Laborationer har lång tradition i fysikundervisningen och det finns många klassiska skolexperiment. Samtidigt påverkas laborationsundervisningen av reformer och teknikutveckling. I denna studie fick lärare på tre gymnasieskolor diskutera sin laborationsundervisning. Analysen baseras på händelselogik, där handling ses som intentionell och styrs av determinanterna: målsättning, förmåga, plikt och mö

Lifetimes of some low-lying quartet levels in sulphur, chlorine and iron have been measured using the beam-foil technique. In general, the lifetimes obtained by curve fitting are in agreement with theory. However, the lifetime results for 3s3p(3P)3d 4P04D0 are somewhat higher than predicted, possibly due to the neglection of some of the cascades in the data analysis

The effect of adrenalectomy (Adx) on pancreatic lipase and colipase activities in normal, streptozotocin-induced diabetic, and obese Zucker rats was studied. It was found that Adx induced a rapid decrease in amylase activity, a rapid increase in lipase activity, and a slow increase in colipase activity in normal rats. Twenty days after Adx, the levels of amylase activity were 70% lower than contro

After insulin administration in vivo, changes in pancreatic lipase, colipase and amylase contents and outputs were assayed and quantitatively compared. The incorporation of [35S]cysteine into individual enzymes was measured. The mRNA coding for lipase and amylase were determined by dot-blot hybridization. It was found that insulin dose-dependently decreased lipase and colipase contents, but only s

Effects of short-term infusion and long-term injection of gastric inhibitory polypeptide (GIP) on changes in pancreatic lipase and colipase contents in rats were studied, and mRNAs encoding for lipase and colipase were determined by Northern blot hybridization with specific cDNA probes. GIP infused at a dose of 3 micrograms/h for 24 h significantly increased the pancreatic lipase content by 34% (P

The effects of endogenous and exogenous cyclic AMP on the synthesis of pancreatic lipase, colipase, and amylase were studied. Pancreatic lobules were prepared and incubated with forskolin, dibutyryl cyclic AMP (dbcAMP), and dibutyryl cyclic GMP (dbcGMP), respectively, in the presence of “S-cysteine”. The individual pancreatic enzymes were isolated by polyacrylamide gel electrophoresis, and the inc

The effects of emeriamine, a new anti-diabetic drug, on exocrine and endocrine pancreatic function in normal and diabetic rats have been studied both in vivo and in vitro. It was found that emeriamine dose-dependently normalized the symptoms of hyperingestion and hyperposia in streptozotocin (STZ)-induced diabetic rats, with fasting glucose levels significantly decreased and insulin levels not cha

The changes in contents of pancreatic carboxyl ester lipase, phospholipase A2, and lingual lipase in rats with streptozotocin (STZ)-induced diabetes have been studied. The contents of pancreatic carboxyl ester lipase and phospholipase A2 decreased by 40% and 45%, respectively, 5 days after injection of STZ, whereas pancreatic lipase steadily increased to 100% over control. The content of lingual l

The existence of a specific lysophospholipase in human pancreatic juice was evaluated. The proteins were separated by a series of chromatographic steps including Sephacryl S-200, cholate-Sepharose 4B, Sephadex G-100 and CM-Sephadex G-50. The enzyme activities against 1-palmitoyl lysolecithin (LL) as well as tributyrin (TB) and p-nitrophenyl butyrate (PNPB) were determined in all the fractions of t

Genistein, a tyrosine kinase inhibitor, inhibited cholecystokinin (CCK)-induced maximal amylase release from rat pancreatic acini by 18, 31, and 46% at concentrations of 100, 300, and 750 microM, respectively, after 30 min preincubation. Genistein similarly decreased amylase release stimulated by bombesin but not that stimulated by secretin or vasoactive intestinal peptide. The steps of stimulus-s

CCK rapidly converted Ca2+/calmodulin kinase II (CaMK II) to a Ca(2+)-independent form with peak action at 30 sec followed by decline to the basal level at 10 min. The threshold concentration of CCK for this action was 30 pM and maximum effect occurred at 1 nM, which induced a 6-10-fold increase. Bombesin and carbachol similarly induced CaMK II autonomous activity, whereas secretin and JMV 180 did

The existence and activation of mitogen-activated protein (MAP) kinase in isolated pancreatic acini have been demonstrated. Immunoblotting and immunoprecipitation revealed two forms of MAP kinase in pancreatic acini, with relative molecular masses of approximately 42 and 44 kDa. Both forms of MAP kinase were activated by cholecystokinin (CCK). The threshold concentration of CCK was approximately 3

Cholecystokinin (CCK) has recently been shown to activate mitogen-activated protein (MAP) kinase in rat pancreatic acini [Duan and Williams, Am. J. Physiol. 267 (Gastrointest. Liver Physiol. 30): G401-G408, 1994]. To evaluate the mechanism of MAP kinase activation, we studied the effects of CCK on MAP kinase kinase (MEK) in rat pancreatic acini. Two forms of MEK were identified by immunoblotting,

Previous studies indicated that there was an alkaline sphingomyelinase (SMase) activity in small intestine, but its properties have not been studied in detail. In the present work, we studied the distribution of this enzyme activity in rat gastrointestinal tract and characterized it in intestinal mucosal homogenates. Little alkaline SMase activity was detected in the stomach and the duodenum. The

Cholecystokinin (CCK) is known to rapidly and transiently increase both [Ca2+]iand autonomous CaM kinase II activity in rat pancreatic acini. Because induction of autonomous activity may involve intramolecular autophosphorylation, the effects of protein phosphatase inhibitors were examined. None of the inhibitors tested (okadaic acid, calyculin A, and cyclosporin A) affected basal activity. Okadai

The hydrolysis of sphingomyelin has been found to generate important signals regulating cell proliferation, differentiation and apoptosis. However, the enzymes responsible for digestion of dietary sphingomyelin have not been well documented. This study demonstrates the occurrence of a sphingomyelinase (SMase) in both human hepatic bile and gallbladder bile. The enzyme was equally found in both bac

Escherichia coli express fimbriae-associated adhesins through which they attach to mucosal cells and activate a cytokine response. The receptors for E. coli P fimbriae are the globoseries of glycosphingolipids; Gal alpha 1-->4Gal beta-containing oligosaccharides bound to ceramide in the outer leaflet of the lipid bilayer. The receptors for type 1 fimbriae are mannosylated glycoproteins rather than