Topological Kagome Magnet Co3Sn2S2 Thin Flakes with High Electron Mobility and Large Anomalous Hall Effect.

Magnetic Weyl semimetals attract considerable interest not only for their topological quantum phenomena but also as an emerging materials class for realizing quantum anomalous Hall effect in the two-dimensional limit. A shandite compound Co3Sn2S2 with layered kagome-lattices is one such material, where vigorous efforts have been devoted to synthesize the two-dimensional crystal. Here, we report a synthesis of Co3Sn2S2 thin flakes with a thickness of 250 nm by chemical vapor transport method. We find that this facile bottom-up approach allows the formation of large-sized Co3Sn2S2 thin flakes of high-quality, where we identify the largest electron mobility (∼2600 cm2 V-1 s-1) among magnetic topological semimetals, as well as the large anomalous Hall conductivity (∼1400 Ω-1 cm-1) and anomalous Hall angle (∼32%) arising from the Berry curvature. Our study provides a viable platform for studying high-quality thin flakes of magnetic Weyl semimetal and stimulate further research on unexplored topological phenomena in the two-dimensional limit.

A magnetic heterostructure of topological insulators as a candidate for an axion insulator.

The axion insulator which may exhibit an exotic quantized magnetoelectric effect is one of the most interesting quantum phases predicted for the three-dimensional topological insulator (TI). The axion insulator state is expected to show up in magnetically doped TIs with magnetizations pointing inwards and outwards from the respective surfaces. Towards the realization of the axion insulator, we here engineered a TI heterostructure in which magnetic ions (Cr) are modulation-doped only in the vicinity of the top and bottom surfaces of the TI ((Bi,Sb)2Te3) film. A separation layer between the two magnetic layers weakens interlayer coupling between them, enabling the magnetization reversal of individual layers. We demonstrate the realization of the axion insulator by observing a zero Hall plateau (ZHP) (where both the Hall and longitudinal conductivity become zero) in the electric transport properties, excluding the other possible origins for the ZHP. The manifestation of the axion insulator can lead to a new stage of research on novel magnetoelectric responses in topological matter.

Five-year clinical results for treatment of intrabony defects with EMD, guided tissue regeneration and open-flap debridement: a case series.

BACKGROUND AND OBJECTIVE: Although regenerative periodontal surgery with EMD or guided tissue regeneration (GTR) has been shown to enhance periodontal regeneration, there are limited data on the long-term results following these treatment modalities. The purpose of the present study was to investigate the long-term clinical outcomes in intrabony defects following regenerative periodontal surgery with EMD or GTR compared with open-flap debridement (OFD). MATERIAL AND METHODS: Data from 40 subjects (44 teeth), with no history of smoking or systemic diseases that could interfere with periodontal disease and who received one of three surgical procedures (EMD, GTR or OFD) for two- or three-wall intrabony defects, were analyzed. Postoperative reduction in probing pocket depth, gain in clinical attachment level, gingival recession and percentage bone fill were compared at 1, 3 and 5 years. RESULTS: Reduction in probing pocket depth after GTR was significantly higher than after OFD at 1 and 3 years postoperatively, but there was no difference between the groups at 5 years. The gains in clinical attachment level for EMD (at 3 and 5 years) and for GTR (at 1, 3 and 5 years) were significantly greater than for OFD. Gingival recession after treatment with EMD and GTR showed a tendency toward positive results, whereas no such tendency was observed for OFD. Postoperative percentage bone fill for EMD and GTR was significantly greater than for OFD at 3 and 5 years. CONCLUSIONS: This is a retrospective study and an exploratory report with a high risk of bias. Within the limits of the current study, it may be concluded that superior gains in clinical attachment level and improved percentage bone fill can be obtained with EMD and GTR when compared with OFD, and these can be maintained over a period of 5 years.

IL-1ß-induced matrix metalloproteinase-3 regulates cell proliferation in rat dental pulp cells.

