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Biomedical subjects

C J Bruton

Publications and source records attributed to C J Bruton.

At least 19 recordsLinked to original sources
PubMed1992

Quantitative differences in the deposition of beta A4 protein in the sulci and gyri of frontal and temporal isocortex in Alzheimer's disease.

The distribution of beta-amyloid protein (beta A4) in the frontal and temporal isocortex of 14 Alzheimer's disease brains was examined using a combination of immunohistochemistry and computer image analysis. The area of cortex covered by beta A4 deposits was determined and expressed as a percentage of the total cortical grey matter area in each field of interest. Significantly more beta A4 was found in the grey matter of the sulci as compared to that of the gyral crests in both the frontal and the temporal lobes (P less than 0.05). Furthermore, in each case, greater quantities of beta A4 were observed in the frontal rather than the temporal lobes. This apparent differential vulnerability is likely to reflect underlying anatomical connections or perhaps differences in cell packing density and appears to strengthen the case for an anatomical basis for the spread of the disease pathology.

Alzheimer Disease↗
PubMed1991

Phage vectors that allow monitoring of transcription of secondary metabolism genes in Streptomyces.

We describe a bacteriophage phi C31-based system that permits the transcriptional fusion of the convenient reporter gene xylE to chromosomally located promoters in Streptomyces hosts. Applicability of the system to genes for secondary metabolism is demonstrated in an experiment showing that transcription of genes for actinorhodin production in Streptomyces coelicolor A3(2) depends on a transfer RNA gene (bldA) for the rare UUA codon. Two other phi C31::xylE vectors are described that allow detection of promoter activity away from their natural location, either at single copy in a prophage or during lytic infections in plaques.

Anthraquinones↗
PubMed1990

Schizophrenia and the brain: a prospective clinico-neuropathological study.

The neuropathological results from a prospective, systematically assessed, series of 56 schizophrenic patients and 56 age- and sex-matched normal controls have been presented. When compared with the normal controls, the brains of the schizophrenic subjects showed a significant reduction in brain weight and brain length with a concomitant increase in ventricular size. (All findings relate to measurements made after formalin fixation). In addition, the brains of the schizophrenic patients contained significantly more non-specific focal pathology and fibrillary gliosis than the controls. After exclusion of cases with moderate and severe Alzheimer-type change, cerebro-vascular disease and all forms of focal pathology, the structural brain changes (i.e. decrease in brain weight and brain length) continued to distinguish the schizophrenia group from the controls. Furthermore, an analysis of the clinical data showed that the structural brain changes were correlated in the schizophrenic patients with a measurement of pre-morbid function. The findings and their possible aetiological implications have been discussed.

Adult↗
PubMed1990

Discovery of an insertion sequence, IS116, from Streptomyces clavuligerus and its relatedness to other transposable elements from actinomycetes.

We have identified an insertion sequence, IS116, present in Streptomyces clavuligerus at one copy per genome. The element was discovered as a 1.4 kb insertion into the multicopy plasmid pIJ702 after propagation in S. clavuligerus. The nucleotide sequence of IS116 and the flanking sequences from pIJ702 have been determined. The junctions with pIJ702 show no target site duplication and there are no inverted repeats at the ends of the element. One putative coding open reading frame of 1197 bp was identified which would code for a protein product of 399 amino acids. This protein resembles deduced integrase/transposase proteins specified by three other transposable elements of actinomycetes: IS110 and the mini-circle from Streptomyces coelicolor A3(2), and--most particularly--IS900 of Mycobacterium paratuberculosis. Two regions that are relatively conserved among these gene products show features found in similar positions in many reverse transcriptases. IS116 and IS900 are also closely similar in their general organization and (apparently) in their insertion site specificity, whereas IS110 and the mini-circle are quite different in these features.

Actinomycetales↗
PubMed1990

Notes from the graveyard: neuropathology and schizophrenia.

