Unplugging lateral fenestrations of NALCN reveals a hidden drug binding site within the pore module

The sodium (Na + ) leak channel (NALCN) is a member of the four-domain voltage-gated cation channel family that includes the prototypical voltage-gated sodium and calcium channels (Na V s and Ca V s, respectively). Unlike Na V s and Ca V s, which have four lateral fenestrations that serve as routes for lipophilic compounds to enter the central cavity to modulate channel function, NALCN has bulky residues (W311, L588, M1145 and Y1436) that block these openings. Structural data suggest that oc-cluded lateral fenestrations underlie the pharmacological resistance of NALCN to lipophilic compounds, but functional evidence is lacking. To test this hypothesis, we unplugged the fenestrations of NALCN by substituting the four aforementioned resi-dues with alanine (AAAA) and compared the effects of Na V , Ca V and NALCN block-ers on both wild-type (WT) and AAAA channels. Most compounds behaved in a simi-lar manner on both channels, but phenytoin and 2-aminoethoxydiphenyl borate (2-APB) elicited additional, distinct responses on AAAA channels. Further experiments using single alanine mutants revealed that phenytoin and 2-APB enter the inner cav-ity through distinct fenestrations, implying structural specificity to their modes of ac-cess. Using a combination of computational and functional approaches, we identified amino acid residues critical for 2-APB activity, supporting the existence of drug bind-ing site(s) within the pore region. Intrigued by the activity of 2-APB and its ana-logues, we tested additional compounds containing the diphenylmethane/amine moiety on WT channels. We identified compounds from existing clinically used drugs that exhibited diverse activity, thus expanding the pharmacological toolbox for NALCN. While the low potencies of active compounds reiterate the resistance of NALCN to pharmacological targeting, our findings lay the foundation for rational drug design to develop NALCN modulators with refined properties.

Significance statement

The sodium leak channel (NALCN) is essential for survival: mutations cause life-threatening developmental disorders in humans. However, no treatment is currently available due to the resistance of NALCN to pharmacological targeting. One likely reason is that the lateral fenestrations, a common route for clinically used drugs to enter and block related ion channels, are occluded in NALCN. Using a combination of computational and functional approaches, we unplugged the fenestrations of NALCN which led us to the first molecularly defined drug binding site within the pore region. Besides that, we also identified additional NALCN modulators from existing clinically used therapeutics, thus expanding the pharmacological toolbox for this leak channel.

Immune cell profiling of vaginal blood from patients with early pregnancy bleeding

PROBLEM

Vaginal bleeding during early pregnancy is estimated to occur in 20% of all pregnancies and it is often difficult to predict who will ultimately miscarry. The role of immune cells in early pregnancy loss is poorly understood.

METHOD OF STUDY

In this prospective cohort study, 28 pregnant women presenting with first-trimester vaginal bleeding donated vaginal blood, peripheral venous blood, and saliva during their initial emergency room visit, and at a follow-up. The composition, frequency, and phenotype of immune cells in the vaginal blood were determined using flow cytometry. The proteome of serum and saliva was analyzed with OLINK proximity extension assay and correlated to vaginal immune cell phenotype and outcome of pregnancy. The course and outcome of pregnancies were followed and recorded.

RESULTS

Vaginal blood contained all main immune cell lineages including B cells, NK cells, T cells, and monocytes/macrophages. Notably, vaginal blood immune cells expressed tissue residency markers including CD49a. Women who subsequently miscarried had a higher frequency of vaginal blood CD49a+ NK cells compared to those who did not miscarry, and this correlated with serum levels of granzyme A and H, as well as CSF1, CAIX, and TWEAK. Women in the miscarriage group also had a higher frequency of peripheral blood T cells expressing CD49a.

CONCLUSIONS

Our study provides novel insight into human reproductive immunology in relation to miscarriage. Tissue-resident NK cells in vaginal blood alone or in combination with serological biomarkers hold potential as prognostic factors in the prediction of pregnancy outcome in women with early pregnancy bleedings.

New Ag3 PO4 comparison material for stable oxygen isotope analysis

RATIONALE

A silver phosphate reference material (Ag₃ PO₄ ) for the measurement of stable oxygen isotope compositions is much needed; however, it is not available from the authorities distributing reference materials. This study aims to fill this gap by calibrating a new Ag₃ PO₄ stable isotope comparison material produced by the University of Natural Resources and Life Sciences (BOKU).

