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Biomedical subjects

R Tenhunen

Publications and source records attributed to R Tenhunen.

At least 55 records · Page 3Linked to original sources
PubMed1985

Variant of acute intermittent porphyria with normal erythrocyte uroporphyrinogen-I-synthase activity.

A kindred in which several members have otherwise typical acute intermittent porphyria but normal erythrocyte uroporphyrinogen-I-synthase activity has been described from Finland. We studied two porphyric members of this kindred, two patients with typical acute intermittent porphyria, and two healthy controls using the delta-aminolaevulinic acid loading test and by measuring the erythrocyte enzymes of haem biosynthesis. The excretion pattern of haem precursors after the delta-aminolaevulinic loading test in the members of the kindred studied, was similar to that in typical acute intermittent porphyria suggesting an identical enzyme defect in the liver. The activity of all red cell enzymes studied was normal in the members of the kindred. The results suggest that porphyria in the kindred studied is a variant of acute intermittent porphyria, where the uroporphyrinogen-I-synthase defect is manifested in the liver but not in red cells.

Acute Disease↗
PubMed1985

Coproporphyrinogen oxidase activity and porphyrin concentrations in peripheral red blood cells in hereditary sideroblastic anaemia.

The activity of coproporphyrinogen oxidase and the concentrations of coproporphyrin and protoporphyrin (measured by HPLC) in peripheral red blood cells were established in 2 families with different types of hereditary sideroblastic anaemia. 2 males and 4 females were members of a family with an X-chromosome-linked and pyridoxine-responsive HSA, and 3 females were members of another family where the mode of inheritance is not clear and where pyridoxine did not produce a haematological response. Coproporphyrinogen oxidase activity was normal in 8 of 9 patients and slightly decreased only in 1 patient. All patients had normal red cell coproporphyrin concentrations, but red cell protoporphyrin concentration was decreased in 4 patients. These findings indicate that in vivo haem synthesis was not impaired at the step of coproporphyrinogen oxidase, hence enzymatic defects in earlier steps of haem synthesis are more evident. Earlier suggestions of impaired haem synthesis at this level, based on observed increased concentrations of coproporphyrin in peripheral red blood cells might be explained by the use of unspecific methods.

Adolescent↗
PubMed1985

Reversal of sulfide-induced effects on porphyrin metabolism by exogenous heme.

Rats injected intraperitoneally with 0.15 mmol sodium sulfide/kg body weight showed decreased reticulocyte delta-aminolevulinic acid synthase and heme synthase activities 24 h later. Liver delta-aminolevulinic acid synthase and heme oxygenase activities were also decreased at the same time. Injection of heme arginate (10 mg heme/kg body weight) intraperitoneally 3 h after the sulfide dose completely corrected the sulfide effects and greatly stimulated the hepatic heme oxygenase activity.

5-Aminolevulinate Synthetase↗
PubMed1984

Hemoglobin-degrading enzymes in experimental subcutaneous hematomas.

The activities of heme oxygenase and biliverdin reductase were determined in subcutaneous (s.c.) hematomas of rats after different periods of vital time. The postmortem stabilities of the heme-degrading enzymes were also studied by keeping the rats with vital hematomas for 1-5 days at temperatures of +4 degrees C and +22 degrees C. A tenfold increase of heme oxygenase activity over the starting level was observed in 2-9-day-old vital hematomas, when the specimens were taken immediately after death. Biliverdin reductase showed only negligible changes. Postmortally, heme oxygenase activity started to decrease in hematomas immediately at +22 degrees C and from day 2 on at +4 degrees C.

Animals↗
PubMed1984

Trinitrotoluene-induced effects on rat heme metabolism.

A single injection (100 mg/kg body wt) of trinitrotoluene in rats caused decreased delta-aminolevulinic acid synthase activity in reticulocytes and decreased erythrocyte coproporphyrin concentration 48 hr after the intraperitoneal dosage. For comparison, liver delta-aminolevulinic acid synthase was unaffected while heme synthase activity was below the control range at the same time. Heme oxygenase activity increased simultaneously. These effects are likely to lead to a negative heme balance and may be developed for a biological exposure test to trinitrotoluene in occupational health service.

