Michael N. Marsh

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.

Morphology of the mucosal lesion in gluten sensitivity.

Gluten sensitivity is associated with a spectrum of mucosal lesions, arbitrarily termed pre-infiltrative, infiltrative-hyperplastic, flat-destructive and atrophic-hypoplastic. Histologically and immunohistologically these lesions are all compatible with T-cell-driven events operative at a local mucosal level. They are classifiable either in terms of antibody titres (pre-infiltrative) (see Chapter 10) or by the characteristic disposition of IELs throughout the surface and crypt epithelium. From in-vivo challenges, it has been demonstrated: (i) that all these lesions comprise a dynamically interrelated series of events, culminating in the severe flat-destructive lesion; and (ii) that gluten evokes a dose-responsive infiltration of IELs (CD3+ CD8+ and TCR alpha beta + or gamma delta +) into the epithelium. Apart from that, little is known of the functions of IELs; it is possible they may have little to do with the evolving mucosal pathology of gluten sensitivity. Increasing work seems to support a view, proposed from this laboratory over 10 years ago, that the immune-mediated responses in jejunal tissue in gluten sensitivity arise in the lamina propria, in association with DR+ macrophages and an abundance of CD4(+)-activated lymphocytes. Many other inflammatory consequences flow from these interactions, involving activation of mast cells, eosinophils and neutrophils, elaboration of cytokines and other products of inflammation, and increased hyperpermeability of the microvasculature with upregulation of adhesion molecules. The result is a doubling of lamina propria volumes in the severe flat lesion. Evidence is also given to show that measurable changes in lamina propria inflammation occur with the infiltrative-hyperplastic lesion. Symptomatology is not related to the degree of proximal mucosal pathology, but to the extent of the mucosal lesion. Data, although scanty, suggests that lesional pathology involves only 30-50% of the entire small bowel mucosa. Thus, most patients, irrespective of proximal mucosal damage, have latent (or asymptomatic) gluten sensitivity. Symptom development requires additional environmental triggers, of which infection is a major contributor. It should also be noted that, while these various environmental triggers may precipitate symptomatology, they do not advance the severity of the mucosal lesion.

The Oxford submicron nuclear microscopy facility

Abstract This paper describes the unique nuclear microprobe facility now established in the University of Oxford. The system, which uses a dedicated small accelerator, operates on a regular daily basis, therefore the emphasis of the design has been on achieving reliable, high-quality performance while minimising overheads of alignment in the focusing system and off-line data processing. The beam-optical system from the ion source to the final lens is described. The final lens has been specially developed to have negligible sextupole-field contamination which allows submicron operation using simple alignment procedures. The system uses up to three beam lines with specialised target chambers. These are described briefly. The data acquisition system uses distributed processing with a VMEbus 68020 microcomputer system handling collection and on-line sorting of data from up to six detectors, a graphics workstation for operator interfacing and a mainframe computer for archiving and off-line processing of data. The components of the system communicate via Ethernet and a low-failure-rate/highthroughput communications protocol has been developed. The archiving procedures are designed to handle high volumes of data (up to 100 Mb per day) with efficient data compression, transparent recall of recent data and simple restoration of archived data.

MgF3− as a Transition State Analog of Phosphoryl Transfer

The formation of complexes between small G proteins and certain of their effectors can be facilitated by aluminum fluorides. Solution studies suggest that magnesium may be able to replace aluminum in such complexes. We have determined the crystal structure of RhoA.GDP bound to RhoGAP in the presence of Mg(2+) and F(-) but without Al(3+). The metallofluoride adopts a trigonal planar arrangement instead of the square planar structure of AlF(4)(-). We have confirmed that these crystals contain magnesium and not aluminum by proton-induced X-ray emission spectroscopy. The structure adopted by GDP.MgF(-) possesses the stereochemistry and approximate charge expected for the transition state. We suggest that MgF3(-) may be the reagent of choice for studying phosphoryl transfer reactions.

When is a coeliac a coeliac

It should be recognized that these guidelines should not be deemed inclusive of all proper methods of care or exclusive of methods of care reasonably directed to obtaining the same results. The ultimate judgement regarding the propriety of any specific guideline must be made by the physician in light of all the circumstances presented by the individual patient.

