RESUMO
The Australian and New Zealand Guidelines for Fresh and Marine Water Quality are a key document in the Australian National Water Quality Management Strategy. These guidelines released in 2000 are currently being reviewed and updated. The revision is being co-ordinated by the Australian Department of Sustainability, Environment, Water, Population and Communities, while technical matters are dealt with by a series of Working Groups. The revision will be evolutionary in nature reflecting the latest scientific developments and a range of stakeholder desires. Key changes will be: increasing the types and sources of data that can be used; working collaboratively with industry to permit the use of commercial-in-confidence data; increasing the minimum data requirements; including a measure of the uncertainty of the trigger value; improving the software used to calculate trigger values; increasing the rigour of site-specific trigger values; improving the method for assessing the reliability of the trigger values; and providing guidance of measures of toxicity and toxicological endpoints that may, in the near future, be appropriate for trigger value derivation. These changes will markedly improve the number and quality of the trigger values that can be derived and will increase end-users' ability to understand and implement the guidelines in a scientifically rigorous manner.
Assuntos
Política Ambiental , Poluentes Químicos da Água/normas , Austrália , Monitoramento Ambiental , Água Doce/química , Guias como Assunto , Nova Zelândia , Água do Mar/química , Poluentes Químicos da Água/análise , Poluentes Químicos da Água/toxicidade , Qualidade da ÁguaRESUMO
Pesticides predominantly occur in aquatic ecosystems as mixtures of varying complexity, yet relatively few studies have examined the toxicity of pesticide mixtures. Atrazine, chlorothalonil and permethrin are widely used pesticides that have different modes of action. This study examined the chronic toxicities (7-d reproductive impairment) of these pesticides in binary and ternary mixtures to the freshwater cladoceran Ceriodaphnia cf. dubia. The toxicity of the mixtures was compared to that predicted by the independent action (IA) model for mixtures, as this is the most appropriate model for chemicals with different modes of action. Following this they were compared to the toxicity predicted by the concentration addition (CA) model for mixtures. According to the IA model, the toxicity of the chlorothalonil plus atrazine mixture conformed to antagonism, while that of chlorothalonil and permethrin conformed to synergism. The toxicity of the atrazine and permethrin mixture as well as the ternary mixture conformed to IA implying there was either no interaction between the components of these mixtures and/or in the case of the ternary mixture the interactions cancelled each other out to result in IA. The synergistic and antagonistic mixtures deviated from IA by factors greater than 3 and less than 2.5, respectively. When the toxicity of the mixtures was compared to the predictions of the CA model, the binary mixture of chlorothalonil plus atrazine, permethrin plus atrazine and the ternary mixture all conformed to antagonism, while the binary mixture of chlorothalonil plus permethrin conformed to CA. Using the CA model provided estimates of mixture toxicity that did not markedly underestimate the measured toxicity, unlike the IA model, and therefore the CA model is the most suitable to use in ecological risk assessments of these pesticides.
Assuntos
Cladocera/efeitos dos fármacos , Praguicidas/toxicidade , Poluentes Químicos da Água/toxicidade , Animais , Atrazina/toxicidade , Sinergismo Farmacológico , Nitrilas/toxicidade , Permetrina/toxicidade , Testes de ToxicidadeRESUMO
The toxicity of carbaryl, chlorpyrifos, dimethoate and profenofos to the freshwater shrimp, Paratya australiensis was assessed by measuring acetylcholinesterase (AChE) inhibition after 96h exposures. Shrimp exposed to these pesticides exhibited significant AChE inhibition, with mortality in shrimp corresponding to 70-90% AChE inhibition. The sensitivity of P. australiensis to the four pesticides based on AChE inhibition can be given as chlorpyrifos > profenofos > carbaryl > dimethoate. Recovery of AChE activity was followed in shrimp after 96 h exposures to carbaryl, chlorpyrifos and dimethoate. Recovery after exposure to the carbamate pesticide carbaryl was more rapid than for the two organophosphorus pesticides, chlorpyrifos and dimethoate. The slow recovery of depressed AChE activity may mean that affected organisms in the natural system are unable to sustain physical activities such as searching for food or eluding predators. To investigate the ecological significance of AChE inhibition, chemotaxis behaviour was assessed in shrimp exposed to profenofos for 24h. Abnormal chemotaxis behaviour in the exposed shrimp was observed at concentrations representing 30-50% AChE inhibition. A clear relationship existed between the depression of AChE activity and observed chemotaxis responses, such as approaching and grasping the chemoattractant source. These results suggest that in vivo toxicity tests based on this specific biomarker are sensitive and present advantages over conventional acute tests based on mortality. Behavioural studies of test organisms conducted in conjunction with measurement of AChE inhibition will provide data to clarify the toxic effects caused by sublethal chemical concentrations of anti-cholinesterase compounds.
