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1.
Neotrop Entomol ; 49(6): 783-794, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-32462421

RESUMO

Insects are the most abundant and diverse organisms on Earth and provide essential ecosystem services. However, Brazilian society rarely consider the importance of insects in their diverse country. Therefore, in this review, we provide an overview of ecosystem services provided by insects in Brazil. A database search returned 136 articles, published in English or Portuguese, on ecosystem services provided by insects in Brazil. The first article was published in 1982, and majority of the studies were conducted in the Atlantic Forest or the Cerrado biomes. The most frequently studied insect-provided ecosystem services were pollination, decomposition, and biological control of pests. The studies focused primarily on natural and anthropic ecosystems, and most followed an experimental approach. We noted that the term "ecosystem services" was not used frequently in studies on insects in Brazil. The information available was mostly taxon-biased. We discuss the implications of these findings in relation to reconciling economic interests and the need for insect conservation for continued provision of ecosystem services in a broader perspective. In conclusion, we argue that the scientific community should focus on understanding the ecosystem services provided by insects other than those strictly related to economic activities, and on improving communication with policymakers and citizens. As a tropical and megadiverse country, Brazil has the potential to become a protagonist in conserving and using the ecosystem services provided by insects, both locally and internationally, by providing scientific information to policymakers and citizens.


Assuntos
Ecossistema , Insetos , Polinização , Animais , Biodiversidade , Brasil , Conservação dos Recursos Naturais
2.
Neotrop Entomol ; 48(2): 175-185, 2019 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-30847779

RESUMO

Brazil is one of the main users of chemical pesticides in the world. These products threaten human and environmental health, and many of them are prohibited in countries other than Brazil. This paradigm exists in contrast with worldwide efforts to make the need for food production compatible with biodiversity conservation, preservation of ecosystem services, and human health. In this scenario, the development of sustainable methods for crop production and pest management such as organic agriculture and biological control are necessary. Herein, we describe how the process of registration of natural enemy-based products in organic agriculture is simpler and faster than the conventional route of chemical insecticides and can favor the development of the biological control market in Brazil. Since the regulatory mechanisms have been established in Brazil for organic agriculture, the number of biological control products registered has increased exponentially. Today, 50 companies and associations are marketing 16 species/isolates and 95 natural enemy-based products. Although this scenario presents a series of new opportunities to increase and stimulate a more sustainable agriculture in the country, biological control is not always aligned with the aims and philosophy of organic agriculture and agroecology. Therefore, we also argue that new research efforts are needed on understanding how conservation biological control strategies can be integrated with augmentation biological control to promote a sustainable agriculture under the concepts of organic agriculture and agroecology.


Assuntos
Agentes de Controle Biológico , Agricultura Orgânica/legislação & jurisprudência , Controle Biológico de Vetores/legislação & jurisprudência , Brasil , Conservação dos Recursos Naturais , Praguicidas
3.
Int J Hyperthermia ; 34(7): 994-1001, 2018 11.
Artigo em Inglês | MEDLINE | ID: mdl-29747544

RESUMO

PURPOSE: Radiotherapy (RT) treatment of locally-advanced and recurrent head and neck carcinoma (HNC) results in disappointing outcomes. Combination of RT with cisplatin or cetuximab improves survival but the increased toxicity and patient's comorbidity warrant the need for a less-toxic radiosensitizer. Stimulated by several randomized studies demonstrating the radio-sensitizing effect of hyperthermia, we developed the HYPERcollar. Here, we report early experience and toxicity in patients with advanced HNC. METHODS AND MATERIALS: 119 hyperthermia treatments given to 27 patients were analyzed. Hyperthermia was applied once a week by the HYPERcollar aimed at achieving 39-43 °C in the target area, up to patients' tolerance. Pre-treatment planning was used to optimize treatment settings. When possible, invasive thermometry catheters were placed. RESULTS: Mean power applied during the 119 hyperthermia treatments ranged from 120 to 1007 W (median 543 W). 15 (13%) hyperthermia treatments were not fully completed due to: pain allocated to hyperthermia (6/15), dyspnea from sticky saliva associated with irradiation (2/15) and unknown reasons (7/15). No severe complications or enhanced thermal or mucosal toxicities were observed. Excluding post-operative treatment, response rates after 3 months were 46% (complete) and 7% (partial). CONCLUSION: Hyperthermia with the HYPERcollar proved to be safe and feasible with good compliance and promising outcome.


