Tick saliva is a potent inhibitor of endothelial cell proliferation and angiogenesis

We report for the first time that saliva of the hard tick and Lyme disease vector, Ixodes scapularis, is a potent inhibitor of angiogenesis. Saliva (< or = 1:500 dilutions) or salivary gland (0.1-0.5 pairs/assay) dose-dependently inhibits microvascular endothelial cell (MVEC) proliferation. Inhibition was also detected with the saliva of the cattle tick Boophilus microplus but not with the salivary gland of Anopheles gambiae, An. stephensi, Lutzomyia longipalpis, Phlebotomus papatasi, Aedes aegypti, Culex quinquefasciatus, and Cimex lectularius. Inhibition of MVEC proliferation by I. Scapularis saliva was accompanied by a change in cell shape (shrinkage of the cytoplasm with loss of cell-cell interactions) and apoptosis which was estimated by expression of phosphatidylserine using the Apopercentage dye, and by a typical pattern of chromatin margination, condensation, and fragmentation as revealed by nuclear staining with Hoechst 33258. The effect of saliva appears to be mediated by endothelial cell alpha5beta1 integrin, because monoclonal antibodies against this but not alphavbeta3, alphavbeta5, alpha9beta1, or alpha2beta1 integrins remarkably block its effect. In addition, SDS/PAGE shows that saliva specifically degrades purified alpha5beta1 but not alphavbeta5 or alphavbeta3 integrins. Incubation of saliva with EDTA and 1,10-phenanthroline, but not phenylmethylsulfonyl fluoride (PMSF), inhibits saliva-dependent degradation of purified alpha5beta1 integrin, suggesting that a metalloprotease is responsible for the activity. Finally, saliva at < or = 1:1,000 dilutions blocks sprouting formation from chick embryo aorta implanted in Matrigel, an in vitro model of angiogenesis. These findings introduce the concept that tick saliva is a negative modulator of angiogenesis-dependent wound healing and tissue repair, therefore allowing ticks to feed for days. Inhibition of angiogenesis was hitherto an unidentified biologic property of the saliva of any blood-sucking arthropod studied so far. Its presence in tick saliva may be regarded as an additional source of angiogenesis inhibitors with potential applications for the study of both vector and vascular biology.     

Effects of imposed acid-base derangement on the cardiovascular effects and pharmacokinetics of bupivacaine and thiopental

BACKGROUND: By changing physicochemical properties such as effective lipophilicity, changes in blood pH could alter the distribution, elimination, and effects of weakly ionizing drugs. The authors examined the outcome of imposed acid-base derangement on cardiovascular effects and myocardial and whole body pharmacokinetics of bupivacaine, a weak base, and thiopental, a weak acid. METHODS: Intravenous infusions of rac-bupivacaine HCl (37.5 mg) or rac-thiopental sodium (250 mg, subanesthetic dose) were administered over 3 min to previously instrumented conscious ewes with normal blood pH, acidemia imposed by lactic acid infusion, or alkalemia imposed by bicarbonate infusion. Hemodynamic and electrocardiographic effects were recorded; arterial and coronary sinus drug blood concentrations were analyzed by chiral high-performance liquid chromatography. RESULTS: Bupivacaine decreased myocardial contractility, coronary perfusion, heart rate, and cardiac output; however, cardiac output and stroke volume were not as affected by bupivacaine with acidemia. Thiopental decreased myocardial contractility and stroke volume and increased heart rate; acidemia enhanced the tachycardia and produced a greater decrease in stroke volume than with alkalemia. Taken as a whole, the cardiovascular changes were not systematically modified by acid-base derangement. Overall, the tissue distribution of bupivacaine was favored by alkalemia, but thiopental pharmacokinetics were essentially unaffected by acid-base derangement. Acid-base derangement did not influence the kinetics of either drug enantioselectively. CONCLUSIONS: At the doses used, the hemodynamic and electrocardiographic effects of bupivacaine and thiopental were not systematically modified by acid-base derangement, nor were there changes in regional or whole body pharmacokinetics of either drug that were clearly related to acid-base status.     

