Primary mutagenicity screening of food additives currently used in Japan

Salmonella/microsome tests (Ames tests) and chromosomal aberration tests in vitro using a Chinese hamster fibroblast cell line were carried out on 190 synthetic food additives and 52 food additives derived from natural sources, all of which are currently used in Japan. Fourteen out of 200 tested in the Ames assay showed positive effects and 54 out of 242 were positive in the chromosome test. Three additives (erythorbic acid, chlorine dioxide and beet red) were positive only in the Ames test, although their mutagenic potentials were relatively weak, while 43 additives were positive only in the chromosome test. Eleven additives (calcium hypochlorite, cinnamic aldehyde, L-cysteine monohydrochloride, Food Green No. 3 (Fast Green FCF), hydrogen peroxide, potassium bromate, sodium chlorite, sodium hypochlorite, sodium nitrite, cacao pigment and caramel) were positive in both the Ames test and the chromosome test. The usefulness of such primary screening tests combining two different genetic end-points, gene mutation and chromosomal aberration, and some correlation between mutagenicity and carcinogenicity of food additives are discussed.

Production of tumor necrosis factor-alpha by microglia and astrocytes in culture

Stimulation of mouse astrocytes and microglia in enriched culture by lipopolysaccharide (LPS) results in the production of a cytotoxic factor that is functionally similar to macrophage-derived tumor necrosis factor-alpha (TNF). This cytotoxic factor kills murine L929 cells, and is neutralized by a monoclonal anti-mouse TNF. The production of this factor is inhibited by pretreatment of cells by actinomycin D. Microglia are more sensitive to LPS and produce much higher activity of cytotoxicity in lower concentration of LPS than astrocytes. These results suggest that microglia are the major producers of TNF in the brain and may play a role in certain pathological conditions in the brain.

Complete sequence and gene organization of the genome of a hyper-thermophilic archaebacterium, Pyrococcus horikoshii OT3

The complete sequence of the genome of a hyper-thermophilic archaebacterium, Pyrococcus horikoshii OT3, has been determined by assembling the sequences of the physical map-based contigs of fosmid clones and of long polymerase chain reaction (PCR) products which were used for gap-filling. The entire length of the genome was 1,738,505 bp. The authenticity of the entire genome sequence was supported by restriction analysis of long PCR products, which were directly amplified from the genomic DNA. As the potential protein-coding regions, a total of 2061 open reading frames (ORFs) were assigned, and by similarity search against public databases, 406 (19.7%) were related to genes with putative function and 453 (22.0%) to the sequences registered but with unknown function. The remaining 1202 ORFs (58.3%) did not show any significant similarity to the sequences in the databases. Sequence comparison among the assigned ORFs in the genome provided evidence that a considerable number of ORFs were generated by sequence duplication. By similarity search, 11 ORFs were assumed to contain the intein elements. The RNA genes identified were a single 16S-23S rRNA operon, two 5S rRNA genes and 46 tRNA genes including two with the intron structure. All the assigned ORFs and RNA coding regions occupied 91.25% of the whole genome. The data presented in this paper are available on the internet at http:@www.nite.go.jp.

Inflammatory Process in Parkinsons Disease: Role for Cytokines

Parkinson's disease (PD) is a movement disorder caused by degeneration of the nigrostriatal dopamine (DA) neurons in the substantia nigra pars compacta and the resultant deficiency in the neurotransmitter DA at the nerve terminals in the striatum. We and other investigators found increased levels of pro-inflammatory cytokines such as tumor necrosis factor (TNF)-alpha, interleukin (IL)-1beta, and IL-6, and decreased levels of neurotrophins such as brain-derived neurotrophic factor (BDNF) in the nigrostriatal region of postmortem brains and/or in the ventricular or lumbar cerebrospinal fluid (CSF) from patients with sporadic PD, and in animal models, such as 1-methyl-4-phenyl-1, 2, 3, 6-tetrahydropyridine (MPTP)- and 6-hydroxydopamine (6-OHDA)-induced PD. These changes in cytokine and neurotrophin levels may be initiated by activated microglia, which may then promote apoptotic cell death and subsequent phagocytosis of DA neurons. Cytokines as pleiotropic factors, promote signals that either lead to cell death or exert neuroprotective effects. The discovery of toxic changes in trophic microglia by M. Sawada and co-workers is important to this point. Ultimately, microglial cells may regulate cellular changes that cause either harm or benefit by producing cytokines or neurotrophins depending upon the primary cause and the circumstances during the inflammatory process of PD.