Assuntos
Neoplasias de Cabeça e Pescoço/radioterapia , Neoplasias de Cabeça e Pescoço/terapia , Hipertermia Induzida/métodos , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Estudos de Viabilidade , Feminino , Neoplasias de Cabeça e Pescoço/patologia , Humanos , Masculino , Pessoa de Meia-Idade , Adulto Jovem
4.
Neotrop Entomol ; 44(5): 528-32, 2015 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-26123056

RESUMO

Current knowledge on coccinellids is primarily focused on their role as natural enemies of soft-bodied insects. However, there is a great diversity of coccinellid parasitoid species that are less studied. Here, we describe new records of coccinellid parasitoids with emphasis on new host-parasitoid interactions in 11 sample sites in Brazil. We collected 122 coccinellid individuals parasitized by six species of parasitoids in the Cerrado and in the Atlantic Rainforest biomes. New records of coccinellid parasitoids and host associations, expansion of habitat ranges and interactions are discussed focusing on the lack of basic information on these interactions in Brazil.


Assuntos
Besouros/classificação , Interações Hospedeiro-Parasita , Insetos/parasitologia , Animais , Brasil , Ecossistema
5.
Neotrop Entomol ; 42(1): 102-11, 2013 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-23949719

RESUMO

Bt cotton plants expressing Cry1Ac protein have high specificity for the control of lepidopteran larvae. However, studies conducted in several countries have shown these plants have a differential impact on nontarget herbivores. The aim of this study was to compare the colonization rates and population abundance of the cotton aphid, Aphis gossypii Glover (Hemiptera: Aphididae) and the boll weevil, Anthonomus grandis Boheman (Coleoptera: Curculionidae), in plots of Bt (Nuopal) and non-Bt cotton (Delta Opal) in an experimental field in Brasilia, DF, Brazil. No difference was observed in the preference and colonization by winged aphids to plants from the two treatments. There was no significant difference in abundance of wingless aphids or in the production of winged aphids between treatments. Apparently, the parameters that control factors such as fecundity, survival, and dispersal were similar on both Bt and non-Bt plants. Monitoring of plants for coccinellids, a specialist predator of aphids, and ants that act on the dispersal of aphids among plants showed no significant difference between Bt and non-Bt plants, supporting the inference above. Regarding the effect on boll weevil, there was also no significant difference between treatments in the total number of fruiting structures attacked in each plot, the percentage of fruiting structures attacked per plant or on the number of weevils emerging from fruits with boll weevil damage from egg-laying, when damaged fruit samples were held in the laboratory. Based on these results, we conclude that there is no impact of Bt cotton crop expressing Cry1Ac on the nontarget herbivores tested under field conditions.


Assuntos
Distribuição Animal , Afídeos/fisiologia , Gossypium/parasitologia , Gorgulhos/fisiologia , Animais , Toxinas de Bacillus thuringiensis , Proteínas de Bactérias/biossíntese , Brasil , Endotoxinas/biossíntese , Gossypium/metabolismo , Proteínas Hemolisinas/biossíntese , Plantas Geneticamente Modificadas/metabolismo
6.
Phys Med Biol ; 58(17): 5997-6009, 2013 Sep 07.
Artigo em Inglês | MEDLINE | ID: mdl-23938760

