Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 155
Filtrar
1.
BJOG ; 125(2): 119-129, 2018 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-27704677

RESUMO

OBJECTIVE: Stillbirths are among the most common adverse pregnancy outcomes, with 98% occurring in low-income countries. More than one-third occur in sub-Saharan Africa (SSA). However, the medical conditions causing stillbirths and interventions to reduce stillbirths from these conditions are not well documented. We estimated the reductions in stillbirths possible with combinations of interventions. DESIGN: We developed a computerised model to estimate the impact of various interventions on stillbirths caused by the most common conditions. The model considered the location of obstetric care (home, clinic or hospital) and each intervention's efficacy, penetration and utilisation. Maternal transfers were also considered. SETTING AND POPULATION: Pregnancies in SSA in 2012. METHODS: For each condition, we created a series of scenarios involving different combinations of interventions and modelled their impact on stillbirth rates. MAIN OUTCOME MEASURES: Stillbirths associated with various maternal and fetal conditions and the percentage reduction with various interventions. RESULTS: Eight to ten maternal and fetal conditions were responsible for most stillbirths, but none for more than 15%. The most common conditions causing stillbirths in SSA include obstructed labour and uterine rupture, fetal distress and umbilical cord complications, fetal growth restriction, pre-eclampsia/eclampsia, and placental abruption/placenta praevia. Syphilis and malaria contribute smaller numbers. Reducing stillbirths requires appropriate diagnosis and management of each condition, usually including hospital care for monitoring and delivery, often by caesarean section. Maternal syphilis and malaria were the only conditions for which outpatient management alone reduced stillbirth. CONCLUSIONS: Most stillbirths in low-income countries occur at term and during labour and therefore are preventable by appropriate obstetric care. Management focused on the maternal and fetal conditions that cause stillbirths is necessary to achieve stillbirth rates approaching those found in high-income countries. TWEETABLE ABSTRACT: Reducing stillbirth incidence requires appropriate management of each causative condition and often caesarean delivery.


Assuntos
Serviços de Saúde Materna , Modelos Teóricos , Avaliação de Resultados em Cuidados de Saúde , Cuidado Pré-Natal , Natimorto/epidemiologia , África Subsaariana/epidemiologia , Feminino , Humanos , Complicações do Trabalho de Parto/prevenção & controle , Gravidez , Complicações na Gravidez/prevenção & controle , Resultado da Gravidez
2.
Ultrasound Obstet Gynecol ; 52(6): 757-762, 2018 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-29155504

RESUMO

OBJECTIVE: To evaluate whether the presence of cervical funneling or intra-amniotic debris identified in the second trimester is associated with a higher rate of preterm birth (PTB) in asymptomatic nulliparous pregnant women with a midtrimester cervical length (CL) less than 30 mm (i.e. below the 10th percentile). METHODS: This was a secondary cohort analysis of data from a multicenter trial in nulliparous women between 16 and 22 weeks' gestation with a singleton gestation and CL less than 30 mm on transvaginal ultrasound, randomized to treatment with either 17-alpha-hydroxyprogesterone caproate or placebo. Sonographers were centrally certified in CL measurement, as well as in identification of intra-amniotic debris and cervical funneling. Univariable and multivariable analysis was performed to assess the associations of cervical funneling and intra-amniotic debris with PTB. RESULTS: Of the 657 women randomized, 112 (17%) had cervical funneling only, 33 (5%) had intra-amniotic debris only and 45 (7%) had both on second-trimester ultrasound. Women with either of these findings had a shorter median CL than those without (21.0 mm vs 26.4 mm; P < 0.001). PTB prior to 37 weeks was more likely in women with cervical funneling (37% vs 21%; odds ratio (OR), 2.2 (95% CI, 1.5-3.3)) or intra-amniotic debris (35% vs 23%; OR, 1.7 (95% CI, 1.1-2.9)). Results were similar for PTB before 34 and before 32 weeks' gestation. After multivariable adjustment that included CL, PTB < 34 and < 32 weeks continued to be associated with the presence of intra-amniotic debris (adjusted OR (aOR), 1.85 (95% CI, 1.00-3.44) and aOR, 2.78 (95% CI, 1.42-5.45), respectively), but not cervical funneling (aOR, 1.17 (95% CI, 0.63-2.17) and aOR, 1.45 (95% CI, 0.71-2.96), respectively). CONCLUSIONS: Among asymptomatic nulliparous women with midtrimester CL less than 30 mm, the presence of intra-amniotic debris, but not cervical funneling, is associated with an increased risk for PTB before 34 and 32 weeks' gestation, independently of CL. Copyright © 2017 ISUOG. Published by John Wiley & Sons Ltd.


