Analytical and clinical evaluation of four commercial SARS-CoV-2 serological immunoassays in hospitalized patients and ambulatory individuals

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Hospitalized patients seroconverted at ≥ 3 weeks pso.

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Ambulatory symptomatic individuals seroconverted at 14 days pso.

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Illness’ severity degree and infection phase impacted the longitudinal Ab changes.

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Five “severe-to-critically” ill patients have positive Ab levels up to 16 weeks pso.

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Total Ab immunoassay, compared to IgG, present a better sensitivity and specificity.

Background

This study aimed to compare four anti-SARS-CoV-2 immunoassays in populations presenting different clinical severity levels.

Methods

Three populations were included: “severe-to-critical” ICU-hospitalized patients (n = 18), “mild-to-moderate” hospitalized patients (n = 16) and non-hospitalized symptomatic patients (n = 24). Four commercial immunoassays were analyzed and validated: anti-IgG ARCHITECT® (Abbott), anti-Total antibodies (Ab) VITROS® (Ortho Clinical Diagnostics), anti-IgG NovaLisa® (NovaTec Immundiagnostica) and Healgen® IgM and IgG (Zhejiang Orient Gene Biotech). Sensitivities were evaluated according to days post-symptoms onset (pso). Specificities were evaluated on SARS-CoV-2-negative control sera collected before January 2020.

Results

A majority of severe-to-critically ill patients showed detectable Ab already at day 14 and sensitivities reached 100 % after 22 days pso. For patients with “mild-to-moderate” illness, sensitivities increased by at least 5-fold from day 0 to day 14 pso. Non-hospitalized symptomatic individuals already seroconverted at day 14 days pso with 100 % sensitivities for Total Ab VITROS®. Specificities were evaluated at 97 % for ARCHITECT® and NovaLisa®, 98 % for VITROS® and at 94 % for Healgen® combined IgM and IgG. Five “severe-to-critically” ill patients presented high positive Ab levels for at least 16 weeks pso.

Conclusion

The Ab levels and the evaluated sensitivities, representing the true positive rate, increased overtime and were related to the COVID-19 severity. Automated Total Ab immunoassay showed better sensitivities and specificity for immunological surveillance and vaccine evaluation.

Semiconductor Quantum Plasmonics

We investigate the frontier between classical and quantum plasmonics in highly doped semiconductor layers. The choice of a semiconductor platform instead of metals for our study permits an accurate description of the quantum nature of the electrons constituting the plasmonic response, which is a crucial requirement for quantum plasmonics. Our quantum model allows us to calculate the collective plasmonic resonances from the electronic states determined by an arbitrary one-dimensional potential. Our approach is corroborated with experimental spectra, realized on a single quantum well, in which higher order longitudinal plasmonic modes are present. We demonstrate that their energy depends on the plasma energy, as is also the case for metals, but also on the size confinement of the constituent electrons. This work opens the way toward the applicability of quantum engineering techniques for semiconductor plasmonics.

Abstract 4123: CRISPR-Cas9 and siRNA screening in primary human immune cells

A major focus in immuno-oncology research is finding new immuno-oncology targets, including those that alter the character and frequency of T-cell-mediated anti-tumour responses. Screens using CRISPR (Clustered Regularly Interspaced Short Palindromic Repeats)-Cas9-mediated genome editing seem well placed to identify new targets. However, although CRISPR-Cas9 gene editing works well in primary T cells using electroporation, use of a lentivirus one vector system has proved challenging in primary T cells compared with cancer cell lines. We have used several different approaches to identify the most useful method for transduction of primary human T cells with CRISPR components. Electroporation of sgRNAs and mRNA encoding Cas9 into proliferating T cells efficiently generate T cells with specific gene knock-outs or knock-ins, with targeting rates of around 37% for gene knockout. Thus, primary T cells are amenable to CRISPR-Cas9 gene editing, and the capacity to rapidly modify loci enables generation of primary T cell models suitable for comprehending the function of modified receptor-ligand pairs involved in an immune checkpoint response. Our pooled sgRNA-Cas9 screens in cancer cell lines have used our in-house sgRNA libraries, which include a modified tracrRNA component improving Cas9 affinity and subsequently the performance of a typical sgRNA for promoting gene editing. However, use of the same approach in primary T cells has not resulted in efficient transduction of the library. Specifically, isolated CD3+ T cells stimulated in vitro with anti-CD3 and anti-CD28 antibodies in the presence of recombinant IL-2 resulted in no expression or low level expression of GFP after cells were transduced with a one vector CRISPR-Cas9 sgRNA library. Our experiments indicate, in line with published data, that T cells can be transduced effectively with lentivirus, thus we are examining the use of a two vector CRISPR-Cas9 system and the use of CRISPRi to idealise CRISPR screening in primary T cells. We are also carrying out target identification and validation in myeloid derived suppressor cells (MDSCs). We are using an siRNA approach in these cells, which are generated by PBMC co-culture with cancer cell lines for 7 days, or by culture in the presence of recombinant GM-CSF and IL-6 for 7 days. Our initial data indicate that these MDSCs can effectively suppress autologous, as well as allogeneic, CD8 T cell proliferation mediated by anti-CD3 and anti-CD28 stimulation and that siRNA knockdown is effective in MDSCs. We will use our druggable genome plus arrayed siRNA library to identify targets that when knocked down inhibit the capacity of MDSCs to suppress T cell proliferation. We anticipate that these data will be useful in identifying new targets that are involved in regulating an immune response to tumour development and progression.

