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1.
Rev Sci Instrum ; 94(8)2023 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-38065142

RESUMO

During deposition, modification, and etching of thin films and nanomaterials in reactive plasmas, many active species can interact with the sample simultaneously. This includes reactive neutrals formed by fragmentation of the feed gas, positive ions, and electrons generated by electron-impact ionization of the feed gas and fragments, excited states (in particular, long-lived metastable species), and photons produced by spontaneous de-excitation of excited atoms and molecules. Notably, some of these species can be transiently present during the different phases of plasma processing, such as etching of thin layer deposition. To monitor plasma-surface interactions during materials processing, a new system combining beams of neutral atoms, positive ions, UV photons, and a magnetron plasma source has been developed. This system is equipped with a unique ensemble of in-plasma surface characterization tools, including (1) a Rutherford Backscattering Spectrometer (RBS), (2) an Elastic Recoil Detector (ERD), and (3) a Raman spectroscopy system. RBS and ERD analyses are carried out using a differentially pumped 1.7 MV ion beam line Tandetron accelerator generating a beam at grazing incidence. The ERD system is equipped with an absorber and is specifically used to detect H initially bonded to the surface; higher resolution of surface H is also available through nuclear reaction analysis. In parallel, an optical port facing the substrate is used to perform Raman spectroscopy analysis of the samples during plasma processing. This system enables fast monitoring of a few Raman peaks over nine points scattered on a 1.6 × 1.6 mm2 surface without interference from the inherent light emitted by the plasma. Coupled to the various plasma and beam sources, the unique set of in-plasma surface characterization tools detailed in this study can provide unique time-resolved information on the modification induced by plasma. By using the ion beam analysis capability, the atomic concentrations of various elements in the near-surface (e.g., stoichiometry and impurity content) can be monitored in real-time during plasma deposition or etching. On the other hand, the evolution of Raman peaks as a function of plasma processing time can contribute to a better understanding of the role of low-energy ions in defect generation in irradiation-sensitive materials, such as monolayer graphene.

3.
Lupus ; 28(2): 156-162, 2019 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-30509154

RESUMO

OBJECTIVE: Patients with systemic lupus erythematosus (SLE) have altered bone metabolism and are at risk of osteoporosis. The aim of this study was to examine bone turnover markers in relation to vitamin D, disease activity, and clinical risk factors in patients with established SLE. METHODS: Clinical registry and biorepository data of 42 SLE patients were assessed. Serum samples were analyzed for osteocalcin as a marker of bone formation, C-terminal telopeptide of type 1 collagen (CTX) as a marker for bone resorption, and 25-hydroxy vitamin D. RESULTS: Patients with a Systemic Lupus Erythematosus Disease Activity Index 2000 (SLEDAI) score of 3 or greater had a lower median osteocalcin level ( P = 0.02) and lower 25-hydroxy vitamin D levels ( P = 0.03) than those with a score of less than 3. No significant differences in bone turnover markers were observed between patients dichotomized into subgroups using a 25-hydroxy vitamin D cut-off of 30 ng/mL or by a daily prednisone dose greater than or 5 mg or less. Osteocalcin levels were negatively correlated with SLEDAI scores ( P = 0.034), and were positively correlated with the CTX index (a ratio of measured CTX value to the upper limit of the normal value for age and gender) ( P < 0.01). No association between the CTX index and SLEDAI scores was found. CONCLUSION: SLE disease activity may have direct effects on bone formation, but no effects on bone resorption in this cohort of established SLE patients, probably related to the inflammation-suppressing effects of glucocorticoids, thereby inhibiting cytokine-induced osteoclast activity. A fine balance exists between disease control and the use of glucocorticoids with regard to bone health.