Assuntos
Acetilcolinesterase/metabolismo , Quimiotaxia/efeitos dos fármacos , Inibidores da Colinesterase/toxicidade , Decápodes/efeitos dos fármacos , Decápodes/enzimologia , Inseticidas/toxicidade , Poluentes Químicos da Água/toxicidade , Análise de Variância , Animais , Carbaril , Clorpirifos , Inibidores da Colinesterase/análise , Cromatografia Líquida de Alta Pressão , Dimetoato , Cromatografia Gasosa-Espectrometria de Massas , Inseticidas/análise , Organotiofosfatos , Sensibilidade e Especificidade , Austrália do Sul , Fatores de Tempo , Testes de Toxicidade , Poluentes Químicos da Água/análiseRESUMO
The reference sequence for each human chromosome provides the framework for understanding genome function, variation and evolution. Here we report the finished sequence and biological annotation of human chromosome 1. Chromosome 1 is gene-dense, with 3,141 genes and 991 pseudogenes, and many coding sequences overlap. Rearrangements and mutations of chromosome 1 are prevalent in cancer and many other diseases. Patterns of sequence variation reveal signals of recent selection in specific genes that may contribute to human fitness, and also in regions where no function is evident. Fine-scale recombination occurs in hotspots of varying intensity along the sequence, and is enriched near genes. These and other studies of human biology and disease encoded within chromosome 1 are made possible with the highly accurate annotated sequence, as part of the completed set of chromosome sequences that comprise the reference human genome.
Assuntos
Cromossomos Humanos Par 1/genética , Sequência de Bases , Período de Replicação do DNA , Doença , Duplicação Gênica , Genes/genética , Variação Genética/genética , Genômica , Humanos , Dados de Sequência Molecular , Fases de Leitura Aberta/genética , Pseudogenes/genética , Recombinação Genética/genética , Seleção Genética , Análise de Sequência de DNARESUMO
Chromosome 9 is highly structurally polymorphic. It contains the largest autosomal block of heterochromatin, which is heteromorphic in 6-8% of humans, whereas pericentric inversions occur in more than 1% of the population. The finished euchromatic sequence of chromosome 9 comprises 109,044,351 base pairs and represents >99.6% of the region. Analysis of the sequence reveals many intra- and interchromosomal duplications, including segmental duplications adjacent to both the centromere and the large heterochromatic block. We have annotated 1,149 genes, including genes implicated in male-to-female sex reversal, cancer and neurodegenerative disease, and 426 pseudogenes. The chromosome contains the largest interferon gene cluster in the human genome. There is also a region of exceptionally high gene and G + C content including genes paralogous to those in the major histocompatibility complex. We have also detected recently duplicated genes that exhibit different rates of sequence divergence, presumably reflecting natural selection.
Assuntos
Cromossomos Humanos Par 9/genética , Genes , Mapeamento Físico do Cromossomo , Composição de Bases , Eucromatina/genética , Evolução Molecular , Feminino , Duplicação Gênica , Genes Duplicados/genética , Variação Genética/genética , Genética Médica , Genômica , Heterocromatina/genética , Humanos , Masculino , Neoplasias/genética , Doenças Neurodegenerativas/genética , Pseudogenes/genética , Análise de Sequência de DNA , Processos de Determinação SexualRESUMO
The finished sequence of human chromosome 10 comprises a total of 131,666,441 base pairs. It represents 99.4% of the euchromatic DNA and includes one megabase of heterochromatic sequence within the pericentromeric region of the short and long arm of the chromosome. Sequence annotation revealed 1,357 genes, of which 816 are protein coding, and 430 are pseudogenes. We observed widespread occurrence of overlapping coding genes (either strand) and identified 67 antisense transcripts. Our analysis suggests that both inter- and intrachromosomal segmental duplications have impacted on the gene count on chromosome 10. Multispecies comparative analysis indicated that we can readily annotate the protein-coding genes with current resources. We estimate that over 95% of all coding exons were identified in this study. Assessment of single base changes between the human chromosome 10 and chimpanzee sequence revealed nonsense mutations in only 21 coding genes with respect to the human sequence.
