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1.
Diagn Microbiol Infect Dis ; 105(4): 115889, 2023 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-36758251

RESUMO

We present an 18-year-old woman with a urinary tract infection caused by Salmonella Oranienburg. S. Oranienburg was isolated from her pet snake and confirmed as the source of infection using whole genome sequencing. Our case demonstrates the risk of acquiring reptile-associated salmonellosis and stretches the need for awareness to prevent these infections.


Assuntos
Salmonelose Animal , Infecções Urinárias , Humanos , Animais , Feminino , Adolescente , Zoonoses/prevenção & controle , Salmonelose Animal/diagnóstico , Salmonella/genética , Répteis , Infecções Urinárias/diagnóstico , Infecções Urinárias/tratamento farmacológico
2.
J Clin Virol ; 152: 105190, 2022 07.
Artigo em Inglês | MEDLINE | ID: mdl-35640402

RESUMO

BACKGROUND: Enterovirus-D68 (EV-D68) predominantly causes respiratory disease. However, EV-D68 infections also have been associated with central nervous system (CNS) complications, most specifically acute flaccid myelitis (AFM). Diagnosing EV-D68-associated CNS disease is challenging since viral RNA is rarely detected in cerebrospinal fluid (CSF). OBJECTIVE: In order to determine an EV antibody index (AI), we evaluated the value of a commercially available quantitative ELISA to detect EV-specific antibodies in paired CSF and blood. STUDY DESIGN: Nine paired CSF and blood samples were obtained from patients with EV-D68-associated AFM or from patients with a confirmed EV-associated CNS disease. EV-specific antibodies were detected using a quantitative ELISA. A Reiber diagram analysis was performed, by which the AI was calculated. Subsequently, EV ELISA results were compared with an EV-D68 virus neutralization test. RESULTS: ELISA detected EV-specific antibodies in 1 out of the 3 patients with EV-D68-associated AFM and in 3 out of the 6 patients with confirmed EV-associated CNS disease. In these patients, the AI was indicative for intrathecal antibody production against enterovirus. Assay comparison showed that EV-D68 neutralizing antibody detection increased the sensitivity of EV-D68 antibody detection. CONCLUSIONS: A quantitative EV IgG ELISA in combination with Reiber diagram analysis and AI-calculation can be used as a diagnostic tool for EV-associated CNS disease, including EV-D68. An EV-D68 specific ELISA will improve the sensitivity of the tool. With the growing awareness that the detection of non-polio enteroviruses needs to be improved, diagnostic laboratories should consider implementation of EV serology.


Assuntos
Viroses do Sistema Nervoso Central , Enterovirus Humano D , Infecções por Enterovirus , Mielite , Antígenos Virais , Sistema Nervoso Central , Viroses do Sistema Nervoso Central/diagnóstico , Enterovirus Humano D/genética , Infecções por Enterovirus/complicações , Humanos , Mielite/diagnóstico , Doenças Neuromusculares
4.
Pediatr Infect Dis J ; 39(4): 267-272, 2020 04.
Artigo em Inglês | MEDLINE | ID: mdl-32097245

RESUMO

BACKGROUND: Limited data are available on childhood encephalitis. Our study aimed to increase insight on clinical presentation, etiology, and clinical outcome of children with severe encephalitis in the Netherlands. METHODS: We identified patients through the Dutch Pediatric Intensive Care Evaluation database and included children diagnosed with encephalitis <18 years of age admitted to 1 of the 8 pediatric intensive care units (PICU) in the Netherlands between January 2003 and December 2013. We analyzed demographic characteristics, clinical symptoms, neurologic imaging, etiology, treatment and mortality. RESULTS: We included 121 children with a median age of 4.6 years (IQR 1.3-9.8). The most frequently described clinical features were headache (82.1%), decreased consciousness (79.8%) and seizures (69.8%). In 44.6% of the children, no causative agent was identified. Viral- and immune-mediated encephalitis were diagnosed in 33.1% and 10.7% of the patients. A herpes simplex virus infection (13.2%) was mainly seen in children <5 years of age, median age, 1.73 years (IQR 0.77-5.01), while immune-mediated encephalitis mostly affected older children, median age of 10.4 years (IQR, 3.72-14.18). An age of ≥ 5 years at initial presentation was associated with a lower mortality (OR 0.2 [CI 0.08-0.78]). The detection of a bacterial (OR 9.4 [CI 2.18-40.46]) or viral (OR 3.7 [CI 1.16-11.73]) pathogen was associated with a higher mortality. CONCLUSIONS: In almost half of the Dutch children presenting with severe encephalitis, a causative pathogen could not be identified, underlining the need for enhancement of microbiologic diagnostics. The detection of a bacterial or viral pathogen was associated with a higher mortality.