RESUMO

Accumulating evidence shows that hyperthermia improves head-and-neck cancer treatment. Over the last decade, we introduced a radiofrequency applicator, named HYPERcollar, which enables local heating also of deep locations in this region. Based on clinical experience, we redesigned the HYPERcollar for improved comfort, reproducibility and operator handling. In the current study, we analyze the redesign from an electromagnetic point of view. We show that a higher number of antennas and their repositioning allow for a substantially improved treatment quality. Combined with the much better reproducibility of the water bolus, this will substantially minimize the risk of underexposure. All improvements combined enable a reduction of hot-spot prominence (hot-spot to target SAR quotient) by 32% at an average of 981 W, which drastically reduces the probability for system power to become a treatment limiting source. Moreover, the power deposited in the target selectively can be increased by more than twofold. Hence, we expect that the HYPERcollar redesign currently under construction allows us to double the clinically applied power to the target while reducing the hot-spots, resulting in higher temperatures and, consequently, better clinical outcome.


Assuntos
Fenômenos Eletromagnéticos , Neoplasias de Cabeça e Pescoço/terapia , Hipertermia Induzida/instrumentação , Terapia por Radiofrequência , Desenho de Equipamento , Neoplasias de Cabeça e Pescoço/radioterapia , Humanos
7.
Arq. Inst. Biol. (Online) ; 77(4): 669-676, out.-dez. 2010. tab, graf
Artigo em Português | VETINDEX, LILACS | ID: biblio-1395470

RESUMO

A adoção de práticas culturais como o consórcio de culturas e o tipo de irrigação podem beneficiar a comunidade de inimigos naturais no agroecossistema ao disponibilizar micro-habitas mais favoráveis e recursos alternativos, principalmente em períodos de baixa precipitação pluviométrica. O objetivo deste trabalho foi avaliar como o consórcio tomate + coentro e o tipo de irrigação (gotejamento e aspersão) podem beneficiar a comunidade de inimigos naturais no agroecossistema do tomateiro. O trabalho foi realizado no campo experimental da Embrapa Hortaliças, Gama, DF, de setembro a novembro de 2008. Os tomateiros foram plantados em monocultura ou consorciados com o coentro e irrigados por gotejamento e por aspersão (três repetições por tratamento), formando dois conjuntos de parcelas experimentais de acordo com o tipo de irrigação. A comunidade de inimigos naturais foi amostrada por observações diretas em 20 plantas de tomate por parcela e nas plantas de coentro sacudindo-se as plantas em cima de uma bandeja onde eram coletados os insetos. A abundância, riqueza e diversidade das espécies de inimigos naturais foram maiores nas parcelas cultivadas com coentro, independente do sistema de irrigação. Nas parcelas plantadas em monocultura foram encontradas mais espécies quando o tomateiro foi irrigado por aspersão. No entanto, a resposta de cada espécie de inimigo natural ou grupo de espécies foi distinta para o consórcio ou o tipo de irrigação. Portanto, em períodos de baixa precipitação, o consórcio tomate + coentro e a irrigação por aspersão podem favorecer a conservação de inimigos naturais no agroecossistema do tomateiro orgânico.


The adoption of cultural practices such as companion plants and the kind of irrigation system can benefit the community of natural enemies in the agroecosystem due to the increase of more favorable microhabitats available and as a source of alternative resources, mainly in periods of low precipitation. This study evaluated how the tomato + coriander intercrop and the kind of irrigation (drip and sprinkler) could benefit the community of natural enemies in the tomato agroecosystem. This work was carried out in the experimental field of Embrapa Hortaliças, Gama, DF, from September to November 2008. The tomatoes were planted in monoculture or with coriander (companion plant) and irrigated by drip and sprinkler irrigation (three replicates per treatment), forming two groups of experimental plots according to the kind of irrigation. The community of natural enemies was sampled by the direct observation of specimens on 20 tomatoes plants per plot and in the treatments. Coriander plants were shaken over a plastic tray for collection of insects. The abundance, richness and diversity of natural enemies were higher in tomato + coriander plots, regardless of the irrigation system. We observed more species of natural enemies in tomato monoculture plots when it was irrigated by sprinkler irrigation. However, the cultural practices adopted had a different effect on each species or group of species. Therefore, in periods of low precipitation, the tomato + coriander consortium associated with sprinkler irrigation can enhance the conservation of natural enemies in the organic tomato agroecosystem.


