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J Izard

Publications and source records attributed to J Izard.

At least 55 records · Page 3Linked to original sources
PubMed1984

Natural killer activity of Kurloff cells: a direct demonstration on purified Kurloff cell suspensions.

In order to study their natural killer effect, guinea pig splenic Kurloff cells were fractionated by Percoll discontinuous density gradient centrifugation. Kurloff cells were collected and tested for cytotoxicity in a 24-hr chromium-release test. Comparison of different splenic cellular samples (of males or estrogenized females) with increasing percentage of Kurloff cells, revealed a highly significant positive correlation (r = 0.93, alpha less than 0.01) with the cellular cytotoxicity developed against the K 562 target cells.

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PubMed1984

Isolation of Kurloff cells by Percoll density gradient centrifugation. Protein labeling with 35S-methionine of these cells.

Large populations of splenic Kurloff (150 - 200 X 10(6) Kurloff cells) were obtained from estrogenized guinea pigs by isopycnic centrifugation in a Percoll solution of 1.085 g/ml starting density. The Kurloff cells settled at a buoyant density of about 1.100 g/ml. The purity of these cell suspensions reached 95%, as assessed by phase contrast microscopy and by specific staining. The viability assessed by Trypan blue exclusion test was also about 95%. Moreover, the good transmission electron microscopic appearance of these Kurloff cells and their ability to take up 35S-methionine in culture confirmed their physiological integrity. By autohistoradiography, this protein labeling was localized between the nucleus and the Kurloff body, and also on the Kurloff body itself. This data reinforces the hypothesis of de novo synthesis of the Kurloff body.

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PubMed1984

[Effects of a natural estrogen, estradiol, on hemostasis in guinea pigs].

17-beta-estradiol was administered weekly to female guinea-pigs at the dosage of 2-3 mg/kg body weight during 4-6 weeks. Compared to a control population, no significant effect was observed on: recalcification time; thromboelastography; PTT; APTT; Quick one stage prothrombin time; antigenic and active plasma fibrinogen level; antithrombin III level; factor XI level; red and white blood cell count. A significant increase in levels of factor II (+25%), of factor V, of factor XII (+40%) and a decrease in levels of complex VII + X was observed. Values for AT III, factor XII, chronometric and immunologic fibrinogen plasma levels, unknown until now for the guinea-pig, were established.

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PubMed1983

Scanning electron microscopy of pure Kurloff cell suspensions. Observation of an extrusion process.

Scanning electron microscopy has been used to examine suspensions of Kurloff cells, which are present only in guinea pig. The cells are round with a surface characterized by uniformly distributed short stubby microvilli and some ridges. Some cells show one or more pores surrounded by a smooth margin, others a smooth globular expansion about 10 microns in diameter which may correspond to a Kurloff body undergoing exocytosis. The Kurloff body is released into the medium where it can exist freely. The surface of the free body and of the expansion display the same smooth appearance. Although the nature of the Kurloff cell remains unknown, this study provides further information concerning its morphology and describes an extrusion process not observed previously.

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PubMed1983

Lack of estradiol receptor in Kurloff cell cytosol.

The percentage of lymphoid cells containing Kurloff bodies is increased after estrogen treatment. Cytosolic fractions of pure Kurloff cells were incubated with tritiated 17 beta-estradiol. No measurable specific binding was observed under any of the different experimental conditions tested. Kurloff cells do not appear to be a target cell for estrogen.

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PubMed1983

[Increase in the number of Kurloff cells following estrogen stimulation in guinea pigs: demonstrated latency period].

The comparative study between plasma estradiol levels and KURLOFF cell numbers in the blood and some organs of adult, non pregnant female guinea-pigs, leads us to describe a biphasic response of the KURLOFF cells to estrogen stimulation. The first step, a five day lag-phase, is followed by a secondary increase of KURLOFF cell numbers with a peculiarly noticeable storage in the thymus parenchyma.

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PubMed1978

Fibrinogen or its derivatives in the Kurloff cells.

We have investigated the occurrence of fibrinogen or its derivatives in the Kurloff bodies of female guinea pigs by means of immunofluorescence, histochemistry and ultrastructural analysis. The Kurloff bodies are fluorescent after incubation with anti-guinea pig fibrinogen immuno-globulins coupled with fluorescein isothiocyanate. PTAH, Martius scarlet blue, Masson 44--41, Picro-Mallory V stain the Kurloff bodies just as they stain fibrin and fibrinoid. However, the ultrastructure of the central mass of the Kurloff body is finely granular without fibrils. Thus the Kurloff body contains no fibrin but incompletely polymerized fibrinogen derivatives or breakdown products of fibrin.

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PubMed1977

Red cell and white cell counts in adult female guinea-pigs.

We made red cell and white cell counts in an homogeneous sample of more than 250 healthy, non gravid, adult, female guinea-pigs. Up to the present it is the highest number of guinea-pigs on which systematic blood counts have been taken. Each category of cells was studied statistically. Our mean of the red cells (5.03 X 106/mm3) is close to most of the means reported in the literature for both sexes; the distribution apparently follows the Gauss normal distribution. The mean of the white cells that we obtained (11.800/mm3) is greater than those of many authors in both sexes. The total number of lymphocytes and monocytes (6.180/mm3) is larger than that of the granulocytes (4.970/mm3). The mean Kurloff cells is 422/mm3. The distribution curves of the aggregate of white cells and those of the granulocytes, the lymphocytes and monocytes, the Kurloff cells are asymmetrical and spread towards the right; the normality hypothesis is rejected for each of them.

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PubMed1976

The Kurloff cell. Its differentiation in the blood and lymphatic system.

Kurloff cells belong to the group of macrophages as far as ultrastructure, adhesiveness and identification with Kupffer cells (in the case of the liver) are concerned. A characteristic group of features makes it easy to recognize them: PAS reaction, cyanol-blue staining, presence of myelin figures in electron microscopy and attachment to glass-slides. Kurloff cells are thymic and blood cells. They are observed in small numbers in the circulating blood and, in large quantities, in spleen (red pulp), liver (hepatic sinusoids) and lung (septal capillaries). They are absent from lymphatic nodules and from diffuse lymphatic tissues. Morphological and experimental studies indicate that, in spite of some equivocal similarities, Kurloff cells are distinguishable by many criteria from erythrophagocytic cells and from protein-secreting blood cells.

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PubMedDate not supplied

Collagen-associated sulphated proteoglycans. Ultrastructure after formaldehyde-cetylpyridinium chloride fixation.

In the course of an ultrastructural cytochemical study of intracellular sulphated proteoglycans involving the addition of cetylpyridinium chloride in the primary aldehyde fixative, a remarkable ultrastructural preservation of the collagen-associated sulphated proteoglycans was observed. Together with the preservation of their localization among the collagen fibrils (with, for some of them, a 50 nm periodic association with d-bands) and of their native elongated shape, previously observed under similar technical conditions, these stick-shaped and chondroitinase ABC-sensitive proteoglycans exhibited a typical pattern with several dense longitudinal parallel tracks (periodicity: 3-4 nm) not described as yet. Readily observable without high iron diamine-staining, the morphology of these cetylpyridinium chloride-precipitated and collagen-associated polyanions was particularly enhanced after incubation in the diamine solution which ascertained their sulphate content. Such a common ultrastructural organization with parallel tracks for both intracellular (i.e., in eosinophilic polymorphonuclear cells and Kurloff cells) and extracellular CPC-precipitated sulphated proteoglycans could correspond to intrinsic properties of the complexed molecules and could be related to 'double track' proteoglycans observed under other technical conditions in basement membranes.

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