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We previously reported that in the adult animal extinction in pairs resulted in enhanced extinction, showing that social presence can reduce previously acquired fear responses. Based on our findings that juvenile and adult animals differ in the mechanisms of extinction, here we address whether the social presence of a conspecific affects extinction in juvenile animals similarly to adults. We further address whether such presence has a different impact on juvenile males and females. To that end, we examined in our established experimental setting whether conditioned male and female animals extinguish contextual fear memory better while in pairs. Taking advantage of the role of oxytocin (OT) in the mediation of extinction memory and social interaction, we also study the effect of antagonizing the OT receptors (OTR) either systemically or in the prefrontal cortex on social interaction-induced effects of fear extinction. The results show that social presence accelerates extinction in males and females as compared to the single condition. Yet, we show differential and opposing effects of an OTR antagonist in both sexes. Whereas in females, the systemic application of an OTR antagonist is associated with impaired extinction, it is associated with enhanced extinction in males. In contrast, prefrontal OT is not engaged in extinction in juvenile males, while is it is critical in females. Previously reported differences in the levels of prefrontal OT between males and females might explain the differences in OT action. These results suggest that even during the juvenile period, critical mechanisms are differently involved in the regulation of fear in males and females.

Introduction: Primary lymphoma of the colon is exceedingly rare and comprises 0.2-1% of all colon tumors. The most common subtype of lymphoma in the colon is non-Hodgkin lymphoma. Symptoms are often nonspecific, and treatment varies between chemotherapy alone and a combination of surgery and chemotherapy., Case Presentation: We describe a case of a Ashkenazi Jew patient who presented in the typical way that carcinoma of the colon might present but turned out to have a very rare type of tumor in both its histology and its location., Conclusion: There was apparent discordance between the relative bulkiness and gross appearance of the tumor with the unrevealing result of the biopsies, demanding a high level of suspicion as to the actual presence and possible type of such a tumor in the future.

Accumulating evidence suggests that the cyclooxygenase-2 (COX-2) enzyme has additional catalytic-independent functions. Here we show that COX-2 appears to be cleaved in mouse and human tumors, which led us to hypothesize that COX-2 proteolysis may play a role in cell proliferation. The data presented herein show that a K598R point mutation at the carboxyl-terminus of COX-2 causes the appearance of several COX-2 immunoreactive fragments in nuclear compartments, and significantly enhances cell proliferation. In contrast, insertion of additional mutations at the border of the membrane-binding and catalytic domains of K598R COX-2 blocks fragment formation and prevents the increase in proliferation. Transcriptomic analyses show that K598R COX-2 significantly affects the expression of genes involved in RNA metabolism, and subsequent proteomics suggest that it is associated with proteins that regulate mRNA processing. We observe a similar increase in proliferation by expressing just that catalytic domain of COX-2 (ΔNT- COX-2), which is completely devoid of catalytic activity in the absence of its other domains. Moreover, we show that the ΔNT- COX-2 protein also interacts in the nucleus with β-catenin, a central regulator of gene transcription. Together these data suggest that the cleavage products of COX-2 can affect cell proliferation by mechanisms that are independent of prostaglandin synthesis., Competing Interests: The authors declare no conflict of interest

Background: The effect of 1-3 months of preoperative exclusive total parental nutrition (TPN) in active Crohn's disease (CD) patients is not well established. We investigated the efficacy of exclusive TPN in active CD patients., Methods: In a retrospective multi-visit study with data according to our standard care therapy, we assessed clinical and laboratory remission to refractory CD with exclusive preoperative TPN. Inclusion required exclusive preoperative home TPN without additional oral intake for 1-3 months prior to planning surgery., Results: Twenty preoperative CD patients (65% male; 35% female) were on exclusive TPN. The mean age of the cohort was 30.8 ± 11.6 years. Mean duration of preoperative TPN treatment was 73 days (range: 24-142 days). Most patients had terminal ileal (35%) or ileocolonic CD (30%), and with stricturing (B2) phenotype. All 20 patients had significant clinical improvement in all disease activity indices at the end of preoperative TPN (baseline vs. post TPN): HBI 14.5 vs. 4.0 ( p = 0.001); BMI 19.2 vs. 19.7 kg/m 2 ( p = 0.017); CRP 57.2 vs. 10.3 mg/L ( p = 0.001); Fecal calprotectin (FC) 672 vs. 200 (μg/g); albumin 2.7 vs. 3.6 g/dL ( p = 0.001). Two patients (10%) no longer required surgery after completion of exclusive TPN., Conclusion: Exclusive preoperative TPN was found to provide significant improvement in nutritional status, and clinical and laboratory remission in severe active Crohn's patients.

