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Biomedical subjects

M N Marsh

Publications and source records attributed to M N Marsh.

At least 37 records · Page 2Linked to original sources
PubMed1993

Hepatobiliary complications of total parenteral nutrition.

The relationships between various hepatobiliary disorders and the administration of total parenteral nutrition (TPN) were reviewed and, in particular, the role of TPN in their pathogenesis was critically evaluated. Several clinical and pathological entities including steatosis, steatohepatitis, cholestasis, and cholelithiasis have been commonly linked to TPN, and instances of chronic decompensated liver disease have been reported. However, it is concluded that it is often difficult to extricate the effects of TPN on hepatobiliary function from many other hepatotoxic factors that may be operative in these patients. Thus, whereas considerable evidence exists to support a role fro carbohydrate or calorie excess in TPN solutions in the pathogenesis of steatosis, a loss of enteric stimulation and not TPN per se may be the primary factor in the development of cholestasis, biliary sludge, and gallstones. The apparent predilection of infants to TPN-related cholestasis may be based on the relative immaturity of the neonatal biliary excretory system.

Adult↗
PubMed1993

Time-course of adhesion molecule expression in rectal mucosa of gluten-sensitive subjects after gluten challenge.

Adhesive interactions between endothelium and circulating cells, such as monocytes, neutrophils and lymphocytes, are crucial for localizing the inflammatory response. We investigated the inflammatory response of rectal mucosa to local gluten challenge as a dynamic model of antigen-induced tissue injury, during which the expression of adhesion molecules on leucocytes and endothelial cells could be sequentially observed. Expression of ELAM-1, ICAM-1 and VCAM-1 was monitored in 10 treated and eight untreated patients with gluten sensitivity (coeliac disease), and in five disease controls for up to 4 h (short challenge), while a further seven treated coeliacs were monitored for up to 24 h (long challenge) following rectal gluten challenge. In the former, the expression of VCAM-1 and ELAM-1 was significantly raised 4 h after gluten challenge compared with controls. VCAM-1 and ELAM-1 expression was also increased in mucosae of treated patients, but to a lesser extent. VCAM-1 expression continued to increase for up to 24 h after gluten, while ELAM-1 had begun to wane by 4 h, reaching basal levels by 24 h. In contrast, the expression of ICAM-1 did not change in any of the disease groups studied. These findings relate to significant increases in lymphocytes (CD3+ cells) after 8 h, and neutrophils (CD15+ cells) after 4 h in the lamina propria. This approach has permitted novel studies of the inflammatory response to a defined antigen in sensitized (gluten-sensitive) human patients.

Celiac Disease↗
PubMed1993

Morphometric analysis of intestinal mucosa. V. Quantitative histological and immunocytochemical studies of rectal mucosae in gluten sensitivity.

To study changes in rectal mucosa that might be attributable to the effects of gluten, rectal biopsy specimens from untreated and treated gluten sensitised subjects were analysed morphometrically and by immunohistochemical techniques and were compared with a series of disease control mucosae. Although morphometry showed increased populations of plasma cells, lymphocytes, and mast cells in the mucosae of untreated patients, which were reduced (except for mast cells) by dietary gluten restriction, immunohistochemical techniques were far more sensitive in defining these changes. There were highly significant increases in CD3+ and gamma delta+ lymphocytes within both the lamina propria and the epithelium while neutrophils (CD15+ cells) were not at all prominent. Activated (CD25+) lymphocytes expressing interleukin (IL)-2 receptors were increased in lamina propria, usually subjacent to basal lamina, although a few IL-2R+ intraepithelial lymphocytes were found: other IL-2R+ cells were deemed to be macrophages (CD68+). These results clearly indicate that in untreated, gluten sensitised subjects the rectal mucosa shows a lymphoplasmacytoid reaction that is responsive to gluten restriction. The absence of neutrophilia suggests that this lesion is not a conventional inflammatory type proctitis, but rather one presumed to be induced by gluten antigen(s) present in the faecal stream--that is, a cell mediated form of response.

CD3 Complex↗
PubMed1993

Rectal epithelial gamma/delta T-lymphocyte responses to local gluten challenge in coeliac disease.

