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Biomedical subjects

J C Houck

Publications and source records attributed to J C Houck.

At least 19 recordsLinked to original sources
PubMed1987

Nuclear peptides from calf liver: large scale isolation and fractionation; control of gene expression in cell-free systems, and inhibition of growth of cells in culture.

DNA and nuclear RNA fractions contain small peptides (mol. wt. 600-1500) attached noncovalently. A large scale isolation procedure was developed for the extraction of such peptides directly from the lysed nuclei. Further purification and fractionation was performed with the chromatography on Sephadex, silica gel and H.P.L.C. C18 reverse phase columns. H.P.L.C. fractionation yielded eleven peaks. The peptides are rich in serine, glycine, alanine and acidic amino acids. They do not contain sulfur-containing amino acids. Only occasionally tyrosine, phenyalanine, histidine, arginine, and very moderate amount of lysine are found. These peptides are active in inhibiting gene expression in cell-free systems and incorporation of labeled thymidine in L 1210 murine leukemic cell culture. Thorough and exhaustive analysis demonstrated that the isolated peptides are not degradative products of histone or nonhistone chromosomal proteins.

Amino Acids↗
PubMed1985

Opposing effects of the polycation hexadimethrine (polybrene) on normal and leukemic lymphocytes.

The polycationic compound hexadimethrine has opposing effects on normal and leukemic murine lymphocytes. This polycation significantly stimulated the DNA-synthetic response of murine spleen cells to alloantigens, whereas, at the same concentration, proliferation of the leukemic cell line, L1210, was inhibited. Other polycations tested did not show this effect. The hexadimethrine had no significant effect on the rejection rate of histoincompatible skin grafts in mice. Low concentrations did inhibit the growth of the L1210 leukemia cells in DBA/2J mice.

Animals↗
PubMed1985

Small peptides bound to polysomal RNA inhibit gene expression in cell-free systems, replication of stimulated lymphocytes and DNA repair in isolated chromatin.

Polysomal poly(A)+-RNA prepared from isolated calf liver polysomes by deproteinization and affinity chromatography on oligo(dT)-Sepharose at pH 6 contains low molecular weight peptides (between 600-1500 daltons) bound noncovalently. These peptides were extracted from the poly(A)+-RNA-peptides complex by precipitation of the nucleic acids with 80% (v/v) ethanol at alkaline pH (9.5) and purified on Sephadex G-25 and G-15 columns. Further fractionation was performed by silica gel chromatography and high performance liquid chromatography (h.p.l.c.). The amino acid composition of the isolated peptidic fraction was compared with similar peptides obtained from rat liver, rabbit reticulocyte and calf thymus polysomes. Effluent (ribosomal) RNA contains only negligible amount of peptides. Isolated polysomal RNA peptides were named "deprimerones" (from Latin "deprimere"), since they have a general depressing effect on gene expression in vitro (Hillar & Przyjemski, 1979). Isolated deprimerones not only inhibit DNA transcription, RNA translation in reconstituted cell-free systems, but also DNA replication by DNA polymerase beta with single- and double-stranded DNA template and synthetic deoxyribonucleotide polymers. The inhibitory effect on replication was correlated with the inhibition of [3H]-deoxyribonucleotide incorporation in isolated chromatin and in stimulated lymphocyte cell cultures. The isolated deprimerones are characterized by similar amino acid compositions in various species.

Amino Acids↗
PubMed1985

Nuclear peptides from calf liver: large scale isolation and fractionation; control of gene expression in cell-free systems, and inhibition of growth of cells in culture.

DNA and nuclear RNA fractions contain small peptides (mol. wt. 600 - 1500) attached noncovalently. A large scale isolation procedure was developed for the extraction of such peptides directly from the lysed nuclei. Further purification and fractionation was performed with the chromatography on Sephadex, silica gel and h.p.l.c. C18 reverse phase columns. H.p.l.c. fractionation yielded eleven peaks. The peptides are rich in serine, glycine, alanine and acidic amino acids. They do not contain sulphur-containing amino acids. Only occasionally tyrosine, phenylalanine, histidine, arginine, and very moderate amount of lysine are found. These peptides are active in inhibiting gene expression in cell-free systems and incorporation of labeled thymidine in L 1210 murine leukemic cell culture. Thorough and exhaustive analysis demonstrated that the isolated peptides are not degradative products of histone or nonhistone chromosomal proteins.

