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1.
Environ Res ; 226: 115667, 2023 06 01.
Artigo em Inglês | MEDLINE | ID: mdl-36906273

RESUMO

Due to the increasing impact of climate change, there is a need to examine the effect of environmental regulation on environmental quality. Consequently, we examine the nonlinear and mediation effects of environmental regulation on environmental quality using panel data of 45 major cities in the Yangtze River Economic Belt, China, from 2013 to 2020. Environmental regulation is divided into official and unofficial environmental regulations according to its formality. The results indicate that an increase of official and unofficial environmental regulations can promote the improvement of environmental quality. In fact, the positive effect of environmental regulation on cities with better environmental quality is greater than that of cities with poorer environmental quality. The implementation of both official and unofficial environmental regulations can improve environmental quality better than the single implementation of either official environmental regulation or unofficial environmental regulation. There are full mediation effects of Gross Domestic Product per capita and technological progress in the positive effects of official environmental regulation on environmental quality. There are also partial mediation effects of technological progress and industrial structure in the positive effects of unofficial environmental regulation on environmental quality. This study assesses the policy effectiveness of environmental regulation and determines the underlying mechanism between environmental regulation and environmental quality to provide a reference for other countries regarding environmental improvement.


Assuntos
Indústrias , Rios , Rios/química , Cidades , China , Produto Interno Bruto , Desenvolvimento Econômico
2.
J Phys Condens Matter ; 22(23): 236001, 2010 Jun 16.
Artigo em Inglês | MEDLINE | ID: mdl-21393773

RESUMO

Finite-temperature micromagnetics simulations are employed to study the magnetization-switching dynamics driven by a field applied at an angle to the long axis of an iron nanopillar. A bimodal distribution in the switching times is observed, and evidence for two competing modes of magnetization-switching dynamics is presented. For the conditions studied here, temperature T = 20.2 K and the reversal field 3260 Oe at an angle of 75° to the long axis, approximately 60% of the switches involve unstable decay (no free-energy barrier) and 40% involve metastable decay (a free-energy barrier is crossed). The latter are indistinguishable from switches that are constrained to start at a metastable free-energy minimum. Competition between unstable and metastable decay may not be confined to the temperature studied in this paper, and could greatly complicate applications involving magnetization switching near the coercive field.

3.
Artigo em Inglês | MEDLINE | ID: mdl-17598113

RESUMO

The absolute low-light sensitivity of four congeneric species of rockfish (genus Sebastes) was studied from analysis of electroretinograms measured in living fish. The purpose was: (1) to determine if temperature sensitive noise in rod photoreceptors affects the absolute limit to low-light sensitivity at environmentally realistic temperatures and light levels, and (2) to examine whether interspecific variations in habitat utilization within rockfish communities correlate with differences in visual sensitivity. It was found that the low-light sensitivity of individual retinae is inversely dependent on temperature, decreasing tenfold with a 10 degrees C increase in temperature. While in all four species, temperature had a similar effect on sensitivity, the absolute sensitivity levels were different. The four species could be divided into two groups based on measured sensitivity. Kelp and olive rockfish form a high-sensitivity group capable of responding to light levels approximately 50-fold lower than blue and black rockfish. The sensitivity groups correlated with reported diel activity patterns; the high-sensitivity group forages nocturnally, whereas members of the low-sensitivity group are quiescent during twilight and night and forage during the day.


Assuntos
Ecossistema , Peixes/fisiologia , Temperatura , Visão Ocular/fisiologia , Animais , Eletrorretinografia/veterinária , Fenômenos Fisiológicos Oculares , Limiar Sensorial/fisiologia , Especificidade da Espécie
4.
Eat Weight Disord ; 10(1): 25-32, 2005 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-15943169

RESUMO

A pilot assessment of a curriculum-based running program geared for girls 8-12 years old (n=322) was implemented to assess influences regarding psychological risk factors leading to disordered eating among girls who participate in sports. Utilizing a pretest/posttest study design, researchers administered questionnaires in pre-program session T(1), and post-program T(2). Statistical tests on self-esteem (t=-10.628, p<0.05), body size satisfaction (t=4.359, p<0.05), and eating attitudes/behaviors (t=4.806, p<0.05) revealed statistically significant improvements from baseline to post program. A sport-training program supplemented with a wellness curriculum may be an effective primary prevention program for disordered eating attitudes and behaviors.


