Mechanism of action of human pancreatic and salivary alpha-amylase on alpha-4-nitrophenyl maltoheptaoside substrate

We evaluated the enzymic mechanism by which alpha-4-nitrophenyl maltoheptaoside serves as a substrate for serum amylase (EC 3.2.1.1). Because polymeric substrates possess many potential sites of cleavage, the expression of enzymic activity as the number of micromoles of substrate transformed under defined conditions by an enzyme must be changed to "one microequivalent of group transformed." Therefore, we measured the activity of the isoenzymes of alpha-amylase with regard to suitable oligosaccharide substrates, which allowed us to express the catalytic activity in IUB units (U). By "high-performance" liquid chromatography we investigated the mechanism of human pancreatic and salivary alpha-amylase action, both alone and in combination with alpha-glucosidase (EC 3.2.1.20). On the basis of these results, we can describe exactly the entire reaction sequence and determine the stoichiometric coefficient of 4-nitrophenol within 0.02 mol/L (SD) produced under the assay conditions.

[A general view of the ambulatory care sector: Structural and functional study in the cantons of Vaud and Fribourg]

The project "Quantification and qualification of ambulatory health care", financed by the Swiss National Science Foundation and covering the Cantons of Vaud and Fribourg, has two main goals: --a structural study of the elements of the ambulatory care sector. This is done through inventories of the professions concerned (physicians, public health nurses, physiotherapists, pharmacists, medical laboratories), allowing to better characterize the "offer". This inventory work includes the collect and analysis of existing statistical data as well as surveys, by questionnaires sent (from September 1980) to the different professions and by interviews. --a functional study, inspired from the US National Ambulatory Medical Care Survey and from similar studies elsewhere, in order to investigate the modes of practice of various providers, with particular regard to interprofessional collaboration (through studying referrals from the ones to the others). The first months of the project have been used for a methodological research in this regard, centered on the use of systems analysis, and for the elaboration of adequate instruments.

[A structural study of the ambulatory care system using surveys of professions: methods and 1st results]

In Switzerland the ambulatory care system considered as a whole, is not sufficiently known, especially as regards number and location of institutions and professionals, forms of cooperation and measures of activity. The research team "Ambulatory care" of the Swiss National Research Programme No. 8 tries to fill that gap in the cantons of Fribourg and Vaud in pointing out to the recent but lasting numeric growth in all professions contributing to ambulatory care. The latter represent 42% of all health workers, and among them the physicians are 1/7. This study attracts attention to institutions and organizations like those providing home care and outpatient departments of regional hospitals.

Action pattern of human pancreatic alpha-amylase on maltoheptaose, a substrate for determining alpha-amylase in serum

An enzymatic assay for the determination of alpha-amylase in serum was developed which employed a soluble substrate, maltoheptaose, and a coupled enzymatic indicator reaction consisting of alpha-glucosidase and the hexokinase-glucose-6-phosphate dehydrogenase system. We used high-performance liquid chromatography (HPLC) to establish the action pattern of maltoheptaose under the test conditions: (A) the action pattern of alpha-amylase, (B) that of the combined action of alpha-amylase and alpha-glucosidase. Conductive to this effect was: the availability of pure maltoheptaose and human pancreatic alpha-amylase; the development of an adequate procedure for sample pretreatment (partition chromatography on a mixed-bed ion exchange) and of an HPLC system for separation of substrate and reaction products without interference from by products of the assay (partition chromatography on a cation-exchange column with acetonitrile-water); and the use of a new, very sensitive refractometric detector revealing sugar amounts as low as 40 ng. We derived the following stoichiometric equations: (see formula index).

Molar absorptivities of beta-NADH and beta-NAD at 260 nm

To determine the molar absorptivities of beta-NADH and beta-NAD at 260 nm, we purified the reduced form of the coenzyme by repeated anion-exchange chromatography. A NADH preparation was so obtained for which the 260 nm/340 nm absorbance ratio was 2.265. When calculated with epsilon 340 beta-NADH = 6.22 times 10-3 for beta-NADH at 260 nm and 25 degrees C, a molar absorptivity of 14.1 times 10-3 liter - mol minus 1 - cm minus 1 resulted from this quotient. By use of the lactate dehydrogenase or glycerol-3-phosphate dehydrogenase assay, respectively, and referring to the new absorption coefficient for NADH at 260 nm, the molar absorptivity of beta-NAD at 260 nm and 25 degrees C was established to be 17.4 times 10-3 liter - mol minus 1 - cm minus 1. The values observed are lower than those reported thus far.

Automation of multiple sephadex LH-20 column chromatography for the simultaneous separation of plasma corticosteroids

An automated method of Sephacex LH-20 chromatography has been developed for the simultaneous and complete separation of corticosterone, 11-deoxycortisol, aldosterone, cortisone and cortisol from a small plasma sample prior to radioimmunoassay. Using a controlled elution flow-rate of 40 ml/h and automated programme tape-controlled collection of the eluates from six columns eluted simultaneously, excellent reproducibility of elution patterns with minimal day-to-day and column-to-column variations could be achieved. The method can be easily extended and permits the reliable, rapid and easy routine separation of individual steroids from a single plasma or tissue extract on a multi-column scale.

Automated Determination of Serum Ceruloplasmin Activity with o-Dianisidine Dihydrochloride as Substrate

An automated method for the enzymatic determination of ceruloplasmin with o-dianisidine dihydrochioride as substrate is described. The method enables the measurement of 30 samples per hour with a coefficient of variation (day-to-day) of 2.8%. Results correlate well (r = 0.99) with those obtained by the corresponding manual method.