Exocrine pancreatic insufficiency following esophagectomy.

Weight loss following esophagectomy is a management challenge for all patients. It is multifactorial with contributing factors including loss of gastric reservoir, rapid small bowel transit, malabsorption, and adjuvant chemotherapy. The development of a postoperative malabsorption syndrome, as a result of exocrine pancreatic insufficiency (EPI), is recognized in a subgroup of patients following gastrectomy. This has not previously been documented following esophageal resection. EPI can result in symptoms of flatulence, diarrhea, steatorrhea, vitamin deficiencies, and weight loss. It therefore has the potential to pose a significant level of morbidity in postoperative patients. There is some evidence that patients with proven EPI (fecal elastase-1 < 200 µg/g) may benefit from a trial of pancreatic enzyme replacement therapy (PERT). We observed symptoms compatible with EPI in a subgroup of patients following esophagectomy. We hypothesized that this was contributing to malabsorption and malnutrition in these patients. To investigate this, fecal elastase-1 was measured in postoperative patients, and in those with proven EPI, a trial of PERT was commenced in combination with specialist dietary education. At routine postoperative follow-up, which included assessment by a specialist dietitian, those patients with symptoms suggestive of malabsorption were given the opportunity to have their fecal elastase-1 measured. PERT was then offered to patients with fecal elastase-1 less than 200 µg/g (EPI) as well as those in the 200-500 µg/g range (mild EPI) with more severe symptoms. Fecal elastase-1 was measured in 63 patients between June 2009 and January 2011 at a median of 4 months (range 1-42) following surgery. Ten patients had fecal elastase-1 less than 200 µg/g, and all had failed to maintain preoperative weight. All accepted a trial of PERT. Nine (90%) had symptomatic improvement, and seven (70%) increased their weight. Thirty-nine patients had a fecal elastase-1 in the 200-500 µg/g range. Twelve were given a trial of PERT based on level of symptoms, five (42%) reported an improvement in symptoms, but only two (17%) gained weight. Our early results support the observation that EPI is a factor contributing to postoperative morbidity in patients recovering from esophagectomy and that these patients can benefit from a trial of PERT. Our study has limitations, and a formal trial is required to evaluate the impact of EPI and PERT following esophagectomy. Currently, our practice is to measure fecal elastase-1 in any patient with unexplained weight loss or symptoms of malabsorption. In patients with proven EPI or those who are symptomatic with mild EPI, a trial of PERT should be offered and symptoms reassessed.

Lymphocytes of the intestinal mucosa of chickens.

Examination, by light and electron microscopy, of the morphology and the staining properties of intraepithelial lymphocytes from the intestine of the chicken revealed a population of lymphoid cells, of which a proportion (up to 20%) is granulated. The majority of cells were immunoreactive with anti-T cell serum and can therefore be considered to be related to T-lymphocytes, but they did not proliferate when cultured with phytohaemagglutinin. The granulated cells were identical to those previously designated globule-containing leukocytes, but were distinct from mast cells in their morphology, staining reactions and the stability of the granules in different fixatives and buffers.

The effect of immunity on the early events in the life-cycle of Eimeria tenella in the caecal mucosa of the chicken.

A comparison was made between the early events (asexual stages) in the life-cycle of Eimeria tenella in specifically immunized and control chickens. Particular attention was paid to the quantitative aspects and to the transport of sporozoites within intra-epithelial lymphocytes (IEL) from the enterocytes of the surface epithelium to the enterocytes of the crypts. There was a moderate decrease in the number of parasites initially seen in the mucosa of the immune birds, suggesting that some of the effects of immunity are exerted before penetration of the surface enterocytes, but the reduction in the numbers of developing parasites was more marked. This latter effect was due, at least partly, to failure of transfer of sporozoites from IELs to crypt enterocytes. These findings are discussed in relation to the efficacy of the immunity induced.

Marek's disease in turkeys: the induction of lesions and the establishment of lymphoid cell lines.

The inoculation of turkeys with large doses of a virulent strain of Marek's disease virus (GA strain), but not of two other virulent strains (HPRS-16 and JM), was found to induce a disease resembling Marek's disease of the chicken. The most prominent lesions were lymphocytic leukaemia and lymphoid and reticular hyperplasia in the spleen and the liver. These developed after a prolonged latent period and the early histological changes (lymphoid cell destruction and reticuloendothelial cell hyperplasia) reported in chickens were not observed. Twelve cell lines were established from suspensions of spleen cells or of buffy coat cells from infected turkeys. These cells expressed both Marek's disease tumour-associated surface antigen and T-cell antigens. The cells carried the Marek's disease virus genome and when inoculated into chickens induced typical Marek's disease lymphomas. Nine of the cell lines were infected with an avian leukosis virus, but three lines were free of such infection. All cell lines had normal turkey karyotypes.

