Humoral and cellular immune responses to synthetic peptides of the Leishmania donovani kinetoplastid membrane protein-11

Native kinetoplastid membrane protein-11 (KMP-11), purified from crude extracts of Leishmania donovani parasites, activates T cells from individuals who have recovered from visceral leishmaniasis. In this work we used three 38-mer peptides spanning the amino acid sequence of the L. donovani KMP-11 as solid-phase ligands in enzyme-linked immunosorbent assays (ELISAs) and as stimulating antigens in lymphoproliferative assays in order to evaluate humoral and cellular immune responses to well-defined sequences of the protein. Antibody reactivity against the three peptides was measured in plasma from 63 Sudanese visceral leishmaniasis patients (VL) and the percentage of patients with anti-KMP-11 antibodies in ELISA were 37% (KMP-11-1), 30% (KMP-11-2) and 58% (KMP-11-3). The fraction of VL patients with measurable antibody reactivity in one or more of the three ELISAs was 79%. Cross-reactivity to the KMP-11 peptides was detected in plasma from Sudanese patients suffering from Leishmania major infections and in plasma from Sudanese and Danish patients infected with Plasmodium falciparum. In lymphoproliferative assays, 10 of 17 PBMC isolates from donors previously infected with L. donovani showed a response to one or more of the three KMP-11 peptides.

The Leishmania promastigote surface antigen-2 (PSA-2) is specifically recognised by Th1 cells in humans with naturally acquired immunity to L. major

The promastigote surface antigen-2 (PSA-2) is a Leishmania parasite antigen, which can induce Th1-mediated protection against murine leishmaniasis when used as a vaccine. To evaluate PSA-2 as a human vaccine candidate the specific T-cell response to PSA-2 was characterised in individuals immune to cutaneous leishmaniasis. Peripheral blood mononuclear cells from Sudanese individuals with a past history of self-healing cutaneous leishmaniasis proliferated vigorously in response to PSA-2 isolated from Leishmania major, whereas the antigen did not activate cells from presumably unexposed Danes. Peripheral blood mononuclear cells from individuals with previous L. major infection had varying proliferative responses to PSA-2 derived from L. donovani promastigotes. Peripheral blood mononuclear cells activated by PSA-2 from L. major produced high amounts of interferon-gamma and tumour necrosis factor-beta, and little interleukin-4, thereby showing a Th1 cytokine pattern. Parallel cultures showed clear Th1 and Th2 response patterns to purified protein derivative of tuberculin or tetanus toxoid, respectively. Flow cytometric analysis revealed that PSA-2 induced blastogenesis in the CD3 positive population and that these cells were the major source of interferon-gamma. The results show that Th1-like cells recognising PSA-2 are expanded during infection by L. major and that they maintain their Th1-like cytokine profile upon reactivation in vitro. Since immunity to cutaneous leishmaniasis is mediated by antigen-specific Th1-like cells, PSA-2 might be considered a vaccine candidate for human leishmaniasis.

Gastro-intestinal protein loss in late survivors of Fontan surgery and other congenital heart disease

AIMS

Protein losing enteropathy is a serious complication of Fontan surgery. The aim of this study was to investigate gastro-intestinal protein loss in adults with congenital heart disease, both with and without Fontan surgery, and to correlate findings with systemic venous pressure.

METHODS AND RESULTS

Forty eight patients were studied. The first group included adult survivors of Fontan surgery. The second and third groups were control patients with congenital heart disease who had not had Fontan surgery and had either normal or chronically elevated systemic venous pressure. Gastro-intestinal protein loss was assessed by measurement of faecal alpha-1-antitrypsin. Faecal alpha-1-antitrypsin levels were significantly higher in the Fontan group (0.55 +/- 0.15 mg. g-1 faeces, P = 0.002) and the control group with chronically elevated venous pressure (0.60 +/- 0.30 mg. g-1 faeces, P < 0.001) compared to the controls with normal venous pressure (0.29 = 0.12 mg. g-1 faeces). Of the 15 subjects who were found to have increased gastro-intestinal protein loss, only four had clinical protein-losing enteropathy. The degree of gastro-intestinal protein loss correlated significantly with venous pressure (P = 0.01) and with serum aspartate transaminase (P = 0.04).

