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Biomedical subjects

R Tenhunen

Publications and source records attributed to R Tenhunen.

At least 73 records · Page 4Linked to original sources
PubMed1981

Purification and characterization of an acid glutathione S-transferase from human lung.

An acid glutathione S-transferase (EC: 2.5.1.18) from human lung was purified and characterized. The purification procedure included two isoelectric focusing runs, Sephadex G-100 gel filtration, glutathione-affinity chromatography, and Sephadex G-75 gel filtration. With respect to the properties studied the acid lung transferase differed from human liver transferases alpha-epsilon, but it bore a close resemblance to the other human low pI transferases. Bilirubin affected the kinetics of the lung enzyme markedly differently as compared with transferase p, suggesting possible nonidentity between these enzymes. The acid lung transferase represented about 97% of the total glutathione transferase activity of the lung 100,000 g supernatant used in this work.

Chromatography, Affinity↗
PubMed1980

Biochemical effects of carbon monoxide poisoning in rat brain with special reference to blood carboxyhemoglobin and cerebral cytochrome oxidase activity.

Male Wistar rats exposed to 1000 ppm carbon monoxide for 3 h showed a rapid removal of carbon monoxide from the blood, and a cerebral cytochrome oxidase activity within the control range immediately after the end of the exposure. The cytochrome oxidase activity decreased while carboxyhemoglobin concentration diminished during the reoxygenation period. The effect might have been caused through a loss of mitochondria by increased lipid peroxidation as cerebral glutathione concentration decreased and lysosomal acid proteinase activity increased in glial cell fractions. The present results seem to indicate that the cerebral cytochrome oxidase may not be specifically inhibited in non-lethal carbon monoxide poisoning despite its proven interactions in vitro.

Animals↗
PubMed1980

Serum immunoreactive trypsin and trypsin inhibitors during acute pancreatitis.

Serum trypsin, total trypsin-inhibitor capacity, alpha-1-antitrypsin and alpha-2-macroglobulin were analyzed daily in ten patients hospitalized as a result of acute pancreatitis. Markedly raised serum trypsin concentrations were found in all patients. Alpha-1-antitrypsin and the trypsin-inhibitor capacity were also significantly increased as compared to post-illness values, but alpha-2-macroglobulin tended to decrease during acute pancreatitis. The post-illness values of all these parameters were in the normal range. It is concluded that a deficiency of alpha-1-antitrypsin, trypsin-inhibitor capacity of alpha-2-macroglobulin is not present in patients with acute pancreatitis which could render the pancreas more vulnerable to its own proteases. During acute pancreatitis trypsin is released into the circulation, but it is effectively inactivated by serum protease inhibitors, mainly alpha-1-antitrypsin, which can be seen as an increased trypsin-inhibitor capacity in these patients. The use of protease inhibitors in the treatment of acute pancreatitis seems to be unnecessary against this background. Increased serum trypsin values can be used when confirming the diagnosis of acute pancreatitis.

Acute Disease↗
PubMed1980

New method for liquid-chromatographic measurement of erythrocyte protoporphyrin and coproporphyrin.

We describe a "high-pressure" liquid-chromatographic method for separating all the porphyrins in the heme biosynthetic pathway. The preliminary extraction and purification method is such that only erythrocyte porphyrins with fewer than five carboxyl groups, which includes protoporphyrin and the much smaller amount of coproporphyrin present, are measured. The porphyrins extracted from erythrocytes are chromatographically separated by use of a simple eluent system and fluorometrically detected.

Adult↗
PubMed1979

An intestinal receptor for heme.

Porcine upper small intestine took up radioactive heme in vitro. The binder was localised to the brush borders, was solubilized with Triton X-100 and bound heme with high affinity. The binding was inhibited with non-radioactive heme but not with FeSO4, and control experiments indicated that it was not any of the known heme binders or aggregated heme. The binding factor could also be solubilized from human duodenum.

Animals↗
PubMed1978

Cerebrospinal fluid beta 2-microglobulin in neurological disorders.

Beta-2-microglobulin was measured in specimens of cerebrospinal fluid (CSF) collected from 167 patients classified in 14 diagnostic categories at an outpatient Department of Neurology. In the control group of 29 subjects without any obvious disease of the nervous system, the concentration of beta-2-microglobulin was 1.15 +/- 0.37 mg/1 (M +/- s.d.). The concentration was almost significantly elevated in the groups with fresh brain infarct, central nervous system infection, and polyneuropathy. The serum concentrations of beta-2-microglobulin did not differ significantly among these diagnostic categories. The mean ratio between CSF and serum beta-2-microglobulin was 0.79 +/- 0.32 in the control group and more than 1.0 in the patients with brain infarcts, CNS infections and spinal paresis, but the differences were not statistically significant.