Invasion of chicken caecal and intestinal lamina propria by crypt epithelial cells infected with coccidia.

The development of second generation schizonts of Eimeria necatrix and E. tenella was studied with the electron microscope. Invasion of the crypt epithelial cells by merozoites of the first generation schizonts caused changes in the morphology of the infected cells and stimulated their migration into the lamina propria through breaks which appeared in the basement membrane of the crypts. Second generation schizonts developed in the lamina propria within these crypt cells whose epithelial origin was confirmed by their interconnection by desmosomes and tight junctions and by their possession of characteristic microvilli. A comparison is made between this invasion of the lamina propria by parasitized cells and invasion of connective tissue by malignant epithelial cells; the possible mechanisms involved are discussed.

Mucosal transport of Eimeria tenella in the cecum of the chicken.

A study of the early life history of Eimeria tenella with the electron microscope confirmed that sporozoites do not directly enter the enterocytes of the crypts, in which they develop, but are carried there by host cells. However, these cells are not macrophages, as previously thought, but intraepithelial lymphocytes. The evidence presented demonstrates that sporozoites first penetrate surface enterocytes and then enter intraepithelial lymphocytes that leave the epithelium, pass through the lamina propria and enter the crypts.

Parasite-host relationships during the development of Eimeria dispersa Tyzzer 1929, in the turkey (Meleagris gallopavo gallopavo) with a description of intestinal intra-epithelial leucocytes.

An electron microscopical study was made on the development of Eimeria dispersa in the small intestine of the domestic turkey. Turkey poults, 10-14 days of age, were inoculated with oocysts and pieces of intestinal tissue were fixed at intervals between 3.5 and 114 h after inoculation. Sporozoites were occasionally seen in enterocytes but more often in 'pale' cells closely resembling lymphocytes. These cells were insinuated between enterocytes and in this study are referred to as intestinal intra-epithelial leucocytes (IEL). Maturation of the first-generation of schizogony occurred in this type of cell. Other generations of schizonts and gametogony occurred in epithelial cells and were characterized by the presence of 'spines' arranged around the parasitophorous vacuole extending into the cytoplasm of the host cell. A limited study of the parasite in the Bobwhite quail, Colinis virginianus, showed that development occurred in similar cells to those of the turkey. The 'spines', which were characteristic of later stages of E. dispersa in the turkey, were also present in this host and seemed to be a characteristic of E. dispersa, not of the host species.

Idiopathic polyneuritis in SPF chickens.

Paralysis due to peripheral neuritis occurred sporadically in a flock of Rhode Island Red chickens over a period of 8 years and is named idiopathic neuritis (IP). The flock was housed in isolators and free from many common pathogens including all known neurotropic viruses of chickens. The pathology of the nerve lesions, including their ultrastructure, is described and comparisons made with the lesions of Marek's disease and experimental allergic neuritis in chickens. Demyelination with invasion of nerve fibres with lymphocytes and macrophages occurs in all three diseases but there are differences in lesion distribution and intensity of cellular infiltration. The closest similarity is between the lesions of IP and the B-type lesions of Marek's disease. Attempts to isolate a cytopathic virus and to transmit the disease by inoculation failed to demonstrate an infectious causal agent. An autoimmune response to normal nerve is suggested as the most likely aetiology amongst several alternatives. The heritability of IP is not established, but the disease has not been detected in a light Sussex flock maintained under similar conditions.

Ultrastructure of the central nervous system in Marek's disease and the effect of route of infection on lesion incidence in the central nervous system.

The ultrastructure of the lesions of the central nervous system (CNS) of chickens was examined at intervals after intra-abdominal inoculation of Marek's disease virus (MDV). No transient paralysis occurred. Peri-vascular accumulations of lymphocytes and macrophages (cuffing) were accompanied by invasion of the CNS by these blood-borne leukocytes in the most severe lesions. Only minor damage to axons, myelin or glial cells was detected and no structural evidence for viral replication was observed. Intracerebral inoculation of cell-free MDV induced similar lesions in the CNS and there was no evidence for local exacerbation of their severity, although a few chickens developed transient paralysis. It is concluded that replication of MDV in the CNS is unlikely to be the direct cause of the CNS lesions.

Presence of a complete endothelial barrier between lymph and lymphoid tissue in the lumbar lymph nodes of the duck (Anas platyrhynchos).