OBJECTIVE: We previously reported that matrix metalloproteinase-3(MMP-3) accelerates wound healing following dental pulp injury. In this study, we tested the hypothesis that induction of MMP-3 activity by interleukin-1ß would promote proliferation and apoptosis of dental pulp cells. MATERIALS AND METHODS: Dental pulp cells were isolated from rat incisors and subjected to interleukin-1ß. Matrix metalloproteinase-3 mRNA and protein expression were assessed using reverse transcription-polymerase chain reaction and Western blotting, respectively. Matrix metalloproteinase-3 activity was measured using fluorescence. Dental pulp cell proliferation and apoptosis were determined using enzyme-linked immunosorbent assays (ELISA) for BrdU and DNA fragmentation, respectively. siRNA was used to reduce MMP-3 transcripts in these cells. RESULTS: Treatment with interleukin-1ß increased MMP-3 mRNA and protein levels as well as its activity in dental pulp cells. Cell proliferation was also markedly increased, with no changes in apoptosis observed. Treatment with siRNA against MMP-3 potently suppressed this interleukin-1ß-induced increase in MMP-3 expression and activity, and also suppressed cell proliferation but unexpectedly increased apoptosis in these cells (P < 0.05). This siRNA-mediated increase in apoptosis could be reversed with exogenous MMP-3 stimulation (P < 0.05). CONCLUSIONS: Interleukin-1ß induces MMP-3-regulated cell proliferation and suppresses apoptosis in dental pulp cells.

Mouse ES cells have a potential to differentiate into odontoblast-like cells using hanging drop method.

OBJECTIVES: We examined whether mouse embryonic stem (ES) cells can differentiate into odontoblast-like cells without epithelial-mesenchymal interaction. MATERIALS AND METHODS: Cells were cultured by the 'hanging drop' method using a collagen type-I scaffold (CS) combined with bone morphogenetic protein (BMP)-4 (CS/BMP-4). Expression of odontoblast-related mRNA and protein, and cell proliferation were performed by reverse transcription-polymerase chain reaction (RT-PCR), immunofluorescence staining and WST-1 assay, respectively. RESULTS: Cells potently expressed odontoblast-related cell marker mRNAs following induction of odontoblastic differentiation. Dentin sialophosphoprotein, a marker of mature odontoblasts, was strongly expressed in differentiated ES cells. The cells also acquired an odontoblast-like functional phenotype, as evidenced by the appearance of alkaline phosphatase activity and calcification. The cell-surface expression of α2, α6, αV and αVß3 integrin proteins was rapidly upregulated in differentiated cells. Finally, anti-α2 integrin antibody suppressed the expression of odontoblastic markers in cells grown using this culture system, suggesting that α2 integrin expression in ES cells triggers their differentiation into odontoblast-like cells. CONCLUSIONS: Mouse ES cells cultured by the 'hanging drop' method are able to differentiate into cells with odontoblast-specific physiological functions and cell-surface integrin protein expression.

Cytokines induce MMP-3-regulated proliferation of embryonic stem cell-derived odontoblast-like cells.

OBJECTIVES: Matrix metalloproteinase (MMP)-3 expression increases after pulpectomy and accelerates angiogenesis in rat dental pulp by an uncharacterised mechanism. Odontoblasts, a major component of dental pulp, could represent a therapeutic target. We investigated whether MMP-3 activity is induced by cytokines and/or is associated with cell proliferation and apoptosis in embryonic stem cell-derived odontoblast-like cells. MATERIALS AND METHODS: We used reverse transcriptase polymerase chain reaction, western blotting, an MMP-3 activity assay, a BrdU-cell proliferation enzyme-linked immunosorbent assay and DNA fragmentation analysis to evaluate siRNA-mediated downregulation of MMP-3 expression and activity, and any changes in the proliferative and apoptotic responses associated with this reduced expression. RESULTS: Pro-inflammatory cytokines (interleukin-1ß, tumour necrosis factor-α and interferon-γ, at relatively low concentrations) induced MMP-3 mRNA and protein expression, and increased MMP-3 activity and cell proliferation, but not apoptosis. MMP-3 silencing produced a potent and significant suppression of cytokine-induced MMP-3 expression and activity, decreased cell proliferation and increased apoptosis. These effects were rescued by application of exogenous MMP-3. CONCLUSIONS: Our results suggest that pro-inflammatory cytokines induce MMP-3-regulated cell proliferation and anti-apoptosis effects in odontoblast-like cells derived from embryonic stem cells, in addition to their well-documented destructive role in inflammation.

Method and equipment for estimation activity nuclides in samples of finite dimensions.