Assuntos
Cromossomos Humanos Par 10/genética , Genes , Mapeamento Físico do Cromossomo , Animais , Composição de Bases , Mapeamento de Sequências Contíguas , Ilhas de CpG/genética , Evolução Molecular , Éxons/genética , Duplicação Gênica , Variação Genética/genética , Genética Médica , Genômica , Humanos , Pan troglodytes/genética , Proteínas/genética , Pseudogenes/genética , Análise de Sequência de DNARESUMO
Chromosome 13 is the largest acrocentric human chromosome. It carries genes involved in cancer including the breast cancer type 2 (BRCA2) and retinoblastoma (RB1) genes, is frequently rearranged in B-cell chronic lymphocytic leukaemia, and contains the DAOA locus associated with bipolar disorder and schizophrenia. We describe completion and analysis of 95.5 megabases (Mb) of sequence from chromosome 13, which contains 633 genes and 296 pseudogenes. We estimate that more than 95.4% of the protein-coding genes of this chromosome have been identified, on the basis of comparison with other vertebrate genome sequences. Additionally, 105 putative non-coding RNA genes were found. Chromosome 13 has one of the lowest gene densities (6.5 genes per Mb) among human chromosomes, and contains a central region of 38 Mb where the gene density drops to only 3.1 genes per Mb.
Assuntos
Cromossomos Humanos Par 13/genética , Genes/genética , Mapeamento Físico do Cromossomo , Mapeamento Cromossômico , Genética Médica , Humanos , Pseudogenes/genética , RNA não Traduzido/genética , Análise de Sequência de DNARESUMO
Chromosome 6 is a metacentric chromosome that constitutes about 6% of the human genome. The finished sequence comprises 166,880,988 base pairs, representing the largest chromosome sequenced so far. The entire sequence has been subjected to high-quality manual annotation, resulting in the evidence-supported identification of 1,557 genes and 633 pseudogenes. Here we report that at least 96% of the protein-coding genes have been identified, as assessed by multi-species comparative sequence analysis, and provide evidence for the presence of further, otherwise unsupported exons/genes. Among these are genes directly implicated in cancer, schizophrenia, autoimmunity and many other diseases. Chromosome 6 harbours the largest transfer RNA gene cluster in the genome; we show that this cluster co-localizes with a region of high transcriptional activity. Within the essential immune loci of the major histocompatibility complex, we find HLA-B to be the most polymorphic gene on chromosome 6 and in the human genome.
Assuntos
Cromossomos Humanos Par 6/genética , Genes/genética , Mapeamento Físico do Cromossomo , Animais , Éxons/genética , Doenças Genéticas Inatas/genética , Antígenos HLA-B/genética , Humanos , Pseudogenes/genética , RNA de Transferência/genética , Análise de Sequência de DNARESUMO
We report the case of an 8-year-old child who presented with severe hyperinsulinaemic hypoglycaemia due to a pancreatic islet cell adenoma. In vivo, there was no beneficial response to the hyperglycaemia-inducing agent diazoxide and as a consequence the child underwent a subtotal pancreatectomy. In vitro studies of adenomatous beta-cells revealed no operational defects in ATP-sensitive potassium channel activity and appropriate responses to diazoxide. In comparison with patients with focal adenomatous hyperplasia, genetic analysis of the isolated adenoma showed no loss of heterozygosity for chromosome 11p15 and expression of the cyclin-dependent kinase inhibitor p57(kip2). This case illustrates that the excess insulin secretion from an infantile adenoma has an aetiology different from that observed in hyperinsulinism in infancy.
