Faculty Bibliography

OBJECTIVE: To explore the relationship between loss of heterozygosity (LOH) of 5p with the histological phenotype in gastric cancer. METHODS: Eighty pairs of tumor and adjacent normal mucosa samples were collected and genomic DNA was extracted. Total of 17 polymorphic microsatellite markers for 5p were used for LOH analysis. A part of samples were fixed in 10% buffered formalin and stained with H&E. Histological type of gastric cancer was defined according to Lauren's classification. RESULTS: The average informative rate of all seventeen markers was 60.0%. The LOH at least in one locus was detected in 28 of the 80 (35.0%) cases. The highest LOH frequency occurring at D5S2849 (7.77 cM), with LOH frequency of 35.2% (19/54). The minimal LOH region was spanned from 6.67 to 9.41 cM (1.18 Mb, covering 2.7 cM), including D5S417, D5S2849, D5S1492 and D5S2088. In 28 with LOH, 24 (85.7%) cases were of intestinal type, and only 4 cases (14.3%) were of diffuse type. There is significant difference between LOH frequency in intestinal-type and diffuse-type gastric cancers (P < 0.01). Searching the NCBI database disclosed that this minimal deletion region at 5p15.33 covered 3 candidate genes, IRX1, IRX2, and CEI. CONCLUSION: The molecular events in 5p 15.33 may be related with the morphological differentiation and development of gastric cancer. Gastric cancer with LOH of 5p15.33 locus tends to develop in to intestinal type. The cluster of candidate genes in 5p15.33 may be closely implicated in carcinogenesis of intestinal type gastric carcinoma.

Lipid modifications such as palmitoylation or myristoylation target intracellular proteins to cell membranes. Secreted ligands of the Hedgehog and Wnt families are also palmitoylated; this modification, which requires the related transmembrane acyltransferases Rasp and Porcupine, can enhance their secretion, transport, or activity. We show here that rasp is also essential for the developmental functions of Spitz, a ligand for the Drosophila epidermal growth factor receptor (EGFR). In cultured cells, Rasp promotes palmitate addition to the N-terminal cysteine residue of Spitz, and this cysteine is required for Spitz activity in vivo. Palmitoylation reduces Spitz secretion and enhances its plasma membrane association, but does not alter its ability to activate the EGFR in vitro. In vivo, overexpressed unpalmitoylated Spitz has an increased range of action but reduced activity. These data suggest a role for palmitoylation in restricting Spitz diffusion, allowing its local concentration to reach the threshold required for biological function

A central function of telomeres is to prevent chromosome ends from being recognized as DNA double-strand breaks (DSBs). Several proteins involved in processing DSBs associate with telomeres, but the roles of these factors at telomeres are largely unknown. To investigate whether the Mre11/Rad50/Nbs1 (MRN) complex is involved in the generation of proper 3' G-overhangs at human telomere ends, we used RNA interference to decrease expression of MRN and analysed their effects. Reduction of MRN resulted in a transient shortening of G-overhang length in telomerase-positive cells. The terminal nucleotides of both C- and G-rich strands remain unaltered in Mre11-diminished cells, indicating that MRN is not responsible for specifying the final end-processing event. The reduction in overhang length was not seen in telomerase-negative cells, but was observed after the expression of exogenous telomerase, which suggested that the MRN complex might be involved in the recruitment or action of telomerase

Neurotrophins are a unique family of polypeptide growth factors that influence the proliferation, differentiation, survival and death of neuronal and non-neuronal cells. They are essential for the health and well-being of the nervous system. NGF (nerve growth factor), BDNF (brain-derived neurotrophic factor), NT-3 (neurotrophin-3) and NT-4 (neurotrophin-4) also mediate additional higher-order activities, such as learning, memory and behaviour, in addition to their established functions for cell survival. The effects of neurotrophins depend upon their levels of availability, their affinity of binding to transmembrane receptors and the downstream signalling cascades that are stimulated after receptor activation. Alterations in neurotrophin levels have been implicated in neurodegenerative disorders, such as Alzheimer's disease and Huntington's disease, as well as psychiatric disorders, including depression and substance abuse. Difficulties in administering trophic factors have led to the consideration of using small molecules, such as GPCR (G-protein-coupled receptor) ligands, which can participate in transactivation events. In this review, we consider the signalling pathways activated by neurotrophins in both health and disease states

