Biomedical subjects

J Charlton

Publications and source records attributed to J Charlton.

At least 19 recordsLinked to original sources

PubMed2001

The furry gene of Drosophila is important for maintaining the integrity of cellular extensions during morphogenesis.

The Drosophila imaginal cells that produce epidermal hairs, the shafts of sensory bristles and the lateral extensions of the arista are attractive model systems for studying the morphogenesis of polarized cell extensions. We now report the identification and characterization of furry, an essential Drosophila gene that is involved in maintaining the integrity of these cellular extensions during morphogenesis. Mutations in furry result in the formation of branched arista laterals, branched bristles and a strong multiple hair cell phenotype that consists of clusters of epidermal hairs and branched hairs. By following the morphogenesis of arista laterals in pupae, we have determined that the branched laterals are due to the splitting of individual laterals during elongation. In genetic mosaics furry was found to act cell autonomously in the wing. The phenotypes of double mutant cells argue that furry functions independently of the frizzled planar polarity pathway and that it probably functions in the same pathway as the tricornered gene. We used a P-element insertion allele as a tag to clone the furry gene and found it to be a large and complicated gene that encodes a pair of large conserved proteins of unknown biochemical function.

Amino Acid Sequence↗

PubMed2000

Cell size and the morphogenesis of wing hairs in Drosophila.

Almost all epidermal cells on the Drosophila wing produce a single cuticular hair. This is formed in the pupae from a microvillus-like cell projection called the prehair. Previous experiments have shown the existence of two mechanisms that ensure that only a single hair is made. One is the restriction of prehair initiation to a small subregion of the cell by the action of the frizzled tissue polarity pathway. The second is a system that ensures the integrity of the prehair. Mutations and drugs that inhibit the actin cytoskeleton lead to the splitting of a single prehair into multiple smaller hairs. We report that large polyploid cells produce multiple hairs both because they form multiple independent prehair initiation centers and because the larger than normal hairs these cells produce have a tendency to split. We show that reducing cell size by starvation partially suppresses the phenotype seen in polyploid cells and that increasing apical cell surface area by mechanical stretching also results in the formation of multiple prehair initiation centers. We also show that the frizzled tissue polarity pathway is functional in large polyploid cells even if it is unable to restrict prehair initiation to a small region of the cell. We conclude that both of these cellular systems are limited in their ability to scale to accommodate larger cell size.

Animals↗

PubMed2000

The domineering non-autonomy of frizzled and van Gogh clones in the Drosophila wing is a consequence of a disruption in local signaling.

The frizzled (fz) gene is required for the development of distally pointing hairs on the Drosophila wing. It has been suggested that fz is needed for the propagation of a signal along the proximal distal axis of the wing. The directional domineering non-autonomy of fz clones could be a consequence of a failure in the propagation of this signal. We have tested this hypothesis in two ways. In one set of experiments we used the domineering non-autonomy of fz and Vang Gogh (Vang) clones to assess the direction of planar polarity signaling in the wing. prickle (pk) mutations alter wing hair polarity in a cell autonomous way, so pk cannot be altering a global polarity signal. However, we found that pk mutations altered the direction of the domineering non-autonomy of fz and Vang clones, arguing that this domineering non-autonomy is not due to an alteration in a global signal. In a second series of experiments we ablated cells in the pupal wing. We found that a lack of cells that could be propagating a long-range signal did not alter hair polarity. We suggest that fz and Vang clones result in altered levels of a locally acting signal and the domineering non-autonomy results from wild-type cells responding to this abnormal signal.

Alleles↗

PubMed2000

Families, groups and clusters of local and health authorities: revised for authorities in 1999.

This is the second of two articles describing the revision of The ONS classification of local and health authorities of Great Britain to take account of area changes in the 1990's. It presents local authorities in Great Britain as at April 1999 in terms of Families, Groups and Clusters, based on 37 socio-economic and demographic variables from the 1991 Census. Health authorities are presented in terms of Families and Groups only, based on the same variables. The previous article (in Population Trends 98) presented, for each local and health authority, up to four other authorities to which it is 'most similar'.

Adolescent↗

PubMed1999

Densely methylated sequences that are preferentially localized at telomere-proximal regions of human chromosomes.

