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Biomedical subjects

A Curtis

Publications and source records attributed to A Curtis.

At least 55 records · Page 3Linked to original sources
PubMed1997

Comparative genomic hybridization study of primary neuroblastoma tumors. United Kingdom Children's Cancer Study Group.

Neuroblastoma tumors show a complex interaction of genetic abnormalities, among which some are of significant prognostic importance; however, analysis of chromosome changes in this tumor is often unsuccessful. Twenty primary tumors were studied by comparative genomic hybridization (CGH), and abnormalities were found in 19. While these changes included deletions of chromosome arm Ip (45%) and MYCN oncogene amplification (30%), gains of chromosome 17 material were much more frequent (75%). We also found evidence in two cases of a new amplification site at band 2p23.

Adolescent↗
PubMed1996

Synergistic and hierarchical adhesive and topographic guidance of BHK cells.

Guided cell movement is a fundamental process in development and regeneration. We have used microengineered culture substrates to study the interaction between model topographic and adhesive guidance cues in steering BHK cell orientation. Grooves 0.1, 0.5, 1.0, 3.0, and 6.0 microm deep together with pitch-matched aminosilane tracks 5, 12, 25, 50, and 100 microm wide were fabricated on fused silica substrates using photolithographic and dry-etching techniques. The cues were presented to the cells individually, simultaneously in parallel and orthogonally opposed. Cells aligned most strongly to 25-microm-wide adhesive tracks and to 5-microm-wide, 6-microm-deep grooves. Stress fibers and vinculin were found to align with the adhesive tracks and to the grooves and ridges. Cell alignment was profoundly enhanced on all surfaces that presented both cues in parallel. Cells were able to switch alignment from ridges to grooves, and vice versa, depending on the location of superimposed adhesive tracks. Cells aligned preferentially to adhesive tracks superimposed orthogonally over grooves of matched pitch, traversing numerous grooves and ridges. The strength of the cues was more closely matched on narrower 3- and 6-microm-deep gratings with cells showing evidence of alignment to both cues. Confocal fluorescence microscopy revealed two groups of mutually opposed f-actin stress fibers within the same cell, one oriented with the topographic cues and the other with the adhesive cues. However, the adhesive response was consistently dominant. We conclude that cells are able to detect and respond to multiple guidance cues simultaneously. The adhesive and topographic guidance cues modeled here were capable of interacting both synergistically and hierarchically to guide cell orientation.

Animals↗
PubMed1996

Guidance and activation of murine macrophages by nanometric scale topography.

We studied the guidance and activation of macrophages from the P388D1 cell line and rat peritoneum by topographic features on a nanometric scale. Cells were plated on plain fused silica substrata or substrata with microfabricated grooves and steps, 30-282 nm deep. The contact of cells with the patterned surface activated cell spreading and adhesion and increased the number of protrusions of the cell membrane. These changes were accompanied by an increase in the amount of F-actin in cells. The accumulation of F-actin and vinculin in cells was observed along the edges of single steps or grooves. Formation of focal contacts along discontinuities in the substratum was accompanied by the phosphorylation of tyrosine colocalized with F-actin and vinculin. A similar pattern of staining was seen in cells stained for vitronectin receptor, alphaV integrin, but not for integrins alpha5beta1 or alpha3beta1. Cells cultured on nanogrooves showed a higher phagocytotic activity than cells cultured on plain substrata. We show that macrophages can react to ultrafine features of topography of a size comparable to that of a single collagen fiber and become activated by the contact with topographic features.

Animals↗
PubMed1996

Mutation detection in exons 1-14 of the adenomatous polyposis coli gene: identification of an alternatively spliced transcript.

Mutations in the APC gene are responsible for the dominantly inherited colon cancer syndrome, familial adenomatous polyposis (FAP). We have designed PCR primers which allow amplification by RT-PCR of exons 1-14 of the APC gene in six overlapping segments. The amplicons have been screened for the presence of mutations in patients affected with FAP using heteroduplex analysis. One patient has been identified with an alternatively spliced transcript involving exon 14 and a single base insertion mutation within the same exon.

