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Biomedical subjects

M R Young

Publications and source records attributed to M R Young.

At least 127 records · Page 7Linked to original sources
PubMed1990

Expression of acid phosphatase-beta-galactosidase hybrid proteins prevents translocation by depleting a soluble factor.

We have shown that hybrid proteins composed of the yeast repressible acid phosphatase (PHO5) and bacterial beta-galactosidase (lacZ) interfere with secretion of native acid phosphatase (Wolfe, P. B. (1988) J. Biol. Chem. 263, 6908-6915). We now report that PHO5-LacZ hybrid proteins have a more general effect on secretion and prevent translocation of several secreted proteins. Translocation of both the mating pheromone alpha-factor and the vacuolar protease carboxypeptidase Y is partially blocked when PHO5-LacZ hybrids are expressed. Cell fractionation and protease sensitivity indicate that alpha-factor and carboxypeptidase Y accumulate in precursor form on the cytoplasmic surface of the endoplasmic reticulum. Indirect immunofluorescence with antibody directed against beta-galactosidase supports the localization of hybrid proteins to the endoplasmic reticulum. Analysis of the hybrid protein phenotype in vivo and in vitro suggests that the hybrid proteins deplete a soluble factor required for efficient translocation across the endoplasmic reticulum. First, a decrease in the expression of a hybrid protein in vivo decreases its effect on translocation. Second, an in vitro translation/translocation reaction, prepared from a hybrid-bearing strain, is deficient in its ability to translocate prepro-alpha-factor across yeast microsomal membranes. This deficiency is complemented by addition of cytosol prepared from wild type cells. Finally, the hybrid protein phenotype is shown to be independent of the requirement for SSA gene products.

Acid Phosphatase↗
PubMed1990

Myelopoiesis-associated suppressor-cell activity in mice with Lewis lung carcinoma tumors: interferon-gamma plus tumor necrosis factor-alpha synergistically reduce suppressor cell activity.

The myelopoietic stimulation which occurs in mice bearing metastatic Lewis lung carcinoma (LLC-C3) tumors is accompanied by immune suppression and the appearance of myelopoiesis-associated immune suppressor cells in the bone marrow and spleen. Low doses of recombinant murine interferon-gamma (IFN-gamma) plus recombinant human tumor necrosis factor-alpha (TNF-alpha) were used to limit myelopoiesis and, in turn, reduce the presence of myelopoiesis-associated immune suppressor cells in LLC-C3 tumor bearers. Neither IFN-gamma nor TNF-alpha alone had any effect in vitro on the growth of myeloid progenitor cells into colonies or on the suppressive activity of bone-marrow cells from LLC-C3-bearing mice. However, the combination of low doses of IFN-gamma and TNF-alpha synergistically inhibited both the growth of myeloid progenitor cells into colonies and the suppressive activity of bone-marrow cells from tumor-bearers. Similar results were obtained in vivo. When used alone, neither IFN-gamma nor TNF-alpha had any effect on myelopoiesis or on suppressor-cell activity. When combined, IFN-gamma plus TNF-alpha synergistically suppressed myelopoiesis and the presence of immune suppressive cells both in the bone marrow and in the spleen of tumor bearers. T-lymphocyte blastogenic and NK cytotoxic activities of the tumor-bearers were restored only after treatment with both IFN-gamma and TNF-alpha.

Animals↗
PubMed1990

Association of a functional prostaglandin E2-protein kinase A coupling with responsiveness of metastatic Lewis lung carcinoma variants to prostaglandin E2 and to prostaglandin E2-producing nonmetastatic Lewis lung carcinoma variants.