METHODS

Aliquots of Ag₃ PO₄ were distributed to four laboratories who frequently measure the δ¹⁸ O value in Ag₃ PO₄ ; the University of Natural Resources and Life Sciences (BOKU), the University of Western Australia (UWA), the University of Helsinki (UH), and the Helmholtz Centre for Environmental Research (UFZ). The instruments used to perform the measurements were high-temperature conversion elemental analysers coupled with continuous flow isotope ratio mass spectrometers. The working gas δ¹⁸ O value was set to 0‰ and the normalization was done by a three-point linear regression using the reference materials IAEA-601, IAEA-602, and NBS127.

RESULTS

The mean δ¹⁸ O value of the new BOKU Ag₃ PO₄ comparison material on the VSMOW-SLAP scale is 13.71‰ and the combined uncertainty is estimated as ±0.34‰. This estimated uncertainty is within the range typical for comparison materials of phosphates and sulphates. Consistent results from the different laboratories probably derived from similar instrumentation, and use of the same reference materials and normalization procedure. The matrix effect of the different reference materials used in this study was deemed negligible.

CONCLUSIONS

The BOKU Ag₃ PO₄ can be used as an alternative comparison material for stable oxygen isotope analysis and is available for stable isotope research laboratories to facilitate calibration.

Temporal and spatial distribution of isotopes in river water in Central Europe: 50 years experience with the Austrian network of isotopes in rivers

The Austrian network of isotopes in rivers comprises about 15 sampling locations and has been operated since 1976. The Danube isotope time series goes back to 1963. The isotopic composition of river water in Central Europe is mainly governed by the isotopic composition of precipitation in the catchment area; evaporation effects play only a minor role. Short-term and long-term isotope signals in precipitation are thus transmitted through the whole catchment. The influence of climatic changes has become observable in the long-term stable isotope time series of precipitation and surface waters. Environmental ³H values were around 8 TU in 2015, short-term ³H pulses up to about 80 TU in the rivers Danube and March were a consequence of releases from nuclear power plants. The complete isotope data series of this network will be included in the Global Network of Isotopes in Rivers database of the International Atomic Energy Agency (IAEA) in 2017. This article comprises a review of 50 years isotope monitoring on rivers and is also intended to provide base information on the (isotope-)hydrological conditions in Central Europe specifically for the end-users of these data, e.g. for modelling hydrological processes. Furthermore, this paper includes the 2006-2015 supplement adding to the Danube isotope set published earlier.

[Social Differences in Physical Activity among Adolescents in Germany: Analyses Based on Information Concerning the Metabolic Equivalent of Task (MET)]

Introduction: Energy consumption, i. e., the metabolic equivalent of task (MET), provides a precise assessment of physical activity (PA). Studies on social inequalities of PA have hardly used this possibility, however. Methods: The analyses are based on the 'Motorik-Modul (MoMo) of the KiGGS study (German Health Interview and Examination Survey for Children and Adolescents) conducted between 2003 and 2006 (n=1 757; age group 11-17 years). PA has been assessed in 3 settings (sport club in school, other sport club, leisure time). 3 dependent variables were distinguished by combining the following criteria: at least 21 MET-hours per week, intensity between 3 and 6 METs, at least 7 hours a week. The main independent variables are: type of school and socioeconomic status (SES) of the parents. 'Two part models' have been used to assess social difference in PA among those who are physically active. Results: PA is much more common in the higher SES groups. Looking at the MET-hours, though, there are just little differences among those who are physically active (regressions coefficient for low vs. high SES: 1.15; 95% conf. interv. 0.99-1.33). Conclusion: Social differences can be seen mainly for the proportion of adolescents being physically active, not for the extent of PA among those who are physically active. Therefore, the central request should be to increase the proportion of adolescents performing any PA in the low SES group.

[Endoprosthetic tumor replacement : Reconstruction of the extensor mechanism and complications]

BACKGROUND

The reconstruction of the extensor mechanism around the knee is an essential part of tumorresection and tumor arthroplasty in orthopaedic oncology for functional rehabilitation of quality of life and daily activities.

OBJECTIVES

Operative procedures, treatment options and management of complications with reconstruction of the extensor mechanism after tumor resection around the knee depend on the type of arthroplasty.

MATERIALS AND METHODS

Description of the different treatment option for extensor deficiency divided into infra- and suprapatellar modalities.

