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Biomedical subjects

C Hansson

Publications and source records attributed to C Hansson.

At least 91 records · Page 5Linked to original sources
PubMed1985

Production of 6-hydroxydopa by human tyrosinase.

A tyrosinase obtained from cultured human melanoma cells was found to oxygenate 2,4-dihydroxyphenylalanine to the strongly cytotoxic amino acid 6-hydroxydopa (2,4,5-trihydroxyphenylalanine). The oxygenation was dependent on the presence of a reducing co-substrate such as dopa or dopamine. The rate of oxygenation of 2,4-dihydroxyphenyl-D,L-alanine was similar to that of L-tyrosine, the normal substrate of tyrosinase. The enzymatic reaction demonstrated may prove of value in the chemotherapy of human melanoma.

Catalysis↗
PubMed1985

Melanocyte metabolites in the urine of people of different skin colour.

The urinary excretion of 2 melanocyte metabolites was studied in normal people of different skin type. The sulphur-free indole derivative 6-hydroxy-5-methoxyindole-2-carboxylic acid was excreted in larger quantities by people with genetically dark skin, whereas the excretion of 5-S-cysteinyldopa was not related to pigment type. No correlation between 5-S-cysteinyldopa and 6-hydroxy-5-methoxyindole-2-carboxylic acid excretion emerged.

Adult↗
PubMed1985

Candida albicans infections in leg ulcers and surrounding skin after the use of ointment impregnated stockings.

Six elderly women treated with double elastic bandages for chronic venous leg ulcers presented a clinical picture beneath these bandages as seen in intertriginous candidiasis. Painful, bright red, glistening skin lesions with pustules, denuded skin and scales were seen. Cultures on Sabouraud's agar from skin erosions and toe webs confirmed the suspicion of Candida albicans infection. Treatment with topically applied clotrimazole cream resulted in relief of pain and healing of skin lesions. There is a possibility of the Candida albicans having been transmitted from the toe webs by the bandages, and that the bandages creates a microenvironment suitable for growth of the yeast.

Aged↗
PubMed1985

Oxidation of dopa in human albinism.

The urine of an albino woman contained small quantities of 5-S-cysteinyldopa; 6-hydroxy-5-methoxyindole-2-carboxylic acid, a melanin precursor metabolite, was lacking. The 5-S-cysteinyldopa excretion observed may reflect non-specific oxidation of dopa. Two other albino patients showed normal values for the excretion of 5-S-cysteinyldopa and of 6-hydroxy-5-methoxyindole-2-carboxylic acid.

Adult↗
PubMed1985

Urinary excretion of 5-S-cysteinyldopa and 6-hydroxy-5-methoxyindole-2-carboxylic acid: differences between pigmented and albino mice.

Urinary excretion of the phaeomelanin precursor 5-S-cysteinyldopa (5-S-CD) and the eumelanin metabolite 6-hydroxy-5-methoxyindole-2-carboxylic acid (6H5MI-2-C) was studied in black and albino mice. The urinary concentration of 5-S-CD was 31.7 ng/ml in black and 16.1 ng/ml in albino mice. The concentration of 6H5MI-2-C was 21.0 ng/ml in the urine of black mice. The compound could not be demonstrated in the urine of albino mice.

Albinism↗
PubMed1985

Urinary excretion of melanocytic metabolites in fertile women.

Pregnant women and women taking oral contraceptives show urinary excretion values of 5-S-cysteinyldopa and of 6-hydroxy-5-methoxyindole-2-carboxylic acid in the same range as nonpregnant women not taking oral contraceptives. The excretion of these melanoma markers can therefore be used in in the biochemical diagnosis of metastatic melanoma in pregnancy and in women taking oral contraceptives.

Adult↗
PubMed1984

Reaction of histamine with o-phthalaldehyde: isolation and analysis of the fluorophore.

Histamine reacts with o-phthalaldehyde (OPT) to form colored as well as highly fluorescent derivatives. After large-scale synthesis, the chromophores were eliminated and the pale yellowish fluorophore was isolated by a series of chromatographic steps, followed by semipreparative high-performance liquid chromatography. Structural analysis of the fluorophore was performed using NMR and mass spectrometry. The isolated fluorophore was found to be a condensation product of 2 molecules of OPT and 1 molecule of histamine, arranged to form a complex dihydrophenantroline derivative with a quaternary amine group. The molecular weight of its chloride salt was 379.5. It was shown that the fluorophore exists in aqueous milieu as an equilibrium between three isomers.

Aldehydes↗
PubMed1984

High-performance liquid chromatographic determination of histamine in biological samples after derivation with o-phthalaldehyde.

A high-performance liquid chromatographic (HPLC) method for the determination of histamine in tissues, based on precolumn derivation with o-phthalaldehyde, is described. Trichloroacetic acid extracts of rat brain, but not of rat stomach or of rat peritoneal mast cells, had to be cleaned-up by a chromatographic step before HPLC. The extracts were allowed to react with o-phthalaldehyde at pH 12.5 and -20 degrees C for 12 h, followed by acidification to pH 2.0. HPLC was performed on a reverse-phase column with isocratic elution using sulfuric acid in methanol as solvent system. A fluorescence detection system was used; excitation was set at 353 nm and emission was read at 451 nm. One chromatographic run was completed in 20 min. The detection limit with the conventional procedure was 1.5 ng histamine per sample, with a scaled-down procedure it was 250 pg per sample. With extracts of rat gastric mucosa the within-run variation was 2.7% and the day-to-day variation 4.5%.

