Biomedical subjects

J Brown

Publications and source records attributed to J Brown.

At least 109 records · Page 6Linked to original sources

PubMed2001

Routine breast screening for women aged 65-69: results from evaluation of the demonstration sites.

Routine programme data and specially designed surveys from 3 demonstration sites were analysed to determine the implications of extending the NHS Breast Screening Programme (NHSBSP), to include routine invitations for women up to 69 years. All women aged 65-69 and registered with GPs in these areas received routine invitations for breast screening along with those aged 50-64. Overall uptake was 71% in women aged 65-69 compared with 78% in younger women, but was > or = 90% in both groups who had previously attended within 5 years. Recall rates were lower for older women, but with a higher positive predictive value for cancer. The percentages of invasive cancer in different prognostic categories were similar in the 2 age groups. Older women took no longer to screen than younger women. The costs per woman invited or per woman screened were also similar to those for women aged 50-64, whilst the cost per cancer detected was some 34% lower in older women. Breast screening is as cost effective for women aged 65-69 as for those aged 50-64, with a higher cancer detection rate balancing shorter life expectancy. The proposed extension to the national programme will have considerable workforce implications for the NHSBSP and require additional resources.

Aged↗

PubMed2001

Automated immunomagnetic separation and microarray detection of E. coli O157:H7 from poultry carcass rinse.

We describe the development and application of an electromagnetic flow cell and fluidics system for automated immunomagnetic separation (IMS) of Escherichia coli O157:H7 directly from poultry carcass rinse. We further describe the biochemical coupling of automated sample preparation with nucleic acid microarrays. Both the cell concentration system and microarray detection method did not require cell growth or enrichment from the poultry carcass rinse prior to IMS. Highly porous Ni foam was used to enhance the magnetic field gradient within the flow path, providing a mechanism for immobilizing immunomagnetic particles throughout the fluid rather than the tubing wall. A maximum of 32% recovery efficiency of non-pathogenic E. coli was achieved within the automated system with 6 s cell contact times using commercially available antibodies targeted against the O and K antigens. A 15-min protocol (from sample injection though elution) provided a cell recovery efficiency that was statistically similar to > I h batch captures. O157:H7 cells were reproducibly isolated directly from poultry carcass rinse with 39% recovery efficiency at 10(3) CFU ml(-1) inoculum. Direct plating of washed beads showed positive recovery of O157:H7 directly from poultry carcass rinse at an inoculum of 10 CFU ml(-1). Recovered beads were used for direct polymerase chain reaction (PCR) amplification and microarray detection, with a process-level detection limit (automated cell concentration though microarray detection) of < 10(3)CFU ml(-1) in poultry carcass rinse.

Animals↗

PubMed2001

A role for tryptophan in immune control of chlamydial abortion in sheep.

Tryptophan (Trp) catabolism appears to be an important mechanism for regulation of inflammatory responses, resulting in T-cell tolerance and survival of semi-allogeneic concepti during pregnancy. Trp catabolism can be induced by IFN-gamma, and is therefore an important host defence mechanism against intracellular pathogens. Chlamydophila abortus is a bacterial pathogen that can cause persistent infection in non-pregnant sheep, but invades the placenta and causes abortion in late pregnancy. IFN-gamma was found to control the growth of Chlamydophila abortus in ovine cells in a highly dose-dependent manner. Addition of 200U/ml IFN-gamma eradicated all traces of infection from the cultures, whereas concentrations less than 50U/ml failed to control the growth of the organism, resulting in cell lysis. However, concentrations in the range of 50-100U/ml were found to restrict growth to an extent that a persistent infection was established, allowing survival of the organism in tissue culture for several months. Removal of IFN-gamma resulted in the re-appearance of infectious organisms. Addition of exogenous Trp to the cells treated with 50-100U/ml IFN-gamma prevented the establishment of persistence. These effects in tissue culture are analogous to the persistent infection observed in pregnant sheep prior to abortion. These data suggest that control of C. abortus growth in the periphery is linked to the balance of pro-inflammatory cytokine production and availability of Trp during pregnancy.

Abortion, Veterinary↗

PubMed2001

Continuous spore disruption using radially focused, high-frequency ultrasound.