Citation Format: Cristina Ghirelli, Thibault Laurent, Simon Scrace, Kim Hoenderdos, Chris Lowe, Nicola McCarthy, Jonathan Moore. CRISPR-Cas9 and siRNA screening in primary human immune cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 4123. doi:10.1158/1538-7445.AM2017-4123

Abstract B086: CRISPR-Cas9 engineering and screening in primary human T cells

Recent clinical data indicate immunotherapy can be an effective treatment for cancer patients, yielding dramatically increased survival times in some cases. As not all patients benefit from treatments such as anti-CTLA4 and anti-PD1 antibodies, a major focus in immuno-oncology research is finding new immuno-oncology targets, including those that alter the character and frequency of T-cell-mediated anti-tumor responses.

We have had great success using CRISPR (Clustered Regularly Interspaced Short Palindromic Repeats)–Cas9 mediated genome editing to probe gene function in cancer cells via the generation of knock-out and knock-in mutants. We are now applying this approach to primary immune cells and are deploying both CRISPR–Cas9 cell engineering and CRISPR–Cas9 screens to better understand T cell biology and to find new therapeutic targets.

We use T cells negatively purified by magnetic sorting from peripheral blood mononuclear cells taken from healthy donors. Our initial work in primary human T cells has focused on the capacity to knock out and knock in genes using the Neon™ transfection system. Our data indicate that primary T cells are amenable to gene editing, and the capacity to rapidly modify loci, such as PDCD1, which encodes PD-1 enables generation of primary T cell models suitable for comprehending the function of modified receptor–ligand pairs involved in an immune checkpoint response.

Our pooled sgRNA–Cas9 screens have used our in-house sgRNA libraries, which include a modified tracrRNA component improving Cas9 affinity and subsequently the performance of a typical sgRNA for promoting gene editing and modifying phenotype. Briefly, isolated CD3+ T cells are stimulated in vitro with anti-CD3 and anti-CD28 antibodies in the presence of recombinant IL-2. Next, the proliferating T cells are co-cultured with a GFP expressing Lentivirus that directs expression of Cas9 and an sgRNA drawn from a 3900 member sgRNA library targeting genes involved in the regulation of metabolism and a control library of 2442 guide RNAs. After prolonged Lentivirus and T cell co-culture, transduced T cells are sorted based on their GFP expression and periodically re-stimulated with anti-CD3 and anti-CD28 antibodies in the presence of IL-2 to allow their proliferation and expansion over several weeks. Representative cell pellets are taken after GFP sorting and then at specific time points throughout the screen. For each time point, gDNA is extracted and PCR is carried out to isolate the gRNAs that are present in each cell and these are analysed using NGS. NGS results are interpreted using algorithms from the previously published model-based analysis of genome-wide CRISPR–Cas9 knockout (MAGeCK) and Bayesian normalisation of gene expression levels (BAGEL) approaches. These screens are currently ongoing and are being run in T cells isolated from five independent donors to assess the impact of donor variability.