The limbic circuit is still undergoing maturation during juvenility and adolescence, explaining why environmental and metabolic challenges during these developmental periods can have specific adverse effects on cognitive functions. We have previously shown that long-term exposure (8-12 weeks) to high-fat diet (HFD) during adolescence (from weaning to adulthood), but not at adulthood, was associated with altered amygdala and hippocampal functions. Moreover, these HFD effects were normalized by treatment with glucocorticoid receptor (GR) antagonists. Here, we examined in male rats whether acute exposure (7-9 days) to HFD during juvenility [from postnatal day (PND) 21 to PND 28-30] or adulthood (from PND 60 to PND 67-69) is sufficient to affect hippocampal functions and whether it is also dependent on GRs activation. Juvenile HFD abolished both hippocampal synaptic plasticity, assessed through in vivo long-term potentiation (LTP) in CA1, and long-term hippocampal-dependent memory, using object location memory (OLM). No effect of HFD was observed in short-term OLM suggesting a specific effect on consolidation process. In contrast, adult HFD enhanced in vivo LTP and OLM. Systemic application of GR antagonist alleviated HFD-induced LTP and OLM impairments in juveniles. These results suggest that acute exposure to HFD during juvenility is sufficient to impair hippocampal functions in a GR-dependent manner. Interestingly, this effect depends on the developmental period studied as acute exposure to HFD at adulthood did not impair, but rather enhanced, hippocampal functions.

Juvenility represents a critical developmental phase during which exposure to a high fat diet (HFD) can severely modify cognitive and emotional functioning. The purpose of this study was to address how short and acute exposure to a HFD during juvenility affects social memory recognition and prefrontal long-term potentiation (LTP). As LTP and social memory depend on the neuromodulator oxytocin (OXY) and due to its role in metabolism, we also examined the effects of OXY in mediating HFD-induced alterations in social memory and LTP. Our results show that short exposure to a HFD during juvenility impairs social preference memory and prefrontal LTP. Interestingly, whereas systemic injections of OXY reversed the impairments in HFD-fed animals and impaired LTP and memory in control animals; prefrontal injections of the OXY agonist TGOT reversed the effects in HFD animals without affecting control animals. Exposure to HFD was associated with a reduction in the levels of OXY in the prefrontal compared to control animals. Interestingly, the restoration of social memory by TGOT in HFD animals was also associated with normalization of OXY in the prefrontal. These results point to a role that prefrontal OXY has in mediating the effects of HFD on memory and plasticity., (© The Author(s) 2018. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.)

Laser tissue soldering is a method of repairing incisions. It involves the application of a biological solder to the approximated edges of the incision and heating it with a laser beam. A pilot clinical study was carried out on 10 patients who underwent laparoscopic cholecystectomy. Of the four abdominal incisions in each patient, two were sutured and two were laser soldered. Cicatrization, esthetical appearance, degree of pain, and pruritus in the incisions were examined on postoperative days 1, 7, and 30. The soldered wounds were watertight and healed well, with no discharge from these wounds or infection. The total closure time was equal in both methods, but the net soldering time was much shorter than suturing. There was no difference between the two types of wound closure with respect to the pain and pruritus on a follow-up of one month. Esthetically, the soldered incisions were estimated as good as the sutured ones. The present study confirmed that temperature-controlled laser soldering of human skin incisions is clinically feasible, and the results obtained were at least equivalent to those of standard suturing.

Most cases of blunt hepatic trauma are treated nowadays non-operatively. This type of conservative treatment has resulted in increased complication rate. Delayed complications occur in cases that didn't require surgical intervention during the first 24 hours. The most common late complication is hemorrhage. We report a case of two weeks delayed hemorrhage after blunt hepatic trauma in an adult. We describe the diagnostic procedures, the surgical treatment and review the relevant literature.