Assuntos
17-alfa-Hidroxiprogesterona/uso terapêutico , Líquido Amniótico/química , Colo do Útero/diagnóstico por imagem , Nascimento Prematuro/epidemiologia , Ultrassonografia Pré-Natal/métodos , Adulto , Medida do Comprimento Cervical , Estudos de Coortes , Feminino , Humanos , Idade Materna , Gravidez , Segundo Trimestre da Gravidez , Nascimento Prematuro/etiologia , Ensaios Clínicos Controlados Aleatórios como Assunto , Adulto Jovem
3.
BJOG ; 123(5): 682-90, 2016 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-26663620

RESUMO

BACKGROUND: Preterm birth complicates almost all triplet pregnancies and no preventive strategy has proven effective. OBJECTIVE: To determine, using individual patient data (IPD) meta-analysis, whether the outcome of triplet pregnancy is affected by prophylactic administration of 17-hydroxyprogesterone caproate (17OHPc). SEARCH STRATEGY: We searched literature databases, trial registries and references in published articles. SELECTION CRITERIA: Randomised controlled trials (RCTs) of progestogens versus control that included women with triplet pregnancies. DATA COLLECTION AND ANALYSIS: Investigators from identified RCTs collaborated on the protocol and contributed their IPD. The primary outcome was a composite measure of adverse perinatal outcome. The secondary outcome was the rate of birth before 32 weeks of gestation. Other pre-specified outcomes included randomisation-to-delivery interval and rates of birth at <24, <28 and <34 weeks of gestation. MAIN RESULTS: Three RCTs of 17OHPc versus placebo included 232 mothers with triplet pregnancies and their 696 offspring. Risk-of-bias scores and between-study heterogeneity were low. Baseline characteristics were comparable between 17OHPc and placebo groups. The rate of the composite adverse perinatal outcome was similar among those treated with 17OHPc and those treated with placebo (34 and 35%, respectively; risk ratio [RR] 0.98, 95% confidence interval [95% CI] 0.79-1.2). The rate of birth at <32 weeks was also similar in the two groups (35 and 38%, respectively; RR 0.92, 95% CI 0.55-1.56). There were no significant between-group differences in perinatal mortality rate, randomisation-to-delivery interval, or other specified outcomes. CONCLUSION: Prophylactic 17OHPc given to mothers with triplet pregnancies had no significant impact on perinatal outcome or pregnancy duration. TWEETABLE ABSTRACT: 17-Hydroxyprogesterone caproate had no significant impact on the outcome or duration of triplet pregnancy.


Assuntos
Hidroxiprogesteronas/uso terapêutico , Gravidez de Trigêmeos , Nascimento Prematuro/prevenção & controle , Progestinas/uso terapêutico , Caproato de 17 alfa-Hidroxiprogesterona , Feminino , Humanos , Gravidez , Resultado do Tratamento
4.
BJOG ; 122(10): 1387-94, 2015 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-25600430

RESUMO

OBJECTIVE: To determine whether ß2 -adrenoceptor (ß2 AR) genotype is associated with shortening of the cervix or with preterm birth (PTB) risk among women with a short cervix in the second trimester. DESIGN: A case-control ancillary study to a multicentre randomised controlled trial. SETTING: Fourteen participating centres of the Maternal-Fetal Medicine Units Network of the Eunice Kennedy Shriver National Institute of Child Health and Human Development. POPULATION: Four hundred thirty-nine women, including 315 with short cervix and 124 with normal cervical length. METHODS: Nulliparous women with cervical length <30 mm upon a 16-22-week transvaginal sonogram and controls frequency-matched for race/ethnicity with cervical lengths ≥40 mm were studied. ß2 AR genotype was determined at positions encoding for amino acid residues 16 and 27. MAIN OUTCOME MEASURES: Genotype distributions were compared between case and control groups. Within the short cervix group, pregnancy outcomes were compared by genotype, with a primary outcome of PTB <37 weeks. RESULTS: Genotype data were available at position 16 for 433 women and at position 27 for 437. Using a recessive model testing for association between short cervix and genotype, and adjusted for ethnicity, there was no statistical difference between cases and controls for Arg16 homozygosity (OR 0.7, 95% CI 0.4-1.3) or Gln27 homozygosity (OR 0.9, 95% CI 0.3-2.7). Among cases, Arg16 homozygosity was not associated with protection from PTB or spontaneous PTB. Gln27 homozygosity was not associated with PTB risk, although sample size was limited. CONCLUSIONS: ß2 AR genotype does not seem to be associated with short cervical length or with PTB following the second-trimester identification of a short cervix. Influences on PTB associated with ß2 AR genotype do not appear to involve a short cervix pathway.


