Lipid selectivity in novel antimicrobial peptides: Implication on antimicrobial and hemolytic activity.

Antimicrobial peptides (AMPs) are small cationic molecules that display antimicrobial activity against a wide range of bacteria, fungi and viruses. For an AMP to be considered as a therapeutic option, it must have not only potent antibacterial properties but also low hemolytic and cytotoxic activities [1]. Even though many studies have been conducted in order to correlate the antimicrobial activity with affinity toward model lipid membranes, the use of these membranes to explain cytotoxic effects (especially hemolysis) has been less explored. In this context, we studied lipid selectivity in two related novel AMPs, peptide 6 (P6) and peptide 6.2 (P6.2). Each peptide was designed from a previously reported AMP, and specific amino acid replacements were performed in an attempt to shift their hydrophobic moment or net charge. P6 showed no antimicrobial activity and high hemolytic activity, and P6.2 exhibited good antibacterial and low hemolytic activity. Using both peptides as a model we correlated the affinity toward membranes of different lipid composition and the antimicrobial and hemolytic activities. Our results from surface pressure and zeta potential assays showed that P6.2 exhibited a higher affinity and faster binding kinetic toward PG-containing membranes, while P6 showed this behavior for pure PC membranes. The final position and structure of P6.2 into the membrane showed an alpha-helix conversion, resulting in a parallel alignment with the Trps inserted into the membrane. On the other hand, the inability of P6 to adopt an amphipathic structure, plus its lower affinity toward PG-containing membranes seem to explain its poor antimicrobial activity. Regarding erythrocyte interactions, P6 showed the highest affinity toward erythrocyte membranes, resulting in an increased hemolytic activity. Overall, our data led us to conclude that affinity toward negatively charged lipids instead of zwitterionic ones seems to be a key factor that drives from hemolytic to antimicrobial activity.

Frequency, clinical features and prognosis of cutaneous manifestations in adult patients with reactive haemophagocytic syndrome.

BACKGROUND: Cutaneous involvement has been reported in 30-40% of children with the familial form of haemophagocytic syndrome. However, few studies have focused on cutaneous manifestations in patients with reactive haemophagocytic syndrome (RHS). OBJECTIVES: To describe the frequency, clinical features and prognosis of skin involvement in adult patients with RHS. METHODS: We conducted a retrospective study in a French university-based tertiary centre. The medical records of all adult patients with a suspected or confirmed diagnosis of RHS during a 2-year period were reviewed. Demographic, clinical, biological and histological data of patients were compared using nonparametric tests. RESULTS: The medical charts of 151 patients were reviewed, 69 of whom had a definite diagnosis of RHS (35% women; mean +/- SD age 49 +/- 17 years). The aetiology of RHS was mainly B-cell or T-cell lymphoma (n = 33) or herpesvirus infection (n = 19). Cutaneous manifestations were observed in 32 (46%) patients and were of three types: (i) specific to the underlying malignancy (Kaposi sarcoma n = 8, cutaneous lymphoma n = 4), (ii) reflecting the biological consequences of RHS (thrombopenic purpura n = 10, conjunctival jaundice n = 7), and (iii) a generalized, transient, nonpruriginous maculopapular rash (n = 18). None presented with erythroderma, or with eczematiform, ichthyosiform, psoriasiform or bullous lesions. One patient had cytophagic histiocytic panniculitis. Histological features of maculopapular rash biopsies were usually nonspecific. The rate of in-hospital death was not significantly associated with cutaneous involvement. CONCLUSIONS: A generalized, nonpruriginous, transient, maculopapular rash is frequently observed in patients with RHS. Although nonspecific, awareness of this cutaneous involvement may assist physicians in the initial diagnosis of RHS.

Varicella-zoster viral meningitis mimicking lymphoma.