Assuntos
Adenoma de Células das Ilhotas Pancreáticas/metabolismo , Trifosfato de Adenosina/metabolismo , Insulina/metabolismo , Ilhotas Pancreáticas/metabolismo , Neoplasias Pancreáticas/metabolismo , Canais de Potássio/metabolismo , Adenoma de Células das Ilhotas Pancreáticas/complicações , Adenoma de Células das Ilhotas Pancreáticas/genética , Anti-Hipertensivos/uso terapêutico , Criança , Cromossomos Humanos Par 11/genética , Diazóxido/uso terapêutico , Feminino , Humanos , Hiperinsulinismo/etiologia , Hipoglicemia/etiologia , Secreção de Insulina , Perda de Heterozigosidade , Proteínas Associadas aos Microtúbulos/metabolismo , Proteínas Motores Moleculares , Pancreatectomia , Neoplasias Pancreáticas/complicações , Neoplasias Pancreáticas/genética , Proteínas de Saccharomyces cerevisiae/metabolismoRESUMO
PROBLEM: Female mice injected with estradiol-17beta (E2) and testosterone during the immune adaptive period are infertile as adults. Study 1 examined the effect of the day of injection of E2 and testosterone on the incidence of infertility in two strains of mice. Study 2 examined the effect of hydrocortisone on E2-induced infertility. METHOD OF STUDY: Study 1: Neonatal (C57BL/6J x A/J)F1 B6A and (C3H/HeJ x 129J)F1 C31 female mice were injected from 0 to 3 and from 3 to 6 days of age with either 20 microg E2 or 20 microg testosterone. Animals were tested for fertility by mating with fertile males. Study 2: Neonatal B6A females were injected with 20 microg E2 with/without 1000 microg hydrocortisone on days 1, 3, 5, 7, and 10. At adulthood, ovaries were examined for the presence of corpora lutea (CLs). RESULTS: Study 1: The incidence of E2-induced infertility in adult B6A and C31 females decreased over three consecutive matings. In contrast, the incidence of testosterone-induced infertility in adult B6A and C31 females increased. E2 caused the highest incidence of infertility in C31 females when injected prior to 3 days of age. In B6A mice, E2 caused the highest incidence of infertility when injected after 3 days of age. Study 2: When hydrocortisone was injected with E2, 90% of the B6A females had ovaries with CLs at 100 days of age. Without hydrocortisone, only 16% of the B6A females injected with E2 had ovaries with CLs. CONCLUSION: Study 1: The incidence of infertility caused by injections of E2 is dependent on the strain of mice and the day(s) injected. The incidence of infertility caused by injections of testosterone is independent of the strain of mice. Study 2: Hydrocortisone prevents E2-induced infertility. It is proposed that injections of E2 during the immune adaptive period alter T-cell maturation, which contributes to E2-induced infertility.
Assuntos
Adaptação Fisiológica/imunologia , Anti-Inflamatórios/efeitos adversos , Estradiol/efeitos adversos , Fertilidade/efeitos dos fármacos , Hidrocortisona/efeitos adversos , Testosterona/efeitos adversos , Animais , Anti-Inflamatórios/administração & dosagem , Estradiol/administração & dosagem , Feminino , Fertilidade/imunologia , Hidrocortisona/administração & dosagem , Masculino , Camundongos , Camundongos Endogâmicos C3H , Camundongos Endogâmicos C57BL , Óleo de Gergelim/administração & dosagem , Óleo de Gergelim/farmacologia , Testosterona/administração & dosagemRESUMO
The organophosphorus (OP) pesticide profenofos (O-4-bromo-2-chlorophenyl O-ethyl S-propyl phosphorothioate) is used heavily in cotton-growing areas of eastern Australia toward the end of the growing season. European carp (Cyprinus carpio), bony bream (Nematalosa erebi), and mosquitofish (Gambusia holbrooki) were collected from the cotton-growing areas around Wee Waa, New South Wales, to determine the relationship between profenofos residues and acetyl-cholinesterase (AChE) activity in wild fish. Profenofos concentrations in water, sediment, and fish tissue reflected its general level of use; levels in March 1994 were significantly higher than in 1993 and generally decreased in May, 6 wk after cessation of spraying. Residues in carp and bony bream generally correlated with concentrations in water and sediment, although residues in fish tend to persist longer at some sites. Acetylcholinesterase inhibition was a useful indicator of profenofos exposure within a season, particularly if linked with residue measurements. Bony bream and gravid female mosquitofish recovered AChE levels more slowly than carp or nongravid mosquitofish. Recovery in creeks was generally more rapid than in lagoons.
