Graves' disease: immunological and immunogenetic indicators of relapse

The use of measurements of antibody to the thyroid stimulating hormone receptor and HLA-DR3 phenotype for predicting relapse of hyperthyroidism in patients with Graves'' disease receiving medical treatment is controversial. Fifty eight new patients with Graves'' disease were followed up prospectively for up to 96 months after treatment with antithyroid drugs for 12 months. The presence of antibody to the thyroid stimulating hormone receptor before the start of treatment, measured as immunoglobulins inhibiting binding of thyroid stimulating hormone, was not associated with relapse. Patients who remained positive for antibodies after treatment tended to relapse within six months, but no relation with long term relapse was found. HLA-Cw7 but not HLA-DR3 was significantly associated with relapse. The presence of HLA-DR4 was significantly associated with remission and with absence of antibodies to thyroid stimulating hormone receptor. HLA-DR4 may therefore protect against relapse of thyrotoxicosis by immunomodulation triggered by antithyroid drugs, which results in the synthesis of antibodies to the thyroid stimulating hormone receptor being inhibited.     

Advanced glycation endproducts influence the mRNA expression of RAGE, RANKL and various osteoblastic genes in human osteoblasts

Glycation reactions resulting in the generation and accumulation of advanced glycation endproducts (AGEs) are potential mechanisms by which bone protein may be altered in vivo. AGEs accumulate in the bone increasingly with age come into close contact with osteoblasts or osteoclasts. The direct effect of AGEs on bone cells has not been thoroughly investigated. This study aimed to examine whether glycated bovine serum albumin (AGE - BSA) as an AGE modulate the mRNA expression of various genes in primary human osteoblast cultures. The following parameters were included: RAGE (receptor for AGEs), alkaline phosphatase, osteocalcin, osterix and RANKL (receptor activator of nuclear factor-kappaB ligand). Primary human osteoblast cultures were obtained from bone specimens of six patients with osteoarthrosis. Human osteoblasts were treated in AGE - BSA or control-BSA (non-glycated BSA) containing medium (5 mg/ml each) over a time course of seven days. After RT-PCR the mRNA expression was measured by real-time PCR. Related to control - BSA exposure, the mRNA expression of RAGE, RANKL and osterix increased during AGE - BSA treament. For alkaline phosphatase and osteocalcin a tendency of down-regulation was found. In summary, the study presents evidence that advanced glycation end products accumulated in bone alter osteoblasts by activation the AGE - RAGE pathway (RAGE mRNA up-regulation), inducing enhanced osteoclastogenesis (RANKL mRNA up-regulation) and impaired matrix mineralization (down-regulation of alkaline phosphatase and osteocalcin mRNA). Thus, AGEs may play a functional role in the development of bone diseases (e.g. osteoporosis).     

The WI-1 adhesin blocks phagocyte TNF-alpha production, imparting pathogenicity on Blastomyces dermatitidis

The WI-1 adhesin is indispensable for pathogenicity of Blastomyces dermatitidis and is thought to promote pulmonary infection by fixing yeast to lung tissue and cells. Recent findings suggest that WI-1 confers pathogenicity by mechanisms in addition to adherence. Here, we investigated whether WI-1 modulates host immunity by altering production of pro-inflammatory cytokines. Production of TNF-alpha in lung alveolar fluids of mice infected with B. dermatitidis was severalfold higher for WI-1 knockout yeast compared with wild-type yeast, and in vitro coculture of unseparated lung cells with these isogenic yeast disclosed similar differences. Upon coculture with purified macrophages and neutrophils, wild-type yeast blocked TNF-alpha production, yet WI-1 knockout yeast stimulated production. Coating knockout yeast with purified WI-1 converted them from stimulating TNF-alpha production to inhibiting production. Addition of purified WI-1 into stimulated phagocyte cultures led to concentration-dependent inhibition of TNF-alpha production. Neutralization of TNF-alpha in vivo exacerbated experimental pulmonary infection, particularly for the nonpathogenic WI-1 knockout yeast. Inducing increased TNF-alpha levels in the lung by adenovirus-vectored gene therapy controlled infection with wild-type yeast. Thus, the WI-1 adhesin on yeast modulates host immunity through blocking TNF-alpha production by phagocytes, which fosters progression of pulmonary infection.     