We have constructed a library of densely methylated DNA sequences from human blood DNA by selecting fragments with a high affinity for a methyl-CpG binding domain (MBD) column. PCR analysis of the library confirmed the presence of known densely methylated CpG island sequences. Analysis of random clones, however, showed that the library was dominated by sequences whose G+C content and CpG frequency were intermediate between those of bulk genomic DNA and bona fide CpG islands. When human chromosomes were probed with the library by fluorescent in situ hybridisation (FISH), the predominant sites of labelling were at terminal regions of many chromosomes, approximately corresponding to T-bands. Analysis of the methylation status of random clones indicated that all were heavily methylated at CpGs in blood DNA, but many were under-methylated in sperm DNA. Lack of methylation in germ cells may reduce CpG depletion at some sub-terminal sequences and result in a high density of methyl-CpG when these regions become methylated in somatic cells.

Chromosome Mapping↗

PubMed1999

Nonmethylated transposable elements and methylated genes in a chordate genome.

The genome of the invertebrate chordate Ciona intestinalis was found to be a stable mosaic of methylated and nonmethylated domains. Multiple copies of an apparently active long terminal repeat retrotransposon and a long interspersed element are nonmethylated and a large fraction of abundant short interspersed elements are also methylation free. Genes, by contrast, are predominantly methylated. These data are incompatible with the genome defense model, which proposes that DNA methylation in animals is primarily targeted to endogenous transposable elements. Cytosine methylation in this urochordate may be preferentially directed to genes.

Animals↗

PubMed1999

Estimation of SELEX pool size by measurement of DNA renaturation rates.

We report a general method of measuring the complexity of SELEX pools. In analogy to measurements of genome size by C0t analysis, the complexity of a SELEX pool is measured by determining the reannealing rate of its double-stranded PCR product. We applied this technique to study the selection dynamics of a recently reported SELEX to neutrophil elastase. We found that the number of sequences decreased from 10(7) in round 6 to approximately 60 by round 15, the final round. The intermediate rounds are a mixture of a high abundance/low complexity pool with a low abundance/high complexity pool. As the SELEX progresses, the former pool expands at the expense of the latter. This technique should be useful for studying and optimizing SELEX dynamics, as well as for monitoring the progress of SELEX experiments.

DNA↗

PubMed1999

The Drosophila tissue polarity gene starry night encodes a member of the protocadherin family.

The tissue polarity genes control the polarity of hairs, bristles and ommatidia in the adult epidermis of Drosophila. We report here the identification of a new tissue polarity gene named starry night (stan). Mutations in this essential gene alter the polarity of cuticular structures in all regions of the adult body. The detailed polarity phenotype of stan on the wing suggested that it is most likely a component of the frizzled (fz) pathway. Consistent with this hypothesis, stan appears to be downstream of and required for fz function. We molecularly cloned stan and found that it encodes a huge protocadherin containing nine cadherin motifs, four EGF-like motifs, two laminin G motifs, and seven transmembrane domains. This suggests that Stan functions in signal reception, perhaps together with Fz.

Amino Acid Motifs↗

PubMed1999

Which authorities are alike?

This article describes the first results from the recent revision to The ONS classification of local and health authorities of Great Britain to allow for boundary changes. For each local and health authority of Great Britain as at April 1999 it presents 'most similar' authorities as measured by a selection of 37 socioeconomic and demographic variables from the 1991 Census. These results will assist local and health authorities in identifying other appropriate authorities for comparative studies. A second article, to be published in Population Trends 99, will present the results of the analysis to identify groups of authorities in a hierarchy of new Clusters, Groups and Families for the revised classification.

Censuses↗

PubMed1998

Oesophageal, rectal, axillary, tympanic and pulmonary artery temperatures during cardiac surgery.

