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Biomedical subjects

R Crawford

Publications and source records attributed to R Crawford.

At least 91 records · Page 5Linked to original sources
PubMed1990

Steroid hydroxylase gene expression in the ovine fetal adrenal gland following ACTH infusion.

Between 90 and 120 days of gestation (term = 147 +/- 5), when plasma cortisol concentrations in the fetus are at a minimum, levels of mRNA encoding the steroidogenic enzymes 17 alpha-hydroxylase (P-450(17 alpha] and cholesterol side-chain cleavage (P-450scc) are also very low. Over the following 30 days, P-450(17 alpha) and P-450scc gene expression increases concurrent with increasing fetal cortisol concentration. The hypothesis tested in this study was that cortisol biosynthesis is minimal in the period 90-120 days because of insufficient ACTH. Fetuses were cannulated between 98-102 days of gestation. Following recovery, 7 fetuses received 24-h ACTH infusions (12 micrograms/24 h) and 5 fetuses received 24-h vehicle infusions; 4 ACTH-infused and 4-vehicle-infused fetuses were then sacrificed immediately after cessation of the infusion. The other fetuses were left in utero for 3 days prior to sacrifice. Fetal blood samples were analysed for ACTH and cortisol and the adrenals processed for hybridization histochemistry and Northern blot analysis. ACTH, but not vehicle, induced significant increases in the width of the adrenal cortex and in the levels of P-450(17 alpha) and P-450scc mRNA. Concurrently, fetal plasma ACTH and cortisol concentrations also increased significantly. In adrenals from fetuses left in utero for 3 days after cessation of the ACTH infusion, P-450(17 alpha) and P-450scc mRNA levels returned to control levels. Plasma ACTH and cortisol levels also approximated basal values. P-450c21 mRNA levels did not vary significantly at any time with the treatments.(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenal Glands↗
PubMed1989

Clinical value of ultrasonography in the detection and removal of radiolucent foreign bodies.

A series of 39 consecutive patients with a suspected retained foreign body in the hand and in whom standard soft issue radiographs were negative were examined by real-time, high-resolution ultrasound scan. At operation 20 patients had radiolucent foreign bodies (18 wood, 2 thorns) removed. Ultrasound scan correctly localized 19 of the foreign bodies before surgery and failed to detect one. No foreign body was found in 19 patients. Ultrasound scan falsely predicted the presence of a foreign body in two of these cases. High-resolution ultrasound scanning is a sensitive, accurate technique for diagnosing foreign bodies which are otherwise difficult to demonstrate by conventional radiographic techniques, and provides accurate three-dimensional localization of the object which is of value to the surgeon at operation.

Adolescent↗
PubMed1989

Fractures of the hook of the hamate.

Fractures of the hook of the hamate have been infrequently reported in the literature. A high index of suspicion is required if the correct diagnosis is to be established. We report three cases of fractures of the hook of the hamate and postulate a mechanism of injury in sportsmen. Once established, an excision of the hook is usually necessary to resolve the discomfort.

Adult↗
PubMed1989

Tissue distribution and levels of gene expression of three steroid hydroxylases in ovine fetal adrenal glands.

Northern blotting and hybridization histochemistry were used to evaluate the ontogeny and cellular distribution of the mRNAs of the cytochrome P-450 enzymes: cholesterol side-chain cleavage (P-450scc), 17 alpha-hydroxylase (P-450(17 alpha] and 21-hydroxylase (P-450c21) in 40 ovine fetal adrenals from 42 days of gestation until term (151 days). The genes for P-450(17 alpha) and P-450scc were expressed strongly in tissue from young (40-60 days) and old fetuses (120 days to term), but to a very minor degree in 90-120 day fetuses. P-450c21 showed a steady increase throughout gestation. In the morphologically immature an unzoned adrenal of the 40-50 day fetus there was some differentiation in gene expression, all cells containing P-450scc and P-450c21 but a few lacking P-450(17 alpha). Once morphological zonation had occurred (80 days), P-450(17 alpha) was confined to the fasciculata. After 120 days there was a radial maturation pattern of the fasciculata cells morphologically, adult-type cells first appearing at the medullary border. However, P-450(17 alpha) and P-450scc mRNAs were equally well expressed in all sections of the fasciculata. The conclusions were: 1) the previously demonstrated triphasic cortisol biosynthetic capacity of ovine fetal adrenals was correlated with the presence, absence, and reappearance of mRNAs P-450(17 alpha) and P-450scc; 2) morphological appearance of fetal adrenocortical cells and expression of three major steroidogenic enzyme genes were not correlated.