Assuntos
Genótipo , Nascimento Prematuro/etiologia , Receptores Adrenérgicos beta 2/genética , Incompetência do Colo do Útero/genética , Adulto , Estudos de Casos e Controles , Medida do Comprimento Cervical , Feminino , Marcadores Genéticos , Homozigoto , Humanos , Polimorfismo de Nucleotídeo Único , Gravidez , Segundo Trimestre da Gravidez , Estudos Prospectivos , Incompetência do Colo do Útero/diagnóstico por imagem
5.
BJOG ; 122(1): 27-37, 2015 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-25145491

RESUMO

BACKGROUND: In twin pregnancies, the rates of adverse perinatal outcome and subsequent long-term morbidity are substantial, and mainly result from preterm birth (PTB). OBJECTIVES: To assess the effectiveness of progestogen treatment in the prevention of neonatal morbidity or PTB in twin pregnancies using individual participant data meta-analysis (IPDMA). SEARCH STRATEGY: We searched international scientific databases, trial registration websites, and references of identified articles. SELECTION CRITERIA: Randomised clinical trials (RCTs) of 17-hydroxyprogesterone caproate (17Pc) or vaginally administered natural progesterone, compared with placebo or no treatment. DATA COLLECTION AND ANALYSIS: Investigators of identified RCTs were asked to share their IPD. The primary outcome was a composite of perinatal mortality and severe neonatal morbidity. Prespecified subgroup analyses were performed for chorionicity, cervical length, and prior spontaneous PTB. MAIN RESULTS: Thirteen trials included 3768 women and their 7536 babies. Neither 17Pc nor vaginal progesterone reduced the incidence of adverse perinatal outcome (17Pc relative risk, RR 1.1; 95% confidence interval, 95% CI 0.97-1.4, vaginal progesterone RR 0.97; 95% CI 0.77-1.2). In a subgroup of women with a cervical length of ≤25 mm, vaginal progesterone reduced adverse perinatal outcome when cervical length was measured at randomisation (15/56 versus 22/60; RR 0.57; 95% CI 0.47-0.70) or before 24 weeks of gestation (14/52 versus 21/56; RR 0.56; 95% CI 0.42-0.75). AUTHOR'S CONCLUSIONS: In unselected women with an uncomplicated twin gestation, treatment with progestogens (intramuscular 17Pc or vaginal natural progesterone) does not improve perinatal outcome. Vaginal progesterone may be effective in the reduction of adverse perinatal outcome in women with a cervical length of ≤25 mm; however, further research is warranted to confirm this finding.


Assuntos
Hidroxiprogesteronas/uso terapêutico , Doenças do Recém-Nascido/prevenção & controle , Morte Perinatal/prevenção & controle , Gravidez de Gêmeos , Nascimento Prematuro/prevenção & controle , Progesterona/uso terapêutico , Progestinas/uso terapêutico , Caproato de 17 alfa-Hidroxiprogesterona , Administração Intravaginal , Adulto , Displasia Broncopulmonar/prevenção & controle , Hemorragia Cerebral/prevenção & controle , Medida do Comprimento Cervical , Colo do Útero/diagnóstico por imagem , Enterocolite Necrosante/prevenção & controle , Feminino , Humanos , Recém-Nascido , Gravidez , Síndrome do Desconforto Respiratório do Recém-Nascido/prevenção & controle , Resultado do Tratamento
6.
Am J Perinatol ; 32(12): 1126-32, 2015 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-26445141

RESUMO

OBJECTIVE: The aim of the study is to evaluate the association of steroid metabolism and respiratory gene polymorphisms in neonates exposed to antenatal corticosteroids (ACS) with respiratory outcomes, small for gestational age (SGA), and response to repeat ACS. STUDY DESIGN: This candidate gene study is a secondary analysis of women enrolled in a randomized controlled trial of single versus weekly courses of ACS. Nineteen single nucleotide polymorphisms (SNPs) in 13 steroid metabolism and respiratory function genes were evaluated. DNA was extracted from placenta or fetal cord serum and analyzed with TaqMan genotyping. Each SNP was evaluated for association via logistic regression with respiratory distress syndrome (RDS), continuous positive airway pressure (CPAP)/ventilator use (CPV), and SGA. RESULTS: CRHBP, CRH, and CRHR1 minor alleles were associated with an increased risk of SGA. HSD11B1 and SCNN1B minor alleles were associated with an increased likelihood of RDS. Carriage of minor alleles in SerpinA6 was associated with an increased risk of CPV. CRH and CRHR1 minor alleles were associated with a decreased likelihood of CPV. CONCLUSION: Steroid metabolism and respiratory gene SNPs are associated with respiratory outcomes and SGA in patients exposed to ACS. Risks for respiratory outcomes are affected by minor allele carriage as well as by treatment with multiple ACS.