Atherosclerosis remains a major cause of death in the developed world despite the success of therapies that lower cholesterol and BP. The intermediate-conductance calcium-activated potassium channel KCa3.1 is expressed in multiple cell types implicated in atherogenesis, and pharmacological blockade of this channel inhibits VSMC and lymphocyte activation in rats and mice. We found that coronary vessels from patients with coronary artery disease expressed elevated levels of KCa3.1. In Apoe(-/-) mice, a genetic model of atherosclerosis, KCa3.1 expression was elevated in the VSMCs, macrophages, and T lymphocytes that infiltrated atherosclerotic lesions. Selective pharmacological blockade and gene silencing of KCa3.1 suppressed proliferation, migration, and oxidative stress of human VSMCs. Furthermore, VSMC proliferation and macrophage activation were reduced in KCa3.1(-/-) mice. In vivo therapy with 2 KCa3.1 blockers, TRAM-34 and clotrimazole, significantly reduced the development of atherosclerosis in aortas of Apoe(-/-) mice by suppressing VSMC proliferation and migration into plaques, decreasing infiltration of plaques by macrophages and T lymphocytes, and reducing oxidative stress. Therapeutic concentrations of TRAM-34 in mice caused no discernible toxicity after repeated dosing and did not compromise the immune response to influenza virus. These data suggest that KCa3.1 blockers represent a promising therapeutic strategy for atherosclerosis.

The creation of anastomoses between various parts of the GI tract is a major task in the daily practice of oncological, reconstructive and transplant surgery. The most widely used anastomosing techniques today involve the use of sutures or metal titanium staples. Both techniques involve foreign material penetrating the tissue and evoking localized inflammatory response, tissue injury and breaking of mucosal barriers that may facilitate bacterial growth within the anastomotic line, increasing the propensity to anastomotic-related morbidity. Different types of compression devices were successfully used clinically in the past. The history and evolving characteristics of this technology is reviewed. Nitinol-based solutions for the creation of compression anastomosis are evaluated as a possible potential for revolutionary impact on the current surgical methods and anastomosing technology in the alimentary tract and beyond.

Flow-induced dilation (FID) is an important physiological stimulus that regulates tissue blood flow and is mediated by endothelium-derived factors that play a role in vascular integrity and the development of atherosclerosis. In coronary artery disease (CAD), conduit artery FID is impaired. The purpose of this study was to determine the mechanism of FID in human visceral adipose and examine whether the presence of conduit coronary atherosclerosis is associated with altered endothelial function in visceral fat. FID was determined in isolated visceral fat arterioles from patients with and without CAD. After constriction with endothelin-1, increases in flow produced an endothelium-dependent vasodilation that was sensitive to N(omega)-nitro-l-arginine methyl ester (l-NAME) in visceral fat arterioles from patients without CAD. In contrast, l-NAME alone or in combination with indomethacin had no effect on FID in similarly located arterioles from patients with CAD. Flow increased dichlorofluorescein (DCF) and dihydroethidium fluorescence accumulation in arterioles from patients with CAD versus without, indicative of the production of oxidative metabolites and superoxide, respectively. Both the dilation and DCF fluorescence to flow were reduced in the presence of the H(2)O(2) scavenger polyethylene glycol-catalase. Exogenous H(2)O(2) elicited similar relaxations of arterioles from patients in both groups. These data indicate that FID in visceral fat arterioles is nitric oxide dependent in the absence of known CAD. However, in the presence of CAD, H(2)O(2) replaces nitric oxide as the mediator of endothelium-dependent FID. This study provides evidence that adverse microvascular changes during CAD are evident in human visceral adipose, a tissue associated with CAD.

Acute lung injury (ALI) carries a high mortality in critically ill patients. Recent reports correlate elevated concentrations of endothelium-derived microparticles (EMPs) with diseases of endothelial dysfunction. Many of these diseases have ALI sequelae. We hypothesize that EMPs contribute to endothelial cell (EC) dysfunction and development of ALI. To test this hypothesis, we treated isolated vessels with EMPs and examined changes in vasodilation. Endothelial cell cultures were incubated with EMPs and examined for changes in stimulated nitric oxide (*NO) production and nitric oxide synthase (eNOS) activation. Finally, EMPs were injected into rats and mice and lungs examined for ALI. In both mouse and human ex vivo vessel preparations, we found a marked attenuation of endothelium-mediated vasodilation after EMP treatment (4 x 10(6)/mL). This dysfunction was not corrected by pretreatment of EMPs with free radical scavengers. Coincubation of EMPs with EC cultures yielded a three-fold reduction in A23187-stimulated *NO release. Western analysis of these cells showed a corresponding decrease in eNOS phosphorylation at Ser1179 and a decrease in hsp90 association. Measurements of lung permeability, myeloperoxidase activity, and histology of EMPs-treated Brown Norway rats demonstrated pulmonary edema, neutrophil recruitment, and compromise of the endothelial-alveolar barrier as a second hit phenomenon. In C57BL/6 mice, exogenous EMPs caused a significant rise in pulmonary capillary permeability both as a primary and secondary injury. These findings demonstrate EMPs are capable of inducing significant lung injury at pathophysiologically relevant concentrations. Endothelium-derived microparticles inhibit endothelium-mediated vasodilation and *NO generation from eNOS. Once elucidated, EMP mechanisms of inducing ALI and endothelial dysfunction may present new therapeutic targets.

