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Biomedical subjects

C R Lovell

Publications and source records attributed to C R Lovell.

At least 19 recordsLinked to original sources
PubMed1991

Purification and properties of a unique flavin-containing chloroperoxidase from the capitellid polychaete Notomastus lobatus.

A unique flavin-containing chloroperoxidase from the marine worm Notomastus lobatus was purified to homogeneity. This enzyme is composed of two dissociable protein moieties, a flavoprotein and a heme protein, in 1:1 molar ratio. The flavoprotein (Mr = 120,000) consists of four identical subunits having Mr of 30,000, and contains FAD. The heme protein (Mr = 54,000) is composed of two copies each of two non-identical subunits (Mr = 15, 500 and 11, 500) and contains ferriheme. The native N. lobatus chloroperoxidase (Mr = 174,000) therefore has a structure of alpha 4 beta 2 gamma 2. Neither the flavoprotein nor the heme protein alone has detectable chloroperoxidase activity but readily associate to form fully active enzyme. This enzyme is capable of oxidizing Cl-, Br-, and I- with optimum pH values of 4.5, 5.0, and 4.5, respectively, at 440 microM H2O2 and has halide-independent catalase activity in the absence of organic substrate. The enzyme can halogenate a wide variety of aromatic compounds, including phenol, from which it produces 4-bromophenol, 2,4-dibromophenol, and 2,4,6-tribromophenol. The same compounds are found in N. lobatus. The N. lobatus chloroperoxidase is the first haloperoxidase to be purified to homogeneity from a marine polychaete, the first reported to contain flavin, and has several unusual physical and catalytic properties. This chloroperoxidase appears to represent a new class of haloperoxidases.

Amino Acids↗
PubMed1991

Dandelion dermatitis.

7 subjects, each giving a history suggesting dandelion dermatitis, were patch tested with extracts of dandelion as well as with other common members of the Compositae and to the sesquiterpene-lactone-mix. All were positive to dandelion extracts but only 2 reacted to the sesquiterpene-lactone-mix. Although the mix is a useful screening test for chrysanthemum dermatitis, it may miss dandelion allergy.

Aged↗
PubMed1991

Design and testing of a functional group-specific DNA probe for the study of natural populations of acetogenic bacteria.

The acetogens, although phylogenetically diverse, can be characterized by their possession of the acetyl coenzyme A (acetyl-CoA) pathway for autotrophic CO2 fixation. The gene encoding formyltetrahydrofolate synthetase, a key enzyme of the acetyl-CoA pathway, was previously cloned from the thermophilic acetogen Clostridium thermoaceticum and has now been tested as a group-specific probe for acetogens. Stable hybrids were formed between the probe and single DNA fragments from eight known acetogens representing six genera. A hybrid was also formed between the probe and a DNA fragment from one sulfate reducer known to be capable of both autotrophic CO2 fixation and acetate catabolism. No such hybrid was formed between the probe and DNA from a homoacetate fermenter not known to use the acetyl-CoA pathway, with two known formyltetrahydrofolate synthetase-producing purine fermenters, or with DNA from 27 other species representing 16 genera of organisms that do not use the acetyl-CoA pathway. DNA purified from cells extracted from horse manure was also screened with the acetogen probe. Six hybrids, indicating at least six detectable acetogen "strains," were observed.

Acetyl Coenzyme A↗
PubMed1990

Primary structure of the thermostable formyltetrahydrofolate synthetase from Clostridium thermoaceticum.

The complete nucleotide sequence of the Clostridium thermoaceticum formyltetrahydrofolate synthetase (FTHFS) was determined and the primary structure of the protein predicted. The gene was 1680 nucleotides long, encoding a protein of 559 amino acid residues with a calculated subunit molecular weight of 59,983. The initiation codon was UUG, with a probable ribosome binding site 11 bases upstream. A putative ATP binding domain was identified. Two Cys residues likely to be involved in subunit aggregation were tentatively identified. No characterization of the tetrahydrofolate (THF) binding domain was possible on the basis of the sequence. A high level of amino acid sequence conservation between the C. thermoaceticum FTHFS and the published sequences of C. acidiurici FTHFS and the FTHFS domains of the Saccharomyces cerevisiae C1-THF synthases was found. Of the 556 residues shared between the two clostridial sequences, 66.4% are identical. If conservative substitutions are allowed, this percentage rises to 75%. Over 47% of the residues shared between the C. thermoaceticum FTHFS and the yeast C1-THF synthases are identical, 57.4% if conservative substitutions are allowed. Hydrophobicity profiles of the C. acidiurici and C. thermoaceticum enzymes were very similar and did not support the idea that large hydrophobic domains play an important role in thermostabilizing the C. thermoaceticum FTHFS.