Assuntos
Imagem Corporal , Currículo , Comportamento Alimentar , Satisfação Pessoal , Esportes , Adolescente , Fatores Etários , Criança , Feminino , Humanos , Avaliação de Programas e Projetos de Saúde , Corrida , Instituições Acadêmicas , Estados Unidos
5.
Chaos ; 15(4): 041106, 2005 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-16396582
6.
Eat Weight Disord ; 8(3): 231-7, 2003 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-14649788

RESUMO

Self-esteem, dieting, and body image of 131 female beauty pageant contestants (mean age 26.0 years) from 43 states were examined by an anonymous survey. Most (89.6%) reported being a pageant finalist or winner and 55.2% had competed at the nationa/international level Over one-fourth (26%) of the women had been told or perceived they had an eating disorder which reportedly began at 16.25 years. Almost half (48.5%) reported wanting to be thinner and 57% were trying to lose weight. Higher self-esteem scores were significantly associated with increased level of competition (i.e.: from local to international pageants), but not with the number of times the women were pageant finalists or winners. Future study is warranted to determine how pageant participation influences self-esteem, body image, and the development of eating disorders.


Assuntos
Indústria da Beleza , Imagem Corporal , Comportamento Competitivo , Transtornos da Alimentação e da Ingestão de Alimentos/psicologia , Autoimagem , Mulheres/psicologia , Adolescente , Adulto , Atitude Frente a Saúde , Indústria da Beleza/métodos , Constituição Corporal , Índice de Massa Corporal , Dieta Redutora/psicologia , Transtornos da Alimentação e da Ingestão de Alimentos/epidemiologia , Transtornos da Alimentação e da Ingestão de Alimentos/terapia , Feminino , Identidade de Gênero , Humanos , Obesidade/epidemiologia , Obesidade/prevenção & controle , Obesidade/psicologia , Prevalência , Fatores de Risco , Autocuidado/métodos , Autocuidado/psicologia , Valores Sociais , Inquéritos e Questionários , Magreza/epidemiologia , Magreza/psicologia , Estados Unidos/epidemiologia , Redução de Peso
7.
J Prosthodont ; 10(3): 154-9, 2001 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-11641843

RESUMO

PURPOSE: This study investigated the effects of implant proximity on inter-implant bone height, density, and osseointegration using digital radiography and histology. MATERIALS AND METHODS: After a feasibility study, a total of 80 endosteal implants were placed in 20 New Zealand White Rabbit tibias. With the aid of a surgical jig, four 8.5-mm implants were placed in the medial aspect of the tibial crest at inter-implant distances of approximately 1, 1.5, and 3 mm. Standardized digital radiographs using a paralleling device were made immediately after placement of implants. Implants were allowed to osseointegrate for 90 days. After this healing period, the animals were sacrificed, and the standardized radiographs were repeated. The tibias were harvested, processed, and invested in epoxy. Sagittal sections were made from each specimen for histologic evaluation. The initial and postmortem digital radiographs were evaluated for inter-implant distances, vertical bone height changes over time and between implant pairs, and bone density changes over time and between implant pairs using a computer image analysis program and computer statistics program. RESULTS: The actual inter-implant distances were consistent in a range of 0.2 mm. Bone height increased significantly from presurgical levels at all 3 locations (p < .0005). Repeated measures analysis of variance comparing change in bone height at the 3 implant pair distances showed significant differences among the 3 (p = .002). Paired t tests showed that the amount of bone growth at the 1-mm separation site was significantly greater than the 1.5-mm site (p = .026) and the 3-mm site (p = .001), whereas bone growth at the 1.5- and 3-mm sites did not show significant differences (p = .162). A repeated measures analysis of variance comparing change in bone density showed no significant differences (p > .05) among the 3 inter-implant distances for either the 8-mm position (approximately crestal bone height) or the 6-mm position (approximately 2 mm subcrestal). CONCLUSION: Within the limits of this study, it seems placing implants closely together does not adversely affect bone height or density. Conversely, it seems that placing implants closer together may increase bone growth.