Schizophrenia is commonly regarded as a 'functional' psychosis, the implication being that the delusions, hallucinations and cognitive impairment characteristic of the disease have no organic basis. This view is due in no small way to the failure of pathologists to find convincing pathological changes associated with the disease in the first seven decades of the century. Over the last 10 years things have changed considerably. Recent CT and MRI scan studies have provided convincing evidence of significant ventricular enlargement in the brains of schizophrenics and post-mortem studies have shown that schizophrenic brains are about 6% lighter than controls and have a reduced volume and reduced antero-posterior length. Planimetric studies on post-mortem material and a recent MRI study show that medial temporal lobe structures (parahippocampal gyrus, hippocampus and amygdala) are preferentially affected. Although other brain regions (e.g. cingulate gyrus, frontal cortex) also show alterations they appear to be 'downstream' from the regions primarily affected. Morphological studies show that there is a loss of neurons from medial temporal lobe structures and indicate irregularities in their cytoarchitectonic arrangement. The alterations in structure are not associated with degenerative, inflammatory, or abnormal vascular processes. There has been much debate as to the possible causes of the structural changes and whether they are limited to particular 'types' or sub-groups of schizophrenics. At present it seems simpler to suppose that all schizophrenics have a degree of structural abnormality which may differ in degree but not in kind. It has been proposed that the changes in brain structure in schizophrenia are the result of an anomaly of brain development. In the last year CT and MRI studies have shown that ventricular enlargement precedes clinical symptoms and is not progressive. These studies support the developmental interpretation. Future studies will need to focus on (a) the mechanisms (probably genetic) which can cause such developmental anomalies, (b) the neurochemical perturbations occurring as a result of such anomalies and (c) how both relate to clinical symptoms.

Brain↗
PubMed1989

The developmental fate of S. coelicolor hyphae depends upon a gene product homologous with the motility sigma factor of B. subtilis.

In the mycelial prokaryote S. coelicolor, whiG is a gene dispensable for growth but needed for the earliest stages of spore formation in aerial hyphae. Nucleotide sequencing indicates that whiG encodes an RNA polymerase sigma factor highly similar to the motility sigma factor (sigma 28) of B. subtilis. High copy number of an intact whiG gene caused sporulation in vegetative hyphae that are usually fated to lyse without sporulating. However, the introduction of many copies of a sigma 28-dependent promoter from B. subtilis into S. coelicolor reduced sporulation, suggesting partial sequestration of the whiG gene product by the foreign promoter sequences. We propose that the level of whiG sigma factor is crucial in determining the developmental fate of hyphae.

Amino Acid Sequence↗
PubMed1989

Brain amino acid concentrations and Ca2+-dependent release in intractable depression assessed antemortem.

The concentrations of 3 putative neurotransmitters (glutamate, aspartate and gamma-aminobutyrate), 4 related amino acids and 5 non-transmitter-related amino acids have been measured in neurosurgical samples (frontal cortex) from patients with intractable depression and controls. In addition, the glutamate receptor agonist 2-amino-4-sulpho-butanoic acid (homocysteic acid) has been identified in human brain and measured in these samples. There were no changes in the concentrations of amino acids in depressed patients compared to control with the exception of aspartic and homocysteic acids which were elevated in a sub-group of patients with depression compared to control. The Ca2+-dependent release (K+-stimulated) of putative neurotransmitters has been demonstrated for the first time from brain tissue of depressed patients. Glutamate release was unaltered from the control value. Aspartate values showed unexplained variability but it's release and that of gamma-aminobutyrate were elevated in some depressed subjects. These results do not support the hypothesis of reduced amino acid function in depressive illness.

Aged↗
PubMed1989

Schizophrenia as an anomaly of development of cerebral asymmetry. A postmortem study and a proposal concerning the genetic basis of the disease.