Adolescent↗
PubMed1977

Heme catabolism in human kidneys. Effect of various nephritides.

The role of the kidneys in heme metabolism was examined by determining heme oxygenase and biliverdin reductase activities in needle biopsy specimens from the kidneys of 11 female and 14 male patients with different renal diseases. The results show that both enzymes are present in human renal tissue. Our results indicate that heme oxygenase and biliverdin reductase increase slightly with age, but that there is no sex difference. A rising serum creatinine concentration is not reflected in the activity of heme degrading enzymes. Neither do the different types of nephritides, without detectable hemolysis, show significant differences in the renal activities of heme oxygenase and biliverdin reductase. This study thus outlines the basal physiological role of the human kidneys in heme degradation.

Adolescent↗
PubMed1976

Low serum bilirubin in chronic renal failure. Relation to haem metabolism.

In renal failure serum bilirubin values are lower than normal. When renal failure is moderate this decrease is not due to a reduced-red-cell mass or to low levels of serum albumin. In splenic fine-needle aspirates from patients with renal failure, conditions for haem degradation were normal as indicated by normal activities of haem oxygenase and biliverdin reductase. Nor were the in vitro activities of these enzymes significantly depressed in the presence of ultrafiltrates of uraemic sera or of high concentrations of creatinine, urea or methylguanidine. The capacity of plasma from patients with renal failure to bind bilirubin was less than that of normal plasma, which at least partially explains the observed low values of serum bilirubin. There remains the possibility that in renal failure some bilirubin is removed from the plasma by a hitherto unknown route.

Bilirubin↗
PubMed1976

The enzymatic conversion of heme to bilirubin in vivo.

The conversion of hemoglobin to bilirubin IXalpha in vivo probably proceeds via alpha-hydroxyheme to carbon monoxide and biliverdin-iron complex; after hydrolysis, biliverdin IXalpha is liberated from the iron complex and reduced enzymatically to bilirubin IXalpha. For these reactions molecular oxygen, NADPH and a functioning microsomal electron transport system are needed to generate a reaction radical to transform the heme at the alpha-bridge to alpha-hydroxyheme. After that the reaction proceeds spontaneously. During this reaction sequence heme is readily bound to an insoluble and substrate-inducible protein, which behaves as a stereospecific oxidase. The crucial point in all likelihood is the nature of this heme-binding protein. It seems to be a large protein molecule having a molecular weight in excess of 200,000 and located within the membrane of the endoplasmic reticulum. The conversion of heme to bilirubin has thus some characteristics of nonenzymatic coupled oxidation and, on the other hand, of mixed-function oxidations catalyzed by cytochrome P-450. The exact nature and the regulation of this process, however, appears to be quite different from that manifested with drugs and steroids.

Animals↗
PubMed1976

Bone marrow: its contribution to heme catabolism.

Heme oxygenase (HO) and biliverdin reductase (BR), the two NADPH-dependent enzymes involved in the degradation of hemoglobin and its derivatives, were measured in bone marrow aspirates from 5 hematologically normal persons, 4 patients with chronic leucemia (CL), 11 patients with acute leucemia (AL), 8 patients with refractory sideroblastic anemia (RA), 7 patients with iron-deficiency anemia (IA), 5 patients with hemolytic anemia (HA), and 7 patients with secondary anemia (SA) to determine the enzymatic capacity of the bone marrow in different hematologic disorders for heme catabolism. HO activity in the bone marrow of normal persons was 0.42 +/- 0.28 (SD) nmoles bilirubin/10 mg protein/min; in CL, 2.15 +/- 1.34; in AL, 0.39 +/- 0.25; in RA, 0.58 +/- 0.37; in IA, 0.41 +/- 0.28; in HA, 2.56 +/- 1.40; and in SA, 1.72 +/- 1.06. BR activity, respectively, was in normal persons 8.7 +/- 2.4 (SD) nmoles bilirubin/10 mg protein/min; in CL, 13.6 +/- 9.1; in AL, 3.8 +/- 3.1 in RA, 5.1 +/- 2.7; in IA, 5.5 +/- 3.7; in HA, 17.0 +/- 7.2; and in SA, 10.5 +/- 4.2. On the basis of these findings it seems evident that both oxygenase and biliverdin reductase activities of the bone marrow are capable of adaptive regulation. The physiologic role of bone marrow in heme catabolism seems to be of significant importance.

Anemia↗