Assuntos
Corticosteroides/administração & dosagem , Corticosteroides/efeitos adversos , Recém-Nascido Pequeno para a Idade Gestacional , Polimorfismo de Nucleotídeo Único , Nascimento Prematuro/induzido quimicamente , Síndrome do Desconforto Respiratório do Recém-Nascido/prevenção & controle , Adulto , Feminino , Genótipo , Idade Gestacional , Humanos , Recém-Nascido , Modelos Logísticos , Masculino , Gravidez , Testes de Função Respiratória
7.
Am J Respir Cell Mol Biol ; 46(4): 470-8, 2012 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-22052878

RESUMO

Exposure of mice to hyperoxia produces pulmonary toxicity similar to acute lung injury/acute respiratory distress syndrome, but little is known about the interactions within the cardiopulmonary system. This study was designed to characterize the cardiopulmonary response to hyperoxia, and to identify candidate susceptibility genes in mice. Electrocardiogram and ventilatory data were recorded continuously from 4 inbred and 29 recombinant inbred strains during 96 hours of hyperoxia (100% oxygen). Genome-wide linkage analysis was performed in 27 recombinant inbred strains against response time indices (TIs) calculated from each cardiac phenotype. Reductions in minute ventilation, heart rate (HR), low-frequency (LF) HR variability (HRV), high-frequency HRV, and total power HRV were found in all mice during hyperoxia exposure, but the lag time before these changes began was strain dependent. Significant (chromosome 9) or suggestive (chromosomes 3 and 5) quantitative trait loci were identified for the HRTI and LFTI. Functional polymorphisms in several candidate susceptibility genes were identified within the quantitative trait loci and were associated with hyperoxia susceptibility. This is the first study to report highly significant interstrain variation in hyperoxia-induced changes in minute ventilation, HR, and HRV, and to identify polymorphisms in candidate susceptibility genes that associate with cardiac responses. Results indicate that changes in HR and LF HRV could be important predictors of subsequent adverse outcome during hyperoxia exposure, specifically the pathogenesis of acute lung injury. Understanding the genetic mechanisms of these responses may have significant diagnostic clinical value.


Assuntos
Lesão Pulmonar Aguda/etiologia , Lesão Pulmonar Aguda/genética , Frequência Cardíaca/genética , Hiperóxia/complicações , Animais , Ligação Genética , Hiperóxia/fisiopatologia , Pulmão/patologia , Camundongos , Camundongos Endogâmicos , Fenótipo , Proteínas/metabolismo , Locos de Características Quantitativas
8.
BJOG ; 119(13): 1617-23, 2012 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-23078336

RESUMO

OBJECTIVE: To determine whether vitamin D status is associated with recurrent preterm birth, and any interactions between vitamin D levels and fish consumption. DESIGN: A nested case-control study, using data from a randomised trial of omega-3 fatty acid supplementation to prevent recurrent preterm birth. SETTING: Fourteen academic health centres in the USA. POPULATION: Women with prior spontaneous preterm birth. METHODS: In 131 cases (preterm delivery at <35 weeks of gestation) and 134 term controls, we measured serum 25-hydroxyvitamin D [25(OH)D] concentrations by liquid chromatography-tandem mass spectrometry (LC-MS) from samples collected at baseline (16-22 weeks of gestation). Logistic regression models controlled for study centre, maternal age, race/ethnicity, number of prior preterm deliveries, smoking status, body mass index, and treatment. MAIN OUTCOME MEASURES: Recurrent preterm birth at <37 and <32 weeks of gestation. RESULTS: The median mid-gestation serum 25(OH)D concentration was 67 nmol/l, and 27% had concentrations of <50 nmol/l. Serum 25(OH)D concentration was not significantly associated with preterm birth (OR 1.33; 95% CI 0.48-3.70 for lowest versus highest quartiles). Likewise, comparing women with 25(OH)D concentrations of 50 nmol/l, or higher, with those with <50 nmol/l generated an odds ratio of 0.80 (95% CI 0.38-1.69). Contrary to our expectation, a negative correlation was observed between fish consumption and serum 25(OH)D concentration (-0.18, P < 0.01). CONCLUSIONS: In a cohort of women with a prior preterm birth, vitamin D status at mid-pregnancy was not associated with recurrent preterm birth.


Assuntos
Dieta , Nascimento Prematuro/etiologia , Fenômenos Fisiológicos da Nutrição Pré-Natal , Alimentos Marinhos , Deficiência de Vitamina D/complicações , Vitamina D/análogos & derivados , Adulto , Biomarcadores/sangue , Estudos de Casos e Controles , Cromatografia Líquida , Inquéritos sobre Dietas , Feminino , Humanos , Modelos Logísticos , Espectrometria de Massas , Gravidez , Nascimento Prematuro/sangue , Estudos Prospectivos , Recidiva , Risco , Autorrelato , Vitamina D/sangue , Deficiência de Vitamina D/sangue
9.
Exp Dermatol ; 19(6): 518-26, 2010 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-20100190