Assuntos
Encefalite Viral/epidemiologia , Encefalite/epidemiologia , Encefalite/etiologia , Encefalite Infecciosa/epidemiologia , Unidades de Terapia Intensiva Pediátrica/estatística & dados numéricos , Criança , Pré-Escolar , Encefalite/mortalidade , Encefalite Viral/diagnóstico , Encefalite Viral/mortalidade , Feminino , Hospitalização/estatística & dados numéricos , Humanos , Lactente , Encefalite Infecciosa/diagnóstico , Encefalite Infecciosa/mortalidade , Masculino , Países Baixos/epidemiologia , Estudos Retrospectivos , Índice de Gravidade de Doença
5.
J Clin Virol ; 120: 17-19, 2019 11.
Artigo em Inglês | MEDLINE | ID: mdl-31521013

RESUMO

BACKGROUND: Diagnosis of human bocavirus 1 (HBoV1) has been based on qualitative PCRs detecting HBoV1 DNA or detection of HBoV1 mRNA. OBJECTIVE: This study aims to assess whether a rapid and automated HBoV1 antigen test is suitable for diagnosis of acute HBoV1 infection. STUDY DESIGN: HBoV1 antigen detection has been compared with quantitative HBoV1 DNA PCR and HBoV1 mRNA RT-PCR. RESULTS AND CONCLUSION: We conclude that HBoV1 antigen detection has higher clinical specificity and positive predictive value than HBoV1 DNA qualitative PCRs, yet a lower sensitivity than HBoV1 mRNA detection. Additionally, HBoV1 antigen detection is beneficial in its rapidity and availability as a point-of-care test.


Assuntos
Antígenos Virais/metabolismo , Bocavirus Humano/genética , Bocavirus Humano/imunologia , Infecções por Parvoviridae/diagnóstico , RNA Mensageiro/genética , Infecções Respiratórias/virologia , Automação , Criança , DNA Viral/genética , Feminino , Genótipo , Humanos , Masculino , Infecções por Parvoviridae/imunologia , Fenótipo , Sistemas Automatizados de Assistência Junto ao Leito , RNA Viral/genética , Infecções Respiratórias/imunologia , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Sensibilidade e Especificidade , Carga Viral
6.
Clin Infect Dis ; 69(7): 1243-1253, 2019 09 13.
Artigo em Inglês | MEDLINE | ID: mdl-30689772

RESUMO

We systematically reviewed available evidence from Embase, Medline, and the Cochrane Library on diagnostic accuracy and clinical impact of commercially available rapid (results <3 hours) molecular diagnostics for respiratory viruses as compared to conventional molecular tests. Quality of included studies was assessed using the Quality Assessment of Diagnostic Accuracy Studies criteria for diagnostic test accuracy (DTA) studies, and the Cochrane Risk of Bias Assessment and Risk of Bias in Nonrandomized Studies of Interventions criteria for randomized and observational impact studies, respectively. Sixty-three DTA reports (56 studies) were meta-analyzed with a pooled sensitivity of 90.9% (95% confidence interval [CI], 88.7%-93.1%) and specificity of 96.1% (95% CI, 94.2%-97.9%) for the detection of either influenza virus (n = 29), respiratory syncytial virus (RSV) (n = 1), influenza virus and RSV (n = 19), or a viral panel including influenza virus and RSV (n = 14). The 15 included impact studies (5 randomized) were very heterogeneous and results were therefore inconclusive. However, we suggest that implementation of rapid diagnostics in hospital care settings should be considered.


