scholarly journals Regulation of pituitary thyrotropin gene expression during Xenopus metamorphosis: negative feedback is functional throughout metamorphosis

2004 ◽  
Vol 182 (2) ◽  
pp. 273-285 ◽  
Author(s):  
RG Manzon ◽  
RJ Denver
Keyword(s):  
Mrna Expression ◽  
Negative Feedback ◽  
Type Ii ◽  
Metamorphic Climax ◽  
Indirect Measures ◽  
Explant Cultures ◽  
Tsh Regulation ◽  
Stimulation Of ◽  
Xenopus Laevis Tadpole

Several hypotheses have been proposed to explain the increase and sustained expression of pituitary thyrotropin (TSH) in the presence of elevated plasma thyroid hormone (TH) concentrations at metamorphic climax in amphibians. It has been proposed that the negative feedback of TH on TSH is inoperative until metamorphic climax, and that it is established at this time by the upregulation of pituitary deiodinase type II (DII); DII converts thyroxine (T(4)) to 3,5,3'-triiodothyronine (T(3)). However, earlier investigators, using indirect measures of TSH, reported that TH negative feedback on TSH was functional in premetamorphic tadpoles. In an effort to understand pituitary TSH regulation during amphibian metamorphosis, we analyzed multiple pituitary genes known or hypothesized to be involved in TSH regulation in tadpoles of Xenopus laevis. Tadpole pituitary explant cultures were used to examine direct negative feedback on TSH mRNA expression. Negative feedback is operative in the early prometamorphic tadpole pituitary and both T(3) and T(4) can downregulate TSH mRNA expression throughout metamorphosis. The expression of both DII and TH receptor betaA mRNAs increased during development and peaked at climax; however, these increases coincided with similar increases in deiodinase type III, which inactivates TH. Moreover, corticotropin-releasing factor (CRF) receptors, CRF binding protein and thyrotropin-releasing hormone receptor type 2 mRNA expression also peaked at climax. Our data suggest that the regulation of TSH is more complex than the timing of DII expression, and likely involves a balance between stimulation of TSH synthesis and secretion by neuropeptides (e.g. CRF) of hypothalamic or pituitary origin, increased pituitary sensitivity to neuropeptides through upregulation of their receptors, and intrapituitary TH levels.

scholarly journals A New Model for Adrenarche: Inhibition of 3β-Hydroxysteroid Dehydrogenase Type 2 by Intra-Adrenal Cortisol

2018 ◽  
Vol 89 (5) ◽  
pp. 311-319
Author(s):  
Joseph A. Majzoub ◽  
Lisa Swartz Topor
Keyword(s):  
Negative Feedback ◽  
Serum Cortisol ◽  
Hydroxysteroid Dehydrogenase ◽  
Cortisol Concentration ◽  
Childhood Growth ◽  
Adrenal Steroidogenesis ◽  
Steroidogenic Cells ◽  
Serum Cortisol Concentration ◽  
Stimulation Of

We propose that the normal adrenarche-related rise in dehydroepiandrosterone (DHEA) secretion is ultimately caused by the rise in cortisol production occurring during childhood and adolescent growth, by the following mechanisms. (1) The onset of childhood growth leads to a slight fall in serum cortisol concentration due to growth-induced dilution and a decrease in the negative feedback of cortisol upon ACTH secretion. (2) In response, ACTH rises and stimulates increased cortisol synthesis and secretion in the growing body to restore the serum cortisol concentration to normal. (3) The cortisol concentration produced within and taken up by adrenocortical steroidogenic cells may rise during this time. (4) Cortisol competitively inhibits 3β-hydroxysteroid dehydrogenase type 2 (3βHSD2)-mediated conversion of 17αOH-pregnenolone to cortisol, causing a further fall in serum cortisol, a further decrease in the negative feedback of cortisol upon ACTH, a further rise in ACTH, and further stimulation of adrenal steroidogenesis. (5) The cortisol-mediated inhibition of 3βHSD2 also blocks the conversion of DHEA to androstenedione, causing a rise in adrenal DHEA and DHEA sulfate relative to androstenedione secretion. Thus, the combination of normal body growth plus inhibition of 3βHSD2 by intra-adrenal cortisol may cause normal adrenarche. Childhood obesity may hasten this process by causing a pathologic increase in body size that triggers these same processes at an earlier age, resulting in the premature onset of adrenarche.

