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J Convit

Publications and source records attributed to J Convit.

At least 91 records · Page 5Linked to original sources
PubMed1979

New method for estimating digestion of Paracoccidioides brasiliensis by phagocytic cells in vitro.

We describe a method by which phagocytosis and digestion of Paracoccidioides brasiliensis yeast cells by polymorphonuclear leukocytes or other phagocytic cells may be estimated. Suspensions of P. brasiliensis in its yeastlike phase were sonicated, counted, and incubated with known numbers of peripheral blood polymorphonuclear leukocytes. At given intervals, cytocentrifuge droplets were stained by a variation of Papanicolaou's method. Stained preparations were examined with phase-contrast optics. Digested organisms showed total or partial disappearance of protoplasm. Green-stained cell walls resisted digestion. The proportion of digested cells as a function of time was estimated.

Fungi↗
PubMed1979

In vitro activation of neutrophils by suspensions of Mycobacterium leprae.

Activation, defined as an increase in the proportion of cells that reduce nitroblue-tetrazolium in vitro, is present in neutrophils from patients with reactional lepromatous leprosy but not in neutrophils from patients with non-reactional lepromatous leprosy. Neutrophils from patients with all forms of leprosy are equally well activated by endotoxin in vitro. We have now shown that in vitro activation induced by Mycobacterium leprae suspensions is of comparable magnitude in neutrophils from patients with all forms of leprosy (including lepromatous and reactional lepromatous leprosy). There is no intrinsic neutrophil anergy in patients with lepromatous leprosy vis-à-vis M. leprae as pertains to activation. Spontaneous activation in reactional lepromatous leprosy is likely due to an indirect mechanism, probably of immunologic nature, and not simply to the presence of circulating Mycobacterium leprae in the blood.

Adolescent↗
PubMed1979

Immunological changes observed in indeterminate and lepromatous leprosy patients and Mitsuda-negative contacts after the inoculation of a mixture of Mycobacterium leprae and BCG.

This investigation was carried out to study the possibility of eliciting favourable immunological changes in small groups of Mitsuda-negative patients with indeterminate leprosy, lepromatous patients who were bacteriologically negative after prolonged treatment with sulphones, and in Mitsuda-negative contacts by means of stimulation with a mixture of autoclaved tissues from Mycobacterium leprae-infected armadillos and living BCG. A radical change was observed in the specific immunological activity of the indeterminate group, all of whom initially had occasional bacilli in cutaneous nerves in biopsies taken from hypopigmented spots, and in the persistently Mitsuda-negative contacts. The 48 hr and 30 day reactions to lepromin, the 48 hr reaction to supernatant antigen from lepromin, the test for bacillary clearence and in vitro lymphocyte transformation (LTT) to M. leprae from human and armadillo lesions all became positive. Of the lepromatous patients studied, only one became positive to all the criteria mentioned above. In the others, the 48 hr reaction to supernatant antigen, the LTT to antigen from a humn source, and the clearance test remained negative, while the Fernandez and Mitsuda reactions became positive. These results are discussed in terms of the possible use of this stimulation procedure in the prevention and immunotherapy of leprosy.

Adolescent↗
PubMed1977

[A clinical constelation in disuse: vitiligo, mastocytosis of the bone marrow, circulating heparinoid, chronic leg ulcer, hypoalbuminemia, ulcerative colitis and hepatic fibrosis].

We report an unusual case. Our patient had vitiligo, ulcerative colitis, hepatic fibrosis, hypoalbuminemia, bone marrow mastocytosis, a circulating heparinoid and chronic leg ulcers. The relationship between some of the components of this constellation seems logical. This is the case with bone marrow mastocytosis and circulating heparinoid. Also, between hypoalbuminemia and colitis and liver disfunction. On the other hand, the relationship between other features does not seem clear in the light of current knowledge.

Adult↗
PubMed1976

Physicochemical characteristics of the glycosaminoglycan-lysosomal enzyme interaction in vitro. A model of control of leucocytic lysosomal activity.

1. The activities of 30 different lysosomal enzymes were determined in vitro in the presence of the sulphated glycosaminoglycans, heparin and chondroitin sulphate, all the enzymes being measured on a density-gradient-purified lysosomal fraction. 2. Each enzyme was studied as a function of the pH of the incubation medium. In general the presence of sulphated glycosaminoglycans induced a strong pH-dependent inhibition of lysosomal enzymes at pH values lower than 5.0, with full activity at higher pH values. However, in the particular case of lysozyme and phospholipase A2 the heparin-induced inhibition was maintained in the pH range 4.0-7.0. 3. For certain enzymes, such as acid beta-glycerophosphatase, alpha-galactosidase, acid lipase, lysozyme and phospholipase A2, the pH-dependent behaviour obtained in the presence of heparin was quite different to that obtained with chondroitin sulphate, suggesting the existence of physicochemical characteristic factors playing a role in the intermolecular interaction for each of the sulphated glycosaminoglycans studied. 4. Except in the particular case of peroxidase activity, in all other lysosomal enzymes measured the glycosaminoglycan-enzyme complex formation was a temperature-and time-independent phenomenon. 5. The effects of the ionic strength and pH on this intermolecular interaction reinforce the concept of an electrostatic reversible interaction between anionic groups of the glycosaminoglycans and cationic groups on the enzyme molecule. 6. As leucocytic primary lysosomes have a very acid intragranular pH and large amounts of chondroitin sulphate, we propose that this glycosaminoglycan might act as molecular regulator of leucocytic activity, by inhibiting lysosomal enzymes when the intragranular pH is below the pI of lysosomal enzymes. This fact, plus the intravacuolar pH changes described during the phagocytic process, might explain the unresponsiveness of lysosomal enzymes against each other existing in primary lysosomes as well as its full activation at pH values occurring in secondary lysosomes during the phagocytic process.

Acid Phosphatase↗