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D Thierry

Publications and source records attributed to D Thierry.

At least 37 records · Page 2Linked to original sources
PubMed1996

[Therapeutic approaches of hematopoietic syndrome following accidental total whole body irradiation].

Since the first radiation accidents which resulted in severe health effects in the workforce or the population, great progress has been made in the fields of diagnosis, prognosis and treatment of accidentally overexposed victims. Since then, progress has also been made in the medical management of diseases such as aplasia. Because of the relative scarcity of radiation accidents, there is a need for complementary researches, in order to take advantage of new techniques and medical approaches. After whole body overexposure, the key issue is the therapeutic decision, ie, the choice between bone marrow transplantation and other strategies. The indications of bone marrow transplantation cover only a short range of doses, provided the exposure is distributed uniformly within the body. The last accidental overexposures which happened in the world have demonstrated the possible efficiency of haematopoietic growth factors, most of them being still under clinical trials. Actions based on these various approaches are summarized, as well as the lessons which have been learned.

Adult↗
PubMed1995

Haematopoietic growth factors in the treatment of therapeutic and accidental irradiation-induced bone marrow aplasia.

Bone marrow aplasia is one of the main syndromes following a high dose accidental exposure of ionizing radiation. Although both transfusion and bone marrow transplantation have been used with some success since the first treatments of patients, other therapeutic strategies are needed. The strategies involving haematopoietic growth factors for the treatment of radiation victims have been explored in vivo mainly in animal models and it is hoped that new therapeutic regimens will be elucidated from such approaches. The growth factors stimulate proliferation and/or differentiation of haematopoietic progenitor cells and possible stem cells. Furthermore, they act on the functions of mature cells. They now have specific uses in haematology, related to their role in the regulation of growth and differentiation of haematopoietic progenitor cells. The results of the clinical trials, performed with numerous patients and often randomized bring important clues about what to expect from growth factor therapy. Other factors are only entering the preclinical or clinical trials now. Although numerous in vitro or in vivo experiments suggest a benefit from their effects, their possible uses in therapy are still questionable. Some growth factors have already been used for the treatment of accidental radiation-induced aplasia and lessons have been learned from their medical management and follow-up.

Accidents↗
PubMed1994

Differentiation of human mast cells from bone-marrow and cord-blood progenitor cells by factors produced by a mouse stromal cell line.

Human bone-marrow or cord-blood progenitors (i.e., CD34+ cells) are easily purified by immunological methods and can be cultured on normal human-bone-marrow stromal cells for limited periods of time. Under these culture conditions, the number of progenitors declines in a few weeks and these cells disappear completely in less than 8 weeks. This fact suggests that this culture system is deprived of growth factor(s) able to support the self-renewal of stem cells. We have developed the culture of immunomagnetically purified human-bone-marrow- or cord-blood-derived CD34+ cells on a supportive mouse lipoblastic stromal cell line, MS-5. The long-term survival of clonogenic cells was analyzed in these cultures and compared with the results obtained by culture on human-bone-marrow stromal cells. The results demonstrated that only coculture of CD34+ cells on MS-5 layers allows the survival of clonogenic progenitors for at least 12 weeks. Cytospin smears were regularly performed and cell morphology was examined after classical staining methods (i.e., M.G.G. and toluidine blue staining). Histologic analysis demonstrated the growth of mast-cell-like metachromatic cells after the second week of incubation on MS-5 layer. The highest percentage of these cells was observed after 8 weeks, and averaged about 30 percent for cord-blood cells and 70 percent for bone-marrow cells. To further confirm the nature of the metachromatic cells obtained under this culture condition, immunohistochemical staining of tryptase was performed on the same samples. The results demonstrated similar percentages of tryptase+ cells and of metachromatic elements. Measurement of cellular histamine demonstrated that culture of CD34+ cells on MS-5 monolayers induced the formation and increase of this mediator. To determine whether the contact between MS-5 layers and CD34+ cells was an absolute requirement for the development of mast cells, CD34+ cells were cultured in the presence of MS-5 conditioned medium. This condition allowed the development of similar percentage of mast cells when compared with the coculture experiments, indicating that a soluble factor was involved in mast cell differentiation. Whatever the soluble factor(s) responsible for this mast cell growth activity, our culture system allows us to obtain significant amounts of highly enriched normal human mast cell populations useful for further studies on the reactivity of this cell subset.