Assuntos
Peixes , Inseticidas/farmacocinética , Organotiofosfatos/farmacocinética , Resíduos de Praguicidas/farmacocinética , Poluentes Químicos da Água/farmacocinética , Acetilcolinesterase/análise , Agricultura , Animais , Monitoramento Ambiental , Feminino , Gossypium , Inseticidas/análise , Masculino , Organotiofosfatos/análise , Resíduos de Praguicidas/análise , Reprodução , Distribuição Tecidual , Poluentes Químicos da Água/análiseRESUMO
Hyperinsulinism of infancy (HI) is a congenital defect in the regulated release of insulin from pancreatic beta-cells. Here we describe stimulus-secretion coupling mechanisms in beta-cells and intact islets of Langerhans isolated from three patients with a novel SUR1 gene defect. 2154+3 A to G SUR1 (GenBank accession number L78207) is the first report of familial HI among nonconsanguineous Caucasians identified in the U.K. Using patch-clamp methodologies, we have shown that this mutation is associated with both a decrease in the number of operational ATP-sensitive K+ channels (KATP channels) in beta-cells and impaired ADP-dependent regulation. There were no apparent defects in the regulation of Ca2+- and voltage-gated K+ channels or delayed rectifier K+ channels. Intact HI beta-cells were spontaneously electrically active and generating Ca2+ action currents that were largely insensitive to diazoxide and somatostatin. As a consequence, when intact HI islets were challenged with glucose and tolbutamide, there was no rise in intracellular free calcium ion concentration ([Ca2+]i) over basal values. Capacitance measurements used to monitor exocytosis in control and HI beta-cells revealed that there were no defects in Ca2+-dependent exocytotic events. Finally, insulin release studies documented that whereas tolbutamide failed to cause insulin secretion as a consequence of impaired [Ca2+]i signaling, glucose readily promoted insulin release. Glucose was also found to augment the actions of protein kinase C- and protein kinase A-dependent agonists in the absence of extracellular Ca2+. These findings document the relationship between SUR1 gene defects and insulin secretion in vivo and in vitro and describe for the first time KATP channel-independent pathways of regulated insulin secretion in diseased human beta-cells.
Assuntos
Transportadores de Cassetes de Ligação de ATP , Trifosfato de Adenosina/fisiologia , Hiperinsulinismo/congênito , Hiperinsulinismo/metabolismo , Insulina/metabolismo , Ilhotas Pancreáticas/metabolismo , Canais de Potássio Corretores do Fluxo de Internalização , Canais de Potássio/fisiologia , Difosfato de Adenosina/fisiologia , Cálcio/fisiologia , Sinalização do Cálcio , Citosol/fisiologia , Exocitose/fisiologia , Genótipo , Humanos , Hiperinsulinismo/genética , Hiperinsulinismo/fisiopatologia , Técnicas In Vitro , Recém-Nascido , Secreção de Insulina , Ilhotas Pancreáticas/fisiopatologia , Dados de Sequência Molecular , Mutação/fisiologia , Técnicas de Patch-Clamp , Canais de Potássio/genética , Canais de Potássio/metabolismo , Receptores de Droga/genética , Receptores de Droga/metabolismo , Receptores de SulfonilureiasRESUMO
The finished sequence of human chromosome 20 comprises 59,187,298 base pairs (bp) and represents 99.4% of the euchromatic DNA. A single contig of 26 megabases (Mb) spans the entire short arm, and five contigs separated by gaps totalling 320 kb span the long arm of this metacentric chromosome. An additional 234,339 bp of sequence has been determined within the pericentromeric region of the long arm. We annotated 727 genes and 168 pseudogenes in the sequence. About 64% of these genes have a 5' and a 3' untranslated region and a complete open reading frame. Comparative analysis of the sequence of chromosome 20 to whole-genome shotgun-sequence data of two other vertebrates, the mouse Mus musculus and the puffer fish Tetraodon nigroviridis, provides an independent measure of the efficiency of gene annotation, and indicates that this analysis may account for more than 95% of all coding exons and almost all genes.