Assuntos
Técnicas de Diagnóstico Molecular , Infecções Respiratórias/diagnóstico , Infecções Respiratórias/virologia , Algoritmos , Tomada de Decisão Clínica , Gerenciamento Clínico , Humanos , Influenza Humana/diagnóstico , Influenza Humana/virologia , Técnicas de Diagnóstico Molecular/métodos , Técnicas de Diagnóstico Molecular/normas , Curva ROC , Reprodutibilidade dos Testes , Infecções por Vírus Respiratório Sincicial/diagnóstico , Infecções por Vírus Respiratório Sincicial/virologia , Sensibilidade e Especificidade
7.
Arch Virol ; 164(3): 799-806, 2019 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-30666460

RESUMO

Parechoviruses (PeVs) are highly prevalent viruses worldwide. Over the last decades, several studies have been published on PeV epidemiology in Europe, Asia and North America, while information on other continents is lacking. The aim of this study was to describe PeV circulation in a cohort of children in Malawi, Africa. A total of 749 stool samples obtained from Malawian children aged 6 to 60 months were tested for the presence of PeV by real-time PCR. We performed typing by phylogenetic and Basic Local Alignment Search Tool (BLAST) analysis. PeV was found in 57% of stool samples. Age was significantly associated with PeV positivity (p = 0.01). Typing by phylogenetic analysis resulted in 15 different types, while BLAST typing resulted in 14 different types and several indeterminate strains. In total, six strains showed inconsistencies in typing between the two methods. One strain, P02-4058, remained untypable by all methods, but appeared to belong to the recently reclassified PeV-A19 genotype. PeV-A1, -A2 and -A3 were the most prevalent types (26.8%, 13.8% and 9.8%, respectively). Both the prevalence and genetic diversity found in our study were remarkably high. Our data provide an important contribution to the scarce data available on PeV epidemiology in Africa.


Assuntos
Variação Genética , Parechovirus/isolamento & purificação , Infecções por Picornaviridae/virologia , Criança , Pré-Escolar , Estudos de Coortes , Fezes/virologia , Feminino , Genótipo , Humanos , Lactente , Malaui/epidemiologia , Masculino , Parechovirus/classificação , Parechovirus/genética , Filogenia , Infecções por Picornaviridae/epidemiologia
8.
Arch Virol ; 163(10): 2645-2653, 2018 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-29808442

RESUMO

Enteroviruses (EVs) are among the most commonly detected viruses infecting humans worldwide. Although the prevalence of EVs is widely studied, the status of EV prevalence in sub-Saharan Africa remains largely unknown. The objective of our present study was therefore to increase our knowledge on EV circulation in sub-Saharan Africa. We obtained 749 fecal samples from a cross-sectional study conducted on Malawian children aged 6 to 60 months. We tested the samples for the presence of EVs using real time PCR, and typed the positive samples based on partial viral protein 1 (VP1) sequences. A large proportion of the samples was EV positive (89.9%). 12.9% of the typed samples belonged to EV species A (EV-A), 48.6% to species B (EV-B) and 38.5% to species C (EV-C). More than half of the EV-C strains (53%) belonged to subgroup C containing, among others, Poliovirus (PV) 1-3. The serotype most frequently isolated in our study was CVA-13, followed by EV-C99. The strains of CVA-13 showed a vast genetic diversity, possibly representing a new cluster, 'F'. The majority of the EV-C99 strains grouped together as cluster B. In conclusion, this study showed a vast circulation of EVs among Malawian children, with an EV prevalence of 89.9%. Identification of prevalences for species EV-C comparable to our study (38.5%) have only previously been reported in sub-Saharan Africa, and EV-C is rarely found outside of this region. The data found in this study are an important contribution to our current knowledge of EV epidemiology within sub-Saharan Africa.


