Effects of opsonization and gamma interferon on growth of Brucella melitensis 16M in mouse peritoneal macrophages in vitro

Entry of opsonized pathogens into phagocytes may benefit or, paradoxically, harm the host. Opsonization may trigger antimicrobial mechanisms such as reactive oxygen or nitric oxide (NO) production but may also provide a safe haven for intracellular replication. Brucellae are natural intramacrophage pathogens of rodents, ruminants, dogs, marine mammals, and humans. We evaluated the role of opsonins in Brucella-macrophage interactions by challenging cultured murine peritoneal macrophages with Brucella melitensis 16M treated with complement- and/or antibody-rich serum. Mouse serum rich in antibody against Brucella lipopolysaccharide (LPS) (aLPS) and human complement-rich serum (HCS) each enhanced the macrophage uptake of brucellae. Combinations of suboptimal levels of aLPS (0. 01%) and HCS (2%) synergistically enhanced uptake. The intracellular fate of ingested bacteria was evaluated with an optimal concentration of gentamicin (2 microg/ml) to control extracellular growth but not kill intracellular bacteria. Bacteria opsonized with aLPS and/or HCS grew equally well inside macrophages in the absence of gamma interferon (IFN-gamma). Macrophage activation with IFN-gamma inhibited replication of both opsonized and nonopsonized brucellae but was less effective in inhibiting replication of nonopsonized bacteria. IFN-gamma treatment of macrophages with opsonized or nonopsonized bacteria enhanced NO production, which was blocked by N(G)-monomethyl L-arginine (MMLA), an NO synthesis inhibitor. MMLA also partially blocked IFN-gamma-mediated bacterial growth inhibition. These studies suggest that primary murine macrophages have limited ability to control infection with B. melitensis, even when activated by IFN-gamma in the presence of highly opsonic concentrations of antibody and complement. Additional cellular immune responses, e.g., those mediated by cytotoxic T cells, may play more important roles in the control of murine brucellosis.     

Determination of serum and organ malondialdehyde (MDA) concentration, a lipid peroxidation index, in Trypanosoma brucei-infected rats

Lipid peroxidation was assessed in the sera and various organs of rats experimentally infected with Trypanosoma brucei. Thirty-six adult albino rats divided into 2 groups of eighteen rats each were used in this study. In experiment one, a group of 18 rats were used and they were divided into three groups (A, B and C) of six rats each. Groups B and C rats were infected with 1.54 × 10⁵ trypanosomes per rat intraperitoneally, whereas group A served as uninfected control. The rats were bled on day 0 and subsequently at 7-day intervals for packed cell volume (PCV), sera peroxidation index and parasitaemia. Also, temperature and weight were taken on day 0 and subsequently at 7-day intervals. In experiment 2, 18 rats were also used. Six rats each were sacrificed on days 0, 14 and 28-postinfection. Five rats each were sacrificed on day 14 and day 28 post-infection (PI) from group B, and their organs were promptly collected and washed with normal saline and used for organ malondialdehyde (MDA) concentration. The infection led to an increase in lipid peroxidation index (MDA concentration) of sera samples. The serum MDA concentration of the infected rat group was significantly (p < 0.01) higher than in the uninfected group on days 21 and 28 PI. The increase was however reversed by diminazene aceturate (Berenil; Hoechst, Ireland) treatment at the dosage of 7 mg/kg body weight administered on day 14 PI. The organ lipid peroxidation index also increased significantly (p < 0.05) in the eye, lung and spleen. However, there was no significant (p > 0.05) increase of lipid peroxidation index in the kidney, heart, liver, testes and brain. Also, the mean weekly MDA concentration increased as the disease progressed, the mean weekly temperature and parasitaemia also increased, but the reverse was the case with the mean weekly body weight and PCV which declined as the disease progressed. The findings are indication that oxidative stress plays an important role in the pathology of trypanosomosis.     

The immunology of Leishmania/HIV co-infection

Leishmaniases are emerging as an important disease in human immunodeficiency virus (HIV)–infected persons living in several sub-tropical and tropical regions around the world, including the Mediterranean. The HIV/AIDS pandemic is spreading at an alarming rate in Africa and the Indian subcontinent, areas with very high prevalence of leishmaniases. The spread of HIV into rural areas and the concomitant spread of leishmaniases to suburban/urban areas have helped maintain the occurrence of Leishmania/HIV co-infection in many parts of the world. The number of cases of Leishmania/HIV co-infection is expected to rise owing to the overlapping geographical distribution of the two infections. In Southwestern Europe, there is also an increasing incidence of Leishmania/HIV co-infection (particularly visceral leishmaniasis) in such countries as France, Italy, Spain and Portugal. Studies suggest that in humans, very complex mechanisms involving dysregulation of host immune responses contribute to Leishmania-mediated immune activation and pathogenesis of HIV. In addition, both HIV-1 and Leishmania infect and multiply within cells of myeloid or lymphoid origin, thereby presenting a perfect recipe for reciprocal modulation of Leishmania and HIV-1-related disease pathogenesis. Importantly, because recovery from leishmaniases is associated with long-term persistence of parasites at the primary infection sites and their draining lymph nodes, there is very real possibility that HIV-mediated immunosuppression (due to CD4⁺ T cell depletion) could lead to reactivation of latent infections (reactivation leishmaniasis) in immunocompromised patients. Here, we present an overview of the immunopathogenesis of Leishmania/HIV co-infection and the implications of this interaction on Leishmania and HIV disease outcome.     

