Colonisation by Faecalibacterium prausnitzii and maintenance of clinical remission in patients with ulcerative colitis

BACKGROUND

Although incrimination of the intestinal microbiota in the pathogenesis of IBD is widely accepted, few data are available about the role of specific bacteria. Potentially, Faecalibacterium prausnitzii, bacteria with anti-inflammatory properties, might be deficient in ulcerative colitis (UC).

AIM

To quantify F. prausnitzii in the faecal microbiota of UC patients in remission and determine its relationship with relapse.

METHODS

A cross-sectional study included 116 UC patients in remission, 29 first-degree relatives and 31 healthy controls. A subset of eighteen patients, recruited during the first month of remission, underwent a 1-year follow-up. Total bacteria and F. prausnitzii were measured by quantitative Real Time PCR (qPCR, copies/g). Calprotectin was determined as inflammatory index (μg/g).

RESULTS

We found that F. prausnitzii was reduced in patients (median, IQR: 1.4 × 10⁸ , 5.1 × 10⁷-4.5 × 10⁸) and relatives (1.7 × 10⁸, 9.3 × 10⁷-5.1 × 10⁸) vs. controls (6.5 × 10⁸, 3.7 × 10⁸-1.6 × 10⁹, P < 0.0001). Moreover, low counts of F. prausnitzii were associated with less than 12 months of remission (8.0 × 10⁷, 2.0 × 10⁷-3.5 × 10⁸ vs. 2.1 × 10⁸, 1.0 × 10⁸-7.9 × 10⁸, P < 0.001) and more than 1 relapse/year (8.0 × 10⁷, 3.2 × 10⁷-3.8 × 10⁸ vs. 1.9 × 10⁸, 6.8 × 10⁷-6.0 × 10⁸, P < 0.01). When patients were followed up, F. prausnitzii increased steadily until reaching similar levels to those of controls if remission persisted (2.9 × 10⁸, 9.3 × 10⁶-1.2 × 10⁹; calprotectin: 76, 19-212), whereas it remained low if patients relapsed (2.2 × 10⁸, 1.4 × 10⁶-3.3 × 10⁸; calprotectin: 1760, 844-3662 P < 0.05 vs. controls).

CONCLUSIONS

Defective gut colonisation by F. prausnitzii occurred in UC patients during remission and in their unaffected relatives. The recovery of the F. prausnitzii population after relapse is associated with maintenance of clinical remission.

Acute experimental stress evokes a differential gender-determined increase in human intestinal macromolecular permeability

BACKGROUND

Intestinal epithelial dysfunction is a common pathophysiologic feature in irritable bowel syndrome (IBS) patients and might be the link to its clinical manifestations. We previously showed that chronic psychosocial stress induces jejunal epithelial barrier dysfunction; however, whether this epithelial response is gender-specific and might thus explain the enhanced female susceptibility to IBS remains unknown.

METHODS

Intestinal responses to acute stress were compared in age-matched groups of healthy women and men (n = 10 each) experiencing low background stress. A 20-cm jejunal segment, was perfused with an isosmotic solution, and intestinal effluents were collected under basal conditions, for 15 min during cold pain stress and for a 45-min recovery period. Epithelial function (net water flux and albumin output), changes in stress hormones, and cardiovascular and psychologic responses to cold stress were measured.

KEY RESULTS

Heart rate and blood pressure significantly increased during cold pain stress with no differences between men and women. Adrenocorticotropic hormone and cortisol levels during cold pain stress were significantly higher in men. Basal net water flux and epithelial permeability were similar in men and women. Cold pain stress increased water flux in both groups (72 ± 23 and 107 ± 18 μL min(-1) cm(-1) , respectively; F(5, 90) = 5.5; P = 0.003 for Time) and, interestingly, this was associated with a marked increase of albumin permeability in women but not in men (0.8 ± 0.2 vs.-0.7 ± 0.2 mg/15 min; P < 0.0001).

CONCLUSIONS & INFERENCES

Intestinal macromolecular permeability in response to acute experimental stress is increased in healthy women, a mechanism that may contribute to female oversusceptibility to IBS.

Recombination Dynamics in Nitride Quantum Boxes and Quantum Wells for Colors Ranging from the UV to the Red

Time-resolved photoluminescence experiments at varying temperature are performed on a series of InxGa1−xN/GaN quantum well and quantum box samples of similar compositions (0.15 < x < 0.20). The results are analyzed by using envelope-function calculations of transition energies and oscillator strengths, accounting for internal electric fields. The respective influences of localization and electric fields on radiative and nonradiative lifetimes and on the Stokes shift are deduced. The results indicate that the spatial extension of localization centers is much smaller than the size of the quantum boxes (∼10 × 3 nm, typically). The room-temperature radiative efficiency of both quantum well and quantum box samples is enhanced by replacing the topmost GaN barrier by an AlGaN one.

