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Biomedical subjects

B M Landgren

Publications and source records attributed to B M Landgren.

At least 127 records · Page 7Linked to original sources
PubMed1977

Studies on the pattern of circulating steroids in the normal menstrual cycle. Circadian variation in theperi-ovulatory period.

Circadian variations of the plasma levels of dehydroepiandrosterone, 17-hydroxypregnenolone, pregnenolone and testosterone were investigated by radioimmunoassay in 10 normally menstruating women during the periovulatory period. In seven of the subjects it was also possible to estimate androstenedione and dihydrotestosterone levels. Blood was withdrawn continuously over a period of 48 h at a rate of 4 ml/h by means of a non-thrombogenic pump. The circadian rhythm was studied during 13 3-hour sampling periods (36 h) which were identical in all subjects. Dehydroepiandrosterone, 17-hydroxypregnenolone and pregnenolone showed a marked circadian rhythm with highest mean levels in the morning between 06.00 and 0.900 h and lowest mean levels during the night between 21.00 and 24.00 h. The peak levels of individual subjects coincided completely with the highest mean levels in the case of dehydroepiandrosterone, in 9 out of 10 cases with regard to 17-hydroxypregnenolone and in 8 of 10 cases as far as pregnenolone levels were concerned. The lowest individual levels were more dispersed around the means than were the individual peaks. The difference between the highest (morning hours: 06.00-09.00) and lowest (evening hours: 21.00-24.00) geometeric mean values was 404% for 17-hydroxypregnenolone, 163% for dehydroepiandrosterone and 71% for pregnenolone. The mean testosterone levels also exhibited an elevation between 06.00 and 09.00 h which was significant (P less than 0.05). However, the individual peak values were scattered from 21.00 h of the first day to 18.00 h of the second day. The mean concentrations of androstendine showed a significant increase between 06.00 and 18.00 h. The individual peaks were widely dispersed. Hence a uniform circadian rhythm correlated to the levels of the 5-steroids mentioned above could not be demonstrated in the case of testosterone and androstenedione. An analysis of variance indicated no significant differences between sampling periods as far as dihydrotestosterone levels were concerned. The extent and regularity of the circadian variation in the plasma levels of the 5-steroids studied makes it mandatory to standardize very carefully the exact time of blood withdrawal in any longitudinal study. In view of the sharp changes in the plasma levels during the morning hours, it is suggested that sampling during the afternoon period may provide more constant values.

17-alpha-Hydroxypregnenolone↗
PubMed1977

Trace elements in the human endometrium and decidua. A multielement analysis.

By means of neutron activation analysis, 25 trace elements, which are usually present in biological material, were estimated in 31 specimens of human endometrial tissue obtained at various phases of the menstrual cycle and in 14 specimens of decidua from the 12th to 18th week of pregnancy. Among the 13 trace elements invariably found in all specimens, the levels of copper, potassium, rubidium, antimony and zinc were significantly higher and those of bromine, selenium and sodium significantly lower in the endometrium than in the decidua. No difference was found in the levels of gold, calcium, cobalt, cesium and iron. Among the 12 trace elements which were found only occasionally, chromium, mercury, silver, and cadmium were detected in approximately half and cerium and scandium in approximately one-fourth of the 45 samples studied. Arsenic, barium, lanthanum, molybdenum, samarium and strontium were detected only rarely. The cyclic variations in the endometrial levels of calcium, rubidium and copper were highly significant and those in the levels of gold, cesium, iron, potassium and zinc probably significant.

Adult↗
PubMed1976

Steroid conjugates in human seminal plasma.

A technique for the measurement of five conjugated steroids (dehydroepiandrosterone sulphate, pregnenolone sulphate, testosterone sulphate, dihydrotestosterone sulphate and testosterone glucuronide) in human seminal plasma is described. The steroid sulphates and testosterone glucuronide were measured by radioimmunoassay after solvolysis and enzyme hydrolysis, respectively. In all cases the recognized criteria of assay reliability were fulfilled. In a group of men with established fertility, dehydroepiandrosterone sulphate had the highest concentration and testosterone sulphate had the lowest (mean levels of 1-04 mumoles/1 and 1-52 nmoles/1, respectively). The levels of pregnenolone sulphate, dihydrotestosterone sulphate and testosterone glucuronide were 30-3, 4-37 and 38-8 nmoles/1, respectively. In all cases the levels of conjugated steroid exceeded the levels of the corresponding unconjugated compound.

Adult↗
PubMed1976

Endocrine effects of masturbation in men.