We report on the development of a novel, continuous-flow, radially focused ultrasonic disruptor capable of lysing Bacillus spores in the absence of added chemical denaturants, enzymes, or microparticles. Greater than 99% disruption was achieved for Bacillus globigii spores and Escherichia coli and Bacillus subtilis vegetative cells with sample residence times of 62, 12, and 12 s, respectively. Microscopic and SEM images indicated that at equivalent power levels, the incidence of cell death or loss of viability typically exceeded the efficiency of (visible) cell lysis. However, semiquantitative PCR showed up to a 1,000-fold increase in intracellular DNA availability from ultrasonically disrupted spores, and liberated DNA was intact and available for subsequent detection.

Bacillus↗

PubMed2001

Fear and frustration--the Liverpool cholera riots of 1832.

Public mistrust in the medical profession is not new. We describe a series of street riots that took place in the city of Liverpool in north-west England in 1832 during a cholera epidemic. The disturbances were directed primarily against the local medical fraternity. The episode is of interest, since the same city recently experienced a similar crisis of confidence between doctors and public. On this occasion the cause was not cholera, but rather the reports from Alder Hey Children's Hospital that organ parts from deceased infants undergoing necropsy had been kept for several years without parental consent.

Attitude to Health↗

PubMed2001

PDSA review.

Explore the source record for details and available documents.

Animals↗

PubMed2001

Parent-offspring coadaptation and the dual genetic control of maternal care.

In many animal species, the amount of care provided by parents is determined through a complex interaction of offspring signals and responses by parents to those signals. As predicted by honest signaling theory, we show that in the burrower bug, Sehirus cinctus, maternal provisioning responds to experimental manipulations of offspring condition. Despite this predicted environmental influence, we find evidence from two cross-foster experiments that variation in maternal care also stems from two distinct genetic sources: variation among offspring in their ability to elicit care and variation among parents in their response to offspring signals. Furthermore, as predicted by maternal-offspring coadaptation theory, offspring signaling is negatively genetically correlated with maternal provisioning.

Adaptation, Physiological↗

PubMed2001

New concepts to improve resolution and sensitivity of molecular cytogenetic diagnostics by multicolor fluorescence in situ hybridization.

BACKGROUND: Routine application of multicolor fluorescence in situ hybridization (M-FISH) technology for molecular cytogenetic diagnostics has been hampered by several technical limitations. First, when using chromosome-specific painting probes, there is a limit in cytogenetic resolution of approximately 2-3 Mb, which can mask hidden structural abnormalities that have a significant clinical effect. Second, using whole chromosome painting probes, intrachromosomal rearrangements cannot be detected and the exact localization of breakpoints is often not possible. METHODS: We suggest the use of multiplex-labeled region or locus- specific probes in combination with an optimal probe design to improve the sensitivity and resolution of the M-FISH technology. To allow the application of this assay in routine diagnostics, we developed a multipurpose image analysis system. RESULTS: goldFISH was applied to the study of cryptic translocations in mental retardation patients and to the study of high-resolution breakpoint mapping in non-small cell lung cancer patients. For an individual with mental retardation, who had an apparently normal karyotype by G-banding, we detected an unbalanced translocation involving chromosomes 2 and 7. CONCLUSIONS: In combination with optimally designed probe kits, goldFISH overcomes most of the present limitations of the M-FISH technology and results in virtually 100% reliability for detecting interchromosomal and intrachromosomal rearrangements.

Automation↗

PubMed2001

Human twinning is not linked to the region of chromosome 4 syntenic with the sheep twinning gene FecB.

