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J F Miller

Publications and source records attributed to J F Miller.

At least 235 records · Page 13Linked to original sources
PubMed1985

Prostaglandin H synthase: an example of enzymic symbiosis.

Reaction conditions which promote the heme-dependent peroxidase activity of prostaglandin H synthase appear to stimulate the heme-dependent cyclooxygenase activity also present in the synthase, even though the cyclooxygenase requires hydroperoxide for activity. However, aspirin-treated synthase, which retains only peroxidase activity, inhibited the cyclooxygenase activity of untreated synthase in the manner observed with similar levels of glutathione peroxidase. Any stimulatory effect of the synthase peroxidase on the synthase cyclooxygenase is thus likely to involve an intramolecular mechanism. Participation of peroxidase intermediates (Compounds I and II) in the initiation of a cyclooxygenase free radical chain reaction may provide an intramolecular mechanism for stimulation of the synthase cyclooxygenase by the synthase peroxidase.

Aspirin↗
PubMed1985

Liquid nitrogen storage of cultured T lymphocytes.

The conditions required for storing and recovering IL-2-dependent T cell clones from liquid nitrogen were investigated. For maximum cell recovery, cultured T lymphocytes were precooled at 4 degrees C for 15 min in medium containing 10% DMSO and 20% FCS before storage in liquid nitrogen. This method allowed adequate time for DMSO to penetrate the cells before freezing.

Cell Survival↗
PubMed1985

Glia maturation factor influences recovery from injury in neonatal rat brains.

Newborn rats were injured with a puncture wound in one cerebral hemisphere. Experimental animals were treated with three i.p. injections of Glia Maturation Factor (GMF) at daily intervals starting from the time of injury, whereas control littermates were treated with equivalent amounts of bovine serum albumin. At 25 days old the size of the cerebral cortex at the plane of injury was measured on representative brain sections. In control rats the injured side was 18% smaller than the normal side whereas in GMF-treated animals the difference was only 1%. The results suggest a possible regulatory role of GMF in promoting tissue recovery from brain damage.

Animals↗
PubMed1985

A frameshift mutation at the junction of an IS1 insertion within lacZ restores beta-galactosidase activity via formation of an active lacZ-IS1 fusion protein.

The insertion of IS1 elements into lacZ results in the loss of beta-galactosidase activity, and such insertions exert a severe polar effect on the expression of the distal genes of the operon. In addition to these properties, the mutation lacZ::IS1-MS319 has the unique property of reversion to Lac+ (ts) spontaneously or after treatment with the frameshift mutagen ICR-191; such revertants retain the IS1 element. We have determined that the site of integration of IS1 into lacZ is at position 4338, 18 nucleotides from the end of the sequence encoding the C-terminus of beta-galactosidase. Reversion to Lac+ promoted by ICR-191 results from the loss of a G residue from a GGG sequence located at the junction of lacZ and IS1. As a result an active, but temperature-sensitive, lacZ-IS1 fusion protein is formed containing six amino acids derived from IS1 which replace six amino acids encoded by lacZ. The IS1 element in MS319 is a new member of the iso-IS1 family, which we designate IS1T.

Base Sequence↗
PubMed1985

Mitogenic activity of glia maturation factor. Interaction with insulin and insulin-like growth factor-II.

The mitogenic activity of glia maturation factor (GMF) was tested on sparse-cultured cells. GMF stimulates the growth rate of normal astroblasts and fibroblasts grown in the presence of fetal calf serum (FCS), and raises the saturation density of the cells over what is imposed by the corresponding serum concentrations. GMF has no mitogenic effect in the complete absence of serum. The mitogenicity of GMF is also demonstrable in defined media where certain serum components are present. In particular, GMF in combination with the defined medium N2 partially mimics the proliferative effect of serum alone. Insulin, an ingredient of N2, can substitute for the complete N2 formula. Insulin-like growth factor-II (IGF-II), in turn, can substitute for insulin. The interaction of GMF with insulin or IGF-II can be demonstrated in a sequential manner, suggesting that GMF is a competence factor. Since insulin is required at a concentration well above the physiologic serum level, and must be used at a dose 1000 times higher than IGF-II, we suspected that insulin acts on IGF-II receptors. This was substantiated by the demonstration of IGF-II receptors and the absence of detectable insulin receptors on the astroblasts. The combined effect of IGF-II and GMF mimics the combined effect of 10% FCS and GMF, in both growth rate and saturation density.

Animals↗
PubMed1985

The induction of immunologic tolerance in newborn mice by spleen cells differing in H-2K or H-2D, but not "I-J," genotype.