RESULTS

The operative procedure is always an individual decision depending on the size of the tumor and its localisation. The extensor mechanism is reconstructed with autogenic, allogenic or synthetic material in combination with tumor arthroplasty.

CONCLUSIONS

Extensor reconstruction (supra-/infrapatellar) is an essential part of tumor resection and tumor arthroplasty around the knee. Often, low functional results and high levels of complications (arthrofibrosis, rerupture extensor mechanism, periprosthetic joint infection) are seen in these highly demanding cases in orthopaedic oncology.

Analysis of isotopic signals in the Danube River water at Tulln, Austria, based on daily grab samples in 2012

Results of stable isotope measurements (δ(2)H, δ(18)O) of daily grab samples, taken from the Danube River at Tulln (river km 1963) during 2012, show seasonal and short-term variations depending on the climatic/hydrological conditions and changes in the catchment area (temperature changes, heavy rains and snow melt processes). Isotope ratios in river water clearly reflect the isotopic composition of precipitation water in the catchment area since evaporation influences play a minor role. Average δ(2)H and δ(18)O values in 2012 are-78‰ and-11.0‰, respectively, deuterium excess averages 10‰. The entire variation amounts to 1.8‰ in δ(18)O and 15‰ in δ(2)H. Quick changes of the isotopic composition within a few days emphasise the necessity of daily sampling for the investigation of hydrological events, while monthly grab sampling seems sufficient for the investigation of long-term hydro-climatic trends. (3)H results show peaks (half-width 1-2 days, up to about 150 TU) exceeding the regional environmental level of about 9 TU, probably due to releases from nuclear power plants.

Stage-dependent BDNF serum concentrations in Alzheimer’s disease

Alzheimer's disease (AD) is characterized by cognitive decline and loss of neurons in specific brain regions. Recent findings have suggested an involvement of brain-derived neurotrophic factor (BDNF) in the pathogenesis of AD. BDNF is an endogenous protein involved in the maintenance of neuronal function, synaptic plasticity and structural integrity in the adult brain. To our knowledge, the present pilot study assessed for the first time BDNF serum and CSF concentrations in 30 patients with different stages of AD in comparison to 10 age-matched non-demendet controls. AD patients were divided in two groups according to their MMSE score: Group 1 (n = 15) in early stages with MMSE scores >or=21 (mean of 25.5) and Group 2 (n = 15) with more severe stages of dementia with MMSE scores <21 (mean of 13.3). As main results, we found in patients with early stages of probable AD significantly increased BDNF serum concentrations as compared to more severe stages of AD (p < 0.0001) and age-matched healthy controls (p = 0.028). BDNF serum values in all AD patients correlated significantly with MMSE scores (r = 0.486; p < 0.0001). Levels of BDNF were below the detection limit of the assay in unconcentrated CSF samples of AD patients and non-demendet controls.In summary, BDNF serum values are increased in early stages of Alzheimer's disease, which may reflect a compensatory repair mechanism in early neurodegeneration and could also contribute to increased degradation of beta-amyloid (Abeta). During the course of the disease, BDNF is decreasing, which correlates with the severity of dementia. The decrease of BDNF may constitute a lack of trophic support with an increase of Abeta accumulation and thus contribute to progressive degeneration of specific regions in the AD-affected brain. BDNF should be further evaluated as a candidate marker for clinical diagnosis and therapeutic monitoring in Alzheimer's disease.

Diminished production of proinflammatory cytokines in patients with Alzheimer's disease

Cerebral inflammation as well as systemic immunological alterations have been reported in Alzheimer's disease (AD). We examined the production of the proinflammatory cytokines interleukin-6, interleukin-12, interferon-gamma, and tumor necrosis factor-alpha in whole blood cell cultures of AD patients and age-matched controls. The production of all measured cytokines after mitogen stimulation is significantly decreased in the AD group compared to controls. The results reflect an attenuated secretory activity of monocytes/macrophages, but also of T-helper cells. The data sustain the assumption that a systemic, possibly age-related alteration of immune mechanisms may play a pathogenetic role in the development of AD.

Increased serum levels of CD95 in Alzheimer's disease

There is growing evidence for a role of apoptosis in Alzheimer's disease (AD). Recent findings suggest an increased susceptibility of lymphocytes to apoptosis in AD. To prove the hypothesis of systemic alterations in the apoptotic balance in AD, serum and cerebrospinal fluid levels of soluble CD95, which is known to mediate apoptosis, were measured. In the serum, AD patients exhibited significantly higher levels of CD95 than the controls (p = 0.017), suggesting an involvement of peripheral markers in AD.

