The pulsatile secretion of bioactive luteinising hormone in normal adult men

1990 ◽  
Vol 122 (5) ◽  
pp. 643-650 ◽  
Author(s):  
J. Alan Talbor ◽  
R. Stuart ◽  
C. Rodger ◽  
Steven M. Shalet ◽  
Malcolm D. Littley ◽  
...  
Keyword(s):  
Temporal Relationship ◽  
Mean Amplitude ◽  
Adult Men ◽  
Lh Pulsatility ◽  
The Mean ◽  
Normal Men ◽  
Relationship Of ◽  
Low Amplitude ◽  
Mouse Leydig Cell

Abstract. We have studied bioactive and immunoreactive LH pulsatility in 11 normal men. The temporal relationship of plasma LH, testosterone, and FSH were also investigated. Blood samples were taken at 10-minute intervals for 6 h and bioactive LH levels were determined using an in vitro mouse Leydig cell bioassay. Testosterone, LH and FSH were determined by standard radioimmunoassay. Twenty-two bioactive LH pulses were detected (amplitude 8.5±4.9 IU/l, mean±sd) with a frequency of 2±0.8/6 h compared with only 18 immunoreactive LH pulses (amplitude of 3.6±1.8 IU/l) and a frequency of 1.6±0.5/6 h. Bioactive:immunoreactive LH ratios increased (p<0.01) from the preceding pulse nadirs (2.26, range 1.66-4.28) to the pulse peaks (2.71, range 1.99-4.67). Twenty FSH pulses (seen in all but one subject) of low amplitude (0.7±0.6, median 0.5 IU/l) were also present. There was a close temporal relationship between testosterone and FSH secretion with bioactive and immunoreactive LH pulses with lags of 30-60 and 0 min, respectively. We conclude that immunoreactive LH pulses are discordant from bioactive LH pulses in 18% of occasions. Further, the mean amplitude of bioactive episodes were approximately 2.6 times greater than that of immunoreactive episodes, whereas interpulse period and pulse duration were similar. The increase in bioactive:immunoeactive ratio at pulse peaks may indicate that in normal men LH pulses are enriched with a more biopotent form of the molecule.

TNF-α and myocardial depression in endotoxemic rats: temporal discordance of an obligatory relationship

1998 ◽  
Vol 275 (2) ◽  
pp. R502-R508 ◽  
Author(s):  
Xianzhong Meng ◽  
Lihua Ao ◽  
Daniel R. Meldrum ◽  
Brian S. Cain ◽  
Brian D. Shames ◽  
...  
Keyword(s):  
Temporal Relationship ◽  
Contractile Function ◽  
Myocardial Depression ◽  
Tnf Α ◽  
Myocardial Contractile ◽  
Factor Α ◽  
Relationship Of

Exogenous tumor necrosis factor-α (TNF-α) induces delayed myocardial depression in vivo but promotes rapid myocardial depression in vitro. The temporal relationship between endogenous TNF-α and endotoxemic myocardial depression is unclear, and the role of TNF-α in this myocardial disorder remains controversial. Using a rat model of endotoxemia not complicated by shock, we sought to determine 1) the temporal relationship of changes in circulating and myocardial TNF-α with myocardial depression, 2) the influences of protein synthesis inhibition or immunosuppression on TNF-α production and myocardial depression, and 3) the influence of neutralization of TNF-α on myocardial depression. Rats were treated with lipopolysaccharide (LPS, 0.5 mg/kg ip). Circulating and myocardial TNF-α increased at 1 and 2 h, whereas myocardial contractility was depressed at 4 and 6 h. Pretreatment with cycloheximide or dexamethasone abolished the increase in circulating and myocardial TNF-α and preserved myocardial contractile function. Similarly, treatment with TNF binding protein immediately after LPS prevented myocardial depression. We conclude that endogenous TNF-α mediates delayed myocardial depression in endotoxemic rats and that inhibition of TNF-α production or neutralization of TNF-α preserves myocardial contractile function in endotoxemia.

