Long-term studies of Serum Concentrations of reproductively related Steriod Hormones in individual captive Carcharhinids

1992 ◽  
Vol 43 (1) ◽  
pp. 273 ◽  
Author(s):  
LEL Rasmussen ◽  
FL Murru
Keyword(s):  
Steroid Hormones ◽  
Mature Female ◽  
Serum Concentrations ◽  
Carcharhinus Plumbeus ◽  
Short Term ◽  
Serum Samples ◽  
Negaprion Brevirostris ◽  
Serial Serum ◽  
Long Term Studies

Valuable information on maturity and reproductive status can be obtained by the measurement of the concentrations of steroid hormones in the serum of captive carcharhinid sharks. The sharks at Sea World of Florida, Orlando, Florida, include mature females of several species of placental sharks. Serial serum samples from four mature female Carcharhinus plumbeus, one maturing female C. leucas, and one mature and one nearly mature female Negaprion brevirostris were used to determine serum concentrations of 17�-oestradiol, progesterone, testosterone and dihydrotestosterone. The data from these mature placental sharks were then compared with concentrations measured in immature female and male conspecifics and in mature female Eugomphodus taurus (family Odontaspididae). Evidence of repetitive cyclical patterns was obtained from a mature female N. brevirostris. This shark was monitored from June 1988 to July 1990 by means of more than 50 samples that were often obtained at weekly intervals. Concentrations of 17�-oestradiol in the serum of this shark varied in a cyclical fashion, with the highest values obtained in Year 1 (1988-89) being during April (the normal mating season) and those in Year 2 (1989-90) being during June. Concomitant elevations of testosterone concentrations were observed either simultaneously or immediately before or after maximal oestradiol concentrations were noted. Progesterone concentrations were low except for definitive spikes that immediately preceded the maximal concentrations of testosterone and 17�-oestradiol. These periodicities suggest, for placental sharks, that consistently rising oestradiol concentrations may set in motion preovulatory events, that testosterone may be important for the initiation of subsequent ovulatory events, and that transitory elevations of progesterone concentrations may have specific short-term roles. These cyclical changes in the concentrations of steroid hormones observed in captive elasmobranchs support observations of hormone concentrations during reproduction in wild carcharhinids.

Is There a Role for Therapeutic Drug Monitoring of Anti-TNF Monoclonal Antibodies in Inflammatory Bowel Disease

2015 ◽  
Vol 33 (Suppl. 1) ◽  
pp. 70-77 ◽  
Author(s):  
Filip Baert
Keyword(s):  
Monoclonal Antibodies ◽  
Therapeutic Drug Monitoring ◽  
Drug Monitoring ◽  
Treatment Guidelines ◽  
Therapeutic Drug ◽  
Serum Concentrations ◽  
Short Term ◽  
Clear Dose Response ◽  
Inflammatory Bowel

In recent years it has become clear that therapeutic drug monitoring can be an important tool to optimize outcome and costs of anti TNF treatment including the subcutaneous and fully human monoclonal antibodies. There is a clear dose response curve between early serum concentrations of all monoclonal antibodies and response both short term and long term. The wide variations in early serum concentrations are insufficiently explained by classic pharmacokinetic factors. Low early concentrations can lead to anti-drug antibody formation and ensuing loss of response. Therapeutic drug monitoring allows to rationalize the current practice of dose optimization and the use of concomitant immunomodulator treatment. However more prospective studies are needed before strong recommendations can enter treatment guidelines.

Modulatory effect of steroid hormones on GnRH-induced LH secretion by cultured rat pituitary cells

1992 ◽  
Vol 70 (7) ◽  
pp. 963-969 ◽  
Author(s):  
Gabriela T. Pérez ◽  
Marta E. Apfelbaum
Keyword(s):  
Steroid Hormones ◽  
Pituitary Cells ◽  
Short Term ◽  
Stimulatory Action ◽  
Rat Pituitary ◽  
Lh Release ◽  
Gonadotrophin Releasing Hormone ◽  
Rat Pituitary Cells ◽  
Lh Secretion