Assuntos
Controle Biológico de Vetores/métodos , Solanum lycopersicum , Pragas da Agricultura , Coriandrum , Alimentos Orgânicos/análise
8.
J Bone Miner Res ; 12(5): 726-33, 1997 May.
Artigo em Inglês | MEDLINE | ID: mdl-9144338

RESUMO

It has been recently claimed that polymorphism for the vitamin D receptor (VDR) influences several aspects of calcium and bone metabolism. To evaluate the physiologic plausibility of these claims, we compared the abundance of the VDR mRNA in peripheral blood mononuclear cells (PBMCs) between different VDR genotypes using a quantitative reverse transcribed polymerase chain reaction-based method. The method is based on the coamplification of VDR cDNA and an internal standard consisting of known concentrations of a human VDR CDNA mutated at a BglII restriction site; the interassay coefficient of variation is 11%. To validate the method, we made use of earlier receptor binding studies indicating that normal human monocytes and activated, but not resting, lymphocytes expressed the VDR. The concentration of the VDR mRNA was 10(-8) to 10(-7) g/g of total RNA in cell-sorted monocytes and in in vitro activated lymphocytes, but only 10(-12) g/g of total mRNA in resting lymphocytes, establishing that the VDR mRNA determined by our method in PBMCs is due to constitutive expression in monocytes. Following an initial genotype screening of 85 normal volunteers by polymerase chain reaction or restriction fragment length polymorphism analysis, 14 individuals with the Bb genotype, 12 with the bb genotype, and 12 with the BB genotype were selected. The concentration of the VDR mRNA, corrected for the number of monocytes, was similar among the three genotype groups, as were the other variables examined: serum calcitriol, serum osteocalcin, and vertebral and hip bone density. We conclude that VDR polymorphism does not affect the abundance of the VDR mRNA.


Assuntos
Variação Genética , Leucócitos Mononucleares/química , Reação em Cadeia da Polimerase/métodos , RNA Mensageiro/sangue , Receptores de Calcitriol/genética , Idoso , Idoso de 80 Anos ou mais , Alelos , Feminino , Citometria de Fluxo , Genótipo , Humanos , Ativação Linfocitária , Masculino , Pessoa de Meia-Idade , Fito-Hemaglutininas/farmacologia , Reprodutibilidade dos Testes , Transcrição Gênica
10.
J Exp Med ; 183(4): 1427-36, 1996 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-8666901

RESUMO

Mice rendered deficient in IL-1 beta by gene targeting in embryonic stem cells develop and grow normally in a protected laboratory environment. Endotoxin-stimulated peritoneal macrophages from IL-1beta-deficient mice showed normal synthesis and cellular release of IL-1alpha after treatment with 5 mM ATP demonstrating that IL-1beta is not necessary for expression and release of the IL-1alpha isoform. Mice deficient in IL-1beta showed unaltered sensitivity to endotoxic shock, with or without pretreatment with D-galactosamine. In contrast, IL-1beta-deficient mice showed defective contact hypersensitivity responses to topically applied trinitrochlorobenzene (TNCB). This defect could be overcome either by application of very high doses of sensitizing antigen, or by local intradermal injection of recombinant IL-1beta immediately before antigen application. These data demonstrate an essential role for IL-1beta in contact hypersensitivity and suggest that IL-1beta acts early during the sensitization phase of response. They suggest an important role for IL-1beta in initiation of the host of response at the epidermal barrier.