This study presents a method of measuring the activity of a specific radionuclide 234mPa in samples placed in bulk transport containers under changing background conditions. The method makes it possible to measure specific activity of 234 mPa in objects without the need for sampling. The change in the effective sample volume limited by the surfaces of the containers is considered depending on the density of the measured material and the energy of gamma radiation of the radionuclide. The high sensitivity of scintillation detector, supplemented by adequate Monte Carlo simulation, allows spectrum measurements to be taken in a short time (less than an hour) with subsequent determination of specific activity. A comparison of measurement results and calculation of 234mPa activity in samples with different densities and compositions using the proposed algorithm, and those obtained by an HPGe spectrometer, demonstrated the high efficiency of the proposed solution.

Reduced angiotensin II levels in the cerebrospinal fluid of patients with amyotrophic lateral sclerosis.

BACKGROUND: Recent studies suggest that angiotensin II, a major substrate in the renin-angiotensin system, protects neurons through stimulation of its type 2 receptors. However, quite a few clinical studies of angiotensin II levels have shown their relation to disease severity in neurodegenerative disorders, including amyotrophic lateral sclerosis (ALS). AIMS OF THE STUDY: To clarify the significance of angiotensin II in ALS. METHODS: We assayed angiotensin II concentrations in cerebrospinal fluid (CSF) samples from 23 patients with ALS, nine patients with spinocerebellar degeneration (SCD) and 24 control individuals. We evaluated the disability levels of patients with ALS using the Revised ALS Functional Rating Scale (ALSFRS-R) and calculated the disease progression rate (DPR). RESULTS: CSF angiotensin II levels were significantly lower in the ALS group compared with that in the control group (P = 0.00864), and showed a significant positive correlation with scores on the ALSFRS-R, and a significant negative correlation with the DPR. CONCLUSIONS: In the present study, we reveal for the first time that angiotensin II levels in the CSF from patients with ALS are significantly reduced and significantly associated with disease severity and progression rate. These findings suggest that reduced levels of intrathecal angiotensin II may play a role in ALS.

Animal Models of Vasculitis.

The diagnosis of vasculitis in rheumatoid arthritis (RV) is associated with considerable mortality; therefore, understanding the basic mechanisms underlying the pathogenesis of vasculitis is very important. Animal models of vasculitis have contributed to elucidating such mechanisms. We here introduce a Candida albicans water-soluble (CAWS) glycoprotein-induced vasculitis model and the methodological approach to evaluate inflammatory vascular change.

The Climate Range Expansion of Aedes albopictus (Diptera: Culicidae) in Asia Inferred From the Distribution of Albopictus Subgroup Species of Aedes (Stegomyia).

We compared climatic distribution ranges between Aedes albopictus (Skuse) (Diptera: Culicidae) and the five wild (nondomesticated) species of Albopictus Subgroup of Scutellaris Group of Aedes (Stegomyia) in southern Asia. Distribution sites of the wild species concentrate in seasonal forest and savannah climate zones in India, Indochina, and southern China. The distribution of Ae. albopictus is broader than the wild species under 1) tropical rain-forest climate, 2) steppe and temperate savannah climate, and 3) continental climate with large seasonal temperature variation (hot summer and cold winter) at temperate lowlands (northernmost sites 40°N in Ae. albopictus vs 32°N in the wild species). However, the distribution of Ae. albopictus is more limited at tropical and subtropical highlands where the climate is cool but less continental (small seasonal variation, mild summer, and winter). We discuss a possibility that the broader climate ranges of Ae. albopictus are ecological or eco-evolutionary consequences of adaptation to human habitats. We also propose a general scenario for the origin, dispersal, and adaptation of Ae. albopictus in Asia as a hypothesis for future research.

Quantized chiral edge conduction on domain walls of a magnetic topological insulator.

Electronic ordering in magnetic and dielectric materials forms domains with different signs of order parameters. The control of configuration and motion of the domain walls (DWs) enables nonvolatile responses against minute external fields. Here, we realize chiral edge states (CESs) on the magnetic DWs of a magnetic topological insulator. We design and fabricate the magnetic domains in the quantum anomalous Hall state with the tip of a magnetic force microscope and prove the existence of the chiral one-dimensional edge conduction along the prescribed DWs through transport measurements. The proof-of-concept devices based on reconfigurable CESs and Landauer-Büttiker formalism are realized for multiple-domain configurations with well-defined DW channels. Our results may lead to the realization of low-power-consumption spintronic devices.

Increase in RANKL: OPG ratio in synovia of patients with temporomandibular joint disorder.