Assuntos
Remodelação Óssea , Lúpus Eritematoso Sistêmico/sangue , Lúpus Eritematoso Sistêmico/fisiopatologia , Osteoporose/sangue , Vitamina D/análogos & derivados , Adulto , Biomarcadores/sangue , Colágeno Tipo I/sangue , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Osteocalcina/sangue , Peptídeos/sangue , Índice de Gravidade de Doença , Vitamina D/sangue
4.
Transplant Proc ; 50(2): 374-381, 2018 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-29579807

RESUMO

BACKGROUND: In 2011, the European Directorate for the Quality of Medicines & Healthcare of the Council of Europe launched a 3-year collaborative project to address the organ shortage and improve access to transplant health services in Council of Europe member states in the Black Sea area (Armenia, Azerbaijan, Bulgaria, Georgia, Moldova, Romania, Turkey, Ukraine, and the Russian Federation) through the development of safe and ethical donation and transplantation programs. OBJECTIVE: Support the development of donation and transplantation programs through close interstate cooperation between national health organizations and relevant stakeholders. METHODOLOGY: Several work packages (WP) were established: WP1, project coordination (European Directorate for the Quality of Medicines & Healthcare); WP2, development and implementation of an effective legislative and financial framework (Czech Republic and France); WP3, establishment of National Transplant Authorities (Italy and Portugal); and WP4, clinical practices (DTI Foundation). Data collection, surveys, and expert visits allowed for the collection of first-hand information from each participant country at national, regional, and hospital levels. RESULTS: Data analysis showed the positive impact of the project represented by a tendency to increase the total donation rates (per million people) in the participant countries (2011 vs 2013): Azerbaijan, +7.3; Armenia, -0.7; Georgia, +3.3; Bulgaria, +0.9; Moldova, +2.5; Ukraine:, +0.8; Romania, +2.3; and Turkey, +2.7. CONCLUSIONS: Increases in total donation rates are the result of a number of initiatives in the Black Sea area, including the stepwise implementation of legislative, organizational and institutional country-specific recommendations tailored by the CoE, efforts of the respective Ministries of Health in each country and synergism with other European projects in the region. These countries should invest further in implementing the recommendations that emerged from this project to improve their organ donation and transplantation programs and progress toward self-sufficiency.


Assuntos
Cooperação Internacional , Obtenção de Tecidos e Órgãos/organização & administração , Transplantes/provisão & distribuição , Mar Negro , França , Humanos , Itália , Moldávia , Portugal , Romênia , Turquia
5.
Sci Rep ; 7(1): 2503, 2017 05 31.
Artigo em Inglês | MEDLINE | ID: mdl-28566679

RESUMO

We report the successful demonstration of a hybrid system that combines pulsed laser deposition (PLD) and magnetron sputtering (MS) to deposit high quality thin films. The PLD and MS simultaneously use the same target, leading to an enhanced deposition rate. The performance of this technique is demonstrated through the deposition of titanium dioxide and bismuth-based perovskite oxide Bi2FeCrO6 (BFCO) thin films on Si(100) and LaAlO3 (LAO) (100). These specific oxides were chosen due to their functionalities, such as multiferroic and photovoltaic properties (BFCO) and photocatalysis (TiO2). We compare films deposited by conventional PLD, MS and PLD combined with MS, and show that under all conditions the latter technique offers an increased deposition rate (+50%) and produces films denser (+20%) than those produced by MS or PLD alone, and without the large clusters found in the PLD-deposited films. Under optimized conditions, the hybrid technique produces films that are two times smoother than either technique alone.

6.
J Acoust Soc Am ; 132(5): 3076-85, 2012 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-23145593

RESUMO

Laboratory grade bistatic scattering measurements are conducted in order to examine the acoustic response of realistic fully buried unexploded ordnance (UXO) from above-critical angle insonification, between 2 and 40 kHz. A 127 mm diameter rocket UXO, a 155 mm diameter artillery shell, a natural rock of approximately the same size, and a cinder block are fully buried in water-saturated medium grained sand (mean grain diameter, 240 µm) at depths of 10 cm below the water-sediment interface. A two-dimensional array of bistatic scattering measurements is generated synthetically by scanning a single hydrophone in steps of 3 cm over a 1 m × 1 m patch directly above the targets at a height of 20 cm above the water-sediment interface. Three-dimensional volumetric acoustic images generated from the return waveforms reveal scattering components attributed to geometric and elastic scattering, as well as multiple-scattering interactions of returns between the sediment-water interface and the buried objects. The far-field target strength of the objects is estimated through extrapolation of the angular spectrum. Agreement is found between experimental data and simulated data generated from a finite-element-based, three-dimensional time-harmonic model (2-25 kHz). Separation of the measured UXO from the clutter objects is demonstrated through exploitation of structural-acoustics-based features.