Animals↗
PubMed1994

Electrochemical and XPS studies of titanium for biomaterial applications with respect to the effect of hydrogen peroxide.

Electrochemical measurements, x-ray photoelectron spectroscopy, and scanning tunneling microscopy have been used to study the effect of hydrogen peroxide on the passivity of titanium in a phosphate-buffered saline (PBS) solution. The results indicate that the passive film formed in the PBS solution--with and without addition of H2O2--may be described with a two-layer structure model. The inner layer has a structure close to TiO2 whereas the outer layer consists of hydroxylated compounds. The introduction of H2O2 in the PBS solution broadens the hydroxylate-rich region, probably due to the formation of a Ti(IV)-H2O2 complex. Furthermore, the presence of H2O2 results in enhanced dissolution of titanium and a rougher surface on a microscopic scale. Finally, a dark pigmentation (blue color) is observed when titanium has been exposed--for several weeks--to PBS with additions of H2O2.

Color↗
PubMed1994

Comparison of polymerase chain reaction and non-radioactive hybridization techniques for the identification of Mycobacterium avium strains.

A polymerase chain reaction able to amplify specifically a 205-base-pair DNA fragment of Mycobacterium avium genome was used and compared to a nonradioactive hybridization assay (AccuProbe) and to conventional biochemical identification. The PCR approach to diagnosis of M. avium infection is a valid diagnostic alternative to the more classical procedures.

Base Sequence↗
PubMed1994

Molecular epidemiology of Legionella pneumophila serogroup 1 by ribotyping with a non-radioactive probe and PCR fingerprinting.

Hybridization with acetylaminofluorene-labelled 16 + 23 S rRNA from Escherichia coli was used to detect DNA polymorphism among Legionella pneumophila serogroup 1 isolates. Isolates from unrelated patients showed at least four different rRNA restriction patterns, whereas those from related patients showed a single pattern. Amplification of genomic regions with an arbitrary primer by polymerase chain reaction was used to further analyze the isolates. Related isolates showed closely related patterns while unrelated isolates displayed six distinct patterns. We could differentiate the majority of unrelated isolates with the combination of the patterns obtained with the ribotyping and the PCR fingerprinting, while strains from the same outbreak remained highly related. The ribotyping and the PCR fingerprinting are proposed as useful and easy to perform epidemiological markers of L. pneumophila serogroup 1 infection.

Base Sequence↗
PubMed1994

Isolation of an insertion sequence (IS1051) from Xanthomonas campestris pv. dieffenbachiae with potential use for strain identification and characterization.

A new insertion sequence was isolated from Xanthomonas campestris pv. dieffenbachiae. Sequence analysis showed that this element is 1,158 bp long and has 15-bp inverted repeat ends containing two mismatches. Comparison of this sequence with sequences in data bases revealed significant homology with Escherichia coli IS5. IS1051, which detected multiple restriction fragment length polymorphisms, was used as a probe to characterize strains from the pathovar dieffenbachiae.

Base Sequence↗
PubMed1993

Blood banking for hematopoietic stem cell transplantation.

The number of umbilical cord cell transplants is increasing worldwide. The results are comparable to allogeneic bone marrow transplantation in a large variety of hematological diseases that are curable by bone marrow transplantation and, so far, the incidence of graft-versus-host disease has been limited. The advantages of using cord blood are related to the high number of hematopoietic progenitors present in the circulation at birth and to the relative immune immaturity of the newborn. A project is described to establish a European cord blood bank in order to obtain related or unrelated, matched or mismatched hematopoietic stem cells for transplantation to patients without a bone marrow donor.

Blood Banks↗
PubMed1993

Long-term bone marrow culture in Fanconi's anaemia.