Peripheral mononuclear TNF-α, visfatin, and resistin mRNA expression in overweight women with type 2 diabetes

2007 ◽  
Vol 2 (04) ◽  
Author(s):  
P Tsiotra ◽  
C Tsigos ◽  
E Yfanti ◽  
E Anastasiou ◽  
SA Raptis
Keyword(s):  
Type 2 Diabetes ◽  
Mrna Expression ◽  
Overweight Women ◽  
Tnf Α ◽  
Resistin Mrna

A determination of excitability changes in dorsal spinocerebellar tract neurons from spike-train analysis

1977 ◽  
Vol 40 (3) ◽  
pp. 626-646 ◽  
Author(s):  
C. K. Knox ◽  
S. Kubota ◽  
R. E. Poppele
Keyword(s):  
Spike Train ◽  
Afferent Input ◽  
Complex Interactions ◽  
Group I ◽  
Long Latency ◽  
Cross Correlation Analysis ◽  
Output Spike ◽  
Type 3 ◽  
Stimulation Of

1. Responses of DSCT neurons to random electrical stimulation of peripheral nerves of the hindleg at group I intensity were studied using cross-correlation analysis of the output spike train with the stimulus. Three types of response were found: type 1 was due to monosynaptic activation of DSCT cells, type 2 resulted from inhibition of those cells, and type 3 was due to a long-latency excitation that was probably polysynaptic. 2. Most of the units studied responded to stimulation of both proximal and distal flexor and extensor nerves. The extensive convergence of afferent input on DSCT cells is much greater than has been observed previously, with type 2 and type 3 responses totaling 80% of the observed responses. We attribute this to the sensitivity of the analysis in detecting small changes in postsynaptic excitability. 3. The results of the study, particularly the derivation of postsynaptic excitability changes, generally confirm those of earlier work employing intracellular recording. 4. By varying stimulus rate and stimulus intensity in the group 1 range and simulating the resulting correlations, we conclude that excitability changes in DSCT cells are the net result of complex interactions involving excitation and inhibition. A summary of these findings is presented as a model for the minimum circuitry necessary to account for the observed behavior.

scholarly journals Effectiveness of two procedures for deploying a facilitated collaborative modeling implementation strategy—the PVS-PREDIAPS strategy—to optimize type 2 diabetes prevention in primary care: the PREDIAPS cluster randomized hybrid type II implementation trial

2021 ◽  
Vol 16 (1) ◽  
Author(s):  
Alvaro Sanchez ◽  
◽  
Susana Pablo ◽  
Arturo Garcia-Alvarez ◽  
Silvia Dominguez ◽  
...  
Keyword(s):  
Type 2 Diabetes ◽  
Primary Care ◽  
Diabetes Prevention ◽  
Implementation Strategy ◽  
Type Ii ◽  
Collaborative Process ◽  
Type 2 Diabetes Prevention ◽  
Cluster Randomized ◽  
Implementation Trial