5-Aminolevulinate Synthetase↗
PubMed1983

Changes in haem synthesis associated with occupational exposure to organic and inorganic sulphides.

1. Analysis of reticulocytes for delta-amino-laevulinic acid synthase (AmLev synthase, EC 2.3.1.37) and haem synthase (EC 4.99.1.1) activity in 17 workers in pulp production with low-level hydrogen sulphide and methylmercaptan exposure showed decreased activities in eight and six cases respectively. 2. Erythrocyte protoporphyrin concentration was below the control range in seven cases. 3. Low AmLev synthase and haem synthase activities were found in one patient with hydrogen sulphide intoxication 1 week after the event. The activities had returned to the control levels 2 months later, though erythrocyte protoporphyrin remained abnormally low. 4. In vitro, hydrogen sulphide inhibited haem synthase with an apparent Ki of 3.4 mmol/l. Sulphide anion, on the other hand, inhibited AmLev synthase activity 85% at 10 mmol/l concentration. Thiosulphate anion inhibited AmLev synthase activity 18% (Ki 27 mmol/l) and haem synthase activity 43% at 10 mmol/l concentration. Selenite inhibited AmLev synthase (Ki 5.1 mmol/l) and haem synthase (Ki 9.0 mmol/l). 5. The assay of AmLev synthase and haem synthase could be a valuable addition to the assessment of workers' health in industries generating hydrogen sulphide or/and methylmercaptan, although the mechanism of the toxic effect remains speculative.

5-Aminolevulinate Synthetase↗
PubMed1982

Spectral and other studies on the intestinal haem receptor of the pig.

We recently demonstrated the presence of a Triton-solubilized high-affinity haem binder on the pig duodenal brush border membrane. The association of haem to the binding factor was determined using radioactive haem and is now studied by a spectrophotometric technique. The binding alters the Soret absorption band of haem from 395 nm to 413 nm. The dissociation constant for the binding of haem to the solubilized binding factor was estimated to be about 10(-9) M by difference spectroscopy. Human serum albumin could not prevent the solubilized binding factor from binding haem. Trypsin digestion destroyed the binder.

Animals↗
PubMed1982

Serum phospholipase A2, immunoreactive trypsin, and trypsin inhibitors during human acute pancreatitis.

Serum immunoreactive trypsin and phospholipase A2 were analyzed at regular intervals in seven patients hospitalized as a result of acute hemorrhage pancreatitis. alpha 1-Antitrypsin and alpha 2-macroglobulin levels and trypsin-inhibitor capacity of serum were determined simultaneously. Serum trypsin concentrations were markedly raised in all patients. The levels of immunoreactive trypsin remained elevated for longer periods than those of urinary amylase. alpha 1-Antitrypsin and trypsin-inhibitor capacity were also significantly increased as compared with the post-illness values, but alpha 2-macroglobulin decreased considerably, reaching the lowest levels on the 5th day after admission. Consequently, phospholipase and trypsin are released to the circulation during hemorrhagic pancreatitis, but the increase in trypsin is compensated for by an increase in trypsin-inhibitor capacity of serum due to elevated alpha 1-antitrypsin levels. The decrease of alpha 2-macroglobulin in hemorrhagic pancreatitis was one of the most interesting findings, and it is proposed that this inhibitor may be consumed in the elimination of proteases through the reticuloendothelial system. The two patients who died had higher phospholipase values than those who recovered, but the prognosis could not be predicted from the values of the other measured variables.

Acute Disease↗
PubMed1982

Comparison of radioimmunological and conventional acid phosphatase assays in the serum of prostatic cancer patients.