Assuntos
Osso e Ossos/cirurgia , Implantação Dentária Endóssea/métodos , Implantes Dentários , Análise de Variância , Animais , Densidade Óssea , Osso e Ossos/diagnóstico por imagem , Osso e Ossos/patologia , Osso e Ossos/fisiopatologia , Resinas Epóxi , Estudos de Viabilidade , Processamento de Imagem Assistida por Computador , Modelos Animais , Osseointegração , Osteogênese/fisiologia , Projetos Piloto , Inclusão em Plástico , Coelhos , Intensificação de Imagem Radiográfica , Estatística como Assunto , Tíbia , Cicatrização
8.
Nature ; 406(6796): 633-6, 2000 Aug 10.
Artigo em Inglês | MEDLINE | ID: mdl-10949304

RESUMO

The early steps that lead to the rise in calcium and egg activation at fertilization are unknown but of great interest--particularly with the advent of in vitro fertilization techniques for treating male infertility and whole-animal cloning by nuclear transfer. This calcium rise is required for egg activation and the subsequent events of development in eggs of all species. Injection of intact sperm or sperm extracts can activate eggs, suggesting that sperm-derived factors may be involved. Here we show that nitric oxide synthase is present at high concentration and active in sperm after activation by the acrosome reaction. An increase in nitrosation within eggs is evident seconds after insemination and precedes the calcium pulse of fertilization. Microinjection of nitric oxide donors or recombinant nitric oxide synthase recapitulates events of egg activation, whereas prior injection of oxyhaemoglobin, a physiological nitric oxide scavenger, prevents egg activation after fertilization. We conclude that nitric oxide synthase and nitric-oxide-related bioactivity satisfy the primary criteria of an egg activator: they are present in an appropriate place, active at an appropriate time, and are necessary and sufficient for successful fertilization.


Assuntos
Fertilização/fisiologia , Óxido Nítrico/fisiologia , Óvulo/fisiologia , Reação Acrossômica , Animais , Feminino , Masculino , Óxido Nítrico Sintase/metabolismo , Ouriços-do-Mar , Espermatozoides/enzimologia , Espermatozoides/fisiologia
9.
Women Health ; 30(3): 77-92, 2000.
Artigo em Inglês | MEDLINE | ID: mdl-10943804

RESUMO

Black (27%) and White (73%) women (n = 215) completed a survey assessing weight concern, ideal body size beliefs, body dissatisfaction, attitudes toward overweight body size, and parental criticism of their childhood appearance. Sixty-four percent of the women reported they were currently trying to lose weight and 63% desired a body size thinner than their own. High weight concern and negative attitudes toward overweight persons were reported, respectively, by 45% and 17%, of the women. The only significant difference found by race was weight concern as White women rated this significantly higher than Black women. No significant frequencies of choice were associated with the women's socioeconomic level. Self-reported ratings of weight concern were significant and positively associated with those for body dissatisfaction, negative attitudes toward overweight persons, negative attitudes toward one's own overweight, and criticism of childhood appearance by mothers or fathers.


Assuntos
Atitude/etnologia , Negro ou Afro-Americano/psicologia , Imagem Corporal , Obesidade/psicologia , Relações Pais-Filho , População Branca/psicologia , Adulto , Criança , Feminino , Humanos , Masculino , South Carolina/etnologia , Inquéritos e Questionários , Saúde da Mulher
10.
Ethn Health ; 5(1): 79-94, 2000 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-10858942