Direct cardiac effects of coronary site-directed thiopental and its enantiomers: a comparison to propofol in conscious sheep

BACKGROUND: Previous evidence from laboratory animal studies indicates that R-thiopental has a greater margin of safety than either the more potent S-thiopental or the clinically used rac-thiopental. Although thiopental can cause cardiovascular depression from direct myocardial effects as well as indirect central nervous system and peripheral effects, no studies have yet determined whether its myocardial effects are enantioselective. A lesser direct effect would provide further evidence supporting R-thiopental as a preferred single enantiomer replacement for rac-thiopental. METHODS: The direct myocardial effects of the thiopental enantiomers were compared to those of rac-thiopental and propofol, using a crossover design with small incremental doses infused over 3 min, on separate days, into the left coronary arteries of conscious sheep. Hemodynamic and electrocardiographic measurements were acquired, and serial blood samples were collected during the studies for drug analyses. RESULTS: All three forms of thiopental and propofol produced significant hemodynamic effects consisting of dose-related and rapid-onset decreases in left ventricular dP/dtmax and stroke volume, and increases in left coronary blood flow and heart rate. Cardiac output, mean arterial blood pressure, and central venous pressure remained unaltered. The effects did not differ significantly among rac-thiopental, enantiopure R- or S-thiopental, or propofol. Arterial blood drug concentrations were consistently less than those associated with systemic effects. CONCLUSIONS: Although previous evidence indicates that R-thiopental could make a suitable single-enantiomer replacement for rac-thiopental, the current study did not find a significant difference in direct cardiac effects among the thiopental enantiomers, racemate, or propofol.     

Interactions between endothelin and nitric oxide in the regulation of vascular tone in obesity and diabetes

Endothelial dysfunction reflects an imbalance of vasodilators and vasoconstrictors. Endogenous endothelin activity seems to be increased in human obesity and type 2 diabetes, and cellular studies suggest that this factor may itself reduce bioavailable nitric oxide (NO). We studied 20 lean, 20 obese, and 14 type 2 diabetic individuals under three protocols, measuring leg vascular responses to intra-arterial infusions of NG-monomethyl-l-arginine (l-NMMA; an inhibitor of NO synthase) alone or in combination with BQ123 (an antagonist of type A endothelin receptors) or phentolamine (used as a control vasodilator). NO synthase inhibition alone (study 1) produced an approximately 40% increase in leg vascular resistance (LVR) in all three participant groups, which was not statistically different across groups (increase in LVR: lean, 135 +/- 28; obese, 140 +/- 32; type 2 diabetic, 184 +/- 51 units; NS). By design, BQ123 at the infused rate of 3 micromol/min produced equivalent approximately 35% reductions in LVR across groups. The subsequent addition of l-NMMA produced a greater increase in LVR among obese participants than lean or type 2 diabetic participants (study 2: lean, 182 +/- 48; obese, 311 +/- 66; type 2 diabetic, 186 +/- 40; P = 0.07). Compared with study 1, the effect of l-NMMA was magnified by BQ123 in obese participants but not in lean or type 2 diabetic participants (P = 0.005, study 1 vs. 2; P = 0.03 for group effect). Phentolamine (75 mg/min) produced vasodilation in obese participants comparable to that seen with BQ123 but failed to augment the L-NMMA response. Endothelin antagonism unmasks or augments NO synthesis capacity in obese but not type 2 diabetic participants. This suggests that impaired NO bioavailability as a result of endogenous endothelin may contribute to endothelial dysfunction in obesity, in addition to direct vasoconstrictor effects of endothelin. In contrast, endothelin antagonism alone is insufficient to restore impaired NO bioavailability in diabetes.     

Impact of fluid balance on incidence of atrial fibrillation after cardiothoracic surgery

Excessive fluid administration after cardiothoracic surgery has been proposed as a cause of postoperative atrial fibrillation. In this study, we observed that fluid balance and volume administered on postoperative day 2 was greater in patients who developed postoperative AF than in those who did not. We also found that net fluid balance on postoperative day 2 was an independent predictor of postoperative AF among patients not receiving prophylactic therapy.     