The proportion of intra-epithelial lymphocytes (IEL) that utilize the gamma/delta form of the T-cell receptor (TCR) is increased in coeliac disease, but their function remains unexplained. The response of intra-epithelial lymphocytes to rectal gluten challenge in coeliac and control subjects was studied after a rectal challenge of 2 g of Frazer's fraction III. A marked rise in CD3+ IEL occurred after challenge in the coeliac patients, peaking at 6 h and returning to normal by 48 h, with no significant changes in the gamma/delta TCR+ IEL. The IEL did not significantly change after gluten challenge in the controls. Acute gluten challenge induces infiltration of the rectal mucosa by T cells in coeliac patients, which is not accompanied acutely by increased numbers of gamma/delta TCR+ IEL. This study supports the hypothesis that alpha/beta TCR+ T cells may be of importance in the early response of coeliac patients to local gluten challenge.

Adult↗
PubMed1993

Variations in serum sCD23 in conditions with either enhanced humoral or cell-mediated immunity.

Soluble CD23 (sCD23) is increased by interleukin-4 (IL-4) and decreased by interferon-gamma (IFN-gamma). On the basis of cytokine profiles T-helper (Th) cells may be functionally divided into IL-2- and IFN-gamma-secreting Th1 cells, which are involved in cell-mediated immunity (CMI), and IL-4- and IL-5-producing Th2 cells, which are involved in humoral immunity. Compared with sex-matched controls (median 8.5) we found significantly elevated levels of serum sCD23 in patients with rheumatoid arthritis (median 22.7, P < 0.0002), with the highest levels detected in patients fulfilling an increasing number of the American Association revised criteria for rheumatoid arthritis. Soluble CD23 levels were also significantly raised in autoimmune thyroiditis (median 11.7, P < 0.02) and myasthenia gravis (median 10.4, P < 0.05). In contrast patients with either coeliac (median 6.5) or Crohn's disease (median 5.8) had reduced levels of sCD23 compared to appropriate controls (median 11.8), in both cases significant at P < 0.01. Variations in sCD23 may, therefore, reflect enhanced Th1 activity in the two later conditions in contrast to heightened Th2 activity within the three classical autoimmune conditions.

Antibody Formation↗
PubMed1992

Persistent diarrhea and malnutrition--the impact of treatment on small bowel structure and permeability.

Previous studies using dual sugar permeability tests suggested that damage to the small intestinal mucosa plays an important part in the development of persistent diarrhea in The Gambia. The present study has extended these findings by examining the effect of nutritional rehabilitation on intestinal permeability and mucosal morphology. Intestinal permeability, measured by lactulose:mannitol (L:M) absorption, and mucosal structure, measured by a quantitative, computerised morphologic technique, were evaluated in 20 children before and after such treatment. L:M ratios were high on admission, (0.66 +/- 0.36) and, despite some temporary improvement, did not significantly improve (0.49 +/- 0.30) following rehabilitation for one month. The changes in L:M ratio were largely due to an increase in lactulose absorption, showing that the small intestinal mucosa becomes more "leaky" as a result of nutritional rehabilitation. Although no correlation was found between measures of intestinal permeability and mucosal morphology, nutritional restitution was associated with a significant increase in size of the mucosal crypt cell compartment, but not in villous epithelial volumes during the same period. It is necessary to establish, by further prospective studies, the interval required for full restitution of small intestinal structure and function during treatment for persistent diarrhea.

Anti-Bacterial Agents↗
PubMed1992

Small intestinal mucosal histology in the syndrome of persistent diarrhoea and malnutrition: a review.

Prolonged injury to the small intestinal mucosa is probably the final common pathway by which a variety of noxious influences--nutritional, infective and possibly allergic--perpetuate the syndrome of persistent diarrhoea in children in developing countries. Animal studies have helped to separate the individual effects of malnutrition and diarrhoea on the gut in a way that is not possible in the clinical situation. Early studies in children provided somewhat subjective or semi-quantitative data on intestinal morphology. More recently, the application of computer-assisted quantitative morphological techniques to intestinal mucosae from children with persistent diarrhoea have revealed a spectrum of changes consistent with a cell-mediated immune form of damage. The nature of the antigens that provoke these responses remains to be elucidated. Several reports indicate that in children with persistent diarrhoea clinical severity and prognosis do not necessarily correlate with the degree of small intestinal mucosal damage. Nutritional rehabilitation can be shown to produce a demonstrable improvement in small intestinal crypt cell proliferative activity in children with persistent diarrhoea. It is not yet known for how long nutritional rehabilitation should be continued to ensure complete recovery of the intestinal damage following persistent diarrhoea.