CONCLUSION

Increased gastro-intestinal protein loss is common in this select group of late survivors of Fontan surgery and in other subjects with congenital heart disease and chronic elevation of systemic venous pressure, and was present in patients who did not have protein-losing enteropathy. Increased faecal alpha-1-antitrypsin is an important finding in these patients as intervention at this stage, before the onset of florid protein-losing enteropathy, might prevent the development of further complications.

[Penicillin resistant pneumococci--not a threat in Denmark yet?]

The occurrence of penicillin resistance in clinical isolates of pneumococci was investigated in two clinical microbiological laboratories in Copenhagen, Denmark. One of the laboratories predominantly received samples from patients with frequent use of antibiotics mainly because of chronic lung diseases. In this laboratory, 6.3% of 245 isolates of pneumococci had intermediate resistance to penicillin. In the other laboratory, which received samples from a number of hospitals and general practice, only 1.3% of isolates of pneumococci had reduced sensitivity to penicillin. Penicillin-resistant pneumococci are rare in Denmark, but are more prevalent in patients who frequently use antibiotics.

Interferon-gamma production by human T cells and natural killer cells in vitro in response to antigens from the two intracellular pathogens Mycobacterium tuberculosis and Leishmania major

Acquired resistance to both mycobacteria and Leishmania is primarily mediated by interferon-gamma (IFN-gamma), which triggers mechanisms leading to the death of the microorganism in macrophages. In this study, cell activation and IFN-gamma production was investigated in human peripheral blood mononuclear cells (PBMC) from individuals previously sensitized to tuberculin and without known exposure to Leishmania parasites. Immune staining for intracellular IFN-gamma and surface markers allowed flow cytometric identification of the cellular sources of IFN-gamma in cell cultures incubated with purified protein derivative of tuberculin (PPD) and Leishmania antigens. It was found that IFN-gamma was produced in response to both PPD and Leishmania stimulant by T cells in the cultures. Activation of IFN-gamma producing natural killer (NK) cells was demonstrated only in some cultures, and only with concomitant T cell activation.

Tumor necrosis factor and steroid metabolism in chronic heart failure: possible relation to muscle wasting

OBJECTIVES

We sought to assess the possible relations between clinical severity of chronic heart failure and catabolic factors, specifically tumor necrosis factor (TNF), soluble TNF receptors 1 and 2 (sTNFR-1 and sTNFR-2), cortisol, testosterone and dehydroepiandrosterone (DHEA).

BACKGROUND

Chronic heart failure is associated with loss of muscle bulk that may be related to alteration of the balance between catabolism and anabolism.

METHODS

Sixty-three patients (average age +/- SD 60.4 +/- 11.3 years) with stable chronic heart failure and 20 control subjects aged 52.8 +/- 11.4 years were studied. We measured body mass index (BMI) and obtained maximal incremental exercise testing with metabolic gas exchange measurements and measurements of venous levels of TNF, sTNFR-1 and sTNFR-2, cortisol and DHEA.

RESULTS

There was no difference in total TNF-alpha levels between patients and control subjects (9.76 +/- 8.59 vs. 6.84 +/- 2.7 pg/ml). sTNFR-1 (128.9 +/- 84.5 vs. 63.6 +/- 23.3 pg/ml, p < 0.003) and sTNFR-2 (250.1 +/- 109.5 vs. 187.9 +/- 92.2 pg/ml, p = 0.03) were higher in patients. DHEA was lower in patients (9.88 +/- 6.94 vs. 15.64 +/- 8.33 nmol/liter, p = 0.004). The ratio of log cortisol to log DHEA correlated with log TNF level (r = 0.50, p < 0.001 for the patients alone; r = 0.48, p < 0.001 for the group as a whole). Peak oxygen consumption correlated with both sTNFR-1 and sTNFR-2 (r = -0.51, p < 0.001 and r = -0.39, p < 0.001, respectively). There was a negative correlation between BMI and TNF levels (r = -0.43, p < 0.001 for the patients) and the cortisol/DHEA ratio (r = -0.32, p = 0.01 for the patients).

CONCLUSIONS

There is an increase in TNF and its soluble receptors in chronic heart failure. This increase is associated with a rise in the cortisol/DHEA (catabolic/anabolic) ratio. These changes correlate with BMI and clinical severity of heart failure, suggesting a possible etiologic link.

