Phorbol ester-induced modulation of agonist binding to alpha-1 adrenergic receptors in bovine aortic membranes

Effects of the protein kinase C-activating phorbol ester, phorbol dibutyrate (PDBu) on the binding behavior of the alpha-1 adrenergic receptor were determined from radioligand binding assays at 25 and 2 degrees C. Membranes prepared from PDBu-treated bovine aorta exhibited a 16% reduction in [3H]prazosin binding capacity, whereas [3H]prazosin affinity was unchanged. This may reflect a role for protein kinase C-mediated receptor phosphorylation in determining receptor turnover and surface density. After PDBu treatment, the affinity of epinephrine for [3H]prazosin sites was altered in two respects. Control membranes exhibited both high and low affinity epinephrine binding (KDH, 20 nM; KDL, 1086 nM) whereas, PDBu-treated membranes exhibited only a single class of low affinity sites (KDL, 655 nM). The inclusion of 5'-guanylylimidodiphosphate caused the loss of high affinity sites in control membranes but had no effect on PDBu-treated membranes (KDL, 681 nM). Thus, protein kinase C blocks the ability of the agonist-receptor complex to couple to a GTP binding regulatory protein. In binding studies conducted at 2 degrees C epinephrine also bound to high (KDH, 34 nM) and low affinity (KDL, 1920 nM) sites although the percentage of high affinity sites was higher (percentage of RH, 80) than at 25 degrees C (percentage of RH, 19). PDBu-treated membranes also exhibited two agonist affinity states in 2 degrees C studies although affinity was slightly reduced (KDH, 74 nM; KDL, 2405 nM). 5'-Guanylylimidodiphosphate was without effect at 2 degrees C. These results indicate that a high affinity agonist binding state can still be achieved after PDBu treatment.(ABSTRACT TRUNCATED AT 250 WORDS)     

A method for collecting semithin epoxy serial sections for light microscopy and 3-D reconstruction

In the three-dimensional reconstruction of neuronal structure, it is imperative that ribbons of semithin or ultrathin sections be obtained. Resin-embedded semithin sections display better structural details than paraffin-embedded sections. The cutting and collecting of long ribbons of resin-embedded semithin sections using a microtome, requires the use of large troughs on glass knives. A simple plastic trough has been described which facilitates the collection of ribbons directly onto a coverslip. As the ribbons are formed, they are floated on a coverslip. The water in the trough is slowly drained through a tubing which is attached to a syringe. The ribbons settle on the coverslip, which is easily removed and placed on a hotplate to dry the sections.     

Current perspectives on the role of liver transplantation for Langerhans cell histiocytosis: A narrative review

Langerhans cell histiocytosis (LCH) is a malignant disease of the histiocytes involving various organ systems. The spectrum of liver involvement in LCH ranges from mild transaminitis to end-stage liver disease. The hallmark of hepatic LCH is secondary sclerosing cholangitis, which manifests due to a progressive destruction of the biliary tree by malignant histiocytes. Chemotherapy remains the mainstay of treatment for active LCH. Early recognition, diagnosis and a systematic approach to the management of LCH can ameliorate the disease process. Nonetheless, the liver involvement in these patients may progress despite the LCH being in remission. Liver transplantation (LT) remains central in the management of such patients. Various facets of the management of LCH, especially those with liver involvement remain unclear. Furthermore, aspects of LT in LCH with regards to the indication, timing and post-LT management, including immunosuppression and adjuvant therapy, remain undefined. This review summarises the current evidence and discusses the practical aspects of the role of LT in the management of LCH.     

Analysis of physicochemical properties for drugs from nature

The chemical structure of a compound has a direct influence on its physical, chemical, and biological properties. The present study describes data pertaining to calculations and statistical analysis of the physicochemical parameters of drugs obtained directly or indirectly from nature. The study projects various physiochemical parameters required for their druggability. The study reveals that most of these drugs fall close to Lipinski’s rule of five. Among the reported physicochemical parameters, the number of aromatic rings is most interesting. Illustrations regarding the same are reported, along with their statistical trends.     

Natural human polyreactive IgM induce apoptosis of lymphoid cell lines and human peripheral blood mononuclear cells

Natural polyreactive IgM autoantibodies, encoded by unmutated germline Ig V genes, represent a major fraction of the normal circulating IgM repertoire. We have previously shown that therapeutic preparation of pooled IgM exerts immunomodulatory effects as assessed by in vitro and in vivo studies. Here, we show that the IgM preparation induces cell death in lymphoblastoid cell lines and in human peripheral blood mononuclear cells. The IgM-induced cell death involved classical features of apoptosis such as nuclear fragmentation and activation of caspases. Treatment of leukemic cells with IgM resulted in the cleavage of poly-(A)DP ribose polymerase, a substrate of caspase, and in a reduction in mitochondrial transmembrane potential during the early period of apoptosis induction. Natural IgM-induced apoptosis was inhibited by soluble Fas molecules and affinity-purified Fas antibodies from pooled IgM preparation induced apoptosis in lymphoblastoid cells, suggesting the involvement of the Fas receptor. Our results suggest a role for normal IgM in controlling cell death and proliferation, and imply a possible therapeutic role for IgM in autoimmune and lymphoproliferative disorders.     

Clinical and biochemical features guiding the diagnostics in neurometabolic cutis laxa

Patients with cutis laxa (CL) have wrinkled, sagging skin with decreased elasticity. Skin symptoms are associated with variable systemic involvement. The most common, genetically highly heterogeneous form of autosomal recessive CL, ARCL2, is frequently associated with variable metabolic and neurological symptoms. Progeroid symptoms, dysmorphic features, hypotonia and psychomotor retardation are highly overlapping in the early phase of these disorders. This makes the genetic diagnosis often challenging. In search for discriminatory symptoms, we prospectively evaluated clinical, neurologic, metabolic and genetic features in our patient cohort referred for suspected ARCL. From a cohort of 26 children, we confirmed mutations in genes associated with ARCL in 16 children (14 probands), including 12 novel mutations. Abnormal glycosylation and gyration abnormalities were mostly, but not always associated with ATP6V0A2 mutations. Epilepsy was most common in ATP6V0A2 defects. Corpus callosum dysgenesis was associated with PYCR1 and ALDH18A1 mutations. Dystonic posturing was discriminatory for PYCR1 and ALDH18A1 defects. Metabolic markers of mitochondrial dysfunction were found in one patient with PYCR1 mutations. So far unreported white matter abnormalities were found associated with GORAB and RIN2 mutations. We describe a large cohort of CL patients with neurologic involvement. Migration defects and corpus callosum hypoplasia were not always diagnostic for a specific genetic defect in CL. All patients with ATP6V0A2 defects had abnormal glycosylation. To conclude, central nervous system and metabolic abnormalities were discriminatory in this genetically heterogeneous group, although not always diagnostic for a certain genetic defect in CL.     

Induction of maturation and activation of human dendritic cells: A mechanism underlying the beneficial effect of <Emphasis Type="Italic">Viscum album</Emphasis>as complimentary therapy in cancer

Background  

Viscum album (VA) preparations have been used as a complimentary therapy in cancer. In addition to their cytotoxic properties, they have also been shown to have immunostimulatory properties. In the present study, we examine the hypothesis that the VA preparations induce activation of human DC that facilitates effective tumor regression.