Role of NK cells and gamma interferon in transplacental passage of Toxoplasma gondii in a mouse model of primary infection

Protective immunity in mice infected with Toxoplasma gondii is mainly mediated by NK cells, CD4 and CD8 T cells, and type 1 cytokines, such as gamma interferon (IFN-gamma). To clarify the roles of NK cells and IFN-gamma in protection against primary congenital toxoplasmosis, we used recombination activating gene 2 knockout (RAG-2(-/-)) mice, which lack T and B lymphocytes, in comparison with the wild-type BALB/c model. RAG-2(-/-) mice had a significantly lower risk of fetal toxoplasmosis than BALB/c mice (25 versus 63.9%; P = 0.003). This protection was associated with an increased number of maternal NK cells, IFN-gamma secretion by spleen cells, and decreased parasitemia. In the RAG-2(-/-) mice, NK cell depletion increased both the rate of fetal infection, to 56.5% (P = 0.02), and the blood parasite burden. Conversely, in the BALB/c mice, this treatment did not modify maternofetal transmission or the blood parasite burden. Neutralization of IFN-gamma in both infected RAG-2(-/-) and BALB/c mice decreased congenital Toxoplasma transmission, contrasting with an exacerbation of maternal infection. These data suggest that a partially protective immunity against congenital toxoplasmosis is achieved due to the increased number of NK cells in RAG-2(-/-) mice. However, it seems that IFN-gamma enhances, directly or indirectly, the transplacental transmission.     

European seroepidemiology network 2: Standardisation of assays for seroepidemiology of varicella zoster virus.

BACKGROUND: The aim of the European Sero-Epidemiology Network (ESEN2) is to harmonise the serological surveillance of vaccine-preventable diseases in Europe. OBJECTIVE: To allow comparison of antibody prevalence in different countries by standardising results into common units. STUDY DESIGN: For varicella zoster virus (VZV), a reference laboratory established a panel of 148 samples, characterised by indirect enzyme-immunoassay (ELISA), indirect immunofluorescence, and complement fixation test. Fifty-seven samples were also studied by the fluorescence antibody to membrane antigen test. The geometric mean of the antibody activity (GMAA) obtained from four ELISA determinations was used to characterise each sample of the panel as positive (GMAA: >100 mIU/ml), equivocal (GMAA: 50-100 mIU/ml) or negative (GMAA: <50 mIU/ml) for antibody to VZV (anti-VZV). Thirteen laboratories, using five different ELISA tests, tested the panel. RESULTS: Agreement with the reference laboratory was above 85% in all cases, and the R(2) values obtained from regression analysis of the quantitative results were always higher than 0.87. Finally, the regression equations could be used to convert national values into a common unitage. CONCLUSION: This study confirmed that results for anti-VZV obtained by different ELISA methods can be converted into common units, enabling the comparison of the seroprevalence profiles obtained in the participant countries.     

Evaluation of serum chemistry values associated with avian malaria infections in African black-footed penguins (Spheniscus demersus)

The value profiles of 5 intracellular enzymes, 15 metabolites (with 2 associated ratios), and 3 electrolytes were monitored over time in 9 captive-reared African black-footed penguins (Spheniscus demersus) with different avian malaria clinical status: uninfected, subclinically infected, and clinically infected with fatal outcome. Fatal infections were caused byPlasmodium relictum. Numerous schizonts were visible in the lungs, liver, spleen, and interstitial tissue of the kidneys. The feference ranges of 23 serum clinical chemistry parameters and 2 ratios were established forS. demersus. The mean values obtained for 8 of 23 parameters of the infected penguins were signficantly different from those recorded for the uninfected birds, indicating impaired renal function, hepatic dysfunction, and nonspecific tissue damage related to the infestation with exoerythrocytic schizonts. Analysis of sensitivity, specificity, and negative and positive predictive values (PPVs) showed that gamma-glutamyltranspeptidase (GGTP), alanine aminotransferase (ALT), and creatinine reached PPVs and a specificity over 57% for avian malaria infections in penguins. Creatinine, ALT, and GGTP values should be consulted in evaluation of the clinical malaria status ofS. demersus.     

