Molecular mechanisms for the regulation of the expression and function of muscarinic acetylcholine receptors

The regulation of muscarinic acetylcholine receptor expression and function was investigated in cultured cells and in knockout mice. Muscarinic agonist exposure causes m2 receptor desensitization and sequestration and decreases the expression of cardiac potassium channels. The expression of m2 receptors in chick retina is regulated by a developmentally regulated secreted factor. Mice lacking the m1 receptor exhibit a loss of muscarinic regulation of M-current potassium channel activity and pilocarpine-induced seizures.     

The small urinary calculus: natural course and current treatment concepts

Depending on size, duration of symptoms and their location in the collecting system urinary calculi may pass spontaneously in 16 to 93% of cases. The rate of infection and increase in size of stones in the renal pelvis or calix reaches 70% within months to years. Ureteral stones, however may lead to complications during a period of days to weeks. New minimally invasive treatment modalities have liberalized the indications for early intervention in cases of small stones.     

Antioxidant properties of butein isolated from Dalbergia odorifera

The antioxidant properties of butein, isolated from Dalbergia odorifera T. Chen, were investigated in this study. Butein inhibited iron-induced lipid peroxidation in rat brain homogenate in a concentration-dependent manner with an IC50, 3.3+/-0.4 microM. It was as potent as alpha-tocopherol in reducing the stable free radical diphenyl-2-picrylhydrazyl (DPPH) with an IC0.200, 9.2+/-1.8 microM. It also inhibited the activity of xanthine oxidase with an IC50, 5.9+/-0.3 microM. Besides, butein scavenged the peroxyl radical derived from 2,2-azobis(2-amidinopropane) dihydrochloride (AAPH) in aqueous phase, but not that from 2,2-azobis(2, 4-dimethylvaleronitrile) (AMVN) in hexane. Furthermore, butein inhibited copper-catalyzed oxidation of human low-density lipoprotein (LDL), as measured by conjugated dienes and thiobarbituric acid-reactive substance (TBARS) formations, and electrophoretic mobility in a concentration-dependent manner. Spectral analysis revealed that butein was a chelator of ferrous and copper ions. It is proposed that butein serves as a powerful antioxidant against lipid and LDL peroxidation by its versatile free radical scavenging actions and metal ion chelation.     

Effect of cyclic AMP level reduction on human neutrophil responses to formylated peptides

In an attempt to elucidate the mechanism of development of organ-specific autoimmune lesions resembling human Sj?gren's syndrome of MRL/lpr mice, we have analyzed local cytokine gene expressions and organ-specific autoantibody production in vivo. We have demonstrated that a major proportion of T cells bearing CD4 and V(beta)8 molecules are essentially responsible for triggering the autoimmunity in the salivary glands of MRL/lpr mice. The local cytokine gene expressions including interferon(IFN)-gamma, IL-12(p40) mRNAs were observed during the course of murine Sjogren's syndrome in MRL/lpr autoimmune strain. In particular, a high level of local expressions of IL-12 mRNA was detected earlier in the proinflammatory stage of autoimmune lesions. A significant level of local expression of MHC class-II(I-Ak) mRNA was detected before the onset of inflammatory lesions in the salivary glands, and I-Ak-positive epithelial duct cells were frequently observed in the salivary glands of MRL/lpr mice. In addition, we found the salivary gland-specific autoantibody in sera from MRL/lpr mice with early phase of autoimmune lesions by immunoblot analysis. These results suggest that cytokine gene stimulation and autoantibody production are essentially involved in the development of organ-specific autoimmune lesions in Sj?gren's syndrome of MRL/lpr mice.     

Hyperglycemic levels of glucose inhibit interleukin 1 release from RAW 264.7 murine macrophages by activation of protein kinase C

Diabetic patients with hyperglycemia (high blood glucose) have frequent and persistent bacterial infections linked to significantly diminished bactericidal activity and macrophage function. Interleukin-1 (IL-1), released primarily from activated macrophages, is a key mediator of effective host defense against microorganisms. We observe that hyperglycemic levels of D-glucose (8-20 mM) inhibit the release of IL-1 by lipopolysaccharide-stimulated RAW 264.7 murine macrophage cells. An inhibitor of glucose transport and metabolism, 2-deoxyglucose, prevents this inhibition of IL-1 release. High levels (8-20 mM) of fructose and mannose (but not galactose or L-glucose) also inhibit the release of IL-1 activity, suggesting that metabolism is required for IL-1 inhibition. Immunoprecipitation and activity measurements demonstrate that high glucose levels block the release of IL-1 but do not inhibit IL-1 production. High glucose levels (20 mM) increase protein kinase C (PKC) activity, and inhibitors of PKC block the inhibitory effects of glucose. Phorbol 12-myristate 13-acetate, an agonist of PKC, mimics glucose-induced inhibition of IL-1 release. These results demonstrate that high glucose levels inhibit IL-1 release (but not production) by RAW 264. 7 murine macrophages, and this inhibition is mediated by PKC activation. These studies suggest that persistent infections in hyperglycemic patients may be due to an inhibition of IL-1 release from macrophages.     