Amino Acids↗
PubMed1983

Role of polypeptide growth factors in normal and abnormal growth.

In the preceding sections we have shown evidence that growth-promoting factors are involved in three basic situations. In normal embryonic development and function of mature organisms, growth factors such as NGF and EGF are of prime importance in supporting the necessary embryonic cell proliferation and the development of specific cell types. Other factors operate on subsets of mature cells during specialized functions such as inflammation. Included in this set would be factors such as CSF/MGF and Interleukin-2. Another basic function of growth factors has been shown to be wound repair and organ regeneration. This includes the well characterized PDGF and FGF as well as the various renotropic factors and liver growth factors. As these factors must operate in mature organisms with many different cell types and similar cell types in many locations, more specificity is needed than in embryonic growth. This has resulted in the organ specific factors such as the renotropins and in the unique delivery system of the PDGF. The recent discovery and characterization of the transforming growth factors has provided a possible connection between embryonic and normal developmental growth and the rapid cellular proliferation characteristic of tumor cells. The TGF not only interacts with receptors for normal growth factors such as EGF but are also detectable in low levels in normal tissue and embryos. The exact relationships between these various factors will have to await the determinations of more amino acid sequences for comparisons. The other tumor-related product, tumor angiogenesis factor, is also found in normal tissue and inflammatory reaction sites.(ABSTRACT TRUNCATED AT 250 WORDS)

Angiogenesis Inducing Agents↗
PubMed1983

Isolation of an effective debriding agent from the stems of pineapple plants.

The stem of the pineapple plant contains, in addition to a number of proteases, particularly bromelain, a non-proteolytic component which is responsible for the complete bridement of experimental burns by an "enzymatic dissection" between the viable native and the non-viable denatured burn tissue. With very little scraping, using a tongue depressor, all of the eschar can be removed and a bed suitable for grafting results. This "Escharase" has a molecular weight of 45,000 daltons and is a trimer made up of three identical subunits weighing 15,000 daltons each; it has an isoelectric point of pH 6.04 and has no hydrolytic enzyme activity against normal protein substrates or various glycosaminoglycan substrates. It can be concentrated by membrane ultrafiltration in a molecular weight range between 30,000 and 50,000 daltons and be purified by isoelectric focusing. The biological activity of the Escharase is not dependent on sulfhydryl groups nor upon the contaminating bromelain activity. The Escharase activity varies enormously from preparation to preparation, but the ultrafiltration procedure tends to concentrate Escharase activity to a fairly constant amount.

Animals↗
PubMed1983

Inhibition of lymphocyte transformation by a factor from Pseudomonas aeruginosa.

Extracts of the bacteria Pseudomonas aeruginosa contain a specific inhibitor of lymphocyte transformation. Considerable purification of this inhibitor was possible by a) smashing the bacteria with glass beads, and b) extracting the soluble components with phosphate buffered saline, c) partial purification with ethanol fractionation, d) ion-exchange column chromatography (DEAE-Sephacel) and e) final purification by elution from Ultrogel. The inhibitor was active at a concentration of approximately 10 ng/ml in inhibiting two-way mixed lymphocyte culture of histoincompatible murine splenic lymphocytes in vitro. The inhibitor was also capable of suppressing the proliferation of the murine leukaemic cell line L1210.

Animals↗
PubMed1982

Inhibition of lymphocyte DNA-synthetic responses by spermine-derived polycations.

The polyamines putrescine, spermidine, and spermine are oxidized by the enzyme diamine oxidase to form the corresponding aldehyde derivatives. These aldehydes have been shown to undergo a variety of spontaneous reactions, some of which result in polycationic addition compounds. We have chemically synthesized some spermine-derived polycations by reaction with the dialdehyde glutaraldehyde followed by reduction of te resulting Schiff base with sodium borohydride. Their migration on ion exchange and gel filtration columns was consistent with the formation of polycations with properties similar to those reported for the spontaneous reaction products. When added to cultures of alloantigen or mitogen stimulated lymphocytes, these polycations were potent inhibitors of the incorporation of tritiated thymidine and blast cell formation. This inhibition was reversible, non-cytotoxic, and only apparent if the polycation was added early in the culture period. The concentration of polycation necessary to achieve 50% inhibition of the lymphocyte response decreased as the cationic nature relative to spermine increased.

Animals↗
PubMed1982

Biological specificity of low molecular weight inhibitors of lymphocyte transformation.