RESUMO

Hair loss (alopecia) can result from a variety of metabolic, endocrine, immunologic, and environmental causes. This investigation was undertaken to determine the mechanisms underlying the sporadic development of alopecia in litters from C57BL/6 interleukin-10-deficient (Il10(-/-)) mice. All pups in affected litters demonstrated alopecia by postnatal days 17-19, with hair loss from their trunks but not from their head, base of tail, or feet. Histopathology revealed distorted hair follicles containing broken hair shafts and prominent dermal infiltrates containing increased numbers of activated mast cells. Hair re-growth began soon after weaning, suggesting that the alopecia was triggered by factors transmitted during lactation. Milk from Il10(-/-) dams induced macrophage secretion of pro-inflammatory cytokines in vitro regardless of whether or not their pups developed alopecia. Feeding dams a diet containing 3-6 ppm iron increased the percentage of litters with alopecia to 100% for pups with mast cells, with 0% alopecia in mast cell-deficient pups. When dams were fed a diet containing 131 ppm iron, significantly lower haemoglobin and hematocrit values were observed in pups from litters with alopecia (71%; 5 of 7 litters) compared to litters without alopecia. Genetic or pharmacologic inhibition of c-kit that resulted in depletion of mast cells in pups prevented hair loss in at-risk litters. These studies demonstrate that maternal iron-restricted diets enhance the incidence of alopecia in IL-10-deficient mouse pups and suggest mast cells as potential effector cells. Further studies are indicated to further explore the mechanisms involved and to determine how mast cells may contribute to alopecia in humans.


Assuntos
Alopecia/etiologia , Interleucina-10/deficiência , Deficiências de Ferro , Proteínas Proto-Oncogênicas c-kit/genética , Alopecia/genética , Alopecia/patologia , Anemia/complicações , Anemia/patologia , Animais , Animais Lactentes , Anticorpos Monoclonais/imunologia , Anticorpos Monoclonais/farmacologia , Degranulação Celular , Linhagem Celular , Quimiocinas/metabolismo , Citocinas/metabolismo , Dieta , Feminino , Folículo Piloso/patologia , Interleucina-10/genética , Ativação de Macrófagos/imunologia , Macrófagos/imunologia , Macrófagos/metabolismo , Masculino , Mastócitos/efeitos dos fármacos , Mastócitos/patologia , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Endogâmicos , Camundongos Mutantes , Leite/imunologia , Gravidez , Proteínas Proto-Oncogênicas c-kit/imunologia , Pele/patologia
11.
Sex Plant Reprod ; 22(3): 153-65, 2009 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-20033436

RESUMO

The Australian midge orchid Corunastylis apostasioides of the tribe Diurideae has completely eliminated any male contribution in the process of seed formation, which occurs directly from the maternal tissue by a process termed apomixis. Here, we report C. apostasioides to be an obligate apomictic species devoid of any sexuality and compare its development to a close sexual relative C. fimbriata (R. Br.) D.L. Jones & M.A. Clem. Apomictic characteristics in C. apostasioides include production of seed in absence of fertilization, frequently closed flowers, production of immature pollen in non-dehiscent anthers, expansion of ovaries despite the lack of fertilization and the absence of a citronella scent that is found in C. fimbriata produced to attract pollinating vinegar flies (Jones 2006). The nature of apomixis in C. apostasioides was examined by ovule histology and amplified fragment length polymorphism (AFLP) in each case drawing comparison with sexual C. fimbriata. In C. apostasioides the central megaspore mother cell undergoes diplosporic apomixis, while additional embryos are derived from nucellar or integument initials formed by sporophytic apomixis. Typical of apomicts, C. apostasioides is polyploid compared to the sexual C. fimbriata. The divergences of C. apostasioides from sexuality to apomictic development are discussed.


Assuntos
Fertilização , Violaceae/fisiologia , Análise do Polimorfismo de Comprimento de Fragmentos Amplificados , Flores/anatomia & histologia , Flores/genética , Flores/crescimento & desenvolvimento , Flores/fisiologia , Regulação da Expressão Gênica de Plantas , Violaceae/anatomia & histologia , Violaceae/genética , Violaceae/crescimento & desenvolvimento
12.
Science ; 279(5355): 1371-3, 1998 Feb 27.
Artigo em Inglês | MEDLINE | ID: mdl-9478901

RESUMO

Transcription of the AUX/IAA family of genes is rapidly induced by the plant hormone auxin, but evidence that AUX/IAA genes mediate further responses to auxin has been elusive. Changes in diverse auxin responses result from mutations in the Arabidopsis AXR3 gene. AXR3 was shown to be a member of the AUX/IAA family, providing direct evidence that AUX/IAA genes are central in auxin signaling. Molecular characterization of axr3 gain-of-function and loss-of-function mutations established the functional importance of domains conserved among AUX/IAA proteins.


