Biomedical subjects

S C Riley

Publications and source records attributed to S C Riley.

66 records · Page 4Linked to original sources

PubMed1989

Altered VH gene segment utilization in the response to phosphorylcholine by aged mice.

Newly generated bone marrow B cell precursors of aged BALB/c mice, stimulated in splenic fragment cultures, display a markedly increased frequency of phosphorylcholine (PC)-responsive cells. This increased frequency is found for both precursors that utilize VHS107, a phenotype common to essentially all PC-specific B cells of young mice, and, surprisingly, for precursors that utilize VH genes other than VHS107. PC-specific hybridomas derived from bone marrow cells of aged mice utilize members of at least three VH gene segment families that have never been observed in PC responses of young mice. The ability of aged but not young mice to generate these unique PC-specific clonotypes may be evidence for constraints on V region utilization during repertoire development in young adults and has important implications for aging-associated changes in immune responsiveness.

Aging↗

PubMed1989

Is protein synthesis necessary for prostaglandin production by guinea-pig endometrium?

The outputs of prostaglandin (PG) F-2 alpha, PGE-2 and 6-keto-PGF-1 alpha from Day-7 and Day-15 guinea-pig endometrium in culture were reduced by the inclusion of actinomycin D, cycloheximide and puromycin in the culture medium, with the output of PGF-2 alpha from Day-15 endometrium being particularly affected during the first 6 h of culture. The intrauterine administration of actinomycin D on Day 10 decreased the outputs of PGF-2 alpha and PGE-2, but not of 6-keto-PGF-1 alpha, from Day-15 endometrium in culture without affecting PG output from Day-15 myometrium in culture. Actinomycin D, cycloheximide and puromycin did not reduce PG output when superfused over the Day-7 and Day-15 guinea-pig uterus in vitro for 20 min, indicating that these compounds do not have a rapid inhibitory effect on endometrial PG synthesis. In fact, they tended to stimulate PG output during this 20-min period, with cycloheximide having a pronounced effect on PGE-2 output. The synthesis of secreted proteins, but not of cellular proteins, was greater by Day-15 than by Day-7 endometrium in culture. Actinomycin D, cycloheximide and puromycin inhibited the synthesis of secreted and cellular proteins by Day-7 and Day-15 endometrium in culture. Protein synthesis and PG synthesis in the endometrium were both inhibited to a greater extent by cycloheximide and puromycin than by actinomycin D. The intrauterine administration of actinomycin D on Day 10 reduced the syntheses of secreted and cellular proteins by Day-15 endometrium in culture. These findings indicate that the endometrial synthesis of PGs, particularly of PGF-2 alpha towards the end of the oestrous cycle, is dependent upon endometrial protein synthesis.

6-Ketoprostaglandin F1 alpha↗

PubMed1987

Effects of oestradiol, progesterone, hydrocortisone and oxytocin on prostaglandin output from the guinea-pig endometrium maintained in tissue culture.

The effects of oestradiol, oxytocin, progesterone and hydrocortisone in vitro on prostaglandin (PG) output from guinea-pig endometrium, removed on days 7 and 15 of the oestrous cycle and maintained in tissue culture for 3 days, have been investigated. Oestradiol (3.7 to 3700 nM) and oxytocin (2 to 200 pM) did not stimulate endometrial PGF2 alpha output, thus not confirming the findings of a previous report (Leaver & Seawright, 1982), nor did they stimulate the outputs of PGE2 and 6-keto-PGF1 alpha. In fact, oestradiol (3700 nM) inhibited the outputs of PGF2 alpha, PGE2 and, to a lesser extent, 6-keto-PGF1 alpha. Progesterone (3.2 to 3200 nM) inhibited the outputs of PGF2 alpha and PGE2; hydrocortisone (2.8 to 2800 nM) had no effect on endometrial PG output. These findings indicate that the inhibitory effect of progesterone on endometrial PG synthesis and release in the guinea-pig is not due to progesterone having a glucocorticoid-like action. Furthermore, progesterone had no effect on 6-keto-PGF1 alpha output, suggesting that the mechanisms controlling endometrial PGI2 synthesis (as reflected by measuring 6-keto-PGF1 alpha) are different from those controlling endometrial PGF2 alpha and PGE2 synthesis.