Assuntos
Enterovirus Humano C/isolamento & purificação , Infecções por Enterovirus/virologia , Proteínas do Capsídeo/genética , Proteínas do Capsídeo/metabolismo , Criança , Pré-Escolar , Estudos de Coortes , Estudos Transversais , Enterovirus Humano C/classificação , Enterovirus Humano C/genética , Infecções por Enterovirus/epidemiologia , Fezes/virologia , Feminino , Variação Genética , Genótipo , Humanos , Lactente , Malaui/epidemiologia , Masculino , Filogenia
9.
Pediatr Infect Dis J ; 37(10): e256-e257, 2018 10.
Artigo em Inglês | MEDLINE | ID: mdl-29561512

RESUMO

Human parechovirus infections usually cause mild symptoms in children. Although their contribution to severe disease in young children-such as neonatal sepsis and meningoencephalitis-is increasingly recognized, data on long-term consequences are scarce. Here we present the case of a 5-year-old boy with severe long-term neurodevelopmental sequelae after human parechovirus-3 meningitis.


Assuntos
Meningite/complicações , Meningite/virologia , Transtornos do Neurodesenvolvimento/etiologia , Parechovirus , Infecções por Picornaviridae/complicações , Pré-Escolar , Epilepsia , Humanos , Recém-Nascido Prematuro , Masculino , Sepse Neonatal , Transtornos do Neurodesenvolvimento/virologia
10.
Clin Infect Dis ; 65(11): 1959, 2017 11 13.
Artigo em Inglês | MEDLINE | ID: mdl-29020177

Assuntos
Vírus
11.
BMC Pregnancy Childbirth ; 17(1): 166, 2017 Jun 02.
Artigo em Inglês | MEDLINE | ID: mdl-28577352

RESUMO

BACKGROUND: Postpartum haemorrhage is a major obstetric risk worldwide. Therefore risk factors need to be investigated to control for this serious complication. A recent systematic review and meta-analysis revealed that the use of both serotonergic and non-serotonergic antidepressants in pregnancy are associated with a higher risk of postpartum haemorrhage. However, use of antidepressants in pregnancy is often necessary because untreated depression in pregnancy is associated with adverse maternal and neonatal outcome, such as postpartum depression, preterm birth and dysmaturity. Therefore it is of utmost importance to unravel the possible association between postpartum haemorrhage and the use of serotonergic and other psychopharmacological medication during pregnancy. METHODS: We performed a matched cohort observational study consecutively including all pregnant women using serotonergic medication (n = 578) or other psychopharmacological medication (n = 50) visiting two teaching hospitals in Amsterdam between 2010 and 2014. The incidence of postpartum haemorrhage in women using serotonergic medication or other psychopharmacological medication was compared with the incidence of postpartum haemorrhage in 641,364 pregnant women not using psychiatric medication selected from the database of the Netherlands Perinatal Registry foundation (Perined). Matching took place 1:5 for nine factors, i.e., parity, maternal age, ethnicity, socioeconomic status, macrosomia, gestational duration, history of postpartum haemorrhage, labour induction and hypertensive disorder. RESULTS: Postpartum haemorrhage occurred in 9.7% of the women using serotonergic medication. In the matched controls this was 6.6% (p = 0.01). The adjusted odds ratio (aOR) before matching was 1.6 (95% CI 1.2-2.1) and after matching 1.5 (95% CI 1.1-2.1). Among the women using other psychopharmacological medication, the incidence of postpartum haemorrhage before matching was 12.0% versus 6.1% (p = 0.08) with OR 2.1 (95% CI 0.9-4.9), and after matching 12.1% versus 4.4% (p = 0.03) with aOR of 3.3 (95% CI 1.1-9.8). CONCLUSIONS: Pregnant women using serotonergic medication have an increased risk of postpartum haemorrhage, but this high risk is also seen in pregnant women using other psychopharmacological medication. We suggest that this higher risk of postpartum haemorrhage could not only be explained by serotonin, but also by other mechanisms. An additional explanation could be the underlying psychiatric disorder.


