bluuebunny/crossref_metadata_2025_split huggingface dataset:
Decreased Deformability of Polymorphonuclear Leukocytes in Diabetic Cats
Authors: Braun Rod D. , Fisher Timothy C. , Meiselman Herbert J. , Hatchell Diane L. 
Published: April 2008

ABSTRACTObjective: Polymorphonuclear leukocytes (PMN) have been found to be less deformable in humans with non‐insulin‐dependent diabetes. It has therefore been hypothesized that white blood cells (WBC) may affect the development of diabetic microangiopathy. This study was designed to determine whether PMN or small and large lymphocytes were less deformable in a large animal model of diabetes—chronically hyperglycemic pancreatectomized cats.Methods: Venous blood was withdrawn from 13 normal and 14 diabetic cats. The diabetic cats had been kept in poor metabolic control since their pancreatectomy (7‐113 months before this study). Blood cell counts, hemoglobin concentration, hematocrit, erythrocyte volume, and WBC differential counts were obtained from the blood samples. Purified mononuclear WBC and PMN fractions were obtained by separating the blood on a discontinuous Percoll gradient. The deformability of each cell fraction was determined using a Cell Transit Analyzer (ABX, Montpellier, France) that measures the transit time of cells through 7.5‐μm pores. By varying the sampling rate of the CTA and the pressure difference across the filter, the subpopulations of the mononuclear fractions (small and large lymphocytes) could be identified and each subpopulation analyzed separately.Results: Median transit times for the PMN and small lymphocytes were significantly greater for the diabetic cats, but no difference was found in the large lymphocyte fractions.Conclusions: These results are in accordance with the finding that PMN are less deformable in humans with diabetes. We also showed that the small lymphocytes from diabetic cats have prolonged transit times. The results suggest that PMN may contribute to the development of microangiopathies like diabetic retinopathy. Diabetic cats may prove useful for testing potential therapies to improve WBC deformability.
Apigenin Inhibits Tumor Necrosis Factor‐Induced Intercellular Adhesion Molecule‐1 Upregulation In Vivo
Authors: Panés Julián , Gerritsen Mary E. , Anderson Donald C. , Miyasaka Masayuki , Granger D. Neil 
Published: April 2008

ABSTRACTObjective: Apigenin is a flavonoid that effectively blocks intercellular adhesion molecule‐1 (ICAM‐1) upregulation and leukocyte adhesion in response to cytokines in vitro. In the present study, we characterized the effects of tumor necrosis factor (TNF) on ICAM‐1 expression in different tissues of the rat. We then assessed whether apigenin alters this response.Methods: ICAM‐1 expression was measured under baseline conditions or 5 h after treatment with rTNF. We used 125I‐labeled anti‐rat ICAM‐1 monoclonal antibody (mAb) and an isotype‐matched control mAb labeled with 131I to correct for nonspecific accumulation of the binding mAb. Animals were pretreated with either placebo, apigenin, narigenin (a flavonoid without inhibitory effect in vitro), or vehicle. Additional groups of animals were treated with either allopurinol, glutathione, dimethyl‐thiourea, or an anti‐CD18 monoclonal antibody in order to assess possible actions of flavonoids that were mediated via free radical scavenging or through interference with neutrophil function.Results: Treatment with rTNF resulted in a marked increase in ICAM‐1 expression in all organs studied. The magnitude of the response varied in different organs and increases ranged from onefold (lung) to threefold (muscle). Treatment with apigenin blocked ICAM‐1 upregulation in organs with low to intermediate responses to rTNF and it significantly attenuated the increased ICAM‐1 expression in organs that normally exhibit more marked upregulation. Treatment with narigenin or vehicle did not affect rTNF‐induced ICAM‐1 upregulation in all tissues studied. Pretreat‐ment with either allopurinol, free radical scavengers, or anti‐CD18 monoclonal antibody did not affect the ICAM‐1 upregulatory response to rTNF.Conclusions: TNF‐induced ICAM‐1 upregulation in vivo effectively is blocked by apigenin through a mechanism that is unrelated to free radical scavenging or leukocyte function.
Intravital Microscopy of the Peripheral Lymph Node Microcirculation in Mice
Authors: Von Andrian Ulrich H. 
Published: April 2008

