Search PubMed⌕ Search

Biomedical subjects

S Walsh

Publications and source records attributed to S Walsh.

At least 37 records · Page 2Linked to original sources
PubMed2001

Prospective evaluation of the morbidity of axillary clearance for breast cancer.

BACKGROUND: Axillary clearance, despite its morbidity, retains an essential role in the management of patients with breast cancer. The aim of this prospective study was to document the development of arm swelling and limitation of shoulder movement following complete axillary clearance. METHODS: One hundred patients who had axillary clearance to level III, for treatment of breast cancer, were followed prospectively for over 1 year. Arm volumes were measured using an optoelectronic volometer and shoulder movements with a goniometer. RESULTS: Ten patients had significant arm swelling at 1 year. The swelling was mild in eight and moderate in two. No patient developed severe swelling. Reduced arm movements were noted in the first week after operation but had returned to normal at 6 months. CONCLUSION: This study provided accurate documentation of the morbidity associated with axillary clearance, together with a reproducible method of arm volume measurement.

Adult↗
PubMed2001

Identification of a lipopolysaccharide alpha-2,3-sialyltransferase from Haemophilus influenzae.

We have identified a gene for the addition of N-acetylneuraminic acid (Neu5Ac) in an alpha-2,3-linkage to a lactosyl acceptor moiety of the lipopolysaccharide (LPS) of the human pathogen Haemophilus influenzae. The gene is one that was identified previously as a phase-variable gene known as lic3A. Extracts of H. influenzae, as well as recombinant Escherichia coli strains producing Lic3A, demonstrate sialyltransferase activity in assays using synthetic fluorescent acceptors with a terminal galactosyl, lactosyl or N-acetyl-lactosaminyl moiety. In the RM118 strain of H. influenzae, Lic3A activity is modulated by the action of another phase-variable glycosyltransferase, LgtC, which competes for the same lactosyl acceptor moiety. Structural analysis of LPS from a RM118:lgtC mutant and the non-typeable strain 486 using mass spectrometry and nuclear magnetic resonance (NMR) spectroscopy confirmed that the major sialylated species has a sialyl-alpha-(2-3)-lactosyl extension off the distal heptose. This sialylated glycoform was absent in strains containing a lic3A gene disruption. Low amounts of sialylated higher molecular mass glycoforms were present in RM118:lgtC lic3A, indicating the presence of a second sialyltransferase. Lic3A mutants of H. influenzae strains show reduced resistance to the killing effects of normal human serum. Lic3A, encoding an alpha-2,3-sialyltransferase activity, is the first reported phase-variable sialyltransferase gene.

Blood Bactericidal Activity↗
PubMed2001

Screening of patients at high risk of colorectal cancer.

OBJECTIVE: To determine the present state of colonoscopic screening practice for patients at a high risk of developing colorectal cancer. METHODS: We assessed colonoscopic screening practice in nine colorectal surgery or gastroenterology units referring patients to the regional genetics centre in the North-west of England. The validity of the pedigree was confirmed by inspection of Hospital records, use of cancer registries and records of general practitioners across the United Kingdom. The screening activity at the participating centres was investigated by means of a questionnaire, site visit and study of case notes. RESULTS: One hundred and eight high risk families were identified. Outside the genetics unit, family history was not taken in a structured manner and family pedigree was not confirmed. In four units screening was offered directly by the consultant surgeon. Differing protocols for screening were in place in six units, but were frequently not adhered to. Colonoscopy completion rates were known in only four units (range 83-97%). Frequency of screening varied from 2 to 5 years. Recording of information was minimal outside the patients' records and there were no dedicated databases. Facilities for families to be screened together existed in three units and the psychological effect of screening was not determined outside the genetics centre. CONCLUSIONS: Screening practice should be standardized and specific criteria met before regular screening is initiated. A dedicated database should be established to record information from units screening patients at high risk of colorectal cancer.

Journal Article↗
PubMed2001

Redox imbalance in Crohn's disease intestinal smooth muscle cells causes NF-kappaB-mediated spontaneous interleukin-8 secretion.