Anaerobic Sulfide Oxidation with Nitrate by a Freshwater Beggiatoa Enrichment Culture

A lithotrophic freshwater Beggiatoa strain was enriched in O₂-H₂S gradient tubes to investigate its ability to oxidize sulfide with NO₃⁻ as an alternative electron acceptor. The gradient tubes contained different NO₃⁻ concentrations, and the chemotactic response of the Beggiatoa mats was observed. The effects of the Beggiatoa sp. on vertical gradients of O₂, H₂S, pH, and NO₃⁻ were determined with microsensors. The more NO₃⁻ that was added to the agar, the deeper the Beggiatoa filaments glided into anoxic agar layers, suggesting that the Beggiatoa sp. used NO₃⁻ to oxidize sulfide at depths below the depth that O₂ penetrated. In the presence of NO₃⁻ Beggiatoa formed thick mats (>8 mm), compared to the thin mats (ca. 0.4 mm) that were formed when no NO₃⁻ was added. These thick mats spatially separated O₂ and sulfide but not NO₃⁻ and sulfide, and therefore NO₃⁻ must have served as the electron acceptor for sulfide oxidation. This interpretation is consistent with a fourfold-lower O₂ flux and a twofold-higher sulfide flux into the NO₃⁻-exposed mats compared to the fluxes for controls without NO₃⁻. Additionally, a pronounced pH maximum was observed within the Beggiatoa mat; such a pH maximum is known to occur when sulfide is oxidized to S⁰ with NO₃⁻ as the electron acceptor.     

Insulin modulates hippocampal activity-dependent synaptic plasticity in a N-methyl-d-aspartate receptor and phosphatidyl-inositol-3-kinase-dependent manner

Insulin and its receptor are both present in the central nervous system and are implicated in neuronal survival and hippocampal synaptic plasticity. Here we show that insulin activates phosphatidylinositol 3-kinase (PI3K) and protein kinase B (PKB), and results in an induction of long-term depression (LTD) in hippocampal CA1 neurones. Evaluation of the frequency-response curve of synaptic plasticity revealed that insulin induced LTD at 0.033 Hz and LTP at 10 Hz, whereas in the absence of insulin, 1 Hz induced LTD and 100 Hz induced LTP. LTD induction in the presence of insulin required low frequency synaptic stimulation (0.033 Hz) and blockade of GABAergic transmission. The LTD or LTP induced in the presence of insulin was N-methyl-d-aspartate (NMDA) receptor specific as it could be inhibited by alpha-amino-5-phosphonopentanoic acid (APV), a specific NMDA receptor antagonist. LTD induction was also facilitated by lowering the extracellular Mg(2+) concentration, indicating an involvement of NMDA receptors. Inhibition of PI3K signalling or discontinuing synaptic stimulation also prevented this LTD. These results show that insulin modulates activity-dependent synaptic plasticity, which requires activation of NMDA receptors and the PI3K pathway. The results obtained provide a mechanistic link between insulin and synaptic plasticity, and explain how insulin functions as a neuromodulator.     

Modulation of the activity of phosphoenolypyruvate carboxylase during potassium-induced swelling of guard-cell protoplasts of Vicia faba L. after light and dark treatments