An investigation of LH pulsatility in burned men by bioassay and radioimmunoassay

1992 ◽  
Vol 126 (5) ◽  
pp. 404-409 ◽  
Author(s):  
CG Semple ◽  
R Mitchell ◽  
S Hollis ◽  
WR Robertson
Keyword(s):  
Biological Activity ◽  
Serum Testosterone ◽  
Normal Subjects ◽  
Published Data ◽  
Blood Samples ◽  
Testosterone Concentration ◽  
Lh Pulsatility ◽  
Pulse Peak ◽  
The Mean ◽  
Normal Men

LH pulsatility studies were performed in six burned patients by removing blood samples at 10 min intervals over a 6 h period. All samples were assayed for LH by bioassay (B-LH), LH by radioimmunoassay (I-LH) and testosterone. Mean serum testosterone concentrations of the burned patients were low (6.7±1.6 nmol/l). I-LH levels were lower than B-LH in all samples. Frequency of bioactive or immunoreactive pulses as well as mean B-LH and I-LH concentrations were similar to previously published data from normal men examined in the same laboratory. The mean biological activity of LH (expressed as the ratio of B-LH to I-LH, the B:I ratio) was lower in burned subjects (1.9±0.1) than previously reported in normal men. The B:I ratios of burned men were lower (p <0.01) at pulse peaks than at nadirs (1.8±0.1 vs 2.0±0.1) and an increase in serum testosterone concentration did not follow an LH peak. Serum testosterone concentrations did not cross-correlate with B-LH or I-LH. This contrasts with the findings in normal subjects where the B:I ratios have been found to be higher at pulse peaks than at nadirs and an increase in serum testosterone concentration follows a pulse peak and serum testosterone cross-correlates with B-LH and I-LH. LH secreted in a pulse peak in normal men may contain a particularly biologically potent form of the molecule but this may not be the case in burned men.

Effects of acute stimulation with luteinizing hormone-releasing hormone (LRH) on biologically active and immunoreactive serum luteinizing hormone (LH) in pubertal boys

1984 ◽  
Vol 107 (3) ◽  
pp. 289-294 ◽  
Author(s):  
Vanna Montanini ◽  
Marco Francesco Celani ◽  
Gian Franco Baraghini ◽  
Cesare Carani ◽  
Paolo Marrama
Keyword(s):  
Luteinizing Hormone ◽  
Serum Levels ◽  
Biologically Active ◽  
Acute Administration ◽  
Adult Men ◽  
Serum Luteinizing Hormone ◽  
Significant Difference ◽  
The Mean ◽  
Pubertal Boys

Abstract. The responses of biologically active LH (BIO-LH) and immunoreactive LH (RIA-LH) to acute stimulation with LRH (0.1 mg iv) were studied in 8 pubertal boys (9–15 years, 2nd–4th Tanner's stage), and in 10 healthy adult men (20–46 years). Serum levels of BIO-LH were assessed by an in vitro bioassay method based upon testosterone production by mechanically dispersed mouse Leydig cell preparations. In pubertal boys the mean BIO-LH/RIA-LH (B/I) ratio of basally secreted LH was significantly lower than in adult men (1.2 ± 0.2 (sem) and 2.2 ± 0.2 respectively, P < 0.01). After acute administration of LRH the mean B/I ratio of circulating LH showed a significant increase from the basal value in pubertal boys (2.6 ± 0.2, P < 0.01 vs basal values), whereas no significant difference in LH B/I ratios were demonstrated throughout the study period in adult men (2.1 ± 0.1, P = NS vs basal values). In agreement with this finding, the mean relative maximum response for BIO-LH (BIO-LH Δ%) was higher in pubertal boys than in adult men (1702.7 ± 500.3 and 499.6 ± 65.4% respectively, P < 0.05), whereas the mean RIA-LH Δ% was similar in both groups (609.1 ± 85.1 and 534.1 ± 75.5% respectively, P = NS). No significant differences were shown in the BIO-LH Δ area between pubertal boys (4.9 ± 0.9 area units × 103) and adult men (6.7 ± 1.2 area units × 103, P = NS), whereas the mean RIA-LH Δ area was significantly lower in the former group (1.9 ± 0.4 area units × 103 vs 3.2 ± 0.5 area units × 103, P < 0.05). Our study emphasizes that the pubertal pituitary possesses a greater responsiveness for BIO-LH than the adult pituitary, and that in pubertal boys acute stimulation with LRH evokes the release of a more bioactive form of LH.