Finding and using inter-war maternity records

This paper describes the results of a search for the obstetric records of a cohort of over 5,000 children who participated in surveys of childhood diet and growth during the late 1930s and early 1940s conducted by the Rowett Research Institute in Aberdeen. The surveys were conducted at sixteen centres throughout England and Scotland. Birth-weight data were found in hospitals, health authority archives and local authority record offices for approximately 10 per cent of these children. The sources and methods used to find the records are described and their representativeness is evaluated. It is anticipated that this report will be of some interest to medical historians and epidemiologists conducting retrospective studies.

Ischaemic preconditioning reduces troponin T release in patients undergoing coronary artery bypass surgery

OBJECTIVE

To investigate whether ischaemic preconditioning could reduce myocardial injury, as manifest by troponin T release, in patients undergoing elective coronary artery bypass surgery.

DESIGN

Randomised controlled trial.

SETTING

Cardiothoracic unit of a tertiary care centre.

PATIENTS

Patients with three vessel coronary artery disease and stable angina admitted for first time elective coronary artery bypass surgery were invited to take part in the study; 33 patients were randomised into control or preconditioning groups.

INTERVENTION

Patients in the preconditioning group were exposed to two additional three minute periods of myocardial ischaemia at the beginning of the revascularisation operation, before the ischaemic period used for the first coronary artery bypass graft distal anastomosis.

MAIN OUTCOME MEASURE

Serum troponin T concentration at 72 hours after cardiopulmonary bypass.

RESULTS

The troponin T assays were performed by blinded observers at a different hospital. All patients had undetectable serum troponin T (< 0.1 microgram/l) before cardiopulmonary bypass, and troponin T was raised postoperatively in all patients. At 72 hours, serum troponin T was lower (P = 0.05) in the preconditioned group (median 0.3 microgram/l) than in the control group (median 1.4 micrograms/l).

CONCLUSIONS

The direct application of a preconditioning stimulus in clinical practice has been shown, for the first time, to protect patients against irreversible myocyte injury.

Effects of age and ischemic times on biochemical evidence of myocardial injury after pediatric cardiac operations

INTRODUCTION

The vulnerability of pediatric myocardium to ischemia is poorly documented in the clinical setting.

METHODS

Serial measurements of serum concentrations of myoglobin, the MB isoenzyme of creatine kinase, and cardiac troponins T and I and their respective areas under the curve were obtained, with particular reference to age and ischemic time, in 80 children undergoing cardiac operations. Sixteen (the control group) did not require cardiopulmonary bypass and 64 did.

RESULTS

In the control group there were increases (p < 0.01) in myoglobin and creatine kinase MB isoenzyme but no increase in cardiac troponin T or I; by contrast, the group treated with cardiopulmonary bypass had significant increases in all four markers but with differing temporal patterns. Younger age (especially < 12 months) was a highly significant explanatory variable only for the release of cardiac troponins T and I, and ischemic time was a significant explanatory variable for the release of creatine kinase MB isoenzyme, cardiac troponins T and I, but not myoglobin. In comparison with previous studies in adults, creatine kinase MB and cardiac troponin T concentrations were three times greater in children than in adults.

CONCLUSIONS

This study supports the specificity of cardiac troponins T and I as markers of myocardial injury after pediatric cardiac operations and defines the importance of age and ischemic time in determining their release. In comparison with previous data in adults, our results raise the possibility that the pediatric heart may be more vulnerable to the effects of ischemia and reperfusion. Cardiac troponins will permit comparison of new myocardial protective strategies or other potentially therapeutic myocardial interventions.

Excretion of ciprofloxacin in sweat and multiresistant Staphylococcus epidermidis

BACKGROUND

Staphylococcus epidermidis develops resistance to ciprofloxacin rapidly. That this antibiotic is excreted in apocrine and eccrine sweat of healthy individuals might be the reason for the development of such resistance. We assessed whether S epidermidis isolated from the axilla and nasal flora of healthy people could develop resistance to ciprofloxacin after a 1-week course of this antibiotic.

METHODS

The concentration of ciprofloxacin in sweat was measured in seven volunteers after oral administration of 750 mg ciprofloxacin twice daily for 7 days, and the development of resistance in S epidermidis from axilla and nostrils was monitored during and 2 months after the treatment. Genotyping of S epidermidis was done by restriction fragment length polymorphism.