The purpose of the present experiments was to examine the short- and long-term effects of estradiol-17β (E2), progesterone (P), and 5α-dihydrotestosterone (DHT), alone and in combination, on the gonadotrophin-releasing hormone (GnRH)-induced luteinizing hormone (LH) secretion, using an ovariectomized rat pituitary cells culture model. After 72 h in steroid-free medium, pituitary cells were further cultured for 24 h in medium with or without E2 (1 nM), P (100 nM), or DHT (10 nM). Cultures were then incubated for 5 h in the absence or presence of 1 nM GnRH with or without steroids. LH was measured in the medium and cell extract by radioimmunoassay. The results show that the steroid hormones exert opposite effects on the release of LH induced by GnRH, which seems to be dependent upon the length of time the pituitary cells have been exposed to the steroids. In fact, short-term (5 h) action of E2 resulted in a partial inhibition (64% of control) of LH release in response to GnRH, while long-term (24 h) exposure enhanced (158%) GnRH-induced LH release. Similar results were obtained with DHT, although the magnitude of the effect was lower than with E2. Conversely, P caused an acute stimulatory action (118%) on the LH released in response to GnRH and a slightly inhibitory effect (90%) after chronic treatment. GnRH-stimulated LH biosynthesis was also influenced by steroid treatment. Significant increases in total (cells plus medium) LH were observed in pituitary cells treated with E2 or DHT. While the stimulatory effect of E2 was evident after both acute (133%) and chronic (119%) treatment, that of DHT appears to be exerted mainly after long-term priming (118%). These results suggest that the steroids modulate GnRH-induced LH secretion by acting on both synthesis and release of LH. On the other hand, total hormone content was not affected by P. The acute (5 h) effects of E2, P, and DHT on the GnRH response in E2-primed (24 h) cells during a short-term incubation, were also tested. Addition of P to the pituitary cells primed with E2 led to an acute potentiation of the stimulatory effect of E2 on GnRH-induced LH release and total content. Conversely, the augmentative E2 effect on pituitary responsiveness to GnRH was abolished by DHT. Taken together, these findings suggest that the physiological significance of the stimulatory action of progesterone could be to define the final magnitude of the LH preovulatory surge, while the inhibition by DHT could be required to limit the LH surge to that day of proestrus.Key words: luteinizing hormone, gonadotrophin-releasing hormone, steroid hormones, cultured pituitary cells.

scholarly journals Creatine Use in Sports

2017 ◽  
Vol 10 (1) ◽  
pp. 31-34 ◽  
Author(s):  
Jessica Butts ◽  
Bret Jacobs ◽  
Matthew Silvis
Keyword(s):  
Dietary Supplement ◽  
National Collegiate Athletic Association ◽  
Creatine Supplementation ◽  
Sports Performance ◽  
Short Term ◽  
Level Of Evidence ◽  
Improved Performance ◽  
Google Search ◽  
Long Term Studies

Context: The use of creatine as a dietary supplement has become increasingly popular over the past several decades. Despite the popularity of creatine, questions remain with regard to dosing, effects on sports performance, and safety. Evidence Acquisition: PubMed was searched for articles published between 1980 and January 2017 using the terms creatine, creatine supplementation, sports performance, and dietary supplements. An additional Google search was performed to capture National Collegiate Athletic Association–specific creatine usage data and US dietary supplement and creatine sales. Study Design: Clinical review. Level of Evidence: Level 4. Results: Short-term use of creatine is considered safe and without significant adverse effects, although caution should be advised as the number of long-term studies is limited. Suggested dosing is variable, with many different regimens showing benefits. The safety of creatine supplementation has not been studied in children and adolescents. Currently, the scientific literature best supports creatine supplementation for increased performance in short-duration, maximal-intensity resistance training. Conclusion: While creatine appears to be safe and effective for particular settings, whether creatine supplementation leads to improved performance on the field of play remains unknown.