PURPOSE: The gradient between temperatures measured at different body sites is not constant; one factor which will change this gradient is rapid changes in body temperature. Measurement of this gradient was done in patients undergoing rapid changes in body temperature to establish the best site to measure temperature and to compare two brands of commercial tympanic thermometers. METHOD: A total of 228 sets of temperatures were measured from probes in the oesophagus, rectum, and axilla and from two brands of tympanic thermometer and compared with pulmonary artery (PA) temperature in 18 adults during cardiac surgery. RESULTS: Measurements from the oesophageal site was closest to PA readings (mean difference 0.0 +/- 0.5 degree C) compared with IVAC tympanic thermometer (mean difference -0.3 +/- 0.5 degree C), Genius tympanic thermometer (mean difference -0.4 +/- 0.5 degree C), axillary (mean difference 0.2 +/- 1.0 degrees C) and rectal (mean difference -0.4 +/- 1.0 degree C) readings. When data during cooling were analysed separately, all sites had similar gradients from PA except for rectal, which was larger. On rewarming, oesophageal readings were closest to PA readings; tympanic readings were closer to PA than were rectal or axillary readings. Readings from the two brands of tympanic thermometer were equivalent. CONCLUSION: Oesophageal temperature is more accurate and will reflect rapid changes in body temperature better than tympanic, axillary, or rectal temperature. When oesophageal temperature cannot be measured, tympanic temperature done by a trained operator should become the reading of choice.

Adult↗

PubMed1998

Van Gogh: a new Drosophila tissue polarity gene.

Mutations in the Van Gogh gene result in the altered polarity of adult Drosophila cuticular structures. On the wing, Van Gogh mutations cause an altered polarity pattern that is typical of mutations that inactivate the frizzled signaling/signal transduction pathway. The phenotype however, differs from those seen previously, as the number of wing cells forming more than one hair is intermediate between that seen previously for typical frizzled-like or inturned-like mutations. Consistent with Van Gogh being involved in the function of the frizzled signaling/signal transduction pathway, Van Gogh mutations show strong interactions with mutations in frizzled and prickle. Mitotic clones of Van Gogh display domineering cell nonautonomy. In contrast to frizzled clones, Van Gogh clones alter the polarity of cells proximal (and in part anterior and posterior) but not distal to the clone. In further contrast to frizzled clones, Van Gogh clones cause neighboring wild-type hairs to point away from rather than toward the clone. This anti-frizzled type of domineering nonautonomy and the strong genetic interactions seen between frizzled and Van Gogh suggested the possibility that Van Gogh was required for the noncell autonomous function of frizzled. As a test of this possibility we induced frizzled clones in a Van Gogh mutant background and Van Gogh clones in a frizzled mutant background. In both cases the domineering nonautonomy was suppressed consistent with Van Gogh being essential for frizzled signaling.

Animals↗

PubMed1998

Patients consulting with Crohn's disease in primary care in England and Wales.

OBJECTIVE: To determine annual incidence and prevalence for patients consulting their GP because of Crohn's disease in England and Wales and compare demographic details with matched controls. DESIGN: We used the fourth Morbidity Statistics in General Practice study (MSGP-4) which covered 468 042 person-years during a 12-month period in 1991-92. METHODS: All GPs reporting a patient with Crohn's disease in MSGP-4 were sent a questionnaire to confirm the diagnosis and obtain supportive details (surgical, pathological, radiological and/or endoscopic). Data concerning ethnicity, social class, smoking status, living in an urban or rural environment and employment had been collected previously. Conditional logistic regression models were used to analyse the data for cases and matched controls. RESULTS: Three hundred and fifteen patients were reported to have Crohn's disease. Replies were obtained to 251 (80%) questionnaires. The diagnosis of Crohn's disease was confirmed in 184 cases (89%) and refuted in 23 cases (11%) -- details were unavailable for 44 patients. The mean age of patients was 44 years, the female:male ratio was 1.46:1, and 108 (59%) patients had required surgery. Thirty-three of 178 (18.5%) patients were diagnosed within the study period. Hence, this study detected a prevalence for consulting Crohn's disease of 54.6-59.8/100,000 and an annual incidence of 10.1-11.1/100,000 in 1991-92. No significant differences were found between cases (n = 291) and controls (n = 1682) with regard to ethnicity, social class, smoking or living in an urban/rural environment. Patients with Crohn's disease had similar employment levels as controls, but were significantly more likely to be registered as permanently sick, odds ratio 4.01 (CI 2.21-7.29). CONCLUSIONS: This national survey, including 1% of the population, suggests there are approximately 30,600 patients consulting their GP because of Crohn's disease in England and Wales, with 5700 new cases diagnosed per year.