The tendency to dizygotic (DZ) twinning is inherited in both humans and sheep, and a fecundity gene in sheep (FecB) maps to sheep chromosome 6, syntenic with human 4q21-25. Our aim was to see whether a gene predisposing to human DZ twinning mapped to this region. DNA was collected from 169 pairs and 17 sets of 3 sisters (trios) from Australia and New Zealand who had each had spontaneous DZ twins, mostly before the age of 35, and from a replication sample of 111 families (92 affected sister pairs) from The Netherlands. Exclusion mapping was carried out after typing 26 markers on chromosome 4, of which 8 spanned the region likely to contain the human homologue of the sheep FecB gene. We used nonparametric affected sib pair methods for linkage analysis [ASPEX 2.2, Hinds and Risch, 1999]. Complete exclusion of linkage (lod < -2) of a gene conferring a relative risk for sibs as low as 1.5 (lambda(s) > 1.5) was obtained for all but the p terminus region on chromosome 4. Exclusion in the syntenic region was stronger, down to lambda(s) = 1.3. We concluded that if there is a gene influencing DZ twinning on chromosome 4, its effect must be minor.

Adult↗

PubMed2001

Over-representation of a germline variant in the gene encoding RET co-receptor GFRalpha-1 but not GFRalpha-2 or GFRalpha-3 in cases with sporadic medullary thyroid carcinoma.

In contrast to the hereditary form of medullary thyroid carcinoma (MTC), little is known about the etiology of sporadic MTC. Somatic gain-of-function mutations in the RET proto-oncogene, encoding a receptor tyrosine kinase, are found in an average of 40% of sporadic MTC. We analysed 31 sporadic MTC for somatic and germline variants in GFRA1, GFRA2 and GFRA3 which encode the co-receptors of RET. Although there were no somatic mutations in any of the three genes, a sequence variant (-193C>G) in the 5'-UTR of GFRA1 was found in 15% of cases. Three patients were heterozygous (het); another three patients homozygous (hom) for the G variant. The G allele was not observed in 31 race-matched normal controls. Hence, the relative frequency of this variant in sporadic MTC cases and controls differed significantly (P<0.05). Since this variant lies in the 5' UTR, likely at the transcriptional start site, we analysed for differential expression of GFRalpha-1 at the transcript and protein levels. At the mRNA level, GFRA1 was over-expressed in tumors harboring the rare variant (P=0.06). The presence of the G polymorphic allele seemed to be associated with increased expression by immunostaining for GFRalpha-1. Interestingly, cytoplasmic staining was stronger in intensity for het patients and nuclear staining predominant in hom cases. In conclusion, mutation analysis of GFRA1, GFRA2 and GFRA3 revealed over-representation of a rare variant in GFRA1 (-193C>G) in the germline of sporadic MTC cases. Our data suggest that the mechanism is related to over-expression of GFRalpha-1 and differential subcellular compartmentalization but the precise mechanism as to how it acts as a low penetrance susceptibility allele for the development of sporadic MTC remains to be elucidated.

Carcinoma, Medullary↗

PubMed2001

MEK kinase activity is not necessary for Raf-1 function.

Raf-1 protein kinase has been identified as an integral component of the Ras/Raf/MEK/ERK signalling pathway in mammals. Activation of Raf-1 is achieved by RAS:GTP binding and other events at the plasma membrane including tyrosine phosphorylation at residues 340/341. We have used gene targeting to generate a 'knockout' of the raf-1 gene in mice as well as a rafFF mutant version of endogenous Raf-1 with Y340FY341F mutations. Raf-1(-/-) mice die in embryogenesis and show vascular defects in the yolk sac and placenta as well as increased apoptosis of embryonic tissues. Cell proliferation is not affected. Raf-1 from cells derived from raf-1(FF/FF) mice has no detectable activity towards MEK in vitro, and yet raf-1(FF/FF) mice survive to adulthood, are fertile and have an apparently normal phenotype. In cells derived from both the raf-1(-/-) and raf-1(FF/FF) mice, ERK activation is normal. These results strongly argue that MEK kinase activity of Raf-1 is not essential for normal mouse development and that Raf-1 plays a key role in preventing apoptosis.

Animals↗

PubMed2001

Misclassification of exposure: coffee as a surrogate for caffeine intake.

