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AIM: Perforated appendicitis has poorer clinical outcomes compared to non-perforated appendicitis. However, accurate outcome comparisons in research and clinical audits are challenged by its wide spectrum of manifestation. Previous attempts at the classification of severity have been complex and difficult to reproduce. In our study, we used another institution's (Jones et al., TX, USA) previously described simple classification system of peritoneal contamination and examined its usefulness in predicting outcomes. METHODS: With ethical approval, we retrospectively reviewed the records of all paediatric patients operated at our institution for perforated appendicitis from 2016 to 2017. Patient demographics, intra-operative and histological findings, post-operative outcomes and length of stay were collected. Patients were categorised into group 1 (purulence in right lower quadrant only) and group 2 (contamination in two or more quadrants). Post-operative complications were defined as procedure-related (e.g. post-operative ileus, intra-abdominal abscess, visceral injury) and non-procedure-related (e.g. bronchospasm). Statistical analysis using χ2 tests for categorical data and Mann-Whitney U-tests for non-parametric continuous variables was performed, with a significance of P < 0.05. RESULTS: There were 134 eligible patients. We excluded 19 with incomplete data, leaving 115 for analysis, of which 69 (60%) were in group 2. Those in group 2 had a longer stay (P = 0.005) and more post-operative complications (P = 0.001), particularly procedure-related events (P = 0.006). There were no differences in age (P = 0.182), gender (P = 0.876), readmission rate (P = 0.317) and non-procedure-related post-operative complications (0.152). CONCLUSION: This simple classification of perforated appendicitis appears to differentiate clinical outcomes well, particularly for iatrogenic morbidity, making it useful for operative preparation and outcomes research.
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Abscesso Abdominal , Apendicite , Apendicectomia/efeitos adversos , Apendicite/cirurgia , Criança , Humanos , Tempo de Internação , Complicações Pós-Operatórias/epidemiologia , Complicações Pós-Operatórias/etiologia , Estudos RetrospectivosRESUMO
BACKGROUND: Bullying victimization in childhood is associated with a broad array of serious mental health disturbances, including anxiety, depression, and suicidal ideation and behavior. The key goal of this study was to evaluate whether bullying victimization is a true environmental risk factor for psychiatric disturbance using data from 145 bully-discordant monozygotic (MZ) juvenile twin pairs from the Virginia Twin Study of Adolescent Behavioral Development (VTSABD) and their follow-up into young adulthood. METHOD: Since MZ twins share an identical genotype and familial environment, a higher rate of psychiatric disturbance in a bullied MZ twin compared to their non-bullied MZ co-twin would be evidence of an environmental impact of bullying victimization. Environmental correlations between being bullied and the different psychiatric traits were estimated by fitting structural equation models to the full sample of MZ and DZ twins (N = 2824). Environmental associations were further explored using the longitudinal data on the bullying-discordant MZ twins. RESULTS: Being bullied was associated with a wide range of psychiatric disorders in both children and young adults. The analysis of data on the MZ-discordant twins supports a genuine environmental impact of bullying victimization on childhood social anxiety [odds ratio (OR) 1.7], separation anxiety (OR 1.9), and young adult suicidal ideation (OR 1.3). There was a shared genetic influence on social anxiety and bullying victimization, consistent with social anxiety being both an antecedent and consequence of being bullied. CONCLUSION: Bullying victimization in childhood is a significant environmental trauma and should be included in any mental health assessment of children and young adults.