The biochemistry of hemolysin toxin activation: characterization of HlyC, an internal protein acyltransferase

Hemolysin toxin produced and secreted by pathogenic Escherichia coli is one of a family of cytolytic, structurally homologous protein toxins known as RTX (repeats in toxin) toxins. RTX toxins are products of a gene cluster, CABD. The A gene product, nontoxic hemolysin (proHlyA), is made toxic by posttranslational fatty acylation of two internal lysine residues. HlyC, the C gene product, is essential for acylation, and acyl-acyl carrier protein (ACP) is the acyl donor. HlyB and HlyD are involved in secretion of the toxin. ProHlyA and HlyC were separately subcloned, expressed, and purified, and acyl-ACPs with diverse radioactive acyl groups were synthesized. With these proteins, the conversion of proHlyA to HlyA by acyl transfer was assayed. Acyl-ACP was the obligate acyl donor. Acyl transfer was catalyzed by HlyC monomer, and an acyl-enzyme intermediate was shown. Reaction was inhibited by ACPSH but not by fatty acid or fatty-acyl CoA. Km and Vmax for HlyA were 0.94 microM and 7.5 pmol of acyl group transferred/min, respectively; Km and Vmax for myristoyl-ACP were 0.48 microM and 6.9 pmol/min. The kinetic parameters of different acyl-ACPs resembled a competitive inhibition as acyl group carbon chain length increased; Km's increased while Vmax's remained unchanged. The different kinetic efficacies in the acyltransferase reaction of the ACPs with different acyl groups contrasted notably with the lytic powers of the corresponding acyl-toxins that they generated.     

Clinical course and treatment of herpetic trigeminal ganglionic neuropathy

45 patients were observed in the periods of both acute herpes zoster and postherpetic neuralgia (PHN). In most of the patients herpetic eruptions were located in the areas of innervation of the first branch of the trigeminal nerve. In acute period of the disease there were used aciclovir, helepin or alpisarinum, antiherpetic immunoglobulin, deoxyribonuclease, non-narcotic analgetics were used. Of 28 patients residual PHN was observed in 6 cases, delayed PHN (during 3 months)--in 2 patients. The PHN development was characteristic for elderly patients, delayed request for medical care, concomitant diseases, eruptions with hemorrhagic component and secondary pyodermia and considerable residual sensory deficit. In therapy of PHN the most effective drugs were amitriptylin, non-narcotic analgetics, anticonvulsants as well as acupuncture and electroacupuncture. Relief of a typical deafferentation of pain syndrome was achieved by means of ultrasonic destruction of the trigeminal nucleus (one case). Early therapy of acute herpes zoster does not prevent completely PHN development, but it decreased considerably probability of its forming as well as the severity of its course.     

Cloning and functional expression of a Drosophila metabotropic glutamate receptor expressed in the embryonic CNS

The excitatory neurotransmitter glutamate plays important roles in the mammalian brain, ranging from synaptic plasticity to memory. To mediate these functions, glutamate activates two types of receptors: ligand-gated channels and metabotropic receptors coupled to G-proteins. Both families of glutamate receptors share no sequence homology and possess original structural features compared with other ligand-gated channels and G-protein-coupled receptors, respectively. Glutamate-gated receptor-channel subunits have already been characterized in invertebrates. Here we report the cloning and functional characterization of an invertebrate metabotropic glutamate receptor (DmGluRA) isolated from Drosophila melanogaster. This receptor displays 45 and 43% amino acid sequence identity with its mammalian homologs mGluR3 and mGluR2, respectively. Moreover, its pharmacology and transduction mechanisms are surprisingly similar to those of mGluR2 and mGluR3. DmGluRA is expressed in the CNS of the late embryo. These results indicate that the original structural features of both glutamate receptor types are conserved from insects to mammals and suggest that the functions of these receptors have been highly conserved during evolution.     

Modeling Salt Water Intrusion in Tanshui River Estuarine System—Case-Study Contrasting Now and Then

A vertical (laterally integrated) two-dimensional numerical model was applied to study the salt water intrusion in the Tanshui River estuarine system, Taiwan. The river system has experienced dramatic changes in the past half century because of human intervention. The construction of two reservoirs and water diversion in the upper reaches of the river system significantly reduces the freshwater inflow. The land subsidence within the Taipei basin and the enlargement of the river constriction at Kuan-Du have lowered the river bed. Both changes have contributed farther to the intrusion of tidal flow and salt water in the upstream direction. The model was reverified with the earliest available hydrographic data measured in 1977. The overall performance of the model is in reasonable agreement with the field data. The model was then used to investigate the change in salt water intrusion as a result of reservoir construction and bathymetric changes in the river system. The model simulation study reveals that significant salinity increases have resulted from the combined changes. It has been speculated by ecological researchers that the long-term increase in salinity might be the driving force altering the aquatic ecosystem structure in the lower reach of the estuary and the Kuan-Du mangrove swamp, particularly the enlargement of the mangrove area and the disappearance of freshwater marshes. However, concrete proof has not been available since no prototype salinity data were available prior to the reservoir construction. This case study offers the first quantitative estimate of the salinity changes due to human interference in this natural system.     

Large travel ultra precision x-y-/spl theta/ motion control of a magnetic-suspension stage

This paper presents an indirect adaptive-control approach and its implementation for realizing large travel ultra precision x-y-theta motion control of a magnetic-suspension stage, which is actuated by ten electromagnets and is capable of six-degrees-of-freedom motion. Feedback linearization of the nonlinear force relationship of the electromagnet in terms of the coil current and the air gap is implemented. Due to modeling errors, perfect feedback linearization is not possible, and parameter variations of the feedback-linearized system are demonstrated through closed-loop system identification. Each axis of the feedback-linearized system is then modeled as a double integrator having gain value depending on the position of the stage and subjected to a disturbance. For the purpose of large travel x-y-theta motion control, an indirect adaptive-control algorithm is designed and implemented for each axis of the feedback-linearized system. The developed control algorithm consists of three procedures: a) real-time parameter estimation; b) model cancellation; and c) nominal linear control. Experimental results demonstrate that the indirect adaptive controllers have superior tracking ability when compared to constant gain robust linear H/sup /spl infin// controllers.