Animals↗
PubMed1992

Gluten, major histocompatibility complex, and the small intestine. A molecular and immunobiologic approach to the spectrum of gluten sensitivity ('celiac sprue').

This article examines associations between gluten, polymorphisms of the major histocompatibility complex, and mucosal pathology representative of the spectrum of gluten sensitivity. Sequences of wheat, rye, and barley prolamins contain recurring tetrapeptide motifs that are predicted to have beta-reverse-turn secondary structure and that, with in vitro assays, appear active. Structural polymorphisms of major histocompatibility complex subloci identify codon switches within the second exon that control the third hypervariable region in the outer domain of the beta chain. Observations of the intestinal response to gluten reveal five interrelated lesions (preinfiltrative, infiltrative, hyperplastic, destructive, and hypoplastic) that are interpretable as cell-mediated immunologic responses. These responses originate in the lamina propria, where a series of antigen-specific inflammatory processes has now been identified. There is no evidence that celiac sprue is a disease of jejunal enterocytes. Furthermore, the role of intraepithelial space lymphocytes in pathogenesis, if relevant, needs further experimental dissection. Also awaiting further definition are polymorphisms of the celiac lymphocyte antigen receptor and their relationship to gliadin oligopeptide(s) and predisposing genes. The nature and basis of nonresponsive celiac sprue require more thoughtful initiatives to elucidate the immunologic mechanism(s) of unresponsiveness and evaluate possible means of reversal. Finally, a more sensible definition of gluten sensitivity (unhampered by qualitative morphological imagery) is ultimately called for in order to accommodate the biomolecular advances addressed in this review.

Amino Acid Sequence↗
PubMed1991

Chronic diarrhea and malnutrition--histology of the small intestinal lesion.

The purpose of this study was to quantitate the jejunal lesion in Gambian children with chronic diarrhea-malnutrition syndrome. There were 40 subjects (20 male, 20 female) with a mean age of 19.7 months. All were severely malnourished, with marasmus in 30, marasmic kwashiorkor in 9, and kwashiorkor in 1. Of subjects tested, 70% were anergic to intradermal challenge with either purified protein derivative or candidin. Jejunal biopsies, performed on every subject after admission to hospital, were studied by computerised image analysis and immunocytochemistry. A spectrum of mucosal changes that varied from "normal" to "flat" was seen. Mucosae with "normal" architecture revealed infiltration of villous epithelium by small lymphocytes, while crypt hypertrophy was invariably present. At the other extreme, the surface epithelium of flat mucosae was less severely infiltrated, although heavy lymphoid infiltrates persisted within crypt epithelium. Immunohistochemical studies revealed that most intraepithelial lymphocytes were of the CD8 + phenotype. Mucosal morphology did not relate to clinical, biochemical, or anthropometric data for each child. These findings are consistent with an intestinal reaction to some environmental antigen (dietary, microbial, or both) of the cell-mediated type. This interpretation is strengthened by the expression of major histocompatibility class 2D locus alloantigens on crypt epithelial cells in the absence of gut-reactive autoantibodies.

Biopsy↗
PubMed1991

Prevalence and treatment of giardiasis in chronic diarrhoea and malnutrition.

To determine the prevalence of giardiasis in Gambian children with chronic diarrhoea and to assess their response to treatment, 31 children with chronic diarrhoea and malnutrition were investigated for giardiasis using a combination of serology (specific antigiardia IgM antibody) and microscopy of faeces and jejunal biopsy specimens. Fourteen of 31 children with chronic diarrhoea had giardiasis compared with only four of 33 healthy age and sex matched control children. Four of 15 malnourished children without diarrhoea were giardia positive. Twenty-three children with chronic diarrhoea were reinvestigated after treatment with metronidazole; giardia was found in 11 of them. These results show that giardia is highly prevalent in children with chronic diarrhoea and malnutrition and that the infection does not respond to standard therapeutic measures.

Animals↗
PubMed1991

Compliance of adolescents with coeliac disease with a gluten free diet.