A method for soluble overexpression of the alpha7 nicotinic acetylcholine receptor extracellular domain

We describe the construction of a soluble protein carrying the N-terminal extracellular domain (ECD) of the alpha7 subunit of the nicotinic acetylcholine receptor. The approach was to fuse the alpha7 ECD at the C and N termini of several monomeric and pentameric soluble carrier proteins and to investigate the soluble expression of the product in Escherichia coli. An initial screening of six carrier proteins resulted in the selection of a fusion protein comprising, from the N to the C terminus, the maltose binding protein, a 17-aa linker containing an enterokinase binding site, and the alpha7 ECD. This protein is soluble upon expression in bacteria and is purified by affinity chromatography. It binds the competitive nicotinic antagonist alpha-bungarotoxin with 2.5 microM affinity and displays a CD spectrum corresponding to a folded protein. The method might be suitable to produce large quantities of protein for crystallization and immunochemical experiments.

Oxaloacetate transport into plant mitochondria

The properties of oxaloacetate (OA) transport into mitochondria from potato (Solanum tuberosum) tuber and pea (Pisum sativum) leaves were studied by measuring the uptake of 14C-labeled OA into liposomes with incorporated mitochondrial membrane proteins preloaded with various dicarboxylates or citrate. OA was found to be transported in an obligatory counterexchange with malate, 2-oxoglutarate, succinate, citrate, or aspartate. Phtalonate inhibited all of these countertransports. OA-malate countertransport was inhibited by 4, 4'-dithiocyanostilbene-2,2'-disulfonate and pyridoxal phosphate, and also by p-chloromercuribenzene sulfonate and mersalyl, indicating that a lysine and a cysteine residue of the translocator protein are involved in the transport. From these and other inhibition studies, we concluded that plant mitochondria contain an OA translocator that differs from all other known mitochondrial translocators. Major functions of this translocator are the export of reducing equivalents from the mitochondria via the malate-OA shuttle and the export of citrate via the citrate-OA shuttle. In the cytosol, citrate can then be converted either into 2-oxoglutarate for use as a carbon skeleton for nitrate assimilation or into acetyl-coenzyme A for use as a precursor for fatty acid elongation or isoprenoid biosynthesis.

Antibrain antibodies in mental disorder: no evidence for antibodies against synaptic membranes

Antibody reactivity in serum to synaptic membranes from human was investigated in major depressive disorder (N = 20), paranoid schizophrenia (N = 20), schizoaffective psychosis (N = 20), and in controls (N = 20) using Western and Immunoblots and ELISA technique. None of the patients showed a significant immune response to synaptic membranes. There was a base-line activity in both controls and patients with antibodies directed to a double band of proteins at 66kD. These antibodies may represent natural autoantibodies. The authors conclude from this and other studies that there is at present no proof of antibrain antibodies in mental disorder.

Evidence for the expression of the triosephosphate translocator gene in green and non-green tissue of tomato and potato

Western blot analysis revealed a cross reaction of an antibody against the spinach triosephosphate translocator with 29 kDa proteins from envelope membranes of plastids from green and red tomato fruits and also of potato tuber amyloplasts. Envelope membranes from potato tubers were isolated from a homogenate of total membranes by isopycnic sucrose density gradient centrifugation. We were able to demonstrate by reverse transcription and sequencing of the PCR product that the mRNA for the triosephosphate translocator in leaves is also present in green and red tomato fruits. The mature protein consists of 330 amino acid residues and is highly homologous to the triosephosphate translocator proteins from potato and tobacco. The PCR product obtained for potato tubers was partly sequenced. It corresponds entirely to the cDNA sequence encoding the potato leaf triosephosphate translocator protein. Evidence for the expression of the triosephosphate translocator gene in various photosynthetic active and inactive tomato tissues (leaf, green fruit, red fruit, root, petal, sepal) and potato tubers was further confirmed by northern blot analysis.

Autoantibody reactivity in serum of patients with Alzheimer's disease and other age-related dementias

Serum antibodies against a series of antigens, including an organ-specific central nervous system (CNS) antigen and the neurotransmitter serotonin, were investigated in 22 patients with Alzheimer's Disease (n=15) and other age-related dementias (n=7) by indirect immunofluorescence assay and enzyme-linked immunosorbent assay. Patients with dementia showed an increase of antibody-positive sera against nuclear antigen, gastric parietal cells, CNS antigen, gangliosides (Gm1), laminin, and keratin. Alzheimer's Disease patients alone exhibited antibodies against CNS antigen. However, the results do not show sufficient specificity and sensitivity for use as a diagnostic indicator.

