Ian C. Roberts-Thomson

Manometric Disorders in Patients With Suspected Sphincter of Odds Dysfunction

Sphincter of Oddi (SO) manometry was conducted in 48 subjects who had previously undergone cholecystectomy. Ten of these subjects had no detectable biliary or pancreatic disease and served as controls. The other 38 patients were presumed to have SO dysfunction and had presented with episodes of severe biliary-type pain with either dilatation of the bile duct on a retrograde cholangiogram, transient changes in liver function tests, or both of these abnormalities. A triple-lumen low-compliance manometric system was used to record the SO basal pressure, SO phasic contraction amplitude, SO wave frequency, direction of wave propagation, and SO response to intravenously administered cholecystokinin-octapeptide 20 ng/kg. Satisfactory manometric recordings were obtained from 32 of 38 patients and of these, 25 patients showed one or more abnormalities when compared with data from the 10 controls. The abnormalities included excess of retrograde contractions (12), high frequency of SO phasic contractions (11), elevation of the SO basal pressure (8), and paradoxical cholecystokinin-octapeptide response (10). The study has demonstrated a spectrum of manometric abnormalities in the SO of patients with suspected SO dysfunction.

Giardiasis In Mice: I. Prolonged infections in certain mouse strains and hypothymic (nude) mice

The natural history of Giardia muris has been studied in inbred mouse strains and hypothymic (nude) mice derived from a specific pathogen-free facility. Although giardiasis was readily established in several mouse strains, marked variation was observed in the time course of spontaneous elimination of the parasite. During a 10-week study, fecal excretion of Giardia cysts remained relatively constant in C3H/He mice, but decreased at a variable rate in other mouse strains. Resistance to reinfection was greater in strains in which the duration of primary infection was relatively short. Hypothymic (nude) mice derived from a strain showing a relatively rapid elimination of Giardia (BALB/c) maintained a stable infection with high cyst counts. Nude mice reconstituted with lymphoid cells from syngeneic thymus-intact mice showed a progressive reduction in cyst excretion and reconstitution with limited numbers of lymphoid cells from thymus-intact mice previously exposed to Giardia accelerated resolution of infection. In nude mice, giardiasis was associated with a reduction in the villus-crypt ratio of jejunal mucosa, but the degree of change was greater in nude mice reconstituted with lymphoid cells. This Giardia model involving inbred strains and nude mice permits further dissection of the function of thymus-derived cells in intestinal immune responses and induction of changes in small bowel morphology.

Analysis of Infection Characteristics and Antiparasite Immune Responses in Resistant Compared with Susceptible Hosts

Variations in susceptibility or immune responsiveness to parasites, and variations in the consequences of parasitic infection, are readily detected in natural host populations (Wakelin 1978a). Variable outcomes of parasitic infection and disease are predictable bearing in mind that genetic heterogeneity of hosts a«c/parasites is essential for evolutionary survival of either party. It has been argued that immunological events have been the key (but certainly not the only) ingredient in the evolutionary development of balanced host-parasite relationships (Sprent 1959, Burnet & White 1972, and reviewed in Mitchell 1979a,b). The animal breeder expects to exploit any high hereditability of resistance to parasites and searches for linked characteristics which are detected readily, or correlative immune responses, to be used in selection programs. Similarly, the experimental immunoparasitologist expects to exploit at least some genetically-based variations in host resistance to pinpoint immunological effector mechanisms and target parasite antigens (and to identify genetic aspects of expression oi both) which are necessary or sufficient for host protection. Of particular interest are differences in (1) disease manifestations, (2) levels and duration of primary infection, (3) responsiveness to vaccination, (4) responsive-

Giardiasis in mice: analysis of humoral and cellular immune responses to Giardia muris.

Summary Humoral and cellular immune responses have been evaluated in two inbred strains of mice which differ markedly in their susceptibility to infection with Giardia muris. Serum IgG and IgA antibody levels and IgA levels in intestinal washes were determined by a solid‐phase radioimmunoassay using G. muris antigen prepared by sonication of trophozoites, while cell‐mediated immunity was assessed by a radiometric ear‐assay for delayed‐type hypersensitivity. Following infection of BALB/c mice (resistant) and C3H/He mice (susceptible), the IgG and IgA antibody levels in serum progressively increased over the period of study with C3H/He mice having significantly higher titres of IgA antibodies than BALB/c late in the infection. Systemic immunization with G. muris trophozoites resulted in high titres of IgG antibodies in the serum. IgA antibodies were detected in intestinal washes 2 weeks after infection with a subsequent fall in levels in BALB/c mice but a progressive increase in levels in C3H/He mice. Prior immunization resulted in IgA antibodies being detected earlier in the intestinal washings after a challenge infection. Delayed‐type hypersensitivity to G. muris antigens could not be detected during an infection but a positive response was elicited following antigen priming in mice pretreated with cyclophosphamide. The immune responses evaluated in this study were assessed using a whole G. muris trophozoite sonicate and variations in the quantitative aspects of the responses did not account for observed differences in the course of infection in the two strains of mice.