Assuntos
Cromossomos Humanos Par 20 , Animais , Sequência de Bases , Biologia Computacional , Mapeamento de Sequências Contíguas , DNA , Doenças Genéticas Inatas/genética , Variação Genética , Humanos , Camundongos , Mapeamento Físico do Cromossomo , Proteoma , Análise de Sequência de DNARESUMO
PROBLEM: Neonatal estradiol injections in mice lead to follicular cystic ovaries that are similar to ovaries in patients with polycystic ovarian syndrome (PCOS). The present study examined ovarian cytokine production following neonatal estradiol injection. METHOD OF STUDY: Female (C3H,HeJ x 129/HeJ)F1 mice were injected daily with 20 microg 17beta-estradiol from 0-3 days postpartum. At intervals, animals were sacrificed to determine ovarian architecture, circulating levels of estradiol, ovarian and peritoneal macrophage cytokine production, and ovarian P450 aromatase enzyme mRNA levels. RESULTS: Similar to PCOS, our results show that neonatally estradiol-injected mice have lower levels of circulating estrogen that are correlated with decreased mRNA levels of P450 aromatase enzyme. Our data also show that follicular cystic ovaries have increased tumor necrosis factor (TNF)-alpha and interleukin (IL)-6 production. This increase in TNF-alpha and IL-6 production is also observed in peritoneal macrophages of estradiol-injected mice. CONCLUSION: The present study showed that neonatal estrogen injection in mice has an overall systemic effect on cytokine production. We speculate that increased cytokine production may alter certain important steps in follicular maturation, ultimately contributing to ovarian dysfunction.
Assuntos
Estradiol/farmacologia , Interleucina-6/biossíntese , Ovário/metabolismo , Síndrome do Ovário Policístico/metabolismo , Fator de Necrose Tumoral alfa/biossíntese , Animais , Animais Recém-Nascidos , Aromatase/genética , Estradiol/sangue , Feminino , Interleucina-6/genética , Macrófagos Peritoneais/metabolismo , Camundongos , Camundongos Endogâmicos C3H , RNA Mensageiro/análise , Fator de Necrose Tumoral alfa/genéticaRESUMO
Colonies of house mice reach maximum population density in 120-180 days, irrespective of cage size and initial number of colonizing animals. Reproduction ceases because the females become aggressive and unreceptive to mating. The aggressive behavior is correlated with elevated levels of testosterone (T) and corticosterone (B) (Chapman et al., Phys Behav 64:529-533, 1998). In two of seven strains of mice, females developed ovarian lesions. The occurrence of the lesion in one strain was correlated with the age of the animal and duration of the study. In the second strain, cage size was the determining factor. Lesioned ovaries weighed significantly more than nonlesioned ovaries. The lesion consisted of accumulations of luteal membrane and organelle fragments, and other cellular debris, suggestive of incomplete and prolonged luteolysis. Electron microscopic (EM) analyses revealed the presence of deposits of permanganate-resistant congophilic amyloid fibrils in the intima and smooth muscle cells of luteal thecal arteries. Population females had thymus glands and uteri that weighed significantly less than the same organs from females housed in the breeding colony, whereas the adrenal glands from the population females weighed significantly more. It is proposed that the female aggression is due to high levels of T. It is also proposed that the high levels of B suppress the immune cells involved in normal luteolysis and contribute to the incomplete and prolonged luteolysis.
Assuntos
Agressão , Comportamento Animal , Doenças Ovarianas/epidemiologia , Amiloide/análise , Amiloidose/complicações , Amiloidose/epidemiologia , Amiloidose/patologia , Animais , Feminino , Histocitoquímica , Masculino , Camundongos , Microscopia Eletrônica , Tamanho do Órgão , Doenças Ovarianas/complicações , Doenças Ovarianas/patologia , Ovário/química , Ovário/patologia , Densidade Demográfica , Pielonefrite/complicações , Pielonefrite/epidemiologia , Pielonefrite/patologia , Reprodução , Útero/patologiaRESUMO
A 39-year-old male developed painful ulceration of the glans penis following simultaneous pancreas and kidney transplantation for end-stage renal failure complicating insulin-dependent diabetes mellitus. Infection was excluded. Diversion of the pancreatic secretions away from the urinary bladder into the bowel resulted in healing.
