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Biomedical subjects

G Taborelli

Publications and source records attributed to G Taborelli.

At least 19 recordsLinked to original sources
PubMed1994

Spontaneous production of granulocyte colony-stimulating factor in vitro by human B-lineage lymphocytes is a distinctive marker of germinal center cells.

The ability of human B lymphocytes to produce granulocyte (G)-CSF in vitro was investigated. Highly purified tonsillar B cells were fractionated into large and small cells by a Percoll density gradient, cultured, and tested for G-CSF gene expression. Large B cells spontaneous produced G-CSF mRNA and protein, whereas small B cells did not, even after incubation with various stimuli. Immunophenotypic analyses showed that large B lymphocytes contained approximately 60 to 70% of cells with the characteristic surface markers of germinal center (GC) B cells (CD38+, CD10+, and surface IgG+). The remaining cells expressed CD39, CD23, and surface IgD and were presumably in vivo-activated follicular mantle zone B cells. Fractionation of the large B lymphocytes into CD39+, surface IgD+, and CD39-, surface IgD- cells showed that the latter, but not the former, cell type produced G-CSF spontaneously in culture. Stimulation of purified (CD39-, surface IgD-) GC B cells with a CD40 mAb alone or in combination with IL-4 increased G-CSF production. Because these stimuli rescued a large fraction of GC cells (up to 50%) from spontaneous apoptosis in vitro, the finding may suggest that prevention of apoptotic death resulted in an increased G-CSF production or that CD40 mab and/or IL-4 increased G-CSF gene expression in G-CSF-producing GC B cells. Malignant B cells purified from the invaded lymph nodes of three patients with follicular center cell lymphoma and three Burkitt lymphoma cell lines, which had an immunophenotype identical with that of normal GC B cells, spontaneously produced G-CSF in vitro, thus confirming the GC origin of the cytokine. Incubation of normal purified GC B cells with rG-CSF resulted in the rescue of GC B cells from apoptosis, suggesting that G-CSF may be used by GC B cells in an autocrine manner. This autocrine loop of production and response to G-CSF by GC B cells may be activated by stimuli such as those delivered via the surface CD40 molecule, that participate in the rescue of GC B cells from apoptosis.

Adenosine Triphosphatases↗
PubMed1994

CD38 signaling by agonistic monoclonal antibody prevents apoptosis of human germinal center B cells.

The present study demonstrates that an agonistic anti-CD38 monoclonal antibody (mAb) (IB4) is capable of preventing apoptosis of human tonsillar germinal center (GC) B cells as measured by either morphological methods on Giemsa-stained cytospin preparations or flow cytometry on propidium iodide-stained cells. Two other anti-CD38 mAb (Leu-17 and OKT10) consistently failed to prevent apoptosis in the same cells, even when tested over a wide range of concentrations. Furthermore, exposure of GC B cells to IB4 mAb up-regulates the bcl-2 proto-oncogene product in a manner similar to that observed with CD40 ligand (CD40L). The ability of IB4 mAb to prevent apoptosis of GC B cells was inferior to that of both anti-CD40 mAb and CD40L. No synergistic or additive effects were observed when IB4 mAb was used together with CD40L. Unlike anti-CD40 mAb or CD40L, IB4 mAb neither induced a proliferation of GC B cells nor increased their proliferative response to anti-CD40, CD40L or recombinant interleukin-4, used alone or in combination. The present results are consistent with the recent findings on either the feature of the CD38 molecules to deliver activation signals and on the mechanisms of selection of B cells that operates in the GC.

ADP-ribosyl Cyclase↗
PubMed1994

Expression of CD5 and CD38 by human CD5- B cells: requirement for special stimuli.

In this study the mode of expression of CD5 by human tonsillar CD5- B cells after stimulation with different agents was investigated. Resting B cells were separated into CD5+ and CD5- cells and the two cell fractions exposed to phorbol 12-myristate 13-acetate (PMA). CD5- B cells expressed CD5 and maximum CD5 expression was achieved after approximately 60 h of culture. Based upon the proportions of cells that express CD5 as well as those of the cells surviving in culture, it was calculated that 15-25% of the total CD5- B cells were induced to express CD5. Unlike CD5- B cells, CD5+ B cells proliferated vigorously in response to PMA as assessed by [3H]thymidine incorporation and cell cycle analysis in vitro. However, the expression of CD5 by CD5- B cells was not related to the selective expansion of some CD5+ B cells left over as contaminant cells since this occurred in the absence of cell proliferation. Upon exposure to PMA, CD5- B cells remained in the G0-G1 phases of the cell cycle and did not express the Ki67 antigen or incorporate [3H]thymidine. Furthermore, mitomycin C treatment of the CD5- B cells did not prevent CD5 expression. Phenotypic studies disclosed that CD5+ B cells but not CD5- B cells expressed CD39. This finding offered the opportunity to carry out an additional control experiment. Separation of the two populations according to the expression of CD39 confirmed the finding obtained by fractionating the cells into CD5+ and CD5- B cells. The cells induced to express CD5 also expressed CD38 that was not detected on resting CD5- B cells. In this respect, the CD5- B cells that converted into CD5+ cells (inducible CD5+ B cells) resembled the cells from the CD5+ B cell fractions that up-regulated CD5 and also expressed CD38 upon exposure to PMA alone. Another example of coordinate expression of these two antigens was the finding that exposure to PMA in the presence of recombinant interleukin-4 (rIL-4) resulted in inhibition of the expression of CD5 and CD38. Although virtually all of the tonsillar CD5- B cells expressed the CD69 activation marker, no cells other than those co-expressing CD5 and CD38 were induced to express CD5 by PMA alone. Resting CD5- B cells failed to express CD5 and/or CD38 when cultured with PMA in the presence of EL4 T cells and IL-4-free T cell supernatants.(ABSTRACT TRUNCATED AT 400 WORDS)

ADP-ribosyl Cyclase↗
PubMed1993

Identification of two distinct CD5- B cell subsets from human tonsils with different responses to CD40 monoclonal antibody.