Arytenoid adduction for unilateral vocal cord paralysis

The arytenoid adduction technique was devised and performed under local anesthesia on five patients with unilateral vocal cord paralysis. It is especially indicated for the case of a wide, glottal chink and a difference in the level of the two cords. The muscle process is pulled by two 3-0 nylon sutures in simulation of the functions of the lateral cricoarytenoid muscle and the lateral thyroarytenoid muscle. Improvement of voice after surgery was dramatic in all of the patients who were operated on. The surgical procedure is rather simple, easy, and allows adjustment of the degree of arytenoid adduction during surgery to produce the best voice obtainable.

Changes in superoxide radical and lipid peroxide formation in the brain, heart and liver during the lifetime of the rat

The free radical theory of aging was examined by measuring the formation of superoxide radical (SOR) and the level of lipid peroxides in various tissues of the aging rat. A significant increase in SOR production was seen in mitochondria prepared from the brain and the heart as rats aged. An elevation in the level of lipid peroxidation was also found in whole tissue homogenates of the brain and the liver. Vitamin E concentrations in the blood rose rapidly in young rats and remained steady except for a non significant drop in old animals. These results suggest that age-related degeneration of various tissues in the rat may be due to a rise in free radical production in the mitochondria.

Role of cytokines in inflammatory process in Parkinson's disease

We investigated whether the cytokines produced in activated microglia in the substantia nigra (SN) and putamen in sporadic Parkinson's disease (PD) are neuroprotective or neurotoxic. In autopsy brains of PD, the number of MHC class II (CR3/43)-positive activated microglia, which were also ICAM-1 (CD 54)-, LFA-1 (CD 11a)-, TNF-alpha-, and IL-6-positive, increased in the SN and putamen during progress of PD. At the early stage activated microglia were mainly associated with tyrosine hydroxylase (TH)-positive neurites in the putamen, and at the advanced stage with damaged TH-positive neurons in the SN. The activated microglia in PD were observed not only in the nigro-striatal region, but also in various brain regions such as the hippocampus and cerebral cortex. We examined the distribution of activated microglia and the expression of cytokines and neurotrophins in the hippocampus of PD and Lewy body disease (LBD). The levels of IL-6 and TNF-alpha mRNAs increased both in PD and LBD, but those of BDNF mRNA and protein drastically decreased specifically in LBD, in which neuronal loss was observed not only in the nigro-striatum but also in the hippocampus. The results suggest activated microglia in the hippocampus to be probably neuroprotective in PD, but those to be neurotoxic in LBD. As an evidence supporting this hypothesis, two subsets of microglia were isolated from mouse brain by cell sorting: one subset with high production of reactive oxygen species (ROS) and the other with no production of ROS. When co-cultured with neuronal cells, one microglia clone with high ROS production was neurotoxic, but another clone with no ROS production neuroprotective. On the other hand, Sawada with coworkers found that a neuroprotective microglial clone in a culture experiment converted to a toxic microglial clone by transduction of the HIV-1 Nef protein with increasing NADPH oxidase activity. Taken together, all these results suggest that activated microglia may change in vivo from neuroprotective to neurotoxic subtsets as degeneration of dopamine neurons in the SN progresses in PD. We conclude that the cytokines from activated microglia in the SN and putamen may be initially neuroprotective, but may later become neurotoxic during the progress of PD. Toxic change of activated microglia may also occur in Alzheimer's disease and other neurodegenerative diseases in which inflammatory process is found.

