1. Pig intestinal microvillus maltase/glucoamylase (EC 3.2.1.20) was solubilized from microvillus membranes using Triton X-I 00 and was purified by a specific anti-(maltase/glucoamylase) immunoadsorbent using elution with hypotonic solution. The specific activity was 20 -35 U x mg-' and the yield 13 %. The enzyme preparations were free of other known microvillus disaccharidases and peptidases (less than 0.4%) and showed one precipitate in crossed immunoelectrophoresis.2. The Triton-solubilized maltase/glucoamylase was amphiphilic as indicated by its detergent-binding properties. These properties were abolished by treatment with papain and was not registered for the enzyme released from the microvillus membranes by papain. The M , of the enzyme purified after solubilization by Triton X-100 and papain was 330000 and 210000, respectively, as determined by gel filtration. The M , difference indicates that small-molecular-weight peptide(s) binding a Triton X-100 micelle is (are) removed by proteolytic treatment.3. Maltase/glucoamylase isolated from pigs in which the pancreas had been completely disconnected from the duodenum three days before killing, migrated in polyacrylamide gel electrophoresis in dodecyl sulphate as one polypeptide chain ( M , . This was also the only band seen in some preparations obtained from ordinary pigs. However, in preparations from normal pigs, most frequently two additional bands ( M , 135 000 and M , 125000) with similar intensity to the larger band were seen. These two bands could be generated by treating preparations containing solely the larger band by pancreatic proteinases.4. Maltase/glucoamylase hydrolysis of maltose and starch had a broad pH optimum (pH 6-7). Using maltose as substrate the kinetics seemed to obey Michaelis-Menten kinetics (K, 3.74 mM). The enzyme effectively cleaves off glucose residues from the nonreducing end of glucose polymers containing a-(1 + 4) glucosidic bonds; cc-(1+6) bonds are also hydrolyzed but at a slow rate. The highest activities were observed for maltose and maltohexaose while the intermediate linear cc-(l+ 4) glucose polymers were hydrolyzed less effectively.Small intestinal maltase/glucoamylase (EC 3.2.1.20) is located in the microvillus membrane of the enterocytes [I, 21. The enzyme has earlier been purified as a papain-solubilized form from rat [3-61, rabbit [7] and human [8]. Papain solubilization probably releases the major, hydrophilic part of the enzyme carrying the activity, leaving the anchoring part in the membrane. Specificity studies on these enzyme preparations have revealed an a-glucosidase activity against glucose polymers of different size. The results on the structure of the papain-solubilized forms are difficult to interpret, as nicks may be introduced in the peptide chains during solubilization by the proteolysis.It has been demonstrated that maltase/glucoamylase can also be solubilized with the nonionic detergent Triton X-1 00 [9,10]. Detergent-solubilized maltase/glucoamylase was purified from rat intestine and some physica...

Information about genetic variation within the canine major histocompatibility complex (MHC) class II genes is limited. In common with most other vertebrate species the canine MHC, or DLA, includes genes which are homologous to human DR, DQ, and DP. Recently, at least one functional DLA DQ gene-pair has been characterized, but so far systematic screening efforts have been lacking. In the present study, we sequenced both cDNA and genomic clones derived from DLA DQ genes of Irish setter dogs. This breed was of interest, since it shows a high prevalence of gluten sensitive enteropathy (GSE), which may be a useful animal model for celiac disease (CD) of man. Interestingly, few of the alleles found in Irish setters were identical to those previously detected in other breeds. Three novel DLA DQA and four novel DLA DQB alleles were discovered in 19 unrelated dogs. Strong association between certain HLA DQ alleles and CD of man prompted us to screen the DQ alleles of members of a family of gluten-sensitive Irish setter dogs. No haplotypes or alleles were shared by all affected dogs, but one frequent haplotype in this family was also detected in an unrelated gluten-sensitive Irish setter; this haplotype was absent in the healthy dogs. This observation warrants further investigation by screening the DQ alleles of a large population of unrelated gluten-sensitive Irish setters.

Small intestinal bacterial overgrowth (SIBO) has been reported to occur commonly in dogs with signs of chronic intestinal disease. There are usually few intestinal histological changes, and it is uncertain to what extent bacteria cause mucosal damage. The aim of this study was to apply a differential sugar absorption test for intestinal permeability and function to the objective assessment of intestinal damage in dogs with SIBO. Studies were performed on 63 dogs with signs of chronic small and, or, large bowel disease, in which SIBO (greater than 10(5) total or greater than 10(4) anaerobic colony forming units/ml) was diagnosed by quantitative culture of duodenal juice obtained endoscopically. None of the dogs had evidence of intestinal pathogens, parasites, systemic disease or pancreatic insufficiency. differential sugar absorption was performed by determining the ratios of urinary recoveries of lactulose/rhamnose (L/R ratio, which reflects permeability) and D-xylose/3-O-methylglucose (X/G ratio, which reflects intestinal absorptive function) following oral administration. Dogs with SIBO comprised 28 different breeds, including 13 German shepherd dogs. SIBO was aerobic in 18/63 dogs (29 per cent), and anaerobic in 45/63 (71 per cent). Histological examination of duodenal biopsies showed no abnormalities in 75 per cent, and mild to moderate lymphocytic infiltrates in 25 per cent of the dogs. The L/R ratio was increased (greater than 0.12) in 52 per cent, and the X/G ratio reduced (less than 0.60) in 33 per cent of the dogs. Differential sugar absorption was repeated in 11 dogs after their four weeks of oral antibiotic therapy. The L/R ratio declined in all 11 dogs (mean +/- SD pre: 0.24 +/- 0.14; post: 0.16 +/- 0.11; P < 0.05), but changes in the X/G ratio were more variable. These findings show that SIBO is commonly associated with mucosal damage not detected on histological examination of intestinal biopsies, and that changes in intestinal permeability following oral antibiotics may be used to monitor response to treatment.

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