ABSTRACTObjective: The purpose of this study was to develop a model for microscopic in situ observation of the murine peripheral lymph node (LN) microcirculation and to characterize the function of the lymphocyte homing receptor L‐selectin (CD62L) and the peripheral node addressin (PNAd). The latter is a high‐affinity ligand for L‐selectin in LN high endothelial venules (HEV).Methods: The subiliac (superficial inguinal) LN was microsurgically dissected in anesthetized adult mice. The nodal microvascular architecture and venular hemodynamics were characterized by bright field and epifluorescence video microscopy. L1‐2 pre‐B cells that were either mock transfected (L1‐2Vector) or stably transfected to express human L‐selectin (L1‐2L‐selection) were labeled fluorescently and injected into a feeding artery. Cell adhesion in LN venules was studied in both the presence and absence of neutralizing monoclonal antibodies (MAb) to PNAd and L‐selectin.Results: The preparation allowed a detailed analysis of hemodynamic parameters and leukocyte adhesion in LN microvessels. L1‐2Vector cells did not interact with LN microvessels. In contrast, L1‐2L‐selectin cells rolled efficiently in venules but not in arterioles or capillaries. Rolling was most prominent in subcortical HEV (orders III to V) and was less frequent but consistently detectable in downstream medullary and hilus venules (orders I and II). Rolling interactions were abrogated by MAb DREG‐56 to the lectin domain of L‐selectin and were markedly reduced by the anti‐PNAd MAb MECA‐79.Conclusions: The present study develops a new intravital microscopy model for in vivo visualization of leukocyte interactions with microvessels in murine LN. The preparation permitted an analysis of biophysical and molecular mechanisms of leukocyte adhesion to high endothelial cells. The data support the concept that L‐selectin and PNAd are the predominant receptor/ligand pair responsible for lymphocyte rolling in HEV. The model will be useful for high‐resolution analysis of intra‐ and extravascular events in living LN.
Neutrophil‐Endothelial Interactions in a Cell‐Column Model of the Microvasculature: Effects of fMLP
Authors: Haselton F. R. , Woodall J. H. , Alexander J. S. 
Published: April 2008

ABSTRACTObjective: The purpose of this study was to develop an in vitro model which, compared to stagnant two‐chamber systems, is more analogous to the rheological conditions found in the vasculature and permits near simultaneous measurement of polymorphonuclear leukocytes (PMN) entrapment and endothelial monolayer permeability.Methods: A previously described cell‐column model of the vasculature was perfused with 2 ± 106 PMN/ml at an average fluid velocity of 0.09 cm/s and an average estimated endothelial surface shear stress of 4.5 dyne/cm2 for a total of 60 min. PMN entrapment was estimated from counts of PMN in this recirculating system. Bovine endothelial permeability was estimated from an indicator dilution analysis of the three co‐injected dyes: blue dextran (molecular weight [MW]) 2 ± 106), sodium fluorescein (MW 342) and cyanocobalamin (MW 1355).Results: Circulation of PMN through cell‐columns did not activate PMN, although the number of circulating PMN decreased at a rate of 14% per 65 cm2 of endothelial surface in the first 15 min. Endothelial cell monolayer permeability did not change within 60 min. Addition of formyl‐methionyl‐leucyl‐phenylalanine (fMLP) (lO−5 M) activated PMN and significandy increased entrapment of circulating PMN to 27% per 65 cm2 in the first 15 min. Although the percentage of circulating PMN entrapped increased, endothelial monolayer permeability was not increased by either the addition of 10−5M fMLP or PMN + fMLP to the cell‐column perfusate.Conclusions: Over the 60‐min period studied, entrapment of PMN within a recirculating model of die microvasculature was not associated with an increase in endothelial permeability even after PMN stimulation with fMLP.
Cytokeratin Expression and Hyaluronic Acid Production in Cultures of Human Synovial Microvascular Endothelial Cells: Influence of Cytokines and Growth Factors
Authors: Carley William W. , Szczepanski Andrew , Gerritsen Mary E. 
Published: April 2008