Assuntos
Antidepressivos/efeitos adversos , Hemorragia Pós-Parto/induzido quimicamente , Hemorragia Pós-Parto/epidemiologia , Inibidores Seletivos de Recaptação de Serotonina/efeitos adversos , Adulto , Antidepressivos/administração & dosagem , Ansiedade/tratamento farmacológico , Estudos de Coortes , Depressão/tratamento farmacológico , Feminino , Humanos , Razão de Chances , Gravidez , Fatores de Risco , Inibidores Seletivos de Recaptação de Serotonina/administração & dosagem
12.
Clin Infect Dis ; 65(6): 1026-1032, 2017 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-28520858

RESUMO

Rapid diagnosis of respiratory virus infections contributes to patient care. This systematic review evaluates the diagnostic accuracy of rapid tests for the detection of respiratory viruses. We searched Medline and EMBASE for studies evaluating these tests against polymerase chain reaction as the reference standard. Of 179 studies included, 134 evaluated rapid tests for influenza viruses, 32 for respiratory syncytial virus (RSV), and 13 for other respiratory viruses. We used the bivariate random effects model for quantitative meta-analysis of the results. Most tests detected only influenza viruses or RSV. Summary sensitivity and specificity estimates of tests for influenza were 61.1% and 98.9%. For RSV, summary sensitivity was 75.3%, and specificity, 98.7%. We assessed the quality of studies using the Quality Assessment of Diagnostic Accuracy Studies (QUADAS-2) checklist. Because of incomplete reporting, the risk of bias was often unclear. Despite their intended use at the point of care, 26.3% of tests were evaluated in a laboratory setting. Although newly developed tests seem more sensitive, high-quality evaluations of these tests are lacking.


Assuntos
Diagnóstico Precoce , Influenza Humana/diagnóstico , Testes Imediatos , Infecções por Vírus Respiratório Sincicial/diagnóstico , Técnicas de Diagnóstico do Sistema Respiratório , Humanos , Reação em Cadeia da Polimerase , Doenças Respiratórias/diagnóstico , Doenças Respiratórias/virologia , Sensibilidade e Especificidade , Fatores de Tempo
13.
Fam Pract ; 34(5): 558-563, 2017 09 01.
Artigo em Inglês | MEDLINE | ID: mdl-28369370

RESUMO

Background: Inappropriately high levels of antibiotics are still prescribed in primary health care for respiratory tract infections (RTIs). Access to diagnostic point-of-care tests (POCTs) for RTIs might reduce this over-prescription. Objective: The purpose of our study was to determine the diagnostic performance and clinical feasibility of a recently developed diagnostic POCT for respiratory viruses, the mariPOC®, in a Dutch primary healthcare setting. Methods: In patients with RTI symptoms presenting to a family practice during the 2015-2016 winter season, we determined the test's sensitivity and specificity relative to polymerase chain reaction (PCR) testing performed in a laboratory. The clinical feasibility of the POCT was evaluated by interviewing general practitioners (GPs). Results: One or more respiratory viruses were detected in 54.9% of the patients (n = 204). For influenza A virus (n = 24), sensitivity of the POCT was 54.2% and specificity was 98.9%; for influenza B virus (n = 18), sensitivity was 72.2% and specificity 99.5%; and for respiratory syncytial virus (RSV) (n = 12), sensitivity was 50.0% and specificity 100%. In samples with higher viral load, sensitivity was 85.7% for influenza A, 78.6% for influenza B and 85.7% for RSV. The availability of a diagnostic test for respiratory viruses was appreciated by both patients and GPs. Conclusions: Our study shows that diagnostic POCTs for respiratory viruses might contribute to a precise and evidence-based diagnosis of RTIs and could positively influence prescription of antibiotics by GPs. However, before implementation in primary healthcare, diagnostic accuracy of the POCT needs improvement and it is impact on clinical decision making should be further assessed.


Assuntos
Sistemas Automatizados de Assistência Junto ao Leito/estatística & dados numéricos , Atenção Primária à Saúde , Infecções Respiratórias/diagnóstico , Adulto , Estudos de Viabilidade , Feminino , Humanos , Prescrição Inadequada/prevenção & controle , Vírus da Influenza A/isolamento & purificação , Vírus da Influenza B/isolamento & purificação , Influenza Humana/diagnóstico , Influenza Humana/virologia , Masculino , Países Baixos , Estudos Prospectivos , Infecções Respiratórias/virologia , Estações do Ano , Sensibilidade e Especificidade , Inquéritos e Questionários
14.
J Clin Virol ; 73: 120-126, 2015 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-26599608