Adrenal Cortex↗
PubMed1987

Porcine relaxin. Gene structure and expression.

A porcine genomic cosmid library was constructed to study the structure and regulation of the porcine relaxin gene. Two overlapping cosmids containing relaxin-specific sequences were isolated, and a 9-kilobase BamHI fragment containing the porcine relaxin gene was sequenced. The sequence derived from these cosmids was used to characterize the relaxin gene transcription unit utilized in the pregnant ovary. Analysis of chromosomal and cosmid DNA has shown that porcine relaxin is encoded by a single copy gene, comprising two exons separated by a 5.5-kilobase intron. The gene contains elements representing two classes of repeated sequences homologous with the human Alu and Kpn families. The transcriptional initiation site of this gene was located by primed extension and direct sequencing of relaxin-specific cDNA. Furthermore, the promoter elements were mapped and sequenced, and transcriptional activity was demonstrated. The promoter contained sequences with homology to regions conserved within retroviral long terminal repeats and within the adenovirus E4 promoter.

Animals↗
PubMed1986

Comparison of ligninase-I and peroxidase-M2 from the white-rot fungus Phanerochaete chrysosporium.

Ligninase-I (Mr 42,000-43,000; carbohydrate, 21%) and peroxidase-M2 (Mr 45,000-47,000; carbohydrate, 17%), two representative, hydrogen peroxide-dependent extracellular enzymes produced by ligninolytic cultures of the white-rot fungus Phanerochaete chrysosporium BKM-F-1767, were purified and their properties compared. Spectroscopic studies showed that both native enzymes are heme proteins containing protoporphyrin IX. EPR spectroscopy indicated that iron ions are coordinated with the enzymes' prosthetic groups as high-spin ferriheme complexes. We confirmed reports of others that the ligninase-hydrogen peroxide complex (activated enzyme) reverts to its native state on addition of dithionite or one of the enzyme's substrates (e.g., veratryl alcohol); however, we found that the peroxidase-M2-hydrogen peroxide complex required Mn2+ ions to accomplish a similar cycle. The peroxidase oxidized Mn2+ to a higher oxidation state, and the oxidized Mn acted as a diffusible catalyst able to oxidize numerous organic substrates. Unlike ligninase-I which is found free extracellularly, peroxidase-M2 appears to be associated closely with the fungal mycelium. In its peroxidatic reactions, ligninase-I oxidizes a variety of nonphenolic and phenolic lignin model compounds. In the presence of Mn2+, peroxidase-M2 oxidizes numerous phenolic compounds, especially syringyl (3,5-dimethoxy-4-hydroxyphenyl) and vinyl side-chain substituted substrates. Also, the peroxidase-Mn2+ system (without hydrogen peroxide) expresses oxidase activity against NADPH, GSH, dithiothreitol, and dihydroxymaleic acid, forming hydrogen peroxide at the expense of oxygen. Both enzymes were believed to play roles in lignin degradation, and these are discussed.

Amino Acids↗
PubMed1986

Transformations of arylpropane lignin model compounds by a lignin peroxidase of the white-rot fungus Phanerochaete chrysosporium.

Various lignin model compounds of the O-arylpropane type were oxidized with purified lignin peroxidase from the white-rot fungus Phanerochaete chrysosporium, and oxidation products were identified by gas-chromatography/mass-spectroscopy procedures. Our results are in accord with the theory that lignin peroxidase catalyzes one-electron oxidations of its substrates with formation of cation radicals, and that these radicals undergo degradative reactions that are predictable from a knowledge of cation radical and oxygen chemistry. Cation radicals formed from O-arylpropane model compounds appeared to undergo the following types of degradative transformations: addition of water to ring-centered radicals, followed by proton loss yielding quinones and alcohols; nucleophilic attack by hydroxy functions on propanoid moieties giving cyclic ketals as intermediates which decompose to yield side chain migration products; transfer of the charge of a radical from a ring to the associated alkyl moiety through an ether bond, with loss of a proton from the latter, forming a new carbon-centered radical. The new alkyl-centered radicals apparently were able to abduct dioxygen to form peroxyl radicals which decomposed giving a variety of oxidation products and probably superoxide anion. Specific examples of the above transformations are presented, and their relevance to lignin degradation is discussed.