ABSTRACT Objectives: To isolate and characterize human synovial endothelial cells and to determine the effects of cytokines and fibroblast growth factor on human synovial endothelial (HSE) cell hyaluronic acid production. Methods: Endothelial cells were isolated from primary cultures of human synovial cells by fluorescent activated cell sorting based on the incorporation of a fluorescent derivative of acetylated low‐density lipoprotein (DiI‐Ac‐LDL). Identity of endothelial cells was confirmed by positive immunostaining for von Willebrand factor (vWf), cytokeratins, endoglin, and reactivity with the lectin ulex europeaus agglutinin (UEA). Hyaluronic acid production was measured by a radioligand‐binding assay. Results: HSE cells were isolated and maintained in long‐term culture. The identity of the cultured cells as endothelial was based on uniform uptake of a (DiI‐Ac‐LDL), immunoreactivity for vWf, and endoglin and the binding of the lectin UEA. In addition, small blood vessels in the synovium were stained selectively with anticytokeratin antibodies K4.62 (cytokeratin 19 specific) and K8.13 (reactive for cytokines 1, 5, 6, 7, 8, 10, 11, and 18). Isolated HSE cells also demonstrated immunoreactivity with these cytokeratin antibodies. The cytokeratins identified by the monoclonal antibody clone K8.13 demonstrated a diffuse, fibrillar staining pattern. The cytokeratin distribution revealed with monoclonal antibody K4.62 (cytokeratin 19) was also fibrillar; however, the majority of cells also demonstrated numerous punctate cytoplasmic vesicular structures. Treatment of HSE cells with interleukin‐1α (IL‐1α) or acidic fibroblast growth factor (aFGF), but not tumor necrosis factor (TNFα), dramatically reduced the vesicular structures staining with the K4.62 antibody. HSE cells produced hyaluronic acid (HA) at a constitutive rate of 200–800 ng/105 cells/24 h, which could be upregulated when the cells were incubated with either IL‐1α or aFGF. HA production was not significantly increased when HSE cells were incubated with TNFα, IL‐4 or interferon‐γ. Conclusions: Synovial microvascular endothelial cells produce and secrete HA and endothelial HA secretion is upregulated by IL‐1 and aFGF. IL‐1 and aFGF also reduce the number of vesicular‐like structures immunoreactive with a monoclonal antibody to cytokeratin 19. These studies suggest that cytokine stimulation of local endothelial secretion and/or accumulation of HA may influence leukocyte adhesion to the synovial endothelium.
Degranulation of Mast Cells in the Chick Chorioallantoic Membrane Does Not Increase Macromolecular Extravasation During Normal Angiogenesis
Authors: Rizzo Victor , Shumko John Z. , DeFouw David O. 
Published: April 2008

ABSTRACT Objective: To test the hypothesis that stimulation of mast cell degranulation during normal angiogenesis in the chick chorioallantoic membrane (CAM) serves to acutely activate macromolecular transendothelial pathways. Methods: Using shell‐less cultures of 6‐day‐old chick embryos, efflux of fluorescein isothiocyanate (FITC)‐dextran 150 from CAM microvessels was evaluated, after applications of compound 48/80 or exogenous histamine, by computer‐assisted videodensitometric analyses. Real‐time confocal imaging enabled optical differentiation of first‐order pre‐ and postcapillaries from the capillary networks. Cytologic ultrastructure of the microvascular units was also evaluated. Results: Although endogenous histamine was measurable and its concentration was increased after application of compound 48/80, segmental endothelia of the CAM microvascular units consistently restricted extravasation of FITC‐dextran 150. Furthermore, intravascular injections of histamine also failed to induce interendothelial gap formation or macromolecular flux across the segmental CAM endothelia. Conclusions: These results are consistent with the interpretation that histamine‐activated transendothelial pathways are inactive in the CAM at day 6. Whether such inactivity serves to retard facilitation of CAM angiogenesis by activated mast cells remains to be tested.
Age‐Related Differences in Intestinal Arteriolar Responses to Venous Pressure Elevation in the Rat
Authors: Gosche John R. , Harris Patrick D. , Garrison R. Neal 
Published: April 2008

ABSTRACT Objective: We previously reported differences in intestinal arteriolar responses of adult and suckling rats to three stressors (hemorrhage, hypoxia, and hypothermia) that decreased intestinal blood flow. The small, premucosal arterioles of adult rats dilated in response to all three stressors, whereas the premucosal arterioles of suckling rats constricted or remained unchanged. One explanation for this difference might be absence of myogenic responsiveness in the premucosal arterioles of the immature rat. Methods: We used in vivo videomicroscopy to observe the intestinal arteriolar responses to venous pressure elevation (a myogenic stimulus) in adult (8‐ to 12‐week‐old) and suckling (8‐ to 12‐day‐old) Sprague‐Dawley rats. We increased portal venous pressure by 25 and 50% above the baseline pressure. Results: Arterioles in the adult rats displayed the expected “myogenic” response to venous pressure elevation (diameters decreased 12–19% when venous pressure was increased by 50%). In contrast to adult rats, arterioles in the suckling rats failed to constrict in response to increases in venous pressure (diameters increased 14–21% in response to a 50% increase in venous pressure). Conclusions: These results suggest diat the myogenic constrictor mechanisms for control of the microcirculation appear to be either nonfunctional or suppressed in the intestinal microcirculation of suckling rats.
Blood Flow in the Cerebral Capillary Network: A Review Emphasizing Observations with Intravital Microscopy
Authors: Hudetz Antal G. 
Published: April 2008

