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Biomedical subjects

F Plenat

Publications and source records attributed to F Plenat.

At least 19 recordsLinked to original sources
PubMed2002

Osteochondroma after pediatric hematopoietic stem cell transplantation: report of eight cases.

Eight children developed osteochondroma (OS) at a mean of 88 months after hematopoietic stem cell transplantation (HSCT). The mean age at HSCT was 56 months (12-84). This represents a cumulative incidence of 20% among patients less than 18 years of age transplanted from 1981 to 1997. These eight patients underwent allogeneic (n = 2) or autologous (n = 6) transplantation for either acute leukemia (n = 6) or neuroblastoma (n = 2) after a conditioning regimen including TBI (n = 7) or a combination of Bu and CY. OS was multiple in seven patients and solitary in one. Eight lesions were resected and all were benign. Four children received growth hormone before diagnosis of OS, but there was no clinical, radiological or histological difference between those who did not. Univariate analysis showed an increased rate associated only with autologous HSCT, with a 31.7% probability of a new OS at 12 years after HSCT. Osteochondroma should be added to the other adverse effects of HSCT in children.

Actuarial Analysis↗
PubMed2001

Successful reinfection of chronically infected mice by a different Toxoplasma gondii genotype.

It is generally assumed that primary infection by Toxoplasma gondii protects from reinfection. A recent study using a murine model has questioned this dogma using indirect procedures to detect the reinfecting strain. We have reinvestigated this issue using a transfected strain of T. gondii (Prugniaud beta galactosidase: Pru beta gal) which expresses Escherichia coli beta-galactosidase. Detection of enzyme activity on fixed parasites allows a direct distinction between transfected and untransfected strains. We have found that in OF1 mice primary infection with the 76 K strain of T. gondii fully protects mice against tissue cyst production upon reinfection with the Pru beta gal T. gondii strain whereas primary infection with the Pru beta gal T. gondii strain does not impair tissue cyst formation upon reinfection with the Ned strain of T. gondii, which belongs to another T. gondii genotype. These results suggest that the immune protection conferred by one strain of T. gondii can be breached by reinfection with a strain belonging to another genotype; which can have significant consequences in human or veterinary medicine.

Animals↗
PubMed2001

[Sinobronchial syndrome].

The sinobronchial syndrome consists of chronic sinusitis and chronic nonspecific inflammation of the lower airways, typically chronic bronchitis, bronchiectasis and diffuse panbronchiolitis. This airway disease of unknown etiology is not related to smoking. It is common in Japan and is poorly described in western countries. We report a case in a non-Asian patient. The known efficacy of long-term low-dose erythromycin therapy justifies careful diagnosis of sinobronchial syndrome in patients of non-Asian ethnic origin.

Anti-Bacterial Agents↗
PubMed1999

Pathological fracture in non-ossifying fibroma with histological features simulating aneurysmal bone cyst.

A 12-year-old-girl presented with a fracture of an osteolytic lesion of the distal radius. A 7-year-old girl presented with a fracture of an osteolytic lesion of the femoral shaft. In both cases it was a non-ossifying fibroma with fracture misdiagnosed at pathology as aneurysmal bone cyst. Fractures through non-ossifying fibromas may alter the histological pattern of the initial lesion in two ways: firstly, by the presence of blood pigments due to the fracture, and secondly, by formation of new bone. Radiological-pathological correlation is essential to avoid histological errors after pathological fracture in a non-ossifying fibroma.

Bone Cysts, Aneurysmal↗
PubMed1999

Assimilation of [57Co]-labeled cobalamin in human fetal gastrointestinal xenografts into nude mice.