FINDINGS

The mean concentration of ciprofloxacin in sweat increased during the 7 days of treatment-from 2.2 micrograms/mL 2.5 h after the first tablet to 2.5 micrograms/mL after the fifth tablet, and 5.5 micrograms/mL after the 13th tablet. All persons harboured susceptible S epidermidis (minimal inhibitory concentration [MIC] 0.25 microgram/mL) in axilla and nostrils before treatment. Four resistant strains were detected, two intermediate-level (MIC 4-12 micrograms/mL) and two high-level (MIC > 32 micrograms/mL). Three of these strains were found in all the participants, and a ciprofloxacin-sensitive variant of one of the high-level resistant strains was also found before the start of the treatment. The high-level resistant strains were also resistant to methicillin, erythromycin, gentamicin, sulphonamide, and trimethoprim. A mean of 2.7 days after the start of the treatment, development of ciprofloxacin resistance was detected in S epidermidis from the axilla of all persons, compared with 11 days for the appearance of resistant S epidermidis in nostrils. The resistant strains persisted for an average of 37 and 39 days in axilla and nostrils, respectively, after the end of the treatment.

INTERPRETATION

The rapid development of resistance to ciprofloxacin due to excretion of this drug into the sweat might be involved in the development of multiresistant S epidermidis and possibly other skin bacteria in hospitals and in communities with high use of ciprofloxacin or related drugs.

Regulator and effector functions of T-cell subsets in human Leishmania infections

Because of an increasing number of patients suffering from Leishmania infections and because of the serious consequences of these infections more thorough knowledge of the host factors responsible for resistance and susceptibility to the diseases is needed. In murine models of Leishmania infections the cytokine production by CD4+ T cells has been identified as a major factor in determining the outcome of the infection. In these models Th1 cells producing IFN-gamma provide protection against the infection whereas Th2 cells producing IL-4 and IL-10 aggravate the disease. The fatal outcome of Leishmania infections in humans with defects in T-cell functions illustrates that these cells are fundamental in the defence against Leishmania in humans also. However, as for many other infectious diseases (meningococcal disease and other septicaemic conditions, pneumonia, viral hepatitis, schistosomiasis) the immune reactions to Leishmania parasites in humans can be associated with both protection and pathogenesis. Many individuals without previous exposure to Leishmania parasites have T cells which can respond to Leishmania antigens. These cells have the potential to generate either Th1 or Th2 like responses. During infection with Leishmania parasites humans develop specific T-cell recognition of well-characterized parasite antigens. T cells producing disease-exacerbating factors such as IL-4 in response to Leishmania antigen stimulation have been identified in humans as well as in mice. Both Th1 like and Th2 like cells recognizing Leishmania antigens can be expanded during infection. At the polyclonal level Th1 like responses to Leishmania antigens are found in individuals who have had self-healing or asymptomatic infections. Factors secreted by such Leishmania specific Th1 like cells can induce killing of intracellular parasites in infected macrophages. In individuals who have been cured from uncontrollable disseminating disease both Th1 and Th2 like responses can be detected. A restriction in the antigen recognition to particular protein fractions could not be demonstrated in the Th1 or Th2 like responses. These findings suggest an association between the pattern of cytokines produced by parasite specific T cells and the clinical course of the infection similar to the one seen in mice. In the murine model the cytokine pattern present in the animal at the time of infection can determine whether a Th1- or a Th2 response will develop. In vitro studies on human and murine cells have confirmed that certain cytokines (e.g. IFN-gamma, IL-12) will favour maturation of Th1 responses whereas others (e.g. IL-4, IL-10) support Th2 development. If similar immunoregulatory mechanisms operate in mouse and man, design of vaccines against human leishmaniasis should aim at introducing powerful Th1 like responses. Importantly, once generation of either Th1 or Th2 has started, the immune response seems to be locked in this pattern, even when it is harmful to the host. Therefore new vaccines against leishmaniasis should be designed in a way that they generate controlled Th1 like primary responses.

