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Biomedical subjects

V Murray

Publications and source records attributed to V Murray.

At least 19 recordsLinked to original sources
PubMed1997

Protein-DNA interactions in the human beta-globin locus control region hypersensitive site-2 as revealed by four nitrogen mustards.

Four nitrogen mustards have been used in this study to examine protein-DNA interactions in intact human cells, specifically at the locus control region hypersensitive site-2 (LCR HS-2) of the human beta-globin locus. Three of these nitrogen mustards are DNA-targeted by attachment of an acridine or amsacrine intercalating chromophore, while the fourth (chlorambucil) is a non-targeted mustard. The ligation-mediated PCR technique was used to determine the sites of damage at base pair resolution on DNA sequencing gels. A densitometric comparison was made between DNA damaged in intact erythroid K562 cells and in purified DNA. The intensity of DNA damage sites in the LCR HS-2 were found to differ significantly between intact K562 cells and purified DNA. At the NF-E2/AP-1 motif, pronounced damage protection was observed in DNA derived from drug treated cells. The nuclear factor- erythroid 2 (NF-E2) protein factor is thought to bind at this NF-E2/AP-1 motif in K562 cells. Other sites of protection and enhancement that corresponded to known transcription factor binding sites were also detected. These nitrogen mustards are therefore very effective compounds for detection of transcription factor binding to DNA in intact cells and are superior to other commonly used agents. The sequence selectivity of the compounds was determined using plasmid DNA and compared to that found in intact cells. The acridine-based nitrogen mustard had a preference for forming adducts at guanine bases, while the two amsacrine-based nitrogen mustards and chlorambucil formed adducts at both guanine and adenine bases.

Aminacrine↗
PubMed1997

Use of an automated sequencer to determine the sequence specificity of DNA damage.

An automated sequencer was used to determine the sequence specificity of DNA damage caused by hedamycin in the plasmid pUC19 using a linear amplification/Taq DNA polymerase method. Previously, manual DNA sequencers have been in widespread use to investigate the sequence specificity of a DNA damaging agent. Manual DNA sequencers are restricted in the length of DNA sequence that can be read at base pair resolution for densitometry. An automated sequencer can greatly expand on the length of analysable DNA sequence. An additional important capability of the automated sequencer, is the ability to quantitate the intensity of damage at each base pair site. Thus we have used the automated sequencer to elucidate the sequence specificity of DNA damage for 300 bp. We have carried out an extended analysis of the sequence specificity of hedamycin DNA damage and found that the sequence 5'-cGt-3', tGt and cGg are preferentially damaged. The sequence specificity of cisplatin was also investigated.

Alkylating Agents↗
PubMed1997

Use of paracetamol for suicide and non-fatal poisoning in the UK and France: are restrictions on availability justified?

OBJECTIVE: To investigate the relationship between the availability of paracetamol and its use for overdose and suicide. DESIGN: Analysis of routinely collected information on time trends for paracetamol suicides, non-fatal overdoses, and sales. SETTING: England and Wales and France. RESULTS: There were strong correlations between trends in paracetamol sales in the UK and trends in non-fatal paracetamol overdose in Oxford between 1976 and 1993 (Spearman's r = 0.86; 95% confidence interval (CI) 0.54, 0.96) and between paracetamol sales and non-fatal overdoses in France between 1974 and 1990 (r = 0.99; 95% CI 0.97, 1.00). Sales figures were also correlated with paracetamol related suicides in both England and Wales, 1983-91 (r = 0.72; 95% CI 0.11, 0.94) and France, 1974-90 (r = 0.79; 95% CI 0.50, 0.92). Similarly strong relationships were observed between trends in non-fatal overdoses and suicide by paracetamol poisoning in England and Wales (r = 0.85; 95% CI 0.61, 0.95) and France (r = 0.79; 95% CI 0.50, 0.92). It is estimated that approximately 32,000 overdoses involving paracetamol occur annually in England and Wales. Fatality rates from paracetamol overdose were four times as high in England and Wales (0.4%, 95% CI 0.38, 0.46) as in France (0.1%, 95% CI 0.06, 0.17). CONCLUSION: Trends towards greater availability of paracetamol are paralleled by increases in its use for both non-fatal overdose and suicide. Paracetamol related morbidity and mortality seem to be less frequent in France where the quantity of paracetamol in a single purchase is limited. Although not conclusive, these data add to a body of evidence which suggests that restrictions in the quantity of paracetamol available as a single purchase in the UK may reduce suicide and liver failure related to paracetamol.

