Impact of pulsatility on the ensemble orderliness (approximate entropy) of neurohormone secretion

2001 ◽  
Vol 281 (6) ◽  
pp. R1975-R1985 ◽  
Author(s):  
J. D. Veldhuis ◽  
M. L. Johnson ◽  
O. L. Veldhuis ◽  
M. Straume ◽  
S. M. Pincus
Keyword(s):  
Half Life ◽  
Young Male ◽  
Approximate Entropy ◽  
Pulse Amplitude ◽  
Interval Length ◽  
Normal Female ◽  
Pulse Trains ◽  
Burst Amplitude ◽  
The Impact ◽  
Lh Secretion

Regular patterns of neurohormone secretion are driven by underlying pulsatile and subordinate (feedback sensitive) dynamics. Measures of time-series orderliness, e.g., the approximate entropy (ApEn) statistic (Pincus SM. Proc Natl Acad Sci 88: 2297–2301, 1991), vividly discriminate pathological and physiological patterns of hormone release. To investigate how specific pulsatility features impact regularity estimates, we have examined the sensitivity of the ApEn metric to systematic variations in the frequency, amplitude, and half-life of simulated neurohormone pulse trains (Veldhuis JD, Carlson ML, and Johnson ML. Proc Natl Acad Sci 84: 7686–7690, 1987) and compared the impact of a high vs. low baseline luteinizing hormone (LH) pattern regularity state mimicking the normal female luteal phase and the young male, respectively. Shortening the interpulse interval length elevated ApEn in both pulsatility models, thereby signifying greater ensemble series irregularity. The frequency sensitivity of ApEn was robust to several complementary renditions of ApEn and to variations in experimental uncertainty, basal (nonpulsatile) LH secretion, and secretory burst amplitude. ApEn rose with increasing hormone half-life, especially in the face of low baseline variability emulated by midluteal LH secretion profiles. High variability of secretory burst amplitude, pulse duration, or interpeak intervals increased ApEn in the more orderly femalelike construct; in the highly irregular malelike LH pulse model, these variability changes had little effect on ApEn. In summary, the ensemble regularity statistic, ApEn, quantifies unequal pattern orderliness in neurohormone pulse trains with minimal dependence on mean pulse amplitude, interpulse baseline, or (subthreshold) sample uncertainty. Thus ApEn monitors changing secretory event frequency and interpulse variability with sensitivity to starting pattern regularity, providing a mechanistic linkage between model evolution and statistical change.

Evaluation of LH secretory dynamics during the rat proestrous LH surge

1999 ◽  
Vol 276 (1) ◽  
pp. R219-R225 ◽  
Author(s):  
Kathleen M. Hoeger ◽  
Lisa A. Kolp ◽  
Frank J. Strobl ◽  
Johannes D. Veldhuis
Keyword(s):  
Half Life ◽  
Approximate Entropy ◽  
Fold Increase ◽  
Pituitary Hormones ◽  
Release Process ◽  
Secretory Rate ◽  
Lh Surge ◽  
Concentration Time Series ◽  
Lh Release ◽  
Lh Secretion

The preovulatory luteinizing hormone (LH) surge results from the integration of complex interactions among gonadal steroids and hypothalamic and pituitary hormones. To evaluate changes in LH secretory dynamics that occur during the rat LH surge, we have 1) obtained frequently sampled serum LH concentration time series, 2) used both waveform-dependent and waveform-independent convolution analyses, and 3) independently assessed proestrous LH half-life and basal non-gonadotropin-releasing hormone (GnRH)-dependent LH secretion during the LH surge. Waveform-independent pulse analysis revealed a 24-fold increase in the maximal pulsatile LH secretory rate attained during late proestrus compared with early proestrus. A 15-fold increase was quantified for the mean LH secretory rate. In complementary analyses, we applied a measured LH half-life of 17 ± 2.7 min and a median basal LH secretion rate of 0.0046 μg ⋅ l−1 ⋅ min−1 for convolution analysis, revealing a 16-fold increase in the mass of LH released/burst and more than sixfold rise in the amplitude of the secretory peaks. Evaluation of the approximate entropy of the LH surge profiles was performed, showing an increase in the orderliness of the LH release process during the surge. We conclude that both quantitative (mass/burst) and qualitative (approximate entropy) features of LH release are regulated during the proestrous LH surge.