RESUMO

OBJECTIVE: The purpose of this study was to assess grade, race, socioeconomic status and gender differences in perceptions of body size, weight concerns, and weight control practices between 4th and 7th grade students in South Carolina. DESIGN: Two random samples, consisting of a total of 1,597 children (53.1% white, 51.97% female, 44.9% 4th graders) participated in two questionnaire surveys. Both surveys included a series of seven female and seven male body size drawings, body image and weight concern questions, and questions pertaining to weight control practices. Responses to the questionnaire were analyzed using chi-square analysis and the General Linear Model. RESULTS: Using socioeconomic status (SES), race, gender, and grade as independent variables, differences in ideal adult body size, opposite gender ideal adult body size, weight concerns, perceptions of family/peer weight concerns, perceptions of own body size and weight control practices were studied. Analyses revealed that 4th grade males select a larger ideal adult body size and opposite gender ideal adult body size when compared to 7th grade males (p < 0.0001 and p = 0.0078, respectively). Fourth grade females indicated less personal concern about their weight than 7th grade females (p = 0.0009). Fourth graders also perceived less family/peer concern about weight than 7th graders (p = 0.0027) and 7th graders described themselves as being more overweight than 4th graders (p = 0.0039). Blacks selected a significantly larger body size than white children for ideal adult (p = 0.0287) and ideal opposite gender adult body size (p < 0.0001 for males, p = 0.0030 for females). Blacks also perceived less personal and family/peer concern about weight when compared to whites (p = 0.0083). More whites reported that they were trying to lose weight, as compared to blacks (p = 0.0010). Males also selected significantly larger body size silhouettes than females for ideal adult body size (p = 0.0012). Males expressed less personal concern about weight (p < 0.0001), perceived less family/peer concern about weight (p < 0.0001), and were less likely than females to be engaged in weight loss (p < 0.0001). Females in the high SES category selected a significantly smaller ideal male adult body size than females in the low SES group (p = 0.0124) and more females in the high SES category were trying to lose weight when compared to females in the low SES group (p = 0.0055). CONCLUSION: This study indicates that early in a child's sociocultural development, grade level, gender, race, and SES are influential in the perception of ideal adult body size and opposite gender ideal adult body size. These factors are also influential in determining concerns about weight and weight control practices. The findings of this study support the need to begin health and wellness education efforts early in childhood while taking into account racial, gender, age, and SES disparities. This knowledge can also be useful in targeting interventions for both obesity and eating disorders.


Assuntos
Imagem Corporal , Peso Corporal , Adolescente , Adulto , Negro ou Afro-Americano , Criança , Estudos Transversais , Feminino , Humanos , Masculino , Classe Social , South Carolina , Redução de Peso , População Branca
11.
J Periodontol ; 71(3): 504-9, 2000 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-10776941

RESUMO

BACKGROUND: We describe an unusual case of extra-nodal non-Hodgkin's lymphoma that developed in the maxillae associated with localized severe periodontitis in a 64-year-old Caucasian male. The lymphoma was diagnosed less than 2 years following routine periodontal surgery and 8 weeks after the extraction of hopeless teeth in the associated area. METHODS: Two months following the extractions, the patient experienced pain and swelling in the maxillary right edentulous area mimicking an abscess, and reported for emergency care. An expansile lesion measuring 2.0 x 2.5 cm in diameter was noted on radiographic examination to extend into the right maxillary sinus. A definitive biopsy diagnosis of high-grade, small, non-cleaved, diffuse non-Hodgkin's lymphoma of the right posterior maxillae was established. The patient was subsequently treated by a combination of radiation, chemotherapy, and bone marrow transplantation. RESULTS: The maxillary tissues healed uneventfully, and the patient has been closely observed for approximately 5 years without symptoms or recurrence of the lymphoma. CONCLUSIONS: This case highlights the need for careful debridement of extraction sockets associated with severe periodontitis and argues for the routine submission of extracted teeth with adjacent soft tissue for microscopic analysis, to assist in the early diagnosis of potentially life-threatening malignancies.


Assuntos
Linfoma não Hodgkin/complicações , Neoplasias do Seio Maxilar/complicações , Periodontite/etiologia , Biópsia , Terapia Combinada , Diagnóstico Diferencial , Seguimentos , Humanos , Masculino , Pessoa de Meia-Idade , Abscesso Periodontal/diagnóstico
12.
J Gen Physiol ; 110(2): 155-64, 1997 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-9236208

RESUMO

The stimulation of IP3 production by muscarinic agonists causes both intracellular Ca2+ release and activation of a voltage-independent cation current in differentiated N1E-115 cells, a neuroblastoma cell line derived from mouse sympathetic ganglia. Earlier work showed that the membrane current requires an increase in 3',5'-cyclic guanosine monophosphate (cGMP) produced through the NO-synthase/guanylyl cyclase cascade and suggested that the cells may express cyclic nucleotide-gated ion channels. This was tested using patch clamp methods. The membrane permeable cGMP analogue, 8-br-cGMP, activates Na+ permeable channels in cell attached patches. Single channel currents were recorded in excised patches bathed in symmetrical Na+ solutions. cGMP-dependent single channel activity consists of prolonged bursts of rapid openings and closings that continue without desensitization. The rate of occurrence of bursts as well as the burst length increase with cGMP concentration. The unitary conductance in symmetrical 160 mM Na+ is 47 pS and is independent of voltage in the range -50 to +50 mV. There is no apparent effect of voltage on opening probability. The dose response curve relating cGMP concentration to channel opening probability is fit by the Hill equation assuming an apparent KD of 10 microm and a Hill coefficient of 2. In contrast, cAMP failed to activate the channel at concentrations as high as 100 microm. Cyclic nucleotide gated (CNG) channels in N1E-115 cells share a number of properties with CNG channels in sensory receptors. Their presence in neuronal cells provides a mechanism by which activation of the NO/cGMP pathway by G-protein-coupled neurotransmitter receptors can directly modify Ca2+ influx and electrical excitability. In N1E-115 cells, Ca2+ entry by this pathway is necessary to refill the IP3-sensitive intracellular Ca2+ pool during repeated stimulation and CNG channels may play a similar role in other neurons.