Acetaminophen↗
PubMed1997

Thunderstorm-related asthma--the epidemic of 24/25 June 1994.

BACKGROUND: A large epidemic of asthma occurred following a thunderstorm in southern and central England on 24/25 June 1994. A collaborative study group was formed. OBJECTIVES: To describe the epidemic and the meteorological, aerobiological and other environmental characteristics associated with it. METHODS: Collation of data from the Meteorological Office, the Pollen Research Unit, the Department of the Environment's Automatic Urban Network, from health surveillance by the Department of Health and the National Poisons Unit, from clinical experience in general practice and hospitals, and from an immunological study of some of the affected cases from north east London. RESULTS: The thunderstorm was a Mesoscale Convective System, an unusual and large form of storm with several centres and severe wind gusts. It occurred shortly after the peak grass pollen concentration in the London area. A sudden and extensive epidemic occurred within about an hour affecting possibly several thousand patients. Emergency services were stretched but the epidemic did not last long. Cases had high serum levels of IgE antibody to mixed grass pollen. CONCLUSION: This study supports the view that patients with specific IgE to grass pollen are at risk of thunderstorm-related asthma. The details of the causal pathway from storm to asthma attack are not clear. Case-control and time series studies are being carried out.

Adult↗
PubMed1996

Influence of chromatin structure on bleomycin-DNA interactions at base pair resolution in the human beta-globin gene cluster.

The DNA sequence specificity of bleomycin was examined in human cells and in purified genomic DNA. In each case, DNA damage sites were determined at nucleotide resolution in the human single-copy beta-globin promoter and the locus control region (LCR) hypersensitive site 2 (HS-2). Exponential amplification of gene-specific genomic fragments was achieved by ligation-mediated PCR, and labeled reaction products were analyzed directly by sequencing gel electrophoresis. Bleomycin was found to cleave DNA preferentially at GC, GT, and GA dinucleotides. This study represents the first occasion that the sequence specificity of bleomycin has been determined in intact human cells at the single-copy gene level. The intensity of bleomycin damage sites in the LCR HS-2 was found to differ substantially between intact cells and purified DNA at putative transcription factor binding sites. Bleomycin activity was greatly reduced in cells at a tandem NF-E2/AP1 DNA sequence element. This footprint was strongest in K562 cells where the nuclear factor-erythroid 2 (NF-E2) is thought to bind. Protection and enhancement were also observed at other sequence elements in the HS-2 that associate with erythroid-specific and ubiquitous transcription factors. These results suggest that the activity of bleomycin is significantly reduced at the site of protein-DNA interactions in intact cells. This property of bleomycin is extremely useful in genomic "footprinting", where it has significant advantages over other commonly used agents.

Base Composition↗
PubMed1996

Needs for care from a demand led community psychiatric service: a study of patients with major mental illness.