Schizophrenia is associated with structural changes (eg, a mild degree of ventricular enlargement) in the brain, although whether these precede onset of illness or progress with episodes is not established. In a postmortem study, we find that ventricular enlargement affects the posterior and particularly the temporal horn of the lateral cerebral ventricle. By comparison with controls and with patients suffering from Alzheimer-type dementia (in which there is also temporal horn enlargement), the change is highly significantly selective to the left hemisphere. This deviation was not accompanied by an increase in glial cell number (examined chemically by assay of diazepam-binding inhibitor immunoreactivity and microscopically by density of staining with the Holzer technique). The findings are consistent with the view that schizophrenia is a disorder of the genetic mechanisms that control the development of cerebral asymmetry.

Alzheimer Disease↗
PubMed1989

The cerebral vasculature in dementia pugilistica.

The brains of 22 ex-boxers were examined histologically to determine the frequency of recent or old haemorrhage. Four boxers had died from an acute intracerebral bleed, usually soon after a boxing bout. Seven of the other 18 showed evidence of previous perivascular haemorrhage, as detected by Perls' ferrocyanide test for iron, and a similar number showed minor degrees of meningeal or subpial siderosis, consistent with previous meningeal bleeding; cerebellar siderosis was present in six cases. Seventeen of the 22 boxers showed evidence of recent or past haemorrhage. Control material showed an incidence of 11% for perivascular iron deposition and only 4% for minor degrees of meningeal siderosis.

Aged↗
PubMed1987

Nucleotide sequence of IS110, an insertion sequence of Streptomyces coelicolor A3(2).

The nucleotide sequences of the Streptomyces transposable element IS110 and its insertion site in the DNA of a derivative of the temperate phage luminal diameter C31 were determined. The element is inserted about 460 bp from the right-hand end of luminal diameter C31 DNA, in a region of apparently non-coding DNA. The target site (in a run of seven C residues) is within an 11 bp sequence homologous with one end of IS110. The inserted element is flanked by runs of 11 and 15 C residues which form part of more extensive regions of homology between the left and right junction regions. Imperfect inverted repeats (10 matches out of 15 bp) are present near (but not at) the ends of IS110. The whole IS110 element contains about 1550 bp of which 71% are G-C bp. One major potentially protein-coding region (ORF 1215) was detected, of 1215 bp, the product of which, a presumptively soluble protein of MR 43,563, was not overtly related to any entry in a protein sequence database. A smaller open reading frame (ORF 330) was tentatively identified in the opposite strand of the ORF 1215 region.

Amino Acid Sequence↗
PubMed1987

The isolation of a peptide from the catalytic domain of Bacillus stearothermophilus tryptophyl-tRNA synthetase. The interaction of Brown MX-5BR with tyrosyl-tRNA synthetase.

Tryptophyl-tRNA synthetase is irreversibly inactivated by Procion Brown MX-5BR with an apparent dissociation constant (KD) of 8.8 microM and maximum rate of inactivation k3 0.192 s-1. The specificity of the interaction is supported by two previously reported observations. Firstly, Brown MX-5BR inactivation of tryptophyl-tRNA synthetase is inhibited by substrates, and secondly, the animated derivative of Brown MX-5BR is a competitive inhibitor of tryptophyl-tRNA synthetase with a Ki of 2 X 10(-4) M with respect to both tryptophan and ATP. Tryptic digestion of the dye-affinity-labelled enzyme and subsequent resolution of the peptides by h.p.l.c. yielded one major dye-peptide peak. Amino acid sequence analysis resulted in the identification of the dye-binding domain centred on lysine-178. Tyrosyl-tRNA synthetase is also inactivated by Procion Brown MX-5BR, and this inactivation is prevented by ATP but not by tyrosine. The interaction of tyrosyl-tRNA synthetase with hydroxylated Brown MX-5BR exhibited non-competitive kinetics with respect to the amino acid-binding site and competitive kinetics against ATP with a Ki of 6 X 10(-6) M.