Aldehydes↗
PubMed1984

6-Hydroxy-5-methoxyindole-2-carboxylic acid in normal human urine.

The presence of 6-hydroxy-5-methoxyindole-2-carboxylic acid (6H5MI-2-C) in normal human urine was demonstrated by mass spectrometry. A quantitative method based on HPLC with fluorometric detection was developed for the determination of 6H5MI-2-C. In normal subjects the mean urinary concentration of 6H5MI-2-C was 38 mumol/mol of creatinine (range 6-76 mumol/mol).

Gas Chromatography-Mass Spectrometry↗
PubMed1984

Leg and foot ulcers. An epidemiological survey.

Medical records for leg and foot ulcer patients have been investigated, 1377 patients were found. The median age for women was 76 years and for men 70 years. Totally there was a majority of women, 61%. The age specific frequencies for leg and foot ulcer patients did however not differ between men and women. Thirty percent of all patients had ulcers on the feet only. The ratio between men and women for feet ulcers was 1:1. Men got their feet ulcers 5-10 years earlier than women. Seventeen percent of all patients had ulcers on the medial side of the calf only. Seventy percent of these patients were women. A rough estimate of the prevalence of leg and foot ulcer patients was made to between 0.2-0.4% of the whole population. The involvement of different medical disciplines in the care of leg and foot ulcer patients in Gothenburg is reported.

Adult↗
PubMed1983

Preparative affinity electrophoresis: application to human erythrocyte carbonic anhydrase.

A modification of affinity electrophoresis for preparative purposes is described. This method has been applied to the purification of human erythrocyte carbonic anhydrases B and C. During conventional affinity chromatography some hemoglobin contamination occurs. By introduction of an electrophoretic purification step after the immobilization of carbonic anhydrase to the affinity gel, the hemoglobin impurity is reduced about eight and two times in the preparations of the B and C enzymes, respectively, compared to the enzymes purified by affinity chromatography.

Carbonic Anhydrases↗
PubMed1983

A quantitative method for determination of 5,6-dihydroxyindole-2-carboxylic acid using high-pressure liquid chromatography with fluorometric detection.

A method for the determination of the urinary melanocyte metabolite 5,6-dihydroxyindole-2-carboxylic acid is described. The catecholic indole is adsorbed onto alumina, chromatographed on a reverse-phase octadecyl silica column, and detected by fluorometry. The sensitivity of the method permits detection of 1 pmol injected.

Chromatography, High Pressure Liquid↗
PubMed1983

Methaemoglobin-catalysed formation of dopa and 6-OH-dopa from tyrosine.

An extract of bovine retina and choroid with tyrosine hydroxylating and dopa-oxidizing capacity also showed marked formation of 6-OH-dopa on incubation with tyrosine and ascorbic acid. The extract contained appreciable amounts of methaemoglobin as determined spectrophotometrically, and boiled extracts also showed catalytic activity. The effect of methaemoglobin on the oxidation of tyrosine and dopa was therefore investigated. Methaemoglobin catalysed the formation of dopa and 6-OH-dopa in the presence of tyrosine and ascorbic acid. Hydrogen peroxide plays an important role in this reaction: the rates of formation of both dopa and 6-OH-dopa were increased by addition of hydrogen peroxide but diminished by addition of catalase. Methaemoglobin also catalysed the formation of cysteinyldopa from dopa and cysteine.

Animals↗
PubMed1982

The effect of cysteine on oxidation of tyrosine, dopa, and cysteinyldopas.

The influence of cysteine on the oxidation of tyrosine, dopa, and monocysteinyldopas by mushroom tyrosinase was reexamined. During oxidation of tyrosine in the presence of cysteine the concentration of dopa increased slowly, whereas the concentration of cysteinyldopas increased more rapidly. When the concentration of cysteine decreased the cysteinyldopas were rapidly consumed and dopa concentrations increased sharply. Experiments on the oxidation of dopa by tyrosinase in the presence of cysteine showed that this thiol does not inhibit the oxidation. Dopa concentrations decreased more rapidly in the presence of cysteine because cysteine addition to dopaquinone prevented reformation of dopa from dopaquinone. Both 2-S-cysteinyldopa and 5-S-cysteinyldopa are substrates for tyrosinase. The oxidation of cysteinyldopas was inhibited at high cysteine concentrations. The greater part of 2,5-S,S-dicysteinyldopa formed during the oxidation of monocysteinyldopas in the presence of cysteine is derived from 5-S-cysteinyldopa, which is a better substrate for tyrosinase than 2-S-cysteinyldopa. The fact that cysteine binds more rapidly to 5-S-cysteinyldopaquinone than to 2-S-cysteinyldopaquinone further stresses the importance of 5-S-cysteinyldopa in the formation of 2,5-S,S-dicysteinyldopa. Oxidation of dopa in the presence of cysteine and glutathione or methionine showed that glutathione is added to dopaquinone but less rapidly than cysteine. Methionine showed insignificant addition to dopaquinone. When dopa or 5-OH-dopa is added to an incubate of cysteinyldopa and tyrosinase the oxidation of cysteinyldopa is accelerated owing to oxidation of cysteinyldopa by dopaquinone or 5-OH-dopaquinone.

Ascorbic Acid↗