Interleukin-8 (IL-8), a chemokine secreted by cells at injury sites, has recently been recognized as involved in the pathogenesis of Crohn's disease. However, the pathogenesis of enhanced spontaneous transcription of IL-8 by the bowel in patients with Crohn's disease is undefined. Although IL-8 is secreted primarily by neutrophils, macrophages, and endothelial and epithelial cells, we observed the involvement of mesenchymal cells in the inflammatory process. A smooth muscle cell line isolated from the ileum of a patient with Crohn's disease (CDISM) and maintained in culture exhibited spontaneous transcription and secretion of IL-8 when compared with intestinal smooth muscle cells obtained from a normal subject (NHISM). Furthermore, IL-8 transcription from CDISM cells was associated with remarkable spontaneous activation of the oxidant-sensitive transcription factor NF-kappaB, as assessed by transient transfection assays with an IL-8 promoter reporter construct, Western blot analysis, and electrophoretic mobility shift assays (EMSA). Finally, we report here that CDISM cells exhibit significantly altered redox balance. The antioxidant pyrrolidine dithiocarbamate (PDTC) restored the redox equilibrium by mechanisms that inhibit binding of NF-kappaB to its cognate site on the IL-8 promoter. These findings suggest that restoration of the redox balance could hold promise for therapeutic intervention in Crohn's disease.

Antioxidants↗
PubMed2001

High concentrations of dexamethasone suppress the proliferation but not the differentiation or further maturation of human osteoblast precursors in vitro: relevance to glucocorticoid-induced osteoporosis.

OBJECTIVE: The use of glucocorticoids (GCs) in the treatment of RA is a frequent cause of bone loss. In vitro, however, this same class of steroids has been shown to promote the recruitment and/or maturation of primitive osteogenic precursors present in the colony forming unit-fibroblastic (CFU-F) fraction of human bone and marrow. In an effort to reconcile these conflicting observations, we investigated the effects of the synthetic GC dexamethasone (Dx) on parameters of growth and osteogenic differentiation in cultures of bone marrow stromal cells derived from a large cohort of adult human donors (n=30). METHODS: Marrow suspensions were cultured in the absence and presence of Dx at concentrations between 10 pm and 1 microm. After 28 days we determined the number and diameter of colonies formed, the total number of cells, the surface expression of receptors for selected growth factors and extracellular matrix proteins and, based on the expression of the developmental markers alkaline phosphatase (AP) and the antigen recognized by the STRO-1 monoclonal antibody, the proportion of cells undergoing osteogenic differentiation and their extent of maturation. RESULTS: At a physiologically equivalent concentration, Dx had no effect on the adhesion of CFU-F or on their subsequent proliferation, but did promote their osteogenic differentiation and further maturation. These effects were independent of changes in the expression of the receptors for fibroblast growth factors, insulin-like growth factor 1, nerve growth factor, platelet-derived growth factors and parathyroid hormone/parathyroid hormone-related protein, but were associated with changes in the number of cells expressing the alpha(2) and alpha(4), but not beta(1), integrin subunits. At supraphysiological concentrations, the effects of Dx on the osteogenic recruitment and maturation of CFU-F and their progeny were maintained but at the expense of a decrease in cell number. CONCLUSIONS: A decrease in the proliferation of osteogenic precursors, but not in their differentiation or maturation, is likely to be a key factor in the genesis of GC-induced bone loss.

Adult↗
PubMed2001

Unexplained groin pain: safety and reliability of herniography for the diagnosis of occult hernias.

A retrospective study of our initial experience of herniography in a district general hospital is presented. A total of 43 herniograms were performed in 41 patients (median age 57, range 16-77, 27 males, 14 females) over a two year period. Four herniograms were unsuccessful due to failed intraperitoneal contrast injection, of which two were repeated (success rate 90.5%). A total of 25 groin hernias were identified radiologically (two on the asymptomatic side). Twenty one patients underwent surgery and a hernia was confirmed in 19 (true positive rate 90.5%). Sixteen herniograms were considered negative and after a median follow up of 28 months (range 16-42 months), none of these patients have developed a hernia. There were no major complications. It is concluded that herniography is a safe and reliable method of determining or excluding the presence of an occult groin hernia.

Adolescent↗
PubMed2001

Neutrophil transepithelial migration: regulation at the apical epithelial surface by Fc-mediated events.

Neutrophil (PMN) transepithelial migration is a major effector of epithelial defense in inflammatory diseases involving mucosal surfaces. However, major receptor-ligand interactions between epithelial cells and PMN remain incompletely characterized. To better define the molecular events involved in PMN interactions with epithelial cells, we produced a monoclonal antibody called g82 that inhibited PMN transepithelial migration in the physiological basolateral-to-apical direction. The g82 antigen localized to the apical surface of human colonic epithelium and was significantly upregulated under inflammatory conditions. Immunoprecipitation revealed two polypeptides of M(r) 207 and 32 kDa. F(ab')(2) fragments from g82 IgG had no effect on transmigration, suggesting Fc dependence. Further experiments confirmed dependence on the PMN Fc receptor CD32A and that the observed effects were secondary to a failure of PMN to detach from the apical epithelial surface. These Fc-mediated events were epitope specific since binding, isotype-matched antibodies did not affect detachment. These results identify a new mechanism for retention of PMN at the apical epithelial surface following transepithelial migration. This pathway may be important in pathogen clearance and mucosal pathophysiology associated with autoimmunity.

