Ligand-independent activation of vascular endothelial growth factor receptor 2 by fluid shear stress regulates activation of endothelial nitric oxide synthase

Fluid shear stress generated by blood flowing over the endothelium is a major determinant of arterial tone, vascular remodeling, and atherogenesis. Nitric oxide (NO) produced by endothelial NO synthase (eNOS) plays an essential role in regulation of vascular function and structure by blood flow, but the molecular mechanisms that transduce mechanical force to eNOS activation are not well understood. In this study, we found that laminar flow (shear stress=12 dyne/cm2) rapidly activates vascular endothelial growth factor receptor 2 (VEGFR2) in a ligand-independent manner and leads to eNOS activation in cultured endothelial cells. Flow-stimulated VEGFR2 recruits phosphoinositide 3-kinase and mediates activation of Akt and eNOS. Inhibiting VEGFR2 kinase with selective inhibitors blocks flow-induced activation of Akt and eNOS and production of NO. Decreasing VEGFR2 expression with antisense VEGFR2 oligonucleotides significantly attenuates activation of Akt and eNOS. Furthermore, Src kinases are involved in flow-stimulated VEGFR2 because inhibiting Src kinases by PP2, a selective inhibitor for Src kinases, abolishes flow-induced VEGFR2 tyrosine phosphorylation and downstream signaling. Finally, we show that inhibiting VEGFR2 kinase significantly reduces flow-mediated NO-dependent arteriolar dilation in vivo. These data identify VEGFR2 as a key mechanotransducer that activates eNOS in response to blood flow.     

A novel emergency medical services-based program to identify and assist older adults in a rural community

Rural-dwelling older adults experience unique challenges related to accessing medical and social services. This article describes the development, implementation, and experience of a novel, community-based program to identify rural-dwelling older adults with unmet medical and social needs that leveraged the existing emergency medical services (EMS) system. The program specifically included geriatrics training for EMS providers; screening of older adult EMS patients for falls, depression, and medication management strategies by EMS providers; communication of EMS findings to community-based case managers; in-home evaluation by case managers; and referral to community resources for medical and social interventions. Measures used to evaluate the program included patient needs identified by EMS or the in-home assessment, referrals provided to patients, and patient satisfaction. EMS screened 1,231 of 1,444 visits to older patients (85%). Of those receiving specific screens, 45% had fall-related, 69% medication management-related, and 20% depression-related needs identified. One hundred and seventy-one eligible EMS patients who could be contacted accepted the in-home assessment. Of the 153 individuals completing the assessment, 91% had identified needs and received referrals or interventions. This project demonstrated that screening by EMS during emergency care for common geriatric syndromes and linkage to case managers is feasible in this rural community, although many will refuse the services. Further patient evaluations by case managers, with subsequent interventions by existing service providers as required, can facilitate the needed linkages between vulnerable rural-dwelling older adults and needed community-based social and medical services.     

Mobilization of early hematopoietic progenitor cells with BB-10010: a genetically engineered variant of human macrophage inflammatory protein- 1 alpha

BB-10010 is a genetically engineered variant of human macrophage inflammatory protein-1 alpha with improved solution properties. We show here that it mobilizes stem cells into the peripheral blood. We investigated the mobilizing effects of BB-10010 on the numbers of circulating 8-day spleen colony-forming units (CFU-S8), CFU-S12, and progenitors with marrow repopulating ability (MRA). A single subcutaneous dose of BB-10010 caused a twofold increase in circulating numbers of CFU-S8, CFU-S12, and MRA 30 minutes after dosing. We also investigated the effects of granulocyte colony-stimulating factor (G- CSF) and the combination of G-CSF with BB-10010 on progenitor mobilization. Two days of G-CSF treatment increased circulating CFU-S8, CFU-S12, and MRA progenitors by 25.7-, 19.8-, and 27.7-fold. A single administration of BB-10010 after 2 days of G-CSF treatment increased circulating CFU-S8, CFU-S12, and MRA even further to 38-, 33-, and 100- fold. Splenectomy resulted in increased circulating progenitor numbers but did not change the pattern of mobilization. Two days of treatment with G-CSF then increased circulating CFU-S8, CFU-S12, and MRA by 64-, 69-, and 32-fold. A single BB-10010 administration after G-CSF treatment further increased them to 85-, 117-, and 140-fold, respectively, compared with control. We conclude that BB-10010 causes a rapid increase in the number of circulating hematopoietic progenitors and further enhances the numbers induced by pretreatment with G-CSF. BB- 10010 preferentially mobilized the more primitive progenitors with marrow repopulating activity, releasing four times the number achieved with G-CSF alone. Translated into a clinical setting, this improvement in progenitor cell mobilization may enhance the efficiency of harvest and the quality of grafts for peripheral blood stem cell transplantation.     

Bacterial lipase and high-fat diets in canine exocrine pancreatic insufficiency: A new therapy of steatorrhea?