Assuntos
Dermatite de Contato/imunologia , Interleucina-1/deficiência , Cloreto de Picrila/imunologia , Animais , Sequência de Bases , Dermatite de Contato/etiologia , Dermatite de Contato/terapia , Epiderme/imunologia , Marcação de Genes , Interleucina-1/genética , Interleucina-1/uso terapêutico , Macrófagos Peritoneais/imunologia , Camundongos , Camundongos Mutantes , Dados de Sequência Molecular , Proteínas Recombinantes/uso terapêutico , Choque Séptico/imunologia , Choque Séptico/mortalidade
11.
Science ; 264(5159): 703-7, 1994 Apr 29.
Artigo em Inglês | MEDLINE | ID: mdl-8171322

RESUMO

Mice rendered deficient in lymphotoxin (LT) by gene targeting in embryonic stem cells have no morphologically detectable lymph nodes or Peyer's patches, although development of the thymus appears normal. Within the white pulp of the spleen, there is failure of normal segregation of B and T cells. Spleen and peripheral blood contain CD4+CD8- and CD4-CD8+ T cells in a normal ratio, and both T cells subsets have an apparently normal lytic function. Lymphocytes positive for immunoglobulin M are present in increased numbers in both the spleen and peripheral blood. These data suggest an essential role for LT in the normal development of peripheral lymphoid organs.


Assuntos
Linfonodos/crescimento & desenvolvimento , Tecido Linfoide/crescimento & desenvolvimento , Linfotoxina-alfa/fisiologia , Animais , Linfócitos B/imunologia , Blastocisto , Citotoxicidade Imunológica , Feminino , Contagem de Leucócitos , Linfonodos/citologia , Linfonodos/imunologia , Tecido Linfoide/citologia , Tecido Linfoide/imunologia , Linfotoxina-alfa/genética , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Nódulos Linfáticos Agregados/citologia , Nódulos Linfáticos Agregados/crescimento & desenvolvimento , Nódulos Linfáticos Agregados/imunologia , Receptores do Fator de Necrose Tumoral/fisiologia , Baço/citologia , Baço/imunologia , Subpopulações de Linfócitos T/imunologia , Linfócitos T/imunologia , Timo/citologia , Timo/imunologia , Fator de Necrose Tumoral alfa/genética , Fator de Necrose Tumoral alfa/fisiologia
12.
J Virol ; 64(2): 499-508, 1990 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-2104941

RESUMO

We generated recombinant baculoviruses that contained the human fos gene and that, upon infection of insect cells, synthesized fos protein. The quantity of fos protein produced was at least 10 to 20 times higher than that observed in any mammalian cells reported so far. The fos protein made in insect cells manifested most of the characteristics of mammalian fos protein, which include (i) 55-kilodalton size, (ii) nuclear localization, (iii) phosphoesterification at serine residues, (iv) identical 35S tryptic peptide maps, (v) ability to make heterodimers with the nuclear jun oncoprotein, and (vi) cooperation with the jun protein to bind to a 12-O-tetradecanoyl-phorbol-13-acetate-responsive element. A 100- to 150-fold purification of the fos protein from infected insect cells was achieved in a single step by immunoaffinity chromatography. Availability of authentic fos protein made by baculoviral vectors in insect cells should allow a more rigorous analysis of its biochemical and biological properties.


Assuntos
Vetores Genéticos , Vírus de Insetos/genética , Proteínas Proto-Oncogênicas/genética , Proto-Oncogenes , Aminoácidos/análise , Animais , Linhagem Celular , Núcleo Celular/enzimologia , Cromatografia de Afinidade , Eletroforese em Gel Bidimensional , Imunofluorescência , Células HeLa/efeitos dos fármacos , Células HeLa/enzimologia , Humanos , Insetos , Mapeamento de Peptídeos , Fosfatos , Fosforilação , Plasmídeos , Proteínas Tirosina Quinases/genética , Proteínas Proto-Oncogênicas/isolamento & purificação , Proteínas Proto-Oncogênicas c-fos , Proteínas Recombinantes/isolamento & purificação , Acetato de Tetradecanoilforbol/farmacologia , Transfecção , Tripsina
13.
Plasmid ; 20(2): 143-7, 1988 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-2853394

RESUMO

A spontaneous mutation in pUC18 has revealed the insertion of a chromosomal insertion sequence (IS)2 element into the promoter region of the lac operon. The IS2 insertion site, at the pentanucleotide sequence TCGAG, is unlike previously described junctional sequences.