We report the case of a 30-year-old HIV-infected man admitted for a meningeal syndrome and a zoster rash. The CSF had cytological features suggesting a primary CNS lymphoma (PCNSL). The large lymphoid cells had a fine chromatin with nucleoli, a basophilic cytoplasm with azurophilic granules and high mitotic activity. Several arguments demonstrated the viral origin of the meningitis: the large lymphoid cells were of T origin with no evidence of clonal TCR gamma gene rearrangement. The PCR was positive for Varicella-Zoster Virus (VZV) and EBV DNA. Clinical evolution was favorable under acyclovir. We should be cautious in the differential diagnosis between viral meningitis and PCNSL.

Diagnostic value of a nested polymerase chain reaction assay on peripheral blood mononuclear cells from patients with pulmonary and extra-pulmonary tuberculosis.

SETTING: Saint Louis Hospital, Paris, France. OBJECTIVE: To determine the clinical relevance of detection of Mycobacterium tuberculosis DNA by nested polymerase chain reaction (PCR) in peripheral blood mononuclear cells (PBMCs) in the rapid diagnosis of tuberculosis. DESIGN: Single-centre prospective case study of 90 hospitalised patients and 50 healthy subjects or blood donors from 1 January to 30 June 1998. RESULTS: Twenty-three patients were diagnosed with tuberculosis (26.7%); 20 tuberculosis patients were culture-positive, with seven smear-positive for acid-fast bacilli. Sensitivity of smear, culture and nested PCR was 30.4 (7/23), 87 (20/23) and 30.4% (7/23), respectively. The specificity of smear and culture was 100%, and the specificity of the nested PCR was 96% in the healthy subjects. However, the specificity decreased to 83.6% in the hospitalised patients, with 11 nested PCR-positive patients without a diagnosis of tuberculosis. The sensitivity of the nested PCR was low in pulmonary tuberculosis (22.2%), but increased in pulmonary/extra-pulmonary tuberculosis (50%), extra-pulmonary tuberculosis (33%), and disseminated tuberculosis (33%). CONCLUSION: The use of a nested PCR assay on PBMC may pose problems for the rapid diagnosis of tuberculosis with regard to low sensitivity and specificity. However, further studies are needed to confirm this technique as an alternative test for the diagnosis of paucibacillary forms of tuberculosis.

Haemophagocytic syndrome associated with plasmodium vivax infection.

A 41-year-old woman was admitted with fever, splenomegaly and pancytopenia. High serum ferritin, hypertriglyceridaemia and bone marrow haemophagocytosis were consistent with a haemophagocytic syndrome. Trophozoites and gametocytes of Plasmodium vivax were identified on blood smear. Rapid recovery was observed after treatment with oral chloroquine.

Deregulated expression of promyelocytic leukemia zinc finger protein in B-cell chronic lymphocytic leukemias does not affect cyclin A expression.

INTRODUCTION: The promyelocytic leukemia zinc finger (PLZF) gene encodes a transcription factor expressed in myeloid, lymphoid and CD34(+) progenitor cells. Structurally related to BCL-6, which is involved in human lymphoma, PLZF may have a role in proliferation, differentiation and survival of hematopoietic cells, that could be mediated by transcriptional repression of the cyclin A gene. MATERIALS AND METHODS: Quantitative competitive reverse transcription-polymerase chain reaction was used to measure the levels of expression of PLZF and cyclin A in normal leukocyte subsets (including CD19(+) lymphocytes, n=21) and malignant B lymphocytes (including B-chronic lymphocytic leukemias [B-CLL], n=63). Results obtained with this method were confirmed by Western and Northern blot analysis. Transactivation assays were performed using an expression construct for PLZF and two cyclin A promoter luciferase reporters in an Epstein-Barr virus (EBV)-transformed B-cell line. Cyclin A expression, cell growth kinetics, and cell cycle were analysed in stable clones of the Burkitt lymphoma (BL) B-cell line DG75 with inducible expression of PLZF, generated using the tetracycline-regulated expression system. RESULTS: Expression of PLZF was 100-fold downregulated in 90% B-CLL (56/63) compared to normal B lymphocytes (P<0.001). B-CLL patients with the highest levels of PLZF had a poorer survival (P<0.013). In transactivation assays, PLZF inhibited the activity of the cyclin A reporters by 50%, demonstrating that PLZF can repress cyclin A expression in non-malignant B lymphocytes. However, in B-CLL patients, the level of cyclin A expression was found to be within the normal range. Altered PLZF function in B lymphoid malignancies was further corroborated in the PLZF-regulatable DG75 clones, where induction of PLZF expression did not significantly alter the levels of cyclin A expression, the cell growth kinetics, or the cell cycle phase distribution. CONCLUSION: The lower survival of patients with the highest levels of PLZF suggests that this protein may be a marker of progression in B-CLL. The absence of co-ordinated regulation of PLZF and cyclin A genes in B-CLL and in a malignant B-cell line may indicate a loss of cyclin A control by PLZF in B-CLL and other B-cell disorders. Deregulation of PLZF could thus play a role in B-cell malignancy.

