Reliability Testing of the MOD 3-T Two Axis Dynamically Tuned Gyroscope

Testing program to determine the long-term performance characteristics of the Textron Defense Systems' MOD 3-T Two-Axis Dynamically Tuned Gyroscope is reported

Leishmania donovani: Immunostimulatory Cellular Responses of Membrane and Soluble Protein Fractions of Splenic Amastigotes in Cured Patient and Hamsters

Visceral leishmaniasis (VL), caused by the intracellular parasite Leishmania donovani, L. chagasi and L. infantum is characterized by defective cell-mediated immunity (CMI) and is usually fatal if not treated properly. An estimated 350 million people worldwide are at risk of acquiring infection with Leishmania parasites with approximately 500,000 cases of VL being reported each year. In the absence of an efficient and cost-effective antileishmanial drug, development of an appropriate long-lasting vaccine against VL is the need of the day. In VL, the development of a CMI, capable of mounting Th1-type of immune responses, play an important role as it correlate with recovery from and resistance to disease. Resolution of infection results in lifelong immunity against the disease which indicates towards the feasibility of a vaccine against the disease. Most of the vaccination studies in Leishmaniasis have been focused on promastigote- an infective stage of parasite with less exploration of pathogenic amastigote form, due to the cumbersome process of its purified isolation. In the present study, we have isolated and purified splenic amastigotes of L. donovani, following the traditional protocol with slight modification. These were fractionated into five membranous and soluble subfractions each i.e MAF1-5 and SAF1-5 and were subjected for evaluation of their ability to induce cellular responses. Out of five sub-fractions from each of membrane and soluble, only four viz. MAF2, MAF3, SAF2 and SAF3 were observed to stimulate remarkable lymphoproliferative, IFN-γ, IL-12 responses and Nitric Oxide production, in Leishmania-infected cured/exposed patients and hamsters. Results suggest the presence of Th-1 type immunostimulatory molecules in these sub-fractions which may further be exploited for developing a successful subunit vaccine from the less explored pathogenic stage against VL

In Vitro Evaluation of a Soluble Leishmania Promastigote Surface Antigen as a Potential Vaccine Candidate against Human Leishmaniasis

International audiencePSA (Promastigote Surface Antigen) belongs to a family of membrane-bound and secreted proteins present in severalLeishmania (L.) species. PSA is recognized by human Th1 cells and provides a high degree of protection in vaccinated mice.We evaluated humoral and cellular immune responses induced by a L. amazonensis PSA protein (LaPSA-38S) produced in aL. tarentolae expression system. This was done in individuals cured of cutaneous leishmaniasis due to L. major (CCLm) or L.braziliensis (CCLb) or visceral leishmaniasis due to L. donovani (CVLd) and in healthy individuals. Healthy individuals weresubdivided into immune (HHR-Lm and HHR-Li: Healthy High Responders living in an endemic area for L. major or L. infantuminfection) or non immune/naive individuals (HLR: Healthy Low Responders), depending on whether they produce high orlow levels of IFN-c in response to Leishmania soluble antigen. Low levels of total IgG antibodies to LaPSA-38S were detectedin sera from the studied groups. Interestingly, LaPSA-38S induced specific and significant levels of IFN-c, granzyme B and IL-10 in CCLm, HHR-Lm and HHR-Li groups, with HHR-Li group producing TNF-a in more. No significant cytokine response wasobserved in individuals immune to L. braziliensis or L. donovani infection. Phenotypic analysis showed a significant increasein CD4+ T cells producing IFN-c after LaPSA-38S stimulation, in CCLm. A high positive correlation was observed between thepercentage of IFN-c-producing CD4+ T cells and the released IFN-c. We showed that the LaPSA-38S protein was able toinduce a mixed Th1 and Th2/Treg cytokine response in individuals with immunity to L. major or L. infantum infectionindicating that it may be exploited as a vaccine candidate. We also showed, to our knowledge for the first time, the capacityof Leishmania PSA protein to induce granzyme B production in humans with immunity to L. major and L. infantum infectio

Outcomes after transvenous defibrillator implantation in cardiac sarcoidosis: A systematic review

Introduction Sarcoidosis is a systemic inflammatory disorder associated with ventricular arrhythmias (VAs) and sudden death in the context of cardiac involvement. Guidelines advocate implantable cardioverter-defibrillator (ICD) implantation in specific subcohorts, but there is a paucity of data on outcomes. Methods and Results A systematic review was performed to assess outcomes in patients with definite or probable cardiac sarcoidosis (CS) treated with ICD. Observational studies were identified from multiple databases from inception to 21st May 2021. Outcomes of interest included appropriate and inappropriate ICD therapies in addition to all-cause mortality. Study quality was assessed individually using the Newcastle Ottawa Scale (NOS). Eight studies were identified comprising 530 patients, with follow-up period of 24–66 months (weighted average 40 months). Mean age was 53.9 years with ejection fraction of 41.3%. Overall incidence of appropriate therapy was 38.1% during follow-up. Left ventricular systolic dysfunction (LVSD) with ejection fraction <40% was a predictor of appropriate therapy in the majority of studies, as were sustained VAs during electrophysiological testing (EP) in one study. There was no interaction with device indication (i.e. primary or secondary). Where documented, inappropriate therapy was primarily driven by atrial arrhythmias. All-cause mortality was 6.0% over a median follow-up period of 42 months. Only three studies achieved good quality in the comparability domain of NOS. Conclusions Appropriate ICD therapy in patients with CS is commonly associated with LVSD, which can act as a surrogate for scar burden. The utility of EP testing in this setting remains unclear