Serodiagnosis of cutaneous leishmaniasis: assessment of an enzyme-linked immunosorbent assay using a peptide sequence from gene B protein

An enzyme-linked immunosorbent assay (ELISA) using a 28 amino acid sequence of the repetitive element of gene B protein (GBP) from Leishmania major was developed for serodiagnosis of cutaneous leishmaniasis (CL). The assay was compared to ELISAs using crude amastigote and promastigote antigens from L. donovani and the major surface glycoprotein (Gp63) from either L. donovani or L. major as a solid-phase ligand. The sensitivity of the assays was tested in 33 patients suffering from CL caused by L. major. The sensitivity of the GBP peptide (GBPP) ELISA was 82%. This was higher than in the assays using crude amastigote (67%) or promastigote (67%) antigens, but the difference was not statistically significant. The sensitivity in the assays using Gp63 from L. donovani (52%) or L. major (39%) was significantly lower than in the assay using GBPP (P = 0.019 and P < 0.001, respectively). Plasma samples from healthy Sudanese individuals living in an area endemic for malaria but free of leish-maniasis were negative in all the assays. Significantly higher levels of antibodies were found in the patients who had suffered from the disease for more than eight weeks than in patients with a shorter clinical history (GBPP ELISA; P = 0.038; amastigote ELISA; P = 0.004; and promastigote ELISA; P = 0.017). In the former group, the sensitivities of the five ELISAs were 100% (GBPP), 87% (amastigote), 93% (promastigote), 67% (L. donovani), and 53% (L. major), respectively.

Vulnerability of paediatric myocardium to cardiac surgery

OBJECTIVE

Myocardial injury is an important cause of mortality and morbidity after paediatric cardiac surgery. Data obtained from studies in animals imply that juvenile myocardium is more resistant to the effects of ischaemia and reperfusion than adult myocardium but there is little confirmatory evidence in the clinical setting.

DESIGN

Prospective observational study of biochemical markers of myocardial injury in a paediatric population undergoing cardiac surgery.

SETTING

Tertiary referral centre for paediatric cardiac surgery.

PATIENTS

Forty patients undergoing paediatric cardiac surgery of varying complexity including closure of atrial and ventricular septal defects and arterial switch for simple transposition. A control group included patients undergoing thoracotomy for closure of a patent ductus arteriosus or repair of a coarctation.

INTERVENTIONS

Serial measurements of myoglobin, the MB isoenzyme of creatine kinase (CK-MB), and the highly specific markers of myocardial damage cardiac troponin T (cTnT) and I (cTnI) were made before and 1, 6, 24, and 48 to 72 hours after operation.

RESULTS

There were significant increases in myoglobin and CK-MB, but not cTnT or cTnI, in the control group. There were significant increases in the four biochemical markers in all the cardiac operations but especially in the ventricular septal defect and transposition group. Increases in CK-MB and cTnT were about five times greater than those previously reported in adult patients.

CONCLUSIONS

(i) Cardiac troponins are more specific markers of myocardial injury in paediatric cardiac surgery than myoglobin and CK-MB. (ii) Paediatric myocardium seems to be more vulnerable to injury during cardiac surgery than adult myocardium.

Effects of short-term supplementation with coenzyme Q10 on myocardial protection during cardiac operations

BACKGROUND

Coenzyme Q10 (CoQ10) is a naturally occurring vitamin-like substance that may have a beneficial role in ischemia-reperfusion injury. Coenzyme Q10 administered either as an additive to cardioplegia or as long-term preoperative oral supplementation has been reported to ameliorate myocardial injury after cardiac operations.

METHODS

To determine whether short-term supplementation with large doses of CoQ10 (600 mg in divided doses 12 hours before operation) was effective in myocardial protection, 20 patients with well-preserved left ventricular function (ejection fraction greater than 0.50) undergoing elective coronary revascularization were enrolled in a prospective, double-blind, placebo-controlled randomized trial. Serial concentrations of CoQ10, myoglobin, creatine kinase MD fraction, and cardiac troponin T were measured preoperatively and 1, 6, 24, 72, and 120 hours postoperatively. Efficacy of myocardial protection was also assessed by clinical outcome and serial changes in electrocardiographic indices.

RESULTS

The patient groups were similar with respect to preoperative and intraoperative characteristics. There was no significant difference in the preoperative plasma levels of CoQ10. These levels fell significantly in both groups after operation, although the magnitude of the decrease was less in the CoQ10-supplemented group (43% versus 60%). In both groups, there were significant postoperative increases in myoglobin, creatine kinase MB fraction, and cardiac troponin T. The magnitude of increases in cardiac troponin T was greater in the CoQ10-supplemented group, reaching marginal overall statistical significance (p = 0.06).

CONCLUSIONS

Short-term supplementation with large doses of CoQ10 does not lead to improved myocardial protection in patients undergoing coronary revascularization with well-preserved ventricular function and relatively short ischemic times.