Cobalamin (Cbl) and its Cbl-binding proteins are present in amniotic fluid. Because amniotic fluid is swallowed by the embryo-fetus, we studied the ability of Cbl to be transported and metabolized across the embryo-fetal digestive tract. Human embryonic stomachs and intestines were transplanted into nude mice. The basal secretion of Cbl-binding proteins was studied by gel filtration of the graft juices. Intrinsic factor (IF) was looked for in gastric mucosa by immunohistochemistry. The uptake of [57Co]-labeled Cbl by the intestinal graft was studied by Schilling tests and HPLC. IF, haptocorrin, and a transcobalamin-like protein were detected in gastric juice, with concentration ranges of 5.0-26.4, 1.9-27.1, and 5.2-12.6 pmol/mL, respectively. The IF [57Co]Cbl complex had a single isoprotein with a pI at 5.6, which was maintained after incubation with neuraminidase. Urine excretion percentages (Schilling tests) ranged from 5.5 to 21.2% and from 0.3 to 1.6% when cyano-[57Co]Cbl-IF or cyano-[57Co]Cbl, respectively, was instilled in intestinal grafts. Chloroquine reduced significantly the percentage of excreted [57Co]Cbl. The [57Co]Cbl was mainly excreted as cyano-[57Co]Cbl in urines, showing a low coenzyme conversion. In conclusion, IF is secreted by the nonstimulated embryonic stomach and lacks sialic acid. Cbl binds to it and is subsequently transported across the xenografted embryo-fetal intestine. This suggests that amniotic fluid may contribute to Cbl delivery to the embryo-fetus.

Amniotic Fluid↗
PubMed1997

Unusual manifestations of hypersensitivity after a tick bite: report of two cases.

BACKGROUND: Ticks are able to transmit, through biting, various viral, parasitic, and bacterial diseases, the best known being Lyme disease due to Borrelia burgdorferi. In addition, ticks may also induce allergic reactions. OBJECTIVE: A study of immediate and delayed skin reactions are undertaken to give evidence of an IgE-dependent mechanism. METHODS: Two lumbermen reported having had skin reactions following bites by ticks. Skin prick tests and intradermal tests were performed with what was most probably Ixodes ricinus extract in one case. Specific IgE to whole body extract of wood tick were assayed by radioimmunoassay. Histological and immunohistologic examinations of skin biopsy obtained from a pruriginous skin lesion and from a delayed reaction following the intradermal test, were performed. RESULTS: One of them had positive immediate reactions to a prick test and an intradermal test with the same extract. Both patients had significant levels of wood tick-specific IgE antibody as well as elevated serum total IgE levels. Histologic examinations of a pruriginous lesion revealed lymphocytic dermal and perivascular infiltration, with evidence of CD8+ T lymphocytes and Langerhans' cells in the perivascular infiltrates. A biopsy of the place of the delayed reaction following the intradermal skin test also showed the presence of dermal and perivascular lymphocytic infiltrates. CONCLUSION: IgE-dependent allergy to Ixodes ricinus can explain allergic reactions. Standardized extracts have to be prepared with sufficient amounts of the relevant tick salivary antigens to permit diagnosis by skin and serologic tests of patients, especially lumbermen who may be allergic to Ixodes ricinus.

Adult↗
PubMed1997

[Amplification of immunologic reactions using catalytic deposition at the reaction sites of tyramine derivatives. A decisive gain in sensitivity in immunohistochemistry and in situ hybridization].

In the catalyzed reporter deposition technique, horseradish peroxidase catalyzes the activation of conjugated phenolic compounds resulting in the covalent binding of the radicalized intermediates to electron rich moieties in the protein molecules present at the site of reaction. Comparing the biotinyl-, digoxigeninyl-, and fluoresceinyl-derivatives of tyramine and four immunohistochemical formats, we showed that the most sensitive detection system was that using biotinyl-tyramide and an immunohistochemical technique using a biotinylated secondary antibody followed by a streptavidin peroxidase. Amplification without background staining was obtained in most biotin rich tissues with digoxigeninyl-tyramide. With fluoresceinyl-tyramide, clear signal amplification was observed in the fluorescent microscope. Finally, when compared with standard methods, increased sensitivity was obtained with the fluorescent derivative for detection of hybridized sequences in interphase chromosomes.