The influence of mixtures of Stylosanthes spp. accessions on the occurrence of anthracnose caused by Colletotrichum gloeosporioides

1994 ◽  
Vol 45 (1) ◽  
pp. 203 ◽  
Author(s):  
RD Davis ◽  
S Chakraborty ◽  
DF Cameron ◽  
JAG Irwin ◽  
RM Boland
Keyword(s):  
Colletotrichum Gloeosporioides ◽  
Resistant Cultivar ◽  
Pure Stand ◽  
Northern Australia ◽  
Short Term ◽  
Mixed Stands ◽  
The Mean ◽  
Moderately Resistant ◽  
Long Term Studies

The effectiveness of using accession mixtures of Stylosanthes spp. to manage anthracnose (Colletotrichum gloeosporioides) in pastures in northern Australia was examined during three consecutive years. Two mixtures containing six accessions were compared with the components grown as pure stands. No significant differences in anthracnose incidence (proportion of infected plants/plot) were indicated between the two mixtures and the mean incidence of their respective components grown in pure swards. Areas under the disease progress curves for the accessions were not significantly different between pure and mixed stands of the cultivars other than Seca and Verano. Resistant cultivar Seca developed more disease in a mixture than in a pure stand, and moderately resistant Verano had less disease in a mixture than in a pure stand. In the short term, no apparent anthracnose control advantage is achieved in highly susceptible accessions of Stylosanthes spp. when they are included in mixtures with less susceptible accessions. Long term studies involving grazing animals are necessary to adequately evaluate control of this disease through the use of mixtures.

Effectiveness of two tagging devices in the sea cucumber Holothuria (Halodeima) grisea

2017 ◽  
Vol 68 (3) ◽  
pp. 563
Author(s):  
Ruber Rodríguez-Barreras ◽  
Julián López-Morell ◽  
Alberto M. Sabat
Keyword(s):  
Sea Cucumber ◽  
Body Wall ◽  
The Body ◽  
Short Term ◽  
Pit Tag ◽  
Sea Cucumbers ◽  
Pit Tags ◽  
Significant Difference ◽  
Long Term Studies

A reliable and harmless mark–recapture method provides valuable information for the management of commercial sea cucumber species. Nevertheless, marking and tracking sea cucumbers is notoriously difficult and represents a serious challenge. In this study, we tested one external and one internal tag in the sea cucumber Holothuria grisea. A passive integrated transponder (PIT) tag was inserted into the coelomic cavity in one treatment, whereas a T-bar (external tag) was attached in the upper surface of the body wall in the other treatment; sea cucumbers were then followed for 17 weeks. The tagging procedure caused no evisceration in the experimental groups, nor was a significant difference in growth rate found between treatments. The retention of the PIT tag was low, with 100% lost by Week 9. Retention of T-bars was higher, with 90% still attached by the end of the Week 8, but retention decreased thereafter as T-bar absorption increased. No relationship was found between initial weight and the number of weeks PIT tags (r=–0.173, P=0.781) or T-bars (r=–0.220, P=0.652) were retained. Neither the T-bar nor the PIT tags fulfilled the requirements of high retention required for long-term studies. However, we do recommend the use of T-bars for short-term studies for H. grisea under laboratory conditions or in a habitat with low substrate complexity.

scholarly journals Pharmacokinetics of Intravenous Levofloxacin Administered at 750 Milligrams in Obese Adults

2011 ◽  
Vol 55 (7) ◽  
pp. 3240-3243 ◽  
Author(s):  
Aaron M. Cook ◽  
Craig Martin ◽  
Val R. Adams ◽  
R. Scott Morehead
Keyword(s):  
Standard Dose ◽  
Normal Weight ◽  
Serum Concentrations ◽  
Serum Samples ◽  
Obese Adults ◽  
Time Curve ◽  
Physiochemical Properties ◽  
Concentration Time ◽  
Optimal Dosing ◽  
Serial Serum

ABSTRACTThe physiochemical properties of levofloxacin suggest that it is an agent which may exhibit altered pharmacokinetics in obese individuals. The purpose of this study was to describe the pharmacokinetics of a single 750-mg intravenous dose of levofloxacin in both hospitalized and ambulatory obese individuals. The hypothesis was that a standard dose of levofloxacin in obese individuals would achieve serum concentrations likely to be therapeutic. A single levofloxacin dose of 750 mg was infused over 90 min, and seven serial serum samples were subsequently obtained to evaluate the pharmacokinetics after the first dose. The peak concentrations of levofloxacin were comparable to those seen with normal-weight individuals. However, the area under the concentration-time curve and clearance were quite variable. Accelerated clearance was evident in the ambulatory obese individuals. Further investigation of the effects of obesity on the pharmacokinetics of levofloxacin is necessary to ensure optimal dosing.