Assuntos
Elementos de DNA Transponíveis , Escherichia coli/genética , Óperon Lac , Plasmídeos , Regiões Promotoras Genéticas , Sequência de Bases , Dados de Sequência Molecular , Hibridização de Ácido Nucleico , Mapeamento por Restrição , Transformação Bacteriana
14.
Mol Cell Biol ; 8(5): 2251-6, 1988 May.
Artigo em Inglês | MEDLINE | ID: mdl-3133556

RESUMO

We have generated monoclonal antibodies by using a synthetic peptide corresponding to amino acid positions 4 to 17 of the human fos protein. The antibodies detected both v- and c-fos proteins by immunoprecipitation, immunoblotting, and indirect immunofluorescence. The monoclonal antibodies not only identified the fos protein complex with the cellular 39-kilodalton protein, but also recognized the modified forms of the mouse, rat, and human fos proteins. In day-17 rat embryos, nuclear-staining fos protein could be identified in the cartilage by immunohistochemical staining.


Assuntos
Osteogênese , Proteínas Proto-Oncogênicas/análise , Proteínas dos Retroviridae/análise , Animais , Anticorpos Monoclonais/imunologia , Cartilagem/análise , Cartilagem/embriologia , Produtos do Gene gag , Humanos , Proteínas Proto-Oncogênicas/imunologia , Proteínas Proto-Oncogênicas c-fos , Ratos , Proteínas dos Retroviridae/imunologia
15.
Blood ; 71(2): 463-6, 1988 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-3122860

RESUMO

The plasmid pUC18 contains a lacZ alpha-complementation gene that codes for a small peptide that can complement the delta M15 mutation of the Escherichia coli lacZ (beta-galactosidase) gene, converting bacteria carrying that mutated gene from the lacZ- to the lacZ+ phenotype. This plasmid was used in experiments designed to study mutagenesis by human neutrophils. E coli carrying pUC18 were incubated with neutrophils under conditions in which little ingestion of the bacteria took place; the plasmid was then isolated and transformed into an E coli strain (BOZO) that carries the lacZ delta M15 mutation. Of these transformants, 11 of 205,000 were lacZ, suggesting that in these 11, alpha-complementation had been lost through a mutation. No lac- colonies were detected among several hundred thousand BOZO transformed with plasmid isolated from incubations in which phagocytosis could take place, nor from incubations from which neutrophils were omitted. Despite the lac- phenotype of these 11 transformants, plasmids reisolated from nine of them showed normal alpha-complementing ability when transformed into fresh BOZO. These findings indicated that in these nine, the mutations were located in the chromosomes of the transformed BOZO. It thus appears that on exposure to activated neutrophils, a plasmid may acquire a lesion (? mutation) that can somehow be transferred to the genome of a recipient microorganism, resulting in repair of the damaged plasmid accompanied by mutation of the recipient's chromosome. Restriction mapping of the DNA from four of these nine chromosomal mutants suggested that the mutations did not represent major insertions or deletions in the portion of the bacterial chromosome corresponding to the pUC18 lac operon insert, nor in the remainder of the lacZ delta M15 gene. These results confirm previous work showing that exposure to activated neutrophils can induce mutations in biological systems, and provides an experimental model in which the mechanism of neutrophil-mediated mutagenesis may be examined.


