Differentiation state and responses to hematopoietic growth factors of murine myeloid cells transformed by myb

Murine hematopoietic cells can be transformed in vitro by recombinant retroviruses that express the myb oncogene, and hematopoietic growth factor (HGF)-dependent myeloid cell lines can be derived from these transformed primary cells. In this study, the differentiation state and responses of myb-transformed hematopoietic cells (MTHCs) have been investigated. We find that MTHCs exhibit properties of early myeloid progenitors including synergistic responses to combinations of HGFs and expression of certain surface markers. As reported previously, MTHCs respond well to granulocyte-macrophage colony-stimulating factor (GM- CSF) but can also respond to interleukin-3 (IL-3); the response to the latter factor depends on the mouse strain from which the cells are derived. Although these single factors stimulate MTHCs, combinations of these factors with colony-stimulating factor-1 (CSF-1 or M-CSF) or Steel factor (SLF or SCF) act synergistically to promote colony formation. The surface markers expressed by MTHCs include both granulocyte-macrophage lineage specific antigens Gr-1, 7/4, F4/80, and Mac-1, as well as two antigens found on early progenitors and stem cells--Thy-1 and Sca-1 (Ly6E). Expression of the latter markers is often heterogeneous and can be modulated by the growth factors to which the cells are exposed. Finally, we show that monocytic differentiation of MTHCs can be induced by exposure to tumor necrosis factor (TNF alpha). Taken together, these results suggest that MTHCs will be a useful model for studying HGF/cytokine responses in both proliferation and differentiation.     

The prevalence and risk factors for atrioesophageal fistula after percutaneous radiofrequency catheter ablation for atrial fibrillation: the Canadian experience

Purpose

Atrioesophageal fistula (AEF) is an infrequent complication of radiofrequency (RF) ablation for atrial fibrillation (AF). The aim of this study was to determine the prevalence and operator-dependent factors associated with AEF using a nationwide survey of electrophysiologists (EP).

Methods

Thirty-eight EPs performing AF ablation between 2008 and 2012 were invited to complete a web-based questionnaire assessing the prevalence and factors associated with AEF.

Results

Responses were obtained from 25 EPs (68 %) accounting for 7,016 AF ablations. Five cases of proven AEF (0.07 %) were reported. Operators who reported AEF [AEF (+)] more often used general anesthesia (GA) [90 % AEF (+) vs. 44 % AEF (?), p?=?0.046]. AEF (+) operators were also more likely to be users of the non-brushing technique in the posterior wall of the LA [5 (100 %) AEF (+) vs. 5 (25 %) AEF (?), p?=?0.005]. The combined usage of GA and non-brushing technique during LA posterior wall ablation had a strong association with AEF (+) operators [4 (80 %) AEF (+) vs. 2 (10 %) AEF (?), p?=?0.002]. There was a trend towards higher maximal RF energy setting in the posterior wall [47.4 + 7.6 AEF (+) vs. 40.2 + 8 AEF (?), p?=?0.09]. Other procedure parameters were similar.

Conclusions

The reported prevalence of AEF among Canadian AF ablators is 0.07 %. AEF was associated with high mortality. The use of GA and non-brushing movements during posterior wall ablation were two factors associated with AEF.     

Changes in peripheral blood CD5 (Bla) B-cell populations and autoantibodies following blood transfusion

BACKGROUND: CD5 B cells and the natural autoantibodies they produce play a role in antigen presentation, tolerance induction, and maintenance of an idiotypic immune network. The effects of transfusion on autoantibodies and peripheral blood CD5 B cells were studied. STUDY DESIGN AND METHODS: Eight previously transfused patients with sickle cell anemia and five patients who underwent orthopedic surgical procedures with transfusion were enrolled in the study. Patients in both groups received 1 to 2 units of allogeneic packed red cells. Ten untransfused healthy adults and five patients who underwent orthopedic surgery without transfusion were enrolled as controls. Peripheral blood CD5 B cells, serum levels of IgM, antinuclear antibodies, rheumatoid factor, and anticardiolipin IgM were quantitated either at the beginning of the study (baseline sample), before transfusion, or before surgery and either at 1-, 2-, 4-, 6-, and 8-week intervals after transfusion, after surgery, or after the baseline sample was obtained. RESULTS: IgM levels and the absolute number of B cells that coexpressed CD5 rose to twice pretransfusion levels in six of eight transfused sickle cell anemia patients and in four of five transfused orthopedic surgery patients. No comparable increases in CD5 B cells were noted in untransfused controls. Preexisting rheumatoid factor and antinuclear antibody levels increased in four of five transfused orthopedic surgery patients. One sickle cell anemia patient developed anti-Fya despite receiving Fya-negative blood. Increasing titers of anti-Fya paralleled the increases in IgM and CD5 B cells after transfusion. One patient who developed a positive direct antiglobulin test after transfusion had large increases in serum anticardiolipin IgM. Anticardiolipin IgM was subsequently eluted from direct antiglobulin test-positive red cells obtained after transfusion. Antibodies with anti-Fya-like activity and anticardiolipin IgM were produced in vitro by CD5 B cells and not by conventional CD5-negative B cells. CONCLUSION: An association was found between transfusion-induced increases in CD5 B cells and increased autoantibody production. These data may have implications for immunologic intervention to prevent the induction of red cell antibodies and other changes in the immune system caused by exposure to foreign antigens via blood transfusion.     