Episodic nyctohemeral secretion of melatonin in adult humans: Lack of relation with LH pulsatile pattern

1990 ◽  
Vol 122 (1) ◽  
pp. 76-82 ◽  
Author(s):  
Alberto de Leiva ◽  
Federico Tortosa ◽  
Miguel A. Peinado ◽  
José Serrano ◽  
José Rodriguez-Espinosa ◽  
...  
Keyword(s):  
Mean Amplitude ◽  
Melatonin Secretion ◽  
Melatonin Concentration ◽  
Significant Difference ◽  
Adult Humans ◽  
Early Follicular Phase ◽  
The Mean ◽  
Normal Women ◽  
Normal Men ◽  
Lh Secretion

Abstract The concentration of melatonin and LH were determined in plasma samples obtained at 10-min intervals during 4 h of darkness (00.00-04.00 h) from 4 normal women, age 23-27 years, in the early follicular phase of the menstrual cycle and in 6 normal men, age 23-31 years. Additionally, melatonin concentration was determined in samples obtained from the men at 10-min intervals for 4 h during the day (10.00-14.00 h). A pulsatile pattern of melatonin secretion was found for all the subjects during darkness. There was no significant difference between women and men as to the number of pulses (2.8 ± 0.5 vs 5.2 ± 1.0 per 4 h), amplitude of pulses (51.3 ± 28 vs 27.2 ± 6 ng/l), concentration per 4 h (32.5 ± 13 vs 31.0 ± 5 ng/l), or apparent half-life of melatonin (19.3 ± 2.3 vs 15.3 ± 7.5 min). The mean amplitude of the melatonin pulse correlated (r = 0.863, p<0.001) with the mean melatonin concentration per 4 h. A pulsatile LH secretion pattern was found for the 10 subjects and did not correlate significantly with the melatonin secretion pattern. The results are consistent with an independent signal for the demonstrated nyctohemeral pulsatile melatonin and LH secretions.

Interpulse interval of GnRH stimulation independently modulates LH secretion

1989 ◽  
Vol 256 (4) ◽  
pp. E510-E515
Author(s):  
L. S. O'Dea ◽  
J. S. Finkelstein ◽  
D. A. Schoenfeld ◽  
J. P. Butler ◽  
W. F. Crowley
Keyword(s):  
Positive Relationship ◽  
Important Determinant ◽  
Pulse Amplitude ◽  
Gonadotropin Releasing Hormone ◽  
Interpulse Interval ◽  
The Mean ◽  
Normal Men ◽  
Low Amplitude ◽  
Lh Secretion ◽  
Independent Determinant

To examine the importance of the interpulse interval of gonadotropin-releasing hormone (GnRH) stimulation in modulating gonadotroph responsiveness, a fixed individualized dose of GnRH was administered to eight GnRH-deficient men at intervals selected randomly from the distribution of luteinizing hormone (LH) interpulse intervals of normal men. The responses were compared with data derived from a study of LH pulses in 20 normal men. A positive relationship was found between LH pulse amplitude and the preceding interpulse interval both in the GnRH-deficient (P less than 0.05) and in the normal (P less than 0.003) men. The distributions of LH pulse amplitudes appeared to differ between the two groups with failure of the study paradigm to reproduce the distribution of low-amplitude pulses of the normal men in the GnRH-deficient men. There was significantly more variability about the line that related interpulse interval and LH amplitude in the normal men (P less than 0.004) in whom the amount of GnRH could vary physiologically. This difference remained significant both for pulses with amplitudes below (P less than 0.01) or above (P less than 0.03) the mean of the normal men. These studies demonstrate that the GnRH interpulse interval is an independent determinant of pituitary responsiveness and that alterations in the amount of GnRH secreted from the hypothalamus are an important determinant of LH pulse amplitude in men.

Changes in the bioactivity to immunoreactivity ratio of circulating luteinizing hormone in impotent men treated with testosterone undecanoate

1989 ◽  
Vol 120 (3) ◽  
pp. 284-288 ◽  
Author(s):  
C. Carani ◽  
M. F. Celani ◽  
D. Zini ◽  
A. Baldini ◽  
L. Della Casa ◽  
...  
Keyword(s):  
Leydig Cell ◽  
Serum Levels ◽  
Mean Value ◽  
Serum Concentrations ◽  
Placebo Administration ◽  
In Vitro Bioassay ◽  
Testosterone Undecanoate ◽  
The Mean ◽  
Mouse Leydig Cell