Possible role of tumor necrosis factor and interleukin-1 in the development of diabetic nephropathy

The possibility that tumor necrosis factor (TNF) and interleukin-1 (IL-1) could participate in the development of diabetic nephropathy was evaluated in streptozocin (STZ)-treated diabetic rats. Diabetic rats were divided into two groups: aminoguanidine treated group (25 mg/kg body wt, daily i.p. injection; DM-AG group) and untreated group (DM group). Non-diabetic age-matched rats were also divided into two groups with the same manner and used as controls. After twelve weeks of treatment, glomerular basement membranes (GBM) were isolated from rats of each experimental group. When thioglycollate-elicited peritoneal macrophages (M phi) from normal rats were incubated with these GBM materials, GBM from DM group induced significantly greater levels of TNF and IL-1 production than did GBM from other three groups with at doses of 2.5 to 10 mg. The TNF and IL-1 production by stimulation of GBM from the DM-AG group were similar to those from each control group. Aminoguanidine treatment significantly decreased the accumulation of advanced glycation end-products (AGEs) in GBM of diabetic rats. These findings suggest that AGE-proteins may be involved in the production of TNF and IL-1 from M phi. AGE-induced cytokines may be implicated in the development of diabetic nephropathy.

Effects of colony stimulating factors on isolated microglia in vitro

Effects of colony stimulating factors (CSF), known regulators for cells in monocytic lineage, on isolated microglia were examined. Interleukin-3 (IL-3) induced only morphological changes in rod-shaped microglia, while granulocyte-macrophage CSF (GM-CSF) and CSF-1 induced both morphological changes and proliferation of microglia. CSF-1 also activated the enzyme activity of microglia. These observations indicated that, in terms of regulation by cytokines, microglia are similar to mature cells in monocytic lineage. Although astrocytes reportedly produce IL-3 and GM-CSF, the effects of astrocyte-conditioned medium (Ast-Sup) were different from those of either IL-3 or GM-CSF. Ast-Sup caused ameboid microglia to become ramified, and did not induce proliferation of microglia. Factors from astrocytes may have a role in the transformation of microglia which occurs in either normal developing brain or inflammation in the brain.

Interleukin-10 inhibits both production of cytokines and expression of cytokine receptors in microglia

Microglia, macrophage-like cells in the CNS, are multifunctional cells; they play an important role in removal of dead cells or their remnants by phagocytosis in the CNS degeneration and are one of important cells in the CNS cytokine network to produce and respond to a variety of cytokines. The functions of microglia are regulated by inhibitory cytokines. We have reported the expression of interleukin (IL)-10, one of the inhibitory cytokines, and its receptor in mouse microglia; therefore, IL-10 may affect microglial functions. In this study, we investigated the effects of IL-10 on purified microglia in culture. IL-10 inhibited lipopolysaccharide-induced IL-1beta and tumor necrosis factor-alpha production, lysosomal enzyme activity, and superoxide anion production in a dose-dependent manner, but did not affect granulocyte/ macrophage colony-stimulating factor-dependent proliferation of microglia. IL-10 also decreased the expression of both IL-6 receptor and lipopolysaccharide-induced IL-2 receptor but not IL-4 receptor on microglia as measured by flow cytometric analysis with an indirect immunofluorescence technique. IL-10 also decreased mRNA expression of IL-2 and IL-6 cytokine receptors. These results suggest that IL-10 is a unique and potent inhibitory factor in the CNS cytokine network involved in decreasing the expression of cytokine receptors as well as cytokine production by microglia.

Activation and proliferation of the isolated microglia by colony stimulating factor-1 and possible involvement of protein kinase C

Microglia were isolated from primary mixed brain cell culture of normal newborn mice and then cultivated. They were able to be maintained in vitro for 1-2 months, but incorporated little [3H]thymidine under normal culture conditions. When treated with the conditioned medium of L929 mouse fibroblast cells as a crude CSF-1 (mouse macrophage-colony stimulating factor) or purified CSF-1, microglia showed morphological changes and increased in both cell number and [3H]thymidine uptake. In addition, crude CSF-1 increased lysosomal enzyme activity and superoxide anion formation of microglia up to 2 and 3.8 fold as control value, respectively. These effects of CSF-1 were not observed in the purified astrocyte culture. Purified microglia had CSF-1 receptors which were recognized by the anti-CSF-1 receptor antibody that arose from a peptide of a product of proto-oncogene, c-fms. 12-O-Tetradecanoylphorbol-13-acetate (TPA) also increased microglia cell number and their biochemical activities, suggesting the possible involvement of protein kinase C activation. Protein kinase inhibitors, such as staurosporine or H-7, inhibited the effects of both CSF-1 and TPA. These results indicate that microglia may be regulated in its biochemical and proliferation activities by CSF-1 and that this may occur via activation of protein kinase C.