Adolescent↗

PubMed1998

Mutations in the cadherin superfamily member gene dachsous cause a tissue polarity phenotype by altering frizzled signaling.

The adult cuticular wing of Drosophila is covered by an array of distally pointing hairs that reveals the planar polarity of the wing. We report here that mutations in dachsous disrupt this regular pattern, and do so by affecting frizzled signaling. dachsous encodes a large membrane protein that contains many cadherin domains and dachsous mutations cause deformed body parts. We found that mutations in dachsous also result in a tissue polarity phenotype that at the cellular level is similar to frizzled, dishevelled and prickle, as many cells form a single hair of abnormal polarity. Although their cellular phenotype is similar to frizzled, dishevelled and prickle, dachsous mutant wings display a unique and distinctive abnormal hair polarity pattern including regions of reversed polarity. The development of this pattern requires the function of frizzled pathway genes suggesting that in a dachsous mutant the frizzled pathway is functioning - but in an abnormal way. Genetic experiments indicated that dachsous was not required for the intracellular transduction of the frizzled signal. However, we found that dachsous clones disrupted the polarity of neighboring wild-type cells suggesting the possibility that dachsous affected the intercellular signaling function of frizzled. Consistent with this hypothesis we found that frizzled clones in a dachsous mutant background displayed enhanced domineering non-autonomy, and that the anatomical direction of this domineering non-autonomy was altered in regions of dachsous wings that have abnormal hair polarity. The direction of this domineering nonautonomy was coincident with the direction of the abnormal hair polarity. We conclude that dachsous causes a tissue polarity phenotype because it alters the direction of frizzled signaling.

Animals↗

PubMed1998

Potential for suicide prevention in primary care? An analysis of factors associated with suicide.

BACKGROUND: General practitioners (GPs) need to be aware of the risk factors for suicide. GP records may provide clues to identifying the relative importance of such risk factors. AIMS: To identify, in suicide cases and matched controls, the patterns of consultation, diagnosis, and treatment of mental illness, and recording of risk factors for suicide. To examine the usefulness of data routinely collected by GPs in computerized databases to investigate treatment of patients in general practice prior to suicide. METHOD: Case control study using GP records from the General Practice Research Database (GPRD). Three controls selected for each case, matched for age, sex, and duration of registration with practice. Information extracted of the prevalence of major disease; diagnosis of, and treatment, or referral for, mental illness; frequency of recording of recent life events; and consultations with the GP in the 12 months prior to death. RESULT: Of the 339 suicide cases recorded, 80% were male, which is similar to the national percentage for this age group. Females were more likely than males to have a history of mental illness and to have been diagnosed and treated for mental illness in the 12 months before death (59% versus 35%), and women were more likely to have previously attempted suicide (47% versus 27%). There was no significant difference between males and females in period of time since last contact with GP practice, but females consulted more frequently. Twenty-nine per cent of cases had not consulted their GP in the six months prior to death. In multivariate analysis, the following were identified as independent risk factors: history of attempted suicide; untreated serious mental illness (odds ratio > 20); recent (past 12 months) marital life event; alcohol abuse; frequent consultations with GP; and previous mental illness. Recording of life events by GPs was poor. CONCLUSIONS: Females at risk of suicide are more likely than males to have been diagnosed and treated for mental illness. It is likely that GPs are under-diagnosed and under-treating males at risk. Data from the GPRD give comparable results to those from other studies. The GPRD is a potentially useful tool for research into relatively uncommon events in general practice.

Adolescent↗

PubMed1997

Protective effects of an aptamer inhibitor of neutrophil elastase in lung inflammatory injury.

