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Biomedical subjects

A Gould

Publications and source records attributed to A Gould.

At least 37 records · Page 2Linked to original sources
PubMed1998

Immunological detection of conformational neoepitopes associated with the serpin activity of plasminogen activator inhibitor type-2.

The physiological roles of plasminogen activator inhibitor-2 (PAI-2) are not yet well understood. Kinetic studies suggest a role in the regulation of plasminogen activator-driven proteolysis in many cell types. This study describes a monoclonal antibody (2H5), which uniquely recognizes neoepitope determinants on PAI-2 appearing after thermodynamic relaxation of the molecule. Enzyme-linked immunosorbent assays and native polyacrylamide gel electrophoresis immunoblotting confirmed the specificity of 2H5 for urokinase type plasminogen activator.PAI-2 complexes. Examination of the affinity of 2H5 for complexes formed between PAI-2 and a synthetic 14-mer reactive site loop peptide, PAI-2 treated with tissue plasminogen activator, or thrombin suggests that the 2H5 epitope is determined exclusively by sequences found only on PAI-2 following proteolytic cleavage of the Arg380-Thr381 bond and insertion of the reactive site loop into beta-sheet A. Peptides lacking both the P13 (Glu368) and P14 (Thr367) residues did not induce a conformational change or affect the inhibitory activity of PAI-2, indicating that one or both of these residues are critical for PAI-2 function. To our knowledge, this is the first description of a monoclonal antibody that can distinguish conformational changes in PAI-2 related specifically to its potential biological function(s).

Antibodies, Monoclonal↗
PubMed1998

Selectivity, sharing and competitive interactions in the regulation of Hoxb genes.

The clustered organisation of Hox complexes is highly conserved in vertebrates and the reasons for this are believed to be linked with the regulatory mechanisms governing their expression. In analysis of the Hoxb4-Hoxb6 region of the HoxB complex we identified enhancers which lie in the intergenic region between Hoxb4 and Hoxb5, and which are capable of mediating the correct boundaries of neural and mesodermal expression for Hoxb5. We examined their regulatory properties in the context of the local genomic region spanning the two genes by transgenic analysis, in which each promoter was independently marked with a different reporter, to monitor simultaneously the relative transcriptional read-outs from each gene. Our analysis revealed that within this intergenic region: (i) a limb and a neural enhancer selectively activate Hoxb4 as opposed to Hoxb5; (ii) a separate neural enhancer is able to activate both genes, but expression is dependent upon competition between the two promoters for the enhancer and is influenced by the local genomic context; (iii) mesodermal enhancer activities can be shared between the genes. We found similar types of regulatory interactions between Hoxb5 and Hoxb6. Together these results provide evidence for three separate general mechanisms: selectivity, competition and sharing, that control the balance of cis-regulatory interactions necessary for generating the proper spatial and temporal patterns of Hox gene expression. We suggest that these mechanisms are part of a regulatory basis for maintenance of Hox organisation.

Alkaline Phosphatase↗
PubMed1998

Initiation of rhombomeric Hoxb4 expression requires induction by somites and a retinoid pathway.

Anteroposterior (AP) patterning in the vertebrate hindbrain is dependent upon the establishment of segmental domains of Hox expression. We investigated the mechanism that governs the early expression of Hoxb4 and found that transient signaling from the paraxial mesoderm induces expression in the hindbrain. Induction involves a retinoid pathway requiring retinoic acid receptor (RAR) function within the neural plate. Characterization of a prerhombomeric enhancer from Hoxb4 reveals that a retinoic acid (RA) response element is an essential component of the early neural response to somite (s) signaling and can interpret positional information for setting the anterior boundary of expression. These data suggest a mechanism whereby, during normal hindbrain development, Hoxb4 expression is initiated by extrinsic signals and is subsequently maintained by Hox feedback circuits. This mechanism also accounts for the ectopic response of Hoxb4 in rhombomere (r) transpositions and after exposure to retinoids.

Animals↗
PubMed1998

Entry into clinical trials in breast cancer: the importance of specialist teams. Scottish Breast Cancer Focus Group and Scottish Cancer Therapy Network.

The aim of this study was to identify the factors influencing entry of women with invasive breast cancer into clinical trials in Scotland. Women diagnosed during 1987 and 1993 were identified from cancer registry data records and their case notes reviewed. Entry into clinical trials was recorded, along with clinical and demographic data for 4688 patients. In 1987, the proportion of women entering clinical trials was 12.3% and, allowing for shorter follow-up, this appeared unchanged in 1993. Patients seen by surgeons with a high case load and those referred to an oncologist were approximately seven times and three times, respectively, more likely to enter a clinical trial (P < 0.0001). The area of Scotland (Health Board) where the woman was first treated also influenced study entry (P < 0.0001), whereas social deprivation had no effect (P = 0.93). Older women, especially those over 80 years of age, were less likely to enter studies (P = 0.05). Extending the management of patients by specialist multidisciplinary teams should increase recruitment into clinical trials and help to identify better treatments for women with breast cancer.