Alternative Splicing↗
PubMed1996

Co-dominant inheritance of hyperekplexia and spastic paraparesis.

In four generations of a family with autosomal dominant hyperekplexia (startle disease), untreated affected adult members had pes cavus and extensor plantar responses, as well as hyper-reflexia. Electroencephalography during a startle, electromyography, nerve conduction velocities and somatosensory evoked potentials were normal. Genetic studies showed linkage to the CSF1R locus on chromosome 5q33-q35, which includes the glycine receptor. This either represents a variant of hyperekplexia with spasticity or suggests that genes for hyperekplexia and a form of hereditary spastic paraparesis may be closely linked.

Adult↗
PubMed1996

Analysis of GLRA1 in hereditary and sporadic hyperekplexia: a novel mutation in a family cosegregating for hyperekplexia and spastic paraparesis.

Hyperekplexia is a rare condition characterised by the presence of neonatal hypertonia and an exaggerated startle response. Mutations have been described in GLRA1, the gene encoding the alpha 1 subunit of the glycine receptor, in dominant families with hyperekplexia and in a single sporadic case, thought to represent an autosomal recessive form of the disease. In this study the coding region of the GLRA1 was analysed in eight probands with hyperekplexia by restriction digest and sequencing. Two familial cases were found to possess the previously described G1192A (R271Q) mutation in exon 6. In an additional family in which hyperekplexia cosegregates with spastic paraparesis, a novel A to G transversion at nucleotide 1206 in exon 6 was detected that changes a lysine at amino acid 276 to a glutamate (K276E). In four sporadic cases no mutations were found. In addition, one familial case did not have a mutation in the coding region of the gene.

Base Sequence↗
PubMed1996

Phenotypic characterization of individuals with 30-40 CAG repeats in the Huntington disease (HD) gene reveals HD cases with 36 repeats and apparently normal elderly individuals with 36-39 repeats.

Abnormal CAG expansions in the IT-15 gene are associated with Huntington disease (HD). In the diagnostic setting it is necessary to define the limits of the CAG size ranges on normal and HD-associated chromosomes. Most large analyses that defined the limits of the normal and pathological size ranges employed PCR assays, which included the CAG repeats and a CCG repeat tract that was thought to be invariant. Many of these experiments found an overlap between the normal and disease size ranges. Subsequent findings that the CCG repeats vary by 8 trinucleotide lengths suggested that the limits of the normal and disease size ranges should be reevaluated with assays that exclude the CCG polymorphism. Since patients with between 30 and 40 repeats are rare, a consortium was assembled to collect such individuals. All 178 samples were reanalyzed in Cambridge by using assays specific for the CAG repeats. We have optimized methods for reliable sizing of CAG repeats and show cases that demonstrate the dangers of using PCR assays that include both the CAG and CCG polymorphisms. Seven HD patients had 36 repeats, which confirms that this allele is associated with disease. Individuals without apparent symptoms or signs of HD were found at 36 repeats (aged 74, 78, 79, and 87 years), 37 repeats (aged 69 years), 38 repeats (aged 69 and 90 years), and 39 repeats (aged 67, 90, and 95 years). The detailed case histories of an exceptional case from this series will be presented: a 95-year-old man with 39 repeats who did not have classical features of HD. The apparently healthy survival into old age of some individuals with 36-39 repeats suggests that the HD mutation may not always be fully penetrant.

Adult↗
PubMed1995

Activation of macrophage-like cells by multiple grooved substrata. Topographical control of cell behaviour.

We studied the influence of substrata topography on the behaviour of murine P388D1 macrophage cell line. Cells were plated on plain fused silica substrata or substrata with microfabricated grooves of varying depth and width. Cell spread area, elongation, orientation and F-actin content were measured on plain substratum and 6 sets of gratings. The speed and persistence of cell movement were also studied. We found that patterned substrata substantially activated cell spreading and elongation and significantly increased the persistence and speed of cell movement, shallow grooves being more effective than deep ones. The contact of cells with micropatterned substrata significantly increased the F-actin content in cells. The sensitivity of LPS (lipopolisaccharide) stimulated and unstimulated macrophages to topographical cues was also compared.