Animals↗
PubMed2001

Respiratory abdominal muscle recruitment and chest wall motion in myotonic muscular dystrophy.

Abdominal muscles are selectively active in normal subjects during stress and may increase the potential energy for inspiration by reducing the end-expiratory lung volume (EELV). We hypothesized that a similar process would occur in subjects with myotonic muscular dystrophy (MMD), but would be less effective, because of to their weakness and altered chest wall mechanics. Fine-wire electromyography (EMG) of the transversus abdominis (TA), internal oblique (IO), external oblique, and rectus abdominis was recorded in 10 MMD and 10 control subjects. EMG activity, respiratory inductive plethysmography, and gastric pressure were recorded during static pressure measurement and at increasing levels of inspiratory resistance breathing. EELV was reduced and chest wall motion was synchronous only in controls. Although the TA and IO were selectively recruited in both groups, EMG activity of the MMD group was twice that of controls at the same inspiratory pressure. In MMD subjects with mildly reduced forced vital capacity, significant differences can be seen in abdominal muscle recruitment, wall motion, work of breathing, and ventilatory parameters.

Abdomen↗
PubMed2001

Carbon dioxide contributes to the beneficial effect of pressurization in a portable hyperbaric chamber at high altitude.

Regional cerebral oxygenation (rSO2) and peripheral oxygen saturation (SpO2) have been studied in subjects inside a portable hyperbaric chamber at altitude during pressurization. The effects of the accumulation of carbon dioxide within the chamber on rSO2 and SpO2 have also been investigated. Three studies of cerebral regional oxygenation were undertaken, using near-IR spectroscopy, in subjects who had ascended to 3475 m in the Alps, 4680 m in the Andes or 5005 m in the Himalayas. At 3475 m and 5005 m the effects of the removal of inspired carbon dioxide by a soda lime scavenger were also studied. On pressurization of the chamber to 19.95 kPa, inspired carbon dioxide rose within the chamber from 0.03% (0.06 kPa) ambient to over 1% (1.3 kPa). At 5005 m, SpO2 rose from a baseline of 79.5% (S.D. 4.5%) to 95.9% (2.0%) (P<0.0001), and cerebral rSO2 rose from 64.6% (3.4%) to 69.4% (3.6%) (P<0.0001). The introduction of a soda lime CO2 scavenger into the breathing circuit resulted in a drop in SpO2 from 95.9% (2.03%) to 93.6% (2.07%) (P<0.001) and a fall in rSO2 from 69.4% (3.64%) to 68.5% (3.5%) (P<0.01). Chamber pressure was maintained throughout at 19.95 kPa. Similar changes were seen at the other altitudes. Cerebral rSO2 increased rapidly following pressurization at all three altitudes. Scavenging of inspired carbon dioxide was associated with a significant fall in cerebral rSO2 and SpO2, and we estimate that the contribution of carbon dioxide may account for up to one-third of the beneficial effect of the portable hyperbaric chamber.

Adult↗
PubMed2001

Factors associated with low bone mineral density in female patients with systemic lupus erythematosus.

OBJECTIVE: To study risk factors for low bone mineral density (BMD, g/cm) in patients with systemic lupus erythematosus (SLE). METHODS: Ninety-two consecutive patients with SLE followed by rheumatology faculty between 1997 and 1999 completed a questionnaire regarding lifestyle during the clinic visit, a chart review was performed, and data were collected for the time of the first dual energy x-ray absorptiometry (DXA) examination. Univariate and multivariate statistical analyses were used to assess relationships between various risk factors and BMD. RESULTS: Ninety-eight percent of patients had received prednisone, 51% were postmenopausal (9 of whom received hormone replacement therapy), 68% had received hydroxychloroquine, and 15% were osteoporotic. The following factors were found to be significantly related to lower BMD by univariate analysis: Caucasian race, older age at diagnosis, higher age at the time of the first DXA, longer disease duration, higher cumulative corticosteroid dose, higher SLE Damage Index score, and postmenopausal status. In the multivariate analysis only the following factors were significant: Caucasian race, increased number of pregnancies, postmenopausal status, higher SLE Damage Index, and higher cumulative corticosteroid dose. An unexpected finding was that taking hydroxychloroquine was the only factor associated with higher BMD of the hip and spine in the univariate analysis, and it remained predictive of higher BMD of the hip and spine in the multivariate analysis. CONCLUSION: Hydroxychloroquine appears to protect against low BMD in corticosteroid treated patients with SLE.