scholarly journals Analysis of the impact of intravenous LH pulses versus continuous LH infusion on testosterone secretion during GnRH-receptor blockade

2012 ◽  
Vol 303 (10) ◽  
pp. R994-R1002 ◽  
Author(s):  
Johannes D. Veldhuis ◽  
Peter Y. Liu ◽  
Paul Y. Takahashi ◽  
Suanne M. Weist ◽  
Jean R. Wigham
Keyword(s):  
Rank Order ◽  
Approximate Entropy ◽  
Target Tissue ◽  
Deconvolution Analysis ◽  
Lh Pulsatility ◽  
Tissue Responses ◽  
Gonadotrophin Releasing Hormone ◽  
The Mean ◽  
The Impact ◽  
Lh Secretion

Gonadotrophin-releasing hormone (GnRH) pulsatility is required for optimal luteinizing hormone (LH) secretion, but whether LH pulsatility is required for physiological testosterone (T) secretion is not known. To test the postulate that pulses of recombinant human (rh) LH stimulate greater T secretion than continuous infusion of the same dose, a potent selective GnRH antagonist was administered overnight to 19 healthy men ages 18–49 yr. Subjects then received saline or rhLH intravenously continuously or as 6-min pulses intravenously every 1 or 2 h at the same total dose. Blood was sampled every 10 min for 10 h to quantify T responses. For the four interventions, the descending rank order of mean LH and mean T concentrations was 1-h = 2-h rhLH pulses > continuous rhLH > saline ( P < 10−3). Plateau LH and T concentrations correlated positively ( R2 = 0.943, P = 0.029) as did LH concentrations and LH half-lives ( R2 = 0.962, P = 0.019). Percentage pulsatile T secretion assessed by deconvolution analysis (Keenan DM, Takahashi PY, Liu PY, Roebuck PD, Nehra AX, Iranmanesh A, Veldhuis JD. Endocrinology 147: 2817–2828, 2006) was the highest ( P = 0.019), and half-time to attain peak T concentrations was the shortest ( P < 10−6), for 1-h rhLH pulses. Approximate entropy (a pattern-regularity measure) revealed more orderly T secretion for 1- than 2-h rhLH pulses ( P = 0.0076). Accordingly, a pulsatile LH signal, while not obligatory to maintain mean T concentrations, controls the mean plasma LH concentration and determines quantifiable patterns of T secretion. These data introduce the question whether blood T patterns in turn supervise distinctive target-tissue responses.

Reanalysis of the rat proestrous LH surge by deconvolution analysis

1993 ◽  
Vol 265 (1) ◽  
pp. R240-R245
Author(s):  
J. D. Veldhuis ◽  
M. L. Johnson ◽  
R. V. Gallo
Keyword(s):  
Luteinizing Hormone ◽  
Half Life ◽  
Fold Increase ◽  
Basal Secretion ◽  
Release Rates ◽  
Deconvolution Analysis ◽  
Lh Surge ◽  
Time Profiles ◽  
Burst Amplitude ◽  
Lh Secretion