UNLABELLED: OBJECTIVE--To measure needs for care of patients aged 18-65 years with major mental illness. DESIGN: Identification of everyone in one area seen by a health professional within the previous five years because of a psychotic disorder. Interview of a one in three sample of patients and their main carers with the cardinal needs schedule. SETTING--Hamilton, a socially deprived district of Scotland. SUBJECTS--71 subjects were interviewed from the original sample of 263 patients. MAIN OUTCOME MEASURES--"Cardinal problems" in seven clinical and eight social areas of functioning; these are defined as problems requiring action. "Needs"-cardinal problems for which suitable interventions exist but have not been tried recently. RESULTS--High levels of morbidity were found. 30 interviewed patients (42%; 95% confidence interval 31% to 54%) had one or more clinical needs. 35 (49%; 38% to 61%) had one or more social needs. Skills to deal with all but seven needs in the sample were available at the time of investigation. Patients not being seen by the community mental health team were similar in severity and levels of need to those who were on the community team's caseload. Care was unequivocally and severely inadequate for four patients. Shortcomings in service delivery usually arose from failure to monitor some patients at home. Problems were not due to shortage of acute psychiatric beds nor the absence of an elaborate assertive community care team. CONCLUSIONS--Systematic assessment of needs with research instruments can give valuable insights into the successes and failures of community care of people with major mental illness. Most needs could be dealt with in these patients but in our area (and probably most other parts of the United Kingdom) this would entail diversion of resources from people with less severe disorders.

Adult↗
PubMed1996

The influence of linker chain length on the sequence specificity of DNA damage by n-bromoalkylphenanthridinium bromides in plasmid DNA and in intact human cells.

The sequence specificity of DNA damage of n-bromoalkylphenanthridinium bromides, with linker chain lengths (n) of 4,6,8 and 10 methylene groups, was investigated in the plasmid pUC8 and in intact human cells. A linear amplification assay was used to elucidate the DNA sequence specificity of the alkylating agents. In this assay Taq DNA polymerase extends from an oligonucleotide primer up to the damage site and the products run on a DNA sequencing gel to reveal the precise sites of DNA damage. For both the plasmid and cellular experiments, the compound that caused the most damage to DNA was the n=6 compound, followed by (in decreasing order) the n=4, n=8, and n=10 compounds. There were significant differences in the sequence specificity of DNA damage between n-bromoalkylphenanthridinium bromides of different linker chain length; (1) the main sites of damage were at guanines for the n=4,6 and 8 compounds but at guanines and adenines for the n=10 compound; (2) a consensus sequence of 5'-c(a/t)Ggg-3' was obtained for the n=4,6 and 8 compounds but 5'-c(a/c)(G/A)(g/a)-3' for the n=10 compound; (3) runs of consecutive Gs were the major site of damage for the n=4,6 and 8 compounds, but consecutive Gs or consecutive As for the n=10 compound; (4) for damage at single isolated guanines, the most damaged sequences were at 5'-Ga-3' for the n=4 compound but at 5'-Gt-3' for the n=6,8 and 10 compounds. The tandemly repeated alpha RI DNA sequence was the DNA target in intact human K562 cells. In intact human cells, the compounds produced damage with similar DNA sequence selectivity to that found in plasmid DNA. The n=4 and 6 compounds possess marginal anti-tumour activity and these compounds produced the most damage in intact human cells. The n=8 and 10 compounds do not demonstrate significant anti-tumour activity and these compounds resulted in the least damage in cells.

Antineoplastic Agents, Alkylating↗
PubMed1996

Concentration of blood lead and ethnicity in the United Kingdom.

The relation between concentration of blood lead and ethnic background in 779 children was examined with the analytical results from the trace element service at the Medical Toxicology Unit (MTU), Guy's and St Thomas's Hospital Trust for the period 1980-94. The ethnic identity was determined with the first and the second names of the investigated subjects. Of the patients of European origin (European) studied 72.8% v only 50.6% of the children with origins in the Indian subcontinent (Asian) had a concentration of blood lead < 100 micrograms/l. The percentage of subgroups with concentrations above the upper acceptable limit of 200 micrograms/l was significantly higher in Asian subjects (European 5% v Asian 26.5%), with the most pronounced difference in those with concentrations of blood lead of 500 micrograms/l (European 0.8% v Asian 10.5%). This study shows that a correlation exists between Asian ethnic background and concentration of blood lead in children. Factors such as cultural habits-for example, use of traditional remedies, cosmetics, diet- and socioeconomic status, may have contributed to this results.

Asia↗
PubMed1995

The interaction of hedamycin and DC92-B in a sequence selective manner with DNA in intact human cells.