Measurements of serum prostatic acid phosphatase concentrations (PAP) by radioimmunoassay (RIA) were compared with the conventional measurements of serum acid phosphatase activities using p-nitrophenylphosphate (pNPP, tot.) and magnesium thymolphthalein monophosphate (TMP) as substrates and L(+)-tartrate (pNPP, tr.) as inhibitor in five prostatic cancer patients before therapy and in 13 during therapy. Elevated serum acid phosphatase activities were detected in 2, 2 and 3 of the 5 untreated patients when using pNPP (tot.), pNPP (tr.) and TMP enzyme assays, respectively. RIA for PAP detected elevated concentrations of the enzyme in 4 of these patients' sera. Three of the patients without metastases and one patient with suspected metastases had elevated concentrations of PAP by RIA. Serum acid phosphatase isoenzyme 2, which is mainly of prostatic origin, was separated chromatographically from serum samples with increased acid phosphatase activity. It represented 60--92% of the total activity, when TMP was used as substrate. Significant correlations (beta less than 0.001) were observed between all conventional enzyme activity measurements used and PAP by RIA within the whole patient group (n = 18), but no correlations existed within the patient group (p = 6) of high normal, or low abnormal serum PAP (2.7--6.6 micrograms/l). In addition, PAP measured by RIA better reflected the clinical state of the 13 patients under treatment than the conventional enzyme assays investigated.

Acid Phosphatase↗
PubMed1982

Inhibition of heme synthase in brain and liver by low-level peroral sulfite exposure.

Male rats given water which contained Na2SO3 0.9 g/l over 1-10 wks ingested a total dose of 41 mmol SO3 per kg body wt. Brain glutathione was above the control at the 1st week and below control at 10 wks. Brain RNA content was below control at the same time. Brain and liver heme synthase were below the control after 7 wks. Although clear effect on the heme synthesis was noted lipid peroxidation could also explain the neurochemical findings.

Animals↗
PubMed1982

Haema synthesis during pyridoxine therapy in two families with different types of hereditary sideroblastic anaemia.

The activity of delta-aminolaevulinic acid synthase (ALA-S) as well as the concentrations of coproporphyrin and protoporphyrin in peripheral red blood cells were examined in 2 sisters and in 2 brothers with hereditary sideroblastic anaemias (HSA) of different types. The measurements were done before and during treatment by pyridoxal-5-phosphate (PLP) and/or pyridoxine chloride. Previous family studies indicated an X chromosome linked HSA in the 2 brothers, whereas the precise mode of inheritance in the 2 sisters has not been established. Previous and present studies have revealed no characteristic defect in haema synthesis in the 2 sisters and their treatment by PLP or pyridoxine produced no haematologic response although a slight stimulation of haema synthesis was observed. In contrast, the 2 brothers showed decreased activity of ALA-S and decreased protoporphyrin concentration in peripheral red blood cells. After treatment by PLP and/or pyridoxine the ALA-S activity was restored to normal. Corresponding to the stimulation of haema synthesis a partial haematological response was observed in both brothers. Stopping and restarting of pyridoxine therapy in one brother confirmed the above results. These observations indicate the presence of two genetically and biochemically different types of HSA and help us to understand the varying response to pyridoxine therapy in this rare disorder.

5-Aminolevulinate Synthetase↗
PubMed1981

Haem biosynthesis in refractory sideroblastic anaemia associated with the preleukaemic syndrome.

The activities of 5 enzymes of the haem biosynthetic pathway and the protoporphyrin concentrations have been measured in peripheral red blood cells of 23 patients having a preleukaemic syndrome with refractory sideroblastic anaemia. A decreased delta-aminolaevulinic acid synthase (ALA-S) activity, an increased uroporphyrinogen I synthase activity and an increased red cell protoporphyrin concentration were consistent findings. Patients with abnormal leucocyte and/or platelet counts in the peripheral blood as well as patients with an excess of blast cells in the bone marrow had the lowest ALA-S activities. A further decrease in ALA-S activity was observed in 3 patients after leukaemic change in the disease. Patients having cytogenetic abnormalities showed no unique enzyme abnormalities. These results indicate that enzymatic disturbances of haem synthesis cannot be used as prognostic indicator of leukaemic transformation in refractory sideroblastic anaemia, but a very low ALA-S activity appears to accompany the development of a leukaemia in such patients.

5-Aminolevulinate Synthetase↗