Biomedical subjects
Publications and source records attributed to P de Moor.
ALL patients with an unexplained high transcortin level (greater than or equal to 3 SD above the normal mean) have a higher incidence of HLA antigen Cw3 than patients with a lower transcortin level. Although both factors are inheritable, their combination occurs only rarely in the family members of these patients.
More unaffected sibs than expected have the same HLA genotypes as their sib with acute leukaemia. This seems not to be due to the restricted heterogeneity in HLA antigens described in the parents of sibs with acute leukaemia.
Serum lipids and apolipoproteins (apo) A-I, A-II, and B were measured in twenty-four patients with severe primary hypothyroidism (Thyrotropin above 40 mU/l), before and during 1-thyroxine treatment. Apo A-I, A-II, and B were assayed by immunonephelometry, using monospecific antisera. The serum levels of total cholesterol (TC), of low-density lipoprotein cholesterol (LDLc), and of the major LDL apoprotein, apo B, were markedly increased in the untreated hypothyroid patients compared to the values during therapy (TC: mean +/- SD, 8.87 +/- 2.9 v. 5.48 +/- 1.6 mmol/l; LDLc: 6.66 +/- 2.6 v. 3.78 +/- 1.4 mmol/l; apo B: 1.66 +/- 0.48 v. 1.14 +/- 0.37 g/l; P less than 0.00001 for all variables). High-density lipoprotein cholesterol (HDLc) was slightly higher before than during therapy (1.58 +/- 0.7 v. 1.31 +/- 0.4 mmol/l; P less than 0.05), while the main HDL apoprotein, apo A-I, was significantly elevated (1.49 +/- 0.42 v. 1.13 +/- 0.27 g/l; P less than 0.0002). The increase of the second major HDL apoprotein, apo A-II, was less pronounced (0.33 +/- 0.1 v. 0.30 +/- 0.08 g/l; P less than 0.022). The apo A-I to apo A-II ratio, which reflects the relative concentrations of the HDL subfractions HDL2 and HDL3, was significantly higher before than during treatment (P less than 0.0006). Serum triglyceride levels were moderately elevated in the untreated hypothyroid patients (1.34 +/- 0.6 v. 0.95 +/- 0.4 mmol/l; P less than 0.002). The small decrease in body weight during therapy did not correlate with the changes of the various lipid and apoprotein parameters.(ABSTRACT TRUNCATED AT 250 WORDS)
Phosphodiesterase activity was studied in cultures derived from 19-day-old rats and enriched with Sertoli cells. Pretreatment of such cultures with follicle-stimulating hormone or L-isoproterenol increased cAMP-phosphodiesterase activity 5.2 and 2.0 times, respectively. cGMP-phosphodiesterase activity was not affected. Similar effects were observed in freshly isolated cells. The stimulatory effect was enhanced by the phosphodiesterase inhibitor 3-isobutyl-1-methylxanthine and was mimicked by cholera toxin and dbcAMP. Increased activity was observed after a latent period of 1 h. Stimulation was blocked by cycloheximide and actinomycin D. The enzyme had an apparent Km for cAMP of 1.4 micro M. Its activity was enhanced by Mg2+ but not by Ca2+. It is concluded that phosphodiesterases play an important role in the hormonal control of Sertoli-cell function and may contribute to the refractory state of these cells after stimulation with various agonists.
Explore the source record for details and available documents.
When Sertoli cell-enriched cultures derived from 19-day-old Wistar rats are exposed to FSH or L-isoproterenol, cAMP accumulates in the medium. Previous contact of cultured cells with either one of these agents results in a reversible state of desensitization. During secondary stimulation up to 20 times less cAMP accumulates in the medium and in the cells. The extent of desensitization depends on the concentration of FSH or L-isoproterenol to which the cells have been exposed and on the duration of this previous contact. Pre-incubation with FSH results in cross-desensitization for L-isoproterenol. Comparable heterologous desensitization is not observed after pre-incubation with L-isoproterenol. This suggests that down-regulation of the respective receptors cannot be the only explanation. Refractoriness can also be induced by dbcAMP. This opens the possibility that cAMP itself contributes to the homologous and heterologous desensitization process.
The aromatization of testosterone has been studied in Sertoli cell-enriched cultures derived from 19-day-old rats. It was found that, besides dbcAMP and FSH, several neurotransmitters have a stimulatory effect. At a concentration of 10(-5) M, the strongest effects were noted with L-isoproterenol, L-norepinephrine, L-epinephrine and D,L-synephrine. Some stimulation was observed with dopamine, whereas histamine, melatonin and serotonin as well as acetylcholine and pilocarpine were ineffective. Experiments with alpha- and beta-adrenergic antagonists suggest that beta 2- and maybe also alpha-receptors are involved. The same maximal level of stimulation was generally observed for dbcAMP, FSH and isoproterenol. No further increase in activity was obtained with combinations of these compounds. It is concluded that adrenergic agonists may play a role in testicular development and function.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
The concentration of the vitamin D-binding protein was measured in human serum by single radial immunodiffusion. Normal serum concentrations were slightly higher in normal women than in normal men. No race-related difference was found between white people from Belgium and black people from Zaire. Lower concentrations were found in cord serum and in patients with cirrhosis of the liver. Increased serum levels were observed during pregnancy or during the intake of estro-progestogens. The serum level of the vitamin D-binding protein was not altered in various diseases of calcium metabolism (primary osteoporosis, primary and secondary hyperparathyroidism, rickets, osteomalacia or vitamin D intoxication). No correlation was found between serum levels of 25-hydroxy vitamin D and those of its binding protein. From these data the following conclusions can be drawn: 1) The serum concentration of the vitamin D-binding protein (about 6.10(-6)M) largely exceeds the normal serum concentration of 25-hydroxy vitamin D (about 4.10(-8)M), so that this protein is normally for less than 1% saturated, 2) Normal serum levels of the vitamin D-binding protein were observed in several diseases of calcium metabolism, and 3) The free concentration of 25-hydroxyvitamin D is not regulated at a constant level.
Explore the source record for details and available documents.
The concentration of transcortin in serum from foetal, neonatal, pregnant and lactating rats was measured by a single radial immunodiffusion method. A decrease in transcortin concentration in sera from foetuses and pregnant rats occurred starting on days 19 and 20 of pregnancy respectively. A more pronounced fall in transcortin concentration in foetal and maternal serum was observed after treating pregnant rats with dexamethasone. These results suggest that corticosterone may be responsible for the observed changes in transcortin concentration.
"Transcalciferin" (the serum transport protein for cholecalciferol and related substances) of two New World monkeys, Cebus apella and Cebus albifrons, was found to be immunologically identical with the transcalciferin of other monkeys and partially with that of man. In contrast with the alpha-globulin mobility of the transcalciferin of other primates, the transcalciferin of cebus monkey has the electrophoretic mobility of albumin. Most of the serum 25-hydroxycholecalciferol was precipitable with isolated monospecific anti-(human transcalciferin) gamma-globulins but not with anti-(human albumin) gamma-globulins. These results indicate that the transport of 25-hydroxycholecalciferol in the cebus monkey is not due to albumin itself but to transcalciferin with the electrophoretic mobility of albumin. Similar variants of transcalciferin also exist in man.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.