The sequence specificity of the pluramycin antibiotics hedamycin and DC92-B, was established in intact human cells using a linear amplification system. In this system an oligonucleotide primer is extended by Taq DNA polymerase up to a damage site. The products are run on a DNA sequencing gel and the damage can be determined to the exact base pair. The human repetitive alpha RI DNA was used as the target DNA sequence for these experiments. It was found that G residues were the main site of adduct formation, for both hedamycin and DC92-B. The sequences 5'-TGT and 5'-CGT were the most intense sites of DNA damage. A comparison of the DNA damage intensity in intact cells and purified DNA revealed that the sequence position of adduct formation was very similar in the two environments. However, a densitometric comparison of the damage intensity in the two environments revealed significant differences. Two regions were found (120 and 130 bp in length) where the damage intensity was relatively lower in intact cells compared to purified DNA. But at the boundaries of these sequences, there were regions (approx. 50-60 bp long) that were relatively more damaged in intact cells compared to purified DNA. One explanation of this phenomenon is the presence of a protecting nucleosome core on each of the 120/130 bp regions and flanking nucleosome linker regions of 50-60 bp. This postulated sequence phasing of the nucleosomes corresponds almost exactly with the major nucleosome phasing found in African green monkey cells. Also the centromere protein B binding site is found in the border region between the nucleosome core and linker DNA regions. Hedamycin and DC92-B produced nearly identical results in this human cell system.

Anthraquinones↗
PubMed1995

Comparison of the sequence selectivity of the DNA-alkylating pluramycin antitumour antibiotics DC92-B and hedamycin.

The sequence selectivity of DNA alkylation by the recently isolated pluramycin antitumour antibiotic DC92-B has been investigated using two methods: a piperidine-induced strand-breaking procedure and a Taq DNA polymerase/linear amplification method. These techniques reveal that guanines are the most reactive sites for alkylation and that the level of adduct formation at these sites is clearly sequence dependent. The highest levels of alkylation occurred at isolated guanines located in 5'-CGT sequences and also at the 5'-G in some 5'-CGG sequences. Isolated guanines in 5'-TGT sequences were also quite reactive. We have also re-examined, in parallel, the sequence selectivity of binding of the structurally-related compound hedamycin: the first known example of a bis(epoxide)-containing, DNA-alkylating pluramycin. Our studies included a more extensive sequence analysis of hedamycin binding than that previously reported and we are able, therefore, to define more precisely the sequence preference. Despite significant differences in the stereochemistry and substitution of their bis(epoxide) sidechains, hedamycin and DC92-B exhibited very similar sequence selectivities in our assays.

Alkylation↗
PubMed1994

Comparison of the sequence specificity of cis-diamminedichloroplatinum (II) damage in guanine- and 7-deazaguanine-containing DNA.

The N7 of guanine is thought to be the primary target for adduct and crosslink formation between cisplatin and DNA. However, reactive sites in DNA other than the N7 of guanine may also participate in the formation of adducts with cisplatin. The possibility that these interactions arise and form DNA polymerase blocking lesions was investigated by primer extension reactions with Taq DNA polymerase. To differentiate between damage produced at relatively weak sites from those formed at the N7 of guanine, a modified DNA template was synthesised with the N7 of guanine replaced with a carbon atom. This was achieved in a PCR designed to incorporate 7-deazaguanine instead of normal guanine. The sequence specificity of cisplatin damage in the modified and unmodified DNA substrates was compared (after linear amplification) by DNA sequencing gel analysis. For concentrations of cisplatin (1 to 5 microM) that induce blocking lesions in normal DNA, no significant damage was observed in the modified DNA. This confirmed that the N7 of guanine is the major site of adduct formation in normal DNA. At higher concentrations of cisplatin (50 microM and 100 microM), lesions were found at AA dinucleotides and other novel sites in the modified DNA. These results indicate that the N7 of guanine is not required in the formation of some cisplatin adducts.

Base Sequence↗