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Biomedical subjects

N M Croft

Publications and source records attributed to N M Croft.

12 recordsLinked to original sources
PubMed2006

Inflammatory bowel disease.

Twenty five per cent of inflammatory bowel disease presents in childhood. Growth and nutrition are key issues in the management with the aim of treatment being to induce and then maintain disease remission with minimal side effects. Only 25% of Crohn's disease presents with the classic triad of abdominal pain, weight loss, and diarrhoea. Most children with ulcerative colitis have blood in the stool at presentation. Inflammatory markers are usually although not invariably raised at presentation (particularly in Crohn's disease). Full investigation includes upper gastrointestinal endoscopy and ileocolonoscopy. Treatment requires multidisciplinary input as part of a clinical network led by a paediatrician with special expertise in the management of the condition.

Adolescent↗
PubMed2001

Blocking Smad7 restores TGF-beta1 signaling in chronic inflammatory bowel disease.

TGF-beta1 functions as a negative regulator of T cell immune responses, signaling to target cells using the Smad family of proteins. We show here that Smad7, an inhibitor of TGF-beta1 signaling, is overexpressed in inflammatory bowel disease (IBD) mucosa and purified mucosal T cells. Both whole tissue and isolated cells exhibit defective signaling through this pathway, as measured by phospho-Smad3 immunoreactivity. Specific antisense oligonucleotides for Smad7 reduce Smad7 protein expression in cells isolated from patients with IBD, permitting the cells to respond to exogenous TGF-beta1. TGF-beta1 cannot inhibit proinflammatory cytokine production in isolated lamina propria mononuclear cells from patients with Crohn disease (CD), but inhibition of Smad7 restores TGF-beta1 signaling and enables TGF-beta1 to inhibit cytokine production. In inflamed mucosal tissue explants from patients with CD, inhibition of Smad7 also restores p-Smad3 and decreases proinflammatory cytokine production, an effect that is partially blocked by anti-TGF-beta1. These results show that Smad7 blockade of TGF-beta1 signaling helps maintain the chronic production of proinflammatory cytokines that drives the inflammatory process in IBD and that inhibition of Smad7 enables endogenous TGF-beta to downregulate this response.

Activin Receptors, Type I↗
PubMed2000

High intraluminal fluid flow increases intestinal IgA output.

BACKGROUND: Stool IgA output in normal stool or chronic diarrhoea is a fraction of that recorded in high-output watery diarrhoea due to cholera. We hypothesized that high intestinal fluid flow leads to increased IgA output, and this is not a consequence of reduced degradation/reabsorption. METHODS: Daily intestinal outputs of IgA and other secretory and non-secretory proteins were measured in stool from 14 volunteers with ileostomies and compared with the output during whole-gut lavage, a whole-gut perfusion system. RESULTS: Output into whole-gut lavage was significantly higher for all the proteins (P=0.02 to 0.001). Median IgA output into ileostomy effluent (IE) was 3.6 mg/kg/day compared with 26 mg/kg/day into whole-gut lavage fluid (WGLF). Thus IgA recovery in stool was only 12.7% of the amount in corresponding WGLF. Similar results were found for other proteins: specific IgA and IgM antibodies (5.4%-20.3%), IgM (42.4%), IgG (8.9%), and albumin (9.3%). Six subjects with IE water content >92% had increased recovery of IgA compared with eight with <92% water. In vitro, experiments predict that degradation of IgA within the small bowel results in 80% remaining compared with the 12.7% measured in vivo. CONCLUSIONS: Our data show that high intraluminal fluid flow increases the intestinal output of IgA and other proteins, and this is not a consequence of reduced degradation/reabsorption in the colon or small bowel. This increased protein output may be a non-specific response in the early stages of acute diarrhoea.

Adolescent↗
PubMed2000

Intestinal inflammation in cystic fibrosis.

BACKGROUND: There is controversy about whether the inflammatory response observed in the cystic fibrosis (CF) lung occurs secondary to bacterial infection or is caused by a dysregulation of the inflammatory response associated with the basic cellular defect of CF. AIMS: To study the inflammatory response in the gastrointestinal tract of children with CF; and to investigate whether there is increased inflammation in the gastrointestinal tract of CF children with fibrosing colonopathy. METHODS: Whole gut lavage was performed on 21 pancreatic insufficient children with CF, who were clinically well, five children with CF and fibrosing colonopathy, and 12 controls. Intestinal outputs of plasma derived proteins (albumin, alpha(1) antitrypsin, IgG), secretory immunoglobulins (IgA and IgM), cellular constituents (eosinophil cationic protein and neutrophil elastase), and cytokines (interleukin 8 and interleukin 1beta) were measured. RESULTS: Compared to controls, the 21 CF patients, with no intestinal complications, had increased intestinal outputs of albumin, IgG, IgM, eosinophil cationic protein, neutrophil elastase, interleukin 1beta, and interleukin 8. Similar values were obtained for the CF patients with fibrosing colonopathy. CONCLUSIONS: These data suggest that there is immune activation in the gastrointestinal mucosa of children with cystic fibrosis, which may result from the basic cellular defect. Fibrosing colonopathy does not appear to be associated with increased inflammation.