We will present results from these screens assessing guide drop-out kinetics and reproducibility by comparing the performance of specific guides over multiple time points in each of the donors. We anticipate that these data will be useful in building more complex screens that assess T cell biology in the presence of additional cells, such as myeloid derived suppressor cells, involved in regulating the immune response to tumor development and progression.

Citation Format: Cristina Ghirelli, Thibault Laurent, Kim Hoenderdos, Chris Lowe, Nicola McCarthy, Jonathan Moore. CRISPR-Cas9 engineering and screening in primary human T cells [abstract]. In: Proceedings of the Second CRI-CIMT-EATI-AACR International Cancer Immunotherapy Conference: Translating Science into Survival; 2016 Sept 25-28; New York, NY. Philadelphia (PA): AACR; Cancer Immunol Res 2016;4(11 Suppl):Abstract nr B086.

Superradiant Emission from a Collective Excitation in a Semiconductor

We report an anomalous wide broadening of the emission spectra of an electronic excitation confined in a two-dimensional potential. We attribute these results to an extremely fast radiative decay rate associated with superradiant emission from the ensemble of confined electrons. Lifetimes extracted from the spectra are below 100 fs and, thus, 6 orders of magnitude faster than for single particle transitions at similar wavelength. Moreover, the spontaneous emission rate increases with the electronic density, as expected for superradiant emission. The data, all taken at 300 K, are in excellent agreement with our theoretical model, which takes into account dipole-dipole Coulomb interaction between electronic excitations. Our experimental results demonstrate that the interaction with infrared light, which is usually considered a weak perturbation, can be a very efficient relaxation mechanism for collective electronic excitations in solids.

The structure of a gene co-expression network reveals biological functions underlying eQTLs

What are the commonalities between genes, whose expression level is partially controlled by eQTL, especially with regard to biological functions? Moreover, how are these genes related to a phenotype of interest? These issues are particularly difficult to address when the genome annotation is incomplete, as is the case for mammalian species. Moreover, the direct link between gene expression and a phenotype of interest may be weak, and thus difficult to handle. In this framework, the use of a co-expression network has proven useful: it is a robust approach for modeling a complex system of genetic regulations, and to infer knowledge for yet unknown genes. In this article, a case study was conducted with a mammalian species. It showed that the use of a co-expression network based on partial correlation, combined with a relevant clustering of nodes, leads to an enrichment of biological functions of around 83%. Moreover, the use of a spatial statistics approach allowed us to superimpose additional information related to a phenotype; this lead to highlighting specific genes or gene clusters that are related to the network structure and the phenotype. Three main results are worth noting: first, key genes were highlighted as a potential focus for forthcoming biological experiments; second, a set of biological functions, which support a list of genes under partial eQTL control, was set up by an overview of the global structure of the gene expression network; third, pH was found correlated with gene clusters, and then with related biological functions, as a result of a spatial analysis of the network topology.

Cyclodextrin and maltodextrin finishing of a polypropylene abdominal wall implant for the prolonged delivery of ciprofloxacin

The aim of this work was to develop a polypropylene (PP) artificial abdominal wall implant for the prolonged release of ciprofloxacin (CFX). This sustained release effect was obtained by functionalization of the textile mesh with citric acid and hydroxypropyl-γ-cyclodextrin (HPγCD) or maltodextrin (MD). In both cases the textile finishing reaction yielded a cyclo- or malto-dextrin crosslinked polymer coating the fibers. The modified supports were characterized by thermogravimetric analysis (TGA), differential scanning calorimetry and scanning electron microscopy. The sorption capacities and the kinetics of CFX release were studied by batch tests coupled with spectrophotometric assays. Microbiological assays were carried out on Staphylococcus aureus, Staphylococcus epidermidis and Escherichia coli, while proliferation and viability tests used fibroblasts. The main results were as follows. (i) Due to the differences between the range of temperature of thermal degradation of the (cyclo)dextrins polymers and of the PP fibers TGA was a reliable method for quantifying the degree of functionalization of the textiles. (ii) Both modified supports showed improved sorption/desorption capacities for CFX, compared with the virgin mesh. The HPγCD-finished support showed an increased sorption capacity and a lower release rate of CFX compared with the MD modified support. (iii) Microbiological assays confirmed the latter result, with greater sustained antibacterial activity of the HPγCD treated support. These experiments have demonstrated the role of the cyclodextrin cavity in interactions with CFX: the antibiotic was not only adsorbed via hydrogen and acid-base interactions with the polyCTR-HPγCD network, but also via host-guest complexation. (iv) Biological tests revealed a slight decrease in fibroblast proliferation after 6 days on the modified supports, but cell viability tests showed that this was not due to toxicity of the (cyclo)dextrin polymer coatings.