In vivo setting behaviour of fast-setting calcium phosphate cement

The in vivo setting behaviour of fast-setting calcium phosphate cement (FSCPC) between femoral muscles of the rat was investigated to evaluate the possible value of FSCPC for medical and dental application. Conventional CPC (c-CPC) and FSCPC were implanted between femoral muscles, and various aspects of the setting behaviour such as setting time, mechanical strength and conversion ratio of cement into hydroxyapatite (HAP: Ca10(PO4)6(OH)2) were measured by the Vicat needle method, diametral tensile strength (DTS) measurement, and quantitative powder X-ray diffraction (XRD) analysis, respectively. The setting time of FSCPC in vivo was 5-7 min, in contrast to 48 min for c-CPC. As a result of its fast setting, set specimens of FSCPC showed higher mechanical strength from the initial stage than c-CPC. Higher DTS values were observed in FSCPC than c-CPC implanted after 24 h. Powder XRD analysis revealed faster conversion of FSCPC than c-CPC into HAP, which was responsible both for the faster setting and higher mechanical strength from the initial stage. We concluded, therefore, that FSCPC may be used for a wide range of clinical applications, i.e. fields where fast setting is required such as orthopaedic, plastic and reconstructive, and oral and maxillofacial surgery.

Molecular cloning and characterization of a plasma membrane-associated sialidase specific for gangliosides

Gangliosides are plasma membrane components thought to play important roles in cell surface interactions, cell differentiation, and transmembrane signaling. A mammalian sialidase located in plasma membranes is unique in specifically hydrolyzing gangliosides, suggesting crucial roles in regulation of cell surface functions. Here we describe the cloning and expression of a cDNA for the ganglioside sialidase, isolated from a bovine brain cDNA library based on the amino acid sequence of the purified enzyme from bovine brain. This cDNA encodes a 428-amino acid protein containing a putative transmembrane domain and the three Asp boxes characteristic of sialidases and sharing 19-38% sequence identity with other sialidases. Northern blot and polymerase chain reaction analyses revealed a general distribution of the gene in mammalian species, including man, and the mouse. In COS-7 cells transiently expressing the sialidase, the activity was found to be 40-fold that of the control level with ganglioside substrates in the presence of Triton X-100, and the hydrolysis was almost specific to gangliosides other than GM1 and GM2, both alpha2-->3 and alpha2-->8 sialyl linkages being susceptible. The major subcellular localization of the expressed sialidase was assessed to be plasma membrane by Percoll density gradient centrifugation of cell homogenates and by immunofluorescence staining of the transfected COS-7 cells. Analysis of the membrane topology by protease protection assay suggested that this sialidase has a type I membrane orientation with its amino terminus facing to the extracytoplasmic side and lacking a signal sequence.

Induction of in vitro tumor cell invasion of cellular monolayers by lysophosphatidic acid or phospholipase D

Serum is known to be required for invasion or phagokinesis of certain tumor cells, although the mechanism of its action is not well understood yet. In the in vitro invasion assay system we have developed, MM1 cells exhibiting extensive invasiveness against cultured mesothelial cell monolayers in the presence of 10% fetal calf serum did not invade them without serum. Human small cell lung cancer (OC10) cells also required serum in invasion. Serum could be completely substituted by oleoyl-lysophosphatidic acid (LPA) or bacterial phospholipase D (PLD). Phosphatidic acid also had an invasion-inducing activity, though to a lesser degree. Since human ovarian cancer (RMUG-S) cells require neither serum, LPA nor the PLD for invasion of mesothelial cell monolayers, the production of phospholipid like LPA, a candidate for intracellular second messenger, in tumor cells seems critical for the invasion by MM1 cells or OC10 cells. This result suggests a possible participation of particular signaling cascade, PLD-LPA(PA) system, in the invasion of certain tumor cells.

