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Biomedical subjects

A van den Ende

Publications and source records attributed to A van den Ende.

At least 37 records · Page 2Linked to original sources
PubMed1990

Bone mineral density after adjuvant chemotherapy for premenopausal breast cancer.

Lumbar bone mineral density (BMD) determination by dual photon absorptiometry was used to study the influence of adjuvant chemotherapy for premenopausal breast cancer on the risk of premature osteoporosis. Six cycles of combination chemotherapy caused ovarian failure in 31 of 44 (71%) women, amenorrhoea mostly already beginning during treatment. In contrast, only seven of 44 (16%) women, who were pair-matched for age and year of breast cancer surgery and had not been treated with chemotherapy, were post-menopausal at the time of measurement. The mean interval after breast surgery was 3.5 years. The significantly decreased BMD in the treated group (1.17 compared to 1.29 g cm-2) could only be explained by the high incidence of menopause in these women, which on average occurred 10 years prematurely. Extrapolation of these findings suggests that adjuvant chemotherapy may precipitate osteoporotic fractures by some 10 years in a considerable proportion of women cured of premenopausal breast cancer.

Adult↗
PubMed1989

Storage of whole blood for up to 24 hours at ambient temperature prior to component preparation.

The effect of rapid cooling to 20-24 degrees C of whole blood immediately after collection, using 'cooling units' with butane-1,4-diol and prolonged storage up to 24 h at ambient temperature was investigated in the whole blood and the subsequently prepared plasma, buffy coat and buffy-coat-poor red cell concentrate (BC-poor RCC) in saline-adenine-glucose-mannitol (SAG M) solution. Factor VIII:C content of the plasma (n = 10), after 24 h storage was 80 +/- 3% of the initial value. In routine procedures factor VIII:C content in the plasma (n = 129 pools of 20 donor units plasma) was 0.77 +/- 0.078 IU/ml, after storage of the whole blood for 16-20 h. In whole blood (n = 10), the 2,3-diphosphoglycerate (2,3-DPG) content of the red cells decreased from 4.36 +/- 0.55 to 1.47 +/- 0.6 mumol/ml red cells after 24 h storage at 20-24 degrees C. After storage of the BC-poor RCC (n = 10) at 2-6 degrees C for 1 week, the 2,3-DPG had dropped to 0.76 +/- 0.46 mumol/ml red cells. During the first 24 h of storage of whole blood, the adenine triphosphate (ATP) levels of the red cells remained stable. A mean increase of 20% of the initial value was observed after addition of SAG M solution. In the BC-poor RCC the ATP slowly decreased to 81 +/- 5% after 5 weeks and to 68 +/- 6.6% of the initial value after 6 weeks storage.(ABSTRACT TRUNCATED AT 250 WORDS)

2,3-Diphosphoglycerate↗
PubMed1989

Storage of leukocyte-poor red cell concentrates: filtration in a closed system using a sterile connection device.

Storage of leukocyte-poor red cell concentrates (LP-RCC) was investigated after filtration in a closed system that was assembled using a Sterile Connection Device (SCD). The LP-RCC were stored for up to 6 weeks following filtration with either 0.9% saline solution (n = 14) or saline-adenine-glucose-mannitol (SAG M) solution (n = 15) to prime and rinse the cellulose acetate filter. The results were compared with the data of nonfiltered buffy-coat-poor red cell concentrates (BC-poor RCC) stored in SAG M solution (n = 10). All LP-RCC contained less than 10(6) leukocytes whereas the nonfiltered BC-poor RCC contained 675 +/- 286 X 10(6) leukocytes at day 1, decreasing to 83 +/- 49 x 10(6) at day 42. Although glucose consumption, lactic acid production and decrease in pH was similar from day 7 through 28 in both groups of LP-RCC, a significantly steeper decline of ATP values as well as a higher hemolysis and LDH release was observed in the LP-RCC filtered with saline. During storage of the nonfiltered BC-poor RCC in SAG M, significantly higher glucose consumption (p less than 0.01), LDH release (p less than 0.001), rate of hemolysis (p less than 0.001) and a lower pH (p less than 0.001) were found, compared to the filtered units. It is postulated that the leukocytes present in the nonfiltered BC-poor RCC were responsible for these differences. The ATP values in the SAG-M-filtered and nonfiltered BC-poor RCC in SAG M were comparable.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenine↗
PubMed1988

Preparation of leukocyte-poor platelet concentrates from buffy coats. III. Effect of leukocyte contamination on storage conditions.