Assuntos
Acústica , Armas de Fogo , Processamento de Sinais Assistido por Computador , Som , Acústica/instrumentação , Simulação por Computador , Análise de Elementos Finitos , Análise de Fourier , Sedimentos Geológicos , Modelos Teóricos , Movimento (Física) , Análise Numérica Assistida por Computador , Espalhamento de Radiação , Dióxido de Silício , Espectrografia do Som , Fatores de Tempo , Transdutores , Água
7.
J Acoust Soc Am ; 129(6): 3453-6, 2011 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-21682369

RESUMO

A 48 m rail with a moving receiver was used to measure forward scattering from a spherical shell lying on the bottom in the Gulf of Mexico. The target was mid-way between the source and rail, on a line from the source bisecting the rail. The major obstacle to the measurement of forward scattering is the much stronger source signal which overlaps the scattered signal in space and time. Here, forward scattered target strength is obtained by processing the received signals using a wavenumber filter to remove the incident wave. The result compares favorably to that obtained from numerical predictions.


Assuntos
Acústica , Processamento de Sinais Assistido por Computador , Som , Acústica/instrumentação , Simulação por Computador , Desenho de Equipamento , Análise de Fourier , Sedimentos Geológicos , Movimento (Física) , Análise Numérica Assistida por Computador , Oceanos e Mares , Espectrografia do Som , Fatores de Tempo , Transdutores
8.
J Acoust Soc Am ; 129(5): 2979-90, 2011 May.
Artigo em Inglês | MEDLINE | ID: mdl-21568401

RESUMO

This paper describes a high-order, finite-element-based, three-dimensional time-harmonic model for large-scale exterior structural-acoustics problems. It is applicable to both freefield and littoral environments. For the freefield case, the infinite exterior is treated as a homogeneous linear acoustic medium. For littoral applications, the water or air and the sediment domains are each treated as linear homogeneous, semi-infinite half-spaces with piecewise-constant properties. Both domains admit complex-valued wave speeds to enable the inclusion of damping. The finite element formulation uses a variational statement which naturally incorporates the transmission-condition at the water or air-sediment interface. The truncation of the infinite exterior is realized using an infinite-element for the freefield case, and the perfectly-matched-layer approximation for littoral applications. Computation of the farfield quantities is done based on an integral representation which, for the littoral cases, uses efficient approximations for the appropriate Green's function. Numerical computations are presented for a series of progressively more complex problems, and are used to verify the model against analytic and other numerical solutions and validate it based on the experimental data for scattering from elastic scatterers as measured in freefield and sediment pool laboratory facilities.

9.
Appl Radiat Isot ; 64(5): 556-62, 2006 May.
Artigo em Inglês | MEDLINE | ID: mdl-16406548

RESUMO

The development of clinical treatments involving the use of beta-emitting millimetric and sub-millimetric devices has been a continuing trend in nuclear medicine. Implanted a few nanometers below the surface of endovascular implants, seeds or beads, beta-emitting radioisotopes can be used in a variety of biomedical applications. Recently, new technologies have emerged to enable the rapid and efficient activation of such devices. A pulsed, coaxial electron cyclotron resonance plasma reactor was designed and tested to demonstrate the feasibility of plasma-based radioactive ion implantation (PBRII). It has been shown that such plasma reactors allow for the implantation of radioisotopes (32P) into biomedical devices with higher efficiencies than those obtained with conventional ion beams. Fragments containing radioactive atoms are produced in the implanter by means of a negatively biased solid sputter cathode that is inserted into an argon plasma. Dilute orthophosphoric acid solutions (H3(32)PO4) are used for the fabrication of flat sputter targets, since they offer a high radioisotope content. However, the aggregation of the radioactive solute into highly hygroscopic ring-like deposits rather than flat, thin radioactive films is observed on certain substrates. This article describes the effect of this nonuniform distribution of the radioisotopes on the efficiency of PBRII, and presents a technique which enables a better distribution of 32P by coating the substrates with iron. The iron coating is shown to enable optimal radioisotope sputtering rates, which are essential in 32P-PBRII for the efficient activation of millimetric biomedical devices such as stents or coils.