Assuntos
DNA Bacteriano/genética , Mutação , Neutrófilos/microbiologia , Plasmídeos , Atividade Bactericida do Sangue , Genes , Óperon Lac , beta-Galactosidase/genética
16.
Blood ; 69(5): 1394-400, 1987 May.
Artigo em Inglês | MEDLINE | ID: mdl-3032306

RESUMO

Escherichia coli minicells containing the plasmid pSC101 (approximately 10 kb) or pBR322 (approximately 4 kb) were opsonized and incubated with human neutrophils. The neutrophils responded to the minicells as they would to native E coli: they ingested the minicells, discharged their granule contents into the minicell-containing phagosomes, and expressed a respiratory burst. After one hour of incubation, the fate of the ingested plasmid DNA was examined. No DNA degradation was detected by trichloroacetic acid precipitation or agarose gel electrophoresis. Moreover, when pBR322 recovered from ingested minicells was transformed into E coli, no mutations in either of the antibiotic resistance genes carried by the plasmid were detected out of many thousand transformants screened. These findings confirm the surprisingly limited effect of neutrophils on ingested DNA.


Assuntos
DNA Bacteriano/metabolismo , Escherichia coli/metabolismo , Neutrófilos/metabolismo , Plasmídeos , Atividade Bactericida do Sangue , Ativação Enzimática , Escherichia coli/citologia , Escherichia coli/genética , Humanos , Microscopia Eletrônica , Mutação , Neutrófilos/enzimologia , Neutrófilos/ultraestrutura , Peroxidase/metabolismo , Fagossomos/fisiologia , Superóxidos/metabolismo
17.
Hypertension ; 9(3): 230-5, 1987 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-3818020

RESUMO

Intracellular free calcium, [Ca2+]i, was studied in platelets of essential hypertensive subjects and normotensive controls under basal conditions and after stimulation with epinephrine, norepinephrine, angiotensin II, ouabain, and thrombin, using the fluorescent calcium indicator quin 2. Basal [Ca2+]i was significantly higher in hypertensive subjects (n = 32) than in normotensive controls (n = 30; 167.4 +/- 5.0 vs 143.2 +/- 3.1 nmol/L; p less than 0.001). Epinephrine, norepinephrine, angiotensin II, and ouabain had no effect on platelet calcium, whereas thrombin induced a dose-dependent increase in [Ca2+]i in both the presence and absence of extracellular calcium. This [Ca2+]i increase in the presence of extracellular calcium, which depends mainly on calcium influx, was significantly higher (p less than 0.05) in platelets of hypertensive subjects at all thrombin concentrations (ranging from 0.025-0.1 U/ml), while the [Ca2+]i increase in the absence of extracellular calcium, which depends only on release from intracellular stores, was similar in hypertensive subjects and controls. These results suggest that, in essential hypertension, there is not only increased platelet resting [Ca2+]i but also an increase in agonist-mediated calcium influx, which appears to indicate a cell membrane abnormality in the platelets of subjects with essential hypertension.


Assuntos
Plaquetas/metabolismo , Cálcio/sangue , Hipertensão/sangue , Trombina/farmacologia , Adulto , Angiotensina II/farmacologia , Relação Dose-Resposta a Droga , Epinefrina/farmacologia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Norepinefrina/farmacologia , Ouabaína/farmacologia
18.
Thromb Haemost ; 56(3): 308-10, 1986 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-2436332

RESUMO

We studied the inhibitory effects of the calcium channel blocker verapamil both on platelet aggregation and intracellular calcium [Ca2+]i in platelets loaded with a fluorescent indicator (quin 2). The inhibitory effects of verapamil on the platelet aggregation response to both thrombin and ionomycin were seen to be clearly dissociated from the verapamil-induced inhibition of the [Ca2+]i increase produced by these agonists. Verapamil-induced inhibition of platelet aggregation was also obtained when using the "calcium-independent" agonist phorbol-myristate acetate (PMA). It may be deduced that a calcium-independent mechanism plays a role in verapamil-induced inhibition of platelet aggregation. We postulate that this mechanism may operate via a protein-kinase C pathway.