Although a recent study suggested the involvement of RANKL and osteoprotegerin (OPG) in the pathogenesis of bone-destructive disease, no study has focused on the RANKL:OPG ratio in the synovial fluid of patients with temporomandibular joint (TMJ) disorder. This communication reports on the concentrations of RANKL and OPG in synovial fluid from TMJ patients and healthy control individuals. In contrast to an unchanged concentration of RANKL, a strong decrease in the concentration of OPG was detected in the synovial fluid from patients with TMJ internal derangement. Treatment with the synovial fluid of osteoarthritis (OA) patients resulted in the high production of osteoclast-like cells from blood mononuclear cells in vitro, as well as in pit formation in dentin slices. The addition of anti-RANKL IgG or OPG attenuated OA-synovial fluid-induced osteoclast formation, suggesting that the increase in the RANKL:OPG ratio in the microenvironment of the joint has the potential to induce osteoclastogenesis in TMJ osteoarthritis.

Depth of side-chain pocket in the S2 subsite of dipeptidyl peptidase IV.

Kinetic studies of pig kidney dipeptidyl peptidase IV (dipeptidyl-peptide hydrolase, EC 3.4.14.5) were carried out using substrates possessing a side-chain of different length at the P2 position (or amino-terminal position in this case) such as Lys-, Arg-, Phe-, Met-, Ser-, His-, Glu- and Gly-Pro-pNA. The hydrolytic coefficient (Kcat/Km) has determined in the order Met- greater than Glu- greater than Ser- greater than His- greater than Phe- greater than Lys- greater than Gly- greater than Arg-, indicating a gradual increase with elongation of the side-chain from 0.03 to 0.60 nm followed by a decline when side-chain length approached 0.70 nm. Thus, the most probable depth of the side-chain pocket at the S2 subsite of the enzyme is proposed to be 0.50-0.60nm.

Coexpression of GTP cyclohydrolase I and inducible nitric oxide synthase mRNAs in mouse osteoblastic cells activated by proinflammatory cytokines.

Proinflammatory cytokines, a combination of IL-1beta, TNF-alpha, and IFN-gamma, caused mRNA expression of GTP cyclohydrolase I (GTP-CH), the rate-limiting enzyme in tetrahydrobiopterin (BH4) biosynthesis, and of inducible nitric oxide synthase (iNOS) in a well-characterized osteoblastic clone MC3T3-E1 cell line. We found the expression of the GTP-CH gene in osteoblasts for the first time. The expression of GTP-CH and iNOS mRNAs was found to be maximal at 3 and 9 h, respectively. The expression of both genes elicited increases in BH4 and NO levels. Pharmacological studies using 2,4-diamino-6-hydroxypyrimidine, an inhibitor of GTP-CH activity, showed that BH4 is involved in the activity of iNOS, but not in the induction of iNOS mRNA. The results using an inhibitor of nuclear factor (NF)-kappaB and activating protein-1 (AP-1) activation suggested that coinduction of the two genes in response to cytokines occurred via activation of NF-kappaB and AP-1. In MC3T3-E1 cells BH4 and sepiapterin, producing BH4, could protect against apoptosis, i.e. the degradation of nuclear DNA in the cells, induced by NO derived from S-nitroso-N-acetyl-D-L-penicillamine. These results suggest that the induction of BH4 together with NO by proinflammatory cytokines could protect against NO-induced apoptosis in MC3T3-E1 cells.

Dual roles for NF-kappaB activation in osteoblastic cells by serum deprivation: osteoblastic apoptosis and cell-cycle arrest.

To clarify the mechanisms of osteoblastic cell death, we examined whether serum deprivation would cause activation of the apoptotic signal cascade and arrest of the cell cycle in mouse osteoblastic MC3T3-E1 cells. Serum withdrawal from osteoblastic cell cultures resulted in growth arrest and cell-cycle arrest at G0/G1, which actions were accompanied by transient and potent activation of NF-kappaB, caspase-8, caspase-2, caspase-3, and caspase-9 in this order. Apoptosis, but not necrosis, in serum-deprived cells could be detected by FACS using Annexin-V/propidium iodine double staining. Serum deprivation also resulted in transient activation of the 20S proteasome, which is an important component for regulation of the cell cycle by the ubiquitin-proteasome system. The 20S proteasome inhibitor (PSI) but not NF-kappaB inhibitor SN50 suppressed the activation of proteasomes in serum-deprived cells. Although caspase inhibitors could not prevent the G0/G1 arrest in the serum-deprived cells, SN50 and the 20S proteasome inhibitor could block it. Since SN50, 20S proteasome inhibitor and caspase inhibitor could rescue cells from serum deprivation-induced apoptosis, the pathway for NF-kappaB/caspase activation is independent of the NF-kappaB/cell-cycle pathway, and the events downstream of the NF-kappaB/caspase-9 cascade lead to apoptosis. Taken together, our present results identify a novel role for NF-kappaB in cell-cycle and apoptosis regulation and underscore the significance of each independent signal cascade in serum-deprived osteoblastic cells.