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Ansiedade de Separação/epidemiologia , Bullying/estatística & dados numéricos , Vítimas de Crime/estatística & dados numéricos , Fobia Social/epidemiologia , Ideação Suicida , Adolescente , Adulto , Ansiedade de Separação/etiologia , Criança , Doenças em Gêmeos/epidemiologia , Feminino , Humanos , Estudos Longitudinais , Masculino , Fobia Social/etiologia , Gêmeos Monozigóticos , Adulto JovemRESUMO
BACKGROUND: Smith-Magenis syndrome (SMS) is a neurodevelopmental disorder that affects approximately one out of 25,000 births worldwide. To date, no research has been conducted to investigate how having an individual with SMS in a family is a positive or negative influence on siblings. METHODS: To investigate this question we conducted a study involving 79 siblings and 60 parents of individuals with SMS to assess perceptions of how having a sibling with SMS positively and negative influence siblings' behavioural traits. RESULTS: Our findings show that age of siblings of individuals with SMS was associated with a significant increase in positive behavioural traits and a significant decrease in negative behavioural traits. Additionally, siblings who perceive benefits from having a sibling with SMS demonstrate significantly more positive behavioural traits and significantly fewer negative behavioural traits. Parents accurately assess the changes in sibling behavioural traits with age, and parents who perceive their child as having experienced benefits from the sibling relationship report that siblings demonstrate significantly more positive behavioural traits and significantly fewer negative behavioural traits. CONCLUSIONS: Our research shows that although individuals experience difficulties as a result of having a sibling with SMS, overall, siblings tend to fare well and parents appreciate both the positive and negative behavioural effects that result from having a sibling with SMS.
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Transtornos Mentais/etiologia , Transtornos Mentais/psicologia , Relações entre Irmãos , Irmãos/psicologia , Síndrome de Smith-Magenis/complicações , Síndrome de Smith-Magenis/psicologia , Adaptação Psicológica , Adolescente , Adulto , Atitude Frente a Saúde , Criança , Pré-Escolar , Estudos Transversais , Feminino , Humanos , Masculino , Pais/psicologia , Adulto JovemRESUMO
The objective of this study was to describe the clinical features of cases hospitalized with West Nile virus (WNV) infections and identify clinical parameters that could potentially predict poor outcome (death). Retrospective medical chart reviews were completed for 172 confirmed cases of WNV infection hospitalized in the Houston, Texas, metropolitan area between 2002 and 2004. Of the 172 patients, 113 had encephalitis which resulted in 17 deaths, 47 had meningitis, and 12 had uncomplicated fever. Risk factors associated with progression from encephalitis to death were absence of pleocytosis in the cerebrospinal fluid, renal insufficiency, requiring intubation and mechanical ventilation, presence of myoclonus or tremors, and loss of consciousness. These findings can aid physicians in evaluating their patients suspected of WNV infection and determining outcomes in their patients with confirmed WNV neuroinvasive disease.
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Hospitalização , Febre do Nilo Ocidental/patologia , Aciclovir/uso terapêutico , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Antibacterianos/uso terapêutico , Antivirais/uso terapêutico , Criança , Pré-Escolar , Feminino , Humanos , Lactente , Masculino , Pessoa de Meia-Idade , Estudos Retrospectivos , Fatores de Risco , Texas/epidemiologia , Febre do Nilo Ocidental/tratamento farmacológico , Febre do Nilo Ocidental/epidemiologia , Febre do Nilo Ocidental/mortalidadeRESUMO
In broilers, 2-hydroxy-4(methylthio) butanoic acid (HMTBA) can elicit a different dose response relative to dl-Met (DLM) such that birds could have lower gain responses at deficient TSAA concentrations but greater gain responses at maximum response concentrations. Two experiments tested if the 2 Met sources have a different dose response in 1-d-old turkeys using a 2 x 4 factorial plus a control design with 8 replicates of 12 toms per treatment. 2-Hydroxy-4(methylthio) butanoic acid and DLM were supplemented at equimolar concentrations of 0.05, 0.10, 0.15, and 0.20% or 0.04, 0.08, 0.16, and 0.32% for experiments 1 and 2, respectively, in commercial-type TSAA-deficient (0.99 to 1.02%) diets for 21 d. No differences in any performance parameter tested were found between HMTBA and DLM in either trial by ANOVA. Linear (LIN), quadratic (QUAD), and exponential regressions were fitted to the gain response of birds fed HMTBA or DLM. Equations with better goodness of fit as determined by Schwarz's Bayesian information criteria index were used for further calculations of predicted differences between HMTBA and DLM. In both trials, the shape of the dose response differed according to the Met source used, and best-fit equations were obtained when using Met intake over control rather than dietary Met concentration as the dependent variable. In experiment 1, the best-fit equations were an inverse QUAD for HMTBA and a LIN for DLM, and in experiment 2 with higher Met concentrations, the best-fit equations were a QUAD for DLM and a LIN for HMTBA. Feeding HMTBA at deficient TSAA resulted in lower (P <0.05) gains in experiment 1 but greater gains at maximum response concentrations (P <0.05) in both experiments. Plasma-free Met increased at 3 times the rate for DLM than HMTBA (P <0.01) with increasing Met concentration, which may play a role in the evolution of different dose responses at the extremes of the Met dose response. These results demonstrate that Met sources elicit a differential dose response in turkeys such that feeding HMTBA at deficient TSAA concentrations can be lower than DLM and can reach a higher maximum performance than with DLM.