A cohort of 123 patients with coeliac disease, diagnosed in the first three years of life and followed up for at least 10 years, was reevaluated during the teenage period in terms of compliance with the diet and clinical state. Mucosal structure and lymphocytes were assessed in small intestinal biopsy specimens obtained from 36 subjects, by computerised image analysis. Of these adolescents with coeliac disease, 65% were adhering to a strict gluten free diet, 11.4% were on a gluten free diet but with occasional gluten intake, and 23.6% were on a gluten containing diet. Clinical symptoms occurred more frequently in patients on a gluten containing diet, but not in patients on a semi-strict diet. Occasional intake of small amounts (0.06-2 g/day) of gluten did not produce increased concentrations of antigliadin antibodies but resulted in an appreciably increased crypt epithelial volume and expanded crypt intraepithelial lymphocyte population.

Adolescent↗
PubMed1990

Conformational studies of peptides corresponding to the coeliac-activating regions of wheat alpha-gliadin.

The structures of four peptides corresponding to parts of the coeliac-activating protein A-gliadin were studied by structure prediction and c.d. spectroscopy. Three of the peptides corresponded to parts of the coeliac-activating N-terminal region (residues 3-55, 3-19 and 39-45) and contained two tetrapeptide motifs common to all coeliac-active regions (Pro-Ser-Gln-Gln and Gln-Gln-Gln-Pro). The Pro-Ser-Gln-Gln sequence was also present in the fourth peptide, on the basis of the C-terminal part of the molecule (211-217). These studies showed that beta-reverse turns were the predominant structural feature in all peptides and were predominantly of type I/III in two of the N-terminal peptides and type II in the C-terminal peptide. These turns form when the peptide is dissolved in solvents of low dielectric constant (trifluoroethanol) and high dielectric constant (water and iso-osmotic saline), although their presence in the N-terminal peptides may be masked in the latter solvents due to equilibrium with a poly-L-proline II structure favoured at lower temperatures.

Amino Acid Sequence↗
PubMed1990

Rectal gluten challenge and diagnosis of coeliac disease.

44 patients referred consecutively for jejunal biopsy underwent rectal gluten challenge with 2 g peptic-tryptic digest (Frazer's fraction III; FF3). Rectal biopsy was done before the challenge and 6 h afterwards. Total intraepithelial lymphocytes (IEL) overlying a 10(4) micron 2 test area of muscularis mucosae were quantified by computerised image analysis. The subjects comprised 21 controls with disorders other than coeliac disease and 23 patients (14 treated, 9 untreated) with coeliac disease diagnosed by strict jejunal biopsy gold standard criteria. There was no difference between the groups in IEL numbers before challenge. Coeliac disease patients but not controls responded to FF3 with a rise in mucosal IEL (median 60.5% rise for treated, 63.0% for untreated). There was no response to challenge with beta-lactoglobulin in coeliac disease or control subjects. When a predefined, post-challenge IEL "predictive index" of more than 10% above baseline was used to indicate a diagnosis of coeliac disease, it gave a sensitivity of 90% and specificity of 91% (95% confidence intervals 78-93%). Rectal gluten challenge is a simple, safe, and reliable test of gluten sensitivity, both as a screening test for untreated coeliac disease and as a confirmatory test in patients with treated coeliac disease.

Celiac Disease↗
PubMed1990

Cellular basis for defective electrolyte transport in inflamed human colon.

Electrolyte transport pathways in distal colonic mucosa from patients with noninflammatory and inflammatory (ulcerative colitis, Crohn's colitis) disease of the large bowel were studied in vitro with electrophysiological techniques. Noninflamed tissues exhibited substantial amiloride-sensitive electrogenic sodium transport. In contrast, inflamed but structurally intact tissues exhibited only a modest degree of electrogenic sodium transport, significant increases in total tissue conductance and apical membrane conductance, and a 100% increase in the arachidonic acid content of the cell membrane fraction of mucosal homogenates. Replacement of chloride with gluconate decreased total tissue conductance to a greater extent in inflamed than in noninflamed tissues, and total tissue conductance was higher in inflamed than in noninflamed tissues in the presence of transepithelial potassium and sodium gradients, suggesting enhanced mucosal "leakiness" to anions and cations in acute colitis. Apical addition of nystatin virtually abolished amiloride-sensitive apical sodium uptake in both groups, indicating that the ionophore formed channels in the apical membrane of noninflamed and diseased mucosa. Additional studies showed that mucosal inflammation decreased maximal activity of the basolateral sodium pump by 76%. Thus, defects in the biophysical properties of colonic epithelial cell membranes are likely to be important factors in the pathogenesis of diarrhea in ulcerative and Crohn's colitis.

Adult↗