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Biomedical subjects

K Dabrowski

Publications and source records attributed to K Dabrowski.

36 records · Page 2Linked to original sources
PubMed1990

Gulonolactone oxidase is missing in teleost fish. The direct spectrophotometric assay.

Data in the literature imply that some fish species evolved with the capacity to synthesize ascorbic acid. Gulonolactone oxidase activity has been reported in kidney and/or liver tissues. However, it is shown here that this microsomal enzyme activity is missing in common carp hepatopancreas and kidney, whereas high activity was confirmed in pigeon kidney, rat liver, bovine liver and amphibian (Xenopus) kidney tissues. A new assay using either the whole tissue homogenate or microsomes solubilized by sodium deoxycholate was developed to directly measure the formation of ascorbic acid spectrophotometrically. Identical values were found using this assay as well as the assay in which formed ascorbate was determined by the dinitrophenyl hydrazine (DNPH) method. In some experiments, these results were confirmed by polarographically measured oxygen consumption.

Animals↗
PubMed1990

Influence of dietary magnesium on mineral, ascorbic acid and glutathione concentrations in tissues of a freshwater fish, the common carp.

Supplementation with dietary Mg at a minimum level of 0.06% seems to be essential to prevent the hypercalcinosis of the kidney and hepatopancreas in a fish, the common carp. Mg deficiency appears to have no effect on the Mg level in kidneys and hepatic tissue, whereas the Fe level in those tissues was significantly diminished by increasing dietary Mg supplementation up to 3.2 g.kg-1. Both hypercalcinosis and accumulation of Fe in soft tissues were more pronounced in fish offered diets high in protein (44%) compared to fish on low dietary protein (25%). The ascorbic acid in the hepatopancreas and kidney was greatly depleted in fish fed the high-protein diets, and this depletion did not correlate with the dietary Mg level nor with a high level of tissue Ca. However, the increased Ca concentration in the kidney coincided with the greatest depletion of ascorbate in fish fed a high-protein diet. The concentration of ascorbate in the brain was much less affected by a low level of vitamin C in the diets than in other tissues. Depletion of ascorbate in soft tissues did not correspond to fish growth but might be rather related to the metabolic rate imposed by the dietary nutrients. It is suggested that the Mg and ascorbic acid requirements in the carp are considerably elevated by the increased dietary protein level.

Animals↗
PubMed1989

Applications of a simultaneous assay of ascorbic acid, dehydroascorbic acid and ascorbic sulphate in biological materials.

A modified spectrophotometric assay for ascorbic acid and its derivatives based on their reaction with 2,4-dinitrophenylhydrazine (DNPH) is described. Using standard ascorbic acid or ascorbic sulphate solutions, together with animal tissue or compound diet extracts, the conditions for ascorbic acid degradation were determined. For the differential measurement of reduced ascorbic acid (AA), dehydroascorbic acid (dAA) and ascorbic sulphate (AS), five series of simultaneous determinations were performed. These included the use of (1) KBrO3 for the hydrolysis of AS, (2) 2,6-dichlorophenolindophenol as an oxidant, (3) DNPH to form a hydrazone derivative with dAA and (4 and 5) two blanks (where ascorbate was degraded) to correct for interfering substances. A variety of vertebrate and invertebrate tissues were examined for their ascorbate content, and the advantages of the modified procedure over currently available assays are discussed. The results suggest that the Artemia cyst is a unique material in which ascorbic sulphate is present in large amounts whereas fish tissues do not contain this form of vitamin C.

Animals↗
PubMed1989

The effect of ascorbate on proteolytic enzyme activities in fish.

In vitro studies showed that an ascorbic acid concentration of 15 mM depressed the trypsin activity in three fish species by 50%, whereas dehydroascorbic acid and ascorbic sulfate did not inhibit trypsin or chymotrypsin activities. However, this inhibitory action is unlikely in vivo because ascorbic acid is rapidly oxidized in the digestive tract content to the dehydroascorbic acid.

Animals↗
PubMed1988

Absorption of intact proteins by the intestinal epithelium of trout, Salmo gairdneri. A luminescence enzyme immunoassay and cytochemical study.