ABSTRACTCapillary perfusion in the brain is characterized by an essentially continuous flow of erythrocytes and plasma in almost all capillaries. Rapid fluctuations and spatial heterogeneity or red blood cell (RBC) velocity (0.5–1.8 mm/s) within the capillary network are present. In addition, low‐frequency (4–8 cpm) synchronous oscillations in RBC velocity in the capillary network emerge when perfusion to cerebral tissue is challenged. Despite the tortuous, three‐dimensional architecture of microvessels, functional intercapillary anastomoses are absent. At rest, red cells travel through the capillary network in 100–300 ms along 150‐ to 500‐μm‐long paths. Physiological challenges elicit sizable changes in RBC velocity with a minor role for capillary recruitment, change in capillary diameter, or flow shunting. During acute hypoxia, RBC velocity increases in all capillaries; the corresponding response to hypercapnia is more complex and involves redistribution of capillary flow toward more homogeneous perfusion. The response of capillary flow to decreased perfusion pressure reflects autoregulation of cerebral blood flow but also involves intranetwork redistribution of RBC flow between two populations of capillaries, postulated as thoroughfare channels and exchange capillaries. Flow reserve may be provided by the thoroughfare channels and may help maintain flow velocity and capillary exchange and protect the microcirculation from perfusion failure. Isovolemic hemodilution increases RBC velocity three‐ to fourfold and increases RBC flux to a moderate degree with a relatively small decrease in capillary hematocrit, under normal and compromised arterial blood supply. In cerebral ischemia, leukocyte adhesion is enhanced and appears reversible when the ischemia is moderate but may be progressive when the injury is severe. The observed flow behavior suggests the presence of a physiological regulatory mechanism of cerebral capillary flow that may involve communication among various microvascular and parenchymal cells and utilize locally acting endothelial and parenchymal mediators such as endothelium‐derived relaxing factor or nitric oxide.
Femoral Artery Ligation Stimulates Capillary Growth and Limits Training‐Induced Increases in Oxidative Capacity In Rats
Authors: Roberts Karl C. , Nixon Craig , Unthank Joseph L. , Lash Julia M. 
Published: April 2008

ABSTRACTObjective: The purpose of this study was to assess the interaction of arterial insufficiency and exercise training on soleus and plantaris muscle capillarity and oxidative capacity in adult rats.Methods: Arterial insufficiency was created by ligation (LIG) of the right femoral artery, and exercise training (TR) was performed on a rodent treadmill. The left hindlimb served as a normally (NORM) perfused control. Capillary:fiber ratio, number of capillary contacts per fiber, and citrate synthase activity (CS) were evaluated in the plantaris (Plant) and soleus (Sol) muscles.Results: In sedentary rats, CS was similar between LIG and NORM (Plant: 24.4 vs. 24.3 μmol · min−1 · g−1; Sol: 16.6 vs. 16.9 μmol · min−1 · g−1), but capillaries per fiber and capillary contacts per fiber were significantly elevated in the plantaris muscle of LIG (2.46 vs. 2.10 caps/fiber, 5.78 vs. 5.03 capillary contacts). CS was elevated in both limbs of TR but was lower in LIG than in NORM (Plant: 28.5 vs. 32.4 μmol · min−1; · g−1; Sol: 21.1 vs. 24.9 μmol · min−1 · g−1). Treadmill training did not significantly affect capillarity in NORM. However, muscles in the ligated limb of TR tended to have greater capillarity than comparable muscles in either NORM of TR of LIG in SED.Conclusions: These results demonstrate capillary proliferation in the plantaris but not soleus muscle of rat hindlimbs with femoral artery ligation. Capillarity and CS adaptations were not obligatorily related in LIG, and femoral artery ligation and exercise training appeared to have interactive effects on skeletal muscle capillarity.
Arteriolar Dilation Produced by Venule Endothelium‐Derived Nitric Oxide
Authors: Falcone Jeff C. , Meininger Gerald A. 
Published: April 2008