Assuntos
GMP Cíclico/fisiologia , Ativação do Canal Iônico/fisiologia , Neurônios/fisiologia , Sistema Nervoso Simpático/fisiologia , 8-Bromo Monofosfato de Adenosina Cíclica/farmacologia , Animais , Encéfalo/citologia , Encéfalo/efeitos dos fármacos , Química Encefálica/efeitos dos fármacos , Química Encefálica/fisiologia , Neoplasias Encefálicas/metabolismo , Linhagem Celular , GMP Cíclico/análogos & derivados , GMP Cíclico/farmacologia , Gânglios Simpáticos/citologia , Gânglios Simpáticos/efeitos dos fármacos , Gânglios Simpáticos/metabolismo , Ativação do Canal Iônico/efeitos dos fármacos , Potenciais da Membrana/efeitos dos fármacos , Potenciais da Membrana/fisiologia , Camundongos , Neuroblastoma/metabolismo , Neurônios/efeitos dos fármacos , Técnicas de Patch-Clamp , Canais de Sódio/efeitos dos fármacos , Canais de Sódio/metabolismo , Sistema Nervoso Simpático/citologia , Sistema Nervoso Simpático/efeitos dos fármacos
13.
Am J Physiol ; 273(2 Pt 1): C612-7, 1997 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-9277358

RESUMO

Fura 2 imaging was used to measure intracellular Ca2+ signals in N1E-115 mouse neuroblastoma cells during combined activation of bradykinin (BK) and cholinergic receptors. BK and carbachol (CCh) both activate phospholipase C (PLC) and cause Ca2+ release from inositol 1,4,5-trisphosphate (IP3)-sensitive Ca2+ stores. The Ca2+ signal in response to CCh is prolonged by the activation of Ca2+ influx, but BK does not appear to activate the influx pathway. When BK and CCh are applied together (BK+CCh), the Ca2+ response is composed of both Ca2+ release and Ca2+ influx. Ca2+ influx is also activated by BK+CCh in a subset of cells that does not respond with a intracellular Ca2+ concentration increase when CCh is presented by itself. This suggests that CCh stimulates a Ca(2+)-silent cholinergic receptor that is not coupled to Ca2+ release but acts synergistically with BK receptors to activate Ca2+ influx. Pertussis toxin reduces influx without affecting release, indicating that the G protein that modulates the influx pathway is different from the G protein responsible for activating PLC. Cholinergic stimulation also causes progressive heterologous desensitization of BK-evoked Ca2+ release. Desensitization has the unique property of continuing to develop after the cholinergic agonist is removed and the cholinergic Ca2+ response has fully recovered. Heterologous desensitization is not the result of Ca2+ store depletion or a long-lasting inhibition of PLC or IP3-dependent Ca2+ release. Instead, it appears to involve an early step in the BK-signaling cascade, possibly at the level of the B2 receptor or associated G proteins.


