Biomedical subjects

L Hummer

Publications and source records attributed to L Hummer.

At least 19 recordsLinked to original sources

PubMed1986

Serum vitamin D metabolites are not related to growth rate, bone mineral content, or serum alkaline phosphatase in male puberty.

Twenty boys were followed during their puberty for about 2 years with examinations every third month. At each examination we determined serum concentrations of 25OHD3, 1,25(OH)2D3, 24,25(OH)2D3, 25.26(OH)2D3, alkaline phosphatase (AP) and testosterone together with bone mineral content (BMC) at the distal forearm. Highly significant increases in both BMC (P less than 0.001), serum AP (P less than 0.001), and peak height velocity (PHV) followed the increase in serum testosterone. The boys were grouped according to time of maximal increase in BMC, AP, and PHV. The serum levels of the vitamin D metabolites were related to these points. No significant changes in any of the serum vitamin D metabolites were found. Thus vitamin D metabolism does not seem to be significantly influenced during the period of life when both the linear growth and bone mineralization is maximal.

24,25-Dihydroxyvitamin D 3↗

PubMed1986

Different metabolism of vitamin D2/D3 in epileptic patients treated with phenobarbitone/phenytoin.

Serum concentrations of vitamin D metabolites were measured before and during treatment with either vitamin D2 or vitamin D3, 4000 IU per day for 24 weeks, in 22 epileptic outpatients receiving phenobarbitone/phenytoin. The serum concentration of total 1,25(OH)2D did not change during the treatment period in any of the treatment groups. On the other hand, in the vitamin D2 group, serum 25(OH)D2, total 25(OH)D, and 24,25(OH)2D increased significantly during the trial, whereas serum concentrations of the vitamin D3 metabolites were unchanged. In the vitamin D3 group, serum concentrations of the vitamin D3 metabolites increased significantly, whereas the vitamin D3 metabolite levels remained unchanged. However, vitamin D3 treatment resulted in a 2-4-fold greater increase in serum concentrations compared to vitamin D2 treatment. Treatment with vitamin D2 and vitamin D3 in the same dose in IU results in considerably different serum concentrations of the vitamin D metabolites.

24,25-Dihydroxyvitamin D 3↗

PubMed1986

Serum levels of vitamin D metabolites and testosterone in male puberty.

We determined the serum concentrations of 25-hydroxyvitamin D, 1,25-dihydroxyvitamin D [1,25-(OH)2D], 24,25-(OH)2D, and 25,26-(OH)2D every third month in a 2-yr longitudinal study of 20 normal pubertal boys. Seasonal fluctuations and highly significant correlations with the hours of sunshine were found for 25-hydroxyvitamin D, 24,25-(OH)2D and 25,26-(OH)2D, whereas the serum concentrations of 1,25-(OH)2D were not related to sunshine duration. The boys were grouped according to the time at which the maximal increase in serum testosterone occurred, and the serum vitamin D metabolite levels were examined in relation to this point. No significant changes in the serum levels of the vitamin D metabolites were found. When compiling the data according to clinical evaluation of puberty estimated by pubic hair stages (PH1 to PH4), no significant changes in the serum levels of vitamin D metabolites were found. The present data indicate that the marked increase in serum testosterone in male puberty has no significant influence on circulating vitamin D metabolite levels.

Child↗

PubMed1986

Serum concentration of vitamin D metabolites during treatment with vitamin D2 and D3 in normal premenopausal women.

Serum concentrations of vitamin D metabolites were measured in 19 healthy premenopausal women before and during treatment with 4000 IU per day of either vitamin D2 or vitamin D3 for 8 weeks. Vitamin D2 treatment increased the serum concentration of 25(OH)D2, but a corresponding decrease in 25(OH)D3 resulted in an unchanged value for total 25(OH)D. The serum concentration of the D3 dihydroxy metabolites was also significantly decreased. Vitamin D3 treatment increased the serum concentrations of 25(OH)D3 and D3 dihydroxy metabolites. The serum concentration of 1,25(OH)2D did not change in either of the treatment groups. We conclude that vitamin D2 and vitamin D3 given in the same doses in international units have a different effect on the serum concentration of vitamin D metabolites and biochemical indices of calcium metabolism.

Adult↗

PubMed1985

Cerebrospinal fluid ACTH as a marker of central nervous system metastases from small cell carcinoma of the lung.