Growth hormone improves lean body mass, physical performance, and quality of life in subjects with HIV-associated weight loss or wasting on highly active antiretroviral therapy

HIV-associated wasting is defined as > or = 10% involuntary weight loss and includes declines in both lean and fat mass. This large (757 subjects), randomized, double-blind, placebo-controlled trial investigated the efficacy, safety, and tolerability of recombinant human growth hormone (rhGH) in 2 doses-0.1 mg/kg up to a maximum of 6 mg daily (DD) or alternate days (AD)-in the treatment of wasting and weight loss in highly active antiretroviral therapy (HAART)-treated HIV-infected subjects. The evaluable population for ergometry comprised 555 subjects, 87.6% of whom were receiving HAART. At 12 weeks, median maximum work output increased by 2.4 and 2.6 kJ in the AD and DD groups, respectively. The median treatment difference was 2.9 kJ for DD vs. placebo (P < 0.0001). Body weight increased by 2.2 and 2.9 kg in the AD and DD groups, respectively. Corresponding median treatment differences vs. placebo were 1.5 and 2.2 kg (P < 0.0001). Lean body mass (LBM), by bioelectric impedance spectroscopy, increased by 3.3 and 5.2 kg, respectively (P < 0.0001 vs. placebo; P = 0.0173 DD vs. AD), and fat mass, predominately truncal, decreased. Quality of life (QoL) improved significantly in both rhGH groups. Fluid-retention adverse effects and hyperglycemia were more common in the DD than in the AD group. No significant changes in HIV viral load or CD4 cell count occurred. In conclusion, over the 12-week course of therapy, rhGH, 0.1 mg/kg DD, was superior to placebo in improving physical function, body weight, body composition, and QoL and was superior to AD dosing in restoring LBM.     

Trisomy 7 mosaicism, maternal uniparental heterodisomy 7 and Hirschsprung's disease in a child with Silver-Russell syndrome

Prenatal trisomy 7 is usually a cell culture artifact in amniocytes with normal diploid karyotype at birth and normal fetal outcome. In the same way, true prenatal trisomy 7 mosaicism usually results in a normal child except when trisomic cells persist after birth or when trisomy rescue leads to maternal uniparental disomy, which is responsible for 5.5-7% of patients with Silver-Russell syndrome (SRS). We report here on the unusual association of SRS and Hirschsprung's disease (HSCR) in a patient with maternal uniparental heterodisomy 7 and trisomy 7 mosaicism in intestine and skin fibroblasts. HSCR may be fortuitous given its frequency, multifactorial inheritance and genetic heterogeneity. However, the presence of the trisomy 7 mosaicism in intestine as well as in skin fibroblasts suggests that SRS and HSCR might possibly be related. Such an association might result from either an increased dosage of a nonimprinted gene due to trisomy 7 mosaicism in skin fibroblasts (leading to SRS) and in intestine (leading to HSCR), or from an overexpression, through genomic imprinting, of maternally expressed imprinted allele(s) in skin fibroblasts and intestine or from a combination of trisomy 7 mosaicism and genomic imprinting. This report suggests that the SRS phenotype observed in maternal uniparental disomy 7 (mUPD(7)) patients might also result from an undetected low level of trisomy 7 mosaicism. In order to validate this hypothesis, we propose to perform a conventional and molecular cytogenetic analysis in different tissues every time mUPD7 is displayed.     

Isodicentric/pseudoisodicentric chromosome 21 amplification in four cases of acute myelocytic leukemia or myelodysplasia

The bone marrow karyotypes of three patients with acute myelocytic leukemia (AML) or myelodysplastic syndrome (MDS) were studied at diagnosis and revealed, multiple copies of the same chromosomal anomaly, considered as psu idic(21)(q22) associated with other rearrangement(s). The karyotype of a fourth patient with MDS in transformation showed one copy of a dicentric marker presumably derived from a similar psu idic(21) by (tandem?) interstitial amplification of part of its structure, resembling a "homogeneous staining region", and described as der(21)psu idic(21)(q22)hsr(21)(q22). This rearrangement, previously described in isolated cases only, might be considered as recurrent in AML/MDS and associated with an unfavorable prognosis. It is most probably a secondary change, because it was never observed as sole abnormality and the main association, as for trisomy 21, was with del(5q). In the four cases, the number of partial supernumerary segmental 21pter-->21q22 copies, ranged from 2 to 10. The AML1 gene did not appear to be the common target of this amplification because this locus had been lost by the psu idic(21) in one patient     

Healthy monozygous twins do not recognize identical T cell epitopes on the myelin basic protein autoantigen

The T cell response against myelin basic protein (MBP) has been extensively studied in humans because of its putative role in the pathophysiology of multiple sclerosis (MS). Higher concordance rates in monozygous twins as well as an increased risk in relatives suggest the role of genetic factors in MS susceptibility. Very little is known about the shaping of T cell repertoire towards self antigens in humans and their contribution to disease susceptibility in autoimmune disorders. Here we report the comparative T cell epitope recognition patterns towards the MBP auto-antigen in healthy identical twins. We have established MBP-specific T cell lines from eight sets of twins and characterized their fine epitope specificity. Intra-pair comparison showed the co-existence of shared as well as distinct epitopes in six of eight pairs and a complete absence of concordant epitope recognition within two other pairs. These findings indicate that important differences in T cell repertoires against a self antigen may be observed between genetically identical healthy individuals, rendering difficult the interpretation of the differences which may be observed between identical twins discordant for an autoimmune disease.     