To evaluate the temporal mechanisms that give rise to the spontaneous proestrous surge of luteinizing hormone (LH) in the rat, we have applied deconvolution analysis to earlier immunoreactive LH concentration vs. time profiles obtained by sampling blood in proestrus at 2- to 3-min intervals in 10 animals over a span of 160-300 min. Six other animals were bled in 6-min intervals on day 1 of diestrus. Deconvolution analysis permitted us to calculate the number, duration, amplitude (maximal release rates), and mass of underlying LH secretory bursts and to simultaneously estimate basal secretion and the half-life of endogenous LH in each animal. Proestrus rats exhibited a significant increase in the number of computer-identified LH secretory bursts per hour (1.8 +/- 0.2 vs. 1.1 +/- 0.01 on diestrus, P < 0.01), with a corresponding reduction in the LH intersecretory burst interval from 61 +/- 6.4 min (diestrus) to 25 +/- 2.7 min (proestrus, P < 0.01). There was a remarkable 16-fold increase in the mass of LH secreted per burst, which rose from 72 +/- 5.2 to 1,230 +/- 200 ng/ml (P < 0.01). This resulted from a sixfold increase in LH secretory burst amplitude and a doubling of burst duration. The total amount of LH released in a burstlike fashion during the proestrous LH surge rose 20-fold, and calculated basal LH secretion increased to approximately 25% of this value. Of interest, the computed half-life of endogenous LH also increased from 10 +/- 1.1 to 19 +/- 3.7 min (P < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

scholarly journals Inhibition of the secretion of LH in ovariectomised pigs by sustained but not repeated acute elevation of cortisol in the absence but not the presence of oestradiol

1999 ◽  
Vol 163 (3) ◽  
pp. 477-486 ◽  
Author(s):  
AI Turner ◽  
PH Hemsworth ◽  
BJ Canny ◽  
AJ Tilbrook
Keyword(s):  
Acute Stress ◽  
Plasma Concentrations ◽  
Pulse Amplitude ◽  
Follicular Phase ◽  
Elevated Plasma ◽  
Acute Elevation ◽  
The Mean ◽  
The Impact ◽  
Lh Secretion ◽  
Prolonged Stress

Prolonged stress is known to impair reproduction. It has been proposed that reproduction will also be impaired when a severe acute stress occurs during a period of elevated plasma concentrations of oestradiol, such as during the follicular phase of the oestrous cycle. In this experiment, we hypothesised that repeated acute and sustained elevation of cortisol would suppress the secretion of LH in ovariectomised pigs and that these effects would be enhanced in the presence of oestradiol negative feedback. Cortisol (or vehicle) was administered 12 hourly to ovariectomised pigs (n=6/treatment) for 8 days in the absence of oestradiol treatment and for a further 8 days during treatment with oestradiol. Vehicle was administered to 'control' pigs, 10 or 20 mg cortisol was administered i.v. to pigs to produce 'repeated acute' elevation of cortisol and 250 mg cortisol was administered i.m. to pigs to give a 'sustained' elevation of cortisol. Both before and during treatment with oestradiol, plasma concentrations of LH were monitored on the day before treatment, on the 4th and 8th days of treatment and following an i.v. injection of GnRH at the end of the 8th day of treatment. The repeated acute elevation of cortisol did not impair any parameters of LH secretion (i.e. mean plasma concentrations of LH, pulse amplitude or frequency, pre-LH pulse nadir or the LH response to GnRH) in the absence or in the presence of oestradiol. In contrast, when the elevation of cortisol was sustained, the mean plasma concentrations of LH and the pre-LH pulse nadir were significantly (P<0.05) lower on the 8th day of treatment than on the day before treatment and on the 4th day of treatment. Nevertheless, no other parameters of LH secretion were affected and these effects only occurred in the absence (not in the presence) of oestradiol. In conclusion, cortisol needed to be elevated for more than 4 days to impair the secretion of LH, and oestradiol did not enhance the impact of cortisol on LH secretion in ovariectomised pigs.

Luteinizing hormone secretory pattern before and after removal of Leydig cell tumor of the testis

1994 ◽  
Vol 131 (2) ◽  
pp. 156-159 ◽  
Author(s):  
Philippe J Caron ◽  
Antoine P Bennet ◽  
Monique M Plantavid ◽  
Jean-Pierre Louvet
Keyword(s):  
Luteinizing Hormone ◽  
Leydig Cell ◽  
Half Life ◽  
Pulse Amplitude ◽  
Leydig Cell Tumor ◽  
Cell Tumor ◽  
Pulse Interval ◽  
Before And After ◽  
Lh Secretion ◽  
Secretory Pattern