Phosphoenolpyruvate carboxylase (PEPCase; EC 4.1.1.31) activity was found to be modulated by light and darkness when measured in the presence of K⁺, which had been added to induce swelling of guard-cell protoplasts (GCPs) from Vicia faba L., whereas no modulation was detected in the absence of K⁺ (PEPcase activity remained constant at 1.5±0.15 pmol PEP metabolized · GCP^–1 ·h^–1; subsequently, pmol GCP^–1 ·h^–1 will be used). The activity of PEPCase increased by 100% (from 1.5 to 3 pmol·protoplast^–1·h^–1) in darkness and by 200% (from 1.7 to 5 pmol·protoplast^–1· h^–1) in light and oscillations in activity of these magnitudes were repeated at intervals of 2 min (dark) and 2.5 min (light) for a period of 10 min during K⁺-induced increase in the volume of GCPs. The oscillations were reflected in changes in malate-pool sizes determined in plastids, mitochondria and the supernatant fraction (consisting of the cytosol and the vacuole). Malate probably functioned as a mitochondrial substrate, thus supplying ATP for K⁺ uptake and the swelling of the protoplasts. On the basis of the present paper and previous results (H. Schnabl and B. Michalke 1988, Life Sci. Adv. Plant Physiol. 7, 203–207) involving adenine nucleotidepool sizes in fractionated GCPs, a model is proposed to explain the cause-effect relationship between K⁺, PEPCase, the cytosolic and mitochondrial malate levels and ATP levels during the K⁺-induced increase of GCP volume.Abbreviations GCP dtguard-cell protoplast - PEP phosphoenol-pyruvate - PEPCase PEP carboxylase The authors thank Professor Hermann Schnabl, University of Stuttgart (FRG), for his assistance in applying the graph theory analysis. This work was supported by Deutsche Forschungsgemeinschaft to H.S.     

Temperature rather than photoperiod controls growth cessation and dormancy in Sorbus species

Environmental regulation of growth and dormancy of four Sorbus genotypes was studied in controlled environments. Emphasis was placed on assessment of the presence and nature of the deficient photoperiodic dormancy regulation system that has previously been reported for some woody Rosaceae species. Two genotypes of Sorbus aucuparia L. maintained indeterminate growth for 8 weeks and 9 weeks at temperatures of 15 °C and 21 °C in both 20 h and 10 h photoperiods, while at 9 °C, in the same photoperiodic conditions, they immediately ceased growing. At the higher temperatures, initiation of new leaves (nodes) was unaffected by photoperiod, while internode elongation was significantly enhanced by long days (LD). However, even after prolonged exposure to 9 °C, most plants resumed growth when moved to high temperature and LD, indicating a shallow state of dormancy. Seedlings of Sorbus intermedia (J. F. Ehrh.) Pers. and micro-propagated plantlets of S. commixta Hedl. 'Dodong' were also unaffected by photoperiod during primary growth, but failed to elongate and gradually became dormant regardless of temperature and day-length conditions. However, after chilling and breaking of dormancy, the plants elongated vigorously but changed to a determinate mode of growth. Furthermore, a temperature of 9 °C was found to be fully effective for breaking dormancy in S. intermedia plants. It is concluded that deficient photoperiodic dormancy control seems widespread in the Rosaceae and that, in such plants, both dormancy induction and release is brought about by low temperature. The potential impacts of climate change on such trees are discussed.     

A patient with an interstitial deletion in Xp22.3 locates the gene for X-linked recessive chondrodysplasia punctata to within a one megabase interval

A male patient carrying an interstitial deletion in Xp22.3 and affected by Kallmann syndrome, X-linked ichthyosis and mental retardation, but without chondrodysplasia punctata or short stature, was investigated with molecular probes from the distal Xp22.3 region. By means of a novel probe, M115, from the relevant region, the distal deletion breakpoint was shown to be between 3.18 and 3.57 Mb from Xptel. As the patient is not affected by X-linked recessive chondrodysplasia punctata, the gene for this disease can therefore be located to within an interval of less than one megabase proximal to the pseudoautosomal boundary. If the chondrodysplasia punctata gene is associated with a CpG island, this leaves only two islands at 2760 and 3180 kb from the Xp telomere as the most promising candidate sites for this gene.     

Esterase-D polymorphism in Assam by cellulose acetate electrophoresis

Summary With the help of a simplifed and quick method, cellulose acetate electrophoresis, the phenotypes of esterase D were determined in an Assamese population. The gene frequencies of Es D¹ were 0.7263 and 0.2737 for Es D².

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Zusammenfassung In einer Stichprobe aus Assam wurde mit Hilfe einer einfachen und schnellen Methode, der Cellulose-Acetat-Elektrophorese, die Bestimmung der Esterase D-Phänotypen durchgeführt. Die Genfrequenzen wurden für Es D¹ zu 0,.7263 und für Es D² zu 0.2737 bestimmt.

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Supported by the Deutsche Forschungsgemeinschaft, the Stiftung VW and the Fonds der Chemischen Industries.