Cloned Lewis lung carcinoma (LLC) variants were used in an in vitro migration model for dissemination, to determine if prostaglandin E2 (PGE2) produced by nonmetastatic LLC cells could directly stimulate dissemination of metastatic LLC cells and to identify an intracellular mechanism for such an effect. The migration of metastatic LLC clones was stimulated not only by exogenous PGE2 but also by nonmetastatic LLC cells, by their production of a migration-stimulatory factor which was sensitive to indomethacin and anti-PGE2 antibodies. Nonmetastatic LLC clones were unresponsive to migration stimulation by PGE2. The results of in vivo metastasis studies were consistent with those of in vitro migration studies. In vivo lung metastasis was increased by PGE2, as well as by nonmetastatic cells when they were either admixed with the metastatic LLC inoculum, irradiated and injected adjacent to the metastatic LLC tumor, or localized in chambers and implanted s.c. into mice given injections of metastatic LLC cells. Indomethacin blocked metastasis stimulation by nonmetastatic cells. The in vitro PGE2 stimulation of metastatic LLC cells appeared to be linked to a cyclic AMP (cAMP) response, since migration could also be stimulated by dibutyryl-cyclic AMP and blockage of a cAMP response with nicotinic acid ablated the PGE2 stimulation of migration. In vivo metastasis could be stimulated by elevation of cAMP with aminophylline. The differential responsiveness of metastatic versus nonmetastatic LLC cells to PGE2 could not be due to PGE2-adenylate cyclase coupling, since PGE2 increased the cAMP levels in cultures of both metastatic and nonmetastatic LLC cells. There was, however, a difference in the cyclic AMP-dependent protein kinase (PKA) response to PGE2, with PKA activity of metastatic LLC being stimulated by PGE2 and by the adenylate cyclase-stimulator forskolin, whereas PKA of nonmetastatic LLC was not stimulated by these cAMP elevators, suggesting a dysfunction in the cAMP-PKA coupling.

Animals↗
PubMed1990

The effects of 16,16-dimethyl PGE2 and phosphodiesterase inhibitors on Con A blastogenic responses and NK cytotoxic activity of mouse spleen cells.

Prostaglandins function as down regulators of immune responses probably by increasing the concentration of intracellular cAMP. Phosphodiesterase inhibitors, which prevent the breakdown of cAMP, also increase the intracellular levels of cAMP. Prostaglandins and phosphodiesterase inhibitors have both been shown to suppress immune responses in vitro. In this study 16,16-dimethyl PGE2 (dm-PGE2), added in vitro, suppressed the mouse spleen cell concanavalin A (Con A) response by 38% and natural killer (NK) activity by 53%. Addition of the phosphodiesterase inhibitors, theophylline, RO20-1724, or dipyridamole, decreased both the Con A response and NK activity by at least an additional 30%. We also demonstrate that treatment with dm-PGE2 and theophylline in vivo is more effective than either compound alone in inhibiting NK activity of both untreated mice and mice treated with polyinosinic-polycytidylic acid. These studies support the hypothesis that the immunosuppressive effect of dm-PGE2 is mediated by cAMP and suggest that treatment with a combination of dm-PGE2 and phosphodiesterase inhibitors can augment this immunosuppressive effect.

16,16-Dimethylprostaglandin E2↗
PubMed1990

Tubular lysosomes and their drug reactivity in cultured resident macrophages and in cell-free medium.

Lysosomes were assessed in normal living resident mouse peritoneal macrophages, using mainly phase-contrast microscopy (PCM), darkfield microscopy (DFM), and fluorescence microscopy (FM) after terminal acridine orange (AO) staining; these procedures avoided dyes during experimentation. After a few hours of culture a variable proportion of the normal spherical lysosomes began to assemble in a linear fashion. Fully formed tubular structures, with appearances generally recognized as characteristic of tubular lysosomes (TL), could be seen by PCM or, after labeling, by FM, at 2-5 days (best usually at 4-5 days). This peak was followed by a reduction, and at 8-10 days most of the TL had disappeared, leaving only spherical lysosomes. Renewal of the medium at this stage was followed by a temporary reappearance of TL, suggesting that the medium was a major factor in their initial development also. Formation of TL was enhanced by chloroquine (Cq), though to a lesser degree than by phorbol ester (PMA); in contrast NH4Cl (like Cq a weakly basic amine) caused their disassembly into spherical lysosomes. Manual disruption of the monolayer macrophages enabled TL to be transferred to a cell-free medium, in which they remained apparently stable for several hours. Two known microtubule depolymerizers caused disassembly of TL in the intact cells, reinforcing the idea that the TL are associated with the cytoplasmic microtubule (MT) system; but these agents were inactive in vitro, suggesting that disorganization of the system was responsible for this change.(ABSTRACT TRUNCATED AT 250 WORDS)

Ammonium Chloride↗
PubMed1990

Modulation of eicosanoid biosynthesis and inhibition of substrate availability for phospholipase A2 by a modified hexose sugar, amiprilose hydrochloride.