Adrenocorticotrophic hormone (ACTH) concentrations were measured in the plasma and cerebrospinal fluid (CSF) of 107 consecutive patients with known or suspected central nervous system (CNS) metastases secondary to small cell carcinoma of the lung. The combined results of computerized tomography scans, neurologic examination, and autopsy were used to determine the presence or absence of CNS metastases. On the basis of such an assessment, definitive conclusions were possible in 77 patients. CNS metastases were present in 52 cases and absent in 25. The median CSF ACTH level was 30 ng/ml in both groups. None of five patients with very high CSF ACTH concentrations had elevated ACTH concentrations in plasma. Considering the 95th percentile of patients without CNS metastases as the upper limit of normal, 12 patients with metastases and one without had an elevated CSF ACTH value. Eleven patients with leptomeningeal carcinomatosis (MC) did not constitute a special subgroup in this respect. The median ratio of CSF ACTH and plasma ACTH was 1.0 in patients with CNS metastases and 0.4 in those without (P less than 0.05). Patients with MC had a median ratio of 1.3, which was significantly different from that of both of the other groups (P less than 0.05). Ten patients with CNS metastases (one with MC) and one without exceeded the upper 95th percentile of the CSF/plasma (ACTH) ratio in patients without CNS metastases. The significance levels of these findings disappeared, however, when patients with signs of an elevated ACTH concentration in plasma were excluded. Patients with ectopic ACTH production into CSF do not necessarily have ectopic ACTH production outside the CNS, despite the presence of extracerebral metastases. With the criteria employed in this study, an elevated level of CSF ACTH diagnosed too few patients for the authors to recommend its determination as a single test in diagnosing CNS metastases or MC secondary to small cell carcinoma of the lung.

ACTH Syndrome, Ectopic↗

PubMed1985

The effects of age and body composition on circulating serum oestrogens and androstenedione after the menopause.

Circulating levels of oestrone, oestradiol and androstenedione were measured in two large groups of postmenopausal women, in one group the women were between 46 and 56 years of age and in the second, older group they were 70 years of age. In addition the fat mass was calculated from the height, weight and age of the women. Serum concentrations of both oestrogens did not change with age, whereas the serum androstenedione concentration decreased significantly. A change in body composition included decreased height and increased fat mass in the older group. Serum concentrations of both oestrogens correlated significantly with the fat mass and serum androstenedione as well as with each other. From the correlation analysis it may be concluded that the conversion rate of androstenedione to oestrone, and of oestrone to oestradiol, increases with age, which presumably explains the unchanged concentrations of the circulating oestrogens in relation to postmenopausal age, although the precursor decreases during the same period.

Age Factors↗

PubMed1985

Different metabolism of vitamin D2 and vitamin D3 in epileptic patients on carbamazepine.

Serum concentrations of vitamin D metabolites were measured in 30 epileptic outpatients on monotherapy with carbamazepine before and during treatment with either vitamin D2 or vitamin D3, 4000 IU per day for 24 weeks. Vitamin D2 treatment increased the serum concentration of 25OHD2, but a corresponding decrease in 25OHD3 resulted in an unchanged serum value of total 25OHD. Vitamin D3 treatment increased the serum concentration of 25OHD3. The resulting serum level of 25OHD was consequently twice the level of that in the D2-treated group. The serum concentrations of the dihydroxy metabolites showed a similar difference between the 2 treatment groups. We conclude that treatment with vitamins D2 and D3 in the same doses produces considerably different serum concentrations of vitamin D metabolites. If the present findings can be extrapolated to normal subjects, it is important to consider more carefully which D-vitamin should be used, both with regard to therapy and supplementation.

Adult↗

PubMed1985

Determination of mono- and dihydroxy-vitamin D metabolites in normal subjects and patients with different calcium metabolic diseases.

Reliable assays to determine the vitamin D metabolites are useful aids in the study of disorders involving vitamin D metabolism, and in the evaluation of the response in patients receiving vitamin D treatment. We report here the establishment in our laboratory of a method capable of measuring 25(OH)D, (including 25(OH)D2 and 25(OH)D3), 1,25(OH)2D and 24,25(OH)2D in a single blood sample. The method involves methanol/dichloromethane extraction and Sephadex LH-20 chromatography. The monhydroxylated fraction was purified on Lipidex 5000 and separated in 25(OH)D2 and 25(OH)D3 on high pressure liquid chromatography (HPLC), followed by ultra violet absorbance (UV) detection. The dihydroxylated fraction was separated by HPLC and quantified by protein-binding assays. The method is precise and accurate. The vitamin D metabolites were measured in different groups of patients and in normal subjects.

24,25-Dihydroxyvitamin D 3↗

PubMed1985

Discrepancy between serum 1,25-dihydroxycholecalciferol measured by radioimmunoassay and cytosol radioreceptor assay.