Universal PCR assays for the differential detection of all Old World Leishmania species

For the epidemiological monitoring and clinical case management of leishmaniasis, determination of the causative Leishmania species gains importance. Current assays for the Old World often suffer from drawbacks in terms of validation on a geographically representative sample set and the ability to recognize all species complexes. We want to contribute to standardized species typing for Old World leishmaniasis. We determined the ribosomal DNA internal transcribed spacer 1 sequence of 24 strains or isolates, and validated four species-specific polymerase chain reactions (PCRs) amplifying this target. They discriminate L. aethiopica, L. tropica, L. major, and the L. donovani complex, use the same cycling conditions, and include an internal amplification control. Our PCRs amplify 0.1 pg of Leishmania DNA, while being 100% specific for species identification on an extensive panel of geographically representative strains and isolates. Similar results were obtained in an endemic reference laboratory in Kenya. Species could also be identified in clinical specimens. The presented PCRs require only agarose gel detection, and have several other advantages over many existing assays. We outline potential problems, suggest concrete solutions for transferring the technique to other settings, and deliver the proof-of-principle for analyzing clinical samples.

[Nipple sparing mastectomy: an update]

In order to decrease the psychological impact and the mutilating feeling of surgical treatments of the breast cancer when the mastectomy is indicated, authors described and propose the nipple sparing mastectomy (NSM). The only opposable criticism would be the increase of recurrence rate. The study of the recent literature allows us to make a inventory of fixtures concerning this evolution of the surgical practices whether on a technical, oncological, plastic or psychological plan. This technique is not validated in France and adjuvent therapies as the radiotherapy of the nipple are not validated yet. It seems that the NSM is a safe practice from the carcinologic point of view, while having a positive psychological impact in terms of disease and treatment acceptance. The technique seems possible after an information and selection of the patients and with a respect for technical rules (frozen section, peroperative evaluation of the nipple vitality).

Chemical, biological and microbiological evaluation of cyclodextrin finished polyamide inguinal meshes

This study describes the use of cyclodextrins (CDs) as a finishing agent of polyamide (PA) fibers used in order to obtain inguinal meshes with improved antibiotic delivery properties. The finishing process involved polymerization between citric acid and CDs, which yielded a cross-linked polymer that physically adhered to the surface of PA fibers. This permanent functionalization was characterized by evaluating the damping property with a polar liquid (glycerol) via the drop contact angle method for various rates of modification of the fabrics. The biological and microbiological effects of the PA, which were functionalized with hydroxypropylated derivate of gamma-CD (HP-gamma-CDs) and charged with ciprofloxacin (CFX), were evaluated by cell culture assays. We observed a good adhesion and proliferation of fibroblastic cells (NIH3T3) after 3 and 6 days and no detectable toxicity of the modified substrate. The in vitro antibacterial activity of the HP-gamma-CD grafted PA fabrics charged with CFX against the bacteria Staphylococcus aureus, Staphylococcus epidermidis and Escherichia coli was greatly superior to that of the virgin sample within a 24h batch experiment in human blood plasma medium. In conclusion, these results from our study offer an insight into the efficient performance of CDs as drug delivery systems for multiple applications in the fields of biomaterials and medical textiles.

Molecular dipstick test for diagnosis of sleeping sickness

Human African trypanosomiasis (HAT) or sleeping sickness is a neglected disease that affects poor rural populations across sub-Saharan Africa. Confirmation of diagnosis is based on detection of parasites in either blood or lymph by microscopy. Here we present the development and the first-phase evaluation of a simple and rapid test (HAT-PCR-OC [human African trypanosomiasis-PCR-oligochromatography]) for detection of amplified Trypanosoma brucei DNA. PCR products are visualized on a dipstick through hybridization with a gold-conjugated probe (oligochromatography). Visualization is straightforward and takes only 5 min. Controls both for the PCR and for DNA migration are incorporated into the assay. The lower detection limit of the test is 5 fg of pure T. brucei DNA. One parasite in 180 microl of blood is still detectable. Sensitivity and specificity for T. brucei were calculated at 100% when tested on blood samples from 26 confirmed sleeping sickness patients, 18 negative controls (nonendemic region), and 50 negative control blood samples from an endemic region. HAT-PCR-OC is a promising new tool for diagnosis of sleeping sickness in laboratory settings, and the diagnostic format described here may have wider application for other infectious diseases.