Induction of GTP-cyclohydrolase I mRNA expression by lectin activation and interferon-gamma treatment in human cells associated with the immune response

The development of tetrahydrobiopterin synthesis during lectin stimulation of resting human T lymphocytes (Kerler et al. [1989] FEBS Lett., 250:622-624), the interferon-gamma induced neopterin production by human monocytes/macrophages (Huber et al. [1984] J. Exp. Med., 160:310-316), and the control of tetrahydrobiopterin synthesis in activated T cells by the synergistic action of interferon-gamma and interleukin 2 (Ziegler et al. [1990] J. Biol. Chem. 265:17026-17030) were previously explained by modulation of the apparent GTP-cyclohydrolase I activation. In this study we demonstrate that increases in GTP-cyclohydrolase I activity which occur after lectin induction and after cytokine treatment correlate with increased steady state mRNA levels specific for this enzyme. The enhancement of interferon-gamma induced enzyme activity in primed T cells by interleukin 2 also corresponds to further increases in mRNA expression. The steady state GTP-cyclohydrolase I mRNA levels in primed T cells, however, do not correlate with the steep decline which follows the culmination of enzyme activity 44 hours after treatment. This indicates that the down-regulation of apparent GTP-cyclohydrolase I activity is caused by posttranslational modification of the protein.

Detection of a novel sepiapterin reductase mRNA: assay of mRNA in various cells and tissues of various species

Fragments of cDNA coding for rat, murine, and human sepiapterin reductase (SR) were amplified by PCR via primer positioning close to the reported 3'-end of the coding region in the rat enzyme. They were sequenced and used as probes for mRNA detection. Northern blot analysis detected two mRNA species for SR. Their sizes were 1.3 and 2.1 kb for rat, 1.3 and 2.3 kb for mouse, and 1.6 and 2.1 kb for human cell lines. Comparison of rat cell lines and rat tissues indicated that in tissues only the 1.3-kb species is present. Washing of the Northern blots under different stringency conditions indicated a more stable interaction of the 1.3-kb mRNA species with the cDNA probe as compared to the 2.3-kb species. The 1.3-kb species corresponds to the reported 28.2-kDa molecular mass of rat SR monomer. SR mRNA expression is absent in the human NK-like cell line YT and in the murine erythroleukemia subclone B8/3, which both lack SR activity. Moreover, the relative mRNA expression correlates with the enzymatic activities of different cell lines within the same species. This indicates that SR activity is regulated by its steady state mRNA levels.

Species and tissue specificity of mammalian GTP cyclohydrolase I messenger RNA

Northern blot analysis of rat RNA from cell lines and isolated organs with a specific rat cDNA probe detected two GTP cyclohydrolase I mRNA species of approx. 1.4 and 3.6 kb. The ratio between these two species varies between 0.6 and 2.4 in different rat organs. Using primers derived from highly conserved regions in the rat and Escherichia coli cDNA sequences a human GTP cyclohydrolase I probe was obtained by means of reverse transcription and PCR (polymerase chain reaction). The human PCR product consisting of 555 bp was cloned and sequenced. It shows a 92% identity with the published sequence of the rat gene. The analysis of various human cell lines with this specific probe shows only one species of GTP cyclohydrolase I mRNA with an approximate size of 3.6 kb.

[Results of electroconvulsive therapy in restrictive indications. A retrospective study of 15 years]

In Tübingen ECT is restricted to severely ill patients who do not respond to other somatic therapies; especially to patients with endogenous depression and pernicious catatonia. Between 1976 and 1990, 45 patients were treated with ECT, of whom 22 suffered from endogenous depression and 10 from pernicious catatonia. Thirteen patients with other diagnoses (schizophrenic and schizoaffective psychoses, borderline schizophrenia and obsessive-compulsive disorder) were treated with ECT for severe depressive states after failure of psychopharmacological therapy. A positive therapeutic response to ECT was observed in 46% of patients with endogenous depression and in all 10 with pernicious catatonia. In the patients with schizophrenia and schizoaffective psychosis, borderline schizophrenia and obsessive-compulsive disorder, an amelioration of the depressive or anxiety syndrome was observed only in individual cases. Side effects of ECT were transit syndromes (20%), reversible amnestic syndromes (20%) and cardiac arrhythmias (6%). According to our results, ECT is highly effective in therapy-resistant endogenous depression and pernicious catatonia, and therefore remains a necessary part of psychiatric therapy.