Abstract Background The most efficient procedures to engage and guide healthcare professionals in collaborative processes that seek to optimize practice are unknown. The PREDIAPS project aims to assess the effectiveness and feasibility of different procedures to perform a facilitated interprofessional collaborative process to optimize type 2 diabetes prevention in routine primary care. Methods A type II hybrid cluster randomized implementation trial was conducted in nine primary care centers of the Basque Health Service. All centers received training on effective healthy lifestyle promotion. Headed by a local leader and an external facilitator, centers conducted a collaborative structured process—the PVS-PREDIAPS implementation strategy—to adapt the intervention and its implementation to their specific context. The centers were randomly allocated to one of two groups: one group applied the implementation strategy globally, promoting the cooperation of all health professionals from the beginning, and the other performed it sequentially, centered first on nurses, who later sought the pragmatic cooperation of physicians. The following patients were eligible for inclusion: all those aged ≥ 30 years old with at least one known cardiovascular risk factor and an impaired fasting glucose level (≥ 110-125 mg/dl) but without diabetes who attended centers during the study period. The main outcome measures concerned changes in type 2 diabetes prevention practice indicators after 12 months. Results After 12 months, 3273 eligible patients at risk of type 2 diabetes had attended their family physician at least once, and of these, 490 (15%) have been addressed by assessing their healthy lifestyles in both comparison groups. The proportion of at-risk patients receiving a personalized prescription of lifestyle change was slightly higher (8.6%; range 13.5-5.9% vs 6.8%; range 7.2-5.8%) and 2.3 times more likely (95% CI for adjusted hazard ratio, 1.38-3.94) in the sequential than in the global centers, after 8 months of the intervention program implementation period. The probability of meeting the recommended levels of physical activity and fruit and vegetable intake were four- and threefold higher after the prescription of lifestyle change than only assessment and provision of advice. The procedure of engagement in and execution of the implementation strategy does not modify the effect of prescribing healthy habits (p interaction component of intervention by group, p > 0.05). Discussion Our results show that the PVS-PREDIAPS implementation strategy manages to integrate interventions with proven efficacy in the prevention of type 2 diabetes in clinical practice in primary care. Further, they suggest that implementation outcomes were somewhat better with a sequential facilitated collaborative process focused on enhancing the autonomy and responsibility of nurses who subsequently seek a pragmatic cooperation of GPs. Trial registration Clinicaltrials.gov identifier: NCT03254979. Registered 16 August 2017—retrospectively registered.

scholarly journals Dengue Virus Induces the Expression and Release of Endocan from Endothelial Cells by an NS1–TLR4-Dependent Mechanism

2021 ◽  
Vol 9 (6) ◽  
pp. 1305
Author(s):  
Carlos Alonso Domínguez-Alemán ◽  
Luis Alberto Sánchez-Vargas ◽  
Karina Guadalupe Hernández-Flores ◽  
Andrea Isabel Torres-Zugaide ◽  
Arturo Reyes-Sandoval ◽  
...  
Keyword(s):  
Endothelial Cell ◽  
Mrna Expression ◽  
Cell Lines ◽  
Cell Activation ◽  
Dengue Infection ◽  
Elevated Serum ◽  
Fold Increase ◽  
Endothelial Cell Activation ◽  
Stimulation Of

A common hallmark of dengue infections is the dysfunction of the vascular endothelium induced by different biological mechanisms. In this paper, we studied the role of recombinant NS1 proteins representing the four dengue serotypes, and their role in promoting the expression and release of endocan, which is a highly specific biomarker of endothelial cell activation. We evaluated mRNA expression and the levels of endocan protein in vitro following the stimulation of HUVEC and HMEC-1 cell lines with recombinant NS1 proteins. NS1 proteins increase endocan mRNA expression 48 h post-activation in both endothelial cell lines. Endocan mRNA expression levels were higher in HUVEC and HMEC-1 cells stimulated with NS1 proteins than in non-stimulated cells (p < 0.05). A two-fold to three-fold increase in endocan protein release was observed after the stimulation of HUVECs or HMEC-1 cells with NS1 proteins compared with that in non-stimulated cells (p < 0.05). The blockade of Toll-like receptor 4 (TLR-4) signaling on HMEC-1 cells with an antagonistic antibody prevented NS1-dependent endocan production. Dengue-infected patients showed elevated serum endocan levels (≥30 ng/mL) during early dengue infection. High endocan serum levels were associated with laboratory abnormalities, such as lymphopenia and thrombocytopenia, and are associated with the presence of NS1 in the serum.

scholarly journals A youngest reported case of type II Monteggia lesion associated with a posterior ulnohumeral dislocation

2019 ◽  
Vol 26 (1) ◽  
pp. 23-25
Author(s):  
Avadhoot Kantak
Keyword(s):  
Upper Limb ◽  
Injury Pattern ◽  
Type Ii ◽  
Rare Injury ◽  
Monteggia Lesion ◽  
Injury Mechanisms ◽  
High Incidence ◽  
Limb Fractures ◽  
Upper Limb Fractures

Monteggia fractures are uncommon injuries, despite a high incidence of upper limb fractures in teenage children. We describe a case of a type 2 Monteggia variant in an adolescent. This injury pattern consisted of ulnohumeral dislocation in combination with type 2 Monteggia lesion. We discuss the possible injury mechanisms of this rare injury and review available literature.

Sign in / Sign up

Export Citation Format

Share Document