Absorptiometry, Photon↗
PubMed2000

Sigmoid volvulus after laparoscopic cholecystectomy. An unusual complication.

Laparoscopic cholecystectomy has become the standard surgical technique for treating symptomatic gallbladder disease. Intestinal obstruction after laparoscopic cholecystectomy is unusual. We present the case of a 37-year-old man who underwent routine laparoscopic cholecystectomy for cholelithiasis using an American four-port technique. He was well 24 h postoperatively and was discharged. He presented 36 h later with clinical features of bowel obstruction. A sigmoid loop was seen on a plain abdominal radiograph. Laparotomy revealed distension of the large and small bowel to the level of the rectosigmoid junction and a sigmoid volvulus. This was reduced by releasing adhesions to lengthen the sigmoid mesentery. A primary sigmoid resection and anastomosis was not attempted due to luminal discrepancy and lack of bowel preparation. The patient underwent interval sigmoid colectomy 2 weeks later. A sigmoid volvulus following laparoscopic cholecystectomy has not been previously reported. It may be related to the induction of the pneumoperitoneum, combined with the lateral tilt of the table and a long redundant sigmoid colon. This case expands the range of potential complications associated with laparoscopic cholecystectomy and illustrates the need for continued vigilance after apparently routine procedures.

Adult↗
PubMed2000

Newly recognised craniosynostosis syndrome that does not map to known disease loci.

We describe a consanguineous family of Pakistani origin with five sibs, three of whom were affected by craniosynostosis of variable presentation. In addition, they had other congenital abnormalities principally affecting neurological, ocular, and limb development. We provide linkage evidence using intragenic and flanking microsatellite markers suggesting that the disease in this family was not caused by a mutation in one of the known craniosynostosis loci (FGFR1, FGFR2, FGFR3, MSX2, TWIST). Given the clinical novelty and parental consanguinity, we hypothesise that the affected individuals were autozygous for a recessively inherited mutation, at a novel locus, predisposing to craniosynostosis.

Child↗
PubMed2000

Combinatorial control of cyclin B1 nuclear trafficking through phosphorylation at multiple sites.

Entry into mitosis is regulated by the Cdc2 kinase complexed to B-type cyclins. We and others recently reported that cyclin B1/Cdc2 complexes, which appear to be constitutively cytoplasmic during interphase, actually shuttle continually into and out of the nucleus, with the rate of nuclear export exceeding the import rate (). At the time of entry into mitosis, the import rate is increased, whereas the export rate is decreased, leading to rapid nuclear accumulation of Cdc2/cyclin B1. Although it has recently been reported that phosphorylation of 4 serines within cyclin B1 promotes the rapid nuclear translocation of Cdc2/cyclin B1 at G(2)/M, the role that individual phosphorylation sites play in this process has not been examined (, ). We report here that phosphorylation of a single serine residue (Ser(113) of Xenopus cyclin B1) abrogates nuclear export of cyclin B1. This serine lies directly within the cyclin B1 nuclear export sequence and, when phosphorylated, prevents binding of the nuclear export factor, CRM1. In contrast, analysis of phosphorylation site mutants suggests that coordinate phosphorylation of all 4 serines (94, 96, 101, and 113) is required for the accelerated nuclear import of cyclin B1/Cdc2 characteristic of G(2)/M. Additionally, binding of cyclin B1 to importin-beta, the factor known to be responsible for the slow interphase nuclear entry of cyclin B1, appears to be unaffected by the phosphorylation state of cyclin B. These data suggest that a distinct import factor must be recruited to enhance nuclear entry of Cdc2/cyclin B1 at the G(2)/M transition.

Active Transport, Cell Nucleus↗
PubMed2000

Lack of germline CDK6 mutations in familial melanoma.