Development and preliminary validation of the Meta-cognitions Questionnaire-Adolescent Version

This study describes the development of the Meta-cognitions Questionnaire for Adolescents (MCQ-A). The adult version of this questionnaire has been widely used, and the meta-cognitive theory of emotional disorders has become influential in the adult literature. This study sought to examine the prevalence and emotional correlates of meta-cognition in adolescents. The MCQ-A was administered to 177 schoolchildren aged 13 through 17 years, together with measures of emotional well-being. Factor analysis suggested a five-factor solution similar to that reported for the adult version. Internal consistency of the scale was high. Scores ranged from low to high across the age range, suggesting that meta-cognitive beliefs are well-established by adolescence. Scores on the MCQ-A were highly correlated with a number of measures of emotional symptoms. The MCQ-A is a reliable and valid instrument for measuring meta-cognitive beliefs in adolescents. Young people aged between 13 and 17 years report a range of types and levels of meta-cognitive beliefs and these are positively associated with emotional symptoms.     

Combining depth cues: effects upon accuracy and speed of performance in a depth-ordering task

Two experiments investigated how the number of available depth cues affected the speed and accuracy of depth-ordering judgements. A series of textured tiles was presented on a computer monitor, with relative depths defined by combinations of contrast, blur and interposition. Subjects were required to move a mouse pointer inside each tile in turn, starting with the tile that appeared nearest, clicking on each. Accuracy of depth-ordering was much higher than chance in all conditions, though performance using the interposition cue alone was worse than in all other conditions. The only difference in reaction time in different cue conditions was in the time elapsed before the first-click. Subjects responded substantially faster when three depth cues were present (0.84 s) than when only one depth cue was present (1.41 s). The improvement in reaction time with cue numerosity is consistent with probability summation between cues extracted by independent processes.     

Emergency management program operational responses to weapons of mass destruction: Veterans Health Administration, 2001-2004

BACKGROUND: Despite the recognition of chemical emergencies, terrorist events, and ongoing threats, little practical guidance exists for healthcare facilities. METHODS: An approach and materials developed by the Veterans Health Administration in a five-element program over the last 2 years to enhance the existing emergency management program is outlined. Nine steps to the development of a comprehensive all-hazards, emergency plan and program, with auditing and improvement tools are offered. RESULTS: Cognitive aids for clinical use are available on-line and in hard copy. A hazard assessment modeled patients as emission sources documenting the operations strategies under which level C personal protective equipment will protect healthcare workers. The development of this response program appears to support a broader, long-standing VHA approach to problem solving. This involves bringing together individual talented field staff, representing specific skills, geographic regions, and work styles; investing in face-to-face consensus development; and developing programs with extensive internal peer-review ("field-based," "bottom-up and top-down," and external reviews). CONCLUSIONS: Comprehensive and effective programs can be constructed at low cost with reasonable speed within large systems with a public mandate, leading to responsible use of public funds internally, and as models for private sector programs. It is the long-term operational cost implications, under budget constraints in health care, which often present the true challenge.     

The inhibition of calcium signaling in T lymphocytes from old mice results from enhanced activation of the mitochondrial permeability transition pore

Aging attenuates calcium signaling in T lymphocytes from old mice. Aging also attenuates the sustained elevation of cell free calcium by ionomycin, which is similar to the T cell receptor signal. In T lymphocytes from young mice, the ionomycin-induced elevation of cell free calcium was inhibited by collapsing the mitochondrial membrane potential by uncouplers and ionophores, and activation of the permeability transition. In T lymphocytes from old mice, the mitochondrial membrane potential was largely collapsed, but cyclosporin and N-methyl-val-4-cyclosporin, inhibitors of the permeability transition, restored the mitochondrial potential, as well as the ionomycin-induced elevation of cell free calcium. In addition, the generation of reactive oxygen species in the presence of mitochondrial electron transport inhibitors was relatively enhanced in T lymphocytes from old mice. The association between low rhodamine 123 fluorescence and attenuated calcium signaling in T lymphocytes from old mice is also shown to be a consequence of the collapsed mitochondrial potential. These results suggest that Ca2+ signaling is attenuated in T lymphocytes from old mice because of an enhanced activation of the permeability transition.