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Metionina/análogos & derivados , Metionina/farmacologia , Perus/crescimento & desenvolvimento , Aumento de Peso/efeitos dos fármacos , Ração Animal , Fenômenos Fisiológicos da Nutrição Animal , Animais , Dieta/veterinária , Suplementos Nutricionais , Relação Dose-Resposta a Droga , MasculinoRESUMO
Superior mesenteric artery (SMA) syndrome is a rare but potentially fatal complication following spinal fusion for scoliosis. The aims of our study were to identify clinical features and evaluate their importance in SMA syndrome following posterior spinal fusion (PSF) in adolescent idiopathic scoliosis (AIS) patients and to recommend a simple approach for the recognition and management of SMA syndrome. This is an IRB-approved study. Three patients in our series and 11 patients from other published case reports who underwent PSF for adolescent idiopathic scoliosis were included in our study. Patient demographics, clinical presentation, investigations, and management were recorded and analyzed. In this combined series of 14 patients (mean age 14.8 years), the main presenting clinical features included vomiting of any kind (92.9%), abdominal pain/tenderness (57.1%), abdominal distension (42.9%), bilious vomiting (35.7%), and hypoactive bowel sounds (28.6%). Most patients presented within 2 weeks of surgery (71.4%). In total, 50% of patients presented with both vomiting (of any kind) and abdominal tenderness. The number of presenting symptoms appeared to be directly related to the severity of SMA syndrome. Our second patient had intermittent vomiting on postoperative day (POD) 3, which was initially considered as insignificant; she was discharged on POD 9 and readmitted for recurrent vomiting, during which SMA syndrome was diagnosed. Our first patient presented in the classical manner. Our third patient had bilious vomiting after discharge that started on POD 13 and increased in frequency until readmission on POD 27. Vomiting and abdominal pain are nonspecific symptoms following PSF; differentiating between SMA syndrome and postoperative ileus can be challenging. The highest index of suspicion applies to patients who present within the first week with symptoms of vomiting and abdominal pain. We propose an algorithm for the management of SMA syndrome, which includes a focused clinical assessment to evaluate for intestinal obstruction, followed by an abdominal radiography and barium contrast study if clinical assessment is positive. An early referral to general surgery should be considered especially for high-risk patients (BMI<5% percentile, sagittal kyphosis). Early diagnosis of SMA syndrome allows for early intervention, reducing the likelihood of future complications and need for surgery.