Control of cell-cycle-associated tetrahydrobiopterin synthesis in rat thymocytes

The cell-cycle progression of rat thymocytes from G0 through G1 to DNA synthesis is associated with a transient synthesis of H4biopterin, the concentration of which reaches a maximum at the time of S-phase entry and then decreases. This synthesis of H4biopterin is controlled by the specific activity of GTP cyclohydrolase I, which peaks in G1/S cells. In contrast, the catalytic activity of sepiapterin reductase remains constant throughout the cell-cycle. At G0 the steady state mRNA levels specific for GTP cyclohydrolase I and sepiapterin reductase, respectively, are below the limits of detection. Both accumulate as the thymocytes progress through the cell-cycle but lack cyclic down regulation. The data indicate that the variations in H4biopterin synthesis during the cell-cycle are caused by growth regulated increase in GTP cyclohydrolase I mRNA expression, with subsequent post-translational inactivation. This latter is likely due to the degree of enzyme phosphorylation.

T-wave response in cervical root lesions

T-wave responses of biceps and triceps brachii muscles were recorded electrophysiologically from 31 normal subjects and 15 patients with unilateral lesions of the cervical C6 or C7 roots. Pathological T-wave responses were found in 11 (73%) patients. Patients with radiological correlate showed electromyographic (EMG) pathology in 60% but a pathological T-wave response in 90%. All patients with radiological correlate also showed pathological electrophysiological tests (EMG or T-wave responses). Electrophysiological measurement of the T-wave response appears to be a potentially useful tool in the diagnosis of cervical radiculopathies.

Control of pteridine biosynthesis in the natural killer-like cell line YT

The natural killer-like cell line YT constitutively expresses GTP-cyclohydrolase activity whereas 6-pyruvoyltetrahydropterin synthase and sepiapterin reductase are absent. The product, dihydroneopterin triphosphate, is dephosphorylated and oxidized causing neopterin to accumulate in the cells. The activities of the H4biopterin synthesizing enzymes are not controlled by IFN-gamma or the synergistic action of both IFN-gamma and IL-2 as has been shown for monocytes/macrophages (Huber C. et al. (1984) J. Exp. Med. 160, 310) and CD4+ T cells, respectively (Ziegler I. et al. (1990) J. Biol. Chem. 265, 17026). Sepiapterin reductase specifically is induced by incubation of the cells with sepiapterin, leaving GTP-cyclohydrolase, 6-pyruvoyltetrahydropterin synthase and other enzymes related to pteridine metabolism (dihydropteridine reductase, dihydrofolate reductase) unaffected. The data indicate that H4biopterin synthesis is individually regulated in the diverse cellular components of the immune system.

The use of protease inhibitors in experimental allergic neuritis

In experimental allergic neuritis (EAN) break-down of myelin is attributed to macrophages, which among other factors contain and secrete proteases. In vitro studies have shown that cathepsin D, an acidic aspartyl endopeptidase, and plasmin can degrade myelin proteins. In order to elucidate a potential therapeutic effect of protease inhibitors we treated Lewis rats, immunized with bovine peripheral nervous system myelin, with epsilon-amino-caproic acid (EACA) or pepstatin. EACA or pepstatin was administered twice daily by intraperitoneal injection beginning on day 6 postimmunization or from the onset of disease (on day 12) through day 24. Compared to saline-treated controls, animals treated with either of the inhibitors showed delayed development of clinical signs and electrophysiological abnormalities. Maximal severity and the further course of disease, however, were not different in control and treated groups. Immunohistological evaluation of sciatic nerve specimens on day 24 postimmunization showed equal numbers of cells positive for ED1 (macrophages) and cathepsin D in all animal groups. There was also no difference in the spontaneous proteolytic activity of the sciatic nerve homogenates at pH 2.8, 5.0, and 7.4. Incubation of the homogenates with pepstatin, however, significantly reduced proteolytic activity at pH 2.8 and 5.0, while EACA had no effect at any pH tested. These results imply that treatment to limit the infiltration of cathepsin D-positive cells or to reduce the induction or activity of cathepsin D may provide a therapeutic avenue for treating inflammatory demyelination of the peripheral nervous system.