TNF alpha induces IL-6 production by astrocytes but not by microglia

Astrocytes and microglia, both produced interleukin-6 (IL-6) in culture by lipopolysaccharide (LPS) stimulation. IL-6 activity was detected 3-5 h after LPS stimulation and reached a maximum at 10 h. Microglia responded faster than astrocytes. Tumor necrosis factor alpha and interleukin 1 also induced IL-6 mRNA and biological activity in astrocytes, but not in microglia. Among these stimuli, LPS was the most potent inducer of IL-6 production by astrocytes. Our results suggest that different regulatory mechanisms for cytokine production exist in glial cells. The possible roles of astrocytes and microglia in CNS immune responses are also discussed.

Ordering of ceramide formation, caspase activation, and Bax/Bcl-2 expression during etoposide-induced apoptosis in C6 glioma cells

Etoposide (VP-16) a topoisomerase II inhibitor induces apoptosis of tumor cells. The present study was designed to elucidate the mechanisms of etoposide-induced apoptosis in C6 glioma cells. Etoposide induced increased formation of ceramide from sphingomyelin and release of mitochondrial cytochrome c followed by activation of caspase-9 and caspase-3, but not caspase-1. In addition, exposure of cells to etoposide resulted in decreased expression of Bcl-2 with reciprocal increase in Bax protein. z-VAD.FMK, a broad spectrum caspase inhibitor, failed to suppress the etoposide-induced ceramide formation and change of the Bax/Bcl-2 ratio, although it did inhibit etoposide-induced death of C6 cells. Reduced glutathione or N-acetylcysteine, which could reduce ceramide formation by inhibiting sphingomyelinase activity, prevented C6 cells from etoposide-induced apoptosis through blockage of caspase-3 activation and change of the Bax/Bcl-2 ratio. In contrast, the increase in ceramide level by an inhibitor of ceramide glucosyltransferase-1, D-threo-1-phenyl-2-decanoylamino-3-morpholino-1-propanol caused elevation of the Bax/Bcl-2 ratio and potentiation of caspase-3 activation, thereby resulting in enhancement of etoposide-induced apoptosis. Furthermore, cell-permeable exogenous ceramides (C2- and C6-ceramide) induced downregulation of Bcl-2, leading to an increase in the Bax/Bcl-2 ratio and subsequent activation of caspases-9 and -3. Taken together, these results suggest that ceramide may function as a mediator of etoposide-induced apoptosis of C6 glioma cells, which induces increase in the Bax/Bcl-2 ratio followed by release of cytochrome c leading to caspases-9 and -3 activation.

Estrogen receptor antagonist ICI182,780 exacerbates ischemic injury in female mouse

Recent findings in animals emphasize that experimental ischemic brain damage can be strikingly reduced by estrogen: however, the neuroprotective mechanisms are not well understood. It was hypothesized that estrogen signaling via cognate estrogen receptors (ERs) within the vasculature is an important aspect of cerebral ischemic protection in the female brain, in part by amplifying intraischemic cerebral blood flow (CBF). In the present study, the hypothesis that chronic treatment with the pure ER antagonist ICI182,780 (ICI) would increase ischemic brain damage by a blood flow-mediated mechanism was investigated. Adult C57B1/6J mice were pretreated with either subcutaneous ICI (100 microg/day) or oil/ethanol vehicle for 1 week before 2 hours of middle cerebral artery occlusion (MCAO) and 22 hours of reperfusion. End-ischemic regional CBF was evaluated in additional cohorts using [14C]iodoantipyrine autoradiography. Infarction volume as measured by cresyl violet histology was greater in the striatum of ICI-treated females (70 +/- 3% of contralateral striatum vs. 40 +/- 12% in vehicle-treated females). Cortical injury was not enhanced relative to control animals (39 +/- 6% of contralateral cortex in ICI group vs. 27 +/- 8% in vehicle-treated group). Physiologic variables and ischemic reduction of the ipsilateral cortical laser-Doppler flow signal were similar between groups. Further, ICI treatment did not alter end-ischemic cortical or striatal CBF. The deleterious effect of ICI was limited to females, as there were no differences in stroke damage or CBF between male treatment groups. These data suggest that estrogen inhibits ischemic brain injury in striatum of the female by receptor-mediated mechanisms that are not linked to preservation of intraischemic CBF.