The ultrastructure of the lumbar lymph nodes of the domestic duck is described and compared with published accounts of mammalian lymph nodes. The barrier to cell migration between lymphoid tissue and lymph is more formidable in the duck than in the mammal. In the duck the lymphatic endothelium lining the lymph spaces is continuous and bonded with desmosomes whereas in the mammal it is unbonded and fenestrated. In both types of node there are filtering zones and areas of dense lymphatic tissue but their topographical organisation differs. There is no cortex or medulla in the duck lymph node and filtration occurs in extensive lymphatic spaces traversed by numerous trabeculae to which are attached rounded phagocytic macrophages. Dense lymphoid tissue is scattered throughout the node, suspended by trabeculae or attached to the capsule and there are blood vessels analogous to the post capillary venules of mammalian nodes where lymphocytes migrate between blood and lymphoid tissue.

The effect of virus dose on the development of Marek's disease in two strains of chickens.

The effect of inoculating different doses of Marek's disease virus on the consequent lymphocyte-associated viraemia titres, survival time and mortality was studied in two strains of chickens, one highly susceptible (a strain of Rhode Island Red) and one moderately resistant (a strain of Light Sussex) to Marek's disease. In both strains an increase in the infecting dose of virus increased the ensuing viraemia, and there was an inverse relationship between virus dose and survival time. There was a negative correlation between viraemia titres and survival time. The modulation of infecting dose had no effect on overall mortality among the susceptible, Rhode Island Red strain, chickens, but did influence the mortality of the Light Sussex strain chickens. It was suggested that the outcome of infection within an individual may be determined by a rather subtle interaction between the infection and transformation of a limiting number of target cells and an immune response directed against such infected or transformed cells, and that in different breeds of chickens these two factors may differ in importance.

Chronological study of ultrastructural changes in the peripheral nerves in Marek's disease.

A chronological study was made of the ultrastructural changes in peripheral nerves following inoculation of 1-day-old chicks with a neurogenic strain of Marek Disease virus. No virus particles were found in nerves. Cellular infiltration of nerves was detected as early as 5 days after inoculation and by 3 weeks some nerves contained proliferative lesions which possessed many of the ultrastructural features characteristic of normal, reactive lymphoid tissue. About 4 weeks after inoculation, coinciding with the onset of neurological signs, areas of widespread demyelination appeared within these lesions; lymphocytes and macrophages penetrated and destroyed the myelin sheath, but spared Schwann cells and most axons. Later oedematous, sparsely infiltrated B type lesions were observed, some of which contained demyelinated nerve fibres undergoing repair; these were therefore a stage in the regression of the proliferative lesions. Our observations do not favour the hypothesis that cellular infiltration of nerves in Marek's disease is the direct result of auto-sensitization to normal myelin. They are consistent with the hypothesis that demyelination is a secondary feature and that the primary lesions are preferential sites for immune demyelination.

Haemopoietic cells in peripheral nerves of SPF chickens.

Foci of haemopoiesis were found in the peripheral nerves of SPF Rhode Island Red chickens and conventionally reared Brown Leghorn chickens. They contained cells which closely resembled the development stages in the bone marrow of erythrocytes, heterophil leukocytes or thrombocytes, but did not include lymphocytes. When birds from these flocks are used to study neuropathological disease, ectopic haemopoiesis in nerves must be distinguished from pathological lesions.

Morphological distinction between different H serotypes of Escherichia coli.

The structure of the flagellar filaments of 50 Escherichia coli strains, each with a different H antigen, was examined. Although the flagella within each strain were structurally identical, there was variability in flagellar surface pattern between strains with differrent H antigens. Investigation of additional strains confirmed that flagella structure was the same in all strains having the same H antigen. In three pairs of strains with cross-reacting H antigens, the antigenic relatedness was associated with identical flagella structure.

Comparison of the flagellins from different flagellar morphotypes of Escherichia coli.

The molecular weights of the flagellins of 13 strains of Escherichia coli, each with a different H antigen, were estimated using polyacrylamide gel electrophoresis. In each case only one major polypeptide was demonstrated, although some strains possessed apparently sheathed flagella. Considerable differences in the molecular weight of flagellin accompanied the previously described structural differences between flagella from strains with different H antigens. The relationship between flagellar diameter and the molecular weight of the corresponding flagellins was similar for both unsheathed and apparently sheathed flagella. Crosss-polymerization occurred between seed consisting of fragment of unsheathed flagella and flagellin solution from apparently sheathed flagella and vice versa. Co-polymerization of flagellin from unsheathed flagella and flagellin from apparently sheathed flagella was also demonstrated. These polymerization experiments indicate that the assembly pattern of flagellin molecules is probably the same in all E. coli flagella. The above and other evidence suggests that there is no true sheath, but that the differences in flagellar surface structure between different E. coli flagella are the result of differences in the superficial parts of the flagellin molecules.