A quantitative analysis of cell surface glycosphingolipid with a fluorescence activated cell sorter.

The fluorescence activated cell sorter (FACS) was used with an indirect membrane immunofluorescence technique to detect antibody against the Forssman antigen, a glycosphingolipid. Sheep erythrocytes, which contain Forssman antigen as a major membrane glycosphingolipid, were used as the target antigen. Detection of the anti-Forssman antibody on the sheep erythrocytes was done with specific fluorescein-conjugated second antibody and analyzed on a FACS. Compared to other available methods, analysis with the FACS was simple, sensitive, reproducible and quantitative. More than 250 pg of antibody could be detected. In addition, as little as 1 ng of Forssman antigen could be estimated by a binding inhibition experiment.

Signal transduction system for interleukin-6 and interleukin-11 synthesis stimulated by epinephrine in human osteoblasts and human osteogenic sarcoma cells.

Epinephrine increased gene- and protein-expression of interleukin-6 (IL-6) and interleukin-11 (IL-11), which are capable of stimulating the development of osteoclasts from their hematopoietic precursors, in human osteoblast (SaM-1) and human osteosarcoma (SaOS-2, HOS, and MG-63) cell lines. An increase in IL-6 and IL-11 synthesis in response to epinephrine appeared to be a common feature in osteoblastic cells, but the magnitude of expression was different in these cell lines. In HOS cells treated with epinephrine, increases of IL-6 and IL-11 synthesis were inhibited by timolol (a beta-blocker), H-89 (N-[2-((p-bromocinnamyl)amino)ethyl]-5-isoquinolinesulfonamide; an inhibitor of protein kinase A (PKA)) and SB203580 [4-(4-fluorophenyl)-2-(4-methylsulfinylphenyl)-5-(4-pyridyl)1H-imidazole; an inhibitor of p38 mitogen-activated protein kinase (MAPK)], but not by phentolamine (an alpha-blocker), calphostin C [an inhibitor of protein kinase C (PKC)], or PD98059 (2'-amino-3'-methoxyflavone; an inhibitor of classic MAPK), suggesting a common pathway mediated by beta-adrenergic receptors in the PKA and p38 systems involved in the signal transduction of IL-6 and IL-11. Furthermore, expression of both genes was inhibited by curcumin [an inhibitor of activating protein-1 (AP-1) activation], but not by pyrrolidine dithiocarbamate (PDTC) [an inhibitor of nuclear factor (NF)-kappaB]. The pharmacological study suggested that coinduction of the two genes in response to epinephrine occurred via activation of AP-1. The findings of the present study suggest that coinduction of IL-6 and IL-11 in response to epinephrine probably occurs via the PKA and p38 MAPK systems, leading to the transcriptional activation of AP-1 in human osteoblastic cells.

Involvement of nitric oxide and biopterin in proinflammatory cytokine-induced apoptotic cell death in mouse osteoblastic cell line MC3T3-E1.