Objective: Endothelial dysfunction and vascular dysregulation contribute to the pathological effects of radiation on tissues. The objectives of this study were to assess the acute effect of irradiation on acetylcholine (Ach)-induced dilation of gut submucosal microvessels., Methods and Results: Rats were exposed in vivo to 1 to 9 cGy in 3 fractions per week on alternate days for 3 successive weeks for a total dose of up to 2250 cGy. Submucosal microvessels were isolated after varying levels of irradiation. Diameters of isolated vessels were measured using videomicroscopy, and the dose-response relationship to Ach was determined. Dihydroethidine and 2', 7'-dichlorodihydrofluorescein diacetate fluorescent probes were used to assess reactive oxygen species (ROS) production. After constriction (30% to 50%) with endothelin, dilation to graded doses of Ach (10(-9)-10(-4) M) was observed in control vessels (maximal dilation [MD] 87+/-3%; n=7). However, Ach-induced dilation was reduced in vessels from irradiated rats (MD=3+/-9%; n=7; P= or <0.05 versus controls). Significant increases in superoxide and peroxides were observed in irradiated microvessels. Irradiated microvessels pretreated with superoxide dismutase-mimetic demonstrated significant improvement in Ach-induced vasodilation compared with irradiation alone, suggesting that superoxide contributes to impaired dilation to Ach after irradiation., Conclusions: Radiation induces acute microvascular dysfunction in the resistance arterioles of the intestine. Enhanced ROS contribute to this dysfunction and therefore may represent a novel therapeutic target to minimize radiation toxicity in the gut.

Epoxyeicosatrienoic acids (EETs) are metabolized by soluble epoxide hydrolase (sEH) to form dihydroxyeicosatrienoic acids (DHETs) and are putative endothelium-derived hyperpolarizing factors (EDHFs). EDHFs modulate microvascular tone; however, the chemical identity of EDHF in the human coronary microcirculation is not known. We examined the capacity of EETs, DHETs, and sEH inhibition to affect vasomotor tone in isolated human coronary arterioles (HCAs). HCAs from right atrial appendages were prepared for videomicroscopy and immunohistochemistry. In vessels preconstricted with endothelin-1, three EET regioisomers (8,9-, 11,12-, and 14,15-EET) each induced a concentration-dependent dilation that was sensitive to blockade of large-conductance Ca2+-activated K+ (BK(Ca)) channels by iberiotoxin. EET-induced dilation was not altered by endothelial denudation. 8,9-, 11,12-, and 14,15-DHET also dilated HCA via activation of BK(Ca) channels. Dilation was less with 8,9- and 14,15-DHET but was similar with 11,12-DHET, compared with the corresponding EETs. Immunohistochemistry revealed prominent expression of cytochrome P-450 (CYP450) 2C8, 2C9, and 2J2, enzymes that may produce EETs, as well as sEH, in HCA. Inhibition of sEH by 1-cyclohexyl-3-dodecylurea (CDU) enhanced dilation caused by 14,15-EET but reduced dilation observed with 11,12-EET. DHET production from exogenous EETs was reduced in vessels pretreated with CDU compared with control, as measured by liquid chromatography electrospray-ionization mass spectrometry. In conclusion, EETs and DHETs dilate HCA by activating BK(Ca) channels, supporting a role for EETs/DHETs as EDHFs in the human heart. CYP450s and sEH may be endogenous sources of these compounds, and sEH inhibition has the potential to alter myocardial perfusion, depending on which EETs are produced endogenously.

