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J Bergsma

Publications and source records attributed to J Bergsma.

At least 37 records · Page 2Linked to original sources

Quality of life: does measurement help?

'Quality of life' is a very frequently applied concept nowadays. One may doubt whether everyone has the same connotation in mind while using this expression and why 'quality of life' attracts so much attention. Is the idea a very old one or is it a new and noble value? It is argued here that changes such as in the number of aged people and of chronically disabled people, combined with spectacular developments in medical technology and with a rise in knowledge and assertivity, created an increased awareness of 'quality of life' and its interaction with medicine. Moreover, limitations to budgets and technological developments trigger an interest in new arguments. 'Quality of life' plays an increasing role in all sorts of medical decisions, be it in policy decisions or in individual clinical decisions, be it formally assessed or implicitly weighted. A number of examples is briefly described to illustrate the very broad and diffuse use of quality of life as a criterion. Subsequently we have tried to operationalize the concept on 4 levels: macro, meso, personal and physical. The macro level applies to the meaning of life in a society; assessments of quality of life play a role, for instance, in discussions on euthanasia and in political decisions on medical investments. Examples of the meso level are the hospital, with its internal processes and its ties to the rest of the world, but also the patient in his social environment. On the personal level the individual's frames of reference on health, illness, future, pain and hope - both of the patient and the doctor - are being considered. It is argued that legitimation of important decisions, investments and interventions requires measurement of quality of life in an objective way and on different levels. Quantifying quality, however, appears hardly feasible. Therefore 'quality of life' is frequently measured at the fourth level only, the level of physical activities. Confining measurement to the measurable induces the question of whether it really is 'quality of life' that is being quantified. Still, results from such measurements can be of help in decision making. Who decides in clinical situations and in what way should 'quality of life' be involved in decision making? In one solution, perhaps the old fashioned one, the doctor takes all responsibility, possibly from a paternalistic ideal. Conversely, should the doctor behave in a completely non-directive way, full autonomy is given to the patient.(ABSTRACT TRUNCATED AT 400 WORDS)

Decision Making↗

The alpha-macroglobulins from rat plasma: structure, plasma clearance and endocytosis of complexes with subtilisin.

Rat alpha 2M was isolated from plasma of animals which had been treated with stress hormones. Polyacrylamide-gel electrophoresis of the reduced protein in the presence of sodium dodecyl sulfate showed a band with a Mr of 175,000. In a previous work (Biochem. J. 226, 75-84, 1985) we had found that rat alpha 1M consists of two types of subunits with Mr's of 163,000 and 37,000. Like the large subunit of alpha 1M the chain of alpha 2M contained a peptide bond that was susceptible to autolysis and a site that was split by trypsin. Negatively stained free alpha 2M could be distinguished from free alpha 1M under the electron microscope. Radioactively labelled alpha 2M was slowly cleared from plasma, but complexes of the protein with labelled subtilisin were rapidly cleared with first-order kinetics, showing a half-life of about 6 min. These complexes were mainly taken up by the liver, as had previously been described for alpha 1M-subtilisin complexes. Complexes of both macroglobulins competed with each other for uptake, indicating endocytosis via a common receptor.

Animals↗

Complexes of rat alpha 1-macroglobulin and subtilisin are endocytosed by parenchymal liver cells.

Rat alpha 1-macroglobulin was isolated from plasma. Gel electrophoresis of the denatured and reduced protein showed two bands, with Mr values of 163 000 and 37 000. The large subunit contained an autolytic site. This subunit was also split after reaction of the macroglobulin with trypsin. Electron microscopy showed that the macroglobulin changed towards a more compact conformation after reaction with this proteinase. Subtilisin, or alpha 1-macroglobulin, was labelled with a sucrose-containing radio-iodinated group that stays in lysosomes after endocytosis and breakdown of the tagged protein. After intravenous injection into rats, alpha 1-macroglobulin was cleared from plasma with first-order kinetics, showing a half-life of about 9 h, whereas complexes of alpha 1-macroglobulin and subtilisin were cleared with half-lives of only 3 min. Liver contained about 60% of the label at 30 min after injection of complexes. About 90% of the liver radioactivity was found in parenchymal cells isolated after perfusion of the liver with a collagenase solution. Subcellular fractionation indicated a lysosomal localization of the complexes. We conclude that endocytosis by parenchymal liver cells is the major cause of the rapid clearance of alpha 1-macroglobulin-proteinase complexes from plasma.

Animals↗

[Letter to nurses].

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Adaptation, Psychological↗

The properties of citrate transport in membrane vesicles from Bacillus subtilis.

The uptake system for citrate is induced in Bacillus subtilis W23 by growth in the presence of citrate and only membrane vesicles isolated from these cells show energy-dependent citrate uptake. Citrate transport in membrane vesicles is strictly dependent on the presence of divalent cations such as Mg2+, Mn2+, Zn2+, Ba2+, Be2+, Ca2+, Cu2+, Co2+ or Ni2+. The initial rate of citrate transport increases with the divalent cation concentration up to a maximum. The maximum initial rate of citrate uptake is reached with 2 mM Mg2+. The cations form stable chelates with citrate. The metal citrate complex is the transported solute. This is demonstrated for citrate uptake in the presence of Ca2+. Membrane vesicles from citrate-grown cells accumulate Ca2+ and citrate only if both solutes are present. Citrate and Ca2+ are accumulated in equimolar quantities. The uptake of Ca2+ but not of citrate is inhibited by Mg2+. Uptake of the metal-citrate complex is inhibited by the uncoupler carbonylcyanide p-trifluoromethoxyphenyl-hydrazone and in the presence of K+ ions by valinomycin and nigericin. The inhibitory effects correlate with the effects observed on the components of the proton-motive force, indicating that the proton-motive force is a driving force for metal-citrate transport. The number of protons (n) symported with the metal-citrate complex has been determined under different experimental conditions from the steady state levels of citrate accumulation, the electrical potential and pH gradient. This number varies from 1 at pH 4.7 to 2 at pH 8.0.

Bacillus subtilis↗

Purification and characterization of NADH dehydrogenase from Bacillus subtilis.

NADH dehydrogenase from Bacillus subtilis W23 has been isolated from membrane vesicles solubilized with 0.1% Triton X-100 by hydrophobic interaction chromatography on an octyl-Sepharose CL-4B column. A 70-fold purification is achieved. No other components could be detected with sodium dodecyl sulphate polyacrylamide gel electrophoresis. Ferguson plots of the purified protein indicated no anomalous binding of sodium dodecyl sulphate and an accurate molecular weight of 63 000 could be determined. From the amino acid composition a polarity of 43.8% was calculated indicating that the protein is not very hydrophobic. Optical absorption spectra and acid extraction of the enzyme chromophore followed by thin-layer chromatography showed that the enzyme contains 1 molecule FAD/molecule. The enzyme was found to be specific for NADH. NADPH is oxidized at a rate which is less than 6% of the rate of NADH oxidation. The activity of the enzyme as determined by NADH:3-(4'-5'-dimethyl-thiazol-2-yl)2,4-diphenyltetrazolium bromide oxidoreduction is optimal at 37 C and pH 7.5-8.0. The purified enzyme has a Kapp for NADH of 60 microM and a V of 23.5 mumol NADH/min X mg protein. These parameters are not influenced by phospholipids. The enzyme activity is hardly or not at all affected by NADH-related compounds such as ATP, ADP, AMP, adenosine, deoxyadenosine, adenine and nicotinic amide indicating the high binding specificity of the enzyme for NADH.

Bacillus subtilis↗