RESUMO

BACKGROUND: Several studies have been published regarding the epidemiology and clinical significance of the different rhinovirus (RV) species (-A, -B and -C). However, data on RV types and the associations with clinical outcome in young children are limited. Here, we investigated the clinical, virological and epidemiological characteristics of RV infections in young children with mild or asymptomatic infection (non-hospitalised children) and in symptomatic young children admitted to the hospital. OBJECTIVES: The aim of this study was to evaluate associations between different characteristics of RV infections and clinical outcome in young children. STUDY DESIGN: RV-infected children were retrospectively selected from a Dutch birth cohort (EUROPA-study) and from hospitalised children admitted to the hospital because of respiratory symptoms. In total 120 RV-typed samples could be selected from 65 non-hospitalised and 49 hospitalised children between November 2009 and December 2012. RESULTS: RV-A was the predominant species in both study populations, followed closely by RV-C. RV-B was observed only sporadically. The distribution of the RV species was comparable in non-hospitalised and hospitalised children. In children with respiratory distress who required ICU-admission the distribution of RV species did not differ significantly from the non-hospitalised children. No predominant RV type was present in non-hospitalised nor hospitalised children. However, hospitalised children were younger, had more often an underlying illness, a higher RV load and more frequently a bacterial co-infection. CONCLUSIONS: Clinical outcome of RV infected young children was not related to RV species or types, but may more likely be influenced by multiple (host-specific) factors.


Assuntos
Infecções por Picornaviridae/diagnóstico , Infecções por Picornaviridae/epidemiologia , Infecções Respiratórias/virologia , Rhinovirus/classificação , Rhinovirus/isolamento & purificação , Criança Hospitalizada/estatística & dados numéricos , Pré-Escolar , Feminino , Humanos , Lactente , Masculino , Países Baixos/epidemiologia , Prognóstico , Estudos Retrospectivos , Carga Viral
15.
Eur J Obstet Gynecol Reprod Biol ; 189: 38-47, 2015 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-25845914

RESUMO

The use of antidepressants in pregnancy is increasing. Concerns have risen about the use of antidepressants during pregnancy and the risk of postpartum hemorrhage (PPH). The aim of this systematic review is to summarize evidence on the association between use of antidepressants during pregnancy and the risk of PPH. An Embase and Pubmed search was conducted. English and Dutch language studies reporting original data regarding bleeding after delivery associated with exposure to antidepressants during pregnancy were selected. Quality appraisal was conducted using the Newcastle Ottawa Scale (NOS). Out of 81 citations, 4 studies were included. Based on the NOS, 3 were considered of good quality and 1 was considered of satisfactory quality. Two studies reported an increased incidence of PPH in women who used antidepressants during pregnancy. The other two studies identified no overall increased risk of PPH among pregnant women exposed to antidepressants. The existing evidence remains inconclusive whether use of antidepressants during pregnancy is associated with an increased risk of postpartum hemorrhage. If there is such an association the absolute increased risk will be low and the clinical relevance needs to be further examined.


Assuntos
Antidepressivos/efeitos adversos , Hemorragia Pós-Parto/epidemiologia , Feminino , Humanos , Hemorragia Pós-Parto/induzido quimicamente , Gravidez , Fatores de Risco , Inibidores Seletivos de Recaptação de Serotonina/efeitos adversos
16.
J Clin Virol ; 65: 20-2, 2015 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-25766981

RESUMO

The incidence of coxsackievirus A6 (CV-A6) associated hand, foot and mouth disease (HFMD) has reportedly increased since 2008 with sometimes severe complications. We here describe an atypical course of CV-A6-associated HFMD in extremely low birth weight twins. The CV-A6-strains are genetically closely related to international strains isolated from HFMD outbreaks.


