Bradykinin-activated contractile signalling pathways in human myometrial cells are differentially regulated by arrestin proteins.

Bradykinin is associated with infections and inflammation, which given the strong correlation between uterine infection and preterm labour may imply that it could play a role in this process. Therefore, we investigated bradykinin signalling, and the roles that arrestin proteins play in their regulation in human myometrial cells. Bradykinin induced rapid, transient intracellular Ca(2+) increases that were inhibited following B2 receptor (B2R) antagonism. Arrestin2 or arrestin3 depletion enhanced and prolonged bradykinin-stimulated Ca(2+) responses, and attenuated B2R desensitisation. Knockdown of either arrestin enhanced B2R-stimulated ERK1/2 signals. Moreover, depletion of either arrestin elevated peak-phase p38-MAPK signalling, yet only arrestin3 depletion prolonged B2R-induced p38-MAPK signals. Arrestin2-knockdown augmented bradykinin-induced cell movement. Bradykinin stimulates pro-contractile signalling mechanisms in human myometrial cells and arrestin proteins play key roles in their regulation. Our data suggest bradykinin not only acts as an utertonin, but may also have the potential to enhance the contractile environment of the uterus.

Distinct and overlapping functional roles of Src family kinases in mouse platelets.

BACKGROUND AND OBJECTIVES: Src family kinases (SFKs) play a critical role in initiating and propagating signals in platelets. The aims of this study were to quantitate SFK members present in platelets and to analyze their contribution to platelet regulation using glycoprotein VI (GPVI) and intregrin αIIbß3, and in vivo. METHODS AND RESULTS: Mouse platelets express four SFKs, Fgr, Fyn, Lyn and Src, with Lyn expressed at a considerably higher level than the others. Using mutant mouse models, we demonstrate that platelet activation by collagen-related peptide (CRP) is delayed and then potentiated in the absence of Lyn, but only marginally reduced in the absence of Fyn or Fgr, and unaltered in the absence of Src. Compound deletions of Lyn/Src or Fyn/Lyn, but not of Fyn/Src or Fgr/Lyn, exhibit a greater delay in activation relative to Lyn-deficient platelets. Fibrinogen-adherent platelets show reduced spreading in the absence of Src, potentiation in the absence of Lyn, but no change in the absence of Fyn or Fgr. In mice double-deficient in Lyn/Src or Fgr/Lyn, the inhibitory role of Lyn on spreading on fibrinogen is lost. Lyn is the major SFK-mediating platelet aggregation on collagen at arterial shear and its absence leads to a reduction in thrombus size in a laser injury model. CONCLUSION: These results demonstrate that SFKs share individual and overlapping roles in regulating platelet activation, with Lyn having a dual role in regulating GPVI signaling and an inhibitory role downstream of αIIbß3, which requires prior signaling through Src.

Src family kinases are essential for primary aggregation by G(i) -coupled receptors.

INTRODUCTION AND BACKGROUND: Adrenaline stimulates biphasic aggregation in plasma through the G(i) -coupled α(2A) -adrenoreceptor. In the present study, we demonstrate that both primary and secondary wave aggregation induced by adrenaline in plasma is blocked by two structurally distinct inhibitors of Src family kinases, dasatinib and PD0173952. METHODS AND RESULTS: In contrast, primary aggregation is partially inhibited or unaffected in the presence of inhibitors of cyclo-oxygenase, phosphoinositide (PI) 3-kinases, and P2Y(1) and P2Y(12) ADP receptors, although secondary aggregation is abolished. The ability of adrenaline to inhibit adenylyl cyclase and to synergize with platelet agonists in mediating platelet activation in plasma is retained in the presence of Src family kinase inhibition. Moreover, adrenaline does not activate Src family kinases, as determined by western blotting of their regulatory tyrosines, suggesting that constitutive signaling from Src family kinases may underlie their role in activation. Adrenaline is widely used in clinical laboratories for investigation of patients with suspected bleeding disorders. In a group of 90 unrelated patients with a clinically diagnosed platelet bleeding disorder, we identified four who did not exhibit primary wave aggregation in response to adrenaline, although the catecholamine potentiated the response to other agonists, and five who failed to undergo secondary wave aggregation. In contrast, adrenaline stimulated biphasic aggregation in 60 controls. All of the patients with a defective response to adrenaline had impaired ADP-induced platelet activation. CONCLUSIONS: The present results indicate a previously unappreciated role for Src family kinases in mediating G(i) signaling in plasma, and demonstrate heterogeneity in response to adrenaline in patients with a clinically diagnosed platelet disorder.

Ensuring the accuracy of digital sphygmomanometers for home use.

OBJECTIVE: To describe the techniques for assessing the accuracy of digital sphygmomanometers. DESIGN: The necessary equipment and the recommended procedures for determining the accuracy of digital units by comparison with a mercury sphygmomanometer were reviewed. RESULTS: Evaluation of the accuracy of digital sphygmomanometers is a simple two-phase process: (1) comparison of the pressure sensors against a mercury column and (2) assessment of the ability to detect Korotkoff sounds. The only equipment needed is a mercury column, a Y tubing, a "dummy" arm, two male-female adapters, and a stethoscope. The two short ends of the Y tubing are used to connect the mercury sphygmomanometer and the digital unit, and the long end of the Y tubing is attached to the cuff of the digital unit. The inflation mechanism of the digital unit (manual or automatic) influences the approach used for comparing the two units. For both manually and automatically inflatable digital units, the digital display should be within +/- 4 mm Hg of the mercury level; likewise, a properly functioning digital unit should detect Korotkoff sounds (both systolic and diastolic readings) within +/- 4 mm Hg of the auscultated blood pressure measurements. If the digital sphygmomanometer is judged to be accurate, 6-month reevaluations are suggested. CONCLUSION: With use of minimal equipment, digital sphygmomanometers (except the new finger blood pressure monitors) can easily be assessed for accuracy by comparing the pressure sensors against a mercury unit and testing the sensitivity for detecting Korotkoff sounds. Self-monitoring of the blood pressure is helpful in assessing blood pressure changes over time and in evaluating antihypertensive therapy.

Squamous cell carcinoma in southern and northern Australia.

Squamous cell carcinoma (scc) of the skin was studied in two similar populations, one living in the temperate zone of Australia, the other living in the tropics. In the tropics, the patients were significantly younger, the man to woman ratio approached unity, and women had significantly more sccs on the legs. In the temperate zone, men had significantly more on the head and neck, but women had significantly more on the upper and lower limbs.

Hypertension: role of the nurse-therapist.

In this article, we describe the evolution of the hypertension nurse-therapist program at the Mayo Clinic. Because of the large numbers of patients in whom hypertension is a major risk factor for cardiovascular disease, a leading cause of death in the United States and other industrialized nations, an approach was devised in which, with physician supervision, specially trained nurses managed many aspects of the acute and long-term outpatient care of hypertensive patients. Clinical trials in which nonphysician care-providers were used to treat hypertensive patients and to maintain long-term blood pressure control provided an opportunity to identify and to expand the concept of continuing care for blood pressure management in a community hypertension clinic. Currently, almost 7,000 patient visits are scheduled annually in this program, and these patients are seen by five full-time hypertension nurse-therapists.