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A Farr

Publications and source records attributed to A Farr.

30 records · Page 2Linked to original sources
PubMed1990

Expression of gamma/delta T cell receptors on lymphocytes from the lactating mammary gland.

gamma/delta cells were at least four times more frequent in lactating mouse mammary glands than among T cells of the most proximal lymph nodes. Two-color staining of freshly isolated T cells and a study of clonally expressed gamma/delta receptors on hybridomas further revealed that the mammary gamma/delta population is heterogeneous, including at least three different subsets, among them cells expressing V gamma 5, V gamma 4 together with V delta 4, or none of these V regions.

Animals↗
PubMed1990

Distribution of thymocytes expressing gamma delta receptors in the murine thymus during development.

We have examined the appearance of thymocytes expressing gamma delta TCR within the developing thymus by using immunohistochemical techniques and flow cytometry in conjunction with the mAb 3A10, which recognizes a determinant associated with the constant region of the delta-chain. gamma delta+ Cells were first detected at day 16 of gestation, attained maximal levels at day 17 of gestation, and declined thereafter. By using the Ulex europeus agglutinin to identify medullary epithelial cells in situ, we observed a striking colocalization of gamma delta+ thymocytes and U. europeus agglutinin-positive medullary epithelial cells during late fetal and neonatal periods of development. In the thymuses of adult mice, gamma delta+ thymocytes were scattered throughout cortical and medullary areas of the thymus and most concentrated in the subcapsular areas of the thymus. Ultrastructural immunohistochemistry confirmed the close association between medullary thymic epithelial cells and gamma delta+ thymocytes in the neonatal thymus and also showed that some TCR-gamma delta molecules were patched to areas of contact with medullary epithelial cells. In contrast to the cellular distribution of either CD3 molecules or the TCR-alpha beta, where extensive intracellular labeling of thymocytes has been observed, cytoplasmic accumulation of delta-chain was not detected.

Animals↗
PubMed1990

Nucleolar organiser regions in kidney tumours and xanthogranulomatous pyelonephritis.

The AgNOR argyrophil technique was applied to clear cut examples of renal adenoma (n = 7), clear cell carcinoma (n = 9), and xanthogranulomatous pyelonephritis (n = 5). There was no significant difference between mean AgNOR counts per cell in adenomas and carcinomas, supporting the idea that there is a continuous spectrum of kidney tumours. Xanthogranulomatous pyelonephritis and clear cell carcinoma showed significant differences in mean AgNOR counts per cell, suggesting that the technique may be of use in distinguishing between these conditions, although further cases may need to be examined to confirm this.

Adenocarcinoma↗
PubMed1988

Endocytosis and degradation of murine anti-human CD3 monoclonal antibodies by normal and malignant T-lymphocytes.

Treatment of lymphoid malignancies with monoclonal antibodies (mAbs) and immunoconjugates is a promising new immunotherapeutic approach. However, few published studies have examined in detail the subcellular fate of antibodies following binding to lymphocyte cell surface antigens. In this study, we have investigated the disposition of monoclonal anti-CD3 antibody 64.1 following binding to normal and malignant T-lymphocytes by using cellular radioimmunoassays and immunoperoxidase and immunogold electron microscopy. Anti-CD3 mAbs were predominantly cleared from the cell membrane at 37 degrees C by receptor-mediated endocytosis, although passive shedding of antibody was also observed. Internalized antibody was sequentially transferred from coated pits to receptosomes and eventually to lysosomes. Intralysosomal degradation appeared to be the ultimate fate of internalized radiolabeled mAbs and was followed by exocytosis of free 125I to the culture medium. Ammonium chloride and monensin were potent inhibitors of lysosomal degradation of 125I-anti-CD3 mAbs and caused intracellular trapping of radiolabeled antibodies. The rapid endocytosis, degradation, and exocytosis of antibody observed in these studies elucidate the mechanism of the improved efficacy of anti-CD3 immunoconjugates when used in conjunction with inhibitors of lysosomal action.

Ammonium Chloride↗
PubMed1988

Sea urchin sperm creatine kinase: the flagellar isozyme is a microtubule-associated protein.