The modified hexose sugar, amiprilose HCl [1,2-O-isopropylinine-3-O-3'-(N',N'-dimethylamino-n-propyl)-D-g lucufuranose hydrochloride], has previously been shown to have antiinflammatory activities. The present study assessed whether eicosanoid biosynthesis is regulated by amiprilose HCl and whether the regulation is influenced at the early stage of arachidonate liberation from the phospholipid by phospholipase A2 (PLA2). Secretion of both prostaglandin E2 (PGE2) and leukotriene B4 (LTB4) by peritoneal macrophages and neutrophils from amiprilose HCl-treated mice was reduced with neutrophils being slightly more sensitive to the inhibitory effects. Amiprilose HCl was less effective in vitro at inhibiting PGE2 and LTB4 secretion that it was in vivo. Amiprilose HCl did not have a direct inhibitory effect on the PLA2 enzyme or on secretion of the soluble form of PLA2. In contrast, amiprilose HCl modulated the phospholipid substrate for PLA2 as there was inhibition of label release from [1-14C]-oleic acid-labeled substrate source (i) when labeled E. coli substrate for pure PLA2 had been preincubated with amiprilose HCl, or (ii) when labeled peritoneal cells, which had been preincubated with amiprilose HCl, were used as a substrate source either for pure PLA2 or for their own PLA2. Amiprilose HCl was found to bind to peritoneal cells rapidly, but transiently, with maximal binding occurring within 5 min at 37 degrees C. Thus, amiprilose HCl was shown to be inhibitory to secretion of PGE2 and LTB4, at least in part, by inhibiting the availability of substrate for PLA2.

Animals↗
PubMed1990

Linkage relationship of X-linked juvenile retinoschisis with Xp22.1-p22.3 probes.

Linkage analysis was performed to evaluate the relationship between the locus for X-linked juvenile retinoschisis (RS) and five X-chromosomal markers-RC8 (DXS9), SE3.2L (DXS16), 99-6 (DXS41), D2 (DXS43), and 782 (DXS85)-all mapped to the interval Xp22.1-p22.3. Seven U.S. families with 56 affected males were studied. No recombinants were found between RS and DXS9 with a maximum lod score (Z) of 4.93 at a recombination fraction of zero. Obligate recombinants were found for RS with DXS16, DXS41, DXS43, and DXS85. Multipoint linkage analysis and consideration of recombination events within pedigrees suggest that DXS41 and DXS43, and also DXS41 and DXS16, flank RS and that DXS85 lies outside the interval DXS41-DXS43. Our pedigrees provide no evidence for genetic heterogeneity of RS, with five of our families individually showing evidence of linkage. (Z greater than 2.0) to the least one of these probes from Xp22.1-p22.3.

DNA Probes↗
PubMed1990

Stimulation of immune-suppressive bone marrow cells by colony-stimulating factors.

In previous studies, we demonstrated that immune-suppressive bone marrow cells appeared during a period of myelopoietic stimulation in mice bearing Lewis lung carcinoma (LLC) tumors and could be induced from normal bone marrow cells during 3 days of culture with supernatants of LLC variant cells. We have now shown that the capacity of LLC variants to induce immune suppressor cells was associated with the capacity to produce colony-stimulating factor (CSF) activities. The LLC variants that secreted more CSF activities also produced more bone marrow immune suppressor cell-inducing activity. The induction of immune-suppressive bone marrow cells was dependent on bone marrow cell proliferation because irradiation of bone marrow cells prior to culture with the CSF-containing supernatants blocked induction of suppressor cells. Culture supernatants of WEHI-3 cells and of pokeweed mitogen-stimulated spleen cells, rich sources of interleukin 3 (IL-3) and granulocyte-monocyte-CSF (GM-CSF), as well as recombinant mouse GM-CSF and recombinant mouse IL-3, also stimulated bone marrow suppressor cell activity. The combination of GM-CSF with IL-3 resulted in a synergistic rather than simply an additive induction of bone marrow suppressor cells. Conditioned medium of CSF-1-producing L cells did not induce bone marrow immune suppressor cells. These results suggest that during heightened periods of myelopoiesis, induction of bone marrow-derived immune suppressor cells may be stimulated by CSFs, such as by the singular or combined effects of GM-CSF and IL-3.