Amino Acid Sequence↗
PubMed1988

Cloning and expression in Escherichia coli of the Clostridium thermoaceticum gene encoding thermostable formyltetrahydrofolate synthetase.

Formyltetrahydrofolate synthetase (FTHFS) (EC 6.3.4.3), a thermostable protein of four identical subunits from Clostridium thermoaceticum was cloned into Escherichia coli SK1592. The clone (CRL47) contained a 9.5 kb EcoRI fragment of C. thermoaceticum DNA ligated into pBR322. It produced catalytically active, thermostable FTHFS, that was not found in E. coli SK1592 containing native pBR322. The identity of the expressed enzyme was confirmed by specific binding of rabbit polyclonal anti-FTHFS serum produced against C. thermoaceticum FTHFS. The specific activities (mumol.min-1.mg-1) of FTHFS in cell free extracts of CRL47 were 28-89 when assayed at 50 degrees C and pH 8. This was from 3-10-fold higher than in C. thermoaceticum extracts. FTHFS was purified to homogeneity from CRL47. The purified enzyme behaved during electrophoresis and gel chromatography and it had similar specific activity and thermostability as the enzyme purified from C. thermoaceticum.

Cloning, Molecular↗
PubMed1988

Irritant contact dermatitis from diallylglycol carbonate monomer and its prevention.

We report an outbreak of irritant contact dermatitis from diallylglycol carbonate monomer among factory employees making optical plastic lenses. Symptoms lessened after simple preventive methods were introduced. Further upgrading of production methods lessened symptoms still further and also restored the company's economic viability.

Dermatitis, Contact↗
PubMed1987

Elastic fibres in normal and sun-damaged skin: an immunohistochemical study.

Sun-exposed and sun-protected skin obtained at post mortem from the nape of the neck in 14 subjects was immunostained using antisera to elastin, lysozyme, amyloid P component, and the plasma protease inhibitors alpha-I antitrypsin, alpha-I antichymotrypsin and alpha-2 macroglobulin. Both the normal elastic fibres in sun-protected skin, and elastosis in sun-exposed skin were positively immunostained for elastin, lysozyme and amyloid P component. Collagen fibres were unstained. No immunostaining of normal elastic fibres or elastosis in the skin was obtained with antisera to alpha-I antitrypsin, alpha-I antichymotrypsin or alpha-2 macroglobulin. It was concluded that the elastosis in sun-exposed skin does contain elastic fibres. The absence of immunostaining for plasma protease inhibitors probably indicates that the elastic material is mature, and not newly-formed.

Elastic Tissue↗
PubMed1987

Type I and III collagen content and fibre distribution in normal human skin during ageing.

The content of type I and III collagen in normal human skin from subjects of different ages was studied by means of a new high performance liquid chromatography method and by SDS-polyacrylamide gel electrophoresis and scanning electron microscopy. The ratio of types I and III collagen in covered skin remained constant throughout childhood and young adult life and the proportion of type III was shown to be the same as previously reported. However, in the elderly, the proportion of type III collagen in the dermis increased to a variable degree. Scanning electron microscopic examination showed a decrease in the number of collagen fibre bundles with age. Average bundle width varied significantly with age. These results may reflect an impaired synthesis of type I collagen in aged skin.

Adolescent↗
PubMed1987

Prophylactic PUVA and UVB therapy in polymorphic light eruption--a controlled trial.

A double-blind controlled trial of low-dose prophylactic oral psoralen photochemotherapy (PUVA) and ultraviolet-B (UVB) irradiation therapy was undertaken from April to September 1983 in 42 patients with polymorphic light eruption (PLE). Patients were randomly allocated to three groups, PUVA with oral 8-methoxypsoralen (8-MOP), UVB with oral placebo, and control low-dose UVA with oral placebo. The initial dose given to each active treatment group was a third of the predetermined minimal phototoxic or erythema dose, followed three times weekly for 6 weeks by doses incremented by an eighth on each occasion in the PUVA group and by a seventh in the UVB group. Ultraviolet radiation exposure was monitored throughout with polysulphone film lapel badges. Patients recorded their symptoms on a visual analogue scale. Symptoms of rash and itch in patients treated with PUVA and UVB were significantly less affected by increasing exposure to ultraviolet radiation than were these symptoms in control patients.

Clinical Trials as Topic↗
PubMed1986

Photocontact urticaria from chlorpromazine.

Chlorpromazine is well recognized as a cause of delayed photosensitive eczema. A patient illustrated typical features of the phenomenon. Urticarial lesions were also elicited on photopatch testing.

Chlorpromazine↗