Immunophenotype of acute myeloid leukemia with NPM mutations: prognostic impact of the leukemic compartment size

NPM mutations are the most common genetic abnormalities found in non-promyelocytic AML. NPM-positive patients usually show a normal karyotype, a peculiar morphologic appearance with frequent monocytic traits and good prognosis in the absence of an associated FLT3 mutation. This report describes the immunophenotypic and genetic characteristics of a consecutive series of NPM-mutated de novo AML patients enroled in the CETLAM trial. Eighty-three patients were included in the study. Complete immunophenotype was obtained using multiparametric flow cytometry. Associated genetic lesions (FLT3, MLL, CEBPA and WT1 mutations) were studied by standardized methods. Real-time PCR was employed to assess the minimal residual status. The most common pattern was CD34-CD15+ and HLA-DR+. Small CD34 populations with immunophenotypic aberrations (CD15 and CD19 coexpression, abnormal SSC) were detected even in CD34 negative samples. Nearly all cases expressed CD33 (strong positivity), CD13 and CD117, and all were CD123+. The stem cell marker CD110 was also positive in most cases. Biologic parameters such as a high percentage of intermediate CD45+ (blast gate) (>75% nucleated cells), CD123+ and FLT3-ITD mutations were associated with a poor outcome. Quantitative PCR positivity had no prognostic impact either after induction or at the end of chemotherapy. Only PCR positivity (greater than 10 copies) detected in patients in haematological remission was associated with an increased relapse rate. Further studies are required to determine whether the degree of leukemic stem cell expansion (CD45+CD123+cells) increases the risk of acquisition of FLT3-ITD and/or provides selective advantages.

Prognostic value of minimal residual disease (MRD) in acute myeloid leukemia (AML) with favorable cytogenetics [t(8;21) and inv(16)]

Most patients with acute myeloid leukemia (AML) and t(8;21) or inv(16) have a good prognosis with current anthracycline- and cytarabine-based protocols. Tandem analysis with flow cytometry (FC) and real-time RT-PCR (RQ-PCR) was applied to 55 patients, 28 harboring a t(8;21) and 27 an inv(16), including one case with a novel CBFbeta/MYH11 transcript. A total of 31% (n=17) of CR patients relapsed: seven with t(8;21) and 10 with inv(16). The mean amount of minimal residual disease (MRD) detected by FC in relapsed and nonrelapsed patients was markedly different: 0.3 vs 0.08% (P=0.002) at the end of treatment. The mean number of fusion transcript copies/ ABL x 10(4) also differed between relapsed and non-relapsed patients: 2385 vs 122 (P=0.001) after induction, 56 vs 7.6 after intensification (P=0.0001) and 75 vs 3.3 (P=0.0001) at the end of chemotherapy. Relapses were more common in patients with FC MRD level >0.1% at the end of treatment than in patients with < or = 0.1%: cumulative incidence of relapse (CIR) was 67 and 21% (P=0.03), respectively. Likewise, using RQ-PCR, a cutoff level of >10 copies at the end of treatment correlated with a high risk of relapse: CIR was 75% for patients with RQ-PCR >10 compared to 21% for patients with RQ-PCR levels < or = 10 (P=0.04). Combined use of FC and RQ-PCR may improve MRD detection, and provide useful clinical information on relapse kinetics in AML patients.

Adverse prognostic impact of CD36 and CD2 expression in adult de novo acute myeloid leukemia patients

BACKGROUND AND OBJECTIVES

A consecutive series of acute myeloid leukemias (AML) patients was analyzed in conditions which reduce the inter-assay variations (the same flow cytometer, the same observers and the same panel of monoclonal antibodies) in order to investigate the prognostic information provided by flow cytometry.

DESIGN AND METHODS

Two hundred and sixty-six bone marrow (BM) samples from 326 patients enrolled in the LMA-99 protocol from the CETLAM group were studied by multiparametric flow cytometry. Immunophenotyping studies were performed on erythrocyte-lysed BM samples. Antigen expression of leukemic cells was analyzed using triple stainings with fluorochrome-conjugated combinations of monoclonal antibodies.