Assuntos
Ácidos Fosfóricos/química , Radioisótopos de Fósforo/química , Próteses e Implantes , Ouro/química , Humanos , Ferro/química , Radioisótopos de Fósforo/uso terapêutico , Silício/química
10.
Endocrinology ; 146(10): 4472-8, 2005 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-15976054

RESUMO

The discovery of tetrahydrogestrinone (THG) abuse by several elite athletes led the U.S. Congress to declare it a controlled substance, although conclusive evidence of its anabolic/androgenic activity is lacking. We determined whether THG affects myogenic differentiation and androgen receptor (AR)-mediated signaling, whether it binds to AR, and whether it has androgenic and anabolic effects in vivo. Accordingly, we measured the dissociation constant for THG with a fluorescence anisotropy assay using recombinant AR-ligand binding domain. The AR nuclear translocation and myogenic activity of androstenedione were evaluated in mesenchymal, multipotent C3H10T1/2 cells. We performed molecular modeling of the THG:AR interaction. The androgenic/anabolic activity was evaluated in orchidectomized rats. THG bound to AR with an affinity similar to that of dihydrotestosterone. In multipotent C3H10T1/2 cells, THG upregulated AR expression, induced AR nuclear translocation, dose dependently increased the area of myosin heavy chain type II-positive myotubes, and up-regulated myogenic determination and myosin heavy chain type II protein expression. The interaction between AR and the A ring of THG was similar to that between AR and the A ring of dihydrotestosterone, but the C17 and C18 substituents in THG had a unique stabilizing interaction with AR. THG administration prevented the castration-induced atrophy of levator ani, prostate gland, and seminal vesicles and loss of fat-free mass in orchidectomized rats. We conclude that THG is an anabolic steroid that binds to AR, activates AR-mediated signaling, promotes myogenesis in mesenchymal multipotent cells, and has anabolic and androgenic activity in vivo. This mechanism-based approach should be useful for rapid screening of anabolic/androgenic agents.


Assuntos
Gestrinone/análogos & derivados , Mesoderma/fisiologia , Músculo Esquelético/citologia , Receptores Androgênicos/fisiologia , Animais , Diferenciação Celular/efeitos dos fármacos , Células Cultivadas , Gestrinone/farmacologia , Masculino , Mesoderma/citologia , Mesoderma/efeitos dos fármacos , Camundongos , Músculo Esquelético/efeitos dos fármacos , Orquiectomia , Ratos
11.
Pediatr Nephrol ; 16(9): 728-32, 2001 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-11511987

RESUMO

To study prospectively the risk factors and etiology of urolithiasis in all stone patients aged <15 years admitted from 1991 to 1999 to the Arabkir hospital in Yerevan. Stones were obtained by surgery (64%), extracorporeal shockwave lithotripsy (ESWL) (7%) or cystoscopic extraction (4%); 25% passed spontaneously. All were examined by infrared spectroscopy, and spot urines were analyzed chemically. 198 patients, 180 (68% males) with renal stones and 18 (83% males) with primary bladder stones, were studied. Calcium oxalate (CaOx) was the predominant constituent in 62% of the kidney stones, followed by struvite (17%), calcium phosphate (7%), uric acid (7%), ammonium acid urate (5%), and cystine (2%). Bladder stones contained CaOx in 72%, uric acid in 22% and ammonium acid urate in 6% of patients. Etiology was obviously metabolic in 5% and possibly metabolic in 26%. Twenty percent of stones were infectious, and 19% were endemic (9% bladder and 10% kidney stones); 4% were secondary to urinary stasis with malformation but no infection. Etiology in 26% remained unknown. Stone composition and metabolic etiology are similar to that in central Europe and North America. In contrast, infectious calculi and particularly endemic stones are still common, although becoming less so now. Urolithiasis in Armenia thus reflects the transition from a rural to an urban society.