ABSTRACTObjective: We conducted bioassay experiments to determine whether nitric oxide produced by endothelial cells (endothelial‐derived nitric oxide, or EDNO) within large venules could act to dilate arterioles.Methods: In these experiments, parallel segments of first‐order arterioles and venules were isolated from skeletal muscle and were cannulated in series with a glass connecting tube (length: 300–500 μm). Arterioles were mechanically denuded of endothelium by a delicate yet abrasive rubbing technique. Venular endothelium remained intact. Endothelial denudation of arterioles was confirmed by the absence of dilation during exposure to acetylcholine (10−6 mol/L). The cannulated vessels were pressurized to 30 cm H2O and the arterioles preconstricted by approximately 50% with norepinephrine (10−10 mol/L).Results: Topical applications of acetylcholine (10−6 mol/L) or bradykinin (10−9 mol/L) during luminal perfusion from venule to arteriole produced significant arteriolar dilation. In contrast, a slight arteriolar constriction was observed when the direction of flow was reversed (i.e., arteriole to venule) in the presence of either acetylcholine (10−6 mol/L) or bradykinin (10−9 mol/L). Inhibition of venular EDNO with; NC‐monomethyl‐L‐arginine (L‐NMMA; 10−5 mol/L; 1 hour) completely abolished the arteriolar dilation observed in response to acetylcholine or bradykinin during venule to arteriole perfusion.Conclusions: These results demonstrate that venular‐derived EDNO can relax arteriolar vascular smooth muscle.
Regulation of E‐Selectin, P‐Selectin, and Intercellular Adhesion Molecule 1 Expression in Mouse Cremaster Muscle Vasculature
Authors: Jung Unsu , Ley Klaus 
Published: April 2008

ABSTRACTObjective: To investigate the expression of P‐ and E‐selectin and intercellular adhesion molecule 1 (ICAM‐1) in the vasculature of mouse cremaster muscles both with and without tumor necrosis factor a (TNF‐α) treatment.Methods: Mice received injections of monoclonal antibody to P‐selectin, E‐selectin, or ICAM‐1 before fixation to restrict detection to antigen expressed on the endothelial surface. Whole‐mount preparations of mouse cremaster muscles were fixed in acetone and stained using biotinylated secondary antibody and peroxidase‐conjugated streptavidin.Results: P‐selectin is expressed on the endothelial surface of cremaster muscle venules within 10 minutes after exteriorization. Expression increases upon treatment with TNF‐α (2 hours), reflecting transcriptional regulation of P‐selectin expression in situ. The baseline E‐selectin expression is patchy and barely detectable but shows a significant upregulation after treatment with TNF‐α. ICAM‐1 is constitutively expressed in unstimulated mouse cremaster venules and slightly upregulated after 2 hours of TNF‐α treatment. Under baseline conditions, neither E‐selectin, P‐selectin, nor ICAM‐1 is detectable in arterioles or capillaries. After TNF‐α treatment, arterioles stain faintly for P‐selectin, but not E‐selectin or ICAM‐1.Conclusion: The temporal and spatial pattern of expression of P‐ and E‐selectin and ICAM‐1 is consistent with the functional role of these molecules in mediating preferential leukocyte rolling and adhesion in mouse cremaster muscle venules.
Effects of Anastomoses on Solute Transcapillary Exchange in Countercurrent Systems
Authors: Wang W. , Michel C. C. 
Published: April 2008

ABSTRACTObjective: To investigate effects of anastomoses between the descending vasa recta (DVR) and the ascending vasa recta (AVR) on the distribution of small solutes in the interstitial fluid of the renal medulla.Methods: Countercurrent capillary loops, surrounded by a secretory epithelium, were used to model microvessels in the renal medulla. Anastomoses between the DVR and AVR were modeled as a decrease in cross‐sectional area of the vessels and a decrease in flow velocity from the base to the tip of the capillary loop. When experimental data were used to evaluate parameters of the model, it was seen that diffusive transport of solute in the axial direction of the capillary was negligible, and the equations could be greatly simplified.Results: General formulae of the solute concentration distribution were derived for different degrees of shunting between the two limbs of the capillary loop. Analytical solutions for the steady‐state solute distribution were obtained when the sizes of capillaries and flows in them were assumed to decrease linearly with the distance from the base to the tip of the capillary loop. When the effects of reduction in the size of the limbs were compared with the effects of reduction of flow velocities on solute distribution, it was found that, in the presence of anastomoses, change in flow velocity increases the axial gradient of the solute concentration more than change in the cross‐sectional area. The combined effects of a decrease in flow velocity and cross‐sectional area can easily double the axial gradient of the solute concentration for a modest degree of anastomotic shunting.Conclusions: In this study, we separated effects of anastomotic flow between the DVR and AVR from other factors affecting the complicated countercurrent solute exchanges in the renal medulla. Results from the model show that anastomoses increase the solute concentration in the medullary interstitium and also the axial gradient of the solute concentration there.