RESULTS

CD2 was positive in 21 cases (8%); an associated inv(16) was detected in eight CD2+ cases (38%). Two-year overall survival (OS) rate for CD2+/inv(16)+ patients was 75%, whereas it was 0% for CD2+/inv(16)- patients and 47% for CD2- patients (p=0.0001). CD36 was expressed in 37% of patients (n=98). Two-year leukemia-free survival (LFS) rate was 34% for CD36+ patients and 55% for CD36- patients (p=0.001). In the multivariate analysis, CD2+ (RR=8.4; p=0.0001) and adverse karyotype (RR=10.2; p=0.0001) were associated with a lower CR rate, CD36+ (RR=1.5; p=0.03), CD2+ (RR=2; p=0.04) and adverse karyotype (RR=4; p=0.0001) were associated with a lower OS and CD36+ (RR=2; p=0.002) and adverse karyotype (RR=3.5; p=0.005) predicted a lower LFS.

CONCLUSIONS

CD2+ patients had a very poor OS when CD2/inv(16)+ cases were excluded. CD36 and CD2 expression at diagnosis can provide prognostically important information in adult de novo AML.

Quantification of foetomaternal haemorrhage. An analysis of two cytometric techniques and a semiquantitative gel agglutination test

Traditional tests to screen for foetomaternal haemorrhage are time-consuming and difficult to perform. The Kleihauer test is widely used but difficult to standardize. We evaluated three techniques for quantifying foetomaternal haemorrhage: a semiquantitative gel agglutination test and two flow cytometric techniques. The gel agglutination test is based on the consumption of anti-D reagent by D+ cells, analysing the reaction of the supernatant against indicator cells in a Coombs-gel card. In the two colour direct immunofluorescent technique, the sample is incubated with Per-CP labelled anti CD45 antibody, fixed with glutaraldehyde and permeabilized by exposure to Triton X-100. An aliquot is stained with an antibody to foetal haemoglobin, conjugated with fluorescein isothiocyanate or phycoerythrin. The indirect immunofluorescent technique is based on the labelling of Rh (D) antigen with an anti D reagent, followed by the addition of an anti IgG antibody conjugated with phycoerythrin. Foetomaternal haemorrhage was not detected in 75 of the 85 samples analysed by the direct immunofluorescent technique. In the remaining 10 samples, the volume was very low. Thirty-five samples with Rh (D) antigen incompatibility were analysed in parallel by the indirect immunofluorescent technique and in 15 of the 35 samples, the gel agglutination technique was also carried out. The three techniques gave similar results. The gel agglutination test can be used to screen for foetomaternal haemorrhage, while greater volumes should be quantified by flow cytometric techniques.

[Familial study for the early diagnosis of insulin-dependent diabetes mellitus]

BACKGROUND

Diabetes is more frequently found than expected in families of first grade with children with diabetes type I.

METHODS

With the aim of identifying the potential candidates prone to develop diabetes type I, genetic and metabolic analysis was carried out on the members of 11 families with a diabetic type I child. They were distributed into three groups: 11 diabetic patients (IDDM); 22 progenitors and 13 unaffected siblings. The HLA haplotype was determined, the spectrum of autoantibodies and the intravenous glucose tolerance test (IVTT) were performed.

RESULTS

In two progenitors postprandial glycemia values corresponding to intolerance to carbon hydrates were obtained. Moreover, in one the IVTT was found to be low in the normal values. Of a total of 12 non diabetic descendents studied, 4 shared identical HLA haplotypes as the diabetic, 5 were haploidentical and 3 unidentical. The DR 3 antigen was detected in 90% of the diabetics; in 68% of the progenitor group and in 50% of the non diabetic descendents. Sixty-two percent of the children inherited the DR 4 antigen of the father (p less than 0.05), while 37% do so from the mother. Of the siblings with a haplotype identical to that of the diabetic, 2 were also ICA positive; asymptomatic at the moment of the study but in one the diabetes type I became manifest after 2 years of evolution.

CONCLUSIONS

Subjects at high risk of becoming type I diabetics may be identified at a preclinical phase by means of HLA typing and the detection of immunologic and metabolic markers associated with the disease.

[Posttransfusion thrombocytopenic purpura. 1st case described in Spain]

Following a total blood transfusion, a 65 year old woman suffered severe thrombocytopenia characterized by purpura and haemorrhage. An immunological study revealed the existence of IgG and IgM type antibodies in the serum attached to the patient's platelets and to the eluate obtained from these. The specificity of the antibody was Zwa. The patient's platelets are Zwa-negative. Even in the remission phase of the thrombocytopenia it was still possible to obtain antibodies in the platelets of the eluate. Questions raised by this factor are discussed and, despite the difficulties posed, an attempt is made to find a coherent immunological explanation based on the results of the serological study.