The levels of pregnenolone, dehydroepiandrosterone (DHA), androstenedione, testosterone, dihydrotestosterone (DHT), oestrone, oestradiol, cortisol and luteinizing hormone (LH) were measured in the peripheral plasma of a group of young, apparently healthy males before and after masturbation. The same steroids were also determined in a control study, in which the psychological antipation of masturbation was encouraged, but the physical act was not carried out. The plasma levels of all steroids were significantly increased after masturbation, whereas steroid levels remained unchanged in the control study. The most marked changes after masturbation were observed in pregnenolone and DHA levels. No alterations were observed in the plasma levels of LH. Both before and after masturbation plasma levels of testosterone were significantly correlated to those of DHT and oestradiol, but not to those of the other steroids studied. On the other hand, cortisol levels were significantly correlated to those of pregnenolone, DHA, androstenedione and oestrone. In the same subjects, the levels of pregnenolone, DHA, androstenedione, testosterone and DHT, androstenedione and oestrone. In the same subjects, the levels of pregnenolone, DHA, androstenedione, testosterone and DHT in seminal plasma were also estimated; they were all significantly correlated to the levels of the corresponding steroid in the systemic blood withdrawn both before and after masturbation. As a practical consequence, the results indicate that whenever both blood and semen are analysed, blood sampling must precede semen collection.

Adolescent↗
PubMed1976

Studies on the pattern of circulating steroids in the normal menstrual cycle. I. Simultaneous assays of progesterone, pregnenolone, dehydroepiandrosterone, testosterone, dihydrotestosterone, androstenedione, oestradiol and oestrone.

In an attempt to analyze the multiple changes and interactions in circulating steroid levels in the peri-ovulatory and peri-menstrual periods, the plasma levels of immunoreactive luteinizing hormone (LH), progesterone and unconjugated pregnenolone, dehydroepiandrosterone, testosterone, oestradiol and oestrone were assayed daily during a complete cycle in 17 normally menstruating women. In 14 of the 17 subjects studied androstenedione and unconjugated dihydrotestosterone were also estimated. The day of the LH-peak and the first day of menstruation, respectively, were used to synchronize the peri-ovulatory and peri-menstrual plasma levels of the various steroids. With the exception of dehydroepiandrosterone and dihydrotestosterone, the plasma levels of all steroids exhibited significant, but different changes during the cycle. Testosterone levels showed a slight but significant increase around the LH-peak, whereas the levels of pregnenolone and androstenedione were higher in the post-ovulatory than in the pre-ovulation periods. The levels of oestradiol and oestrone, as well as the ratios of oestradiol to oestrone gradually increased from the low values observed in the early proliferative phase to pre-ovulatory peak values. The relationship between peaks of oestradiol and oestrone and that of LH exhibited great individual variation. The same was true for the individual oestradiol to oestrone ratios. The combination of several steroidal signals did not improve the predictive value of the analyses. However, an increase of individual progesterone values by at least 0.35 ng/ml from the day preceding the LH-peak to the day of the LH-peak was observed in 13 of the 17 subjects. It is suggested that for the early detection of the LH surge and prediction of the subsequent ovulation daily assays of plasma progesterone are of more value than the assay of the other steroids investigated.

Adult↗
PubMed1976

Importance of controlled liquefaction periods for valid steroid assays in human seminal plasma.

Incubation of seminal plasma for different periods up to 24 hours at room temperature resulted in a marked gradual increase in the levels of unconjugated pregnenolone, dehydroepiandrosterone, and testosterone, whereas no alterations were detected in unconjugated dihydrotestosterone and estradiol. No significant difference was observed in the levels of the most sensitive indicators of artifactual changes, pregnenolone and dehydroepiandrosterone, when seminal plasma was frozen immediately or within 30 minutes of ejaculation. It is suggested that, at least when steroid analyses in seminal plasma are contemplated, the samples of ejaculate should be provided by masturbation on hospital premises so that the necessary liquefaction period can be kept short, approximately 30 minutes.

Adolescent↗
PubMed1976

Studies on the pattern of circulating steroids in the normal menstrual cycle. 2. Levels of 20alpha-dihydroprogesterone, 17-hydroxy-progesterone and 17-hydroxypregnenolone and the assessment of their value for ovulation prediction.

Plasma levels of 20alpha-dihydroprogesterone, 17-hydroxyprogesterone and 17-hydroxypregnenolone were assayed daily in 15 normally menstruating women during a complete menstrual cycle. In order to ascertain the normalcy of the cycles studied, LH, progesterone and oestradiol were also determined daily. The pattern of 20alpha-dihydroprogesterone was very similar to that of progesterone. The levels found during the proliferative phase (around 240 pg/ml) increased significantly on the day of the LH-surge and reached values of approximately 3.7 ng/ml at the peak period of luteal activity. The plasma levels of 17-hydroxyprogesterone in the proliferative phase were around 380 pg/ml. The first significant increase occurred one day before the LH-surge and was followed by a sharp peak (approximately 1.5 ng/ml) which coincided with the LH peak. A significant decrease occurred after this peak, which reached a nadir two days after the LH-surge. This was followed by a second rise with a rather broad peak (about 1.8 ng/ml) around the 5th to 7th days after the LH-surge. The levels of 17-hydroxypregnenolone did not show any cyclic variation: from all figures a geometric mean value of 1.62 ng/ml was calulated with tolerance limits at 0.241 and 10.8 ng/ml. Individual day-to-day changes in steroid levels were assessed with regard to their potential for the early identification of the day of the LH-surge. A 17-hydroxyprogesterone value of 1.0 ng/ml, or more, was seen for the first time in the cycle on the day of the LH peak in 13 cycles and a progesterone + 17-hydroxyprogesterone level of at least 1.8 ng/ml in 14 of the 15 cycles studies. These data seem to warrant a study of the predictive value of progesterone and 17-hydroxyprogesterone assays in a much larger population.