Newborn mice of various strains belonging to the B10A series of recombinants received injections of spleen cells from adult donors to induce immunologic tolerance to antigens of the major histocompatibility complex (MHC). Donor-host combinations were chosen so as to provide differences at H-2K or H-2D, together with various portions of the Ia region. The experiments were predicated on the hypothesis that differences at "I-J" might be required for activation of suppressor cells--thus for the induction of the tolerant state. Tolerance was assessed both by skin grafting and by enumeration of antiallogeneic cytotoxic T lymphocyte precursors (CTL-P) through in vitro limiting-dilution cloning analysis. Host mice that differed from the donor strain only at H-2D, or at H-2K and H-2I-A, were rendered tolerant just as readily as those that differed at "I-J" plus H-2D or "I-J" plus H-2K and H-2I-A. The hypothesis that "I-J" differences are essential for tolerance induction was thus clearly negated.

Animals↗
PubMed1985

Synthesis and turnover of the putative T-lymphocyte antigen receptor.

Cells of an antigen-specific T-cell clone, A37.4, were treated with the proteolytic enzymes trypsin or pronase to remove the T-cell antigen receptor. Removal of the receptor, analysed by surface labelling and non-reduced/reduced gel electrophoresis, stimulated the cells to synthesize new protein rapidly. New membrane protein was readily detectable within 3 h after reculture, and it was able to interact with antigen-presenting cells, since the T cells could be stimulated to produce interferon. Treatment of cells with metabolic inhibitors demonstrated that there was only a small cytoplasmic pool of protein, and de novo synthesis of mRNA was necessary for quantitative replacement of the membrane protein. The protein also required glycosylation for transport and insertion into the membrane. Despite rapid resynthesis of new receptor, when surface-labelled cells were recultured either with or without antigen-presenting cells, there was not a rapid turnover of the receptor. There was also no evidence of any loss of receptor from the membrane of antigen-stimulated cells or of any shedding of receptor into the culture medium.

Animals↗
PubMed1985

F factor inhibition of conjugal transfer of broad-host-range plasmid RP4: requirement for the protein product of pif operon regulatory gene pifC.

By the use of deletions, point mutations, and gene fusions, we show that the protein product of the F factor pifC gene is responsible for F factor inhibition of plasmid RP4 conjugal transfer. Deletion analysis of pif sequences carried by pSC101-F chimeric plasmids demonstrated that removal of all or part of the pifC coding sequence greatly decreased or abolished the ability of these plasmids to inhibit RP4 transfer. Amber mutations in the pifC gene eliminated inhibition in an Su- host strain but not in and Su+ (supF) host. Plasmids carrying nonpolar pifC mutations did not decrease the efficiency of RP4 transfer when present in trans. Whereas pifC+ plasmids inhibited RP4 transfer, the presence of RP4 in the same cell as F' lac increased F'lac Pif activity approximately 1,000-fold. This effect most likely resulted from the binding of the pifC product to RP4 DNA and concomitant derepression of the F factor pif operon. PifC inhibited trans mobilization of pMS204, a nonconjugative plasmid carrying the RP4 oriT locus, by the RP1 derivative pUB307. pMS204 had no trans effect on pif operon expression, whereas pUB307 increased F'lac Pif expression, as did RP4. Our results suggest that the pifC product inhibits expression of one or more RP4 genes, the products of which are required for conjugal transfer of RP4 and are required in trans for mobilization of nonconjugal RP4 oriT containing plasmids.

Base Sequence↗
PubMed1985

Inspiring hope.

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Adaptation, Psychological↗
PubMed1984

Glia maturation factor promotes proliferation and morphologic expression of rat Schwann cells.

Glia maturation factor (GMF) is an acidic protein with a molecular weight of about 20,000 daltons, found in the adult brain of many species. Previously GMF was observed to stimulate the proliferation and subsequent maturation of rat astroblasts in culture. We investigated the effects of GMF on Schwann cells. Schwann cells were dissociated from rat sciatic nerve and purified by means of antimitotic agents and by selective immunoadsorption of contaminating fibroblasts. Cultured Schwann cells after 3 passages assumed a flat polygonal shape. Exposure of the cells to GMF converted the cells to the elongated, spindle morphology typical of Schwann cells. GMF also stimulated a 7-fold increase in DNA synthesis when compared with control cultures grown in F10 medium containing 5% fetal calf serum. The mitogenic activity of GMF was still detectable at 5 ng protein/ml medium. The maximal effect on DNA synthesis occurred 72 h after the initial exposure to GMF. Although the cells were positive for the Schwann cell marker Ran-1, GMF failed to induce the production of myelin-associated glycolipids (galactocerebroside) and proteins (Po) nor did it induce the astrocytic marker glial fibrillary acidic protein (GFAP). The effects of GMF on Schwann cells extend its biological role beyond the central nervous system.

Animals↗
PubMed1984

Sequential interaction of glia maturation factor with insulin.

Astroblasts in culture proliferated when exposed to glia maturation factor for at least 2 hours and then to insulin, but not when exposed in the reverse order. The sequential relation suggests that glia maturation factor is a competence factor.

Animals↗
PubMed1984

An improved procedure for the isolation of glia maturation factor.