Control of tetrahydrobiopterin synthesis in T lymphocytes by synergistic action of interferon-gamma and interleukin-2

The control of (6R)-5,6,7,8-tetrahydrobiopterin (H4biopterin) synthesis in primed T cells was analyzed by using the human T cell leukemia virus type I (HTLV-I)-transformed T cell line MT-2. In contrast to the slowly progressing induction of H4biopterin synthesis during activation of resting T cells, it is completed during a 59-h period and is directed by a synergism of interferon-gamma (IFN-gamma) and interleukin-2 (IL-2). Both GTP cyclohydrolase and (6R)-(1',2'-dioxopropyl)-5,6,7,8-tetrahydropterin synthase activities are induced by IFN-gamma. They are further enhanced by combined treatment with IL-2, which per se is ineffective. Furthermore, the combined treatment synchronizes the time periods of both maximum activities, now extending from 33 to 44 h. This period correlates with high cellular H4biopterin levels. It is preceded by a fast and transient period of H4biopterin increase which depends on the synergistic action of both IFN-gamma and IL-2. It coincides with a transient increase in sepiapterin reductase activity. In contrast to MT-2 cells, HTLV-I-transformed HUT 102 cells constitutively secrete IFN-gamma and express IFN-gamma mRNA. The accumulation of H4biopterin is suppressed by anti-IFN-gamma polyclonal antibody and correlates with constitutive expression of all H4 biopterin-synthesizing enzymes.

Proteolysis of peripheral nerve myelin in acute experimental allergic neuritis

Proteolysis of peripheral nerve myelin was studied in rats with experimental allergic neuritis (EAN). In vitro measurements using rat sciatic nerve homogenate and denatured bovine myelin as a substrate showed two myelin specific enzyme activities at pH 3.8 (inhibited by pepstatin) and pH 5.8 (inhibited by PMSF) in the normal rat and newly appearing activities at pH 2.8 (inhibited by pepstatin) and pH 5.0 (not characterized) in the EAN rat. In EAN the proteolytic activity was not restricted to myelin substrate but degraded total sciatic nerve protein as well. Endogenous sciatic nerve protease at pH 5.8 did not significantly change in activity during the course of disease. On the contrary, activity of acid protease at pH 2.8 corresponded well to the disease. Myelin degradation in EAN, therefore, appears to be mainly due to exogenous non-tissue protease.

The lumazine synthase-riboflavin synthase complex of Bacillus subtilis. Crystallization of reconstituted icosahedral beta-subunit capsids

The lumazine synthase-riboflavin synthase complex (heavy riboflavin synthase) of Bacillus subtilis consists of an icosahedral capsid of 60 beta-subunits containing a core of three alpha-subunits. The enzyme has been purified from the derepressed mutant H 94 of B. subtilis by a novel efficient procedure using column chromatography and preparative crystallization. Beta-Subunits were isolated after dissociation of the enzyme at pH 8.0. Ligand-driven renaturation of beta-subunits yields hollow icosahedral beta 60 capsids which could be crystallized in 1.55 M phosphate, pH 8.7, in three different modifications. A monoclinic modification belongs to space group C2 with unit cell dimensions of a = 235.5, b = 191.2, and c = 165.4 A and alpha = gamma = 90 degrees and beta = 134.4 degrees. The crystals contain two hollow beta 60 particles/unit cell and diffract to approximately 2.8-A resolution. A hexagonal modification has the space group P6(3)22 with unit cell dimensions of a = b = 157.2 and c = 300.8 A and alpha = beta = 90 degrees and gamma = 120 degrees. These cell parameters are similar to the dimensions of hexagonal crystals of native heavy riboflavin synthase (alpha 3 beta 60). A second hexagonal modification shows unit cell parameters of a = b = 156.3 and c = 622.6 A and alpha = beta = 90 degrees and gamma = 120 degrees. The space group of this modification could not be determined unambiguously.