In the rainbow trout, a carnivorous species with a stomach, orally administered horseradish peroxidase (HRP) crossed the intestinal epithelium into the circulation. The protein first appeared in the blood 7 to 8 h after intubation, and could be assayed up to 24 h after administration. The method used, which combines ELISA (enzyme-linked immunoabsorbant assay) and chemiluminescence, enabled the transfer to be measured quantitatively. There was a direct correlation between the quantity ingested and the quantity transferred to the plasma within the experimental limits chosen. The clearance was monophasic and exponential (clearance rate: 3% per minute). Up to 6% of the ingested HRP was transferred to the blood. By cytochemistry it was possible to demonstrate that the protein crossed the intestinal cells at the level of the posterior segment, escaping the particularly intense intracellular lysosomal digestion. After entering the intercellular space, HRP was transferred to the interstitial space of the subepithelial lamina propria. During this transfer the HRP was in close contact with infiltrated macrophages and leukocytes resembling lymphoid cells. Thus, the passage of these protein particles could be the first indispensable step in the possible triggering of a local and/or a systemic immune response.

Animals↗
PubMed1986

Protein digestion and amino acid absorption along the intestine of the common carp (Cyprinus carpio L.), a stomachless fish: an in vivo study.

Protein hydrolysis to peptides and free amino acids and the apparent absorption of amino acids (AAaa) were evaluated in different segments of carp intestine. The AAaa analysed using Cr2O3 as a marker indicated that 73.2% of the amino acids were absorbed in the first 20% of the intestinal tract and 5.3 and 21.5, respectively, in the following segments (20% of gut length). Except for methionine and histidine, essential free amino acid concentration decreased significantly along the intestine. Of the nonessential amino acids, glutamate and aspartate concentrations increased in the hind gut. The absolute amount of the peptide amino acid fraction decreased towards the middle intestine but, expressed as a proportion of the total amino acid content, it changed little along the intestine: 49 and 54% in the anterior and posterior intestine, respectively. The molar concentration of the peptide amino acid fraction was much higher in carp intestine (543.9 mM) than in rainbow trout (147.3 mM) or human (143.9 mM) intestine.

Amino Acids↗
PubMed1983

Comparative aspects of protein digestion and amino acid absorption in fish and other animals.

1. Molar concentrations of amino acids in the content of subsequent parts of alimentary tract of rainbow trout and common carp have been calculated. 2. The ratio of free amino acid concentration in intestinal content to blood of carp most commonly was between 10 and 20 and decreased as digestion proceeded. 3. Free amino acid concentration in gut content of fish appeared several times higher than that in reptiles or mammals. 4. Absorption rate of amino acids in carp was most intense during the first 3 hr after feeding and generally similar to that found in caymans. 5. Release rate of amino acids from dietary protein was most intense in the second segment of carp intestine where most of amino acids were also absorbed. 6. Requirements of essential amino acids based on their absorption rate were determined.

Amino Acids↗
PubMed1983

Postprandial metabolic changes in larval and juvenile carp (Cyprinus carpio).

Ammonia-nitrogen excretion and oxygen consumption rates after a meal were followed in carp larvae and juveniles of different sizes, starting from early exogenous feeding and until they had reached about 1 g of body weight. There was an immediate rise in the nitrogen excretion rate after feeding; the amplitude and duration of this increase were affected by body weight (BW) and the amount of nitrogen consumed (NI) and could be described by the equation: 37.61 BW-0.311 NI0.802. Endogenous nitrogen excretion rate and basal metabolic rate were affected by both nutritional status and previous nutritional history. A model used to describe the postprandial nitrogen excretion pattern in young carp fitted well with the experimental data. The different coefficients of the model were affected by body weight.

Ammonia↗
PubMed1982

Postprandial level of free amino acids in fish brain.

1. Free amino acids were examined in common carp (Cyprinus carpio L.) brain 3, 6, 24 and 72 hr after a meal. 2. In common carp brain glutamic acid (409.6 +/- 37.6 mg/100 g dry matter), threonine (232.8 +/- 24.6) and histidine (191.3 +/- 70.1) were the most abundant free amino acids. 3. The ratios between the brain and the whole blood concentrations (B/W) expressed as the amounts of moles per tissue water were examined. 4. Glutamic acid, histidine, threonine, alanine, methionine, serine and glycine were found in consistently higher concentration in fish brain than in blood.

Amino Acids↗
PubMed1978

The density and chemical composition of fish muscle.

The relationship between the density of muscle from Coregonus pollan Thompson and its chemical composition has a parabolic nature which makes prediction of fat or dry matter content from density impossible.

Adipose Tissue↗