Objective: Endothelium-dependent dilation to acetylcholine (Ach) is reduced in mucosal arterioles from patients with inflammatory bowel disease (IBD). The contributions of both nitric oxide (NO) and endothelial-derived hyperpolarizing factor (EDHF) are decreased. We hypothesized that the remaining dilation results from products of cyclooxygenase., Methods and Results: High-performance liquid chromatography (HPLC) was used to isolate eicosanoid vasodilator products and videomicroscopy was used to examine vasomotor responses in human mucosal arterioles from subjects with or without IBD undergoing bowel resection surgeries. In subjects without IBD, Ach constricted (-52%+/-10%) arterioles devoid of endothelium. Indomethacin (INDO) (cyclooxygenase inhibitor) had no effect. In contrast, Ach dose-dependently dilated both intact and endothelial denuded arterioles from patients with IBD. The dilation was converted to constriction by INDO (-54%+/-9%; P<0.05 versus non-IBD) or by BWA868C (PGD2 receptor antagonist). Only in arterioles from subjects with IBD did Ach produce an arachidonic acid metabolite that comigrated on HPLC with PG D2 (PGD2). Exogenous PGD2 dilated (max=66%+/-4%) IBD arterioles., Conclusions: In arterioles from IBD patients, Ach-mediated dilation shifts from endothelial production of NO and EDHF to nonendothelial generation of a PG, likely PGD2. This is a novel dilator mechanism arising from nonendothelial vascular tissue that compensates for loss of endothelium-dependent dilation. PGD2 appears to be important in regulating mucosal blood flow in patients with IBD, implicating potentially detrimental effects from nonsteroidal antiinflammatory drugs.

Adenosine is a key myocardial metabolite that elicits coronary vasodilation in a variety of pathophysiological conditions. We examined the mechanism of adenosine-induced vasodilation in coronary arterioles from patients with heart disease. Human coronary arterioles (HCAs) were dissected from pieces of the atrial appendage obtained at the time of cardiac surgery and cannulated for the measurement of internal diameter with videomicroscopy. Adenosine-induced vasodilation was not inhibited by endothelial denudation, but A(2) receptor antagonism with 3,7-dimethyl-1-propargylxanthine and adenylate cyclase (AC) inhibition with SQ22536 significantly attenuated the dilation. In contrast, A(1) receptor antagonism with 8-cyclopentyl-1,3-dipropylxanthine significantly augmented the sensitivity to adenosine. Moreover, dilation to A(2a) receptor activation with 2-p-(2-carboxyethyl)phenethylamino-5'-N-ethylcarboxamido-adenosine hydrochloride was reduced by the A(1) receptor agonist (2S)-N(6)-(2-endo-norbornyl)adenosine. The nonspecific calcium-activated potassium (K(Ca)) channel blocker tetrabutylammonium attenuated adenosine-induced dilation, as did the intermediate-conductance K(Ca) blocker clotrimazole. Neither the large-conductance K(Ca) blocker iberiotoxin nor small-conductance K(Ca) blocker apamin altered the dilation. In conclusion, adenosine endothelium independently dilates HCAs from patients with heart disease through a receptor-mediated mechanism that involves the activation of intermediate-conductance K(Ca) channels via an AC signaling pathway. The roles of A(1) and A(2) receptor subtypes are opposing, with the former being inhibitory to AC-mediated dilator actions of the latter. These observations identify unique fundamental physiological characteristics of the human coronary circulation and may help to target the use of novel adenosine analogs for vasodilation in perfusion imaging or suggest new strategies for myocardial preconditioning.

The endothelium plays an important role in maintaining vascular homeostasis by synthesizing and releasing several mediators of vasodilation, which include prostacyclin (PGI(2)), nitric oxide, and endothelium-derived hyperpolarizing factor (EDHF). We have recently defined the role of nitric oxide and PGI(2) in the dilation of submucosal intestinal arterioles from patients with normal bowel function. However, significant endothelium-dependent dilator capacity to ACh remained after inhibiting both these mediators. The current study was designed to examine the potential role of EDHF in human intestinal submucosal arterioles. ACh elicited endothelium-dependent relaxation in the presence of inhibitors of nitric oxide synthase and cyclooxygenase (23 +/- 10%, n = 6). This ACh-induced relaxation was inhibited and converted to constriction by catalase (-53 +/- 10%, n = 6) or KCl (-30 +/- 3%, n = 7), whereas 17-octadecynoic acid and 6-(2-propargylloxyphenyl) hexanoic acid, two inhibitors of cytochrome P450 monooxygenase, had no significant effect (3 +/- 1% and 20 +/- 8%, n = 5, respectively). Exogenous H(2)O(2) elicited dose-dependent relaxation of intact microvessels (52 +/- 10%, n = 7) but caused frank vasoconstriction in arterioles denuded of endothelium (-73 +/- 8%, n = 7). ACh markedly increased the dichlorofluorescein fluorescence in intact arterioles in the presence of nitric oxide synthase and cyclooxygenase inhibitors compared with control and compared with catalase-treated microvessels (363.6 +/- 49, 218.8 +/- 10.6, 221.9 +/- 27.9, respectively, P < 0.05 ANOVA, n = 5 arbitrary units). No changes in the dichlorofluorescein fluorescence were recorded in vessels treated with ACh alone. These results indicate that endothelial production of H(2)O(2) occurs in response to ACh in human gut mucosal arterioles but that H(2)O(2) is not an EDHF in this tissue. Rather, we speculate that it stimulates the release of a chemically distinct EDHF.

