous hemostasis produced good results. Yet, even with this technique, a pseudoradicular or referred pain still developed after surgery, despite of the disappearance of a radicular pain or radicular signs. Pseudoradicular pain is characterized by: 1) Lasegue sign only after raising the straightened leg more than 40 degrees; 2) no radicular signs; 3) marked pains localized in the area innervated by the dorsal ramus which is involved in a pathological process; and 4) no pain in the popliteal fossa.10) Our operative results revealed that this uncomfortable pain developed most frequently after operative procedures involving facets and lateral recesses, such as in facetectomy or foraminotomy for superior facet syndrome (80% postoperatively) and for cases of lumbar herniated disc (63% postoperatively). The pain could be elicited by stimulation or irritation of the dorsal rami of the lumbar spinal nerves during surgery involving the articular facets. That was why pseudoradicular pain frequently developed after treatment of superior facet syndrome based on hypertrophied articular process or lumbar herniated discs.

The purpose of this study was to determine the oral conditions in bakery workers (473 subjects) in addition to the screening system of O'Leary and CPITN, designed for rapid recording of the level of periodontal treatment needs, and to evaluate the periodontal treatments, managed by professional cleaning (scaling) and oral hygiene instruction. The assessment of the prevalence and severity of periodontal disease and resultant treatment needs in this group showed the characteristics of chronic periodontal disease in an advanced stage in persons aged 25-29 and 50-54. 228 patients were selected for treatment for nine months and examined accurately for their periodontal condition. 137 patients continued the following group therapy three times and were reevaluated. Following the group therapy, the oral hygiene status and subjective symptoms of bleeding were improved in all groups, the effectiveness of the treatment on sextants, scoring cord three, four, showed markedly high. To achieve the treatment with few individual appointments, it is necessary to increase our knowledge of how these groups live, depending on the diversity of life style and the differences in ethnic consciousness.

A patient with an occipito-vertebral anastomosis associated with interesting clinical symptoms is presented. This 38-year-old male had a history of recurrent and reversible ischemic episodes of the vertebro-basilar system for more than 10 years. Surgical obliteration of this abnormal anastomotic channel resulted in gradual improvement of most of his clinical symptoms. The steal phenomenon of blood supply from the vertebro-basilar system to the external carotid artery via the anastomotic channel was thought to be responsible for clinical symptoms.

A 24-year-old woman suffering from left trigeminal neuralgia presented with the familial occurrence of skeletal anomalies simulating Hajdu-Cheney syndrome. She was of a short stature and had low-set ears, protrusion of the bilateral temporal and occipital bones, platybasia, basilar impression, and dental anomaly. Vertebral angiography disclosed marked displacement to the left and dorsally of the basilar artery, which was confirmed during the operation to have compressed the left trigeminal nerve in the cerebellopontine angle narrowed by the unusually protruded bony structure. Cases of Hajdu-Cheney syndrome have occasionally been reported, a few combined with facial spasm, but Hajdu-Cheney syndrome with trigeminal neuralgia is very rate. The patient's family members were surveyed. The possible cause of the neuralgia with its relation to the osteodysplasia is briefly discussed.

Pyrido[2, 3-d]pyrimidines were obtained by treatment of 6-allylaminouracils with PdCl2 at 60 °C, under which conditions the yields of the products were improved to a considerable extent as compared with our previously reported reaction. Pyrrolo[2, 3-d]pyrimidines were prepared under the above conditions from 6-(N-allyl-N-methylamino)uracils which were substituted with a methyl group at 6-NH of uracil. In addition, pyrido- and pyrrolo[2, 3-d]pyrimidine nucleosides were prepared from 6-(substituted allyl- or N-allyl-N-methylamino)uridines by adaptation of the above method. That is, the presence or absence of a substituent on the 6-amino group influences the size of ring formed. We proposed plausible pathways to explain why products having different ring sizes were formed.

近年, 骨の吸収にまで波及した歯周病変の処置として, 種々の移植材を用いた骨移植の研究が行われている。本実験の目的は, こうした一般に臨床で遭遇するような骨欠損部位に対して, 自家骨, Lyophilized dura mater「Lyodura」, Hydroxyapatite, を移植して, 組織学的に骨の新生機序を比較するところにある。そのために著者らは, 頬舌的に交通しているような進行した分岐部病変を有するビーグル犬2頭のP4, M1の欠損部を参照して, 歯周疾患に罹患していない健康なビーグル犬2頭の同部位に骨欠損モデルを形成し, 移植材の評価を試みた。その結果, 術後1週間目の所見では Lyodura も Hydroxyapatite も粗な結合組織で包囲されているが, 1ヵ月後では骨の修復はほぼ完了していた。自家骨を移植した実験部位には, 新生セメント質, 歯根膜様組織が観察されたが, Lyodura においても Hydroxyapatite においても歯根面との間には結合組織で満たされているのみであった。Lyodura も Hydroxyapatite も骨誘導能を有すると考えられるが, 歯肉の炎症が慢性的に持続している場合, その炎症反応によって骨の新生を含む歯周組織の再生が遅延していた。