Assuntos
Transplante de Rim/efeitos adversos , Transplante de Pâncreas/efeitos adversos , Doenças do Pênis/etiologia , Doenças Uretrais/etiologia , Adulto , Anastomose Cirúrgica/efeitos adversos , Diabetes Mellitus Tipo 1/cirurgia , Duodeno/cirurgia , Humanos , Falência Renal Crônica/cirurgia , Masculino , Pâncreas/metabolismo , Úlcera/etiologia , Bexiga Urinária/cirurgiaRESUMO
The properties of ATP-sensitive K+ (K(ATP)) channels were explored in the electrofusion-derived, glucose-responsive, insulin-secreting cell line BRIN-BD11 using patch-clamp techniques. In intact cells, K(ATP) channels were inhibited by glucose, the sulfonylurea tolbutamide, and the imidazoline compounds efaroxan and phentolamine. Each of these agents initiated insulin secretion and potentiated the actions of glucose. K(ATP) channels were blocked by ATP in a concentration-dependent manner and activated by ADP in the presence of ATP. In both intact cells and excised inside-out patches, the K(ATP) channel agonists diazoxide and pinacidil activated channels, and both compounds inhibited insulin secretion evoked by glucose, tolbutamide, and imidazolines. The mechanisms of action of imidazolines were examined in more detail. Pre-exposure of BRIN-BD11 cells to either efaroxan or phentolamine selectively inhibited imidazoline-induced insulin secretion but not the secretory responses of cells to glucose, tolbutamide, or a depolarizing concentration of KCl. These conditions did not result in the loss of depolarization-dependent rises in intracellular Ca2+ ([Ca2+]i), K(ATP) channel operation, or the actions of either ATP or efaroxan on K(ATP) channels. Desensitization of the imidazoline receptor following exposure to high concentrations of efaroxan, however, was found to result in an increase in SUR1 protein expression and, as a consequence, an upregulation of K(ATP) channel density. Our data provide 1) the first characterization of K(ATP) channels in BRIN-BD11 cells, a novel insulin-secreting cell line produced by electrofusion techniques, and 2) a further analysis of the role of imidazolines in the control of insulin release.
Assuntos
Trifosfato de Adenosina/farmacologia , Antagonistas Adrenérgicos alfa/farmacologia , Benzofuranos/farmacologia , Imidazóis/farmacologia , Insulina/metabolismo , Ilhotas Pancreáticas/fisiologia , Canais de Potássio/fisiologia , Difosfato de Adenosina/farmacologia , Animais , Fusão Celular , Linhagem Celular , Diazóxido/farmacologia , Glucose/farmacologia , Secreção de Insulina , Insulinoma , Ilhotas Pancreáticas/efeitos dos fármacos , Ilhotas Pancreáticas/metabolismo , Potenciais da Membrana/efeitos dos fármacos , Neoplasias Pancreáticas , Fentolamina/farmacologia , Pinacidil/farmacologia , Tolbutamida/farmacologia , Células Tumorais CultivadasRESUMO
The molecular defects of three different slow-migrating genetic variants of human serum albumin, albumins Kamloops (formerly RIH), Stirling and Amsterdam, previously characterized only by electrophoretic and dye-binding studies, are now reported. Two of them are proalbumin variants: sequential analysis of the purified whole proteins has established the mutation responsible for albumin Kamloops as -1Arg-->Gln, and for albumin Stirling as -2Arg-->His. A Glu-->Lys substitution in position 570 of the mature albumin molecule was determined in albumin Amsterdam by sequential analysis of two abnormal tryptic fragments. The three alloalbumins are caused by single-base changes all of which seem to represent hot-spots in the albumin gene. The possible functional consequences of the presence of a circulating alloalbumin are discussed.