Myelin formation and maintenance depends on the establishment of two structurally and biochemically discernible domains: (a)compact myelin, that is multilamellar stacks of plasma membrane sheets; and (b) cytoplasmic channels that border the compact myelin domains, attach them to the cell body and anchor the myelin sheath to the axonal membrane. To identify proteins involved in the organization of these domains we took advantage of the high lipid content of compact myelin to separate it cleanly from other neural membranes and then used reverse-phase HPLC coupled to Electro-Spray Double Mass Spectrometry('MudPIT') to characterize the proteome of this sample. MudPIT allowed us to sidestep the bias of 2D-PAGE against either highly charged or transmembrane proteins. Thus, of 97 proteins that presented at least two, fully tryptic peptides (a stringent threshold), seven were well known myelin markers, including the mayor CNS myelin proteins: proteolipid protein and myelin basic protein, which are not resolvable by 2D-PAGE. Furthermore, we have confirmed and extended the known compact myelin proteome by 22 proteins and confirmed that CNS and PNS myelinated tracts present Sirtuin 2, a tubulin deacetylase, and Septin7, a small GTPase that is likely to be involved in membrane and cytoplasm partitioning.

Juvenile rheumatoid arthritis is the most common arthritic disease of childhood and a leading cause of childhood disability, affecting an estimated 300,000 US children and adolescents aged < or =16 years. Approximately 10% to 30% of patients experience functional deficits resulting from both the articular and systemic manifestations of their disease, including leg length inequality and deformity, that are often more crippling than joint destruction. Surgical intervention to treat bone and soft-tissue deformity, leg length inequality, and joint destruction is indicated when medical therapy has failed. Synovectomy, soft-tissue release, osteotomy, and epiphysiodesis are used to treat deformity and early joint destruction. Arthroplasty remains the primary therapy for joint destruction, although it is fraught with complications specific to this young patient population

Elevated low-density lipoprotein (LDL) cholesterol plays an important role in the development of atherosclerosis. In part, plasma LDL levels are dependent on cholesterol absorption in the intestine and the rate of intrinsic cholesterol synthesis. Therapy with 3-hydroxy-3-methylglutaryl coenzyme A-reductase inhibitors has often proven to be successful in reducing plasma LDL levels. However, a significant number of patients do not reach their target LDL levels despite statin therapy. As is reviewed, drugs that inhibit cholesterol absorption are a useful adjunct to lipid-lowering therapy by statins. This review discusses the mechanisms involved in intestinal absorption of cholesterol and its transport as potential targets of newer agents that affect cholesterol absorption. The use of bile acid sequestrants and esters of plant stanols, as well as other intestinally active agents for reducing plasma LDL levels, has been limited by side effects and difficulties in patient compliance. In contrast, the new selective cholesterol transporter inhibitor ezetimibe has been demonstrated to reduce plasma LDL alone or in combination with statins without significant adverse effects. In spite of the robust lipid-lowering data with ezetimibe, questions about clinical outcomes, safety, and efficacy in various combinations remain.

The potential roles of vesicular transport and apotransferrin (entering from the blood) in intestinal Fe absorption were investigated using Caco-2 cell monolayers with tight junctions in bicameral chambers as a model. As shown previously, addition of 39 microM apotransferrin (apoTf) to the basolateral fluid during absorption studies markedly stimulated overall transport of 1 microM (59)Fe from the apical to the basal chamber and stimulated its basolateral release from prelabeled cells, implicating endo- and exocytosis. Rates of transport more than doubled. Uptake was also stimulated, but only 20%. Specific inhibitors of aspects of vesicular trafficking were applied to determine their potential effects on uptake, retention, and basolateral (overall) transport of (59)Fe. Nocodazole and 5'-(4-fluorosulfonylbenzoyl)-adenosine each reduced uptake and basolateral transport up to 50%. Brefeldin A inhibited about 10%. Tyrphostin A8 (AG10) reduced uptake 35% but markedly stimulated basolateral efflux, particularly that dependent on apoTf. Cooling of cells to 4 degrees C (which causes depolymerization of microtubules and lowers energy availability) profoundly inhibited uptake and basolateral transfer of Fe (7- to 12-fold). Apical efflux (which was substantial) was not temperature affected. Our results support the involvement of apoTf cycling in intestinal Fe absorption and indicate that as much as half of the iron uses apoTf and non-apoTf-dependent vesicular pathways to cross the basolateral membrane and brush border of enterocytes.