To study the influence of contaminating leukocytes on the storage conditions of platelet concentrates (PC), various amounts of leukocytes were added to identical PC. From 12 blood donations, 12 leukocyte-poor PC were prepared and pooled. Subsequently, the pool was divided into 12 identical PC. The plasma volume of the PC was 58.6 +/- 0.6 ml, the platelet concentration was 1.01 +/- 0.04 x 10(9)/ml (mean +/- SD) and the red cell contamination did not exceed 10(7) per PC. To 4 groups of 3 PC, pooled leukocytes were added from the same 12 blood donations. The leukocyte contamination for each group of 3 PC was 0.14 +/- 0.05, 1.96 +/- 0.09, 5.53 +/- 0.98 and 13.0 +/- 0.93 x 10(6)/ml (mean +/- SD) for groups I-IV, respectively. The PC were stored for 7 days at 22 degrees C in normal polyvinylchloride bags. A significant correlation was found between increasing concentrations of leukocytes in the PC and the drop in pH (r = -0.93), glucose consumption (r = -0.91), lactic acid production (r = 0.93) and release of lactate dehydrogenase (r = 0.92) during storage of the PC. The excretion of beta-thromboglobulin, depletion of platelet adenine nucleotides, decreased ability to incorporate 3H-adenosine into metabolic nucleotides and poor morphology of the platelets were also significantly correlated with an increased number of leukocytes in the PC. These data show that high concentrations of leukocytes in PC have a significant detrimental effect on the viability of platelets during storage at 22 degrees C. We conclude that for good storage conditions of PC, the upper limit of leukocytes per PC should not exceed 10(7).

Blood Platelets↗
PubMed1987

Determination of urinary cystine for monitoring anticystinuric therapy.

Cystine is assayed in urine by a method adapted from the procedure of Haux and Natelson (Clin Chem 1970;16:366-369) and modifications of the method, which improved its specificity, are presented. Assay imprecision (CV) at four different cystine concentrations (range: 0.042-1.658 mmol/l) varied from 23.1% to 3.7%. Analytical recovery was 94.6 +/- 6.0%. D-Penicillamine, alpha-mercaptopropionylglycine, L-glutamine and metabolites, added to urine, had negligible effect on the results of the cystine assay. Samples were stable for 3 wk when stored at 4 degrees C or frozen. Cystine excretion (mmol/24 h) in apparently healthy persons ranged from 0.041 to 0.170 (mean +/- SD: 0.099 +/- 0.039). Cystine excretions are presented in patients treated with anticystinuric drugs.

Amino Acids↗
PubMed1986

Comparative effects of monophasic desogestrel plus ethinyloestradiol and triphasic levonorgestrel plus ethinyloestradiol on lipid metabolism.

The effects of the monophasic oral contraceptive preparation desogestrel plus ethinyloestradiol (EE) and triphasic levonorgestrel plus EE on lipid metabolism were compared. Sixteen young healthy female volunteers received monophasic desogestrel plus EE (21 X 150/30), whereas eighteen women received triphasic levonorgestrel plus EE (6 X 50/30 + 5 X 75/40 + 10 X 125/30) for six consecutive cycles. The lipid composition of the various lipoprotein fractions was estimated after separation in a density gradient by ultracentrifugation. In addition, the apolipoproteins A-I and B were assessed. HDL-cholesterol (precipitation method), HDL-2 cholesterol, HDL-2 phospholipids and the ratio apolipoprotein A-I to apolipoprotein B were significantly higher in the monophasic desogestrel group than in the triphasic levonorgestrel group after three and six treatment cycles. HDL-cholesterol (gradient), HDL-phospholipids (gradient), HDL-3 phospholipids and apolipoprotein A-I were only significantly higher after six treatment cycles. No differences between the groups were observed for the other lipid variables studied including triglycerides and VLDL-triglycerides.