Germline mutations in genes encoding several components of the retinoblastoma pathway have been linked with inherited predisposition to melanoma. Most commonly, such mutations involve CDKN2A, a cyclin-dependent kinase inhibitor of two kinases, CDK4 and CDK6, which phosphorylate the retinoblastoma protein (pRB) and thereby promote passage through the G1/S cell-cycle restriction point. Less frequently, germline mutations in the CDK4 gene have also been linked with an increased risk of melanoma. Despite the sequence and functional homology between CDK4 and CDK6, the role of germline mutations in CDK6 in melanoma predisposition is unknown. We detected no CDK6 mutations within the p16 (CDKN2A) binding domain in index cases from 60 melanoma-prone kindreds that lacked germline mutations in the coding regions of either CDKN2A or within the entire CDK4 coding region. We conclude that germline mutations in CDK6 do not make a significant contribution to melanoma predisposition.

Amino Acid Sequence↗
PubMed2000

UK CropNet: a collection of databases and bioinformatics resources for crop plant genomics.

The UK Crop Plant Bioinformatics Network (UK CropNet) was established in 1996 in order to harness the extensive work in genome mapping in crop plants in the UK. Since this date we have published five databases from our central UK CropNet WWW site (http://synteny.nott.ac.uk/) with a further three to follow shortly. Our resource facilitates the identification and manipulation of agronomically important genes by laying a foundation for comparative analysis among crop plants and model species. In addition, we have developed a number of software tools that facilitate the visualisation and analysis of our data. Many of our tools are made freely available for use with both crop plant data and with data from other species.

Crops, Agricultural↗
PubMed2000

Expression of the developmental markers STRO-1 and alkaline phosphatase in cultures of human marrow stromal cells: regulation by fibroblast growth factor (FGF)-2 and relationship to the expression of FGF receptors 1-4.

Autologous marrow stromal cells have been proposed as an adjuvant in the treatment of bone defects and diseases. This will require the development of culture conditions that permit their rapid expansion ex vivo while retaining their potential for further differentiation. Fibroblast growth factor (FGF)-2 has been proposed as a candidate for the ex vivo expansion of cells with enhanced osteogenic potential, and we have explored this possibility further using cells obtained from a large cohort of adult human donors. Treatment with FGF-2 (0.001-2.5 ng/mL) had no detectable effect on colony formation, but markedly increased their proliferative potential and that of their immediate progeny, as shown by the increases in colony size and cell number. Based on the observed increase in the expression of the developmental markers STRO-1 and alkaline phosphatase (AP), a major target for the actions of FGF-2 appears to be the more primitive cells of the osteoblast lineage, and that, when added in combination with the synthetic glucocorticoid dexamethasone (Dx), it interacts positively to promote further cell maturation. The maintenance of adequate levels of ascorbate was shown to be a critical component in determining the nature of the effect of FGF-2 on AP expression. Variation in the response (predominantly in the magnitude and/or sensitivity) of the cultured cell populations to treatment with FGF-2 was apparent, but a preliminary analysis indicated that this was not due to differences in the age or gender of the donors used. The cultured cell populations were found to express multiple FGF receptors (FGFRs; 1-4) and the observed changes in the spectrum and abundance of FGFRs expressed in relation to that of STRO-1 and AP are consistent with their expression being developmentally regulated during the process of osteogenic differentiation. These results provide novel insights into the mechanism of action of FGF-2 on human cells of the osteoblast lineage and support the use of this factor, alone or in combination with Dx, for the rapid, ex vivo expansion of cell populations with enhanced osteogenic potential.

Adult↗
PubMed2000

Functional haploinsufficiency of the human homeobox gene MSX2 causes defects in skull ossification.

The genetic analysis of congenital skull malformations provides insight into normal mechanisms of calvarial osteogenesis. Enlarged parietal foramina (PFM) are oval defects of the parietal bones caused by deficient ossification around the parietal notch, which is normally obliterated during the fifth fetal month. PFM are usually asymptomatic, but may be associated with headache, scalp defects and structural or vascular malformations of the brain. Inheritance is frequently autosomal dominant, but no causative mutations have been identified in non-syndromic cases. We describe here heterozygous mutations of the homeobox gene MSX2 (located on 5q34-q35) in three unrelated families with PFM. One is a deletion of approximately 206 kb including the entire gene and the others are intragenic mutations of the DNA-binding homeodomain (RK159-160del and R172H) that predict disruption of critical intramolecular and DNA contacts. Mouse Msx2 protein with either of the homeodomain mutations exhibited more than 85% reduction in binding to an optimal Msx2 DNA-binding site. Our findings contrast with the only described MSX2 homeodomain mutation (P148H), associated with craniosynostosis, that binds with enhanced affinity to the same target. This demonstrates that MSX2 dosage is critical for human skull development and suggests that PFM and craniosynostosis result, respectively, from loss and gain of activity in an MSX2-mediated pathway of calvarial osteogenic differentiation.

Adult↗