Caron PJ, Bennet AP, Plantavid MM, Louvet J-P. Luteinizing hormone secretory pattern before and after removal of Leydig cell tumor of the testis. Eur J Endocrinol 1994;131:156–9. ISSN 0804–4643 We studied the luteinizing hormone (LH) secretory pattern in three patients, aged 30, 23 and 43 years, with gynecomastia due to Leydig cell tumor of the testis, before and 6 months after unilateral orchidectomy. The results were compared to those of 11 normal fertile controls aged 20–35 years. Blood sampling was done at 20-min intervals from 22.00 h to 10.00 h. The LH data were analyzed with the Cluster analysis algorithm with "optimal parameters for LH male data" to determine the pulse interval and pulse amplitude. The Expfit program was applied to LH pulses to calculate the apparent half-life of immunoreactive LH. Before surgery, when compared to controls, the patients had a low to normal testosterone/estradiol ratio (0.053, 0.110, 0.046 vs 0.148 ± 0.038) and mean LH levels (1.96, 3.7, 2.55 vs 4.0 ± 1.9 IU/l), decreased pulse amplitude (2.65, 3.01, 2.21 vs 3.31 ± 1.41 IU/l) and reduced apparent half-life of LH (74, 69, 78 vs 97 ± 16 min). After removal of the Leydig cell tumor, the testosterone/estradiol ratio returned to the normal range (0.141, 0.177, 0.093) while an increase in mean LH levels (5.75, 7.90, 4.88 IU/l), LH pulse amplitude (3.07, 6.05, 2.86 IU/l) and apparent half-life of LH (138, 106, 104 min) was observed in all three patients. Our data indicate that endogenous hyperestrogenism in patients with Leydig cell tumor of the testis results in an inhibition of LH secretion, and suggests that such inhibition could result from a reduction in pulse amplitude and apparent half-life. Philippe Caron, Service d'Endocrinologie et Maladies métaboliques, CHU Rangueil, 1 Avenue J Poulhes, 31054 Toulouse Cedex, France

scholarly journals Advertising Media Impact in Consumer Buying Behavior

2019 ◽  
Vol 8 ◽  
pp. 54-56
Author(s):  
Ashmita Dahal Chhetri
Keyword(s):  
Consumer Behavior ◽  
Young Male ◽  
Electronic Media ◽  
Buying Behavior ◽  
Media Impact ◽  
High Degree ◽  
The Impact ◽  
Buying Behaviors ◽  
The Relationship ◽  
Better Than

Advertisements have been used for many years to influence the buying behaviors of the consumers. Advertisements are helpful in creating the awareness and perception among the customers of a product. This particular research was conducted on the 100 young male and female who use different brands of product to check the influence of advertisement on their buying behavior while creating the awareness and building the perceptions. Correlation, regression and other statistical tools were used to identify the relationship between these variables. The results revealed that the relationship between media and consumer behavior is positive. The adve1tising impact on sales and there is positive and high degree relationship between advertising and consumer behavior. The impact on advertising of a product of electronic media is better than non-electronic media.

scholarly journals Short-Term High Fat Intake Does Not Significantly Alter Markers of Renal Function or Inflammation in Young Male Sprague-Dawley Rats

2015 ◽  
Vol 2015 ◽  
pp. 1-9 ◽  
Author(s):  
Catherine Crinigan ◽  
Matthew Calhoun ◽  
Karen L. Sweazea
Keyword(s):  
Kidney Disease ◽  
Renal Mass ◽  
Early Stage ◽  
Young Male ◽  
Protective Effects ◽  
Sprague Dawley ◽  
High Fat ◽  
Short Term ◽  
Sprague Dawley Rats ◽  
The Impact