Colon Interposition Graft for Corrosive Esophageal Stricture: Midterm Functional Outcome

Background

Corrosive esophageal stricture is a major cause of morbidity among Nigerians. In most cases, this follows accidental or parasuicidal ingestion of caustic sodium hydroxide solution (NaOH) often used in the local production of soaps. Various treatment modalities have been advocated for the treatment of esophageal stricture. In this study, we review the results of our adopted technique in the past 10 years for pedicled colonic interposition.

Methods

This is a retrospective study of 21 patients who underwent substernal isoperistaltic pedicled colonic interposition graft for management of corrosive esophageal stricture. The right colon was pulled up into the neck in all the patients without resecting the strictured esophagus.

Results

Long segment strictures and multiple strictures were the main indications for the procedure. The mean duration of the procedure was 339.6 ± 71.1 min. The average intraoperative blood loss was 673.1 ± 398.1 mL. There were two (9.5 %) hospital mortalities. Graft infarction (9.5 %), cervical fistulae (19.0 %), and reflux neo-esophagitis (14.3 %) were the main non-fatal complications. In the mid-term, dysphagia was completely relieved in a little over 84 % (16/19) of patients, while one patient (4.8 %) still experienced reflux neo-esophagitis requiring treatment. There was no case of gross regurgitation or nocturnal aspiration in the mid-term.

Conclusions

Although the use of pedicled colonic interposition graft offers a good mid-term functional outcome with relief of dysphagia, early postoperative morbidity is high. Graft infarction is the single most important factor for poor functional outcome and every effort must be made to prevent its occurrence.     

Development of rapid and selective epoxidation of α-pinene using single-step addition of H2O2 in an organic solvent-free process

This study reports substantial improvement in the process for oxidising α-pinene, using environmentally friendly H₂O₂ at high atom economy (∼93%) and selectivity to α-pinene oxide (100%). The epoxidation of α-pinene with H₂O₂ was catalysed by tungsten-based polyoxometalates without any solvent. The variables in the screening parameters were temperatures (30–70 °C), oxidant amount (100–200 mol%), acid concentrations (0.02–0.09 M) and solvent types (i.e., 1,2-dichloroethane, toluene, p-cymene and acetonitrile). Screening the process parameters revealed that almost 100% selective epoxidation of α-pinene to α-pinene oxide was possible with negligible side product formation within a short reaction time (∼20 min), using process conditions of a 50 °C temperature in the absence of solvent and α-pinene/H₂O₂/catalyst molar ratio of 5 : 1 : 0.01. A kinetic investigation showed that the reaction was first-order for α-pinene and catalyst concentration, and a fractional order (∼0.5) for H₂O₂ concentration. The activation energy (E_a) for the epoxidation of α-pinene was ∼35 kJ mol⁻¹. The advantages of the epoxidation reported here are that the reaction could be performed isothermally in an organic solvent-free environment to enhance the reaction rate, achieving nearly 100% selectivity to α-pinene oxide.

Products obtained from the oxidation of α-pinene with hydrogen peroxide (H₂O₂) in the presence of tungsten-based polyoxometalates (α-pinene 1, α-pinene oxide 2, pinanediol 3, campholenic aldehyde 4, sobrerol 5, verbenol 6 and verbenone 7).     

The role of the anterior cricoid split in facilitating extubation in infants

OBJECTIVE: The use of the anterior cricoid split (ACS) procedure has facilitated the extubation of children with early subglottic stenosis who may otherwise have required a tracheostomy. Criteria have been established for the evaluation of patients suitable for ACS and adherence to these guidelines has increased the extubation rate and reduced mortality. The objective of the study was to assess the use of the procedure at our tertiary referral centre. METHOD: In this retrospective clinical study, 33 patients were identified over an 11-year period between 1993 and 2004 with subglottic narrowing at the level of the cricoid ring, and who subsequently underwent an ACS. Demographic data, duration of intubation, indication and number of reintubations, success rate and complications were noted. Patients included in the study were infants who repeatedly failed trials of extubation and those who presented with persistent stridor. RESULTS: Twenty-nine out of 33 (88%) children were successfully extubated as a result of the cricoid split procedure. Four children failed extubation after the cricoid split. Three required a tracheostomy and one child remained intubated for a prolonged period. CONCLUSION: The anterior cricoid split procedure has revolutionised the management of early subglottic stenosis in selected neonates with failed extubation. It is a safe operation, and if successful it avoids the formation of a tracheostomy.     

Preferences for benefit packages for community-based health insurance: an exploratory study in Nigeria

Background  

It is important that community-based health insurance (CBHI) schemes are designed in such a way as to ensure the relevance of the benefit packages to potential clients. Hence, this paper provides an understanding of the preferred benefit packages by different economic status groups as well as urban and rural dwellers for CBHI in Southeast Nigeria.