Assuntos
Variação Genética , Albumina Sérica/genética , Sequência de Aminoácidos , Substituição de Aminoácidos , Heterozigoto , Humanos , Mutação , Albumina Sérica/química , Albumina Sérica/classificação , Albumina Sérica/isolamento & purificação , Albumina Sérica HumanaRESUMO
Persistent hyperinsulinemic hypoglycemia of infancy (PHHI) is a neonatal disease characterized by dysregulation of insulin secretion accompanied by profound hypoglycemia. We have discovered that islet cells, isolated from the pancreas of a PHHI patient, proliferate in culture while maintaining a beta cell-like phenotype. The PHHI-derived cell line (NES2Y) exhibits insulin secretory characteristics typical of islet cells derived from these patients, i.e. they have no K(ATP) channel activity and as a consequence secrete insulin at constitutively high levels in the absence of glucose. In addition, they exhibit impaired expression of the homeodomain transcription factor PDX1, which is a key component of the signaling pathway linking nutrient metabolism to the regulation of insulin gene expression. To repair these defects NES2Y cells were triple-transfected with cDNAs encoding the two components of the K(ATP) channel (SUR1 and Kir6.2) and PDX1. One selected clonal cell line (NISK9) had normal K(ATP) channel activity, and as a result of changes in intracellular Ca(2+) homeostasis ([Ca(2+)](i)) secreted insulin within the physiological range of glucose concentrations. This approach to engineering PHHI-derived islet cells may be of use in gene therapy for PHHI and in cell engineering techniques for administering insulin for the treatment of diabetes mellitus.
Assuntos
Transportadores de Cassetes de Ligação de ATP , Glucose/farmacologia , Proteínas de Homeodomínio , Hiperinsulinismo/genética , Hipoglicemia/genética , Insulina/metabolismo , Ilhotas Pancreáticas/citologia , Canais de Potássio Corretores do Fluxo de Internalização , Difosfato de Adenosina/farmacologia , Trifosfato de Adenosina/farmacologia , Animais , Cálcio/metabolismo , Linhagem Celular , Relação Dose-Resposta a Droga , Eletrofisiologia , Engenharia Genética , Humanos , Hiperinsulinismo/patologia , Hipoglicemia/patologia , Lactente , Secreção de Insulina , Ilhotas Pancreáticas/efeitos dos fármacos , Ilhotas Pancreáticas/metabolismo , Potenciais da Membrana/efeitos dos fármacos , Camundongos , Canais de Potássio/genética , Cloreto de Potássio/farmacologia , Receptores de Droga/genética , Proteínas Recombinantes de Fusão/genética , Receptores de Sulfonilureias , Tolbutamida/farmacologia , Transativadores/genética , Transfecção , Células Tumorais CultivadasRESUMO
Of the several pesticides used in the pest management strategy for cotton, endosulfan is ranked as having the greatest impact on the riverine ecosystem. A survey of changes in the densities of six abundant macroinvertebrate taxa (ephemeropteran nymphs Jappa kutera, Atalophlebia australis, Tasmanocoenis sp., and Baetis sp. and two trichopteran larvae, Cheumatopsyche sp. and Ecnomus sp.) between upstream and downstream zones of the cotton-growing region in the Namoi River was conducted between November 1995 and February 1996. In November and December 1995, there were few differences in population densities between all sites. In January and February 1996, population densities of the study taxa increased 7- to 10-fold higher at the two reference sites, with low concentrations of endosulfan in sediment and in passive samplers placed in the water column. In contrast, densities of these taxa at sites with exposure to 25-fold higher concentrations of endosulfan remained static and were between one and two orders of magnitude lower than densities at the reference sites in January and February. Population densities of Baetis sp., a mobile ephemeropteran, did not indicate any inverse relationship with endosulfan concentrations. Multivariate redundancy analysis indicated that endosulfan concentrations were the leading environmental predictor of changes in density of the five benethic taxa. Laboratory 48-h LC50 values of technical endosulfan in river water were 0.6, 1.3, and 0.4 ppb for early-instar nymphs of A. australis and J. kutera, and larvae of Cheumatopsyche sp., respectively. Endosulfan sulfate formed a large proportion of the total endosulfan concentrations measured from in situ passive samplers, indicating that its main route of entry into the river is through surface runoff during storm events.