Expression of cytokine receptors in cultured neuronal and glial cells

We investigated mRNA expression of cytokine receptors in three different types of glial cells and two neuronal line cells by the RT-PCR method. Microglia expressed mRNA for receptors of IL-3, -4, -6, -7, GM-CSF, and M-CSF. Astrocytes were positive for receptors of IL-6, -7, GM-CSF, and M-CSF. Oligodendrocytes were positive for receptors of IL-3, -4, -7, GM-CSF, and M-CSF. Neuronal cells expressed receptors of IL-6 and GM-CSF with very low levels. This is the first demonstration of cytokine receptor mRNA expression in isolated glial and neuronal cells.

Thiolactomycin, a new antibiotic. I. Taxonomy of the producing organism, fermentation and biological properties

A strain of actinomycetes, isolated from a soil sample, has produced a novel antibiotic (C11H14O2S) containing a unique thiolactone moiety in its molecule. On the basis of taxonomic studies the producing organism was identified as belonging to the genus Nocardia. The antibiotic, named thiolactomycin, exhibits a broad antibacterial spectrum and particularly potent activity against Salmonella, Serratia and Bacteroides. Furthermore, the acute toxicity is weak in experimental animals. These results indicate that thiolactomycin is distinct from other known antibiotics and represents a new type of antibiotic.

Production of interleukin-10 by mouse glial cells in culture

In this study, we examined the production of IL-10 by glial cells in vitro. IL-10 was detected in the culture supernatants of microglia and in the cell lysate of astrocytes by enzyme-linked immunosorbent assay. We also detected IL-10 mRNA and IL-10 receptor mRNA in both microglia and astrocytes. The expression of IL-10 mRNA, as well as the production of IL-10 protein, was enhanced by the stimulation of these cells with lipopolysaccharide(LPS). Recombinant IL-10 effectively suppressed both LPS-induced cytokine production and IFN-gamma-induced class II major histocompatibility complex antigen expression by microglia. These results suggest that IL-10 is produced in the CNS and plays a role as an inhibitory regulator in the CNS cytokine network.

Endoscopic ultrasound-guided fine-needle aspiration biopsy for lymphadenopathy of unknown origin

BACKGROUND AND STUDY AIMS

The diagnosis of mediastinal and intra-abdominal lymphadenopathy is sometimes difficult, especially in patients who have no other primary lesions. Lymphoma is one of the main causes of this condition. Endoscopic ultrasound-guided fine-needle aspiration (EUS-FNA) is a safe and accurate diagnostic procedure for lesions surrounding the gastrointestinal tract. However, diagnosing lymphoma using the EUS-FNA technique remains a diagnostic challenge, due to limitations in the amount of material sampled. The aim of the present study was to evaluate the yield of EUS-FNA biopsy (EUS-FNAB) using a large-gauge needle in patients with mediastinal and intra-abdominal lymphadenopathy of unknown origin, especially in relation to subclassification of the lymphomas.

PATIENTS AND METHODS

Consecutive patients with mediastinal and intra-abdominal lymphadenopathy of unknown origin who were referred between October 2003 and March 2005 were enrolled in the study. EUS-FNAB was carried out using a 19-gauge needle, passing through the esophageal, gastric, and duodenal walls. Pathological diagnoses were made on the basis of histological findings, including immunopathological staining.

RESULTS

A total of 104 patients were included in the study. The locations of the lymph nodes were mediastinal in 50 patients, intra-abdominal in 48 patients, and both mediastinal and intra-abdominal in six patients. The diagnoses made using EUS-FNAB were lymphoma (n = 48), metastasis (n = 16), and benign/reactive (n = 40). The overall accuracy of EUS-FNAB for unknown lymphadenopathy was 98 %, and it was possible to classify the lymphomas in accordance with the World Health Organization classifications in 88 % of cases. No serious complications occurred with the procedure.

CONCLUSIONS

Open thoracic surgery, laparotomy, and other invasive diagnostic procedures such as mediastinoscopy and laparoscopy can now be avoided, as EUS-FNAB is potentially a safe and accurate tool for diagnosing unknown lymphadenopathy, including lymphoma.