This study investigated the response of different CD5- B cell subsets to CD40 monoclonal antibody (mAb) in various combinations with interleukin (IL)-4 or rabbit anti-human mu chain antibody (a-mu-Ab). The different CD5- B cell subsets were isolated from tonsillar B cell suspensions depleted of CD5+ B cells and subsequently fractionated on Percoll density gradients. While resting CD5+ B cells proliferated and produced IgM molecules in response to a-mu-Ab, IL-4 and CD40 mAb as well as to Staphylococcus aureus Cowan strain I (SAC) and IL-2, resting CD5- B cells, which were co-purified in the same 60% Percoll fractions, consistently failed to respond. These cells were, however, activated by the stimuli employed, as demonstrated by their capacity to express the surface activation markers CD69, CD25 and CD71. Resting CD5+ B cells had the typical phenotype of mantle zone B cells (IgM+ IgD+ CD39+ CD38- CD10- CDw75dim), whereas resting CD5- B cells were CD38- CD39- CD10- CDw75 intermediate and expressed surface IgM but relatively little surface IgD and could not be classified as mantle zone or germinal center cells. The finding that purified germinal center cells (CD38+ CD10+ CD39- CDw75bright, IgG+) responded to CD40 mAb and IL-4 and also to SAC plus IL-2 further underlined the differences to resting CD5- B cells. However, some of the data collected suggest possible relationships between CD5- B cells and germinal center cells. The CD5- B cells isolated from the 50% Percoll fraction proliferated in response to a-mu-Ab, CD40 mAb and IL-4 as well as to SAC and IL-2. These cells had the same mantle zone B cell phenotype as the CD5+ B cells, but their capacity to respond to the stimuli in vitro was unrelated to a possible contamination with CD5+ B cells, as documented by the appropriate controls. Furthermore, upon exposure to SAC or phorbol esters, the large majority of CD5- B cells from the 50% Percoll fraction did not express surface CD5 and there was very little if any accumulation of CD5 mRNA. Finally, most of the cycling cells in the stimulated CD5- B cells did not express CD5. The CD5- B cells from the 50% Percoll fraction were comprised of a consistent proportion of cells that expressed surface activation markers.(ABSTRACT TRUNCATED AT 400 WORDS)

Antibodies, Monoclonal↗
PubMed1993

An assessment of the efficacy and tolerability of nimesulide vs paracetamol in children after adenotonsillectomy.

The efficacy and tolerability of nimesulide were assessed and compared with those of paracetamol in the treatment of 35 children with pain and inflammation following adenotonsillectomy. The antipyretic and analgesic efficacy of the 2 drugs was similar, although more patients had complete remission of pain after 4 days of treatment with nimesulide. Both drugs were well tolerated, even though occasional elevation of transaminase enzymes and alkaline phosphatase was noted in the nimesulide-treated group. It is postulated that this effect may have been attributable to the volatile anaesthetics used during surgery.

Acetaminophen↗
PubMed1990

Production rate and composition of cerumen: influence of sex and season.

The production rate and composition of cerumen have been studied in 11 participants (5 men and 6 women), 25 to 42 years old. The cerumen was obtained in January, May, July, and November to investigate the possible influence of the season. Only the triglyceride content decreased from November to July. Sex was not a factor, which supported the hypothesis that sex hormones play a minor role in the production rate of the lipid component of cerumen.

Adult↗
PubMed1986

A technique for measuring the rate of cerumen production.

A technique is described for quantitatively measuring the rate of cerumen production. Two different washing solutions were tried. A mixture of alcohol/ether (3:1 v/v) appeared to be the best extracting solution yielding 2.05 +/- 0.22 versus 0.73 +/- 0.14 mg/week per ear obtained with Triton X-100 solution. In addition, reproducibility was definitely better. Triton X-100 may be useful whenever microbiologic evaluations are requested. Total lipids accounted for 73.3% of cerumen extracted with the former solution, triglycerides being 19.5%, and cholesterol 7.2%. Our extracting technique appears to be a good estimate of the cerumen global output and may supply important information about cerumen in several biologic conditions.

Adult↗
PubMed1979

[Preferential staphylococcal colonizing site in the upper airway].

150 healthy individuals and 162 tonsillopathic patients were investigated for the presence of Staphylococcus species in the upper respiratory tract. S. epidermidis was isolated from the throat in a very small percentage of all the people examined. A great number of healthy individuals (40%) and of patients (70%) were colonized by S. aureus either in the nose or in the throat; 30% of the carriers harboured S. aureus exclusively in the tonsils and in the pharynx.

Adult↗