Basidiomycota↗
PubMed1985

The structure and biosynthesis of epidermal growth factor precursor.

The structure of mouse submaxillary gland epidermal growth factor (EGF) precursor has been deduced from complementary DNAs. The mRNA is approximately 4800 bases and predicts prepro EGF to be a protein of 1217 amino acid residues (133 X 10 Mr). EGF (53 amino acid residues) is flanked by polypeptides of 188 and 976 residues at its carboxy and amino termini, respectively. The amino terminus of the precursor contains seven cysteine-rich peptides that resemble EGF. Towards the carboxy terminus is a 20-residue hydrophobic membrane spanning domain. The mild portion of the EGF precursor shares a 33% homology with the low density lipoprotein receptor, which extends over 400 amino acid residues. These features suggest that EGF precursor could function as a membrane-bound receptor. RNA dot-blot analysis and in situ hybridization show EGF mRNA to be abundant in the submaxillary gland, kidney and incisor tooth buds. Lower EGF mRNA levels were found in the lactating breast, pancreas, small intestine, ovary, spleen, lung, pituitary and liver. In the kidney EGF mRNA was most abundant in the distal convoluted tubules. Analysis of EGF precursor biosynthesis in organ culture of the submaxillary gland and kidney showed differential processing of the precursor in the two tissues. In the submaxillary gland immunoreactive low molecular weight EGF was produced, but in the kidney the high molecular weight precursor was not processed. In the distal convoluted tubule of the kidney EGF precursor may act as a receptor that is involved in ion transport.

Amino Acids↗
PubMed1984

Relaxin gene expression in human ovaries and the predicted structure of a human preprorelaxin by analysis of cDNA clones.

In earlier studies we identified in a human genomic library a gene (human relaxin gene H1) coding for a relaxin-related peptide. We now have evidence that the human genome possesses an additional relaxin-related gene (designated human relaxin gene H2) which appears to be selectively expressed in the ovary during pregnancy. Nucleotide sequence analysis revealed striking differences in the predicted structures of relaxin encoded by these two genes. Chemical synthesis of biologically active relaxin based on the sequence obtained from ovarian cDNA clones confirmed that the expressed gene (H2) encodes an authentic human relaxin. The expressed gene appears to be transcribed into two different sized mRNAs and preliminary evidence suggests that the mRNA transcripts possess different 3'-untranslated regions. There was no evidence for the expression of human relaxin gene H1 in the ovary and so far it is unclear whether gene H1 is expressed in another tissue or whether it represents a pseudogene. From the sequence data presented here it will now be possible to construct oligonucleotide probes and raise antibodies against synthetic peptides which could then be used to identify sites of relaxin biosynthesis and specifically quantitate the expression from either the H1 or H2 relaxin genes.

Amino Acid Sequence↗
PubMed1984

Cloning and analysis of integrated hepatitis virus sequences from a human hepatoma cell line.

We report here the isolation by molecular cloning and the analysis by heteroduplex and restriction enzyme mapping of seven distinct DNA fragments containing hepatitis B virus (HBV) sequences from genomic DNA of the PLC/PRF/5 human liver carcinoma cell line (the Alexander cell). No intact full-length HBV genomes were present. Three different patterns of organization of HBV fragments were detected. These included two linear fragments without detectable rearrangement, three other HBV fragments with internal deletions, and two HBV fragments containing long inverted duplications. HBsAg sequences are preferentially included in the integrated fragment, whereas the core gene is preferentially eliminated. Several of the integrated HBV fragments might act as templates for the synthesis of functional HBsAg mRNA, whereas only one clone could produce a full core antigen transcript.

Base Sequence↗
PubMed1983

The relationship between delayed hypersensitivity response, nutritional status and clinical outcome in surgical patients referred for nutritional support.

Delayed hypersensitivity responses to recall antigens were measured in 125 surgical patients referred for nutritional assessment and support. On initial testing 57 patients were skin test positive and 68 were anergic each of these patient groups being closely matched in terms of surgical conditions. There was a mortality of 4 in the skin test positive group and 26 in the anergic group. The anergic patients were significantly older and in biochemical and anthropometric terms were in poorer nutritional status than the skin test positive group. Of 33 anergic patients who were repeat tested, 15 remained anergic and 18 converted to a positive response. Conversion from anergy to a positive response was not associated with changes in the measured indices of nutritional status and did not improve clinical outcome. The value of repeat skin testing is therefore in doubt.

Journal Article↗