Neutrophils play an important part in the development of acute inflammatory injury. Human neutrophils contain high levels of the serine protease elastase, which is stored in azurophilic granules and is secreted in response to inflammatory stimuli. Elastase is capable of degrading many components of extracellular matrix [1-4] and has cytotoxic effects on endothelial cells [5-7] and airway epithelial cells. Three types of endogenous protease inhibitors control the activity of neutrophil elastase, including alpha-1 protease inhibitor (alpha-1PI), alpha-2 macroglobulin and secreted leukoproteinase inhibitor (SLPI) [8-10]. A disturbed balance between neutrophil elastase and these inhibitors has been found in various acute clinical conditions (such as adult respiratory syndrome and ischemia-reperfusion injury) and in chronic diseases. We investigated the effect of NX21909, a selected oligonucleotide (aptamer) inhibitor of elastase, in an animal model of acute lung inflammatory disease [11-14]. This inhibitor was previously selected from a hybrid library of randomized DNA and a small-molecule irreversible inhibitor of elastase (a valine diphenyl ester phosphonate, Fig. 1), by the blended SELEX process [15]. We show that NX21909 inhibits lung injury and neutrophil influx in a dose-dependent manner, the first demonstration of efficacy by an aptamer in an animal disease model.

Animals↗

PubMed1997

Highly potent irreversible inhibitors of neutrophil elastase generated by selection from a randomized DNA-valine phosphonate library.

We incorporated a phosphonate irreversible inhibitor of neutrophil elastase into a randomized DNA library and, using the SELEX process, iteratively selected these assemblies for the most potent elastase inhibitors. The inhibitors were selected against purified elastase and against secreted elastase in the presence of activated neutrophils. Very active aptamer inhibitors were obtained by both methods, with second-order rate constants for inactivation of human neutrophil elastase ranging (1-3) x 10(8) M(-1) min(-1). These rates exceed those of any reported irreversible inhibitor of elastase and exceed the previous best phosphonate inhibitors by 80-fold. The selected inhibitors are also significantly more potent than alpha-1 proteinase inhibitor in blocking degradation of elastin by activated neutrophils. In contrast to a previous experiment [Smith et al. (1995) Chem. Biol. 2, 741-750], a single-enantiomer form of the valyl phosphonate was used rather than a racemic mixture. Our analysis shows that this use of a chirally resolved valyl phosphonate results in selection of much more potent inhibitors and that these inhibitors specifically potentiate a single enantiomeric form of the phosphonate.

Cathepsin G↗

PubMed1997

Differences in traffic judgements between young and old adult pedestrians.

Older pedestrians have been shown to be over-involved in casualty crashes, compared to younger pedestrians, in recent reports. This study set out to investigate whether older pedestrians' road crossing behaviour might render them more vulnerable to crashes because of declines in their physical, sensory, perceptual or cognitive abilities. An initial 'blackspot' accident analysis highlighted the types of crashes in which older (and younger) adult pedestrians were involved and likely crossing actions. Road crossing behaviour was then systematically measured from unobtrusive video recordings of individual road crossings for a sample of younger and older pedestrians at several urban locations. On two-way undivided roads, older pedestrians crossed more frequently when there was closer moving traffic and generally adopted less safe road crossing strategies than their younger counterparts. On one-way divided roads, their crossing behaviour was considerably more safe and similar to that of younger pedestrians. The findings suggest that age-related perceptual and cognitive deficits may play a substantial role in many of the crashes involving older pedestrians.

Accidents, Traffic↗

PubMed1997

In vivo imaging of inflammation using an aptamer inhibitor of human neutrophil elastase.

BACKGROUND: We previously reported the isolation of aptamer irreversible inhibitors of human neutrophil elastase. We now report on the application of aptamer technology to the field of diagnostic imaging. RESULTS: The enzyme elastase has been reported to bind to the surface of activated neutrophils. Using a fluorescent flow cytometry assay, we showed that an aptamer inhibitor of elastase also binds preferentially to activated neutrophils. We then tested the ability of the aptamer to image inflammation in vivo in a rat reverse passive Arthus reaction model. The aptamer achieved a peak target-to-background (T/B) ratio of 4.3 +/- 0.6 in 2 hours. IgG, which is used clinically to image inflammation, took a longer time to achieve a lower T/B: 3.1 +/- 0.1 at 3 hours. The difference in T/B values is due to the faster clearance of the aptamer signal from the blood pool. CONCLUSIONS: It is feasible to apply aptamer ligands for use in diagnostic imaging, where they may offer significant advantages over monoclonal antibodies and other reagents.

Animals↗