Prednisolone therapy of experimental allergic neuritis in Lewis rats does not induce relapsing or chronic disease

The effects of therapeutic prednisolone treatment on experimental allergic neuritis (EAN) in Lewis rats were evaluated in a controlled clinical and electrophysiological study. Since steroid therapy has been suspected to cause relapsing or chronic disease, monitoring was extended over 200 days. Short-term steroid treatment (5 days of 15 mg/kg prednisolone, n = 8) with sudden steroid withdrawal was compared with long-term application (30 days, beginning at 7.5 mg/kg) in descending dosage (n = 8). The experiment included saline-injected controls (n = 8) and controls for stress possibly exerted by the handling of the animals. Treatment was begun at the onset of clinical signs. The clinical and electrophysiological data indicated that deterioration, recovery and mild (insignificant) relapse (after day 30 and day 108) occurred in all groups at the same time. Both steroid application schemes significantly (p less than 0.03) attenuated the severity and shortened the duration of EAN. Relapse was not aggravated after steroid treatment. The clinical course and electrophysiological findings were unaltered by the experimental procedures and by mild experimental stress.

Riboflavin synthases of Bacillus subtilis. Purification and amino acid sequence of the alpha subunit

Bacillus subtilis has two different riboflavin synthases characterized by the subunit structures alpha3 (light enzyme) and alpha3beta60 (heavy enzyme). The light enzyme was purified by a novel procedure with increased yield and excellent reproducibility. The proposed trimer structure was confirmed by cross-linking experiments with dimethyl suberimidate. Fragments of alpha subunits were prepared by cleavage with cyanogen bromide, trypsin, protease Lys-C, and Staphylococcus aureus protease V8, respectively. Sequences were determined by automated liquid or gas phase Edman degradation. The complete sequence (202 amino acids) was established by direct sequencing of the N terminus and sequencing of overlapping peptides. The sequence shows marked internal homology between the NH2-terminal and COOH-terminal half encompassing 26 identical positions and 23 conservative replacements. This suggests that the protomer forms two structurally similar domains. Since it is known that the enzyme has two binding sites per subunit for the substrate 6,7-dimethyl-8-ribityllumazine, it appears likely that each of the homologous protein domains provides one binding site. The stereochemical features of the enzyme mechanism and the structural relation of the alpha trimer to the beta60 capsid of heavy riboflavin synthase suggest that the six domains corresponding to the alpha subunit trimer are related by pseudo 32 symmetry.

Biochemical and developmental features of experimental phenylketonuria induced by L-ethionine in suckling rats

Suckling rats were injected subcutaneously with doses of L-ethionine (0.1 mumole/g body wt) at intervals of 12 hr. In the latter group, phenylalanine hydroxylase was effectively inhibited in vivo resulting in hyperphenylalaninemia and phenylketonuria. Due to the well-known sex-specific differences in L-ethionine metabolism female rats were much more affected by chronic administration of L-ethionine. The underlying mechanism of enzyme inhibition by ethionine could be disturbed protein synthesis and impaired protein phosphorylation, which was suggested by pronounced decreases in ATP content in liver. In the high dosage group depletions mainly of the branched-chain amino acids and lysine occurred in serum and brain, whereas the concentrations of methionine and tryptophan were increased. Tyrosine tended to be decreased in the course of hyperphenylalaninemia. Hyperphenylalaninemia and other resulting amino acid imbalances obviously impaired brain development during the early postnatal period. Concomitantly with reductions in protein concentrations, the activity of cathepsin D, a major intralysosomal acid proteinase, was increased in brain, suggesting also higher protein catabolism in brain. Side effects of this treatment, however, were higher mortality, loss of body weight, and a general impression of delayed development, resembling a state of undernutrition to some extent. These obvious side effects of ethionine limit the usefulness of ethionine as a suitable model for classic phenylketonuria in suckling rats.

Neuroleptically induced dystonia in Huntington's disease: a case report

A patient with Huntington's disease developed acute dystonia whilst treated with tiapride. Sulpiride and tetrabenazine also induced dystonia. The anticholinergic biperiden depressed the syndrome but worsened psychopathology. Finally a combination of tetrabenazine and clozapine was successful in treatment of both chorea and dystonia. According to this observation, acute dystonia may occur in Huntington's disease as a consequence of neuroleptic treatment.

Role of endoneural cells in experimental allergic neuritis and characterisation of a resident phagocytic cell

Electrophysiological, clinical and histological techniques were used to monitor the time course of events related to experimental allergic neuritis (EAN) in 48 Lewis rats. The primary lesion was found to be paranodal demyelination without cellular infiltration. Endoneural phagocytes derive from hematogenous ED1+ED2- monocytes and possibly from resident ED1-ED2+ monocytic cells, not from Schwann cells and fibroblasts. We demonstrate a population of monocytic Ia-bearing, ED1-ED2+ spindle-shaped cells residing in normal peripheral nerve and provide evidence for their transformation into macrophages in the course of EAN.