Animals↗
PubMed1989

Effects of fish oil and corn oil diets on prostaglandin-dependent and myelopoiesis-associated immune suppressor mechanisms of mice bearing metastatic Lewis lung carcinoma tumors.

The effects of a fish oil diet on the myelopoietic and immunological parameters of normal mice and of mice bearing metastatic Lewis lung carcinoma (LLC-C3) tumors were compared to the effects of a corn oil or a mixed-fat rodent chow diet. This was studied soon after tumor appearance, on Day 17, when immune suppression was mediated by prostaglandin E2 (PGE2)-producing suppressor cells, and late in tumor development, on Day 28 when immune suppression was associated with myelopoiesis and the appearance of bone marrow-derived suppressor cells whose activity was not dependent on PGE2. Feeding a fish oil diet from Days 10 to 17 of tumor growth partially restored splenic T-cell blastogenesis, reduced spleen cell secretion of PGE2, and alleviated splenic suppressor activity. When fed from Days 21 to 28 of tumor growth, a fish oil diet neither restored T-cell blastogenesis nor alleviated suppressor cell activity. The fish oil diet increased the frequency of myeloid progenitor cells in normal mice and in mice bearing small or large tumors. Concurrently, the fish oil diet stimulated the appearance of bone marrow-derived suppressor cells. When administered after the establishment of palpable primary tumors, a fish oil diet also increased the formation of pulmonary lung nodules. In contrast to the fish oil stimulation of myelopoiesis and the associated suppressor cells, feeding a corn oil diet to tumor-bearing mice during Days 21 to 28 after tumor implantation reduced myelopoiesis and the presence of the associated bone marrow suppressor cells. These data show that a fish oil diet can minimize the immune suppression in tumor bearers when suppression is mediated by PGE2-producing suppressor cells, but can also induce myelopoietic stimulation leading to the appearance of bone marrow-derived suppressor cells and increased tumor metastasis.

Animals↗
PubMed1989

Differential induction of hematopoiesis and immune suppressor cells in the bone marrow versus in the spleen by Lewis lung carcinoma variants.

Mice bearing large (greater than or equal to 3 g) metastatic and nonmetastatic Lewis lung carcinoma (LLC) tumors were studied to determine if the tumor variants differentially induced bone marrow versus splenic hematopoiesis and the appearance of hematopoiesis-associated immune suppressor cells. The metastatic LLC-C3 and nonmetastatic LLC-C8 tumors were equal in their stimulatory effects in vivo on both the number of bone marrow myeloid progenitor cells (CFU) and the appearance of bone marrow immune suppressor cells. In contrast, the tumor variants differed in their effects on the spleen, with the metastatic tumors causing a more pronounced increase in the number of nucleated cells and CFU, a reduced blastogenic responsiveness to concanavalin (Con-A), and an increased suppressor cell activity than nonmetastatic LLC-C8 tumors. The splenic suppressor cells of mice bearing large LLC-C3 tumors resembled the bone marrow suppressor cells which we previously described (Young et al.: Cancer Res. 47, 100, 1987) in that they were nonadherent to nylon wool, sensitive to treatment with L-leucine methyl ester, insensitive to treatment with complement and Thy-1.2, MG-1.2, asialo-GM1, or anti-IgM antibodies, and mediated their suppression through a mechanism which was only partially indomethacin sensitive. The stimulatory effects on hematopoiesis and suppressor cells by the LLC variant tumors may have been mediated by the tumor-derived colony stimulating factor (CSF) activities. Bone marrow cell proliferation and colony formation were stimulated in vitro by culture supernatants of metastatic LLC-C3 cells and, to a lesser degree, of nonmetastatic LLC-C8 cells. These colony-stimulating factor (CSF)-containing supernatants also induced normal bone marrow cells to become immune suppressive. In contrast, supernatants of only LLC-C3 cells, and not of LLC-C8 cells, stimulated in vitro growth of splenic CFU from LLC-C3-bearing mice; spleen cells from normal mice and from LLC-C8 bearers were unresponsive to supernatants of the LLC variants. These results suggest that CSF produced by either the metastatic LLC-C3 or the nonmetastatic LLC-C8 tumors could concurrently stimulate bone marrow hematopoiesis and the appearance of bone marrow suppressor cells. However, the metastatic LLC-C3 tumor cells, and not the nonmetastatic LLC-C8 cells, could also cause expansion of progenitor cells and hematopoiesis to the spleen and, consequently, induce the appearance in the spleen of hematopoiesis-associated immune suppressor cells.