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Escoliose/cirurgia , Fusão Vertebral/efeitos adversos , Síndrome da Artéria Mesentérica Superior/etiologia , Adolescente , Algoritmos , Estudos de Coortes , Árvores de Decisões , Feminino , Humanos , Masculino , Síndrome da Artéria Mesentérica Superior/diagnóstico , Síndrome da Artéria Mesentérica Superior/terapiaRESUMO
ETHNOPHARMACOLOGICAL RELEVANCE: Abundant availability of medicinal plants in the study area offers low cost health care, but scientific validation is needed in order to lend credibility to the traditional use against respiratory infections. AIM OF THE STUDY: This study focussed on determining the antimicrobial efficacies of 30 plant species (independently and in various combinations) used for respiratory related infections in rural Maputaland. MATERIALS AND METHODS: In vitro minimum inhibitory concentration (MIC) assays were undertaken on dichloromethane-methanol (CH(2)Cl(2): MeOH) and aqueous extracts, as well as the hydro-distilled essential oils (for aromatic plants). Selected plant parts were assessed for antimicrobial activity against a range of respiratory pathogens i.e. Cryptococcus neoformans (ATCC 14116), Klebsiella pneumoniae (ATCC 13883), Moraxella catarrhalis (ATCC 23246), Mycobacterium smegmatis (ATCC 14468) and Staphylococcus aureus (ATCC 6538). The sum of the fractional inhibitory concentrations (∑FIC) was determined for plants traditionally used in combination. Isobolograms represent MIC values for a selection of interactions where two plants were combined in various ratios. RESULTS: The most antimicrobially active aqueous extracts were that of Ozoroa obovata and Sclerocarya birrea (0.10 mg/ml) while organic extracts from Parinari capensis subsp. incohata and Tetradenia riparia demonstrated the most noteworthy (0.03 mg/ml) activity. Although both Lippia javanica and Eucalyptus grandis were by far the most popular plants traditionally used for respiratory infections, the antimicrobial activity was mostly only moderate. Furthermore, the traditional use in a 1:1 combination did not display strong antimicrobial interactions, but isobolograms demonstrate (against some test organisms) that when combined in various ratios, predominant additive interactions are evident where E. grandis was present in larger proportions. The combination of E. grandis with O. obovata demonstrated synergism against both C. neoformans and K. pneumoniae, with ∑FIC values of 0.34 and 0.28 respectively. Various ratios of these two plants also demonstrated a predominantly synergistic profile. CONCLUSION: Although this in vitro study supports the traditional use of some plants independently and in combination for the treatment of respiratory ailments in rural Maputaland, results demonstrate that the traditional selection of plants in higher frequency do not necessarily correlate with higher antimicrobial efficacy.
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Anti-Infecciosos/farmacologia , Medicinas Tradicionais Africanas , Extratos Vegetais/farmacologia , Bactérias/efeitos dos fármacos , Cryptococcus neoformans/efeitos dos fármacos , Testes de Sensibilidade Microbiana , Plantas Medicinais , Infecções Respiratórias/tratamento farmacológico , População Rural , África do SulRESUMO
ETHNOPHARMACOLOGICAL RELEVANCE: Traditional remedies are frequently used in treating various respiratory ailments, and are very important in the primary health care of the people living in rural Maputaland, KwaZulu-Natal, South Africa. Novel information gathered from surveys like the present study is important in preserving indigenous knowledge. AIM OF THE STUDY: To explore the knowledge that the lay people of a rural community in northern Maputaland have about medicinal plants used in the vicinity to treat respiratory infections. MATERIALS AND METHODS: Interviews were conducted among 80 homestead inhabitants, using structured questionnaires where convenience sampling was used. The focus was on plants used in treating respiratory infections. Some of the main topics discussed during the interviews were vernacular plant names, plant parts used, harvested amounts, preparation methods, dosage forms and quantities, use of plants in combination as well as the related symptomatic relief associated with respiratory infections. RESULTS: The study documented 30 plant species (18 families) which are used to treat respiratory infections by the rural people in the study area. Decoctions made with these plants are mostly taken orally, combined with the use of steaming. To the best of our knowledge, Acanthospermum glabratum, Aloe marlothii, Krauseola mosambicina, Ozoroa obovata, Parinari capensis and Plectranthus neochilus are recorded for the first time globally as medicinal plants used for treating respiratory infections and related symptoms. The indigenous aromatic shrub, Lippia javanica was by far the most frequently used plant species, followed by Eucalyptus grandis (an exotic), Tetradenia riparia and then Senecio serratulloides. Twenty-four different plant combinations were used where the most frequently used combination encountered was Eucalyptus grandis with Lippia javanica. CONCLUSION: The large number of different plant species traditionally used against respiratory infections supports previous research on the importance of traditional medicine in the primary health care of this remote area. The finding of new vernacular plant names and plant uses in the current survey shows the importance of the documentation of such ethnobotanical knowledge.
