1. A study was conducted on the pattern of development of the intestinal mucosa of the Steggles x Ross (F1) strain of broiler chickens reared on a commercial starter diet. The mechanisms underlying the structural changes were also assessed. 2. In relation to body weight, small intestinal weight peaked at 7 d of age and declined subsequently. There was also a reduction in the relative weights of the gizzard and yolk sac with age. The length of the small intestine and its regions increased with age. 3. Crypt depth increased with age in the duodenum and jejunum while villus height increased significantly with age in all three regions of the small intestine. There were also significant changes in apparent villus surface area in the three regions, while interactions between age and intestinal region were significant in the case of crypt depth and villus height. 4. There were significant differences between the age groups in the mucosal protein content of jejunal and ileal homogenates, both tending to peak at 7 d of age. The DNA content of the intestinal mucosa declined with age in the three regions of the small intestine. While there was an increase in RNA content in the duodenum and ileum, there was a reduction in the jejunum. 5. Protein: DNA ratio increased between hatch and 21 d of age in all intestinal regions. Protein: RNA ratio decreased with age in the duodenum and ileum but increased in the jejunum. There were significant increases in RNA: DNA ratio in the duodenum and ileum but no changes were observed in the jejunum. The interactions between age and intestinal region were significant for all biochemical indices assessed. 6. At all ages, enterocyte proliferation at the jejunum was completed and quantifiable within 1 h of administration of 5-bromo-2'-deoxyuridine (BrDU). Subsequent assessment revealed an increase in crypt column count and number of BrDU-labelled cells. The rate of cell migration increased with age while there was a decline in the distance migrated in proportion to mucosal depth. The estimated life-span of enterocytes and time spent by enterocytes in the crypt varied with age. In d-old and 7-d-old chicks, migration was complete or nearly complete within 96 h of cell birth. 7. Although the intestinal mucosa of the strain was structurally developed at hatch, there was much change in structure with age, especially over the first 7 d post hatch. The rate of development was most rapid in the jejunum but the other regions are also important, on account of villus height or relative length of the region.
Mucins possess potential binding sites for both commensal and pathogenic organisms and may perform a defensive role during establishment of the intestinal barrier. To observe the effects of bacteria on intestinal goblet cell mucin production during posthatch development, differences in the small intestine of conventionally reared (CR) and low bacterial load (LBL) broiler chicks were examined. Jejunal and ileal goblet cells were stained with either periodic acid-Schiff stain or high iron diaminealcian blue pH 2.5 to discriminate among neutral, sulfated, and sialylated acidic mucins. Total goblet cell numbers and morphology of goblet cells containing neutral and acidic mucins did not differ significantly between CR and LBL birds. However, significant differences in acidic mucin composition from primarily sulfated to an increase in sialylated sugars at d 4 posthatch were observed in CR chicks, with greater numbers of jejunal and ileal goblet cells displaying this mucin type (CR, 0.5 +/- 0.1 x 10(3) cells/mm(2); LBL, 0.04 +/- 0.02 x10(3) cells/mm(2)). This change in mucin profile in response to bacterial colonization suggests a potential role as a protective mechanism against pathogenic invasion of the intestinal mucosa during early development.