Studies of Intestinal Lymphoid Tissue: IX. Dose-Dependent, Gluten-Induced Lymphoid Infiltration of Coeliac Jejunal Epithelium

Jejunal biopsy specimens from coeliac patients who had received small, oral doses (100-1500 mg) of a peptic-tryptic gluten digest were analysed by morphometric methods. An increase in the total number of surface epithelial lymphocytes, maximal at 12 h after challenge, was dose-dependent, the mean percentage rise at this time being 53% (p less than 0.005), 44% (p = 0.01), and 25% (p greater than 0.05) with 1500, 1000, and 500 mg of gluten digest, respectively. This effect was not accompanied by any increased mitotic activity or blast transformation among the infiltrating lymphocytes, nor was there any demonstrable alteration in mucosal structure-that is, reduction in surface or increase in crypt epithelial volumes. The results of this controlled morphometric analysis indicate that oral gluten challenge causes an increase in the lymphocyte population of surface epithelium in coeliac disease but that this effect does not necessarily result in mucosal damage.

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:man-nitol (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.

Microscopic enteritis: Bucharest consensus

Microscopic enteritis (ME) is an inflammatory condition of the small bowel that leads to gastrointestinal symptoms, nutrient and micronutrient deficiency. It is characterised by microscopic or sub-microscopic abnormalities such as microvillus changes and enterocytic alterations in the absence of definite macroscopic changes using standard modern endoscopy. This work recognises a need to characterize disorders with microscopic and submicroscopic features, currently regarded as functional or non-specific entities, to obtain further understanding of their clinical relevance. The consensus working party reviewed statements about the aetiology, diagnosis and symptoms associated with ME and proposes an algorithm for its investigation and treatment. Following the 5(th) International Course in Digestive Pathology in Bucharest in November 2012, an international group of 21 interested pathologists and gastroenterologists formed a working party with a view to formulating a consensus statement on ME. A five-step agreement scale (from strong agreement to strong disagreement) was used to score 21 statements, independently. There was strong agreement on all statements about ME histology (95%-100%). Statements concerning diagnosis achieved 85% to 100% agreement. A statement on the management of ME elicited agreement from the lowest rate (60%) up to 100%. The remaining two categories showed general agreement between experts on clinical presentation (75%-95%) and pathogenesis (80%-90%) of ME. There was strong agreement on the histological definition of ME. Weaker agreement on management indicates a need for further investigations, better definitions and clinical trials to produce quality guidelines for management. This ME consensus is a step toward greater recognition of a significant entity affecting symptomatic patients previously labelled as non-specific or functional enteropathy.

Studies of intestinal lymphoid tissue. XII. Epithelial lymphocyte and mucosal responses to rectal gluten challenge in celiac sprue

The immunopathologic, structural, and functional changes within rectal mucosa of known celiac sprue subjects were quantitated during local challenge with a peptic-tryptic digest of gluten. In the celiac sprue patients challenged with 2 g of digest, major effects occurred in lamina propria, submucosa, and local microvasculature. The lamina propria swelling was biphasic, starting 1-2 h after challenge with widespread extravascular deposition of fibrinogen, indicative of increased microvascular permeability, receding by 24 h postchallenge. A rapid fall in mast cells together with granule discharge suggested their involvement in this response. The late-phase swelling (48-72 h) was preceded by a rapid influx of neutrophils and basophils, the latter showing evidence of degranulation beyond 72 h. Reestablishment of vessel lumina, a rise in mast cells, and loss of neutrophils indicated tapering of the inflammatory cellular cascade by 96 h. Lymphocytes, first seen to enter the lamina by 2 h postchallenge, increased progressively, thereby resulting in substantial infiltration between 36 and 96 h. A marked rise in epithelial lymphocytes, maximal at 6-8 h, waned by 24 h. Volumes of surface and crypt epithelium remained constant throughout. In another challenge series with 4 g of gluten digest, electrical potential difference across rectal mucosa decreased significantly 12 h postchallenge, but the associated decreases in net sodium and chloride absorptive fluxes were insignificant. It is concluded that rectal mucosa is sensitized to gluten in celiac sprue disease and thus offers a promising and convenient in vivo substrate for investigative and diagnostic purposes.

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.