Morphometric Evaluation of Duodenal Biopsies in Celiac Disease

OBJECTIVES:The Marsh classification is a semiquantitative method for the diagnosis and monitoring of changes in duodenal biopsies in celiac disease. We have explored the possibility that quantitative changes in villous area and crypt length (morphometry) may provide better information on changes in duodenal morphology, particularly after the introduction of a gluten-free diet.METHODS:We measured villous height, apical and basal villous widths, and crypt length in 57 adults with celiac disease and 83 control subjects. Villous area was calculated as a trapezoid approximation. Serial changes in villous area and crypt length were determined at regular intervals for up to 4 years after the introduction of a gluten-free diet. Morphometric changes were also correlated with Marsh grade, self-reported adherence to a gluten-free diet, and changes in celiac serology.RESULTS:The gluten-free diet resulted in a progressive increase in villous area and a progressive decrease in crypt length. Morphometric improvement reached a plateau after 6–12 months with mean villous area attaining a value approximately half that of control subjects. Morphometric data were more sensitive than Marsh grade. Improvement in morphometric indices was significantly associated with the disappearance of anti-endomysial IgA antibody but not with dietary compliance.CONCLUSIONS:Morphometry is a sensitive way to document changes in duodenal biopsies in celiac disease. In adults treated with a gluten-free diet, it is uncommon for villous area to return to values observed in control subjects, but morphometric improvement is associated with the disappearance of anti-endomysial IgA antibody.

Spontaneous improvement in pancreatic function in chronic pancreatitis.

Three women with chronic pancreatitis who were observed for 4–29 years showed spontaneous improvement in exocrine function as assessed by symptoms and by reduction in fecal excretion of fat. One patient had a reduction in the severity of diabetes mellitus, while another showed a progressive increase in the maximum bicarbonate concentration in duodenal juice after the intravenous injection of secretin. Improvement in pancreatic function followed cessation of alcohol in two patients in whom chronic pancreatitis was associated with alcohol abuse.

Examination of strategies for vaccination against parasitic infection or disease using mouse models.

There are currently no prophylactic or therapeutic vaccines against parasites of medical importance, the parasitic infections with major public health consequences being concentrated in tropical, less industrially developed countries. However, a limited number of living vaccines against economically important parasites is available in veterinary medicine, and vaccination efficacy of crude antigen preparations has been demonstrated time and again in laboratory models involving helminth, protozoan, and arthropod parasites (Clegg and Smith, 1978; Cox, 1978; Pery and Luffau, 1979; Murray et al., 1979; Mitchell, 1982a; Mitchell and Anders, 1982; Rickard and Williams, 1982).

Wnt Ligand Expression and Regulation of Stem Cells During Postnatal Growth of the Small Intestine in Rats

Background: The sequential proliferation, lineage-specific differentiation, crypt-villus migration, and cell death of the epithelial cells of the intestinal mucosa is tightly regulated by regulatory peptides, differentiation signals, and luminal stimuli, including nutrients and pathogenic/commensal organisms. Despite its importance for understanding normal homeostasis and pathogenesis of disease states, the intracellular signal transduction mechanisms involved remain incompletely understood. Here, we tested the hypothesis that PKD1 plays a key role in intestinal crypt cell proliferation In Vivo. Results: To clarify the role of PKD1 in intestinal epithelial cell proliferation In Vivo, we generated transgenic mice that express elevated PKD1 protein in the distal small intestinal and proximal colonic epithelium. The catalytic activity and multi-site phosphorylation (Ser744, Ser748 and Ser916) of PKD1 was strikingly higher in extracts from ileal mucosa of transgenic mice as compared with non-transgenic littermates. These results indicate that transgenic PKD1 is functional in the intestinal epithelium. PKD1 signaling stimulated intestinal cell proliferation, as shown by detection of 5-bromo-2-deoxyuridine (BrdU) incorporated into the cell nuclei of crypt cells of the ileum and proximal colon, where PKD1 protein is maximally expressed. Our results demonstrated a highly statistically significant increase (p<0.005) in DNA synthesizing cells in the crypts of the PKD1 transgenic mice as compared with non-transgenic littermates. In the intestine, normal cell numbers are maintained by balancing rates of cell proliferation, differentiation, migration and apoptosis. Consequently, we determined whether transgenic PKD1 leads to a change in tissue architecture, manifested by an increase in the size and total number of epithelial cells in the crypts. We measured crypt height (in micrometer and cell number) and crypt circumference (in micrometer and cell number) in histological sections of control and PKD1 transgenic mice. The data was used to calculate the size of individual cells and the total number of cells per crypt. Our results show a significant increase in the depth (either in μm or in number of cells) and in the total number of cells per crypt in the transgenic PKD1 mice as compared with the nontransgenic littermates (276 total cells per ileal crypt in transgenic mice versus 192 in nontransgenic mice; p< 0.005). These results indicate that the expression of the PKD1 transgene led to a marked increase (44%) in the total number of intestinal epithelial cells per crypt. Conclusion: Transgenic PKD1 expression increases the number of cells per crypt by stimulating the rate of crypt cell proliferation. These results support the hypothesis that PKD1 signaling plays a role in a pathway leading to proliferation in intestinal epithelial cells.