A study was conducted to evaluate the response of broiler chickens to a commercial synthetic mannan oligosaccharide, Bio-Mos 2 (BM), included in sorghum/lupin-based diets at 0.0, 1.0, 3.0 or 5.0 g kg À1 diet. The diets were fed between 7 and 28 days of age, and both the gross response and mechanisms involved were evaluated. The highest level of BM in the diet resulted in longer (P < 0.01) jejunal villi than those observed at other levels of supplementation. The RNA content of the ileal mucosal homogenate was signi®cantly greater (P < 0.05) in chicks raised on diets supplemented with 3.0 and 5.0 g BM kg À1 diet than in other groups. The protein/DNA ratio of the jejunal mucosal homogenate was also higher (P < 0.05) in chicks fed the 1.0 g BM kg À1 diet than in chicks fed the other diets. The protein/RNA and RNA/DNA ratios in ileal homogenates were signi®cantly (P < 0.01) in¯uenced by the presence of BM in the diet. There were signi®cantly greater speci®c activities of maltase (P < 0.01), leucine aminopeptidase (P < 0.05) and alkaline phosphatase (P < 0.001) in the jejunum as a result of supplementation with BM. Digestive enzyme activities in the ileum were unaffected. L-Tryptophan uptake by jejunal brush-border membrane vesicles was signi®cantly higher (P < 0.01) in chicks raised on the 5.0 g BM kg À1 diet than in the other chicks. The supplement led to minor improvement in body weight but no improvement in feed conversion ratio. These effects were related to changes in digestive enzyme activities and, perhaps, amino acid transport. INTRODUCTIONOligosaccharides occur naturally in many feed ingredients, the most common natural forms being the raf®nose series oligosaccharides. Raf®nose series oligosaccharides do not succumb to animal enzymes and tend to accumulate towards the posterior end of the gastrointestinal tract (GIT) where they are digested by microbial enzymes, to release gases that cause¯atulence in non-ruminant animals. 1,2 Previous research has therefore tended to attribute the poor growth of animals on legume seeds to the presence of oligosaccharides. This has been disputed by more recent research.
1. Pig intestinal sucrase and maltase activities increase markedly, and lactase activity decreases, during the second week of post‐natal life. Correlations noted between the time course describing these changes and that found previously to describe a decline in the ability of the pig intestine to take up macromolecules suggest that both events are subject to the same type of developmental control. 2. Injection of epidermal growth factor (EGF) into 3‐day‐old piglets increase sucrase and maltase activities measured 3 days later. These increases, which are not seen when measuring other hydrolase enzymes, are confined to the mid and distal regions of the small intestine. 3. Dexamethasone injected into 3‐day‐old piglets inhibits lactase and, on occasion, sucrase activities without affecting other intestinal hydrolases. Significant increases in sucrase and maltase activities also occur in distal intestine following injection of EGF plus dexamethasone into 3‐day‐old pigs. 4. Cytochemical analysis shows EGF effects on sucrase and maltase activities to be exerted in crypt and basal villus enterocytes produced post‐natally. Dexamethasone inhibits lactase activity mainly by acting on mid and upper villus enterocytes produced before birth. 5. EGF appears to increase sucrase and maltase activities by extending the time during which young enterocytes continue to accumulate these enzymes in their brush‐border membranes. Dexamethasone appears to cause a more fundamental change in the biochemistry of older enterocytes. accompanied by an increasing ability of these cells to transport neutral amino acids through a sodium‐dependent mechanism (see James, Smith, Tivey & Wilson, 1987a).
Background: Preoperative screening for coronavirus disease 2019 (COVID-19) aims to preserve surgical safety for both patients and surgical teams. This rapid review provides an evaluation of current evidence with input from clinical experts to produce guidance for screening for active COVID-19 in a low prevalence setting. Methods: An initial search of PubMed (until 6 May 2020) was combined with targeted searches of both PubMed and Google Scholar until 1 July 2020. Findings were streamlined for clinical relevance through the advice of an expert working group that included seven senior surgeons and a senior medical virologist. Results: Patient history should be examined for potential exposure to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Hyposmia and hypogeusia may present as early symptoms of COVID-19, and can potentially discriminate from other influenza-like illnesses. Reverse transcription-polymerase chain reaction is the gold standard diagnostic test to confirm SARS-CoV-2 infection, and although sensitivity can be improved with repeated testing, the decision to retest should incorporate clinical history and the local supply of diagnostic resources. At present, routine serological testing has little utility for diagnosing acute infection. To appropriately conduct preoperative testing, the temporal dynamics of SARS-CoV-2 must be considered. Relative to other thoracic imaging modalities, computed tomography has the greatest utility for characterizing pulmonary involvement in COVID-19 patients who have been diagnosed by reverse transcription-polymerase chain reaction. Conclusion: Through a rapid review of the literature and advice from a clinical expert working group, evidence-based recommendations have been produced for the preoperative screening of surgical patients with suspected COVID-19.
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