Local nervous mechanism in regulation of blood flow in human subcutaneous tissue

The effect of local venous stasis upon blood flow in human subcutaneous adipose tissue on the distal part of the forearm was investigated in three healthy subjects and two chronically sympathectomized patients suffering from manual hyperhidrosis. The area under study was separated into two parts by means of a lead shield exerting a pressure of about 360 mmHg on the skin. The effect of venous stasis of about 40 mmHg on one side of the shield upon blood flow measured simultaneously on both sides of the shield by the local 133Xenon washout technique was investigated. During venous stasis on one side of the shield, blood flow decreased about 40% on both sides. The vasoconstrictor impulse could be transmitted over a distance of about 1-2 cm. The phenomenon was unaffected by nerve blockade induced 3 cm proximally, medially, and laterally to the area by infiltration the skin with lidocaine. Thus a vasoconstrictor impulse could be transmitted from the side of stasis to the non stasis side of the lead shield. The transmission was not affected by phentolamine but was blocked by lidocaine and chronic sympathetic denervation. The vasoconstrictor impulse elicited during venous stasis is therefore most likely transmitted by means of a local nervous mechanism involving sympathetic adrenergic vasoconstrictor fibres.     

Supraceliac, but not infrarenal, aortic cross-clamping upregulates neutrophil integrin CD11b

OBJECTIVE: To evaluate the effects of supraceliac and infrarenal aortic cross-clamping on the expression of neutrophil integrin in CD11b (a marker of systemic cytokine release). DESIGN: Two groups, determined by anatomic placement of aortic cross-clamp. Laboratory personnel were blinded as to group assignment. SETTING: University teaching and community hospitals. Laboratory facilities used were university and Veteran's Affairs medical centers. PARTICIPANTS: Patients scheduled for aortic surgery. INTERVENTIONS: Blood sampling was performed at baseline, after 30 minutes of aortic cross-clamp duration, 30 and 90 minutes after reperfusion (for tumor necrosis factor-alpha plasma levels in infrarenal cross-clamp group), and at baseline and 90 minutes reperfusion (for neutrophil CD11b expression quantification) in both groups. MEASUREMENTS AND MAIN RESULTS: Tumor necrosis factor-alpha measured by ELISA technique did not change at any time period in the infrarenal clamping group. Neutrophil CD11b expression, measured by double antibody staining and FACScan analysis, did not change significantly at 90 minutes of reperfusion in the infrarenal group, but increased significantly (p < 0.05) in the supraceliac aortic cross-clamp group. CONCLUSION: Neutrophil integrin CD11b has been demonstrated to be the primary adhesive glycoprotein responsible for neutrophil organ entrapment and subsequent neutrophil-mediated reperfusion injury. These results suggest that upregulation of neutrophil integrin CD11b after supraceliac aortic clamping may in part be responsible for the higher incidence of acute lung injury after thoracic aortic aneurysm repair requiring supraceliac clamping when compared with infrarenal aneurysm surgery.     

Rat blood neutrophils express very late antigen 4 and it mediates migration to arthritic joint and dermal inflammation

Blood neutrophils contribute to joint injury in human and experimental models of arthritis. Neutrophil migration out of the blood in joint inflammation involves both the CD18 (beta2) integrins and a CD18 integrin-independent pathway. To investigate this migration, radiolabeled rat blood neutrophils were used to measure neutrophil accumulation in the inflamed joints of rats with adjuvant arthritis and the role of leukocyte integrins in migration to these joints and to dermal inflammation was determined. Neutrophils migrated rapidly (<2 h) to the inflamed joints 14-18 d after immunization with adjuvant. Blocking monoclonal antibodies (mAbs) to both LFA-1 and Mac-1 together, as well as a mAb to CD18, inhibited neutrophil accumulation in the inflamed joints by 50-75%. However, migration to dermal inflammation induced by C5a(des Arg)' tumor necrosis factor alpha, lipopolysaccharide, and poly-inosine:cytosine was inhibited by approximately 90%. Flow cytometry revealed the expression of low levels of very late antigen 4 (VLA-4) on nearly all rat blood neutrophils. Treatment with anti-VLA-4 plus anti-LFA-1 but neither mAb alone, strongly (60-75%) inhibited neutrophil accumulation in arthritic joints. This mAb combination also inhibited neutrophil migration to dermal inflammatory reactions by 30-70%. Blocking VLA-4 together with the CD18 integrins inhibited neutrophil accumulation by 95-99%, virtually abolishing neutrophil accumulation in cutaneous inflammation. A similar blockade of VLA-4 and CD18 decreased neutrophil accumulation in the inflamed joints by 70-83%, but a significant portion of the neutrophil accumulation to these joints still remained. In conclusion, rat blood neutrophils express functional VLA-4 that can mediate neutrophil migration to both inflamed joints and dermal inflammatory sites. VLA-4 appears to be able to substitute for LFA-1 in this migration and is particularly important for accumulation in inflamed joints. However, there exists an additional CD18- and VLA-4-independent pathway of neutrophil migration to arthritic joints that is not involved in acute dermal inflammation.     

Optical amplification of ligand-receptor binding using liquid crystals

Liquid crystals (LCs) were used to amplify and transduce receptor-mediated binding of proteins at surfaces into optical outputs. Spontaneously organized surfaces were designed so that protein molecules, upon binding to ligands hosted on these surfaces, triggered changes in the orientations of 1- to 20-micrometer-thick films of supported LCs, thus corresponding to a reorientation of approximately 10(5) to 10(6) mesogens per protein. Binding-induced changes in the intensity of light transmitted through the LC were easily seen with the naked eye and could be further amplified by using surfaces designed so that protein-ligand recognition causes twisted nematic LCs to untwist. This approach to the detection of ligand-receptor binding does not require labeling of the analyte, does not require the use of electroanalytical apparatus, provides a spatial resolution of micrometers, and is sufficiently simple that it may find use in biochemical assays and imaging of spatially resolved chemical libraries.     