A procedure for the bulk isolation of glia maturation factor (GMF) in high yield and high purity from bovine brains is outlined. The method involves extraction by homogenization and centrifugation, followed by ammonium sulfate precipitation and column chromatography with diethylaminoethyl (DEAE) Sephacel, Sephadex G-75, and hydroxylapatite. The method results in a 10,000-fold purification, a purity exceeding that of previously published procedures, and enables us to handle as much as 2.8 kg brain tissue or eight brains/week. The ability to mass-produce GMF with this method greatly facilitates its biological studies, further purification, and chemical characterization. The isolated GMF shows a molecular weight of 13,000 on Bio-gel P-30 column and an isoelectric point of about 5.4 on isoelectric focusing. The isolated GMF is heat labile and susceptible to papain and ficin but relatively resistant to trypsin, neuraminidase, and endoglycosidase.

Animals↗
PubMed1984

Regulation of the F-factor pif operon: pifO, a site required in cis for autoregulation, titrates the pifC product in trans.

F factor pifC, pifA, and pifB gene expression is subject to negative regulation by the product of the pifC locus (J.F. Miller and M. H. Malamy, J. Bacteriol. 156:338-347, 1983). In this paper, we describe the properties of a new regulatory site in the pif region, pifO, which is required in cis for autoregulation of pif gene expression. Spontaneous pifO mutations were isolated that allow expression of a pifC-lacZ protein fusion in the presence of pifC product in trans. Recombination of these pifO mutations onto F'lac results in increased pifA and pifB activity. Thus, a single regulatory element, pifO, regulates pifC, pifA, and pifB expression in cis. The presence of multiple copies of a fragment from the pif region carrying wild-type pifO sequences (F coordinates 42.9 to 42.43 kilobases) in trans to F'lac results in an increase in pifA and pifB activity as measured by inhibition of T7 plating. When the pifO mutations are recombined onto a plasmid carrying pifO, the resulting recombinants are greatly decreased in the ability to increase F'lac pif expression. These results suggest that increased F'lac pifA and pifB expression caused by pifO sequences in trans is a consequence of titration of pifC product and derepression of the pif operon.

Base Sequence↗
PubMed1984

Disorders of communication: investigating the development of language of mentally retarded children.

Research conducted at the Waisman Center on Mental Retardation and Human Development over the past 10 years documents the multidimensional nature of the development of children's language in retarded and nonretarded populations. Recent advances in research methodology now available for investigating language comprehension and production will allow large-scale indepth studies of the lexical, semantic, syntactic, and pragmatic aspects of the language performance of a variety of retarded populations.

Child↗
PubMed1983

An idiotypic determinant formed by both immunoglobulin constant and variable regions.

Immunoglobulin idiotypes are serologically defined determinants associated with the variable (V) region of antibody molecules (reviewed in refs 1-4). One of the best defined idiotype systems is that borne by the phosphorylcholine (PC)-binding IgA proteins TEPC15 (T15) and HOPC8 (H8). The T15 idiotype, defined by sera raised in A strain mice, or in rabbits, is considered identical to that expressed by the majority of BALB/c anti-PC antibodies. To define the idiotypic determinants (idiotopes) of which the T15 idiotype is comprised, monoclonal anti-T15 antibodies were used here to examine both serum and monoclonal anti-PC antibodies. The latter were found to differ from T15 with respect to the idiotope defined by the monoclonal anti-idiotope antibody, 21A5, in that the '21A5 idiotope' was absent from anti-PC sera; of the monoclonal anti-PC antibodies examined, only those which were both T15+ and of the IgA isotype seemed to express this idiotype fully. This result suggests that not only the V region, but also the constant (C) region, of the immunoglobulin molecule can contribute to the formation of an idiotypic determinant. Isotype-restricted idiotopes may be involved in the regulation of antibody responses of particular classes.

Animals↗
PubMed1983

Fusion of DNA region to murine immunoglobulin heavy chain locus corresponds to plasmacytoma-associated chromosome translocation.

Murine plasmacytomas frequently exhibit a translocation of the distal region of chromosome 15 to the end of chromosome 12, where the immunoglobulin heavy chain locus resides. A candidate for the DNA across the chromosome fusion point is a cloned region of non-immunoglobulin DNA which in most plasmacytomas has recombined near the alpha heavy chain constant region gene. That the incoming DNA, provisionally designated LyR (lymphoid rearranging) DNA, does derive from chromosome 15 is shown here by blot analysis of DNA from two panels of somatic cell hybrids: hybridomas between an AKR T-lymphoma (Tikaut) and CBA mouse cells with a cytogenetically distinctive chromosome 15, and between mouse and Chinese hamster cells. LyR DNA segregated with chromosome 15 in all lines and the results assign LyR to the distal two thirds of that chromosome. This assignment, together with the previously reported high frequency of recombination between LyR and C(alpha) in plasmacytomas and associated alteration of LyR transcription suggests that translocation activates a LyR gene involved in plasmacytoma oncogenesis. Moreover, LyR rearrangement in certain T-lymphomas, such as the Tikaut line examined here, also implicate that gene in oncogenesis of some T-lymphomas.

Animals↗