Sea urchin sperm contain two isozymes of creatine kinase (CrK) in the sperm head and tail, as termini of a phosphocreatine shuttle to transport energy. The head isozyme is located at the mitochondrion. By using an antibody prepared against denatured flagellar CrK, we now show that the tail isozyme exists along the entire flagellum. This unusual CrK isozyme, of Mr 145 kDa, is a component of the flagellar axoneme as indicated by electron microscopic immunolocalization and cell fractionation. Flagellar CrK specifically reassociated with extracted sperm axonemes as well as with in vitro polymerized sea urchin egg microtubules. Neither sperm mitochondrial CrK nor mammalian muscle CrK bound to axonemes under similar conditions. Thus, although the two sperm isozymes have similar kinetic properties, they differ in affinity for microtubules, a characteristic that may determine the regional differentiation needed for establishing a phosphocreatine shuttle.

Animals↗
PubMed1987

Amplified RNase H activity in Escherichia coli B/r increases sensitivity to ultraviolet radiation.

Strains of E. coli B/r transformed with the plasmid pSK760 were found to be sensitized to inactivation by ultraviolet radiation (UV) and to have elevated levels of RNase H activity. Strains transformed with the carrier vector pBR322 or the plasmid pSK762C derived from pSK760 but with an inactivated rnh gene were not sensitized. UV-inactivation data for strains having known defects in DNA repair and transformed with pSK760 suggested an interference by RNase H of postreplication repair: uvrA cells were strongly sensitized, wild-type and uvrA recF cells were moderately sensitized and recA cells were not sensitized; and minimal medium recovery was no longer apparent in sensitized uvrA cells. Biochemical studies showed that post-UV DNA synthesis was sensitized and that the smaller amounts of DNA synthesized after irradiation, while of normal reduced size as indicated by sedimentation position in alkaline sucrose gradients, did not shift to a larger size (more rapidly sedimenting) upon additional incubation. We suggest an excess level of RNase H interferes with reinitiation of DNA synthesis on damaged templates to disturb the normal pattern of daughter strand gaps and thereby to inhibit postreplication repair.

DNA Damage↗
PubMed1980

The role of gap junctions in trophoblastic cell fusion in the guinea-pig placenta.

Fusion of cytotrophoblast cells in the guinea-pig placenta occurs at regions of plasma membrane interdigitation where the cells are attached to one another by complex arrays of gap junctions and desmosomes. Fusion begins at the gap junctions, which are lost in this process. The desmosomes play no obvious part in the fusion mechanism and remain after fusion as sites of attachment of syncytiotrophoblast membrane to itself. It is proposed that a major role of gap junctions in placental development is to bring trophoblast plasma membranes into a close relationship which may act as a starting point for cell fusion.

Animals↗
PubMed1979

The localization and properties of membrane adenosine triphosphatases in the guinea-pig placenta.

The distribution and properties of cytochemically demonstrable phosphatases in the near-term guinea-pig placenta were examined using a strontium capture technique for sodium- and potassium-dependent adenosine triphosphatase (Na+, K+-ATPase) and a lead capture technique for magnesium-dependent adenosine triphosphatase (Mg2+-ATPase). Localizations with the strontium technique in the presence of an alkaline phosphatase inhibitor were mainly on the syncytiotrophoblast plasma membranes; the reaction was potassium-dependent and ouabain-sensitive. Reaction product using the lead capture method was found on both trophoblast and endothelial cell plasma membranes and was independent of magnesium and insensitive to p-hydroxymercuribenzoate (POHMB), an inhibitor of membrane ATPases. However, a very large proportion of this reaction could be blocked by an alkaline phosphatase inhibitor. It is concluded that the strontium capture technique gave a reliable localization for Na+, K+-ATPase. However, the lead capture method mainly demonstrated alkaline phosphatase, and does not offer a useful approach to specific ATPase studies in this particular system.

Adenosine Triphosphatases↗
PubMed1977

Structural features and quantitative age-dependent changes in the intervascular barrier of the guinea-pig haemochorial placenta.

The haemomonochorial placenta of the guinea-pig undergoes several quantitative changes between the 49th and 64th days of gestation, all of which are in such a direction as to increase the efficiency of transplacental transport. The fetal vessels become larger, the maternal vessels increase in surface area by proliferation of microvilli, and the effective mean distance between the two vessel sets decreases. The magnitude of these changes suggests that the efficiency of transport of hydrophilic solutes across the maternal-fetal interface could double, although changes in the number of permeation sites per unit area may modify this relationship. The presence of open intercellular spaces and fenestrations in the fetal endothelium suggests that this layer may not be a major permeability barrier in the guinea-pig, but may create an unstirred layer of extracellular fluid between endothelium and syncytiotrophoblast.

Animals↗