Assuntos
Cálculos Urinários/etiologia , Adolescente , Armênia/epidemiologia , Criança , Pré-Escolar , Humanos , Estudos Prospectivos , Fatores de Risco , Fatores de Tempo , Cálculos Urinários/química , Cálculos Urinários/epidemiologia
12.
Eur J Pediatr ; 160(3): 173-6, 2001 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-11277379

RESUMO

We report on two children, a 12-year-old boy and a 6-year-old girl, with simultaneous occurrence of clinical and laboratory features consistent with both diarrhoea-negative haemolytic uraemic syndrome (D-HUS) and acute post-infectious glomerulonephritis (APGN). Both presented with acute renal insufficiency, hypertension and oedema. Laboratory evaluation revealed micro-angiopathic anaemia with burr cells, thrombocytopenia, elevated lactic dehydrogenase and low complement C3. Urinalysis showed marked proteinuria and haematuria. Renal biopsy was characteristic of APGN, but not of HUS. The outcome was good in both children. Conclusion. The simultaneous occurrence of diarrhoea-negative haemolytic uraemic syndrome and acute post-infectious glomerulonephritis is rare. The outcome is generally good as is expected in the latter condition in contrast to the former.


Assuntos
Glomerulonefrite/complicações , Síndrome Hemolítico-Urêmica/complicações , Doença Aguda , Criança , Feminino , Glomerulonefrite/patologia , Síndrome Hemolítico-Urêmica/patologia , Humanos , Masculino , Prognóstico
14.
Arch Dis Child ; 77(4): 342-4, 1997 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-9389241

RESUMO

AIM: To evaluate the presentation and course of acute postinfectious glomerulonephritis (APGN), which has increased dramatically in Armenia after serious deterioration in the living conditions. STUDY DESIGN: Observational study, based on case notes, of a large homogeneous group of patients hospitalised for APGN at one centre over a five year period (1992-6). PATIENTS: 474 patients aged < 16 years with a diagnosis of APGN. RESULTS: The annual number of patients increased tenfold from 19 (average 1992/3) to 196 in 1995. Sixty two per cent were in the age group 4-9 years and 65% were boys. Upper respiratory infections, scarlet fever, and skin infections preceded APGN in 51%, 23%, and 13%, respectively. All patients had haematuria (93% gross), 84% had oedema, and 72% had hypertension. C3 was initially decreased in 95% of the patients examined. Renal function was impaired (serum creatinine > 100 mumol/l) in 29%. Four patients with renal failure had crescentic glomerulonephritis at biopsy; of these, three required temporary haemodialysis. Main extrarenal complications were heart failure (10%) and convulsions (3%). One patient died and five (3%) did not recover completely. CONCLUSIONS: APGN in children is associated with considerable initial morbidity, and long term outcome is not uniformly benign. Outbreaks of APGN may occur anytime in countries such as Armenia that are suffering from a sudden decline in socioeconomic conditions.


Assuntos
Surtos de Doenças , Glomerulonefrite/epidemiologia , Infecções/epidemiologia , Doença Aguda , Adolescente , Distribuição por Idade , Armênia/epidemiologia , Criança , Pré-Escolar , Feminino , Glomerulonefrite/microbiologia , Humanos , Lactente , Masculino , Infecções Respiratórias/epidemiologia , Escarlatina/epidemiologia , Distribuição por Sexo , Dermatopatias Infecciosas/epidemiologia , Fatores Socioeconômicos
15.
J Endocrinol Invest ; 20(7): 381-6, 1997.
Artigo em Inglês | MEDLINE | ID: mdl-9309535