Animals↗

PubMed1987

Effect of actinomycin D on prostaglandin synthesis by and output from the guinea-pig uterus.

The intra-uterine administration of actinomycin D on Day 10 reduced the output of prostaglandin (PG) F2 alpha (the major PG released) from the Day 15 guinea-pig uterus in vitro by 80 to 85%. PGE2 output was reduced by 50%, while 6-keto-PGF1 alpha output was unaffected. Plasma progesterone levels were high (3 to 15 ng/ml) on Day 15 due to the reduction in uterine PGF2 alpha output. Endometrial PGF2 alpha synthesizing capacity was reduced by 50% by actinomycin D treatment, while endometrial PGE2 and 6-keto-PGF1 alpha synthesizing capacities were unaffected. Oestradiol treatment in vivo did not reverse the inhibitory effects of actinomycin D on uterine PG production. A23187 increased uterine PGF2 alpha, 6-keto-PGF1 alpha and PGE2 outputs irrespective of treatment, indicating that substrate supply was always rate limiting. Actinomycin D inhibited the uterotrophic action of oestradiol indicating that fresh protein synthesis had been inhibited. Overall, this study suggests that increased protein synthesis is involved in stimulating endometrial PGF2 alpha synthesis and release. Previous studies have shown that increases in enzyme activities induced by oestradiol are only secondary events in the stimulation of endometrial PGF2 alpha production. We propose that oestradiol induces the synthesis of a protein ('lipostimulin') which, acting on a progesterone-primed uterus, "switches on" endometrial PGF2 alpha synthesis and release by causing the activation of endometrial phospholipase A2.

6-Ketoprostaglandin F1 alpha↗

PubMed1987

Prostaglandin production by the guinea-pig endometrium: is calcium necessary?

The output of prostaglandin (PG) F2 alpha from guinea-pig endometrium obtained on day 15 of the oestrous cycle and maintained in tissue culture was significantly (P less than 0.05) reduced by the use of Ca2+-depleted medium, EGTA (a Ca2+ chelator), 8-(N,N-diethyl-amino)octyl-3,4,5-trimethoxybenzoate hydrochloride (TMB-8; an intracellular Ca2+ antagonist), trifluoperazine (TFP) and N-(6-aminohexyl)-5-chloro-1-naphthalenesulphonamide (W-7; both calmodulin antagonists). Nifedipine inhibited PGF2 alpha output at a concentration (100 mumol/l) much greater than that usually required to block Ca2+ channels. Verapamil had a small but significant (P less than 0.05) inhibitory effect on PGF2 alpha output at 10-100 mumol/l. The outputs of PGE2 and, to a lesser extent, 6-keto-PGF1 alpha (the hydrated product of PGI2) were also reduced by using Ca2+-depleted medium. EGTA reduced the outputs of PGE2 and 6-keto-PGF1 alpha on day 1 of culture, but stimulated 6-keto-PGF1 alpha output on day 3 of culture. The outputs of PGE2 and 6-keto-PGF1 alpha were increased by TMB-8 (100 mumol/l) on day 3 of culture and by TFP and, to a smaller extent, by W-7 on all 3 days of culture. Nifedipine (100 mumol/l by not 1 or 10 mumol/l) reduced the outputs of PGE2 and 6-keto-PGF1 alpha on all 3 days of culture, whereas verapamil (100 mumol/l but not 1 or 10 mumol/l) increased the outputs of these two prostaglandins on days 2 and 3 of culture.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1986

Preferential expression of variable region heavy chain gene segments by predominant 2,4-dinitrophenyl-specific BALB/c neonatal antibody clonotypes.

The B-cell repertoire in neonatal mice contains predominant clonotypes that are reproducibly expressed at particular times after birth. We have isolated and sequenced heavy and light chain cDNA clones from three 2,4-dinitrophenyl-specific neonatal hybridomas. Two of these hybridomas (TF2-36 and TF5-139) express idiotypes (Ids) that predominate during the first days after birth, and the third hybridoma (TF2-76) expresses an Id that predominates during the second week after birth. The heavy (H) chain variable (V) region of the TF2-76 hybridoma protein is encoded by a member of the 7183 VH family, one of eight families of murine VH genes that have been defined by Brodeur and Riblet [Brodeur, P. H. & Riblet, R. (1984) Eur. J. Immunol. 14, 922-930]. Members of this family have been found to undergo a disproportionately high frequency of rearrangement in fetal and neonatal liver pre-B-cells. Because the 7183 VH family is located close to the H chain joining (J) region gene segments, JH, other workers have proposed that VH rearrangement frequency is related to distance from the JH segments. However, the two earlier-appearing predominant clonotypes expressed by TF2-36 and TF5-139 hybridoma proteins utilize a member of the 36-60 VH family, probably VH 1210.7, which is located distal to the JH gene segments on chromosome 12. Since 20-30% of day 3 dinitrophenyl-specific B cells express either the Id(TF2-36) or the Id(TF5-139), the VH 1210.7 gene must be utilized at high frequency early in development. These results indicate that the utilization of rearranged VH segments is strongly influenced by factors other than distance from JH.

