Alterations in cholinergic and non-cholinergic neurotransmitter receptor densities in transgenic Tg2576 mouse brain with beta-amyloid plaque pathology.

Cholinergic deficits in Alzheimer's disease are accompanied by a number of alterations in other transmitter systems including glutamate, noradrenaline and serotonin, suggesting the involvement also of other neurotransmitter systems in the pathogenesis of the disease. To address the question whether beta-amyloid may contribute to these deficits, brain tissue from transgenic Tg2576 mice with Alzheimer plaque pathology at ages of 5 (still no significant plaque load) and 17 months (moderate to high cortical beta-amyloid plaque load) were examined for a number of cholinergic and non-cholinergic markers. Transgenic mice with no significant plaque load demonstrated reduced hemicholinium-3 (HCh-3) binding to choline uptake sites in anterior brain regions as compared to non-transgenic littermates, while in aged transgenic mice with high number of plaque deposits decreased HCh-3 binding levels were accompanied by increased vesicular acetylcholine transporter binding in selected cortical brain regions. In aged transgenic mice GABA(A), NMDA, AMPA, kainate, and beta-adrenergic as well 5-HT(1A)- and 5-HT(2A)-receptor binding levels were hardly affected, whereas alpha(1)- and alpha(2)-adrenoceptor binding was increased in selected cerebral cortical regions as compared to non-transgenic littermates. The development of changes in both cholinergic and non-cholinergic markers in transgenic Tg2576 mouse brain already before the onset of progressive plaque deposition provides in vivo evidence of a modulatory role of soluble beta-amyloid on cortical neurotransmission and may be referred to the deficits in learning and memory observed in these mice also before significant plaque load.     

Low T3 syndrome and chronic inflammatory rheumatism

For the clarification of pathogenesis and clinical relevance of decreases of the triiodothyronine (T3) level in patients with chronic inflammatory rheumatism in a group of 63 patients with clinically, paraclinically and roentgenologically diagnosed rheumatoid arthritis (59 times) and with SLE (4 times), respectively, parallel were determined parameters of the thyroid gland function and of the rheumatic activity as well as a subtile drug anamnesis for the medication of antirheumatic drugs was established. In 33 of the 63 patients who were included into the study decreases and low normal values, respectively, for the total T3 (TT3 less than 1.5 nmol/l) were found. In comparison to the remaining 30 patients with normal TT3 a typical constellation of paraclinical parameters of the thyroid gland with distinct reduction of TT3 and free T3 (FT3), low normal total T4 (TT4), slight increase of the reverse T3 (rT3), moderate decrease of the basal and stimulated TSH and an only very small restriction of the binding capacity of the thyroid hormone (TBG) were found. A clinically relevant hypothyroidism is thus to be excluded with certainty. Antirheumatic drugs, in particular steroidal ones (glucocorticoids) may on principle also induce such paraclinical constellations, related to the thyroid gland. In our investigations a therapy with antirheumatic drugs is causally scarcely considered, since both in the group of patients with decrease of T3 and without decrease comparable quantities of antirheumatic drugs including glucocorticoids were administered and the cortisol values in the plasma do not differ. The investigations confirm our already formerly expressed supposition that also in rheumatics a "low-T3-syndrome" is existing as it is otherwise described in consumptive extrathyroidal diseases (NTI).(ABSTRACT TRUNCATED AT 250 WORDS)     

Unwanted modification of the thyroid gland by drugs with special reference to nonsteroidal antirheumatic agents

In two retrospective clinical studies was investigated the influence of the modern non-steroidal antirheumatic drugs indometacin and diclofenac (Rewodina) on the thyroid gland and corresponding peripheral hormone parameters. Under longterm treatment with indometacin a moderate strumigenic effect could be observed, which could not clearly be proved under the diclofenac therapy. In all patients with rheumatoid arthritis, independent of the kind of pharmacotherapy, decreased T3-hormone levels were found in normal serum T4-values. The findings are discussed as "low-T3-syndrome" in rheumatoid arthritis, induced by the disease lasting for many years possibly in combination with the long-term therapy with antirheumatic drugs. In a second series of investigations in 75 out of 3,104 patients (2.4%) with a bland struma distinct references to a medicamentous evocation of the enlargement of the thyroid gland were found. Anticonvulsive drugs and the antidepressive drug lithium stood in the first place as inductors of such medicamentous struma. Of the non-steroidal antirheumatic drugs only some cases could be ascribed to phenylbutazone, whereas the more modern preparations indometacin and diclofenac in none of our patients could with certainty be made responsible for a development of struma.     