A radioimmunoassay for determination of 1,25-dihydroxycholecalciferol (1,25(OH)2D3) in serum, was compared with the radioreceptor assay using cytosol receptor from rachitic chick intestine in order to clarify whether differences in specificity can explain discrepancies in the clinical application of the two techniques. In the literature, seasonal fluctuations in serum 1,25(OH)2D3 are only observed when using radioimmunoassay. Treatment of anticonvulsant osteomalacia with vitamin D3 results in a marked increase in radioimmunologically measured 1,25(OH)2D3, but no effect on the serum 1,25(OH)2D level, measured by the radioreceptor assay, could be observed. The present study demonstrates that another unknown compound is coeluted on high pressure liquid chromatography with 1,25(OH)2D3, and recognised only by the antiserum. It can be concluded that the present radioimmunoassay cannot replace the cytosol receptor assay or either supplement by measuring the 1,25(OH)2D3 metabolite only.

Adult↗

PubMed1985

Treatment with vitamin 24,25 (OH)2D3 does not change serum levels of 1,25 (OH)2D or urinary calcium excretion rate in man.

40 healthy early postmenopausal women participated in a controlled therapeutic trial with the aim of examining whether treatment with 24,25 vitamin D3 changed the serum concentration of either 1,25 (OH)2D and/or the 24-hour urinary calcium excretion rate. The 40 women were randomized to treatment with either 24R,25 (OH)2D3 (10 micrograms daily) or placebo. Serum concentrations of calcium, 25 (OH) D, 1,25 (OH)2D, 24,25 (OH)2D3 and 24-hour urinary calcium excretion rate were measured before (t0) and after (t1) 6 months of treatment. In the 24,25 (OH)2D3 treated group there was a highly significant increase in the mean serum 24,25 (OH)2D3 concentration, whereas serum 25 (OH) D and 1,25 (OH)2D and serum and urinary calcium were unchanged during the trial. In the placebo group all values were similar before and after the trial. We conclude that treatment with 24,25 (OH)2D3 is not an alternative to conventional treatment of renal hypercalciuria.

24,25-Dihydroxyvitamin D 3↗

PubMed1984

Measurement of 25-hydroxyvitamin D3 and 25-hydroxyvitamin D2 in clinical settings.

A quick and simple method for the selective measurement of 25-hydroxyvitamin D3 (25OHD3) and 25-hydroxyvitamin D2 (25OHD2) is described. It includes a rapid sample preparation technique and a combination of a selective radioimmunoassay for 25OHD3 and a competitive protein-binding assay using vitamin D-binding protein for the determination of total 25OHD, including 25OHD3 and 25OHD2. The method was compared with a procedure which include methanol/methylene chloride extraction and chromatography on Sephadex LH 20, and a procedure which includes HPLC and final quantification by u. v. detection. The methods were applied to three groups of patients in order to obtain information on how far assay procedures could be simplified for use in the clinical settings. It is concluded that the method described is applicable for following patients on vitamin D2 therapy. When groups of patients have to be compared, the mean values of the estimates are comparable, whether a simple method or a laborious method is used. Hence, the selection of assay method should take into account the clinical problem and the cost of the analysis.

25-Hydroxyvitamin D 2↗

PubMed1984

A sensitive and selective radioimmunoassay for serum 24,25-dihydroxycholecalciferol in man.

We have developed a sensitive and selective radioimmunoassay for 24,25-dihydroxycholecalciferol (24,25(OH)2D3). Antisera with a high titre and affinity to 24,25(OH)2D3 were raised in rabbits immunized with a protein conjugate of the 3-hemisuccinate derivative of 24,25(OH)2D3. Serum samples were extracted by methanol/dichloromethane and the lipid extracts purified on Sephadex LH 20 and chromatographed by single step HPLC on a straight phase silica column. The radioimmunoassay is capable of measuring 24,25(OH)2D3 in the '24,25(OH)2D complex' isolated by HPLC and containing the comigrating metabolites: 24,25(OH)2D3, 24,25(OH)2D2, 25(OH)D3-26,23 lactone and 25,26(OH)2D2. The detection limit of 2 pg/assay tube is a marked improvement, compared to the competitive protein binding assay using rachitic rat serum. Measured by the radioimmunoassay 24,25(OH)2D3 ranged from 0.05 to 1.96 ng/ml with a mean of 0.85 ng/ml in 34 healthy adults. For comparison 24,25(OH)2D, measured simultaneously by competitive protein binding with rachitic rat serum, ranged from 0.1 to 4.0 ng/ml with a mean of 1.76 ng/ml.

24,25-Dihydroxyvitamin D 3↗

PubMed1984

Longitudinal study of calcium metabolism in male puberty. II. Relationship between mineralization and serum testosterone.