Adult↗
PubMed1998

Variation in the survival of women with breast cancer in Scotland. The Scottish Breast Cancer Focus Group and The Scottish Cancer Therapy Network.

We have investigated factors influencing the survival of women with early breast cancer in Scotland. In a retrospective study, clinical, treatment and 'service' factors, e.g. surgical case load, deprivation and geographical area (health board of first treatment) were recorded from hospital records. A total of 2148 women with invasive breast cancer diagnosed in 1987 were identified from the Scottish Cancer Registry, of whom 1619 without metastases at diagnosis underwent surgery as part of their primary treatment. In a multivariate analysis, clinical factors (age, clinical stage, pathological tumour size, node status and oestrogen receptor status) all influenced survival. After allowing for these clinical factors, surgical case load and deprivation did not have statistically significant effects on survival. By contrast, health board did affect survival. This was explained in part by the selection of patients for surgery. There appeared, however, to be a residual effect that may be related to differences in the use of adjuvant systemic treatment among the different health boards. We conclude that, in Scotland, geographical variation in both surgical and non-surgical treatment has a greater effect on variability in survival for women with breast cancer than surgical case load and deprivation.

Adult↗
PubMed1998

Trends in incidence of and mortality from invasive cancer of the uterine cervix in Scotland (1975-1994).

OBJECTIVE: I. To identify major trends in the incidence of and mortality from invasive cancer of the cervix uteri in Scotland during the twenty year period 1975-1994; II. to consider the extent to which these trends may have been shaped by the introduction of systematic cervical screening. DESIGN: Analysis of annual age standardised and age specific rates for incidence and mortality, based on data collected by the Scottish Cancer Registry and the General Register Office for Scotland. SETTING: Scotland. SUBJECTS: Women registered with the Scottish Cancer Registry as having developed invasive cancer of the cervix during the period of interest. RESULTS: Annual all ages incidence rates of invasive cervical cancer show little overall change over the period 1975-1989, but exhibit a pronounced decline from 1990 onwards. All-ages mortality rates show clear evidence of decline during the period 1975-1994, the rate for 1994 being some 30% lower than that for 1975. Annual age-specific incidence rates show different patterns by age group, with clear evidence of decreasing trends in the age range 50-64 years but different patterns in younger and older age groups. Most age groups show steep declines in incidence from 1990 onwards. Age specific mortality rates for 1975-1994 exhibit the most pronounced decreasing trends in the age range 50-64 years. The trends identified are broadly similar to those experienced in England and Wales over an approximately comparable period. CONCLUSIONS: The overall (all ages) incidence of invasive cervical cancer in Scotland changed little during the period 1975-1989, but declined sharply from 1990 onwards. The most pronounced decline in incidence across the period 1975-1994 appears to have taken place in the age range 50-64 years. This decline has been accompanied by a commensurate fall in mortality in the same age range. These reductions in incidence and mortality may be attributable in part to increased coverage of cervical screening programmes during the period of interest. Evidence from other studies suggest that, without the increased coverage of cervical screening achieved during this period incidence rates in Scotland might have been seen to increase.

Adult↗
PubMed1997

Positive cross-regulation and enhancer sharing: two mechanisms for specifying overlapping Hox expression patterns.

Vertebrate Hox genes display nested and overlapping patterns of expression. During mouse hindbrain development, Hoxb3 and Hoxb4 share an expression domain caudal to the boundary between rhombomeres 6 and 7. Transgenic analysis reveals that an enhancer (CR3) is shared between both genes and specifies this domain of overlap. Both the position of CR3 within the complex and its sequence are conserved from fish to mammals, suggesting it has a common role in regulating the vertebrate HoxB complex. CR3 mediates transcriptional activation by multiple Hox genes, including Hoxb4, Hoxd4, and Hoxb5 but not Hoxb1. It also functions as a selective HOX response element in Drosophila, where activation depends on Deformed, Sex combs reduced, and Antennapedia but not labial. Taken together, these data show that a Deformed/Hoxb4 autoregulatory loop has been conserved between mouse and Drosophila. In addition, these studies reveal the existence of positive cross-regulation and enhancer sharing as two mechanisms for reinforcing the overlapping expression domains of vertebrate Hox genes. In contrast, Drosophila Hox genes do not appear to share enhancers and where they overlap in expression, negative cross-regulatory interactions are observed. Therefore, despite many well documented aspects of Hox structural and functional conservation, there are mechanistic differences in Hox complex regulation between arthropods and vertebrates.