Abstract. Testosterone undecanoate was administered orally (80 mg twice daily) for 30 days to 10 impotent men with mild Leydig cell failure, age 28 to 42 years. Placebo was administered for 30 days both before and at the end of testosterone undecanoate therapy. Serum levels of bioactive LH, immunoreactive LH and testosterone were determined in basal conditions (day zero), 30 days after the first placebo administration, at the 15th and 30th day of testosterone undecanoate therapy, and at the end of the second treatment with placebo (90th day). Bioactive LH was measured by a sensitive and specific in vitro bioassay based on testosterone production by mechanically dispersed mouse Leydig cell preparations. Immunoreactive LH and testosterone were determined by a doubleantibody RIA technique. The results were compared with those obtained in 30 untreated normal young men. In the basal state, serum concentrations of immunoreactive LH were significantly higher in the patients (P< 0.02) than in control subjects, whereas testosterone levels were significantly lower (P< 0.001) in the impotent men. In contrast, bioactive LH levels and the bioactive LH to immunoreactive LH ratios were similar in the two groups. In the patients, at the 15th day of treatment with testosterone undecanoate, serum levels of testosterone and bioactive LH were significantly higher (P< 0.01) than basal values, whereas immunoreactive LH concentrations showed no significant changes. Consequently, the bioactive LH to immunoreactive LH ratios rose significantly (P< 0.01). At the 30th day of treatment with testosterone undecanoate, the mean value of bioactive LH and the mean bioactive LH to immunoreactive LH ratio were significantly higher (P< 0.01) in the patients than in control men, whereas the mean levels of testosterone and immunoreactive LH were similar in the two groups. Neither the first nor the second treatment with placebo changed the hormone values observed in basal conditions. The results support the experimental evidence that androgens may increase the bioactivity of circulating LH.

Speed of low-frequency sound through lungs of normal men

1983 ◽  
Vol 55 (6) ◽  
pp. 1862-1867 ◽  
Author(s):  
S. S. Kraman
Keyword(s):  
Chest Wall ◽  
Speed Of Sound ◽  
Sulfur Hexafluoride ◽  
Low Frequency ◽  
Lung Parenchyma ◽  
Cross Correlation Analysis ◽  
The Mean ◽  
Normal Men

The speed of propagation of vesicular lung sound through the lung has not been clearly established. In a recent study (J. Appl. Physiol.: Respirat. Environ. Exercise Physiol. 54: 304-308, 1983), Rice measured the speed of sound through the parenchyma of excised horse lungs and found it to be 25-70 m/s (less than 20% the speed of sound in air). Filling the lung with helium or sulfur hexafluoride changed the speed of transmission by less than 10%, indicating nongas propagation. The present study was designed to measure the speed of sound through human lungs in vivo. Five healthy, nonsmoking males (aged 27-38 yr) were studied. A microphone was placed on the neck beneath the larynx and another at each of eight locations on the chest wall. Measurements were made at functional residual capacity. White noise was band-pass filtered between 125 and 500 Hz, amplified, and delivered to a loudspeaker connected to a mouthpiece. The speed of sound was measured by cross-correlation analysis of the signals simultaneously detected by the tracheal and chest microphones. This was done after breathing both air and a mixture of 80% He in 20% O2 (He-O2). With air, the mean sound-transit time (trachea to chest wall) ranged from 2 ms at the upper chest to 5 ms at the lower chest (speed of approximately 30 m/s). With He-O2 the mean speed increased by only 10%, whereas the predicted increase of sound speed through gas alone would be greater than 100%. These results are consistent with the in vitro findings of Rice and suggest that within the frequency range of vesicular lung sounds transmission of sound introduced at the mouth is predominantly through the lung parenchyma, not through the airways.

Effects of naloxone on catecholamine plasma levels in adult men. A dose-response study

1984 ◽  
Vol 106 (3) ◽  
pp. 357-361 ◽  
Author(s):  
Massimo Mannelli ◽  
Mario Maggi ◽  
Maria Laura De Feo ◽  
Silvana Cuomo ◽  
Giuseppe Delitala ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Plasma Levels ◽  
Plasma Insulin ◽  
Endogenous Opiates ◽  
Adult Men ◽  
Before And After ◽  
Normal Men ◽  
Dose Response Study

Abstract. To evaluate a possible role for endogenous opiates in modulating sympathetic-adrenal function in humans, we measured plasma epinephrine and norepinephrine (radioenzymatic method), blood pressure and heart rate in 8 normal men (aged 24–33 years) before and after placebo or different doses (0.4, 4.8, 10 mg) of naloxone. In 6 subjects plasma insulin and glucagon levels were also measured by radioimmunoassay after placebo and 10 mg naloxone. Naloxone had no significant effect upon blood pressure, heart rate, plasma insulin, glucagon or norepinephrine. Placebo, 0.4 and 4.8 mg naloxone caused no significant change in peripheral levels of epinephrine while 10 mg produced an increase in epinephrine concentrations 15 min after iv injection (186 ± 23 vs 99 ± 9 pmol/l, P < 0.01). Since naloxone did not modify plasma levels of insulin and glucagon, an indirect effect of naloxone on adrenal medullary secretion seems to be excluded. These results are in agreement with in vitro experimental data obtained in animals and suggest that endogenous opiates also have a role in modulating adrenal medullary secretion in man.