Animals↗
PubMed1989

Immune parameters of untrained or exercise-trained rats after exhaustive exercise.

The effect of a single exhaustive swimming exercise bout on immune competence of untrained or exercise-trained female Wistar rats was compared with the competence of control sedentary rats. After the exhaustive exercise bout, the blastogenic response to concanavalin A by spleen cells of untrained rats was extensively suppressed, whereas the response of the trained rats was only marginally suppressed. The suppressed immune competence of the untrained rats after the exhaustive exercise was associated with an increase in immune-suppressive activity of splenic lymphocytes. The macrophages of the untrained rats and of the control sedentary rats were slightly immune suppressive to normal spleen cells through a prostaglandin-dependent mechanism. The addition of prostaglandin E2 (PGE2) to the blastogenesis cultures revealed that the spleen cells of untrained rats were unusually sensitive to the suppressive effects of PGE2. In contrast to the untrained rats, the marginal level of immune suppression in trained rats after the exhaustive exercise was associated with a lesser degree of lymphocyte-suppressive activity, an immune stimulatory activity by the splenic macrophages, and an insensitivity of the splenic lymphocytes to the suppressive effects of PGE2.

Animals↗
PubMed1989

Genetic linkage of Beckwith-Wiedemann syndrome to 11p15.

Beckwith-Wiedemann syndrome (BWS), characterized by multiorgan developmental abnormalities and predisposition to cancer, usually occurs sporadically, but small apparently dominant pedigrees have been described. Since rare patients show varying karyotypic abnormalities on the short arm of chromosome 11, it has been suggested that BWS may be related to the Wilms tumor gene on 11p13 or, alternatively, to growth factor genes on 11p15. We performed genetic linkage analysis on two BWS kindreds, using RFLPs for loci on 11p. BWS was linked to the insulin gene (11p15.5), with an overall maximum lod score of 3.60 (recombination fraction = .00). Linkage to D11S16 (11p13) could be excluded for recombination fractions less than or equal to .03. These results suggest that BWS defines a tumor-predisposition gene on 11p15.

Beckwith-Wiedemann Syndrome↗
PubMed1989

Vasectomy reversal.

A small personal series of vasovasostomies and a review of the literature on this subject are presented. The importance is stressed of good counselling before vasectomy is undertaken in the first place.

Adult↗
PubMed1988

Regulation of tumor-induced myelopoiesis and the associated immune suppressor cells in mice bearing metastatic Lewis lung carcinoma by prostaglandin E2.

The in vitro and in vivo effects of prostaglandin E2 (PGE2) and of its stable analogue, 16,16-dimethyl-PGE2 (dmPGE2), on myelopoiesis and on the myelopoiesis-associated immune suppressor cell activity of mice bearing metastatic variant Lewis lung carcinoma (LLC-C3) tumors are assessed. In vitro studies showed a reduced susceptibility of bone marrow myeloid progenitor cells (CFC) from LLC-C3 tumor bearers versus normal mice to the growth-inhibitory effects of PGE2. When added to cocultures of bone marrow cells with LLC-C3 supernatants, PGE2 lessened the frequency of CFC and slightly reduced the generation of bone marrow immune suppressor cells. In vivo studies showed that 4 daily injections of dmPGE2 into LLC-C3 tumor-bearing mice caused some reduction in femoral bone marrow CFC and had an insignificant effect on bone marrow suppressor cell activity. In contrast to the relative insensitivity of bone marrow cells of tumor bearers to the effects of PGE2, in vitro studies showed that CFC formation by spleen cells of tumor bearers was readily inhibited by PGE2. Likewise, in vivo studies showed that spleen cells of dmPGE2-treated LLC-C3-bearing mice had a reduction in cellularity, CFC, and the level of spontaneous proliferation; a reduction in suppressor cell activity; and an increase in blastogenesis. Thus, short-term dmPGE2 treatment of LLC-C3-bearing mice limited the tumor-induced splenic myelopoiesis and reduced the associated splenic immune suppressor cell activity.

16,16-Dimethylprostaglandin E2↗