Chronic high fat feeding is correlated with diabetes and kidney disease. However, the impact of short-term high fat diets (HFD) is not well-understood. Six weeks of HFD result in indices of metabolic syndrome (increased adiposity, hyperglycemia, hyperinsulinemia, hyperlipidemia, hyperleptinemia, and impaired endothelium-dependent vasodilation) compared to rats fed on standard chow. The hypothesis was that short-term HFD would induce early signs of renal disease. Young male Sprague-Dawley rats were fed either HFD (60% fat) or standard chow (5% fat) for six weeks. Morphology was determined by measuring changes in renal mass and microstructure. Kidney function was measured by analyzing urinary protein, creatinine, and hydrogen peroxide (H2O2) concentrations, as well as plasma cystatin C concentrations. Renal damage was measured through assessment of urinary oxDNA/RNA concentrations as well as renal lipid peroxidation, tumor necrosis factor alpha (TNFα), and interleukin 6 (IL-6). Despite HFD significantly increasing adiposity and renal mass, there was no evidence of early stage kidney disease as measured by changes in urinary and plasma biomarkers as well as histology. These findings suggest that moderate hyperglycemia and inflammation produced by short-term HFD are not sufficient to damage kidneys or that the ketogenic HFD may have protective effects within the kidneys.

Pulsatile LH secretion in streptozotocin-induced diabetes in the rat

1991 ◽  
Vol 131 (1) ◽  
pp. 49-55 ◽  
Author(s):  
Q. Dong ◽  
R. M. Lazarus ◽  
L. S. Wong ◽  
M. Vellios ◽  
D. J. Handelsman
Keyword(s):  
Weight Loss ◽  
Insulin Treatment ◽  
Pulse Generator ◽  
Latin Square ◽  
Pulse Amplitude ◽  
Pulse Frequency ◽  
Metabolic Effect ◽  
Male Rat ◽  
Free Access ◽  
Lh Secretion

ABSTRACT This study aimed to determine the effect of streptozotocin (STZ)-induced diabetes on pulsatile LH secretion in the mature male rat. LH pulse frequency was reduced by 56% and pulse amplitude by 54%, with a consequential decrease of 72% in mean LH levels 8 days after i.v. administration of STZ (55 mg/kg) to castrated Wistar rats compared with castrated non-diabetic controls. Twice daily insulin treatment completely reversed all parameters of pulsatile LH secretion to control values. Food-restricted non-diabetic controls, studied to distinguish the metabolic effect of diabetes from that of concurrent weight loss, demonstrated a 34% reduction in LH pulse frequency but no significant changes in LH pulse amplitude or mean LH levels compared with non-diabetic controls given free access to food. To distinguish whether the decreased LH pulse amplitude in diabetes was due to a reduction in either the quantity of hypothalamic gonadotrophin-releasing hormone (GnRH) released per secretory episode or to decreased pituitary responsiveness to GnRH, the responsiveness of the pituitary to exogenous GnRH (1–1000 ng/kg body weight) was tested in diabetic rats after castration, using a full Latin square experimental design. The net LH response (total area under response curve over 40 min following GnRH) was decreased by 33% (P=0·001) in diabetic compared with control rats. The decreased LH pulse frequency in STZ-induced diabetes therefore suggests that the metabolic effect of diabetes is to decelerate directly the firing rate of the hypothalamic GnRH pulse generator independent of testicular feed-back. These effects were fully reversed by insulin treatment and were only partly due to the associated weight loss. The impaired pituitary responsiveness to GnRH is at least partly involved in the reduction of LH pulse amplitude. Journal of Endocrinology (1991) 131, 49–55

Editorial

2012 ◽  
Vol 11 (1) ◽  
Author(s):  
Chris Roseveare ◽  
Keyword(s):  
Patient Safety ◽  
Young Male ◽  
Final Diagnosis ◽  
Mass Casualty ◽  
Major Incident ◽  
Spare Capacity ◽  
Acute Medical Unit ◽  
Infected Urine ◽  
Temporary Closure ◽  
The Impact

