Pierre Theodore

STIM1 calcium sensor is required for activation of the phagocyte oxidase during inflammation and host defense

The stromal-interacting molecule 1 (STIM1) is a potent sensor of intracellular calcium, which in turn regulates entry of external calcium through plasma membrane channels to affect immune cell activation. Although the contribution of STIM1 to calcium signaling in lymphocytes has been well studied, the role of this protein in neutrophil-mediated inflammation and host defense is unknown. We report that STIM1-deficient murine neutrophils show loss of store-operated calcium entry (SOCE) in response to both soluble ligands that activate G-proteins as well as Fcγ-receptor or integrin ligation that activates tyrosine kinase signaling. This results in modest defects in phagocytosis and degranulation responses but a profound block in superoxide production by the phagocyte oxidase. We trace the primary intracellular target of calcium to be protein kinase C isoforms α and β (PKCα and PKCβ), which in turn phosphorylate subunits of the oxidase leading to superoxide production. In vivo the loss of SOCE in stim1(-/-) chimeric mice results in marked susceptibility to bacterial infections but also protection from tissue injury in hepatic ischemia/reperfusion injury. These results demonstrate the critical role of STIM1-mediated SOCE and define major protein targets of calcium signaling in neutrophil activation during inflammatory disease.

Circulatory support for fulminant myocarditis: consideration for implantation, weaning and explantation

OBJECTIVE Fulminant myocarditis (FM) is an uncommon but life-threatening condition for which a mechanical circulatory support (MCS) device can be life-saving. However, device selection, weaning and explantation procedures remain poorly defined. METHODS Four patients were bridged to recovery using the Thoratec biventricular support device. All four were in a state of cardiogenic shock with rapid deterioration of their clinical status despite increasing doses of inotropes. Three patients required mechanical respiratory support, three were anuric and one was dialyzed. Echocardiography showed a mean ejection fraction of 12+/-8%. RESULTS Each Thoratec implantation was performed on cardiopulmonary bypass with a beating heart. Three patients underwent biventricular cannulation. The fourth patient underwent left ventricular and right atrial cannulation. All patients manifested evidence of moderate to severe end organ dysfunction after device implantation. However, by explantation, end organ function had recovered in all patients. After a mean duration of 17+/-10 days, all the patients showed evidence of myocardial recovery. Recovery was confirmed on echocardiography which showed opening of the aortic valve and contraction of both ventricles. The weaning process was performed in 2-5 days by setting the device in a fixed mode and increasing the rate. Device explantation was uneventful in the four patients. At the 6 months echocardiography follow-up, all had normal systolic function. CONCLUSION In patients with FM, biventricular support allows full circulatory support and unloads both ventricles until recovery occurs. In this set of patients, weaning and removal procedures are straight-forward. These results suggest an aggressive stance toward implantation of MCS in patients with FM.

A safe and reproducible anastomotic technique for minimally invasive Ivor Lewis oesophagectomy: the circular-stapled anastomosis with the trans-oral anvil,

OBJECTIVES In expert hands, the intrathoracic oesophago-gastric anastamosis usually provides a low rate of strictures and leaks. However, anastomoses can be technically challenging and time consuming when minimally invasive techniques are used. We present our preliminary results of a standardised 25 mm/4.8mm circular-stapled anastomosis using a trans-orally placed anvil. MATERIALS AND METHODS We evaluated a prospective cohort of 37 consecutive patients offered minimally invasive Ivor Lewis oesophagectomy at a tertiary referral centre. The oesophago-gastric anastomosis was created using a 25-mm anvil (Orvil, Autosuture, Norwalk, CT, USA) passed trans-orally, in a tilted position, and connected to a 90-cm long polyvinyl chloride delivery tube through an opening in the oesophageal stump. The anastomosis was completed by joining the anvil to a circular stapler (end-to-end anastomosis stapler (EEA XL) 25 mm with 4.8-mm staples, Autosuture, Norwalk, CT, USA) inserted into the gastric conduit. Primary outcomes were leak and stricture rates. RESULTS Thirty-seven patients (mean age 65 years) with distal oesophageal adenocarcinoma (n=29), squamous cell cancer (n=5) or high-grade dysplasia in Barretts oesophagus (n=3) underwent an Ivor Lewis oesophagectomy between October 2007 and August 2009. The abdominal portion was operated laparoscopically in 30 patients (81.1%). The thoracic portion was done using a muscle-sparing mini-thoracotomy in 23 patients (62.2%) and thoracoscopic techniques in 14 patients (37.8%). There were no intra-operative technical failures of the anastomosis or deaths. Five patients had strictures (13.5%) and all were successfully treated with endoscopic dilations. One patient had an anastomotic leak (2.7%) that was successfully treated by re-operation and endoscopic stenting of the anastomosis. DISCUSSION The circular-stapled anastomosis with the trans-oral anvil allows for an efficient, safe and reproducible anastomosis. This straightforward technique is particularly suited to the completely minimally invasive Ivor Lewis oesophagectomy.