Actins↗
PubMed1994

Genetic heterogeneity in hereditary haemorrhagic telangiectasia.

A locus causing hereditary haemorrhagic telangiectasia (HHT) has recently been mapped to 9q34 in four families and designated HHT1. In this paper, the results of a linkage study showing genetic heterogeneity in four families in whom HHT is segregating are reported. All the previously reported 9q34 linked families contain at least one affected member with a symptomatic pulmonary arteriovenous malformation. We postulate that clinical heterogeneity may also be a feature of HHT with a significantly higher predisposition to symptomatic PAVMs associated with the HHT1 linked families.

Chromosome Mapping↗
PubMed1994

Differentiation of materno-fetal GVHD from Omenn's syndrome in pre-BMT patients with severe combined immunodeficiency.

Materno-fetal GVHD is commonly a fatal condition occurring in patients with severe combined immunodeficiency (SCID). Definitive diagnosis is often difficult. We describe a patient with clinical features suggestive of materno-fetal GVHD but in whom histology was atypical. Y chromosome-specific PCR amplification analysis of DNA extracted from the skin biopsy was performed to detect chimeric evidence of infiltrating maternal T cells. This revealed strong positivity for the Y chromosome, indicating lack of maternal T cell engraftment and thus confirming a diagnosis of Omenn's syndrome, a variant of SCID in which atypical lymphocyte clones give rise to a similar picture. In contrast, Y chromosome-specific PCR analysis of skin biopsy DNA from a male patient with a rash clinically and histologically typical of materno-fetal GVHD revealed absence of the Y chromosome, indicating infiltration of maternal cells and thus confirming the diagnosis of materno-fetal GVHD. Y chromosome-specific PCR analysis is thus a useful investigation for the differentiation of materno-fetal GVHD from Omenn's syndrome in pre-BMT SCID patients presenting with unexplained rash.

Bone Marrow Transplantation↗
PubMed1993

Breaking the adhesions of a cell with its substratum.

Investigation of the relative slowness with which trypsin detaches epithelial cells from their adhesions with a substratum suggests that the adherent surface of the cells is normally rather inaccessible to the enzyme. Trypsinisation of cells through a porous filter allowing access of the enzyme to the underside of the cells greatly accelerated detachment: a result consistent with this explanation.

Animals↗
PubMed1993

Absence of cystic fibrosis mutations in a large Asian population sample and occurrence of a homozygous S549N mutation in an inbred Pakistani family.

The occurrence of cystic fibrosis is very rare in the Asian population. Carriers of the mutations most commonly found in Caucasians were not detected in a large Asian population sample of almost 900 chromosomes. However, an affected Pakistani child born to consanguineous parents was further investigated and shown to be homozygous for the mutation S549N (G-->A). Molecular and clinical data are presented which may improve our understanding of the phenotypic effects of the S549N mutation in the CFTR gene.

Asia↗
PubMed1993

Integrated study of 100 patients with Xp21 linked muscular dystrophy using clinical, genetic, immunochemical, and histopathological data. Part 1. Trends across the clinical groups.

This multidisciplinary study was undertaken to record the variation in gene and protein expression in a large cohort of patients with well defined clinical phenotypes. The patients, whose ages ranged from 4 years to 66 years, spanned a wide range of disease severity. They represented the first 100 patients who had been examined in Newcastle, had undergone a muscle biopsy, and provided a blood sample for DNA analysis. The study had three aims: to observe any trends in the analyses across the clinical groups, to correlate gene and protein expression in individual patients, and to use the data collected to assess the relative usefulness of different techniques in the diagnosis and prognosis of patients with Duchenne and Becker dystrophy (DMD/BMD). In part 1, we describe the clinical assessment of the patients and the trends that were observed across the cohort. The patients were divided into seven groups. Group 1 had severe DMD (n = 21), group 2 had milder DMD (n = 20), group 3 were intermediate D/BMD patients (n = 9), group 4 had severe BMD (n = 5), and group 5 were more typical BMD patients (n = 31). Some patients were too young to be classified (n = 7) and a group of all the female patients were also classified separately (n = 7). The number of DMD and BMD patients was about equal, in accord with disease prevalence in the north of England, but an unusually high proportion were sporadic cases. Dystrophin labelling (performed with up to three antibodies) on both blots and sections increased gradually across the clinical groups. All histopathological indices, except the proportion of fat in biopsy sections, showed clear trends across the groups.