SPINE bioinformatics and data-management aspects of high-throughput structural biology

SPINE (Structural Proteomics In Europe) was established in 2002 as an integrated research project to develop new methods and technologies for high‐throughput structural biology. Development areas were broken down into workpackages and this article gives an overview of ongoing activity in the bioinformatics workpackage. Developments cover target selection, target registration, wet and dry laboratory data management and structure annotation as they pertain to high‐throughput studies. Some individual projects and developments are discussed in detail, while those that are covered elsewhere in this issue are treated more briefly. In particular, this overview focuses on the infrastructure of the software that allows the experimentalist to move projects through different areas that are crucial to high‐throughput studies, leading to the collation of large data sets which are managed and eventually archived and/or deposited.

Differential polyadenylation of ribosomal RNA during post-transcriptional processing in Leishmania

The protozoan parasite Leishmania belongs to the most ancient eukaryotic lineages and this is reflected in several distinctive biological features, such as eukaryotic polycistronic transcription and RNA trans-splicing. The disclosure of this organism's unusual characteristics leads to a better understanding of the origin and nature of fundamental biological processes in eukaryotes. Here we report another unusual phenomenon as we demonstrate that precursor ribosomal RNA can be extensively polyadenylated during post-transcriptional processingt. Furthermore, we demonstrate that the degree of precursor rRNA polyadenylation is variable in different strains and in the different life-stages of a strain.

Complexity of the major surface protease (msp) gene organization inLeishmania (Viannia) braziliensis: evolutionary and functional implications

The major surface protease (msp orgp63) ofLeishmaniaplays a major role in the host–parasite interaction. We analysed here the structure of the msp gene locus inLeishmania (Viannia) braziliensisand compared it to results obtained in other species. Physical mapping of cosmid contigs revealed a minimum of 37 genes per haploid genome and at least 8 different msp gene families. Within the same organism, these genes showed a nucleotide sequence varying in certain stretches from 3 to 34%, and a mosaic structure. From an evolutionary point of view, major differences were observed between subgeneraVianniaandLeishmania, both in terms of msp gene number and sequence. Within subgenusViannia, phenetic analysis revealed three clusters in which sequence variants ofL. (Viannia) braziliensisandL. (Viannia) guyanensiswere interspersed. Functional implications of our results were explored from predictedL. (Viannia) braziliensisprotein sequences: regions encoding the msp catalytic site showed a conserved sequence, while regions encoding surface domains possibly involved in the host–parasite interaction (macrophage adhesion sites and immunodominant B-cell and T-cell epitopes) were variable. We speculate that this would be an adaptive strategy of the parasite.

Hyaluronic acid accumulation; the mechanism behind graft rejection edema

Hyaluronic acid (HA) is an important stabilizing consistuent of the loose connective tissue and regulates water homeostasis. Thus, excessive accumulation of HA in interstitial tissue immobilizes water and may thereby contribute to interstitial tissue edema. By the use of biotin labelled core protein and an avidin-enzyme system, we visualized HA in grafted rat kidney, rat heart, rat small bowel and also in human kidneys. By an extraction procedure the tissue amounts of HA were measured in the experimental grafts. Simple techniques for measuring water content were also employed. The extracellular amounts of HA increased between 100% and 350% in rejecting tissues as compared to syngeneic controls. The relative water content also increased and correlated well with the HA accumulation. The clinical value of these experimental observations was confirmed in human transplantation where rejecting kidney allografts demonstrated a highly significant increase in HA staining in the interstitium as compared to non-rejecting biopsy specimens. We therefore concluded that transplantation edema--a key features of graft rejection--is regulated by the accumulation of HA not only under experimental conditions but also in the clinical setting.