Assuntos
Proteínas de Arabidopsis , Arabidopsis/genética , Genes de Plantas , Ácidos Indolacéticos/fisiologia , Proteínas Nucleares/genética , Proteínas de Plantas/genética , Sequência de Aminoácidos , Arabidopsis/fisiologia , Mapeamento Cromossômico , Clonagem Molecular , Dados de Sequência Molecular , Mutação , Proteínas Nucleares/química , Proteínas Nucleares/fisiologia , Fenótipo , Proteínas de Plantas/química , Proteínas de Plantas/fisiologia , Mutação Puntual , Splicing de RNA , Transdução de Sinais , Supressão Genética , Fatores de Transcrição
13.
J Clin Invest ; 76(2): 630-6, 1985 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-4031067

RESUMO

Proximal convoluted (S2) and straight (S3) renal tubule segments were studied to determine the effect of Ca on lumen-to-bath phosphate flux (JlbPO4). Increasing bath and perfusate Ca from 1.8 to 3.6 mM enhanced JlbPO4 from 3.3 +/- 0.7 to 6.6 +/- 0.6 pmol/mm per min in S2 segments (P less than 0.001) but had no effect in S3 segments. Decreasing bath and perfusate Ca from 1.8 to 0.2 mM reduced JlbPO4 from 3.7 +/- 0.6 to 2.2 +/- 0.6 in S2 segments. These effects were unrelated to changes in fluid absorption and transepithelial potential difference. Increasing cytosolic Ca with a Ca ionophore, inhibiting the Ca-calmodulin complex with trifluoperazine, or applying the Ca channel blocker nifedipine had no effect on JlBPO4 in S2 segments. Increasing only bath Ca from 1.8 to 3.6 mM did not significantly affect JlbPO4. However, increasing only perfusate Ca enhanced JlbPO4 from 3.4 +/- 0.7 to 6.1 +/- 0.7 pmol/mm per min (P less than 0.005). Inhibition of hydrogen ion secretion, by using a low bicarbonate, low pH perfusate, both depressed base-line JlbPO4 and abolished the stimulatory effect of raising perfusate Ca. Net phosphate efflux (JnetPO4) also increased after ambient calcium levels were raised, ruling out a significant increase in PO4 backflux. When net sodium transport was abolished by reducing the bath temperature to 24 degrees C, JnetPO4 at normal ambient calcium was reduced and increasing ambient calcium failed to increase it, ruling out a simple physicochemical reaction wherein phosphate precipitates out of solution with calcium. The present studies provide direct evidence for a stimulatory effect of Ca on sodium-dependent PO4 absorption in the proximal convoluted tubule, exerted at the luminal membrane. It is postulated that Ca modulates the affinity of the PO4 transporter for the anion.


Assuntos
Cálcio/farmacologia , Túbulos Renais Proximais/metabolismo , Fosfatos/metabolismo , Absorção , Animais , Feminino , Taxa de Filtração Glomerular , Concentração de Íons de Hidrogênio , Túbulos Renais Proximais/efeitos dos fármacos , Matemática , Coelhos
14.
J Clin Invest ; 65(1): 37-42, 1980 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-6243139

RESUMO

Unidirectional calcium flux (JCa) in the superficial pars recta and thin descending limb of Henle (DLH) was examined by the isolated tubule microperfusion technic using 45Ca as the isotopic tracer. In the pars recta sequential measurements of lumen-to-bath flux (JlbCa) and bath-to-lumen flux (JblCa) revealed: JlbCa 22.4 +/- 4.18, JblCa 7.97 +/- 1.95, and calculated net efflux of calcium (JnetCa 13.0 +/- 1.74 peq min-1 mm-u. To measure JnetCa directly, 45Ca of identical specific activity was used to bathe and perfuse the tubule. These studies revealed: JlbCa 14.1 +/- 1.33, JnetCa 11.2 +/- 1.15, and calculated JblCa 2.91 +/- 0.49 peq min-1 mm-1. The addition of ouabain (10 microM) resulted in a rise in potential difference and a fall in water absorption, but not a statistically significant change in JnetCa. Tubules studies at 25 degrees C bath temperature, showed no significant JnetCa, and upon heating the bath to 37 degrees C, showed JnetCa of 3.75--5.00 peg min-1 mm-1. Unidirectional and net efflux studies in six DLH showed no significant transport of calcium. These studies demonstrate substantial active absorption of calcium by the superficial pars recta, which is not inhibitable by ouabain but is inhibited by lowering bath temperature to 25 degrees C. No significant calcium transport was found in the DLH using identical technics.