Binding Sites↗
PubMed1997

[Malignant non-Hodgkin lymphoma of the central nervous system with ocular site. Value of vitrectomy for diagnosis].

Diagnosis of intraocular lymphoma is difficult and should be considered in middle-aged or older patients with a chronic uveitis. Many explorations (lumbar punctures, brain imaging and vitrectomies) may be needed before correct diagnosis is made. We report the case of a 50-year-old woman with an intraocular lymphoma for whom the diagnosis was confirmed by a vitrectomy.

Central Nervous System Neoplasms↗
PubMed1997

[Chronic sclerodermiform syndrome disclosing subcutaneous T-cell lymphoma].

INTRODUCTION: Subcutaneous tissue is an uncommon primary localization for T-cell lymphomas. Panniculitis with recurrent papulonodules are reported in most cases. CASE REPORT: We report a case in which small-cell pleiomorphic non-Hodgkin lymphoma developed initially in subcutaneous tissue followed by secondary systemic extension. The first clinical manifestation was a sclerodermiform syndrome involving the four limbs. DISCUSSION: This type of lymphoma appears to have a polymorphic clinical presentation. Physicians should be aware of this type of lymphoma and use immunohistological techniques for early diagnosis.

Fatal Outcome↗
PubMed1996

The trypsin-induced leucostasis which leads to emphysema in the hamster is not due to contaminating endotoxins.

Intravenous injection of trypsin in the rat induces early lung leucostasis and emphysema of delayed onset. This report confirms that this emphysema is not rat-specific and that the leucostasis is not related to the presence of contaminating endotoxin in the trypsin. In hamsters (n = 37), leucostasis did not occur when they were injected with heat-treated trypsin, but numerous granulocytes were sequestered in the vessels of hamsters receiving a fresh solution of trypsin. In these hamsters, the number of granulocytes harvested by lavage increased significantly (1.87 x 10(6) per ml, P < 0.001) compared with hamsters injected with either heat-denatured trypsin (0.89) or saline (0.86), or compared with controls (0.86). Emphysema was inconstantly observed in hamsters 6 or 12 weeks after injection with trypsin for 1 h. It was frequently (17/20) present and always (20/20) well developed (intercept + 180 per cent) in the 2-h perfused hamsters whose lungs were abnormally heterogeneous (index + 100 per cent) relative to the seven controls and to the nine saline-injected hamsters. The efficiency of trypsin in triggering emphysema (percentage of hamsters having abnormal values of intercept) was dependent on the time of perfusion. This form of experimental emphysema is thus considered to be due to an endotoxin-independent leucostasis.

Animals↗
PubMed1996

Animal models of antisense oligonucleotides: lessons for use in humans.

The ability of oligonucleotides to inhibit genetic expression in a sequence-specific manner has been well documented. Because of their potential for exquisite specificity, oligonucleotides have been proposed as therapeutic agents for a variety of human diseases, including cancers, microbial infections and autoimmune disorders. Approximately 16 clinical trials are currently in progress. However, relatively little is known about the in vivo behaviour of oligonucleotides. Extrapolations from in vitro studies to predict in vivo pharmacokinetics and effects in humans might be difficult and inappropriate. Animal models still remain an essential tool in the development of oligonucleotides as efficient drugs in humans.

Animals↗
PubMed1996

Evaluation of Pyloriset Dry, a new rapid agglutination test for Helicobacter pylori antibody detection.