Fun stories about Brucella: the "furtive nasty bug"

Although Brucella is responsible for one of the major worldwide zoonosis, our understanding of its pathogenesis remains in its infancy. In this paper, we summarize some of the research in progress in our laboratory that we think could contribute to a better understanding of the Brucella molecular virulence mechanisms and their regulation.

Selection of phage-displayed peptides recognised by monoclonal antibodies directed against the lipopolysaccharide of Brucella

Panning and screening of various phage display libraries with monoclonal antibodies (mAbs) directed against the O-chain of the lipopolysaccharide (LPS) of Brucella sp. allowed the identification of peptidic mimotopes of some O-chain epitopes. Four mAbs were tested. The A76-12G12 mAb, which is specific for LPS of all strains of Brucella, either A- or M-dominant, did not yield any peptidic mimotope, despite a specific yield enrichment during the rounds of panning. The B66-4F9 mAb, that recognises an epitope common to both Brucella sp. and Yersinia enterocilitca O:9 strains, allowed the selection of only one phage clone that was shown to be an antigenic but not immunogenic mimotope. The B66-2C8 and A15-6B3 mAbs, respectively, specific for the LPS of A-dominant and M-dominant Brucella sp., yielded several sequences, which allowed the determination of consensus sequences. These consensus will be of high interest for the construction of second generation libraries. For the best binding peptides, competition with LPS for the binding to the mAb is detected, which suggests that the peptides bind to the paratope of the mAb. The phages selected from the libraries were used to immunise mice, and a weak antibody response directed against LPS has been observed for some peptides. These data suggest that a subset of the selected peptides are immunogenic mimotopes of the LPS epitopes.

Antigenic properties of peptidic mimics for epitopes of the lipopolysaccharide from Brucella

The lipopolysaccharide (LPS) is up to now the only identified major virulence determinant of Brucella. This bacterium is responsible for brucellosis in animals and for Malta fever in humans. Several monoclonal antibodies (mAbs) directed against various LPS epitopes have been characterized. Two mAbs, named A15-6B3 and B66-2C8, directed against distinct LPS epitopes have been used to select peptides from 11 phage display libraries. The sequences of the selected peptides contain an overrepresentation of either proline or tryptophan residues when selected with either A15-6B3 or B66-2C8 mAbs, respectively. For the best binding peptides, competition with LPS for the binding to the mAb is detected, which suggests that the peptides bind to the paratope of the mAb. The phages selected from the libraries were used to immunise mice, and a weak antibody response directed against LPS has been observed. These data suggest that a subset of the selected peptides are mimotopes of the LPS epitopes.

Magnetic resonance detection of myelodysplasia in children with Currarino triad

PURPOSE

To evaluate the role of MRI in the detection of myelodysplasia in children with Currarino triad.

MATERIALS AND METHODS

Six patients (two girls, four boys, aged 7 months-14 years, mean age 6 years) were studied with MRI, voiding cystourethrogram and barium enema or fistulography. CT and ultrasonography were also performed in two patients.

RESULTS

All patients presented with partial agenesis of the sacrum. Three patients suffered from an intermediate form of anorectal malformation (ARM) and three had a high form of ARM. The presacral masses consistent with Currarino triad included anterior meningocoele in three patients, lipoma in two patients and anterior lipomeningocoele in one patient. MRI diagnosed tethering of the spinal cord in four of six patients. The tethering of the spinal cord was due to a lipomeningocoele in one patient, an intradural lipoma in one patient and a lipoma of the filum in two patients.

CONCLUSION

The association of Currarino triad with tethered spinal cord seems more common than generally reported in the literature. Preoperative MRI of the lumbosacral spine is essential to detect significant myelodysplasia in all patients with Currarino triad.

Abdominal actinomycosis associated with intrauterine device: CT features

Abdominal actinomycosis is a severe and progressive peritoneal infection, due to an anerobic gram-positive bacterium, Actinomyces israelii. The presence of a long-standing intrauterine device (IUD) is a well-known risk factor in young women. We report two cases of pelviperitoneal actinomycosis appearing in two young women with acute low abdominal pain. Abdominal CT demonstrated multiple solid or encapsulated peritoneal masses with marked contrast enhancement and infiltration of the adjacent mesenteric fat. Laparoscopy confirmed the presence of intraperitoneal abscesses which contained Actinomyces israelii. High doses of amoxicillin and clavulanic acid (Augmentine) were given and following CT scan after 2 and 6 weeks showed a slow, but complete, resolution of the lesions. Although the radiologic presentation of actinomycosis is nonspecific, the diagnosis should be raised in the presence of pseudotumoral mesenteric infiltration, particularly in young women with an IUD. Abdominal CT is a useful method for diagnosis and for follow-up.