RESUMO

The in vitro immunoreactive (i-LH) and bioactive (b-LH) LH release from hemipituitaries of intact adult male rats (INT) or rats castrated 7 days earlier (CAS) was studied. Hemipituitaries were incubated for 30 min (time 1) plus an additional 30 min (time 2) with GnRH (10 nM) and/or KCl (50 mM), according to one of the following protocols: media alone (C), KCl+KCl (K/K), GnRH+GnRH (G/G), KCl+GnRH (K/G), GnRH+KCl (G/K). All of the hemipituitaries were further incubated in media alone for 120 min (time 3). I-LH, b-LH and i-FSH were assayed on the media. In both models, the highest bioactive:immunoactive (b/i) ratio was noted during time 1; however, CAS always secreted more b-LH than INT at any given time of the study. In INT, GnRH--but not KCl--administration during time 2 resulted in blunted i-LH. During the same time, the b/i ratios decreased in all groups but G/K. LH secretion recovered during time 3 in all groups. In CAS, i-LH levels comparable to those of time 1 were sustained by either stimulus during time 2, while the b/i ratios were markedly decreased. LH secretion recovered in the K/K group during time 3. These results suggest that: 1) promptly releasable pools of b-LH are available in both models; 2) CAS always secrete more b-LH; 3) in INT, desensitization occurs involving parallel changes in both i-LH and b-LH, while changes in b-LH rather than i-LH are noted in CAS; 4) prolonged KCl administration might play a role in new gonadotropin synthesis and/or release.


Assuntos
Hormônio Liberador de Gonadotropina/farmacologia , Hormônio Luteinizante/metabolismo , Orquiectomia , Hipófise/metabolismo , Cloreto de Potássio/farmacologia , Animais , Técnicas In Vitro , Masculino , Hipófise/efeitos dos fármacos , Ratos , Ratos Sprague-Dawley
16.
J Neuroendocrinol ; 7(9): 673-9, 1995 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-8547944

RESUMO

A technique for sorting live LH- and FSH-secreting cells was developed. After enzymatic dispersion, a suspension of pituitary cells from male rats castrated 7 days earlier was incubated in potassium chloride (KCI 50 mmol/l) for 30 min and gonadotropin outflow was provoked. Then, considering either LH or FSH as temporary surface markers, we positively selected the secreting cells by means of antibodies toward either LH (anti-LH beads) or FSH (anti-FSH beads) covalently attached to magnetic beads. The spontaneous secretion of LH and FSH overnight and the release induced by KCI the following morning were calculated. A population enriched in gonadotropes (16% of the total) able to secrete both gonadotropins was selected by means of anti-LH beads; this released 7 times as much LH as non-selected cells. A similar population (14% of the total) was selected by means of anti-FSH-coated beads; this produced 3.3 times as much LH as non-selected cells. In some experiments, the cells not previously sorted with anti-LH-coated beads were further incubated in the presence of anti-FSH beads, in an attempt to isolate a population secreting only FSH. A limited number of cells were sorted (6% of the total cells), able to produce both gonadotropins, but with a lower LH/FSH ratio. Similarly, those cells excluded by the selection with anti-FSH beads were further incubated with anti-LH beads, with a view to obtaining only-LH-secreting cells. However, both gonadotropins were still secreted by these cells (8% of the total), which had the highest LH/FSH ratio. In conclusion, fractions from castrated male rats that are enriched in gonadotropes contain cells that secrete both gonadotropins in vitro. The secretion of LH is prevalent. However, differences in the LH/FSH ratio between the populations sorted and changes from spontaneous to stimulated release are observed. This suggests that some gonadotropes might 'specialize' in releasing LH and others in releasing both LH and FSH.


Assuntos
Anticorpos/imunologia , Hormônio Foliculoestimulante/imunologia , Hormônio Luteinizante/imunologia , Magnetismo , Hipófise/metabolismo , Animais , Masculino , Hipófise/imunologia , Radioimunoensaio , Ratos , Ratos Sprague-Dawley
17.
J Androl ; 14(2): 124-9, 1993.
Artigo em Inglês | MEDLINE | ID: mdl-8514618