Adult↗
PubMed1986

Bone metabolism in rheumatoid arthritis compared with postmenopausal osteoporosis.

Calcium and bone metabolism in 29 rheumatoid arthritis (RA) patients were compared with those in 27 postmenopausal osteoporotic patients. Signs of vitamin D deficiency were found in 20 RA patients, including 12 who took recommended amounts of vitamin D in their diets and were exposed to sufficient sunlight, and in none of the osteoporotic patients. There were no signs of malabsorption. In six out of 15 patients we found increased liver enzyme activity, which may have a role in vitamin D metabolism. We propose the influence of non-steroidal anti-inflammatory drugs (NSAIDs) on vitamin D metabolism in the liver as a possible explanation.

Arthritis, Rheumatoid↗
PubMed1986

Blood level, excretion, and metabolite pattern of [14C]-brotizolam in humans.

Following a single oral dose of 14C-labeled brotizolam (2-bromo-4-(2-chlorophenyl)-9-methyl-6H-thieno[3, 2-f]-1,2,4-triazolo[4,3-a]-1,4-diazepine. We 941, Lendormin) the plasma level concentration and the total excretion of the radioactivity as well as the plasma level of the unchanged substance was measured in 4 healthy subjects. [14C]-Brotizolam was rapidly absorbed. The elimination half-life of the radioactivity from the plasma was 9.5 h, that of the unchanged [14C]-brotizolam 4.4 h. Using a two-compartment open model, the stimulation of giving 0.5 mg of the drug once daily showed no accumulation of brotizolam and its metabolites. Within the 4-day study 64.9% of the given radioactivity was eliminated renally. The total excretion was 86.5% of the dose. Extraction and thin layer chromatographic fractionation of the renally excreted radioactivity indicated two major metabolites one of which predominated. The metabolites were completely conjugated. Unchanged [14C]-brotizolam was excreted in minor amounts below 2-3% of the dose.

Adult↗
PubMed1985

Pharmacokinetics of transdermally delivered clonidine.

We detail a series of pharmacokinetic investigations to determine the dose linearity, the effect of site of application, the duration of steady-state plasma concentrations, and the effect of chronic application when clonidine is administered transdermally. Dose linearity was assessed in six subjects with normotension after application of increasing sizes of transdermal clonidine systems (3.5, 7.0, and 10.5 cm2 size) to the upper outer arm. Of the six subjects studied, five had linear relationships between clonidine plasma concentrations at steady state and system size of greater than 0.975; in the sixth subject the correlation was greater than 0.90. The mean steady-state plasma concentrations with 3.5, 7.0, and 10.5 cm2 systems were 0.39, 0.84, and 1.12 ng/ml, respectively. The influence of site and duration of application on the absorption of transdermal clonidine was studied in eight subjects with normotension by use of the 3.5 cm2 system. The mean steady-state plasma concentration over the time interval from 3 to 7 days after application to the arm or to the chest did not significantly differ. When a system was left on the chest or arm for a total of 11 days (4 days beyond the recommended time to change systems), the plasma concentrations of seven of eight subjects with application to the arm and of six of eight subjects with application to the chest remained constant through day 11. The influence of consecutive applications of 3.5 cm2 transdermal clonidine systems on steady-state plasma clonidine concentrations was also studied in eight subjects with normotension over an 11-day period.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Topical↗
PubMed1985

Urinary creatine: biochemical indicator for evaluation of sickle cell crises.

In a patient with known sickle cell beta 0-thalassemia we measured serum lactate dehydrogenase (LD) activity and 24-h urinary creatine excretion rate as markers to evaluate sickle cell crises. We believe that a distinction based on biochemical findings can be made between hemolytic and painful vaso-occlusive sickle cell crises with muscular involvement. To assess hemolytic crises by objective biochemical measures, we have used assay of LD activity, and to assess painful crises with muscular involvement objectively, the 24-h urinary creatine excretion rate. We conclude that hemolytic crises are characterized by high serum LD activities. Furthermore, we conclude that--at least in this patient--painful crises are accompanied by high 24-h urinary creatine excretion rates. Our findings suggest that muscle involvement may play an important role in painful vaso-occlusive sickle cell crises.