We previously demonstrated that the addition of proinflammatory cytokines (tumor necrosis factor-alpha, interleukin-1beta, and interferon-gamma) caused induction of mRNAs for inducible nitric oxide (NO) synthase and GTP cyclohydrolase I, a rate-limiting enzyme for 5,6,7,8-tetrahydrobiopterin (BH4) biosynthesis, and produced their end-products, NO and BH4, in osteoblastic cells. In the present study, we examined whether NO and BH4, biologically active substances produced in response to proinflammatory cytokines, are involved in the effect of these cytokines on cell viability and apoptotic cell death involving DNA fragmentation. Cytokines as well as S-nitroso-N-acetyl-d,l-penicillamine, an NO generator, decreased cell viability, whereas sepiapterin, which was converted intracellularly to BH4, increased it. The examination of cytotoxicity measured in terms of lactate dehydrogenase release and apoptotic cell death assessed by flow cytometric analysis showed that cytokine-induced reduction of cell viability may be based upon cell death by apoptosis, but not lytic death as in necrosis. In the presence of sepiapterin, cytokine treatment resulted in a statistically pronounced reduction in the amount of DNA fragmentation. Furthermore, this fragmentation could be blocked by 2-(4-carboxy-phenyl)-4,4,5,5-tetramethylimidazole-1-oxyl 3-oxide, an NO scavenger. These results suggest that cytokine-induced apoptotic cell death is attributed to NO and is protected by BH4, and that osteoblastic cells in response to proinflammatory cytokines operate both a stimulatory process resulting in NO production and an inhibitory one resulting in BH4 production for apoptotic cell death. Cytokine-induced apoptotic cell death may be a consequence of the predominance of the stimulatory process over the inhibitory process.

Differential reactivities of fucosyl GM1 and GM1 gangliosides on rat erythrocyte membrane revealed by analysis with anti-fucosyl GM1 and GM1 antisera.

Rat erythrocytes contained ganglio-series gangliosides, GM1, fucosyl GM1, and GD1a, in a high concentration. The concentrations of GM1, fucosyl GM1, and GD1a in rat erythrocyte ghosts were 889.0 nmol, 470.6 nmol, and 462.0 nmol per g dry weight, respectively, and the molar ratio of lipid-bound sialic acid, cholesterol and lipid-bound phosphorus was 3.1:73.9:100.0. The reactions of fucosyl GM1 and GM1 on rat erythrocytes with rabbit anti-fucosyl GM1 and anti-GM1 antisera were measured by means of haemolysis in the presence of complement and a binding assay of antibodies with a FACS after staining erythrocytes by the indirect membrane immunofluorescence technique. When measured by ELISA, anti-fucosyl GM1 antiserum was found to react almost exclusively with fucosyl GM1 with a slight cross-reaction with GM1, but anti-GM1 antiserum cross-reacted to a significant extent with asialo GM1. Rat erythrocytes were haemolyzed specifically with anti-fucosyl GM1 antiserum, but not with antisera to GM1, asialo GM1, asialo GM2, Forssman and globoside, and the haemolysis was proved to be definitely caused by the specific recognition of fucosyl GM1 on rat erythrocytes by anti-fucosyl GM1 antibody according to the haemolysis inhibition reaction using various glycosphingolipid-containing liposomes as inhibitors. In addition, although the binding of anti-fucosyl GM1 antibody on rat erythrocytes was clearly demonstrated with a FACS, anti-GM1 antibody did not bind. The observations that the haemolysis of rat erythrocytes and the binding of antibody to rat erythrocytes were found only with anti-fucosyl GM1 antiserum, and not with anti-GM1 antiserum, but that nevertheless the titer of anti-GM1 antiserum was higher than that of anti-fucosyl GM1 antiserum and GM1 on rat erythrocytes was more abundant in concentration than fucosyl GM1, seem to be a matter of great importance in assessing the specificity of anti-ganglioside antibody and the surface distribution of gangliosides on the cell.

Purification and immunochemical properties of tyrosine hydroxylase in human brain.

Tyrosine hydroxylase (TH) was isolated from human brain (caudate nucleus + putamen). The major form of the active enzyme in the cytoplasmic fraction was purified to apparent homogeneity. The molecular weight of the purified enzyme was estimated to be 280 kdalton by gel filtration. Sodium dodecyl sulfate gel electrophoresis (SDS-PAGE) of the purified enzyme gave a single subunit with mol. wt 60 kdalton, which is similar to the subunit of human adrenal TH. Using a sandwich enzyme immunoassay (EIA), the presence of inactive form(s) of TH in human brain was demonstrated, and the total content of this immunoinactive form(s) was approx. 8 times higher than that of the active form. By the Western blot technique after two-dimensional (2-D) electrophoresis, TH in the crude fraction of the human brain was found to consist of multiple forms with different pI-values and with the same molecular weight. The pl of the major spots ranged from 5.3 to 5.8, and that of the minor spot was 6.0. Because the pl of the purified enzyme preparation was 6.0, this protein with pI at 6.0 may be the active form of TH.