17-alpha-Hydroxypregnenolone↗
PubMed1975

Indices of gonadal function in the human male. I. Plasma levels of unconjugated steroids and gonadotrophins under normal and pathological conditions.

A radioimmunoassay technique for the simultaneous measurement of eight unconjugated steroids (progesterone, pregnenolone, dehydroepiandrosterone, androstenedione, testosterone, dihydrotestosterone, oestrone and oestradiol) in the peripheral plasma of human males is described. Determinations of these steroids and of immunoreactive FSH and LH were carried out on the plasma of twenty-one normal individuals and the levels were compared to those of eleven and ten males exhibiting oligospermia and azoospermia, respectively. Mean values and tolerance limits for each hormone, based on a lognormal distribution of individual values, are presented for all groups. Oligospermia was associated with a significant reduction in plasma dihydrotestosterone and testosterone levels. Azoospermic subjects also exhibited decreased dihydrotestosterone levels but a normal range of testosterone concentrations. Mean peripheral plasma levels of FSH were significantly elevated in both pathological groups and this was paralleled in the azoospermic men by increased concentrations of plasma LH.

Adult↗
PubMed1975

Indices of gonadal function in the human male. II. Seminal plasma levels of steroids in normal and pathological conditions.

A radioimmunoassay method developed previously for the measurement of unconjugated pregnenolone, dehydroepiandrosterone, androstenedione, testosterone, dihydrotestosterone and oestradiol in peripheral plasma was applied to the assay of these steroids in seminal plasma of normal, oligospermic and azoospermic males. It was not possible to use the plasma assay method for the determination of progesterone and oestrone in seminal plasma, because some of the reliability criteria were not fulfilled. A detailed analysis of these steroids in the peripheral plasma of the same subjects has been described previously. The levels of all steroids in seminal plasma were significantly lower than the corresponding blood levels. The ratios of blood plasma/seminal plasma levels of the various steroids varied from 37 (testosterone) to 1.7 (dihydrotestosterone). There was a positive correlation between the testosterone and dihydrotestosterone levels of the seminal plasma of normal and azoospermic subjects. The concentrations of dihydrotestosterone, pregnenolone and oestradiol were significantly lower in azoospermic subjects than in normals. The only pathological finding in the seminal plasma of oligospermic subjects was a diminished level of dihydrotestosterone. Enzymic hydrolysis of a seminal plasma pool resulted in a 3- to 8-fold increase in the concentration of pregnenolone, dehydroepiandrosterone, testosterone, dihydrotestosterone and oestradiol, indicating that human seminal plasma contains large amounts of steroid conjugates. It is suggested that the analysis of steroids in the seminal plasma in combination with determinations in peripheral plasma may be a valuable aid to the assessment of testicular function.

Adult↗
PubMed1975

Oestradiol receptor levels in the human fallopian tube during the menstrual cycle.

The levels of cytoplasmic high-affinity oestradiol receptor sites were determined in the isthmus, isthmus-ampulla, ampulla and fimbria of human Fallopian tubes obtained from 23 women during the proliferative and secretory phase of the menstrual cycle and after menopause. Each segment was homogenized in 0.25 M sucrose and fractionated by differential centrifugation into an 800 g X 15 min nuclear pellet and a 100,000 g X 1 h cytoplasmic supernatant and pellet. The nuclear and cytoplasmic pellets were extracted with 0.01 M Tris/HCl pH 8.0 containing 0.25 M sucrose, 1 mM EDTA and 0.1 M KCl. The receptor levels were determined in the 100,000 g X 1 h supernatant (free receptors) and in the KCl extracts (bound receptors). Values are expressed per mug DNA. The concentration of receptors (total, free and bound) was significantly greater in the ampulla than in the isthmus in both phases of the menstrual cycle (P less than 0.001). The concentration of free receptors in the isthmus, isthmus-ampulla and ampulla obtained in the proliferative phase was not significantly different from that of the secretory phase. In the fimbria a significantly higher concentration (P less than 0.01) was observed in the proliferative phase. The bound receptors were significantly higher in all regions in the proliferative phase than in the secretory phase (P less than 0.01). As a consequence the concentration of total receptors was significantly greater along the tube in the proliferative phase (P less than 0.01). The levels of oestradiol in the nuclear pellet of each segment as measured by radioimmunoassay were significantly greater in the isthmic region (P less than 0.01) than in other regions of the tube. The inverse relationship between the concentration of oestradiol receptor sites and the nuclear levels of oestradiol along the Fallopian tube is discussed.

Adult↗