Immunohistological analysis of the lymphoid infiltrate in cutaneous malignant melanomas

Summary The immunological phenotypes of the lymphoid cells in 39 cutaneous malignant melanomas have been investigated by staining cryostat sections with a panel of 20 monoclonal antibodies against lymphoid cells and their subsets. Staining was performed by the alkaline phosphatase: anti-alkaline phosphatase (APAAP) method in which the substrate label (red) is easily distinguishable from melanin. The lymphoid infiltrates had an essentially identical composition in all cases, consisting of T-lymphocytes associated with both Langerhans cells and HLA-DR-positive tissue macrophages. B-lymphocytes and natural killer cells were either absent or only present in low numbers. The ratio between T8 (suppressor/cytotoxic) and T4 (helper/inducer) lymphocytes varied and showed no correlation with melanoma subtype, level of invasion or magnitude of lymphocytic response. Examination for markers associated with T-cell activation and/or with cell proliferation revealed that all lesions contained HLA-DR-positive T-lymphocytes, whereas expression of the transferrin receptor and the interleukin-2 receptor (Tac-antigen) occurred mainly in melanomas with a significant inflammatory infiltrate. These data support the concept that malignant melanomas are capable of evoking autologous T-cell immune reactions.     

Transmitter release at the hair cell ribbon synapse.

Neurotransmitters are released continuously at ribbon synapses in the retina and cochlea. Notably, a single ribbon synapse of inner hair cells provides the entire input to each cochlear afferent fiber. We investigated hair cell transmitter release in the postnatal rat cochlea by recording excitatory postsynaptic currents (EPSCs) from afferent boutons directly abutting the ribbon synapse. EPSCs were carried by rapidly gating AMPA receptors. EPSCs were clustered in time, indicating the possibility of coordinate release. Amplitude distributions of spontaneous EPSCs were highly skewed, peaking at 0.4 nS and ranging up to 20 times larger. Hair cell depolarization increased EPSC frequency up to 150 Hz without altering the amplitude distribution. We propose that the ribbon synapse operates by multivesicular release, possibly to achieve high-frequency transmission.     

Pathology of chronic constipation in pediatric and adult coloproctology.

In colonic motility disorders, a pathohistological diagnosis based solely on formalin-fixed gut is often inconclusive. Classical histological techniques or immunohistochemistry represent a static staining. In contrast, native tissue submitted to enzyme histochemistry provides functional information about the effectiveness of the cellular performance. Routinely, a complementary set of reactions is performed and includes acetylcholinesterase (AChE), lactic and succinic dehydrogenase, as well as nitroxide synthase reactions. In this monograph, the whole spectrum of different anomalies of the colonic wall is illustrated in a systematic fashion: Hirschsprung's disease is characterized by an increase in AChE activity of parasympathetic nerve fibers of the rectosigmoid. In ultrashort Hirschsprung's disease, only enzyme histochemistry renders a reliable diagnosis possible in biopsies of the anal ring. Aganglionosis of the musculus corrugator cutis ani shows a localized increase of AChE activity in nerve fibers, similar to Hirschsprung's disease, not detectable in conventional histology. Immaturity, hypoganglionosis and neuronal dysganglionosis can be clearly recognized in dehydrogenase reactions. Enzyme histochemical reactions are complemented by picrosirius red staining for assessment of the collagen texture of the muscularis propria. Absence or intertenial interruption of the continuous connective tissue layer between circular and longitudinal muscle of the muscularis propria has been termed aplastic or atrophic desmosis, respectively. Many of the entities described are also observed in adults. Atrophic hypoganglionosis or atrophic desmosis with loss of the myenteric plexus connective tissue fascia is implied as a frequent cause of chronic constipation in adults. The essential contribution of a functional histopathological technique towards a reliable diagnosis of gut dysfunction in native tissue is extensively demonstrated in great detail in more than two hundred figures.