The snow and freezing temperatures will hopefully have passed by the time this edition reaches you; the sight of daffodils may be asignal that the relief of spring is not far off. Winter frequently stretches AMU resources to the limit – in recent years we have had epidemics of seasonal and swine f lu, but this year Norovirus seems to have been the bigger challenge. Ward closures from diarrhoea outbreaks have traditionally been more of a ‘downstream’ problem (no pun intended), but the impact of closure of the AMU would be substantial.At the time of writing this has still, thankfully, been avoided in my own hospital; however it remains a circumstance for which we have to be prepared. This edition’s ‘Viewpoint’ article describes how temporary closure of the AMU was managed in a London hospital. The use of an empty ‘winter pressures ward’ eased the burden in this case, enabling the AMU service to be maintained. Even with the luxury of this spare capacity, there was clearly significant disruption, requiring close collaboration between a variety of departments, which is well described by the authors. Many hospitals have become highly dependent on a functioning AMU to provide timely, safe and effective care for medical emergencies. Major incident plans are in place to deal with mass casualty incidents; we need to consider similar contingencies to deal with AMU closure if patient safety is going to be maintained. This article is a timely reminder of the need for forward planning. Maintaining patient safety is a mantra which will be familiar to acute physicians, particularly those who attended any of the recent SAM meetings, where this theme has been well rehearsed. An acute medical unit can provide significant safety benefits by concentrating resources in a single area. However, for the 60% who cannot go directly home from the AMU, this model creates the need for care to be transferred at some point. It is well recognised that transfer is a time at which patient safety can become compromised; so if safety is our mantra, acute physicians and nurses have a responsibility to manage this process effectively. The article by David Hindmash and Liz Lees provides an important addition to the limited literature in this area. Structured checklists are becoming an increasing part of medical practice; this paper highlights how a checklist can be used to improve the quality of handover from AMU. The authors emphasise the need to keep the form simple, and the importance of regular reinforcement to ensure that it is used. What skills and attributes does an acute physician require? With interview season approaching it’s a question that many prospective trainees will be contemplating – remaining calm under pressure, communication skills and teamworking are some of the standard responses; but what about a good sense of smell? Most of us recognise the characteristic odour of melaena , or the whiff of infected urine. But the absence of body odour might be equally revealing. Luther and Yap noted their patient to be ‘remarkably clean’ – unusual, perhaps, for a young male patient on the AMU; along with his persistent demands to use the showering facilities, this was a clue to the final diagnosis of Cannabis Hyperemesis Syndrome.It’s a case worth reading and highlights the importance of lateral thinking, particularly when patients repeatedly attend – as well as having a ‘good nose’ to sniff out something unusual!

scholarly journals A psychrometric model to assess the biological decay of the SARS-CoV-2 virus in aerosols

PeerJ ◽  
2021 ◽  
Vol 9 ◽  
pp. e11024
Author(s):  
Clive B. Beggs ◽  
Eldad J. Avital
Keyword(s):  
Air Temperature ◽  
Vapour Pressure ◽  
Half Life ◽  
Analytical Study ◽  
Decay Constant ◽  
Meteorological Data ◽  
Environmental Parameters ◽  
Published Data ◽  
Reasonable Accuracy ◽  
The Impact

There is increasing evidence that the 2020 COVID-19 pandemic has been influenced by variations in air temperature and humidity. However, the impact that these environmental parameters have on survival of the SARS-CoV-2 virus has not been fully characterised. Therefore, an analytical study was undertaken using published data to develop a psychrometric model to assess the biological decay rate of the virus in aerosols. This revealed that it is possible to describe with reasonable accuracy (R2 = 0.718, p < 0.001) the biological decay constant for the SARS-CoV-2 virus using a regression model with enthalpy, vapour pressure and specific volume as predictors. Applying this to historical meteorological data from London, Paris and Milan over the pandemic period, produced results which indicate that the average half-life of the virus in aerosols outdoors was in the region 13–22 times longer in March 2020, when the outbreak was accelerating, than it was in August 2020 when epidemic in Europe was at its nadir. However, indoors, this variation is likely to be much less. As such, this suggests that changes in virus survivability due the variations in the psychrometric qualities of the air might influence the transmission of SARS-CoV-2.

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