Animals↗
PubMed1997

Functions of mammalian Polycomb group and trithorax group related genes.

Genes of the Polycomb and trithorax groups (PcG and trxG) are part of a cellular memory system that maintains inactive and active states of homeotic gene expression in Drosophila. Recent genetic evidence indicates that several related loci in mammals are also involved in the regulation of Hox genes. Like their Drosophila counterparts, the vertebrate gene products are components of multiprotein complexes that regulate transcriptional activation, repression and aspects of chromatin structure. Initial indications suggest the existence of a large mammalian PcG and trxG family, with a potential to encode multiple specialised functions in cell fate and cell-cycle control.

Animals↗
PubMed1997

Switching the in vivo specificity of a minimal Hox-responsive element.

The homeodomain proteins encoded by the Hox complex genes do not bind DNA with high specificity. In vitro, Hox specificity can be increased by binding to DNA cooperatively with the homeodomain protein extradenticle or its vertebrate homologs, the pbx proteins (together, the PBC family). Here we show that a two basepair change in a Hox-PBC binding site switches the Hox-dependent expression pattern generated in vivo, from labial to Deformed. The change in vivo correlates with an altered Hox binding specificity in vitro. Further, we identify similar Deformed-PBC binding sites in the Deformed and Hoxb-4 genes and show that they generate Deformed or Hoxb-4 expression patterns in Drosophila and mouse embryos, respectively. These results suggest a model in which Hox-PBC binding sites play an instructive role in Hox specificity by promoting the formation of different Hox-PBC heterodimers in vivo. Thus, the choice of Hox partner, and therefore Hox target genes, depends on subtle differences between Hox-PBC binding sites.

Animals↗
PubMed1997

HOXD4 and regulation of the group 4 paralog genes.

From an evolutionary perspective, it is important to understand the degree of conservation of cis-regulatory mechanisms between paralogous Hox genes. In this study, we have used transgenic analysis of the human HOXD4 locus to identify one neural and two mesodermal 3' enhancers that are capable of mediating the proper anterior limits of expression in the hindbrain and paraxial mesoderm (somites), respectively. In addition to directing expression in the central nervous system (CNS) up to the correct rhombomere 6/7 boundary in the hindbrain, the neural enhancer also mediates a three rhombomere anterior shift from this boundary in response to retinoic acid (RA), mimicking the endogenous Hoxd4 response. We have extended the transgenic analysis to Hoxa4 identifying mesodermal, neural and retinoid responsive components in the 3' flanking region of that gene, which reflect aspects of endogenous Hoxa4 expression. Comparative analysis of the retinoid responses of Hoxd4, Hoxa4 and Hoxb4 reveals that, while they can be rapidly induced by RA, there is a window of competence for this response, which is different to that of more 3' Hox genes. Mesodermal regulation involves multiple regions with overlapping or related activity and is complex, but with respect to neural regulation and response to RA, Hoxb4 and Hoxd4 appear to be more closely related to each other than Hoxa4. These results illustrate that much of the general positioning of 5' and 3' flanking regulatory regions has been conserved between three of the group 4 paralogs during vertebrate evolution, which most likely reflects the original positioning of regulatory regions in the ancestral Hox complex.

Animals↗
PubMed1996

A partial double-blind, placebo-controlled study of electronic dental anaesthesia in children.

This study was carried out to determine the effectiveness of electronic dental anaesthesia (EDA) in restorative dental treatment for children. Thirty children were allocated at random to three groups to receive either EDA, a placebo-EDA or anaesthesia by oral injection. One dentist, having introduced and administered these procedures, completed an occlusal restoration in a maxillary permanent first molar in each child. The results showed that the children changed the EDA controls in accordance with pain assessed by their reports and by their facial signs counted in video records by an observer. Both the children and the observer were 'blind' to the difference between EDA and placebo-EDA. There were no statistical differences in: (1) the number of additional oral injections required in all groups to complete treatment, (2) the depth of cavity prepared, (3) the frequency of disruptive activities, (4) the dentist's management behaviour, (5) the dentist's rating of the children's disruptiveness, (6) pain estimated by the children's reports and by facial signs. Treatment time was shortest in the oral injection group, but had no significant correlation with any measure of pain, disruptive behaviour or depth of cavity. It was concluded that EDA was no less effective than anaesthesia administered by injection but, being no more effective than a placebo-EDA, probably worked by distracting the patients.

Adolescent↗
PubMed1996

Langerhan's cell histiocytosis complicating small bowel Crohn's disease.