Human–porcine receptor–ligand compatibility within the immune system: relevance for xenotransplantation

Immune responses to xenografts are likely to be highly dependent on the efficiency of molecular interactions between the donor and the recipient species. This brief review summarizes what is currently known about the compatibilities across the human–porcine species barrier of the molecular interactions that are important in the immune response.

Esophageal erosion 9 years after anterior cervical plate implantation

BACKGROUND Anterior cervical discectomy and fusion is 1 of the most common spinal procedures performed. Most complications are observed during the intraoperative or immediate postoperative period. Long-term complications are not often described. A review of literature revealed 5 years as the longest complication interval. We present a case of esophageal erosion 9 years after initial surgery that was successfully treated. CASE DESCRIPTION We describe a case of a 42-year-old woman who presented with recurrent pneumonia secondary to esophageal erosion almost 1 decade after anterior cervical spine surgery. This is the longest documented delay in presentation of esophageal erosion published to date. The diagnosis was made during EGD and the treatment consisted of plate removal and esophagus repair. The pertinent literature is reviewed and the therapeutic implications are discussed. CONCLUSIONS In this report, we describe an uncommon case of esophageal erosion 9 years after anterior cervical plating. In cases of hardware migration even many years after surgery or in patients with intrinsic esophageal disease, potential esophageal damage should be considered.

Function of porcine adhesion molecules in a human marrow microenvironment

BACKGROUND One way to circumvent the need for chronic immunosuppression in solid organ xenografting may be to induce donor-specific tolerance using bone marrow transplantation. If this approach is to succeed in the pig-to-human species combination, pig marrow must be capable of maturing into relevant tolerance-inducing cells and replenishing itself in host human marrow. One possible barrier is adhesion molecule incompatibility. We have studied the compatibility across the pig-human species barrier of two well-characterized ligands known to be important in hematopoiesis, CD44 and very late antigen (VLA)-4. METHODS In vitro long-term bone marrow cultures were studied in which the effects of blocking antibodies were assessed by measuring cell numbers and colony-forming units. RESULTS The blocking of CD44 had a comparable inhibitory effect on the hematopoiesis of human and pig marrow, even if the latter was maintained on a human stromal layer. Both cellular proliferation and colony-forming activity were inhibited by anti-CD44 monoclonal antibody. By contrast, a significant difference was observed in VLA-4 usage by hematopoietic cells of the two species. Blocking VLA-4 markedly inhibited human hematopoietic cellular proliferation but had no effect on pig hematopoiesis, on either porcine or human stroma. CONCLUSIONS The data suggest that the incompatibility of either CD44 or VLA-4 is unlikely to limit the efficiency of porcine hematopoiesis in a human marrow environment. However, the difference in VLA-4 utilization between these species raises the possibility that other interactions may be important for effective porcine hematopoiesis and that their failure to function between species may contribute to the poor function of porcine hematopoietic cells in primate marrow microenvironments.