Adolescent↗
PubMed1996

Direct assessment of gastrointestinal inflammation and mucosal immunity in children with cystic fibrosis.

Fibrosing colonopathy is a recently described complication of cystic fibrosis, of unknown aetiology but possibly related to treatment with high-dose pancreatic enzyme supplements. We have used a whole gut perfusion technique to study subclinical gut inflammation in cystic fibrosis patients; concentrations of haemoglobin, IgG, albumin, alpha-1-antitrypsin, granulocyte elastase, IL1 beta, and IL8 were measured in whole gut lavage fluid: 23 tests were performed in 17 children with cystic fibrosis (20 elective tests, three lavages to treat distal intestinal obstruction syndrome (DIOS)). None has had fibrosing or haemorrhagic colitis. There were 12 tests in control children with constipation or precolonoscopy. Moderately abnormal results were obtained for many of the parameters studied, in specimens from all the cystic fibrosis children; however there were no significant differences between tests on high-dose and low-dose enzyme supplements of the same brand in the five children who had duplicate tests performed electively. The lavage fluid specimens from two cystic fibrosis children were strikingly abnormal in all tests apart from haemoglobin and alpha-1-antitrypsin. These were two of the three children with DIOS, and were also the only cases in the series taking Nutrizym 22. These data suggest that the majority of cystic fibrosis children, including those on high-dose enzyme supplements, do not have clinically significant colitis, but that there is subclinical mucosal inflammation in a minority (two of 17 in this series), for which DIOS and/or Nutrizym 22 treatment may be risk factors. Alternatively, inflammation and dysmotility in the proximal colon may be directly produced by a drug or other agent, producing a clinical syndrome indistinguishable from DIOS. Tests for indices of inflammation in gut lavage fluid offer a new approach to the detection and measurement of iatrogenic intestinal and colonic injury.

Adolescent↗
PubMed1995

Gut inflammation in children with cystic fibrosis on high-dose enzyme supplements.

We used a whole-gut perfusion technique to study subclinical gut inflammation in children with cystic fibrosis (18 elective tests, three lavages to treat distal intestinal obstruction syndrome); and in 12 control children with constipation or pre-colonoscopy. We assayed for haemoglobin, IgG, albumin, alpha-1-antitrypsin, granulocyte elastase, interleukin-1 beta (IL-1 beta) and IL-8 concentrations in whole-gut lavage fluid. Results for two children with distal intestinal obstruction syndrome, the only children in the series taking Nutrizym 22, were strikingly abnormal. This new test has revealed subclinical gut mucosal inflammation in a minority of CF children, for which distal intestinal obstruction syndrome, Nutrizym 22 treatment, or both, may be risk factors.

Adolescent↗
PubMed1995

Technical report: results of immunological tests on faecal extracts are likely to be extremely misleading.

Clinical investigation of gut immunity is difficult because of the need to study intestinal tissues or secretions directly. Others have reported that immunoglobulins, antibodies and cytokines can be detected in saline extracts of faeces. We have assessed the validity of this approach by measuring immunoglobulins, albumin, alpha 1-antitrypsin and isotype-specific antibodies in matched samples of faeces and whole gut lavage fluid. Results were compared as estimated output per day, and by using haemoglobin as a common reference substance. Samples were obtained from 10 patients with active inflammatory bowel disease and 10 with other benign GI diseases. For immunoglobulins, albumin and antibodies, the amount detected in faeces varied from < 0.01% to 35.5% (based on estimated daily output) and < 0.01% to 18.5% (based on haemoglobin) of the amount known to be produced in the gut from results of assays on whole gut lavage fluid (WGLF); there were significantly higher rates of recovery in faecal specimens from patients with active gut inflammation than from other patients. Detection rates and titres of specific antibody in faeces were even lower than those for immunoreactive IgA. These data indicate that immunological tests on saline extracts of faeces do not represent the true status of the gut humoral immune system, and such studies should be strongly discouraged.

Adult↗
PubMed1993

Ewing's sarcoma in a child with human immunodeficiency virus (type 1) infection.

A male child with vertically transmitted human immunodeficiency virus type 1 (HIV) infection developed a Ewing's sarcoma of the left fibula at 6.1 years of age. We report the antitumour chemotherapy given and the response of the tumour. Six months after tumour diagnosis the child died of probable HIV encephalopathy. This is the first reported case of Ewing's sarcoma in an HIV-infected child.

AIDS Dementia Complex↗
PubMed1993

Cardiac dysfunction in paediatric HIV infection.

A child under long term surveillance for vertically acquired HIV-I infection developed respiratory symptoms. Dilated cardiomyopathy was diagnosed. Clinical and echocardiographic assessment of six other children with symptomatic HIV disease showed no evidence of cardiac dysfunction. The exact prevalence of this complication in paediatric HIV infection is unknown, but the potential diagnostic difficulties are highlighted.

Cardiomyopathy, Dilated↗