Langerhan's cell histiocytosis is a rare infiltrative disorder of unknown aetiology. A variety of tissues may be affected, but clinically evident intestinal involvement is unusual. An adult patient is described with Crohn's disease of the terminal ileum who subsequently developed Langerhan's cell histiocytosis with extensive infiltration of the small bowel.

Aged↗
PubMed1995

Leukemia translocation gene, PLZF, is expressed with a speckled nuclear pattern in early hematopoietic progenitors.

The PLZF gene was discovered by studying a rearrangement of the RAR alpha locus in a patient with acute promyelocytic leukemia and a t(11;17) chromosomal translocation. To understand further the potential role(s) of the PLZF gene product in hematopoiesis, we have examined its expression levels in a variety of murine tissues and in established cell lines that are representative of various stages of myeloid and lymphoid development. We show that murine PLZF(mPLZF) is expressed at the highest levels in undifferentiated, multipotential hematopoietic progenitor cells and that its expression declines as cells become more mature and committed to various hematopoietic lineages. Data obtained with established cell lines are corroborated by results showing the lack of human PLZF protein expression in mature peripheral blood mononuclear cells and high PLZF levels in the nuclei of CD34+ human bone marrow progenitor cells. Interestingly, unlike many transcription factors, PLZF protein in these cells possesses distinct punctate nuclear distribution, suggesting its compartmentalization in the nucleus. Taken together, our data suggest a role for PLZF protein in early hematopoiesis and the requirement of downregulation of its expression for proper differentiation of most hematopoietic lineages.

Amino Acid Sequence↗
PubMed1995

A morbillivirus that caused fatal disease in horses and humans.

A morbillivirus has been isolated and added to an increasing list of emerging viral diseases. This virus caused an outbreak of fatal respiratory disease in horses and humans. Genetic analyses show it to be only distantly related to the classic morbilliviruses rinderpest, measles, and canine distemper. When seen by electron microscopy, viruses had 10- and 18-nanometer surface projections that gave them a "double-fringed" appearance. The virus induced syncytia that developed in the endothelium of blood vessels, particularly the lungs.

Adult↗
PubMed1995

Expression of the zinc-finger gene PLZF at rhombomere boundaries in the vertebrate hindbrain.

To investigate the potential biological role(s) of the PLZF gene, discovered as a fusion with the RARA locus in a patient with acute promyelocytic leukemia harboring a t(11;17) chromosomal translocation, we have isolated its murine homologue (mPLZF) and studied its patterns of developmental expression. The levels of mPLZF mRNAs increased perinatally in the liver, heart, and kidney, but with the exception of the heart, they were either absent or very low in the adult tissues. In situ analysis of mPLZF expression in mouse embryos between 7.0 and 10.5 days of development revealed that mPLZF mRNAs and proteins were coexpressed in spatially restricted and temporally dynamic patterns in the central nervous system. In the hindbrain region, a segmental pattern of expression correlated with the development of the rhombomeres. From 9.0 days of development, starting first in rhombomeres 3 and 5, there was an ordered down-regulation of expression in the center of each rhombomere, so that 1 day later elevated levels of mPLZF mRNAs and proteins were restricted to cells surrounding the rhombomeric boundaries. The chicken homologue of the PLZF gene, which we have also cloned, demonstrated a similar segmental pattern of expression in the hindbrain. To date, PLZF represents the only example of a transcription factor with elevated expression at rhombomeric boundaries. The high degree of evolutionary conservation between the patterns of PLZF expression during mammalian and avian central nervous system development suggests that it has an important functional role in the regionalization of the vertebrate hindbrain, potentially regulating boundary cell interactions.

Amino Acid Sequence↗
PubMed1995

Detecting conserved regulatory elements with the model genome of the Japanese puffer fish, Fugu rubripes.

Comparative vertebrate genome sequencing offers a powerful method for detecting conserved regulatory sequences. We propose that the compact genome of the teleost Fugu rubripes is well suited for this purpose. The evolutionary distance of teleosts from other vertebrates offers the maximum stringency for such evolutionary comparisons. To illustrate the comparative genome approach for F. rubripes, we use sequence comparisons between mouse and Fugu Hoxb-4 noncoding regions to identify conserved sequence blocks. We have used two approaches to test the function of these conserved blocks. In the first, homologous sequences were deleted from a mouse enhancer, resulting in a tissue-specific loss of activity when assayed in transgenic mice. In the second approach, Fugu DNA sequences showing homology to mouse sequences were tested for enhancer activity in transgenic mice. This strategy identified a neural element that mediates a subset of Hoxb-4 expression that is conserved between mammals and teleosts. The comparison of noncoding vertebrate sequences with those of Fugu, coupled to a transgenic bioassay, represents a general approach suitable for many genome projects.

Animals↗