Fanconi's anaemia (FA) is the most common of the constitutional aplastic anaemias; the mechanisms leading to aplasia in this disease are poorly understood. A number of mechanisms have been implicated in the pathogenesis of acquired aplastic anaemia (AA), including a stem cell defect, an immune reaction against haematopoietic cells or defective function of the marrow microenvironment. To investigate the pathophysiology of this disorder we have performed bone marrow colony forming unit-granulocyte macrophage (CFU-GM) assays and long-term bone marrow culture (LTC) in 22 cases of FA compared with 17 cases of acquired AA. Defective in vitro haematopoiesis was observed in all patients with FA, including several cases with normal peripheral blood counts. The mean CFU-GM value for the FA group was approximately 15 times lower than for the normal group. A correlation was seen between CFU-GM and the severity of neutropenia in FA. In LTC an adherent layer formed in all cases of FA; despite this fact CFU-GM were either not generated or rapidly fell to zero in all patients. LTC is a sensitive method for the detection of impaired granulopoiesis in FA and reveals defects in all patients with this disease.

Adolescent↗
PubMed1993

The expression of cytokine and cytokine receptor genes in long-term bone marrow culture in congenital and acquired bone marrow hypoplasias.

A number of cytokines have been shown to have stimulatory activity on multipotent haematopoietic precursors. These include kit ligand (KL), interleukins (IL) 1, 3 and 6 and granulocyte macrophage-colony stimulating factor (GM-CSF). Using reverse transcriptase/polymerase chain reaction method (RT/PCR) we have examined the expression of these cytokines, the c-kit and IL-6 receptors, in long-term bone marrow culture (LTC) adherent layer cells in human bone marrow hypoplasia syndromes. Disorders studied include Fanconi's anaemia (FA, n = 16), idiopathic aplastic anaemia (AA, n = 11), Seckel's syndrome (n = 2), dyskeratosis congenita (n = 2), Shwachman-Diamond syndrome (n = 1), thrombocytopenia with absent radii syndrome (n = 1), acquired amegakaryocytosis (n = 1), paroxysmal nocturnal haemoglobinuria (n = 1) and acquired agranulocytosis (n = 1). IL-6 and GM-CSF expression appeared reduced in most patients with FA, suggesting that impaired production of these cytokines may contribute to the bone marrow failure seen in most patients with FA. In contrast, abundant IL-6 and GM-CSF expression were seen in most patients with AA when compared with the FA group and controls; these may be mediators of a stromal response in this disorder. No obvious differences were seen between the different patients' groups and controls in expression of the other cytokines or cytokine receptors studied.

Anemia, Aplastic↗
PubMed1993

Use of the insertion element IS6110 for DNA fingerprinting of Mycobacterium tuberculosis isolates presenting various profiles of drug susceptibility.

IS6100 is an insertion sequence of the IS3 family and it is present in multiple copies in the chromosome of Mycobacterium tuberculosis. Four to 15 copies are present in various strains of M. tuberculosis. In this study, the value of IS6110 as an epidemiological marker of tuberculosis was examined. Unrelated clinical strains from Greek patients presented, in restriction fragment length polymorphism analysis, a high degree of polymorphism, whereas patterns of related clinical strains from familial outbreaks were identical. Since RFLP analysis with acetylaminofluorene labeled IS6110 as the probe gave satisfactory results, it is suggested that this non-radioactive probe can be used in hospitals and health centres for the epidemiological survey of M. tuberculosis infections.

2-Acetylaminofluorene↗
PubMed1993

Isolation of specific DNA fragments of Mycobacterium avium and their possible use in diagnosis.

We cloned and sequenced two DNA fragments (DT1 and DT6) from Mycobacterium avium serotype 2 for use in the identification of members of the M. avium-M. intracellulare complex (MAC). Reference strains of MAC belonging to serovars 1 to 28 were examined by using these DNA fragments as probes. The study revealed that the DT6 probe hybridized with DNAs from M. avium strains (serovars 1 to 6, 8 to 11, and 21), while the DT1 probe hybridized with DNAs from serovars 2, 3, 7, 12 to 20, and 23 to 25. DT1- and DT6-derived oligonucleotides were selected for use as primers in a polymerase chain reaction test. Amplification of the DT1 and DT6 sequences may provide the basis for a rapid and reliable assay for the detection of mycobacteria belonging to MAC.

Animals↗