We evaluated the performance of a new latex agglutination test, Pyloriset Dry (Orion Diagnostica, Espoo, Finland), in the simultaneous detection of immunoglobulin G (IgG), IgA, and IgM antibodies to Helicobacter pylori and compared it with that of the Pyloristat test (BioWhittaker, Fontenay-sous-Bois, France), an enzyme-linked immunosorbent assay detecting IgG to H. pylori, for 96 untreated dyspeptic patients who had undergone gastroduodenal endoscopy. Infection was diagnosed in 56 cases by positive culture and/or positive Giemsa stain and rapid urease test (antral biopsies) and was associated with chronic gastritis in 52 patients. Forty noninfected patients did not have chronic gastritis. The sensitivity of Pyloriset Dry was 91.1%. The sensitivity of Pyloristat was 91.1 or 82.1%, depending on whether equivocal results were considered positive or negative, respectively. Both tests had a specificity of 87.5%. Their performances were not statistically different. Thus, Pyloriset Dry is an alternative to serological tests for adults, particularly when a small number of serum samples has to be tested.

Adult↗
PubMed1995

Cell and tissue distribution of synthetic oligonucleotides in healthy and tumor-bearing nude mice. An autoradiographic, immunohistological, and direct fluorescence microscopy study.

Antisense oligonucleotides have the ability to inhibit individual gene expression in the potential treatment of cancer and viral diseases. However, the way parenterally administered oligonucleotides distribute themselves into healthy tissues or tumors is poorly understood. In this study, the cell and tissue distribution of two modified or unmodified phosphodiester pentadeca-beta-oligonucleotides intravenously administered to healthy or tumor-bearing nude mice was assessed by autoradiography as well as by direct fluorescence and immunoenzymatic histological methods. Resistance of oligonucleotides to degradation by nuclease activity was previously studied in vitro. Using these methods we were able to show the following: 1) within minutes, oligonucleotides permeate all cells and tissues with the exceptions of erythrocytes and intervertebral discs; 2) cell and tissue distribution does not depend on the sequence of the given oligonucleotide; 3) concentration of oligonucleotides is higher within the connective tissue cells than in the interstitial matrix; 4) after uptake, oligomers partition throughout all of the cellular compartments, including at the highest intracellular concentrations in the nuclei; 5) oligonucleotides penetrate easily the tumor cell compartments, oligonucleotide diffusion being unimpeded by the extracellular matrix.

Animals↗
PubMed1994

Blood monocyte chemotaxis.

Migration is a prerequisite for blood monocytes to exert their biological activities, since they have to migrate from blood into the tissues where they transform into macrophages. In vivo chemotaxis of blood monocytes is seldom evaluated, while their in vitro ability to migrate is frequently tested. The most frequently used test relies on BM migration through filters using modified Boyden chemotactic chambers. Using checkerboard analysis it is possible to define chemotactic and chemokinetic factors.

Biological Assay↗
PubMed1993

Squamous metaplasia expression of proto-oncogenes and P 53 in lung cancer patients.

BACKGROUND: The question of whether bronchial squamous metaplasia is a true preneoplasia is important and demonstrated in animal for several carcinogens. We have now approached this problem in humans and in vivo. EXPERIMENTAL DESIGN: Squamous metaplasia in the close vicinity of surgically resected lung tumors were evaluated for their mitotic index and screened for proto-oncogenes and P 53 protein expression by immunohistochemistry and/or in situ hybridization. RESULTS: Among 16 patients, 4 had squamous metaplasia positive for either myc messages and/or for P 53 protein accumulation. In the same patients (3/4), the autologous bronchial tumors were also positive for the same markers. Squamous metaplasia positivity was observed essentially in patients with advanced diseases and only in squamous cell carcinomas. In addition, when evaluated with 5 iodo-2'-deoxyuridine systemic infusion, all patients presented hyperproliferative basal squamous metaplasic cells. CONCLUSIONS: These results are reminiscent of the typical preneoplastic changes observed in familial colic adenomatosis, where genetic changes accumulate in hyperproliferative cells. They also suggest that bronchial squamous metaplasia could be an authentic preneoplasia in, at least, squamous cell carcinomas.

Gene Expression Regulation, Neoplastic↗