Adhesion of three Lactobacillus strains onto human epithelial intestinal Caco-2 and Int-407 cell lines was compared. More adhesion occurred onto Int-407. The trypsin and sodium periodate pretreatment of bacteria revealed different mechanisms of adhesion depending on the Caco-2 and Int-407, involving carbohydrates and proteins. The absence of adherence for one Lactobacillus strain onto both cell lines indicated the specificity of the adhesion. Electron microscopic observations showed that bacteria adhered by underlying the brush border microvilli of the Caco-2 surface contrasting onto the Int-407 which entrapped and surrounded them by fimbrial extracellular cell matrix material.
We have tested five Lactobacillus strains for their in vitro colonization ability in a human colon epithelium culture model. Positive colonization occurred in different degrees in the presence of four Lactobacillus strains. We have found that L. casei GG and L. acidophilus NCFB 1748 induce an intermediate colonization. These two strains, largely investigated by others, have been reported to be beneficial to humans. The use of human intestinal tissue in our study partially reconstitutes the complex architectural specificity of human epithelium with the mucus layer and more closely simulates the in vivo situation.
Growth hormone (GH) responses to sleep, insulin hypoglycaemia and arginine infusion. A few children with no apparent cause for their short stature, continue to grow poorly despite normal GH responses (>15mU/L) to pharmacological stimuli. It has been suggested that their GH secretion during sleep may more accurately reflect their true GH reserve. We have compared sleep related GH secretion (GH-Sleep) with GH responses to insulin hypoglycaemia (GH-I) and arginine infusion (GH-Arg.) in 19 children referred to our Growth Clinic. Blood was withdrawn continuously through an indwelling thromboresistant catheter (Cormed SL-65 Continuous Blood Withdrawal Pump) and divided into 15 minute aliquots, throughout approximately 5 hours of EEG monitored sleep. The following morning an, insulin hypoglycaemia/arginine infusion test was performed. GH was measured by radioiuununoassay. 2 patients had normal GH-Arg. responses but GH-Sleep peaks less than 15mU/~. Correlation coefficients, r, for peak serum GH levels were :for GH-I & GH-Sleep 0.55 (p<0.02), GH-Arg. & GH-Sleep 0.52 (p<0.02) and GH-I & GH-Arg. 0.56 (p <0.02). We conclude that sleep studies of GH reserve are indicated only when the results of stimulation tests are inconsistent with clinical findings.
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