In the past year, there have been many advances in the area of small bowel physiology and pathology. More than 1500 papers were assessed in preparation for this review. Some were selected and reviewed, with a particular focus on presenting clinically useful information for the practising gastroenterologist. Relevant review articles have been highlighted, and important clinical learning points have been stressed. The topics are varied in scope, and wherever possible show a logical progression from basic physiology to pathophysiology to clinical disorders and management.

In the past year there have been many advances in the area of small bowel physiology and pathology. In preparation for this review, over 500 papers were assessed; some have been selected and reviewed, with a particular focus on presenting clinically useful information for the practising gastroenterologist.

M ajor scientific advances have been made over the past few years in the areas of small bowel physiology, pathology, microbiology and clinical sciences. An in-depth review of the small bowel is presented. Topics discussed are enterocyte proliferation and growth factors; amino acids, peptides and allergies; motility; salt and water absorption and secretion -diarrhea; vitamins and minerals; early development and late ageing of the intestine; and ethanol. ENTEROCYTE PROLIFERATIONAND GROWTH FACTORS Small intestinal cell proliferation has been reviewed (1). The structural and functional integrity of the small intestine is maintained by the steady state of cell turnover whereby cell loss from the villi is balanced by cell production in the crypts. Each small intestinal crypt is composed of a single clone of cells, and several crypts contribute to each jejunal villus. The dynamic process of cell proliferation, migration and extrusion results in continuous renewal of the intestinal epithelia about every three days in rodents and every five days in humans. The majority of cells in both the crypt and villus compartments are enterocytes that acquire differentiated functions as they migrate out of the crypt. Migration of enterocytes from crypts to villi is coincident with the appearance of the differentiated phenotype. Little information is available on the molecular mechanisms that regulate cell lineage commitment, cell-specific gene expression or the process of differentiation as cells migrate from crypts to villi.Trefoil peptides are a group of small peptides that play a role in the process of maintaining the balance between proliferation and cell loss. The peptide is directed to the mucosal surface, in conjunction with mucin and glycoproteins. These trefoil peptides are resistant to protease digestion and ABR THOMSON, JA THOMSON, MJ ROPELESKI, GE WILD. Small bowel review: Part II. Can J Gastroenterol 1996;10(4): 261-273. Major scientific advances have been made over the past few years in the areas of small bowel physiology, pathology, microbiology and clinical sciences. Over 1000 papers have been reviewed and a selective number are considered here. Wherever possible, the clinical relevance of these advances have been identified. Topics discussed are enterocyte proliferation and growth factors; amino acids, peptides and allergies; motility; salt and water absorption and secretion -diarrhea; vitamins and minerals; early development and ageing of the intestine; and ethanol effects.

Significant advances have been made in the study of the small bowel. Part II of this two-part review of the small bowel examines the early development and later ageing of the small bowel; the effect of diabetes, alcohol, radiation and HIV on the small bowel; enteral and parenteral nutrition; the brush border membrane and enterocyte proliferation; and peptide hormones (including transforming growth factors, motilin peptide YY and cholecystokinin).

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