Extracts of calf thymus have been shown to contain a number of inhibitors of lymphocyte transformation. A low molecular weight (600 daltons) anionic inhibitor of lymphocyte transformation has been identified and separated from contaminating polyamines and nucleotides. The active fraction inhibited the DNA synthetic response of murine or human T cells to alloantigens in mixed lymphocyte culture and to T-cell-specific mitogens. It was inactive against stimulation of B lymphocytes and several cultured tumor cell lines.

Animals↗
PubMed1981

Immunoreactive endorphin peptides and prolactin in umbilical vein and maternal blood.

Immunoreactive endorphin peptides (ir EP) and prolactin (PRL) were measured by radioimmunoassay in venous blood from the umbilical cord of 86 neonates, 23 postpartum mothers, and 40 randomly selected blood bank donor control subjects. We also assayed these hormones in serosanguineous placental tissue fluid following delivery. The data suggest both ir EP and PRL are elevated during both processes and that placental chemistry may be implicated in blood levels of these hormones. Some biological and clinical aspects of placental opiates are discussed.

Endorphins↗
PubMed1981

Inhibition of mast-cell degranulation by chemotactic peptides.

Pepstatin and f-methionyl peptides which are potent chemotactic agents for neutrophils were found to inhibit the increase in vascular permeability of rat skin which follows the injection of 48/80, anti-rat IgE serum, or pulmonary permeability factor. These latter compounds are known to act by releasing histamine from mast cells. f-Met-Leu-Phe, which is the most active chemotactically, was also found to be the most active inhibitor.

Animals↗
PubMed1981

Pulmonary polyamine permeability factor.

Acid extracts of calf lung have been found to contain low-molecular-weight factors which increase the permeability of the microcirculation when injected into the skin of rats. These factors, which were present in very low levels in aqueous extracts, were purified by gel filtration and ion-exchange chromatography. High-voltage paper electrophoresis revealed two active compounds with mobilities identical to the polyamines spermine and spermidine. Authentic samples of these compounds were as active in the "blueing" reaction as the isolated compounds. The permeability activity of both the isolated factors and the synthetic ones was inhibited by pepstatin and by pretreatment of the animals with pyrilamine maleate. If the normally low extracellular levels of these polyamines is increased by tissue damage, they could increase vascular permeability within the lung by releasing histamine from adjacent mast cells.

Animals↗
PubMed1981

Abnormal behavior of polyamines on gel filtration: a cautionary note.

The polyamines, spermine and spermidine, have been shown to persist in various tissue extracts despite procedures such as dialysis and ultrafiltration which normally remove such low molecular weight compounds. We have found that polyamines in tissue extracts and the standard compounds alone can migrate as much higher molecular weight compounds on gel filtration under a variety of conditions. Thus, even relatively pure fractions obtained from tissue extracts may be contaminated with, or consist entirely of, polyamines, which are potent inhibitors of cell proliferation under certain conditions.

Chromatography, Gel↗
PubMed1981

Pancreatic beta-endorphin-like polypeptides.

Acid extracts of porcine pancreas acetone powders (but not of other tissues) have been shown to contain material which will react firstly in a radioimmunoassay for beta-endorphin, and secondly, compete with 3H-Naloxone and 3H-enkephalinamide in the radio-receptor assay. This material had a molecular weight of approximately 7,000 as judged by both P-10 and G-50 exclusion chromatography, even in the presence of 4 M urea. The G-50 partially purified and desalted fraction demonstrated a dose-dependent analgesia in mice and also influenced mouse behavior in vivo in a manner analogous to that produced by synthetic human beta-endorphin.

Animals↗
PubMed1981

Low molecular weight inhibitors of lymphocyte transformation.

A variety of factors isolated from bovine thymus have been found to inhibit the transformation of human and mouse lymphocytes. The majority of this activity fractionates as low molecular weight material by ultrafiltration or column chromatography. Three distinct fractions of low molecular weight have been isolated. One fraction contains the polyamines spermine and spermidine. A second fraction contains thymidine or thymidine-like nucleotides. The third fraction appears to be polypeptide in nature, and gives an estimated molecular weight of 500--600, is heat and pH stable, and is easily extracted by solutions containing organic solvents. Preliminary steps in the isolation of this inhibitor are presented, and its relationship to other immunosuppressive and anti-mitotic agents is discussed.

Animals↗