Biochemistry of postmortem brains in Parkinson's disease: historical overview and future prospects

Biochemical studies on postmortem brains of patients with Parkinson's disease (PD) have greatly contributed to our understanding of the molecular pathogenesis of this disease. The discovery by 1960 of a dopamine deficiency in the nigro-striatal dopamine region of the PD brain was a landmark in research on PD. At that time we collaborated with Hirotaro Narabayashi and his colleagues in Japan and with Peter Riederer in Germany on the biochemistry of PD by using postmortem brain samples in their brain banks. We found that the activity, mRNA level, and protein content of tyrosine hydroxylase (TH), as well as the levels of the tetrahydrobiopterin (BH4) cofactor of TH and the activity of the BH4-synthesizing enzyme, GTP cyclohydrolase I (GCHI), were markedly decreased in the substantia nigra and striatum in the PD brain. In contrast, the molecular activity (enzyme activity/enzyme protein) of TH was increased, suggesting a compensatory increase in the enzyme activity. The mRNA levels of all four isoforms of human TH (hTH1-hTH4), produced by alternative mRNA splicing, were also markedly decreased. This finding is in contrast to a completely parallel decrease in the activity and protein content of dopamine beta-hydroxylase (DBH) without changes in its molecular activity in cerebrospinal fluid (CSF) in PD. We also found that the activities and/or the levels of the mRNA and protein of aromatic L-amino acid decarboxylase (AADC, DOPA decarboxylase), DBH, phenylethanolamine N-methyltransferase (PNMT), which synthesize dopamine, noradrenaline, and adrenaline, respectively, were also decreased in PD brains, indicating that all catecholamine systems were widely impaired in PD brains. Programmed cell death of the nigro-striatal dopamine neurons in PD has been suggested from the following findings on postmortem brains: (1) increased levels of pro-inflammatory cytokines such as TNF-alpha and IL-6; (2) increased levels of apoptosis-related factors such as TNF-alpha receptor R1 (p 55), soluble Fas and bcl-2, and increased activities of caspases 1 and 3; and (3) decreased levels of neurotrophins such as brain-derived nerve growth factor (BDNF). Immunohistochemical data and the mRNA levels of the above molecules in PD brains supported these biochemical data. We confirmed by double immunofluorescence staining the production of TNF-alpha and IL-6 in activated microglia in the putamen of PD patients. Owing to the recent development of highly sensitive and wide-range analytical methods for quantifying mRNAs and proteins, future assays of the levels of various mRNAs and proteins not only in micro-dissected brain tissues containing neurons and glial cells, but also in single cells from frozen brain slices isolated by laser capture micro-dissection, coupled with toluidine blue, Nissl staining or immunohistochemical staining, should further contribute to the elucidation of the molecular pathogenesis of PD and other neurodegenerative or neuropsychiatric diseases.

Kinetic studies of sequence-specific binding of GCN4-bZIP peptides to DNA strands immobilized on a 27-MHz quartz-crystal microbalance

Specific protein-DNA interaction was studied quantitatively by using a highly sensitive 27-MHz quartz-crystal microbalance (QCM). Biotinylated DNA double strands (21 bp, having a CRE site of 5'ATGACGTCAT3') were immobilized on an avidin-bound QCM surface, and sequence-specific binding of bZIP 56-mer peptides (having both the basic region for binding and the leucine zipper region for dimerization) to the DNA strand on the QCM was observed. The binding amount (Deltam) at the nanogram level and kinetic parameters such as association constants (Ka) and binding and dissociation rate constants (k1 and k-1) could be obtained from time courses of QCM frequency decreases. A bZIP peptide as a dimer was observed to bind sequence-specifically to one DNA strand having a CRE site. Ka values of ss-bZIP, in which the leucine-zipper region of bZIP was substituted by a Cys-Cys linkage, were largely decreased, and the sequence selectivity also disappeared. Ka values obtained by the QCM method showed good agreement with those obtained from the conventional gel mobility shift assay or from circular dichroism spectrum changes. When the specific sequence of the CRE site of DNA strands was partly changed, Ka values decreased by about a half due to the increase of the dissociation rate constant (k-1) independent of the binding rate constant (k1).