Height velocity, bone mineral content (BMC), serum concentrations of alkaline phosphatase (AP), testosterone, dehydroepiandrosterone (DHEA) and androstenedione (A-dione) were determined as a part of a longitudinal study of calcium metabolism in normal male puberty. The time of maximal increase (Tm) in concentrations was calculated for 20 boys from a curve-fitting analysis program. Highly significant correlations were found between Tm testosterone and Tm BMC (r = 0.73, p less than 0.001); Tm AP and Tm BMC (r = 0.68, p less than 0.001). The mean difference in time between Tm testosterone and Tm BMC was 4.7 months and between Tm AP and Tm testosterone 0.7 month. Our data indicate a very close relationship between testosterone, osteoblastic activity, and mineralization in normal male puberty, whereas the adrenal androgens do not seem to have a major influence on the mineralization at the male puberty growth spurt phase.

Adolescent↗

PubMed1984

Somatomedin A in male puberty. Variation with age, maturity, growth and androgens.

Bioassayable somatomedin-A (SM-A) and serum concentrations of testosterone (T) and dehydroepiandrosterone (DHEA) were determined longitudinally in 26 normal boys during puberty. The mean trend of SM-A increased in relation to age, pubic hair development and peak height velocity (PHV) and significant correlations were observed with testicular volume, height velocity and T (all P less than 0.001) but not with DHEA. In relation to growth SM-A increased mainly during 12 to 6 months prior to PHV but no further increase was seen in the 6 months thereafter. Thus pubertal growth and development have to be taken into account in the evaluation of changes in bioassayable SM-A concentrations in boys.

Age Factors↗

PubMed1984

A selective and simplified radioimmunoassay of 25-hydroxyvitamin D3.

A simple, non-chromatographic and selective assay for determination of 25OHD3 in serum is described. The serum sample is deproteinated with acetonitrile and the supernatant purified over a small prepacked cartridge, Sep-pak. In the eluate from the cartridge, 25OHD3 is measured by radioimmunoassay. The selectivity of the assay for 25OHD3 is improved by adding vitamin D2 to the antiserum; the assay is thus capable of measuring 25OHD3 in serum samples containing up to a ratio of 25OHD2/25OHD3 equal to 150. The simplicity, speed and the small amount of sample needed (0.5 ml) make this method suitable for use in a routine clinical laboratory. Because of its selectivity for 25OHD3 the assay is a necessary prerequisite in the further investigation of metabolic discrimination between vitamins D2 and D3.

Calcifediol↗

PubMed1983

Demonstration of autoantibodies against ACTH in serum from a patient with cancer of unknown origin.

We report the presence of autoantibodies against ACTH in plasma from a 46 year old man with poorly differentiated adenocarcinoma of unknown origin. There was no evidence of Cushing's syndrome. By radioimmunoassay and immunocytochemical technique the antibodies were found to possess specificity against the 13-24 aminoacid sequence of ACTH. This sequence includes the biologically active site. On the basis of our findings it is discussed whether the presence of the autoantibodies could reflect a fundamental immunological disturbance primarily or secondarily related to cancer.

Adenocarcinoma↗

PubMed1983

Unchanged biochemical indices of bone turnover despite fluctuations in 1,25-dihydroxyvitamin D during the menstrual cycle.

To examine the effect of endogenous oestrogens on calcium metabolism during the menstrual cycle, fasting blood and urinary samples were obtained every day throughout the menstrual cycle in 5 young women. Bone turnover was estimated by serum alkaline phosphatase and fasting urinary excretions of hydroxyproline and calcium. Serum levels of oestradiol (E2), oestrone (E1), and androstenedione (A) showed the well known cyclic fluctuations, the serum 1,25-dihydroxyvitamin D (1,25(OH)2D) nearly doubled from the early follicular phase to the time of ovulation, although 25-hydroxyvitamin D (25OHD) and 24,25-dihydroxyvitamin D (24,25(OH)2D) were almost unchanged. No correlation between the rise in the serum 1,25(OH)2D level and the measured parameters of calcium metabolism was observed. In view of these findings, the 1,25(OH)2D3 serum concentration measured in women with functioning ovaries can only be interpreted in the context of the menstrual cycle. The published normal range in women for the metabolite may also require reinterpretation.

Adult↗

PubMed1983

An easy and reliable radioimmunoassay of serum androstenedione: age-related normal values in 252 females aged 2 to 70 years.

A simple, non-chromatographic radioimmunoassay for the measurement of androstenedione (A-dione) in serum and based on a commercially available antiserum is described. The antibody-bound fraction was separated from the free fraction by a gel-centrifugation procedure. The method was used to establish reference values for normal females, based on determination in 252 normal females from 2 to 70 years of age. The data support the statement that the decline with age after puberty in the overall production of A-dione is mainly caused by a reduction in the adreno-derived A-dione, since the mean concentration of A-dione in age-matched pre- and postmenopausal women was very similar

Adolescent↗