Adolescent↗
PubMed1993

Integrated study of 100 patients with Xp21 linked muscular dystrophy using clinical, genetic, immunochemical, and histopathological data. Part 2. Correlations within individual patients.

This report is the second part of a trilogy from a multidisciplinary study which was undertaken to record the relationships between clinical severity and dystrophin gene and protein expression. The aim in part 2 was to correlate the effect of gene deletions on protein expression in individual patients with well defined clinical phenotypes. Among the DMD patients, most of the deletions/duplications disrupted the open reading frame, but three patients had in frame deletions. Some of the intermediate D/BMD patients had mutations which were frameshifting while others were in frame. All of the deletions/duplications in the BMD patients maintained the open reading frame and 25/26 deletions in typical BMD group 5 started with exon 45. The deletion of single exon 44 was the most common mutation in patients from groups 1 to 3. Dystrophin was detected in sections and blots from 58% of the DMD patients with a size that was compatible with synthesis from mRNA in which the reading frame had been restored. Certain deletions were particularly associated with the occurrence of limited dystrophin synthesis in DMD patients. For example, 9/11 DMD patients missing single exons had some detectable dystrophin labelling compared with 10/24 who had deletions affecting more than one exon. All patients missing single exon 44 or 45 had some dystrophin. Deletions starting or finishing with exons 3 or 51 (8/9) cases were usually associated with dystrophin synthesis whereas those starting or finishing with exons 46 or 52 (11/11) were not. Formal IQ assessments (verbal, performance, and full scores) were available for 47 patients. Mean IQ score among the DMD patients was 83 and no clear relationship was found between gene mutations and IQ. The mutations in patients with a particularly severe deficit of verbal IQ were spread throughout the gene.

Adolescent↗
PubMed1993

Integrated study of 100 patients with Xp21 linked muscular dystrophy using clinical, genetic, immunochemical, and histopathological data. Part 3. Differential diagnosis and prognosis.

This report is the third part of a trilogy from a multidisciplinary study which was undertaken to investigate gene and protein expression in a large cohort of patients with well defined and diverse clinical phenotypes. The aim of part 3 was to review which of the analytical techniques that we had used would be the most useful for differential diagnosis, and which would provide the most accurate indication of disease severity. Careful clinical appraisal is very important and every DMD patient was correctly diagnosed on this basis. In contrast, half of the sporadic BMD patients and all of the sporadic female patients had received different tentative diagnoses based on clinical assessments alone. Sequential observations of quantitative parameters (such as the time taken to run a fixed distance) were found to be useful clinical indicators for prognosis. Intellectual problems might modify the impression of physical ability in patients presenting at a young age. Histopathological assessment was accurate for DMD but differentiation between BMD and other disorders was more difficult, as was the identification of manifesting carriers. Our data on a small number of women with symptoms of muscle disease indicate that abnormal patterns of dystrophin labelling on sections may be an effective way of differentiating between female patients with a form of limb girdle dystrophy and those carrying a defective Xp21 gene. Dystrophin gene analysis detects deletions/duplications in 50 to 90% of male patients and is the most effective non-invasive technique for diagnosis. Quantitative Western blotting, however, would differentiate between all Xp21 and non-Xp21 male patients. In this study we found a clear relationship between increased dystrophin abundance (determined by densitometric analysis of blots) and clinical condition, with a correlation between dystrophin abundance and the age at loss of independent mobility among boys with DMD and intermediate D/BMD. This indicates that blotting is the most sensitive and accurate technique for diagnosis and prognosis.

Adolescent↗