Background & Aims: Inflammatory bowel disease (IBD; i.e., Crohn's disease, ulcerative colitis) is characterized by refractory inflammatory ulceration and damage to the intestine. Mechanisms underlying impaired healing are not defined. Because microvascular dysfunction resulting in diminished vasodilatory capacity and tissue hypoperfusion is associated with impaired wound healing, we hypothesized that microvascular dysfunction may also occur in chronic IBD., Methods: Intact submucosal arterioles from control, involved, and uninvolved IBD specimens were assessed using in vitro videomicroscopy to assess endothelium-dependent vasodilation in response to acetylcholine (Ach) and fluorescence microscopy to detect oxyradicals., Results: Normal microvessels dilated in a dose-dependent and endothelium-dependent manner to Ach (maximum, 82% +/- 2%; n = 34). Inhibition of nitric oxide synthase with N(G)-nitro-L-arginine methyl ester (L-NAME) reduced maximal dilation to 54% +/- 6% (P < 0.05, n = 7), and further reduction was observed after inhibiting cyclooxygenase (indomethacin; 23% +/- 10%, n = 6). Chronically inflamed IBD microvessels showed significantly reduced Ach-induced vasodilation (maximum, 15% +/- 2%; n = 33), with no effect of L-NAME. Indomethacin eliminated the remaining Ach-induced vasodilation, resulting in frank vasoconstriction (-54% +/- 9%, n = 6). Uninvolved IBD gut vessels and non-IBD inflammatory controls responded in a fashion similar to normal vessels. IBD-involved microvessels generated significantly higher levels of reactive oxygen species compared with control and uninvolved IBD vessels (P < 0.01)., Conclusions: Human intestinal microvessels from chronically inflamed IBD show microvascular endothelial dysfunction, characterized by loss of NO-dependent dilation that may contribute to reduced perfusion, poor wound healing, and maintenance of chronic inflammation.

Background: Hypercholesterolemia and sickle cell disease (SCD) impair endothelium-dependent vasodilation by dissimilar mechanisms. Hypercholesterolemia impairs vasodilation by a low-density lipoprotein (LDL)-dependent mechanism. SCD has been characterized as a chronic state of inflammation in which xanthine oxidase (XO) from ischemic tissues increases vascular superoxide anion (O2*-) generation. Recent reports indicate that apolipoprotein (apo) A-1 mimetics inhibit atherosclerosis in LDL receptor-null (Ldlr-/-) mice fed Western diets. Here we hypothesize that L-4F, an apoA-1 mimetic, preserves vasodilation in hypercholesterolemia and SCD by decreasing mechanisms that increase O2*- generation., Methods and Results: Arterioles were isolated from hypercholesterolemic Ldlr-/- mice and from SCD mice that were treated with either saline or L-4F (1 mg/kg per day). Vasodilation in response to acetylcholine was determined by videomicroscopy. Effects of L-4F on LDL-induced increases in endothelium-dependent O2*- generation were determined on arterial segments via the hydroethidine assay and on stimulated endothelial cell cultures via superoxide dismutase-inhibitable ferricytochrome c reduction. Effects of L-4F on XO bound to pulmonary arterioles and content in livers of SCD mice were determined by immunofluorescence. Hypercholesterolemia impaired vasodilation in Ldlr-/- mice, which L-4F dramatically improved. L-4F inhibited LDL-induced increases in O2*- in arterial segments and in stimulated cultures. SCD impaired vasodilation, increased XO bound to pulmonary endothelium, and decreased liver XO content. L-4F dramatically improved vasodilation, decreased XO bound to pulmonary endothelium, and increased liver XO content compared with levels in untreated SCD mice., Conclusions: These data show that L-4F protects endothelium-dependent vasodilation in hypercholesterolemia and SCD. Our findings suggest that L-4F restores vascular endothelial function in diverse models of disease and may be applicable to treating a variety of vascular diseases.