This study was conducted to assess the effect of exposure misclassification when coffee is used as a surrogate measure of caffeine exposure. Subjects were randomly selected from the telephone directories of four regional municipalities in southern Ontario, CANADA: Data on daily caffeine intake from foods, beverages, and medications were collected from June to November 1995 through self-administered, mailed questionnaires from 481 men and women aged 30-75 years. Although coffee was the main source of caffeine, cross-tabulations of exposure to coffee by total caffeine intake showed that assessment of coffee alone severely underestimated caffeine intake by at least one exposure level. A hypothetical 10-fold increase in risk was completely obscured when only coffee was used to estimate total caffeine intake. The results of this study suggest that measuring coffee instead of caffeine intake may contribute to a lack of positive findings in studies of coffee as a risk factor for disease occurrence, if in fact caffeine is the exposure of interest. On the other hand, measurement of coffee, tea, and cola soft drink intake in the present study appeared to approximate caffeine intake sufficiently and not affect risk estimates adversely.

Adult↗

PubMed2001

Efficient preparation of natural and synthetic galactosides with a recombinant beta-1,4-galactosyltransferase-/UDP-4'-gal epimerase fusion protein.

The numerous biological roles of LacNAc-based oligosaccharides have led to an increased demand for these structures for biological studies. In this report, an efficient route for the synthesis of beta-galactosides using a bacterial beta-4-galactosyltransferase/-UDP-4'-gal-epimerase fusion protein is described. The lgtB gene from Neisseria meningitidis and the galE gene from Streptococcus thermophilus were fused and cloned into an expression vector pCW. The fusion protein transfers galactose to a variety of different glucose- and glucosamine-containing acceptors, and utilizes either UDP-galactose or UDP-glucose as donor substrates. A crude lysate from Escherichia coli expressing the fusion protein is demonstrated to be sufficient for the efficient preparation of galactosylated oligosaccharides from inexpensive UDP-glucose in a multigram scale. Lysates containing the fusion protein are also found to be useful in the production of more complex oligosaccharides in coupled reaction mixtures, e.g., in the preparation of sialosides from N-acetylglucosamine. Thus, bacterially expressed fusion protein is well suited for the facile and economic preparation of natural oligosaccharides and synthetic derivatives based on the lactosamine core.

Carbohydrate Sequence↗

PubMed2001

Self-reported quality of life of individual cancer patients: concordance of results with disease course and medical records.

PURPOSE: To investigate the applicability of a standard quality of life (QL) questionnaire to individual cancer patients and to explore the potential for impact of QL information on the process of care by comparing at group level the QL results with the medical records. PATIENTS AND METHODS: One hundred fourteen consecutive patients at the oncology clinics at St James's Hospital, Leeds, United Kingdom, completed the European Organization for the Research and Treatment of Cancer (EORTC) Quality of Life Questionnaire (QLQ)-C30 on a touch-screen computer over a 6-month period. The QL results were compared with the corresponding medical records at individual and group level. RESULTS: For individual patients, the serial measurement of QL allowed recognition of patterns over time corresponding to disease course. At group level, a higher proportion of patients reported problems on EORTC QLQ-C30 than were mentioned in the medical records (McNemar paired test, P <.01). Most often clinicians mentioned pain (22% to 39%), and at the initial visit role (66%), and social issues (77%). For the rest of the symptoms and functions, the problems were recorded in between 1% and 25% of the notes, but 20% to 76% of the patients reported QL impairment. Problems that were not recorded in the medical notes tended to be of low severity, with a significant trend observed for pain, fatigue, nausea/vomiting, dyspnea, loss of appetite, and physical function scale (chi(2) test, 11.55 to 34.42, df = 1, P <.001). CONCLUSION: The QL data on individual patients was consistent with the clinical records, thus providing evidence for the validity of these measures in assessment of the individual. The QL profiles had more information on symptoms and particularly on functional issues, such as emotional distress and physical performance.

Disease Progression↗

PubMed2001

Mutation analysis of NTRK2 and NTRK3, encoding 2 tyrosine kinase receptors, in sporadic human medullary thyroid carcinoma reveals novel sequence variants.