Animals↗

PubMed1986

Synergism of v-myc and v-Ha-ras in the in vitro neoplastic progression of murine lymphoid cells.

Murine bone marrow was either singly or doubly infected with retroviral vectors expressing v-myc (OK10) or v-Ha-ras. The infected bone marrow was cultured in a system that supports the long-term growth of B-lineage lymphoid cells. While the v-myc vector by itself had no apparent effect on lymphoid culture establishment and growth, infection with the v-Ha-ras vector or coinfection with both v-myc and v-Ha-ras vectors led to the appearance of growth-stimulated cell populations. Clonal pre-B-cell lines stably expressing v-Ha-ras alone or both v-myc and v-Ha-ras grew out of these cultures. In comparison with cell lines expressing v-Ha-ras alone, cell lines expressing both v-myc and v-Ha-ras grew to higher densities, had reduced dependence on a feeder layer for growth, and had a marked increase in ability to grow in soft-agar medium. The cell lines expressing both oncogenes were highly tumorigenic in syngeneic animals. These experiments show that the v-myc oncogene in synergy with v-Ha-ras can play a direct role in the in vitro transformation of murine B lymphoid cells.

Animals↗

PubMed1981

Induction of light chain expression in a pre-B cell line by fusion to myeloma cells.

Pre-B cells, the first cells in the B-lymphocyte differentiation pathway which express immunoglobulin, have recently been shown to express cytoplasmic mu heavy chain (H) but not light chain (L). If, as is believed, pre-B cells are the precursors of immature B lymphocytes, which express surface IgM, the differentiation of pre-B cells to immature B lymphocytes must be accompanied by the expression of light chains. In this case, it should be possible for the progeny of a single pre-B cell to express a variety of light chains in association with the same heavy chain. We have tested this hypothesis by hybridizing a pre-B cell line 18-81 expressing only cytoplasmic mu chains with variant myeloma cells which do not express light chains. Hybridization of B-lymphoma cells with myeloma cells usually produces a hybrid with the phenotype of the more differentiated parent. In this case, the fusion resulted in the induction of light chain expression from the 18-81 genes and we have been able to demonstrate that independent hybrids express different light chains, in accordance with the hypothesis that a pre-B cell committed to expression of a single mu heavy chain can generate progeny expressing different slight chains.

Animals↗

PubMed1979

Immune response to the src gene product in mice bearing tumors induced by injection of avian sarcoma virus-transformed mouse cells.

A single subcutaneous injection of 10(7) live cells of the highly tumorigenic avian sarcoma virus (Schmidt-Ruppin strain, subgroup D)-transformed BALB/c line into BALB/c mice resulted in the production of an antiserum specific for the avian sarcoma virus gene product pp60src. All sera taken from mice 3 weeks after injection of tumor cells contained antibodies to pp60src. Immunoprecipitation experiments showed that all sera precipitated pp60src from Schmidt-Ruppin-infected chicken cells, but only a portion of these sera precipitated pp60src from chicken cells infected with other strains of avian sarcoma virus, i.e., Prague and Bratislava-77. Analysis of the cross-reactivity patterns of these antisera demonstrated a minimum of three to four antigenic determinants on pp60src. The findings reported here should facilitate the production of monoclonal antibodies to pp60src, which in turn will provide highly specific probes for further investigations into the structure and function of this protein.

Animals↗

PubMedDate not supplied

Corticotrophin-releasing hormone production by the placenta and fetal membranes.