Assuntos
Doenças em Gêmeos/diagnóstico , Enterovirus/isolamento & purificação , Doença de Mão, Pé e Boca/diagnóstico , Recém-Nascido de Peso Extremamente Baixo ao Nascer , Recém-Nascido de Baixo Peso , Doenças do Prematuro/diagnóstico , Doenças em Gêmeos/virologia , Enterovirus/classificação , Feminino , Doença de Mão, Pé e Boca/virologia , Humanos , Recém-Nascido , Recém-Nascido Prematuro , Doenças do Prematuro/virologia , Masculino , Filogenia , Fatores de Risco , Gêmeos
17.
Diagn Microbiol Infect Dis ; 80(4): 292-3, 2014 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-25241640
18.
Physiol Biochem Zool ; 86(5): 538-46, 2013.
Artigo em Inglês | MEDLINE | ID: mdl-23995484

RESUMO

Life-history evolution-the way organisms allocate time and energy to reproduction, survival, and growth-is a central question in evolutionary biology. One of its main tenets, the allocation principle, predicts that selection will reduce energy costs of maintenance in order to divert energy to survival and reproduction. The empirical support for this principle is the existence of a negative relationship between fitness and metabolic rate, which has been observed in some ectotherms. In juvenile animals, a key function affecting fitness is growth rate, since fast growers will reproduce sooner and maximize survival. In principle, design constraints dictate that growth rate cannot be reduced without affecting maintenance costs. Hence, it is predicted that juveniles will show a positive relationship between fitness (growth rate) and metabolic rate, contrarily to what has been observed in adults. Here we explored this problem using land snails (Cornu aspersum). We estimated the additive genetic variance-covariance matrix for growth and standard metabolic rate (SMR; rate of CO2 production) using 34 half-sibling families. We measured eggs, hatchlings, and juveniles in 208 offspring that were isolated right after egg laying (i.e., minimizing maternal and common environmental variance). Surprisingly, our results showed that additive genetic effects (narrow-sense heritabilities, h(2)) and additive genetic correlations (rG) were small and nonsignificant. However, the nonadditive proportion of phenotypic variances and correlations (rC) were unexpectedly large and significant. In fact, nonadditive genetic effects were positive for growth rate and SMR ([Formula: see text]; [Formula: see text]), supporting the idea that fitness (growth rate) cannot be maximized without incurring maintenance costs. Large nonadditive genetic variances could result as a consequence of selection eroding the additive genetic component, which suggests that past selection could have produced nonadditive genetic correlation. It is predicted that this correlation is reduced when adulthood is attained and selection starts to promote the reduction in metabolic rate.


Assuntos
Metabolismo Energético/genética , Metabolismo Energético/fisiologia , Aptidão Genética/fisiologia , Caramujos/crescimento & desenvolvimento , Caramujos/metabolismo , Animais , Regulação da Expressão Gênica , Aptidão Genética/genética , Variação Genética , Óvulo/fisiologia , Caramujos/genética , Água/metabolismo
19.
Artigo em Inglês | MEDLINE | ID: mdl-23474253

RESUMO

The strong dependence of metabolic rates on body mass has attracted the interest of ecological physiologists, as it has important implications to many aspects of biology including species variations in body size, the evolution of life history, and the structure and function of biological communities. The great diversity of observed scaling exponents has led some authors to conclude that there is no single universal scaling exponent, but instead it ranges from 2/3 to 1. Most of the telling evidence against the universality of power scaling exponents comes from ontogenetic changes. Nevertheless, there could be other sources of phenotypic variation that influence this allometric relationship at least at the intraspecific level. In order to explore the general concept of the metabolic scaling in terrestrial molluscs we tested the role of several biological and methodological sources of variation on the empirically estimated scaling exponent. Specifically, we measured a proxy of metabolic rate (CO(2) production) in 421 individuals, during three generations, in three different populations. Additionally, we measured this scaling relationship in 208 individuals at five developmental stages. Our results suggest that the metabolic scaling exponent at the intraspecific level does not have a single stationary value, but instead it shows some degree of variation across geographic distribution, transgenerational change and ontogenetic stages. The major differences in the metabolic scaling exponent that we found were at different developmental stages of snails, because ontogeny involves increases in size at different rates, which in turn, generate differential energy demands.


Assuntos
Ecossistema , Metabolismo Energético , Caracois Helix/metabolismo , Caracois Helix/fisiologia , Animais , Tamanho Corporal/fisiologia , Dióxido de Carbono/metabolismo , Chile , Geografia , Caracois Helix/classificação , Modelos Biológicos , Consumo de Oxigênio/fisiologia , Especificidade da Espécie
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