BACKGROUND & AIMS: Nutrients and properties of lipases affect survival of lipolytic activity during aboral gastrointestinal transit. Whether different doses and formulations of bacterial lipase and diets affect steatorrhea was tested in pancreatic-insufficient dogs. METHODS: A dose of 0-600,000 IU of powdered and 135,000 and 300,000 IU of liquid bacterial lipase was given with a standard meal to 5 dogs with ligated pancreatic ducts. In 4 dogs, 0 or 300,000 IU (normal 6-hour postprandial amount) of powder bacterial lipase was also given with five meals containing 850 kcal with different nutrient caloric densities (mixture design). Coefficients of fat absorption during 72- hour fecal balance studies were used to assess treatments. RESULTS: With the standard meal, powder bacterial lipase reduced steatorrhea in a dose-dependent manner (P = 0.03), and 135,000 and 300,000 IU of the liquid form decreased steatorrhea more than powder bacterial lipase (P = 0.017 and 0.057, respectively). Coefficients of fat absorption with 300,000 IU of powder bacterial lipase correlated (r2 = 0.79; P < 0.001) with increasing proportions of fat calories in diets. CONCLUSIONS: Liquid bacterial lipase decreases steatorrhea more than powder, and 300,000 IU of powder bacterial lipase ingested with high-fat meals corrects canine pancreatic steatorrhea. The combination of adequate mixing of small amounts (milligrams) of bacterial lipase and high-fat meals abolishes canine steatorrhea and may abolish human pancreatic steatorrhea. (Gastroenterology 1997 Jun;112(6):2048-55)     

Generation of transgenic mice with antithetical KEL1 and KEL2 human blood group antigens on red blood cells

BACKGROUND: KEL1, also known as “K,” is one of the most immunogenic red blood cell (RBC) antigens. KEL2, also known as “k,” differs from KEL1 by a single amino acid. Anti‐Kell system antibodies can lead to significant adverse clinical outcomes in humans, including hemolytic complications in alloimmunized transfusion recipients or in infants of alloimmunized mothers. To provide a platform for in‐depth immunologic studies of alloimmunization and subsequent sequelae, we generated transgenic mice expressing the human KEL1 or KEL2 antigens. STUDY DESIGN AND METHODS: Vectors were created in which cDNAs encoding either KEL1 or KEL2 were regulated by an erythroid specific β‐globin promoter and enhancer. Pronuclear microinjections were carried out into a C57BL6 background, and founder pups were identified by polymerase chain reaction and screened for expression by flow cytometry. RBC life span and antigen stability were assessed by dye labeling RBCs, transfusing into agammaglobulinemic (µMT) recipients, and tracking by flow cytometry. RESULTS: The expression of either KEL1 or KEL2 is RBC specific and first occurs on early RBC precursors. Both KEL1 and KEL2 RBCs have a normal circulatory life span and stable antigen expression. Expression of KEL1 or KEL2 does not result in altered levels of murine Kell, and resulting RBCs have normal hematologic variables. CONCLUSION: The KEL1 and KEL2 mice represent the first murine system of RBC immunity with antithetical antigens, allowing a more precise modeling of human RBC immunology in general and also a platform for development of novel therapeutics to prevent or minimize the dangers of RBC alloimmunization to the KEL1 and KEL2 antigens in particular.     

Does a biological link exist between periodontitis and rheumatoid arthritis?

Periodontitis or Periodontal disease(PD) and Rheumatoid arthritis(RA) are two the most common chronic inflammatory diseases. Periodontitis is a biofilm associated destructive inflammatory disease of the periodontium caused by specific microorganisms. Rheumatoid arthritis is an autoimmune condition and is identified by elevated serum autoantibody titre directed against citrullinated peptides or rheumatoid factor. Periodontitis may involve some elements of autoimmunity. Recent studies have established that PD and RA show a common pathway and could be closely associated through a common dysregulation and dysfunction in inflammatory mechanism. The enzyme peptidyl arginine deiminase(PAD), expressed by Porphyromonas gingivalis(P. gingivalis) is responsible for the enzymatic deimination of arginine residuals to citrulline resulting in protein citrullination and its increased accumulation in RA.Citrullination by PAD may act as a putative biologic link between PD and RA. Association of Human leukocytic antigen-DR4 antigen has been established both with RA and PD. Several interleukins and inflammatory mediators(ILs) and Nuclear factor kappa beta ligand are linked to these common chronic inflammatory diseases. Antibodies directed against heat shock protein(hsp 70 ab) of P. gingivalis, P. melanogenicus and P. intermedia are raised in PD as well as RA. Both the conditions share many pathological and immunological similarities. Bacterial infection, genetic susceptibility, altered immune reaction and inflammatory mediators considered responsible for RA are also associated with PD. So it is plausible that a biological link may exist between PD and RA. Therapies aimed at modifying the expression and effect of inflammatory mediators and effector molecules such as matrix metalloproteinases, proinflammatory cytokines and autoantibodies of structural proteins may probably reduce the severity of both RA and PD.