Aplastic anemia and paroxysmal nocturnal hemoglobinuria: a follow-up study of the glycosylphosphatidylinositol-anchored proteins defect.

INTRODUCTION: Flow cytometry analysis of peripheral blood cells is a simple and reliable method for establishing the diagnosis of paroxysmal nocturnal hemoglobinuria. The behavior of the clone may vary; increasing or diminishing over time but prospective study of such variations have not been reported so far. MATERIALS AND METHODS: We report herein the results of a prospective follow-up study of 25 patients. Our aims were twofold: first, to evaluate the behavior of the clone (using flow cytometry) over the time; and second, to evaluate if such variations could predict the occurrence of complications or could be used as a tool for monitoring the residual disease after bone marrow transplantation. RESULTS: It was found that flow cytometry can be used to specifically follow the residual disease post allogeneic marrow transplantation in four patients, and that even without transplantation the defective clone can significantly decrease or even disappear (three patients). CONCLUSION: We found that most of the patients did have significant change in the amount of affected cells during more than three years, and that an increased size of the clone poorly predicted the occurrence of complications.

Aplastic anaemia in a case of hereditary neutrophil Fcgamma receptor IIIb deficiency.

CD16 antibodies recognize Fcgamma receptors III of a and b types. In a patient with severe idiopathic aplastic anaemia (AA), polymorphonuclear cells, which in normal subjects express FcgammaRIIIb, were found to be CD16 negative. The FcgammaRIIIb gene configuration was analysed by PCR on peripheral blood mononuclear cells. Bi-allelic deletion encompassing at least part of the coding exon 5 was found in the patient and his brother, suggesting a hereditary defect. The patient underwent successful bone marrow transplantation from his HLA-matched brother despite a similar phenotype and genotype. This observation suggests that FcgammaRIIIb hereditary deficiency in donor and/or recipient does not impair engraftment and justifies the use of other monoclonal antibodies in addition to CD16 in the study of GPI-anchored antigen expression.

Prognostic significance of chromosomal abnormalities in acute nonlymphocytic leukemia: a study of 343 patients.

Clonal chromosome abnormalities of 343 patients with de novo acute nonlymphocytic leukemia (ANLL) have been tentatively correlated with prognosis. All the patients were treated according to therapeutic protocols in the same hospital. The complete remission rate and median survival were generally lower in AA-ANLL (ANLL with only karyotypically abnormal metaphases) when compared with NN- and AN-ANLL. Similarly, AA-ANLL had the poorest prognosis in the majority of the classes of the French-American-British nomenclature. ANLL with inversion and/or deletion of chromosome #16 had the best prognosis, and ANLL with t(8;21) was not particularly favorable, nor was acute promyelocytic leukemia with t(15;17). ANLL with complex chromosomal abnormalities had the poorest prognosis. The conclusion is that chromosomal aberrations do have a prognostic significance in ANLL, but that this significance is dependent on the types of chromosomal aberrations.