Somatic mutations in the proto-oncogene RET are found in 25% to 80% of sporadic medullary thyroid carcinomas (MTCs). The significance of somatic RET mutation in MTC initiation and progression, however, remains unknown. Like RET, TRK is a neurotrophic receptor tyrosine kinase. Immunostaining has shown that only a subset of normal C cells expresses Trk family receptors, but in C-cell hyperplasia, they consistently express NTRK2, with variable expression of NTRK1 and NTRK3. In later stages of MTC, NTRK2 expression was reduced while NTRK3 expression was increased. In the context of these data, we sought to determine whether sequence variants in NTRK2 and NTRK3 are responsible for these differences in protein expression. We determined the genomic structure of NTRK2 and found that it consists of at least 17 exons varying in size from 36 to 306 bp. Mutation analysis of sporadic MTC did not reveal any sequence variants in NTRK2 but did reveal 3 variants in NTRK3, c.573C >T (N191N, exon 5), c.678T > C (N226N, exon 6) and c.1488C > G (A496A, exon 12) occurring among 19 chromosomes (31%), 1 chromosome (2%) and 24 chromosomes (39%), respectively. Corresponding germline also harbored these variants. There was a trend toward excess association of the NTRK3 variant c.1488C > G (A496A) in cases (24/62 chromosomes, 39%) compared to controls (18/62, 29%), but this difference did not reach significance (p > 0.05). The remaining 2 NTRK3 variants occurred with similar frequencies between MTC cases and population-matched controls (19 vs. 17 and 1 vs. 0, p > 0.05). We conclude that sequence variants in NTRK2 and NTRK3 are not likely to be responsible for large differences in expression at the protein level, but we cannot exclude very low penetrance effects.

Carcinoma, Medullary↗

PubMed2001

Affinity of mismatch-binding protein MutS for heteroduplexes containing different mismatches.

We have used bandshift analysis to measure the interaction between the Escherichia coli mismatch-binding protein MutS and synthetic DNA fragments containing all possible DNA mismatches as well as an unpaired T (DeltaT). The order of affinity is found to be DeltaT>GT>GG>AA approximately TT approximately TC>CA>GA>CC>GC. We find that the affinity for GT mismatches is affected by the flanking sequence and decreases in the order G(n)C(n)>(GC)(n)>A(n)T(n)>(AT)(n). Studies with base analogues show good binding to phiT (where phi represents 1',2'-dideoxyribose), but much weaker binding to Gphi.

Adenosine Triphosphatases↗

PubMed2001

Mild head injury, anticoagulants, and risk of intracranial injury.

We studied intracranial damage in patients with mild head injuries who were taking warfarin. Of the 215,785 individuals who visited the Mount Auburn and Beth Israel accident and emergency departments during our study, we identified records for 144 patients by anticoagulation status and computed tomography (CT) imaging. We retrospectively reviewed these patients and ten (7%, 95% CI 3-11) with clinically important injuries on cranial CT. Our findings suggest that patients with head injuries who receive anticoagulants have a similar or greater risk of intracranlal injury to those falling into a previously defined moderate-risk category, invalidating a previous conclusion that CT scanning is unnecessary in such patients.

Aged↗

PubMed2001

PTEN induces apoptosis and cell cycle arrest through phosphoinositol-3-kinase/Akt-dependent and -independent pathways.

The tumour suppressor PTEN inhibits cell growth through multiple mechanisms. We have previously demonstrated that overexpression of PTEN in MCF-7 breast cancer cells causes G(1) arrest followed by cell death, the latter of which is believed to be mediated by the phosphoinositol-3-kinase (PI3K) and Akt/PKB pro-apoptotic pathways. In this present study, we show that culture in the presence of low levels of growth factors increased PTEN-mediated growth suppression through the enhancement of PTEN-induced cell death. The caspase 9-specific inhibitor, ZVAD, blocked PTEN-induced cell death without altering the effect of PTEN on cell cycle distribution. Depending on the level of expression, overexpression of dominant-negative Akt induces more cell death and has less effect on the cell cycle or induces similar or decreased cell death without affecting the cell cycle compared with effects on cell death and the cell cycle when overexpressing PTEN. These observations in sum suggest that, in MCF-7 breast cancer cells, the apoptotic cells induced by the overexpression of PTEN did not derive from the G(1)-arrested cells. Further, the effect of PTEN on cell death is mediated through the PI3K/Akt pathway whereas PTEN-mediated cell cycle arrests are through PI3K/Akt-dependent and -independent pathways.

Amino Acid Chloromethyl Ketones↗