Thrombin (Thromb), activated as part of the clotting cascade, dilates conduit arteries through an endothelial pertussis toxin (PTX)-sensitive G-protein receptor and releases nitric oxide (NO). Thromb also acts on downstream microvessels. Therefore, we examined whether Thromb dilates human coronary arterioles (HCA). HCA from right atrial appendages were constricted by 30-50% with endothelin-1. Dilation to Thromb (10(-4)-1 U/ml) was assessed before and after inhibitors with videomicroscopy. There was no tachyphylaxis to Thromb dilation (maximum dilation = 87.0%, ED(50) = 1.49 x 10(-2)). Dilation to Thromb was abolished with either hirudin or denudation but was not affected by PTX. Neither N(omega)-nitro-l-arginine methyl ester (n = 7), indomethacin (n = 9), (1)H-[1,2,4] oxadiazolo-[4,3-a]quinoxalin-1-one (n = 6), tetraethylammonium chloride (n = 5), nor iberiotoxin (n = 4) reduced dilation to Thromb. However, KCl (maximum dilation = 89 +/- 5 vs. 20 +/- 10%; P < 0.05; n = 7), tetrabutylammonium chloride (maximum dilation = 79 +/- 7 vs. 21 +/- 4%; P < 0.05; n = 5), and charybdotoxin (maximum dilation = 89 +/- 4 vs. 10 +/- 2%; P < 0.05; n = 4) attenuated dilation to Thromb. In contrast to animal models, Thromb-induced dilation in human arterioles is independent of G(i)-protein activation and NO release. However, Thromb dilation is endothelium dependent, is maintained on consecutive applications, and involves activation of K(+) channels. We speculate that an endothelium-derived hyperpolarizing factor contributes to Thromb-induced dilation in HCA.

We have previously observed that bolus fluid resuscitation in uncontrolled hemorrhagic shock induced by solid organ injury leads to increased blood loss and mortality. In the present investigation, we studied the effect of continuous fluid resuscitation on the hemodynamic response and survival following massive splenic injury (MSI) in rats. The animals were randomized into 11 groups: group 1, sham-operated; group 2, MSI untreated; group 3, MSI treated with 17.5 mL/kg/h of Ringers lactate (RL) solution (RL-17.5); group 4, MSI treated with 35 mL/kg/h RL (RL-35); group 5, MSI treated with 70 mL/kg/h RL (RL-70); group 6, MSI treated with 7.5 mL/kg/h of 7.5% NaCl (HTS-7.5); group 7, MSI treated with 15 mL/kg/h of 7.5% NaCl (HTS-15); group S, MSI treated with 30 mL/kg/h of 7.5% NaCl (HTS-30); group 9, MSI treated with 7.5 mL/kg/h 6% hydroxyethyl starch (HES-7.5); group 10, MSI treated with 15 mL/kg/h 6% hydroxyethyl starch (HES-15); and group 11, MSI treated with 30 mL/kg/h 6% hydroxyethyl starch (HES-30). MSI in untreated group 2 was followed by a fall of mean arterial pressure (MAP) to 50.1 +/- 6.7 mmHg (P < 0.001) in 15 min. Mean survival time (MST) was 99.5 +/- 16.6 min, and total blood loss (TBL) was 37.8% +/- 2.6% of blood volume. Fluid treatment with increasing volumes of RL in groups 3, 4, and 5 was followed by a gradual increase in TBL compared with untreated animals, and MST remained unchanged. Increasing volumes of HTS infusion in groups 6, 7, and 8 was also followed by incease in TBL, but MST remained unchanged except for an increase to 123.0 +/- 20.5 min (P < 0.05) in group 6. Increasing volumes of HES in groups 9, 10, and 11 was also followed by increase in TBL, but MST remained unchanged. In conclusion, continuous infusion of LR, HTS, and HES following massive splenic injury resulted in a significant increase in intra-abdominal bleeding, but survival time in the first hour following injury remained unchanged in contrast to bolus fluid infusion, which increases early mortality.