Pentoxifylline treatment of mice with chronic pulmonary tuberculosis accelerates the development of destructive pathology

It is well established in animal models that production of the cytokine tumour necrosis factor-α (TNF-α) is essential to the proper expression of acquired specific resistance following infection with Mycobacterium tuberculosis. This gives rise to an apparent state of chronic disease which over the next 100–200 days is characterized by slowly worsening pathological changes in the lung. To determine whether continued TNF-α production was harmful during this phase mice were treated with a TNF-α inhibitor, pentoxifylline. It was observed that although this therapy did not alter the numbers of bacteria recovered from the lungs of the infected mice, tissue damage within the lung was accelerated. These data thus demonstrate that production of TNF-α, already known to be important during the early expression of resistance to tuberculosis, remains important and beneficial during the chronic stage of the disease

Apoptosis of Mycobacterium avium-infected macrophages is mediated by both tumour necrosis factor (TNF) and Fas, and involves the activation of caspases

Mycobacterium avium causes disseminated infection in AIDS patients and several forms of infection in immunocompetent hosts. Recent studies have shown that M. avium infection of macrophages in vitro leads to apoptosis of significant numbers of infected cells. Several strains of M. avium used to infect human macrophages for 5 days (multiplicity of infection of 10) triggered 28–46% higher levels of apoptosis than observed with uninfected macrophages at the same time points. Mycobacterium avium strains unable to replicate intracellularly (rep−) resulted in a 15% rate of apoptosis, while M. smegmatis-infected monolayers showed the same percentage of apoptotic cells as the uninfected macrophage control. The presence of anti-TNF-α antibody reduced apoptosis to 17% and the presence of anti-Fas antibody reduced apoptosis to 10%. When both antibodies were used together, the apoptosis level was 5% above the control. Treatment with TGF-β also reduced the number of apoptotic cells in infected monolayers. If intracellular growth was inhibited, apoptosis of macrophages decreased significantly. It was also shown that apoptosis was associated with IL-1β-converting enzyme (ICE) activation and was significantly reduced by a caspase inhibitor. Gaining understanding of the mechanisms of M. avium-associated apoptosis of macrophages will provide important insight into M. avium pathogenesis

Differential gene expression in mononuclear phagocytes infected with pathogenic and non-pathogenic mycobacteria

The pathogenic mycobacteria are an insidious group of bacterial pathogens that cause the deaths of millions of people every year. One of the reasons these pathogens are so successful is that they are able to invade and replicate within host macrophages, one of the first lines of defence against intruding pathogens. In contrast, non-pathogenic mycobacteria, such as Mycobacterium smegmatis are killed rapidly by macrophages. In order to understand better the series of events that allow pathogenic mycobacteria to survive and replicate within macrophages, while the non-pathogenic mycobacteria are killed rapidly, we inoculated the human monocytic cell line U937 with pathogenic (M. tuberculosis and M. avium) and non-pathogenic (M. smegmatis) mycobacteria and monitored the expression of over 3500 genes at 4, 12 and 24 h post-inoculation using a commercially available gene array system. We observed multiple differences in the gene expression patterns of monocytes infected with pathogenic and non-pathogenic mycobacteria including genes involved in cytokine, lymphokine and chemokine production, adhesion, apoptosis, signal transduction, transcription, protein cleavage, actin polymerization and growth. We also observed differences in gene expression profiles in monocytes infected with M. tuberculosis or M. avium, indicating that there are differences in the host pathogen interactions of mononuclear phagocytes infected with different pathogenic mycobacterial species. These results increase the understanding of the mechanisms used by pathogenic mycobacteria to cause disease, the host response to these organisms, and provide new insights for antimycobacterial intervention strategies

Immunostimulatory cellular responses of cured Leishmania-infected patients and hamsters against the integral membrane proteins and non-membranous soluble proteins of a recent clinical isolate of Leishmania donovani

Development of an effective immunoprophylactic agent for visceral leishmaniasis (VL) has become imperative due to the increasing number of cases of drug resistance and relapse. Live and killed whole parasites as well as fractionated and recombinant preparations have been evaluated for vaccine potential. However, a successful vaccine against the disease has been elusive. Because protective immunity in human and experimental leishmaniasis is predominantly of the Th1 type, immunogens with Th1 stimulatory potential would make good vaccine candidates. In the present study, the integral membrane proteins (IMPs) and non-membranous soluble proteins (NSPs), purified from promastigotes of a recent field isolate, Leishmania donovani stain 2001, were evaluated for their ability to induce cellular responses in cured patients (n = 9), endemic controls (n = 5) of visceral leishmaniasis (VL) and treated hamsters (n = 10). IMPs and NSPs induced significant proliferative responses (SI 6·3 ± 4·1 and 5·6 ± 2·3, respectively; P < 0·01) and IFN-γ production (356·3 ± 213·4 and 294·29 ± 107·6 pg/ml, respectively) in lymphocytes isolated from cured VL patients. Significant lymphoproliferative responses against IMPs and NSPs were also noticed in cured Leishmania animals (SI 7·2 ± 4·7 & 6·4 ± 4·1, respectively; P < 0·01). In addition, significant NO production in response both IMPs and NSPs was also noticed in macrophages of hamsters and different cell lines (J774A-1 and THP1). These results suggest that protective, immunostimulatory molecules are present in the IMP and NSP fractions, which may be exploited for development of a subunit vaccine for VL