Emergent Management of Malignancy-Related Acute Airway Obstruction

Acute obstruction of the airway in the emergent situation results from a wide variety of malignant and benign disease processes. Acute management involves establishing a secure and patent route for adequate gas exchange. This requires rapid determination of the location of the obstruction and nature of the obstruction followed by a thoughtful management approach based on findings. Difficult anatomy, hemorrhage, dense secretions, inflammation, and bulky tumor mass can significantly complicate the task of clearing the airway. Obstruction of the central airways by malignant tumor is associated with poor prognosis, but quality of life is considerably improved by restoration of adequate central airways. For both the patient and the clinician, the presentation can be frightening, and advanced interventional pulmonary/endobronchial techniques are required to achieve prompt relief of symptoms. The alleviation of central airway obstruction by tumor is most often palliative, with improvement of quality of life the primary goal rather than cure. This review will cover covers an approach to the patient with airway obstruction that results from malignancy involving the trachea or proximal bronchial tree and affecting gas exchange.

Cross-species compatibility of intercellular adhesion molecule-1 (CD54) with its ligands.

BACKGROUND The molecular interactions of intercellular adhesion molecule-1 (ICAM-1; CD54) are potentially important in several situations in the context of pig-to-human xenotransplantation. If porcine bone marrow is to be used for the induction of xenograft tolerance in humans, the role that has been suggested for ICAM-1 in the interactions of haematopoietic stem cells makes its cross-species compatibility important. Similarly, the potential role of ICAM-1 interactions in graft rejection makes it an important molecule to study. METHODS An in vitro static cell-to-cell adhesion study was used to look at the successful interaction of ICAM-1 with its ligands across the pig-human species barrier in both directions. A second in vitro system, the standard long-term bone marrow culture (LT-BMC), was used to study the functional role of ICAM-1 in haematopoiesis. RESULTS Human ICAM-1 was able to adhere to ligands on porcine cells, including one or more ligand that contains CD18. Conversely, human CD18-containing ligands mediated adherence to porcine cells. Using the long-term bone marrow culture system, there was no evidence that blocking the interactions of ICAM-1 inhibited hematopoiesis, either in the human-human or pig-human combinations of precursor cells and marrow stroma. CONCLUSIONS ICAM-1 is able to interact with at least some of its ligands across the species barrier, in both pig-human and human-pig combinations. However, the interactions of ICAM-1 do not appear to be central to hematopoiesis, at least in the model system used.

Development and analysis of transgenic mice expressing porcine hematopoietic cytokines: a model for achieving durable porcine hematopoietic chimerism across an extensive xenogeneic barrier

Abstract: The capacity of mixed hematopoietic chimerism to induce tolerance has not been demonstrated in discordant xenogeneic species combinations because of the difficulty in achieving lasting hematopoietic engraftment. In an effort to create a model of long‐lasting disparate xenogeneic hematopoietic chimerism, we have developed transgenic (Tg) mice carrying porcine cytokines. Three lines of Tg mice were generated: one carrying porcine IL‐3 and GM‐CSF genes only (termed IL/GM) and the remaining two lines carrying in addition, the soluble SCF gene (termed IL/GM/sS) or membrane‐bound SCF gene (termed IL/GM/mS). Sera from mice with IL/GM and IL/GM/sS transgenes markedly stimulated the proliferation of swine marrow cells in vitro. However, proliferation of swine marrow cells was not induced in cultures containing IL/GM/mS sera. Consistent with these observations, ELISA assays revealed detectable levels of porcine cytokines in the sera of IL/GM and IL/GM/sS, but not in sera of IL/GM/mS Tg mice. Marrow stromal cells prepared from all three kinds of Tg mice, but not those from non‐Tg littermates, were capable of supporting the growth of porcine hematopoietic cells in vitro. Immunodeficient Tg mice were generated by crossing Tg founders with C.B‐17 SCID mice for five generations. All Tg immunodeficient mice showed improved porcine hematopoietic engraftment compared with non‐Tg controls. These Tg mice provide a useful model system for studying porcine hematopoietic stem cells, and for evaluating the feasibility of donor‐specific tolerance induction by mixed chimerism across highly disparate xenogeneic barriers.

Rasamsonia argillacea Pulmonary and Aortic Graft Infection in an Immune-Competent Patient

ABSTRACT Rasamsonia argillacea (formerly known as Geosmithia argillacea) is a fungus recently recognized as a pathogen of immunocompromised patients. Here we report the first case of Rasamsonia infection in an immunocompetent host, presenting as a pulmonary and aortic graft infection. Its morphological similarity to nonpathogenic Penicillium species delayed the diagnosis and initiation of appropriate treatment.