Nitrogen immobilization in decomposing litter contributes to productivity decline in ageing pastures of green panic (Panicum maximum var. trichoglume)

1989 ◽  
Vol 113 (3) ◽  
pp. 401-406 ◽  
Author(s):  
G. B. Robbins ◽  
J. J. Bushell ◽  
G. M. McKeon
Keyword(s):  
C:N Ratio ◽  
Panicum Maximum ◽  
Short Term ◽  
Term Study ◽  
N Concentration ◽  
Short Term Study ◽  
N Release ◽  
Productivity Decline ◽  
Long Term Studies

SUMMARYThe extent and rate of N release from nylon bags containing green panic (Panicum maximumvar.trichoglume)litter was measured for up to 319 days (long-term studies) in 1978/79 and 1979/80 in Gayndah, Australia. Dry matter (DM) decomposition rates were measured in 41 periods of 39 days and related to environmental variables and initial litter N concentrations (short-term study).About half of litter DM decomposed during the long-term studies, while N concentration in the remaining litter increased from an initial average of 0–57 % N, to 0–95 % N. Net release of N from bags began when its concentration in the residue increased to c.0–65% N (or when the C:N ratio decreased to 75:1). Only a net 20–30 % of the initial N was released for potential plant uptake by the end of the study. The short-term study showed that DM decomposition was rapid and independent of pasture age. Decomposition rate increased with soil moisture and average daily temperature but was unaffected by initial litter N concentration. Release of N from decomposing litter was slow, despite rapid DM decomposition. It was concluded that a major cause of declining productivity in sown grass pastures is the immobilization of N in decomposing grass litter.

scholarly journals Air pollution, SARS-CoV-2 transmission, and COVID-19 outcomes: A state-of-the-science review of a rapidly evolving research area

2020 ◽  
Author(s):  
Anushka Bhaskar ◽  
Jay Chandra ◽  
Danielle Braun ◽  
Jacqueline Cellini ◽  
Francesca Dominici
Keyword(s):  
Air Pollution ◽  
Time Series ◽  
Health Outcomes ◽  
Study Design ◽  
Air Pollutant ◽  
Short Term ◽  
Cross Sectional ◽  
Short And Long Term ◽  
Long Term Studies

Background: As the coronavirus pandemic rages on, 692,000 (August 7, 2020) human lives and counting have been lost worldwide to COVID-19. Understanding the relationship between short- and long-term exposure to air pollution and adverse COVID-19 health outcomes is crucial for developing solutions to this global crisis. Objectives: To conduct a scoping review of epidemiologic research on the link between short- and long-term exposure to air pollution and COVID-19 health outcomes. Method: We searched PubMed, Web of Science, Embase, Cochrane, MedRxiv, and BioRxiv for preliminary epidemiological studies of the association between air pollution and COVID-19 health outcomes. 28 papers were finally selected after applying our inclusion/exclusion criteria; we categorized these studies as long-term studies, short-term time-series studies, or short-term cross-sectional studies. One study included both short-term time-series and a cross-sectional study design. Results: 27 studies of the 28 reported evidence of statistically significant positive associations between air pollutant exposure and adverse COVID-19 health outcomes; 11 of 12 long-term studies and all 16 short-term studies reported statistically significant positive associations. The 28 identified studies included various confounders, spatial and temporal resolutions of pollution concentrations, and COVID-19 health outcomes. Discussion: We discuss methodological challenges and highlight additional research areas based on our findings. Challenges include data quality issues, ecological study design limitations, improved adjustment for confounders, exposure errors related to spatial resolution, geographic variability in testing, mitigation measures and pandemic stage, clustering of health outcomes, and a lack of publicly available data and code.

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