Assuntos
Cálcio/metabolismo , Túbulos Renais Proximais/metabolismo , Túbulos Renais/metabolismo , Alça do Néfron/metabolismo , Animais , Transporte Biológico Ativo/efeitos dos fármacos , Temperatura Baixa , Feminino , Técnicas In Vitro , Túbulos Renais Proximais/efeitos dos fármacos , Alça do Néfron/efeitos dos fármacos , Ouabaína/farmacologia , Perfusão , Coelhos , ATPase Trocadora de Sódio-Potássio/antagonistas & inibidores
15.
J Clin Invest ; 74(3): 834-42, 1984 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-6236233

RESUMO

Calcium transport was studied in isolated S2 segments of rabbit superficial proximal convoluted tubules. 45Ca was added to the perfusate for measurement of lumen-to-bath flux (JlbCa), to the bath for bath-to-lumen flux (JblCa), and to both perfusate and bath for net flux (JnetCa). In these studies, the perfusate consisted of an equilibrium solution that was designed to minimize water flux or electrochemical potential differences (PD). Under these conditions, JlbCa (9.1 +/- 1.0 peq/mm X min) was not different from JblCa (7.3 +/- 1.3 peq/mm X min), and JnetCa was not different from zero, which suggests that calcium transport in the superficial proximal convoluted tubule is due primarily to passive transport. The efflux coefficient was 9.5 +/- 1.2 X 10(-5) cm/s, which was not significantly different from the influx coefficient, 7.0 +/- 1.3 X 10(-5) cm/s. When the PD was made positive or negative with use of different perfusates, net calcium absorption or secretion was demonstrated, respectively, which supports a major role for passive transport. These results indicate that in the superficial proximal convoluted tubule of the rabbit, passive driving forces are the major determinants of calcium transport.


Assuntos
ATPases Transportadoras de Cálcio/metabolismo , Cálcio/metabolismo , Túbulos Renais Proximais/fisiologia , Animais , Transporte Biológico Ativo , Radioisótopos de Cálcio , Técnicas In Vitro , Túbulos Renais Proximais/metabolismo , Cinética , Matemática , Potenciais da Membrana , Modelos Biológicos , Perfusão , Coelhos
16.
J Clin Invest ; 48(10): 1888-94, 1969 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-5822594

RESUMO

To examine the specific effect of extracellular fluid (ECF) volume expansion on phosphate excretion studies were performed in thyroparathyroidectomized dogs receiving saline solution intravenously. The natriuresis resulting from ECF volume expansion was consistently accompanied by an increase in phosphate excretion. The possible role of increased filtered load of phosphate was eliminated in experiments in which the filtered load of phosphate was reduced by acute reduction in the glomerular filtration rate. Despite considerable reductions in filtered phosphate, ECF volume expansion resulted in a consistent increase in phosphate excretion. Furthermore, the possible contribution of alteration in blood composition was investigated in experiments in which saline was infused during thoracic inferior vena cava constriction. In these experiments saline infusion failed to increase sodium or phosphate excretion. Cessation of saline infusion and release of caval constriction resulted in a prompt natriuresis and increased phosphate excretion. It is concluded from these studies that extracellular fluid volume expansion results in an increased phosphate excretion in the parathyroidectomized dog. This effect is the specific consequence of ECF volume expansion and is not due to increase in the filtered load of phosphate or alterations in blood composition.


Assuntos
Espaço Extracelular , Rim/metabolismo , Fosfatos/metabolismo , Fosfatos/urina , Animais , Cães , Taxa de Filtração Glomerular , Natriurese , Glândulas Paratireoides/cirurgia , Hormônio Paratireóideo/fisiologia , Potássio/urina , Sódio/metabolismo , Tireoidectomia , Água/metabolismo
17.
J Clin Invest ; 66(5): 1004-9, 1980 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-7430341

RESUMO

Calcium transport was studied in medullary and cortical segments of the thick ascending limb of Henle perfused in vitro. 45Ca was added to the perfusate for measuring lumen-to-bath flux (JlbCa), to the bath for measuring bath-to-lumen flux (JblCa), or to both perfusate and bath for measuring net flux (JnetCa). In the medullary segment JlbCa exceeding JblCa and the efflux:influx coefficient ratio was not different from the value predicted from the observed potential difference (PD). In the cortical segments, however, efflux:influx coefficient ratio was greater than the value predicted from the PD, suggesting that calcium transport in this segment may be active, while it is passive in the medullary segment. Furosemide, which reversibly decreases PD in both cortical and medullary segments, inhibited JlbCa only in the medullary segment. Parathyroid hormone (PTH), on the other hand, had no effect on JnetCa in the medullary segment, but it significantly augmented JnetCa in the cortical segment. These results indicate that calcium transport in the thick ascending limb is heterogeneous. In the medullary segment it is passive, inhibited by furosemide and not influenced by PTH. In the cortical segment, however, calcium transport appears to be active, not inhibited by furosemide and stimulated by PTH.


