This study was undertaken to assess the usefulness of different techniques for determination of albumin excretion rate (AER). Ninety patients with type I (insulin-dependent) diabetes mellitus and 45 with type II (non-insulin-dependent) diabetes mellitus, with AER/24 h of less than 200 micrograms/min, were included. All patients were free of major systemic complications of diabetes and overt kidney disease (mean serum creatinine 1.1 +/- 0.1 mg/dl, range 0.4-1.2 mg/dl). We compared timed day, night, and 24-h specimens, as well as timed spot specimens during water-induced diuresis. Most patients with type I (75 of 90) and type II (30 of 45) diabetes had AER less than 20 micrograms/min and showed significant differences in AER that were dependent on the collection time. Differences were diminished or absent with AER less than 20 micrograms/min. Sensitivity, specificity, and prediction rates of AER in different specimens were evaluated against 24-h AER. Use of albumin concentrations and albumin-creatinine ratios did not improve test performance in comparison with AER. Sampling time and the overall rate of AER influenced measurement of urinary albumin excretion. Day or 24-h AER is most useful to determine the presence of abnormal AER. AER and albumin concentration in spot samples are of limited use for initial screening and frequently require day or 24-h specimens of AER for confirmation. Day or 24-h AER should be used for long-term follow-up of the diabetic patient.

SUMMARY The effect of aspirin on small intestinal function in six healthy volunteers was examined using a segmental perfusion technique, with a test solution of 40 mM D-glucose, 140 mM NaCl, and 0*5 % polyethylene glycol. Jejunal glucose, sodium, and water absorption rates were inhibited by 50 % after oral administration of 2-6 g aspirin. Adenosine triphosphate (ATP) concentration was assayed in jejunal mucosal biopsies before and after aspirin. There was an almost 50 %g decrease in mucosal ATP levels after aspirin. This effect may be mediated through cellular injury and impairment of mitochondrial energy metabolism. Received for publication 6 October 1976 homeostasis is influenced by the rate of intestinal glucose absorption, it may be asked whether salicylates affect glucose levels by impairing glucose transport. Although the effect of aspirin on gastric mucosal structure and function has been studied extensively, there is very little information regarding the effect of aspirin on small intestinal function. Aspirin is absorbed from the stomach, as well as from the mucosa of the upper small intestine. The rate of absorption depends on the amount of nonionised drug and its lipid solubility. Because of the low intragastric pH, aspirin is absorbed rapidly from the gastric mucosa in the nonionised form. However, an appreciable amount is also absorbed from the jejunum, since the intraluminal pH in proximal jejunum may be as low as 5 0-5 5, and approximately 10% aspirin would be still in a nonionised form, suitable for absorption (Woodbury, 1970). The large jejunal absorptive surface and the intestinal blood flow are also important factors which would influence aspirin absorption rates. Contact of aspirin with the brush border may have an effect on intestinal transport of nutrients predominantly absorbed from the jejunum.The purpose of this study was to examine the effect of a therapeutic dose of aspirin on jejunal absorption of glucose, sodium, and water. In addition, the effect of aspirin on ATP levels in jejunal biopsies was determined, since glucose and sodium transport depend on high energy compounds such as ATP. 187 on 11 May 2018 by guest. Protected by copyright.

The diagnostic value of 1-14C-lactose breath test was compared with the standard lactose tolerance test and lactase assay in jejunal biopsies in 16 control subjects, 14 patients with lactase deficiency (LD) proven by lactase assay and 20 patients with irritable bowel syndrome (IBS). 14CO2 specific activity in the 2-hr breath collection after administration of 1-14C-lactose (5 muCi) provided a satisfactory separation between the control and LD group. Values were 7.0 +/- 2.0% dose administered/mmoles 14CO2 X 10(-3) (mean +/- SD) in the control group versus 2.1 +/- 1.5 in LD (P less than 0.001) versus 4.9 +/- 2.3 in IBS (P less than 0.01). 1-14C-lactose breath test was superior to standard lactose tolerance test in specificity (P less than 0.05) and provided a satisfactory correlation between 14C-lactose absorption and lactase assay (r = 0.77). The prevalence of LD in IBS was 40% by the breath test and 35% by lactase assay, suggesting that lactose malabsorption may play a role in the symptoms in the population of some patients with IBS. It appears that 1-14C-lactose breath test is a sensitive, specific and accurate method for the diagnosis of LD in clinical practice and suitable for large scale epidemiological surveys.

Intestinal digestion of two tripeptides (leucyl-glycyl-glycine, prolyl-glycyl-glycine) and two disacchrarides (sucrose, maltose) was examined in the hamster by intestinal perfusion in vivo and hydrolysis of the substrates by microvillus membranes. Perfusion studies showed that luminal disappearance rates of leucyl-glycl-glycine were significantly higher than prolyl-glycyl-glycine (P less than o.001), sucrose (P less than 0.001), and maltose (P less than 0.005). Hydrolytic products of leucyl-glycyl-glycine, sucrose, and maltose were detected in the gut lumen in appreciable concentrations, whereas negligible concentrations of prolyl-glycyl-glycine products were present. Leucyl-glycyl-glycine hydrolysis in microvillus membranes was markedly higher than prolyl-glycyl-glycine (P less than 0.001), which was predominant in the cytoplasmic fraction. These results indicate that leucyl-glycyl-glycine, like sucrose and maltose, is hydrolyzed at the membrane. With some tripeptides, i.e., leucyl-glycyl-glycine, digestion occurs at the microvillus membrane with subsequent transport of hydrolytic products into the intestinal epithelial cell. Other tripeptides, i.e., prolyl-glycyl-glycine, may cross the membrane and undergo intracellular hydrolysis by cytoplasmic peptidases.

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