Laminin directs growth cone navigation via two temporally and functionally distinct calcium signals

During development, growth cones navigate to their targets via numerous interactions with molecular guidance cues, yet the mechanisms of how growth cones translate guidance information into navigational decisions are poorly understood. We have examined the role of intracellular Ca2+ in laminin (LN)-mediated growth cone navigation in vitro, using chick dorsal root ganglion neurons. Subsequent to contacting LN-coated beads with filopodia, growth cones displayed a series of stereotypic changes in behavior, including turning toward LN-coated beads and a phase of increased rates of outgrowth after a pause at LN-coated beads. A pharmacological approach indicated that LN-mediated growth cone turning required an influx of extracellular Ca2+, likely in filopodia with LN contact, and activation of calmodulin (CaM). Surprisingly, fluorescent Ca2+ imaging revealed no LN-induced rise in intracellular Ca2+ in filopodia attached to their parent growth cone. However, isolation of filopodia by laser-assisted transection unmasked a rapid, LN-specific rise in intracellular Ca2+ (+73 +/- 11 nM). Additionally, a second, sustained rise in intracellular Ca2+ (+62 +/- 8 nM) occurred in growth cones, with a distinct delay 28 +/- 3 min after growth cone filopodia contacted LN-coated beads. This delayed, sustained Ca2+ signal paralleled the phase of increased rates of outgrowth, and both events were sensitive to the inhibition of Ca2+/CaM-dependent protein kinase II (CaM-kinase II) with 2 microM KN-62. We propose that LN-mediated growth cone guidance can be attributed, in part, to two temporally and functionally distinct Ca2+ signals linked by a signaling cascade composed of CaM and CaM-kinase II.     

Paradoxical hypertension after reversal of heart failure in patients treated with intensive vasodilator therapy

Hypertension is a major cause of heart failure, evolving from left ventricular hypertrophy to systolic and diastolic dysfunction. Although effective heart failure therapy has been associated with a lowering or no change in systemic arterial blood pressure in long-term follow-up, this study describes the symptomatic, clinical, and left ventricular functional response of a subgroup of heart failure patients with a prior history of hypertension who demonstrated a paradoxical hypertensive response despite high-dose vasodilator therapy. We prospectively identified 45 patients with a past history of hypertension who had become normotensive with symptomatic heart failure. Of these 45 heart failure patients, 12 became hypertensive while receiving therapy in follow-up, with systolic blood pressure > or = 140 mm Hg (Group A). The remaining 33 patients did not have a hypertensive response to therapy (Group B). In the 12 Group A patients, 60+/-10 years old, with symptomatic heart failure for 6.3+/-4.3 years, vasodilator therapy was intensified in the 2.0+/-0.5 years of follow-up, achieving final doses of enalapril 78+/-19 mg and isosorbide dinitrate 293 +/-106 mg per day. New York Heart Association classification improved from 2.9+/-0.8 to 1.3+/-0.5 (P < or = .0001), with a reduction in heart-failure-related hospitalizations. Left ventricular ejection fraction increased from 17+/-6% to 40+/-10% (P < .0001). Follow-up blood pressure at 1 to 3 months was unchanged. However, both systolic and diastolic blood pressure increased at final follow-up, rising from 116+/-14 to 154+/-13 mm Hg (P = .0001) and from 71+/-9 to 85+/-14 mm Hg (P = .004), respectively. Renal function remained unchanged. Although both groups had similar clinical responses, there were more blacks and women in the hypertensive Group A. Effectively, 12 of 45 (27%) heart failure patients with an antecedent history of hypertension demonstrated a paradoxical hypertensive response to vasodilator therapy. The recurrence of hypertension in a significant portion of patients successfully treated for heart failure has important clinical implications.     

The ATP synthase of Trypanosoma brucei is developmentally regulated by an inhibitor peptide

The Trypanosoma brucei ATP synthase, like those of other organisms, is composed of two moieties, the membrane bound F0 and the catalytic F1 with each of these parts comprised of multiple subunits. In addition, an endogenous inhibitor peptide of the ATP synthase has been identified from a variety of sources. Previous reports have suggested that the Trypanosoma brucei ATPase may not possess such an inhibitor. Recently, we have isolated an inhibitor peptide fraction from the procyclic form of Trypanosoma brucei by modification of a previously published procedure. This fraction is composed of two dominant polypeptides with estimated molecular weights of 14,000 and 12,000 and an additional polypeptide of 15,000 that may or may not be functionally required. Antibodies raised to the smallest polypeptide showed strong cross reactivity with the other two polypeptides, suggesting that they are related. Antibodies to rat liver inhibitor peptide show cross reactivity with the same polypeptides in crude fractions. The inhibitor peptide fraction strongly suppresses the ATPase activity of membrane bound ATPase in a Mg(2+)-dependent manner and is cold and heat stable. Using antibodies to the smallest polypeptide and rat liver inhibitor peptide we have shown in crude extracts from the three experimental life cycle stages of T. brucei that the inhibitor peptide(s) is developmentally regulated to a modest extent. The pattern of regulation is opposite of the pattern seen for the ATP synthase complex. This suggests that the ATP synthase is stringently controlled in T. brucei in a unique way.