Dysglycemias in pregnancy: from diagnosis to treatment. Brazilian consensus statement

There is an urgent need to find consensus on screening, diagnosing and treating all degrees of DYSGLYCEMIA that may occur during pregnancies in Brazil, considering that many cases of DYSGLYCEMIA in pregnant women are currently not diagnosed, leading to maternal and fetal complications. For this reason the Brazilian Diabetes Society (SBD) and the Brazilian Federation of Gynecology and Obstetrics Societies (FEBRASGO), got together to introduce this proposal. We present here a joint consensus regarding the standardization of clinical management for pregnant women with any degree of Dysglycemia, on the basis of current information, to improve medical assistance and to avoid related complications of Dysglycemia in pregnancy to the mother and the fetus. This consensus aims to standardize the diagnosis among general practitioners, endocrinologists and obstetricians allowing the dissemination of information in basic health units, public and private services, that are responsible for screening, diagnosing and treating disglycemic pregnant patients.     

Amphotericin B-Gum Arabic Conjugates: Synthesis, Toxicity, Bioavailability, and Activities Against Leishmania and Fungi

Purpose Gum arabic, a branched polysaccharide consisting of more than 90% arabinogalactan having a molecular weight around 250,000 Da is the oldest and best known of all natural gums. The objective of the present investigation was to examine whether amphotericin B (AmB), the polyene antibiotic when conjugated to periodate oxidized gum arabic still retained its anti-fungal and anti-leishmanial activity and to evaluate its toxicity and bioavailability. Methods AmB conjugated to the oxidized polysaccharide through Schiff’s linkages in the unreduced (imine) and reduced (amine) forms were characterized for the drug content, hemolytic potential, molecular mass, in vitro release and were examined for anti-fungal activity against Candida albicans and Cryptococcus neoformans and for anti-leishmanial activity against promastigotes of Leishmania donovani in culture. Toxicity and bioavailability were evaluated by intravenous (i.v) injections of the conjugates in mice and rabbits respectively. Results The conjugates were found to be non-hemolytic and mice withstood a dosage of 20 mg (AmB)/kg body weight of both conjugates. Histological examination of the internal organs of mice showed no lesions in kidney, brain, heart or liver. Estimation of the residual drug in the internal organs 7 days post injection showed that the spleen still retained 8.4 ± 0.53 μg/g of tissue. AmB was found to be released from both conjugates in vitro although the release from the imine conjugate was much faster than from the amine conjugate. The concentrations inhibiting parasite growth by 50% (IC₅₀) values for the imine conjugate against promastigotes of L. donovani LV9 and DD8 strains were 0.37 ± 0.04 and 1.44 ± 0.18 μM respectively. The IC₅₀ values for the amine conjugates were much higher. The minimum inhibitory concentration (MIC) against C. albicans and C. neoformans was in the range of 0.5–0.9 μg/mL for both imino and amino conjugates. The bioavailability of the conjugate in rabbits showed that the imine conjugate maintained a plasma concentration in the range of 20 to 5 μg/mL while for the amine conjugate it was in the range of 17 to 3 μg/mL over 24 h. Conclusions The drug conjugates were stable, non-hemolytic and non-toxic to the internal organs of the animal and showed good anti-fungal and anti-leishmanial activity in vitro. In spite of the large molecular weight of the polysaccharide, AmB from the conjugates showed bioavailability after i.v injection. Since the highest concentration of AmB was found in the spleen after a single injection, these conjugates may have potential in anti-leishmanial therapy. A. J dedicates this paper to Prof. M. S. Valiathan for his 72nd birthday.     

Enabling a robust scalable manufacturing process for therapeutic exosomes through oncogenic immortalization of human ESC-derived MSCs

Background  

Exosomes or secreted bi-lipid vesicles from human ESC-derived mesenchymal stem cells (hESC-MSCs) have been shown to reduce myocardial ischemia/reperfusion injury in animal models. However, as hESC-MSCs are not infinitely expansible, large scale production of these exosomes would require replenishment of hESC-MSC through derivation from hESCs and incur recurring costs for testing and validation of each new batch. Our aim was therefore to investigate if MYC immortalization of hESC-MSC would circumvent this constraint without compromising the production of therapeutically efficacious exosomes.     

Interesting case of dual tachycardia in a patient with surgical closure of atrial septal defect

A 34‐year‐old gentleman, who had undergone pericardial patch closure of ostium secundum atrial septal defect (ASD) at 8 years of age, was evaluated for shortness of breath. Electrocardiogram revealed typical atrial flutter with varying atrioventricular conduction. Echocardiogram showed no residual ASD or pulmonary hypertension and good biventricular function. He was taken for an electrophysiological study with the intention of radiofrequency ablation of the typical flutter.     

Pre-clinical evaluation of titanium nitride coated titanium material

The titanium nitride coated titanium is a material intended for the fabrication of left ventricular assist device. As per International standards, a material is subjected to pre-clinical evaluation before fabrication of a device. Toxicity/biocompatibility studies such as acute systemic toxicity, intracutaneous irritation, in vitro haemolysis and implantation in muscle were studied as per international standards for the titanium nitride coated titanium. Acute systemic toxicity was studied in mice using physiological saline and cotton seed oil extracts of the material. Intracutaneous irritation was done by injecting the extracts of the test material and control intradermally into rabbits. Grading of erythema and oedema of test and control animals were recorded at 24, 48 and 72?h. In vitro haemolysis was carried out with material and extract of the material with rabbit blood. The muscle implantation was carried out in nine anesthetized rabbits. The implanted animals were sacrificed at the end of 1, 4 and 12 weeks, the tissue with the implanted materials were collected and subjected to histopathological analysis. The results of the study did not show any significant irritation or systemic toxicity with physiological saline and cotton seed oil extracts of the material. The percentage of hemolysis induced by the material and extract was under acceptable range. Results of the histopathological evaluation suggest that the test material did not produce any cellular changes. Hence the present study concluded that the test material is non-toxic, non-irritant, non-haemolytic and biocompatible.