Maturation of the fetal hypothalamic-pituitary-axis may be an important factor in the stimulation of the onset of parturition. Recent studies have found that corticotrophin-releasing hormone (CRH), the hypothalamic component of this axis is also present in the placenta and the fetal membranes. We review the evidence demonstrating that glucocorticoids stimulate the production of CRH by these tissues towards term, and this is manifest by increases in CRH concentrations in maternal and fetal plasma and in placental extracts, and by increased abundance of CRH mRNA in the placenta. We discuss how CRH secretion by the placenta and fetal membranes is controlled. We hypothesize that CRH may be an important signal in initiating of the onset and maintenance of term labour and may also be a factor in the etiology of premature labour, through stimulation of the fetal HPA axis, and through paracrine/autocrine interactions within the placenta, fetal membranes and decidua.

Corticotropin-Releasing Hormone↗

PubMedDate not supplied

Immunohistochemical localization of insulin-like growth factors (IGFs) and IGF binding proteins -1, -2 and -3 in human placenta and fetal membranes.

Insulin-like growth factor (IGF) I and II are synthesized within the placenta and are believed to play an important role in the regulation of placental growth and endocrine function. IGF bioavailability is determined at a cellular level by several specific binding proteins (IGF BPs), which are widely but selectively distributed in all developing tissues. We have used immunohistochemistry to localize IGF I and II peptides, and IGF BP-1, -2, and -3 in human placentae, fetal membranes and umbilical cord at 6-8 weeks after therapeutic termination and at term after spontaneous delivery. Primary antisera were directed against human IGF I, human IGF BP-1, bovine IGF BP-2, and human IGF BP-3 respectively. Immunoreactive IGF BP-2 was found in association with the syncytiotrophoblast, intermediate trophoblasts of the fetal villi and chorion, amnion and decidua; while weaker staining was seen in some but not all cytotrophoblasts. A similar but less intense staining pattern was observed for IGF BP-1 and IGF peptides in placenta and amnio-chorion. Strong immuno-staining for IGF BP-1 was seen in decidual cells. No immunoreactive IGF BP-3 was found in placenta or membranes. A co-distribution of IGF BP-2, BP-1 and IGF peptides in placenta suggests a role for these IGF BPs in determining the localization of the IGFs for actions on target tissues.

Abortion, Therapeutic↗

PubMedDate not supplied

Matrix metalloproteinases-2 and -9 and their endogenous tissue inhibitors in tissue remodeling after sealing of the fetal membranes in a sheep model of fetoscopic surgery.

OBJECTIVES: We studied collagen plugging of the fetoscopic access site in an in vivo fetal lamb model for fetoscopic surgery and possible role for matrix metalloproteinase (MMP)-2 and -9 and tissue inhibitors (TIMPs). METHODS: Eight ewes had fetoscopic balloon occlusion of the trachea as an experimental treatment for congenital diaphragmatic hernia between days 88 and 99 of gestation (term 145 days) with sampling of amniotic, allantoic, and tracheal fluid. Nonoperated cotwins were used as controls. The fetoscopy port was closed using a collagen plug. Ten days (range 9-12) later, fluids were sampled and plug sites collected for histologic analysis. Activity of MMP-2 (72 kDa, gelatinase A) and MMP-9 (92 kDa, gelatinase B) was determined in the fluids by zymography and secretion of TIMPs (27-30 kDa; TIMP-1, glycosylated TIMP-3 and TIMP-4, 24 kDa; unglycosylated TIMP-3, 21 kDa; TIMP-2) by reverse zymography and quantified by densitometric analysis. RESULTS: No pregnancy was complicated by amniorhexis or preterm labor. At cesarean, normal volumes of amniotic and allantoic fluid were present in all cases. Histology of the plug sites revealed good integration of the collagen plug without complete restoration of membrane integrity. MMP-2, MMP-9, and TIMPs were detected in all fluids. In the operated animals, significantly (P <.05) higher activity of MMP-9 was found in amniotic fluid, with lower concentrations of TIMPs in allantoic fluid (P <.01). Tracheal occlusion was associated with a significant (P <.02) increase in both MMP-2 and -9 in tracheal fluid. CONCLUSION: Collagen plugging of the fetoscopic access port sites in sheep resulted in functionally effective sealing of the fetal membranes. Changes in MMP-2, MMP-9, and TIMPs suggest an active remodeling of both the fetal lung and the fetal membranes.

Amnion↗