Amino Acid Sequence↗
PubMed1987

The glucose kinase gene of Streptomyces coelicolor and its use in selecting spontaneous deletions for desired regions of the genome.

A number of deletions in the glucose kinase (glk) region of the Streptomyces coelicolor chromosome were found among spontaneous glk mutants. The deletions were identified by probing Southern blots of chromosomal DNA from glk mutants with cloned glk DNA. The deletions ranged in size from 0.3 kb to greater than 2.9 kb. When cloned glk DNA was introduced on a phi C31 phage vector into a glk mutant that contained a deletion of the entire homologous chromosomal glk region, glucose kinase activity was detected in extracts of these cells. The entire coding information for at least a subunit of glucose kinase is therefore present on the cloned glk DNA. The 0.3 kb glk chromosomal deletion was used to demonstrate that transfer of chromosomal glk mutations on to the phi C31::glk phage could occur by recombination in vivo. Since glk mutations frequently arise from deletion events, a method was devised for inserting the cloned glk DNA at sites in the chromosome for which cloned DNA is available, and thus facilitating the isolation of deletions in those DNA regions. phi C31::glk vectors containing a deletion of the phage att site cannot lysogenize S. coelicolor recipients containing a deletion of the glk chromosomal gene unless these phages contain S. coelicolor chromosomal DNA. In such lysogens, the glk gene becomes integrated into the chromosome by homologous recombination directed by the chromosomal insert on the phage DNA. In appropriate selective conditions, mutants which contain deletions of the glk gene that extend into the adjacent host DNA can be easily isolated. This method was used to insert glk into the methylenomycin biosynthetic genes, and isolate derivatives with deletions of host DNA from within the prophage into the adjacent host DNA. Phenotypic and Southern blot analysis of the deletions showed that there are no genes essential for methylenomycin biosynthesis for at least 13 kb to the left of a region concerned with negative regulation of methylenomycin biosynthesis. Many of the deletions also removed part of the phi C31 prophage.

Chromosome Deletion↗
PubMed1986

Properties of in vitro recombinant derivatives of pJV1, a multi-copy plasmid from Streptomyces phaeochromogenes.

The 10.8 kb plasmid pJV1, isolated from Streptomyces phaeochromogenes, has a high copy number (about 150) and a broad host range among Streptomyces spp. Several pJV1 derivatives carrying the thiostrepton resistance gene (tsr) of S. azureus were made. One derivative, pWOR191, was shown to promote its own transfer and to mobilize chromosomal markers in S. lividans. Another derivative, pWOR109, was non-transmissible. Deletion in vitro of a segment of pWOR109 gave pWOR120 (5.6 kb), which has single BamHI and Bg/II sites shown to be capable of accepting 'foreign' DNA such as a previously cloned S. antibioticus DNA fragment encoding tyrosinase, giving vectors (pWOR125, pWOR126) with properties resembling the well-established multicopy vector pIJ702. Shuttle vectors capable of functioning in both S. lividans and Escherichia coli were also constructed. The region of pJV1 essential for replication and maintenance was localized to a 2.5 kb segment. Stable maintenance of pWOR109 and pWOR120 was observed in the presence of derivatives of pIJ101, the progenitor of pIJ702.

Chromosomes, Bacterial↗
PubMed1985

Resistance, regulatory and production genes for the antibiotic methylenomycin are clustered.

At least 17 kb of DNA from the large unisolatable Streptomyces coelicolor A3(2) plasmid SCP1 are concerned with methylenomycin biosynthesis. Mutational cloning analysis, using insert-directed integration of att site deleted phage vectors into an SCP1-containing host, provided evidence of two large transcription units, of at least 6.6 kb and 9.5 kb. At the leftmost apparent end of the larger (left-hand) transcription unit is a region apparently involved in negative regulation of methylenomycin biosynthesis: when fragments from this region were used to direct phage integration, marked overproduction of methylenomycin resulted. The methylenomycin resistance determinant is located at the rightmost end of this same transcription unit. Hybridisation analysis with 13 kb of the cloned mmy region showed that it was closely similar to a segment of pSV1, a plasmid that specifies methylenomycin biosynthesis in S. violaceus-ruber SANK 95570.