In vivo [125I]-iodobenzovesamicol binding reflects cortical cholinergic deficiency induced by specific immunolesion of rat basal forebrain cholinergic system

In this study, radiolabeled iodobenzovesamicol (IBVM), which is known to bind with high affinity to the vesicular acetylcholine transporter, was tested for its usefulness in imaging cortical cholinergic deficits in vivo. To induce reductions in cortical cholinergic input, the cholinergic immunotoxin 192IgG-saporin was employed. This has been shown to selectively and efficiently destroy basal forebrain cholinergic neurons in rats. The efficiency of the immunolesion was verified by histochemical acetylcholinesterase staining. [125I]-IBVM binding before and after lesioning was measured using autoradiography. Basal forebrain cholinergic cell loss resulted in a considerable reduction in [125I]-IBVM binding in the cholinoceptive target regions, but not in the striatum and cerebellum, brain regions that do not receive a cholinergic input by the basal forebrain cholinergic nuclei, suggesting that [123I]-IBVM has potential in imaging cortical cholinergic deficits in vivo, at least in animals.     

Structural models for the protein family characterized by gamete surface protein Pfs230 of Plasmodium falciparum

Ps230 is the largest representative of a 10-member family of proteins found in all Plasmodium species. The family is defined by partially conserved, cysteine-rich double domains that are approximately 350 aa in length and have one to three predicted disulfide bridges in each half. In Plasmodium falciparum, the most dangerous human malaria, Pf12 is the smallest member of the family, comprising just one double domain. Pfs230, with 7 double domains, and Pfs48/45 and Pfs47, with 1.5 double domains each, are found on the gamete surfaces and are thus potential candidates for a transmission-blocking vaccine. Fold prediction analyses of the double domains in Pfs230 reveal structural resemblance to SAG1 (surface antigen 1), a surface protein with a double beta-sandwich structure from another apicomplexan parasite, Toxoplasma gondii. Template-directed modeling onto SAG1 clearly establishes the structural link between SAG1 and Pfs230 and produces positions for the cysteines that accord with the disulfide-bonding arrangement predicted for the Pfs230 family in earlier work. A highly clustered region of polymorphisms within the second double domain in Pfs230 maps to one side of the sandwich surface. This observation suggests that this region may be functional and reinforces the validity of these molecular models for the core domains of the Pfs230 family of proteins.     

Heavy chain diseases

Heavy chain diseases (HCDs) are rare B-cell lymphoplasma-cell proliferative disorders characterized by production of truncated monoclonal immunoglobulin heavy chains without associated light chains. HCDs involving the three main immunoglobulin classes have been described; alpha-HCD is the most common and has the most uniform presentation, gamma- and mu-HCDs have variable clinical presentations and histopathologic features. HCDs can be thought of as variant types of non-Hodgkin lymphoma: alpha-HCD presents as an extranodal marginal-zone lymphoma of mucosa-associated lymph-node tissue, gamma-HCD as lymphoplasmacytoid non-Hodgkin lymphoma, and mu-HCD as small lymphocytic non-Hodgkin lymphoma or chronic lymphocytic leukemia. Diagnosis of HCD requires documentation of a deleted immunoglobulin heavy chain without a bound light chain in the serum or urine. Prognosis is variable, and no standardized effective treatment programs are available except for alpha-HCD, which in its early stage may respond to antibiotics.     

Alterations in the responsiveness of senescent cells to growth factors

Our studies have led us to conclude that senescent cells respond to growth factors in much the same way, in part, as young cells. The receptor systems are largely unchanged with age, although some subtle modifications do occur. Furthermore, many of the early growth factor initiated events occur in a similar way in both young and old cells. This has led us to theorize that senescent cells are not arrested like mitogen-deprived young cells. Rather, they become blocked at a new arrest point in late G1 just prior to entry into DNA synthesis.     

Profiling receptor tyrosine kinase activation by using Ab microarrays

Signal transduction in mammalian cells is mediated by complex networks of interacting proteins. Understanding these networks at a circuit level requires devices to measure the amounts and activities of multiple proteins in a rapid and accurate manner. Ab microarrays have previously been applied to the quantification of labeled recombinant proteins and proteins in serum. The development of methods to analyze intracellular signaling molecules on microarrays would make Ab arrays widely useful in systems biology. Here we describe the fabrication of multiplex Ab arrays sensitive to the amounts and modification states of signal transduction proteins in crude cell lysates and the integration of these arrays with 96-well microtiter plate technology to create microarrays in microplates. We apply the Ab arrays to monitoring the activation, uptake, and signaling of ErbB receptor tyrosine kinases in human tumor cell lines. Data obtained from multicolor ratiometric microarrays correlate well with data obtained by using traditional approaches, but the arrays are faster and simpler to use. The integration of microplate and microarray methods for crude cell lysates should make it possible to identify and analyze small molecule inhibitors of signal transduction processes with unprecedented speed and precision. We demonstrate the future potential of this approach by characterizing the action of the epidermal growth factor receptor inhibitor PD153035 on cells by using Ab arrays; direct scale-up to array-based screening in 96- and 384-well plates should allow small molecules to be identified with specific inhibitory profiles against a signaling network.