The effects of propranolol and clonidine on bone marrow expression of hematopoietic cytokines following trauma and chronic stress.

Background: Attenuating post-injury neuroendocrine stress abrogates persistent injury-associated anemia. Our objective was to examine the mechanisms by which propranolol and clonidine modulate this process. We hypothesized that propranolol and clonidine would decrease bone marrow expression of high-mobility group box-1 (HMGB1) and increase expression of stem cell factor (SCF) and B-cell lymphoma-extra large (Bcl-xL).

Clonidine restores vascular endothelial growth factor expression and improves tissue repair following severe trauma.

Background: We hypothesized that clonidine and propranolol would increase VEGF and VEGF-receptor expression and promote lung healing following severe trauma and chronic stress.

Methods: Sprague-Dawley rats were subjected to lung contusion (LC), lung contusion/hemorrhagic shock (LCHS), or lung contusion/hemorrhagic shock/daily restraint stress (LCHS/CS). Clonidine and propranolol were administered daily.

Persistent injury-associated anemia: the role of the bone marrow microenvironment.

Background: The regulation of erythropoiesis involves hematopoietic progenitor cells, bone marrow stroma, and the microenvironment. Following severe injury, a hypercatecholamine state develops that is associated with increased mobilization of hematopoietic progenitor cells to peripheral blood and decreased growth of bone marrow erythroid progenitor cells that manifests clinically as a persistent injury-associated anemia. Changes within the bone marrow microenvironment influence the development of erythroid progenitor cells.

Effects of trauma, hemorrhagic shock, and chronic stress on lung vascular endothelial growth factor.

Background: Vascular endothelial growth factor (VEGF) and its receptors (VEGFR-1 and VEGFR-2) regulate vascular permeability and endothelial cell survival. We hypothesized that hemorrhagic shock (HS) and chronic stress (CS) would increase expression of lung VEGF and its receptors, potentiating pulmonary edema in lung tissue.

Materials And Methods: Male Sprague-Dawley rats aged 8-9 wk were randomized: naïve control, lung contusion (LC), LC followed by HS (LCHS), and LCHS with CS in a restraint cylinder for 2 h/d (LCHS/CS).

Severe trauma and chronic stress activates extramedullary erythropoiesis.

Background: Severe traumatic injury is associated with bone marrow dysfunction that manifests as impaired erythropoiesis and prolonged hematopoietic progenitor cell (HPC) mobilization from the bone marrow. Extramedullary erythropoiesis, the development of red blood cells outside the bone marrow, has not been studied after severe injury and critical illness. This study examined the influence of lung contusion/hemorrhagic shock (LCHS) followed by chronic stress (CS) on the rodent spleen and to investigate the involvement of the splenic erythropoietin (EPO)/EPO receptor and BMP4 signaling.

Daily propranolol administration reduces persistent injury-associated anemia after severe trauma and chronic stress.

Background: After severe trauma, patients develop a norepinephrine-mediated persistent, injury-associated anemia. This anemia is associated with suppression of bone marrow (BM) erythroid colony growth, along with decreased iron levels, and elevated erythropoietin (EPO) levels, which are insufficient to promote effective erythropoiesis. The impact of norepinephrine on iron regulators, such as ferroportin, transferrin, and transferrin receptor-1 (TFR-1), is unknown.

Clonidine reduces norepinephrine and improves bone marrow function in a rodent model of lung contusion, hemorrhagic shock, and chronic stress.

Background: Propranolol has been shown previously to restore bone marrow function and improve anemia after lung contusion/hemorrhagic shock. We hypothesized that daily clonidine administration would inhibit central sympathetic outflow and restore bone marrow function in our rodent model of lung contusion/hemorrhagic shock with chronic stress.

Methods: Male Sprague-Dawley rats underwent 6 days of restraint stress after lung contusion/hemorrhagic shock during which the animals received clonidine (75 μg/kg) after the restraint stress.

Characterization of erythropoietin and hepcidin in the regulation of persistent injury-associated anemia.

Background: The cause of persistent injury-associated anemia is multifactorial and includes acute blood loss, an altered erythropoietin (EPO) response, dysregulation of iron homeostasis, and impaired erythropoiesis in the setting of chronic inflammation/stress. Hepcidin plays a key role in iron homeostasis and is regulated by anemia and inflammation. Erythropoietin is a main regulator of erythropoiesis induced by hypoxia.

Accuracy of intra-articular glenohumeral injections: the anterosuperior technique with arthroscopic documentation.

Purpose: Our objective was to assess the accuracy rate of needle placement with the anterosuperior technique of glenohumeral joint injection that uses familiar palpable superficial landmarks as a guide instead of diagnostic imaging.

Methods: Between April 2007 and October 2007 at our institution, 42 patients met the study inclusion criteria of being aged 18 years or older and undergoing shoulder arthroscopy. For the injection (performed by 1 surgeon), anesthetized patients were placed in the beach-chair position with the arm in adduction and internal rotation.