Oxidant-antioxidant balance in granulocytes during ARDS. Effect of N-acetylcysteine

The production of cytotoxic oxygen radicals by activated granulocytes is a proposed mechanism of lung injury in ARDS. Protective effects of N-acetylcysteine (NAC) have been described in experimental and clinical ARDS. NAC could act in part by replenishing the intracellular stores of glutathione (GSH) in activated granulocytes, leading to detoxification of oxygen radicals produced by these cells. To test this hypothesis, 16 patients in the early phase of ARDS were randomized to receive either NAC (n = 8) or placebo (n = 8); granulocyte GSH, granulocyte oxygen radical production, and plasma levels of granulocyte elastase were measured in blood samples drawn sequentially within 8 h after the onset of ARDS (day 0), and then 24 (day 1), 72 (day 3), and 120 h (day 5) after the first sample; treatment with NAC or placebo was started immediately after day 0 and stopped just after day 3. Granulocyte GSH was significantly higher on days 1 and 3 when NAC was received by the patient. Unstimulated oxygen radical production, as measured ex vivo by luminol- and lucigenin-amplified chemiluminescence (CL), was higher in granulocytes from ARDS patients than from healthy control subjects, but was not influenced by NAC. The plasma levels of granulocyte elastase were five to eight times above the upper normal limit on day 0, decreased steadily until day 5, and were uninfluenced by NAC. In summary, parenteral NAC treatment started within 8 h of diagnosis increases the intracellular GSH in the granulocytes of ARDS patients without decreasing spontaneous oxidant production by these cells. The mechanisms of the protective effects of this drug previously reported in experimental and clinical ARDS remain to be established.

[Correlation between arthroscopy and MRI in the diagnosis of meniscal tears of the knee]

The sensibility and specificity of MRI diagnosis of meniscal tears are still debated. We compared the radiologic and arthroscopic diagnosis of 37 patients who underwent MRI study of the knee, followed by arthroscopic surgery. Meniscal lesions were classified according to their size and the grading system of Lotysch and Crues (1). In patients without previous arthroscopic surgery (n = 32), 92% of the grade-3b lesions are found to be torn at surgery. The probability for tears is weaker for grade-3a lesions (one meniscus torn out of three). An intact or slightly degenerated meniscus on MRI (grades 1 and 2) relates in 91% of cases to a normal fibrocartilage at arthroscopy. In patients with previous knee surgery (n = 5), the specificity of MRI for grade-3b lesions is weak (55%), owing to the presence of granulation tissue. Our results agree with those of recent publications, confirming the high value of MRI in the diagnosis of traumatic or degenerative meniscal tears. The use of a grading system incorporating the size of the lesion gives a better specificity to MRI diagnosis.

CD11b/CD18 expression, adherence, and chemotaxis of granulocyte in adult respiratory distress syndrome

The accumulation of granulocytes in the pulmonary microvasculature is generally thought a cardinal event in the pathology of adult respiratory distress syndrome (ARDS). However, the mechanism by which granulocytes are sequestered in the pulmonary vascular bed remains largely unknown. Because the CD11b/CD18 membrane receptors mediate various adhesion-dependent functions, their expression was investigated in granulocytes from patients during the course of ARDS development in relation to adherence and chemotaxis. CD11b expression of ARDS resting granulocytes was increased within 24 h of ARDS onset by a factor of two in comparison with control patients (p < 0.05) and remained significantly increased 72 to 120 h later. In contrast, the stimulated expression was significantly decreased only within 24 h of ARDS onset. Adherence was not modified within 8 h of the onset of ARDS, but was increased at Days 1, 3, and 5. The time course of granulocyte chemotaxis shows a decreased chemotaxis capacity during the first 3 d of ARDS, followed by normalization at Day 5. The dynamic changes observed in the various functions studied indicate a possible relationship between the modulation of the CD11b expression and a hyperadhesive state of granulocytes in ARDS. These sticky granulocytes may potentially contribute to the microvascular injury.