Anti-Bacterial Agents↗
PubMed1985

Physical and genetic analysis of IS110, a transposable element of Streptomyces coelicolor A3(2).

On at least three independent occasions a 1.6 kb segment of Streptomyces coelicolor DNA was detected in apparently the same location in an attP-deleted derivative of the temperate phage phiC31 that carried a selectable viomycin resistance gene. This sequence (termed IS110) allowed integration of the phage (giving viomycin-resistant transductants) at homologous sequences (detected by Southern hybridisation) at several locations in the S. coelicolor genome. The inserted prophages facilitated genetic mapping of two IS110 copies in the chromosomal linkage map. A third copy did not exhibit simple segregation with chromosomal markers, and there appeared to be a frequent DNA rearrangement close to this copy. Some variation in the number of copies of IS110 and their location has taken place in the pedigree of S. coelicolor derivatives. IS110 did not hybridise to any known S. coelicolor plasmid, nor to any of several other IS-like elements previously described in other Streptomyces plasmids or phages. It hybridised strongly to DNA from only a small minority of other Streptomyces species and was absent from S. lividans, a close relative of S. coelicolor.

Bacteriophages↗
PubMed1985

New derivatives of the Streptomyces temperate phage phi C31 useful for the cloning and functional analysis of Streptomyces DNA.

The thiostrepton resistance gene (tsr) of Streptomyces azureus, and a synthetic oligonucleotide adapter sequence, were introduced into the DNA of attP-site-deleted phage phi C31-based cloning vectors. The DNA of two of the new derivatives, KC515 and KC516, contains single sites for the enzymes BamHI, BglII, PstI, PvuII, SstI (two sites close together) and XhoI, available for the insertion of DNA of up to 4 kb. The two vectors also contain a cloned, promoterless viomycin phosphotransferase gene (vph) from Streptomyces vinaceus. When an internal segment of the Streptomyces coelicolor glycerol (gyl) operon was inserted at the appropriate position and in the correct orientation next to vph, it could bring about in vivo recombination leading to fusion of vph of the chromosomally located gyl operon, resulting in glycerol-regulated expression of viomycin resistance. Two other new phi C31 derivatives, KC505 and KC518, are PstI and BamHI replacement vectors, respectively, for 2-8-kb DNA fragments, and allow simple screening for the presence of inserted DNA.

Bacteriophages↗
PubMed1984

The glycerol utilization operon of Streptomyces coelicolor: genetic mapping of gyl mutations and the analysis of cloned gylDNA.

Glycerol-3-phosphate dehydrogenase (gylB) mutations (which cause glycerol sensitivity), and presumed glycerol kinase (gylA) and/or regulatory mutations eliminating both glycerol-3-phosphate dehydrogenase and glycerol kinase activities, map close to the argA locus of Streptomyces coelicolor A3(2). Using the plasmid vector pIJ702 and restriction enzymes BglII and SstI, extensively overlapping S. coelicolor DNA fragments of 2.74 kb and 2.84 kb were isolated, either of which could restore the wild-type phenotype to gylB and some gylA mutants. Genetic and biochemical analyses of mutants carrying the cloned gyl DNA suggested that a functional gyl promoter had not been cloned, and that restoration of the Gyl+ phenotype was achieved by recombination between the cloned and chromosomal gyl DNA sequences. After subcloning parts of this DNA into the phage vector phi C31 KC400, "gene disruption" analysis was carried out, which confirmed the absence of the gyl promoter, and indicated that a polycistronic mRNA traverses gylA and then gylB.

Chromosomes, Bacterial↗