Assuntos
Bradicinina/farmacologia , Cálcio/metabolismo , Agonistas Colinérgicos/farmacologia , Neuroblastoma/metabolismo , Animais , Carbacol/farmacologia , Camundongos , Agonistas Muscarínicos/farmacologia , Neuroblastoma/patologia , Toxina Pertussis , Receptores Colinérgicos/metabolismo , Transdução de Sinais , Células Tumorais Cultivadas , Fatores de Virulência de Bordetella/farmacologia
14.
Int J Eat Disord ; 21(3): 279-84, 1997 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-9097201

RESUMO

OBJECTIVE: The purpose of this study was to assess racial and gender differences in perceptions of ideal body size among White and Black fourth-grade children. METHOD: A random sample of 817 children (51.4% female, 51.8% White, and mean age 9 years) participated in a body image and weight concern survey. RESULTS: Using socioeconomic status (SES), race, and gender as independent variables, Black children selected significantly heavier ideal sizes than White children for self, male child, female child, adult male, and adult female. Although almost one half (46%) of Black females wanted to be thinner than their current size, their body size selections were significantly larger than those of White females. Black and White males differed only in the selections of ideal-female child and adult sizes. Cross-gender comparisons indicated females and Whites experience more body dissatisfaction and weight concern than males and Blacks. DISCUSSION: Our study indicates that early in the sociocultural development of children, gender, race, and SES are influential factors in selecting ideal body size and determining body satisfaction.


Assuntos
Constituição Corporal , Peso Corporal , Negro ou Afro-Americano/psicologia , Imagem Corporal , Peso Corporal/etnologia , Criança , Feminino , Humanos , Masculino , Autoimagem , Caracteres Sexuais , Fatores Socioeconômicos , População Branca/psicologia
15.
J Periodontol ; 67(10): 1011-5, 1996 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-8910841

RESUMO

A pyogenic granuloma is an exuberant growth of granulation tissue secondary to irritation. Intraorally, it can present with a wide array of clinical appearances, ranging from a sessile lesion to an elevated mass. Pyogenic granulomas generally are soft, painless, and deep red to reddish-purple in color. They are usually 0.5 to 1.0 cm in diameter, more common in females, and often found on the keratinized tissue. This case is interesting because the pyogenic granuloma was found associated with guided tissue regeneration and the lingual alveolar mucosa. The lesion arose after demineralized freeze dried bone allograft and an expanded polytetrafluoroethylene (ePTFE) membrane were utilized to repair osseous defects. Five weeks after surgery, the patient presented for routine follow-up where suppuration associated with the membrane was noted along with an exophytic growth of the lingual alveolar mucosa. The ePTFE membrane was removed alone with an excisional biopsy of one of the growths. By 10 days after the removal of ePTFE, the lesion spontaneously healed. Histologic evaluation of the tissue was consistent with a pyogenic granuloma. This is the first case in the literature of a pyogenic granuloma associated with a routine guided tissue regenerative surgery using a non-resorbable membrane and allograft.


Assuntos
Granuloma Piogênico/etiologia , Regeneração Tecidual Guiada Periodontal/efeitos adversos , Doenças da Boca/etiologia , Adulto , Perda do Osso Alveolar/cirurgia , Biópsia , Transplante Ósseo , Técnica de Descalcificação , Seguimentos , Liofilização , Tecido de Granulação/patologia , Granuloma Piogênico/patologia , Humanos , Masculino , Membranas Artificiais , Doenças da Boca/patologia , Mucosa Bucal/patologia , Pigmentação , Politetrafluoretileno , Supuração , Preservação de Tecido
16.
Cell Calcium ; 19(5): 399-407, 1996 May.
Artigo em Inglês | MEDLINE | ID: mdl-8793180

RESUMO

Fura-2 fluorescence imaging was used to measure changes in intracellular Ca2+ concentration in individual N1E-115 neuroblastoma cells during repeated activation of M1 muscarinic receptors with carbachol. Ca2+ transients could be elicited repeatedly at 4 min intervals with little decrement as long as external Ca2+ was present. When the cells were bathed in Ca(2+)-free saline, however, the response amplitude decreased rapidly in a use-dependent fashion, indicating that external Ca2+, and presumably Ca2+ influx, is required for refilling Ca2+ stores during the interval between trials. The response amplitude also decreased during repeated stimulation in cells treated with the NO-synthase inhibitor L-NMMA or with the guanylyl cyclase inhibitor LY-83583 even when Ca2+ was present. Application of the membrane permeable cGMP analog 8-Br-cGMP reversed the effect of L-NMMA and promoted refilling in the continued presence of NO-synthase inhibitor. These results indicate that activation of the NO/cGMP pathway is necessary for refilling Ca2+ stores during muscarinic signaling. Evidence is also presented suggesting that the NO/cGMP pathway is involved in long term modulation of the content of Ca2+ stores.