Assuntos
Cálcio/metabolismo , Túbulos Renais/metabolismo , Alça do Néfron/metabolismo , Animais , Transporte Biológico , Feminino , Furosemida/farmacologia , Alça do Néfron/efeitos dos fármacos , Hormônio Paratireóideo/farmacologia , Coelhos
18.
Obstet Gynecol ; 110(5): 977-85, 2007 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-17978107

RESUMO

OBJECTIVE: To assess tolerance and safety of 0.6% chlorhexidine vaginal and neonatal wipes to improve perinatal outcomes in home deliveries in Pakistan and the ability of traditional birth attendants and project staff to perform a randomized trial of this intervention. METHODS: Focus groups of pregnant and nonpregnant women and in-depth interviews of traditional birth attendants explored barriers to the use of chlorhexidine wipes. Then, a study was performed of women delivering at home attended by traditional birth attendants. Consenting women were randomly assigned to receive either 0.6% chlorhexidine or saline vaginal and neonatal wipes. Women and their infants were followed up on postpartum days 7, 14, and 28. Acceptability and tolerance of vaginal and neonatal wipes, as well as maternal and neonatal outcomes, were assessed. RESULTS: The focus groups and interviews indicated that the chlorhexidine intervention would be acceptable to women and their providers. Of the 213 eligible pregnant women approached, 203 (95%) gave informed consent and were enrolled and allocated to groups. Traditional birth attendants had no difficulty administering chlorhexidine vaginal and neonatal wipes in a home setting. Of the 203 births, 103 (51%) of whom received 0.6% chlorhexidine, there were no allergic reactions, vaginal itching, burning, or requests for study termination. Follow-up at 28 days postpartum was more than 95%. Although this study was not powered to show significant differences in neonatal outcomes between treatment groups, the lower rates of some neonatal adverse clinical outcomes in the chlorhexidine group were encouraging. CONCLUSION: Use of 0.6% chlorhexidine vaginal and neonatal wipes for the prevention of neonatal infection is well-tolerated and seems safe. A trial of this intervention by traditional birth attendants in a home-delivery setting is feasible. CLINICAL TRIAL REGISTRATION: ClinicalTrials.gov, www.clinicaltrials.gov, NCT00121394 LEVEL OF EVIDENCE: I.


Assuntos
Anti-Infecciosos Locais/uso terapêutico , Clorexidina/uso terapêutico , Parto Domiciliar/métodos , Adulto , Estudos de Viabilidade , Feminino , Grupos Focais , Humanos , Mortalidade Infantil , Recém-Nascido , Doenças do Recém-Nascido/prevenção & controle , Infecções/transmissão , Masculino , Tocologia , Paquistão/epidemiologia , Cooperação do Paciente , Projetos Piloto , Gravidez
19.
Phytopathology ; 97(7): 865-72, 2007 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-18943936

RESUMO

ABSTRACT Potato early dying (PED), also known as Verticillium wilt, caused by Verticillium dahliae, is a seasonal yield-limiting disease of potato worldwide, and PED-resistant cultivars currently represent only a small percentage of potato production. In this study, we developed a real-time quantitative polymerase chain reaction (Q-PCR) approach to detect and quantify V. dahliae. The efficiency of the designed primer pair VertBt-F/VertBt-R, derived from the sequence of the beta-tubulin gene, was greater than 95% in monoplex Q-PCR and duplex (using Plexor technology) procedures with primers PotAct-F/PotAct-R, obtained from the sequence of the actin gene, designed for potato. As few as 148 fg of V. dahliae DNA were detected and quantified, which is equivalent to five nuclei. Q-PCR detected V. dahliae in naturally infected air-dried potato stems and fresh stems of inoculated plants. Spearman correlations indicated a high correlation (upward of 80%) between V. dahliae quantifications using Q-PCR and the currently used plating assays. Moreover, Q-PCR substantially reduced the variability compared with that observed in the plating assay, and allowed for the detection of V. dahliae in 10% of stem samples found to be pathogen free on the culture medium. The described Q-PCR approach should provide breeders with a more sensitive and less variable alternative to time-consuming plating assays to distinguish response of breeding lines to colonization by V. dahliae.

20.
Plant Dis ; 91(4): 360-367, 2007 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-30781175

RESUMO

Verticillium wilt (Vw), caused by the soilborne fungi Verticillium dahliae and V. albo-atrum, is an important disease of potato (Solanum tuberosum). Host plant resistance is a promising method of Vw control. Culture-based methods that quantify the pathogen in host tissue often are used for Vw resistance screening. To evaluate the processing time, accuracy, and precision of these methods, 46 clones were planted in a field naturally infested with V. dahliae to collect data on visual disease symptoms, pathogen colonization, and yield. In 2002, disease severity explained 4.34% of the variability of yield loss, but the linear relationship between stem colonization and yield loss was not significant. In 2003, stem colonization explained 57.5% of the variability of yield loss, whereas disease severity explained 1.7% of the variability of yield loss. Correlations comparing clone ranks from repeated pathogen measurements indicated that culturing sap from individual stems or bulked stems generated more repeatable clone rankings than culturing dried stems. Clone rankings were more repeatable between years if pathogen measurements were made earlier in the growing season. The results indicate a need to characterize the effect of the environment on the relationship among pathogen population sizes in planta, disease symptoms, and yield loss.

SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA