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Biomedical subjects

D Landry

Publications and source records attributed to D Landry.

43 records · Page 3Linked to original sources
PubMed1985

Persistence of host Langerhans cells following allogeneic bone marrow transplantation: possible relationship with acute graft-versus-host disease.

Langerhans cells (LC) are bone marrow-derived dendritic antigen-presenting cells found in the epidermis. In an effort to determine the origin (host versus donor) of LC at different intervals following bone marrow transplantation, we performed skin biopsies in 16 recipients of sex-mismatched marrow. LC were identified using monoclonal antibody OKT6 in an indirect immunoperoxidase assay and their donor or host origin determined according to the presence or absence of Y body. The presence of Y-positive (donor) LC could be demonstrated in all (6/6) skin biopsies of female recipients of male marrow tested between days 39 and 730 post-transplant. Persistence of host LC in male recipients of female marrow was documented in all (6/6) recipients studied on day 39 and in two out of seven patients tested on day 120 post-transplant. From day 365 onward, no residual host LC could be detected, suggesting that by this time all epidermal LC are donor-derived. Our study demonstrates that host LC usually persist for 39 and up to 120 d following bone marrow transplantation. The relevance of this observation to the possible role of LC and other host dendritic antigen-presenting cells in the graft-versus-host reaction is discussed.

Acute Disease↗
PubMed1984

Study of Langerhans cells after allogeneic bone marrow transplantation.

We assessed the number of Langerhans cells (LC) before and after bone marrow transplantation (BMT) in 27 patients in order to study the fate and behavior of these dendritic antigen-presenting cells following allogeneic BMT. LC were identified using monoclonal antibody OKT6 on skin biopsies performed on days - 10, 0, 11, 25, 39, 120, and 365. In a control group composed of 15 healthy adults aged 20-37 yr, the mean number of LC (+/- SEM) was 25.6 +/- 1.17/0.1 sq mm of epidermal surface. Our study shows that pretransplant, the number of LC in patients with aplastic anemia or leukemia was lower than that of controls. The finding of low numbers of LC in patients with untreated aplastic anemia is suggestive of a medullary origin of LC in man. Moreover, during the early posttransplant period, nearly all patients present a severe deficit in LC. This deficit may delay the maturation of their immune system. The number of LC reaches nearly normal levels 4-12 mo after BMT. Finally, we have noted a significant impairment of LC reconstitution in patients with acute graft-versus-host disease (GVHD), providing evidence that this defect may be an important mechanism involved in acute GVHD-related immunodeficiency.

Acute Disease↗
PubMed1982

Depletion of somatostatin-like immunoreactivity in the rat central nervous system by cysteamine.

Selective neurotoxins have been of value in providing a means for specifically interfering with the actions of endogenous neurotransmitter candidates. Others have shown cysteamine (CSH) to deplete the gastrointestinal tract and hypothalamus of rats of immunoreactive somatostatin, suggesting a toxic action of that compound directed against somatostatin-containing cells. The present study further defines the actions of cysteamine on somatostatin in the central nervous system. (CNS). Cysteamine hydrochloride administered subcutaneously results in a depletion of somatostatin-like immunoreactivity (SLI) in the retina, brain, and cervical spinal cord of rats. The effect is demonstrable at doses of 30 mg/kg of body weight and above, occurs within 2 to 4 hr of a single injection of the drug, and is largely reversible within 1 week. The mean depletion of SLI observed within the CNS varies from 38% in cerebral cortex to 65% in cervical spinal cord 24 hr following administration of CSH, 300 mg/kg of body weight, s.c. By gel permeation chromatography, all molecular weight forms of SLI are affected, with the largest reductions in those forms that co-chromatograph with synthetic somatostatin-14 and somatostatin-28. These results indicate that CSH has a generalized, rapid, and largely reversible effect in depleting SLI from the rat CNS.

Animals↗
PubMed1977

[Confusional states in geriatrics].

Illustrated by clinical reports, this study attempts to demonstrate the practical and didactic interest of various somatopsychological correlations in geriatrics. The confusional state in the elderly has no specific etiopathogenesis. It is only the expression, often disconcerting, of a method of cerebral suffering and the clinician should be aware of its various presentations. The precipitating factors are not only of organic or iatrogenic origin, but often psychological. Any change is considered by the elderly patient as dangerous and worrying. Our perfectly justified fear of inaction and passivity together with a desire for rapid efficacy, should not lead us to forget that in geriatrics more than in any other branch of medicine, a prudent attitude in therapeutics is most likely to be successful.

Adaptation, Psychological↗
PubMedDate not supplied

Method for the quantification of alginate in microcapsules.

Alginate is a key reagent in the preparation of microcapsules for cell transplantation. To address the question of the intracapsular alginate concentration, a sensitive assay has been developed to quantify the alginate content of microcapsules. The method is based on the metachromatic change induced by alginate binding to the dye, 1,9-dimethyl methylene blue (DMMB). The assay has a high sensitivity and precision. It covers a wide concentration range enabling the measurement of alginate in dilute supernatants as well as in microcapsules. For the latter, the membrane is initially dissolved by incubating the microcapsules in an alkaline medium. The effect of potentially interfering substances (poly-L-lysine (PLL), citrate, chloride, sodium) and of pH has been studied. Poly-L-lysine interfered with the assay at pH 6.5 but not at pH 13. Interference by sodium augmented with increasing sodium concentration and reached a plateau at 200 mM. This problem was overcome by routinely adjusting all samples to 500 mM sodium. The other substances tested had a negligible effect on the assay. The reliable measurement of alginate with this new assay will allow the optimization of the intracapsular alginate concentration.

Alginates↗