Assuntos
Cálcio/metabolismo , Guanosina Monofosfato/metabolismo , Neuroblastoma/metabolismo , Óxido Nítrico/metabolismo , Transdução de Sinais/efeitos dos fármacos , Animais , Inibidores Enzimáticos/farmacologia , Camundongos , Óxido Nítrico Sintase/antagonistas & inibidores , Sistema Nervoso Simpático/patologia , Células Tumorais Cultivadas , ômega-N-Metilarginina/farmacologia
17.
J Sch Health ; 66(3): 112-8, 1996 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-8857160

RESUMO

A stratified, random sample of 344 White and Black adolescent females participated in a survey of ideal body size beliefs, which included responses to a questionnaire and a series of nine female and male body size drawings. Using SES and race as independent variables and BMI (kg/m2) as a covariate. Black females preferred a significantly heavier ideal female body size than Whites. They also perceived their parents and both male and female friends would select as ideal a significantly heavier female body size than White subjects. Black subjects' body size preferences were significantly more influenced by family members than were White subjects, who were significantly more influenced by their peer group. These findings suggest a greater social approval of increasing weight and body size for Black adolescent females, a desire for a smaller size by White adolescent females, and cultural differences in the influencing factors that help to communicate these body size preferences.


Assuntos
Negro ou Afro-Americano/psicologia , Constituição Corporal , Imagem Corporal , População Branca/psicologia , Adolescente , Negro ou Afro-Americano/estatística & dados numéricos , Intervalos de Confiança , Características Culturais , Feminino , Humanos , Razão de Chances , Distribuição Aleatória , Reprodutibilidade dos Testes , South Carolina , Inquéritos e Questionários , População Branca/estatística & dados numéricos
18.
J Neurosci ; 16(5): 1702-9, 1996 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-8774438

RESUMO

Inward currents activated by 8-bromc-cGMP and by muscarinic agonist were compared in N1E-115 mouse neuroblastoma cells using perforated-patch voltage clamp and Fura-2 imaging. The cGMP analog activates a voltage-independent inward current that is carried at least in part by Ca2+ because it persists in Na(+)-free saline when Ca2+ is present and is blocked by external Mn2+ and Ba2+. The current is similar to the inward current that develops during stimulation of M1 muscarinic receptors, and the currents activated by agonist and by 8-bromo-cGMP are not additive, indicating that the same pathway is involved. Inhibition of cGMP production with NG-monomethyl-L-arginine (L-NMMA), a competitive inhibitor of nitric oxide (NO)-synthase, prevents activation of Ca2+ current by agonist without affecting the content of intracellular Ca2+ stores or the ability of agonist to mobilize Ca2+. The inhibition is overcome by 8-bromo-cGMP. LY83583, a competitive inhibitor of guanylyl cyclase, reversibly blocks activation of Ca2+ current by agonist, again without affecting the content of Ca2+ stores or Ca2+ release. Rp-8-pCPT-cGMPS, an inhibitory analog of cGMP, also reduces the Ca2+ current and reduces Ca2+ influx during muscarinic activation. It is concluded that cGMP is the necessary and sufficient intermediate in the pathway linking muscarinic receptor occupancy to the activation of voltage-independent Ca2+ current. The pathway involves positive feedback. Calcium entering via voltage-independent channels preferentially stimulates NO-synthase, which leads to enhanced cGMP production and greater Ca2+ influx. Positive feedback may explain the rapid increase in cGMP that occurs during muscarinic receptor activation.


Assuntos
Cálcio/metabolismo , GMP Cíclico/metabolismo , Óxido Nítrico/metabolismo , Receptores Muscarínicos/metabolismo , Animais , GMP Cíclico/análogos & derivados , GMP Cíclico/farmacologia , Guanilato Ciclase/antagonistas & inibidores , Camundongos , Agonistas Muscarínicos/farmacologia , Óxido Nítrico Sintase/antagonistas & inibidores , Tionucleotídeos/farmacologia , Células Tumorais Cultivadas
19.
J Gen Physiol ; 106(5): 975-93, 1995 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-8648300