Assuntos
Cálcio/fisiologia , Agregação Plaquetária/efeitos dos fármacos , Verapamil/farmacologia , Éteres/farmacologia , Humanos , Canais Iônicos/efeitos dos fármacos , Ionomicina , Acetato de Tetradecanoilforbol/farmacologia , Trombina/farmacologia
19.
Biochim Biophys Acta ; 886(3): 441-7, 1986 May 29.
Artigo em Inglês | MEDLINE | ID: mdl-3011119

RESUMO

The effect of increased intracellular levels of cyclic AMP on phosphoinositide metabolism was studied in human neutrophils stimulated with fMet-Leu-Phe. Intracellular cyclic AMP was raised by preincubation either with dibutyryl cyclic AMP and theophylline or with prostaglandin E1. Concentrations of dibutyryl cyclic AMP and theophylline fully inhibitory for the metabolic responses inhibited phosphoinositide breakdown and phosphatidic acid formation to a large extent. The accumulation of the water-soluble inositol phosphates was also measured. In agreement with the data obtained on the phospholipids, inositol phosphate generation was found to be severely, though not completely, reduced. Treatment with dibutyryl cyclic AMP and theophylline also inhibited resynthesis of membrane inositol lipids. Treatment with prostaglandin E1 had a similar, though less, marked effect on inositol lipid turnover, which was parallel with a smaller inhibition of metabolic responses. We therefore suggest that the elevation of intracellular cyclic AMP mainly affects neutrophil responses by inhibiting the phosphoinositide cycle.


Assuntos
AMP Cíclico/farmacologia , Neutrófilos/metabolismo , Fosfatidilinositóis/metabolismo , Alprostadil/farmacologia , Bucladesina/farmacologia , Diglicerídeos/biossíntese , Humanos , Líquido Intracelular/metabolismo , Lipídeos de Membrana/metabolismo , N-Formilmetionina Leucil-Fenilalanina/farmacologia , Neutrófilos/efeitos dos fármacos , Teofilina/farmacologia , Fosfolipases Tipo C/metabolismo
20.
Biochim Biophys Acta ; 845(2): 223-36, 1985 May 30.
Artigo em Inglês | MEDLINE | ID: mdl-2986719

RESUMO

Verapamil inhibits in human neutrophils the respiratory burst, the secretion and the change of transmembrane potential induced by formylmethionylleucylphenylalanine, a Ca2+-dependent stimulus, and by phorbol myristate acetate, a Ca2+-independent stimulus. Besides the blocking of Ca2+ channels, many mechanisms are responsible for the inhibition of neutrophil responses. In fact, verapamil (i) increases the intracellular cAMP concentration, potentiates the cAMP response induced by the chemotactic peptide and induces the appearance of a cAMP response also when the stimulant is phorbol myristate acetate; (ii) causes a decrease of Ca2+ association to cell membranes, so depleting the pools of exchangeable Ca2+ and depressing the 'Ca2+ response' in terms of rise in [Ca2+]i monitored with Quin 2 and of rapid mobilization from cell membranes monitored by chlorotetracycline fluorescence change; (iii) inhibits the Ca2+-activated phospholipid-dependent protein kinase C. The data, discussed in relation to the biochemical mechanisms of the stimulus-response coupling, are compatible with the hypothesis of an involvement of the activation of protein kinase C as key step in the sequence of transduction events for the induction of many neutrophil functions.


Assuntos
N-Formilmetionina Leucil-Fenilalanina/farmacologia , Neutrófilos/fisiologia , Forbóis/farmacologia , Proteínas Quinases/metabolismo , Acetato de Tetradecanoilforbol/farmacologia , Verapamil/farmacologia , Cálcio/metabolismo , Cálcio/farmacologia , Membrana Celular/metabolismo , AMP Cíclico/metabolismo , Grânulos Citoplasmáticos/fisiologia , Citosol/metabolismo , Ativação Enzimática/efeitos dos fármacos , Humanos , Potenciais da Membrana/efeitos dos fármacos , Neutrófilos/efeitos dos fármacos , Consumo de Oxigênio/efeitos dos fármacos , Fosfatidilserinas/farmacologia , Proteína Quinase C
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