RESUMO

Cultured Leydig tumor cells (MA-10) respond to luteinizing hormone (LH) by synthesizing and secreting progesterone (P). The specificity of the response to LH prompted us to develop this system for use as a simple and rapid in vitro bioassay for LH. The aims of this study were to (1) improve sensitivity and reproducibility, and (2) optimize the assay for use in diverse animal species. A minimum sensitivity was observed at 0.05 mlU/well of LH with 0.5 x 10(4) cells/well for 1.5 hours. At higher concentrations of LH, shorter incubation periods also significantly stimulated P production. Addition of human LH standard or serum samples resulted in a dose-dependent increase in P production. Parallel dose-dependent curves were observed with LH preparations from mammalian, avian, and amphibian species. In conclusion, these findings demonstrate that (1) the assay is rapid, sensitive, and reproducible; (2) serum LH levels analyzed using this assay and the mouse Leydig cell bioassay are comparable; (3) shorter incubation times suggest the implementation of this assay for rapid qualitative determination of LH surges; and (4) the assay can be used for the analysis of samples from diverse species, especially those lacking radioimmunoassays. Therefore, this assay system allows for the simple and rapid measurement of circulating bioactive LH levels in humans and diverse animal species, and should provide insight regarding the role of bioactive LH in physiological and pathological conditions.


Assuntos
Bioensaio/métodos , Hormônio Luteinizante/análise , Adulto , Animais , Meios de Cultura , Estudos de Avaliação como Assunto , Feminino , Humanos , Células Intersticiais do Testículo , Hormônio Luteinizante/fisiologia , Masculino , Camundongos , Hipófise/metabolismo , Progesterona/biossíntese , Reprodutibilidade dos Testes , Sensibilidade e Especificidade , Especificidade da Espécie , Células Tumorais Cultivadas
18.
Biol Reprod ; 48(2): 333-9, 1993 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-8439622

RESUMO

Reproductive aging in female rats is associated with a transition from regular estrous cyclicity to an anovulatory condition described as persistent estrous (PE). This PE condition is characterized by continued follicular development with elevated circulating levels of estrogen and FSH. In an attempt to investigate further the age-related changes in neuroendocrine function of PE rats, we have developed a model through which the return of hypothalamic-pituitary and ovarian function can be assessed following the withdrawal of chronic LHRH agonist suppression. Subsequent to withdrawal of continuous (2.5 micrograms/h for 12 days) LHRH agonist [DTrp6, Pro9-NHEt]-LHRH (LHRH-AG) treatment, circulating FSH concentrations in PE rats increase and remain elevated with an apparent absence of ovarian negative feedback, and these rats fail to return to estrous cyclicity. In the present studies, estrogen administration induced significant decreases in FSH secretion in PE rats following withdrawal of LHRH-AG treatment and ovariectomy (OVX), suggesting that the negative feedback response to estrogen is maintained in PE females. However, progesterone administration 2 days later failed to elicit a positive feedback response of gonadotropin secretion in PE females prior to LHRH-AG treatment, serum inhibin and 17 beta-estradiol (E2) concentrations were similar in middle-aged PE rats and young cyclic females on proestrus, while FSH levels were significantly greater in PE rats. After withdrawal of LHRH-AG treatment, plasma FSH concentrations remained elevated in PE rats as compared to young rats despite similar increases in E2. However, increases in plasma inhibin were delayed and significantly attenuated in PE rats.(ABSTRACT TRUNCATED AT 250 WORDS)


Assuntos
Estradiol/sangue , Estro/metabolismo , Regulação da Expressão Gênica/efeitos dos fármacos , Hormônio Liberador de Gonadotropina/análogos & derivados , Inibinas/sangue , Pamoato de Triptorrelina/análogos & derivados , Envelhecimento/fisiologia , Análise de Variância , Animais , Retroalimentação , Feminino , Hormônio Foliculoestimulante/sangue , Hormônio Liberador de Gonadotropina/farmacologia , Sistema Hipotálamo-Hipofisário/efeitos dos fármacos , Sistema Hipotálamo-Hipofisário/metabolismo , Hormônio Luteinizante/sangue , Ovariectomia , Ovário/anatomia & histologia , Ovário/metabolismo , Progesterona/farmacologia , Radioimunoensaio , Ratos , Ratos Endogâmicos
20.
Phys Rev Lett ; 68(17): 2616-2619, 1992 Apr 27.
Artigo em Inglês | MEDLINE | ID: mdl-10045444
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