AN ASSAY FOR PLASMA SOMATOMEDIN: [3H]THYMIDINE INCORPORATION BY ISOLATED RABBIT CHONDROCYTES

1977 ◽  
Vol 74 (2) ◽  
pp. 205-212 ◽  
Author(s):  
I. K. ASHTON ◽  
M. J. O. FRANCIS
Keyword(s):  
Growth Hormone ◽  
Direct Effect ◽  
Thymidine Incorporation ◽  
Human Growth ◽  
Bovine Growth Hormone ◽  
Sensitive Assay ◽  
Adult Men ◽  
Normal Plasma ◽  
The Mean

The incorporation of [3H]thymidine by rabbit chondrocytes in vitro has been developed as a sensitive assay for plasma somatomedin. A concentration of normal plasma of 2·5% enhanced [3H]thymidine incorporation by 5- to 20-fold compared with basal levels in the absence of plasma. The mean potency of plasma from normal adult men was 0·96 ± 0·1 u./ml (mean ± s.d.) and from acromegalic patients 1·9 ± 0·4 u./ml. The apparent potency of hypopituitary plasma alone increased on heating which suggested the presence of heatlabile inhibitors of somatomedin activity. The potency of heated hypopituitary plasma (0·6 ± 0·09 u./ml) remained significantly lower (P < 0·01) than normal plasma. Human growth hormone (0·1–20 μu./ml), bovine growth hormone (0·5–20 μu./ml), insulin (0·5–5 μu./ml) and glucose (0·3–2 mmol/l) had no direct effect on the incorporation of [3H]thymidine. Chondrocytes which had been previously stored frozen also showed a response to plasma somatomedin.

scholarly journals IN VITRO FERTILIZATION

2016 ◽  
Vol 23 (09) ◽  
pp. 1138-1144
Author(s):  
Haroon Latif Khan ◽  
Yousaf Latif Khan ◽  
Rameen Makhdoom ◽  
Abdul Rahman Khawaja
Keyword(s):  
Ovarian Reserve ◽  
Transvaginal Ultrasound ◽  
Follicular Phase ◽  
Clinical Pregnancy ◽  
Blood Samples ◽  
Vitro Fertilization ◽  
Early Follicular Phase ◽  
The Mean ◽  
Relationship Of

Various ovarian reserve tests were developed to estimate the ovarian reserve andpredict about the outcome in subfertile females undergoing evaluation for assisted reproduction.FSH and AMH levels are considered to be good ovarian reserve indicators along with antralfollicle count. Objectives: To explore relationship of AMH and FSH in patients undergoing IVFwith respect to ovarian reserve and outcome of the treatment. Study Design: Prospective cohort.Study Period: 1st January 2015 to 31st December 2015. Place of study: Lahore Institute ofFertility and Endocrinology, Hameed Latif Hospital, Lahore Material and Methods: In 346 IVF/ICSI patients after anthropometric measurements and transvaginal ultrasound antral folliclecount were assessed in each ovary. For the hormone measurements blood samples were takenduring the early follicular phase of menstrual cycle. Clinical pregnancy was also visualizedthrough transvaginal ultrasound. Results: From the 346 IVF/ICSI patients 89 (25.79%) clinicalpregnancies resulted. The mean age in pregnant group was 32.89 ± 2.99 years and in nonpregnantgroup was 33.62 ±4.36. Mean FSH and AMH in pregnant group was 6.38 ±2.38,3.27 ±1.86 and in non- pregnant group was 7.54±3.76, 2.72 ± 1.82 respectively. Age andFSH are significantly associated with each other (p-vale = 0.000) and mostly patients had FSHbelow 9(mIU/mL). Age and AMH are significantly associated with each other (p-vale = 0.000)and mostly patients had AMH above 1.5 (ng/mL). Conclusions: Better pregnancy rate wasassociated with FSH below than 9 (mIU/mL) and AMH above 1.5 (ng/mL).

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