RESUMO

The relationship between the depletion of IP3-releasable intracellular Ca2+ stores and the activation of Ca(2+)-selective membrane current was determined during the stimulation of M1 muscarinic receptors in N1E-115 neuroblastoma cells. External Ca2+ is required for refilling Ca2+ stores and the voltage-independent, receptor-regulated Ca2+ current represents a significant Ca2+ source for refilling. The time course of Ca2+ store depletion was measured with fura-2 fluorescence imaging, and it was compared with the time course of Ca2+ current activation measured with nystatin patch voltage clamp. At the time of maximum current density (0.18 + .03 pA/pF; n = 48), the Ca2+ content of the IP3-releasable Ca2+ pool is reduced to 39 + 3% (n = 10) of its resting value. Calcium stores deplete rapidly, reaching a minimum Ca2+ content in 15-30 s. The activation of Ca2+ current is delayed by 10-15 s after the beginning of Ca2+ release and continues to gradually increase for nearly 60 s, long after Ca2+ release has peaked and subsided. The delay in the appearance of the current is consistent with the idea that the production and accumulation of a second messenger is the rate-limiting step in current activation. The time course of Ca2+ store depletion was also measured after adding thapsigargin to block intracellular Ca2+ ATPase. After 15 min in thapsigargin, IP3-releasable Ca2+ stores are depleted by > 90% and the Ca2+ current is maximal (0.19 + 0.05 pA/pF; n = 6). Intracellular loading with the Ca2+ buffer EGTA/AM (10 microM; 30 min) depletes IP3-releasable Ca2+ stores by between 25 and 50%, and it activates a voltage-independent inward current with properties similar to the current activated by agonist or thapsigargin. The current density after EGTA/AM loading (0.61 + 0.32 pA/pF; n = 4) is three times greater than the current density in response to agonist or thapsigargin. This could result from partial removal of Ca(2+)-dependent inactivation.


Assuntos
Cálcio/deficiência , Cálcio/metabolismo , Receptores Muscarínicos/fisiologia , Animais , Canais de Cálcio/efeitos dos fármacos , Canais de Cálcio/metabolismo , Carbacol/farmacologia , Quelantes/farmacologia , Ácido Egtázico/farmacologia , Eletrofisiologia , Inibidores Enzimáticos/farmacologia , Gânglios Simpáticos/citologia , Inositol 1,4,5-Trifosfato/fisiologia , Camundongos , Agonistas Muscarínicos/farmacologia , Neuroblastoma , Neurônios/química , Neurônios/metabolismo , Sistemas do Segundo Mensageiro/fisiologia , Terpenos/farmacologia , Tapsigargina , Células Tumorais Cultivadas/química , Células Tumorais Cultivadas/citologia , Células Tumorais Cultivadas/metabolismo
20.
Biophys J ; 69(5): 1683-97, 1995 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-8580312

RESUMO

In many types of eukaryotic cells, the activation of surface receptors leads to the production of inositol 1,4,5-trisphosphate and calcium release from intracellular stores. Calcium release can occur in complex spatial patterns, including waves of release that traverse the cytoplasm. Fluorescence video microscopy was used to view calcium waves in single mouse neuroblastoma cells. The propagation of calcium waves was slowed by buffers that bind calcium quickly, such as BAPTA, but not by a buffer with slower on-rate, EGTA. This shows that a key feedback event in wave propagation is rapid diffusion of calcium occurring locally on a scale of < 1 micron. The length-speed product of wavefronts was used to determine that calcium acting in feedback diffuses at nearly the rate expected for free diffusion in aqueous solution. In cytoplasm, which contains immobile Ca2+ buffers, this rate of diffusion occurs only in the first 0.2 ms after release, within 0.4 micron of a Ca2+ release channel mouth. Calcium diffusion from an open channel to neighboring release sites is, therefore, a rate-determining regenerative step in calcium wave propagation. The theoretical limitations of the wave front analysis are discussed.


Assuntos
Cálcio/metabolismo , Animais , Fenômenos Biofísicos , Biofísica , Soluções Tampão , Canais de Cálcio/efeitos dos fármacos , Canais de Cálcio/metabolismo , Quelantes/farmacologia , Ácido Egtázico/análogos & derivados , Ácido Egtázico/farmacologia , Retroalimentação , Inositol 1,4,5-Trifosfato/metabolismo , Líquido Intracelular/metabolismo , Transporte de Íons/efeitos dos fármacos , Cinética , Camundongos , Microscopia de Fluorescência , Microscopia de Vídeo , Modelos Biológicos , Transdução de Sinais/efeitos dos fármacos , Células Tumorais Cultivadas
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