Adult↗
PubMed1984

Excretion of (sulfated) steroids in the urine and excretion of cholesterol sulfate in the feces of boys with recessive X-linked ichthyosis.

The excretion of sulfated steroids was investigated in the urine and feces of six boys aged 9 months to 7 years and 10 months who had recessive X-linked ichthyosis. Profiles of urinary total steroids as well as sulfated steroids were normal. Cholesterol sulfate excretion in the urine was not elevated. In the feces 2-20% of total cholesterol was cholesterol sulfate, whereas in the feces of 28 healthy children no cholesterol sulfate was demonstrable. In the 6 patients total cholesterol excretion (500-2,500 mumol/kg feces) was also elevated in comparison with the 28 healthy controls (150-700 mumol/kg feces, mean 365 mumol/kg feces).

Child↗
PubMed1982

Improved extraction procedure for determination of bile acids in faeces.

A simplified extraction procedure for bile acids from wet faeces, using methanol/hydrochloric acid is described. Extracts were analyzed by gas-liquid chromatography, thin-layer chromatography and an enzymatic assay, with 3 alpha-hydroxysteroid dehydrogenase. Recoveries of some stable bile acids, added to faeces, were studied; extraction efficiency was also investigated with a procedure using radioactive labelled bile acids given orally to patients. Resin treatment of faecal extracts, because of the sometimes hard colour of the extracts, resulted in a slightly lower recovery as determined by the enzymatic method. Recoveries were higher, using the proposed extraction procedure, than those obtained with extracts prepared by the standard procedure of Grundy et al [6].

3-Hydroxysteroid Dehydrogenases↗
PubMed1981

Effect of cyproterone acetate on pituitary-adrenocortical function in man.

Recent literature (1973-1976) suggests suppression of pituitary-adrenal function in patients (eg with pubertas praecox) who are treated with cyproterone acetate in high doses for prolonged periods. Therefore we investigated in our metabolic ward the effects of administration of 200 mg cyproterone acetate per day during 20 days to 4 healthy male volunteers. Baseline plasma cortisol and ACTH levels, repeated diurnal plasma cortisol and ACTH profiles and the results of tetracosactide (Synacthen) stimulation tests and single-dose metyrapone (Metopiron) tests proved to be comparable before, during and after treatment. Moreover, a slight gradual increase in urinary cortisol excretion during the observation period indicated that cyproterone acetate in the given dose during 20 days certainly does not reduce the pituitary-adrenal function of 4 healthy male volunteers. Long-term administration (during 1 to 7 years) of the combination of cyproterone acetate and ethinyloestradiol did not suppress serum levels of cortisol, prolactin, thyroxine and TSH in 18 female patients with hirsutism and/or acne.

Adrenocorticotropic Hormone↗
PubMed1980

Subpopulations of T lymphocytes from human blood differing in density and stage of maturation.

Previous investigations have shown that peripheral lymphocytes with a low specific gravity are much more active than are heavy lymphocytes in the proliferative response towards mitogens, antigens and allogeneic lymphocytes. We have now studied the biological significance of this difference in human peripheral T lymphocytes with two independent parameters generally regarded as maturation criteria. Heavy human T lymphocytes contain about one-third of the amount of cyclic AMP found in light T cells, but the increase in cyclic AMP produced by isoproterenol or prostaglandin E1 is much higher in the heavy T cells. The lactate dehydrogenase isoenzyme pattern of heavy human T lymphocytes is intermediate between that of human thymocytes and light T lymphocytes, the latter showing the most mature pattern. A high correlation was found between these two parameters, the cell density and the reactivity towards phytohemagglutinin. We conclude that human peripheral T lymphocytes are heterogeneous in maturation level: heavy, nonreactive T lymphocytes are less mature than light T lymphocytes.

Cell Differentiation↗