Pathogenesis of hemifacial spasms is still obscure. To elucidate the etiology, 61 patients with this clinical syndrome were closely examined. Surgical findings of all patients and vertebral arteriograms of 51 patients disclosed characteristic changes of the vertebro-basilar artery system and its branches. The vertebral artery was invariably larger in diameter ipsilaterally to the affected side of the face, made a sharp or hair-pin like angulation at the origin of the third segment of the vertebral artery and gave off branches almost rectangularly from the top of this angulated part toward the internal auditory meatus. On the other hand, the S-shaped basilar artery with the abovementioned asymmetrical changes in diameter of the vertebral arteries gave off the anterior inferior cerebellar artery toward the internal auditory canal of the affected side with an absent or hypoplastic posterior inferior cerebellar artery. Operative procedures demonstrated that the facial nerve was invariably compressed by an ectated or radundant artery which showed right turn and local “arteriosclerotic” changes at its cross-compressing site. The peculiar vasculature changes of the vertebro-basilar artery and the compressing artery may be congenitally present, and subsequently, an exaggerated intraluminal blood stream or pressure of the larger sized vertebral artery is likely to apply a stronger hemodynamic force to the wall of the angulated part of the vertebral artery, resulting in ectasia or redundancy of the peripheral branches originating from this point and also wall thickening of the right-angled part of the compressing artery which just happens to lie close enough to the exit zone of the facial nerve from the brain-stem. These vasculature findings appear to provide an important key to solve the problem of why a certain artery can cross-compress the facial nerve and why the vast majority of hemifacial spasms develop on one side of the face.

Employing mitochondria of various rat tissues as enzyme sources, and pyridoxal phosphate, DPN and FMN as the coenzymes, a study was made of the distribution of three types of enzymes among the kidney, liver, heart, skeletal muscle and brain. These enzymes are transaminase, DPN-linked deaminase and FMN-linked deiodinase acting respectively upon thyroxine.The former two deaminases were found to be the most active in the kidney, and of these two the transaminase was far more active than the DPN-linked enzyme. The FMN-linked deiodinase, which appears to be a new type of enzyme of mitochondrial origin, was the most active in the liver.The specific feature of such distribution is in accord with the fact that thyroid hormones are deaminated mainly in the kidney and deiodinated in the liver in vivo.This work was supported in part by the Grant in Aid for Scientific Research-Institutional Research-from the Ministry of Education to which the authors' thanks are due.

Alternating current (50 cycles) was applied to the electrochemical model of excitation consisting of an iron core coated with the excitable membrane and immersing solution such as nitric acid or NaNO3 solution which was so prepared as to exert weak action of membrane formation, and change in the amplitude of the alternating current indicating change in impedance, and change in membrane potential were recorded to observe the stimulating action of alternating current. And the following results were obtained.1. Change in potential and impedance of the core produced by continuous flow of alternating current was similar to that observed with direct current.2. Stimulated process and change in impedance which were observed when, following the first current, the second was applied with different intervals between them, that is, the summation of stimulating action, were similar to those observed with the summation of two rectangular shocks.Discussing the above results it was concluded that the advance in the stimulated process promoted by a phase of alternating current in which it was directed towared the core would not be brought back to the initial level by the reverse phase, but would remain in some degree, and consequently that, when summated by application of many cycles, it would at last evoke excitation.

Some properties of an FMN-dependent thyroxine deiodinase were studied, employing rat liver as an enzyme source. The enzyme was present concentrated within mitochondria. Ready inactivation by boiling, inactivity under anaerobic conditions and cyanide-sensitivity were observed. Optimum pH was found between 7.0 and 7.5. Substrate specificity was rather low; T4 and TA4 were deiodinated similarly. The enzyme was inhibited by T3 probably through competition. The mitochondrial enzyme was far more prominent than any other thyroid hormone deiodinase ever reported. From the enzymatic deiodination, the chemical deiodination caused by FMN alone was distinguished. Riboflavin and FAD had a similar effect to FMN.On the basis of these facts, it was considered that the physiologically important role of the liver in deiodinating thyroid hormones should be ascribed to the FMN-dependent deiodinase of mitochondrial origin.