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Etnobotânica , Medicina Tradicional , Fitoterapia , Extratos Vegetais/uso terapêutico , Plantas Medicinais , Infecções Respiratórias/tratamento farmacológico , Coleta de Dados , Humanos , Entrevistas como Assunto , População Rural , África do Sul , Inquéritos e QuestionáriosRESUMO
We conducted a nested case-control study to determine potential risk factors for developing encephalitis from West Nile virus (WNV) infection. Retrospective medical chart reviews were completed for 172 confirmed WNV cases hospitalized in Houston between 2002 and 2004. Of these cases, 113 had encephalitis, including 17 deaths, 47 had meningitis, and 12 were fever cases; 67% were male. Homeless patients were more likely to be hospitalized from WNV compared to the general population. A multiple logistic regression model identified age [odds ratio (OR) 1.1, P<0.001], history of hypertension, including those cases taking hypertension-inducing drugs (OR 2.9, P=0.012), and history of cardiovascular disease (OR 3.5, P=0.061) as independent risk factors for developing encephalitis from WNV infection. After adjusting for age, race/ethnicity (being black) (OR 12.0, P<0.001), chronic renal disease (OR 10.6, P<0.001), hepatitis C virus (OR 23.1, P=0.0013), and immunosuppression (OR 3.9, P=0.033) were identified as risk factors for death from WNV infection.
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Encefalite/etiologia , Febre do Nilo Ocidental/epidemiologia , Adolescente , Adulto , Idoso , Estudos de Casos e Controles , Criança , Pré-Escolar , Encefalite/epidemiologia , Encefalite/mortalidade , Feminino , Pessoas Mal Alojadas , Humanos , Masculino , Pessoa de Meia-Idade , Estudos Retrospectivos , Fatores de Risco , Febre do Nilo Ocidental/complicações , Febre do Nilo Ocidental/imunologia , Febre do Nilo Ocidental/mortalidadeRESUMO
A newly developed modern analytic approach, Multivariate Adaptive Regression Splines (MARS), was used to identify both genetic and non-genetic factors involved in the etiology of a common disease. We tested this method on the simulated data provided by the Genetic Analysis Workshop (GAW) 12 in problem 2 for the isolated population. MARS simultaneously analyzes all inputs, in this case DNA sequence variants and non-genetic data, and selectively prunes away variables contributing insignificantly to fit by internal cross-validation to arrive at a generalizable predictive model of the response. The relevant factors identified, by means of an importance value computed by MARS, were assumed to be associated with risk to the disease. The application of a series of subsequent models identified the quantitative traits and a single major gene contributing directly to risk liability using five sets of 7,000 individuals.
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Predisposição Genética para Doença/genética , Modelos Genéticos , Genética Populacional , Humanos , Característica Quantitativa Herdável , Análise de RegressãoRESUMO
With the presumption that a shifted Maxwellian velocity distribution adequately describes the electrons in a flowing plasma, a method with optimum signal to noise resolution to measure directed velocity is described. The lowest velocity that can be determined by this method is shown to depend on the electron random thermal velocity. The basic diagnostic system is outlined and consists of a ruby laser source and two detectors set 180 degrees from each other and both set at 90 degrees with respect to the incident laser beam. Simplified analysis compared to standard peak shift detection techniques is seen to be possible using optimization techniques. This proposed method is shown to be superior in SNR for plasma temperature below 7.2 eV.
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Iliac compression syndrome is usually diagnosed during the third and fourth decades of life when the patient has iliofemoral deep vein thrombosis. Catheter-directed thrombolytic therapy is an accepted method of treatment for iliofemoral deep vein thrombosis, which has been reported to afford greater success with clot dissolution than with system therapy. Although this method is not new, this is the first case, to our knowledge, reporting successful treatment of computerized tomographically demonstrated iliac compression syndrome with stent placement after lysis and insufficient response to balloon angioplasty.
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Veia Ilíaca/cirurgia , Stents , Trombose/cirurgia , Constrição Patológica/cirurgia , Humanos , Masculino , Pessoa de Meia-Idade , SíndromeRESUMO
Conventional Thomson scattering using a ruby laser evidences difficulty in scattered signal detection for electron densities < 10(13) cm(-3). Use of a Nd-glass laser source in combination with appropriate detectors can result in gains in the resolution of scattered signal of at least 1 order of magnitude over a conventional ruby laser system. However, due to the ~2.5-nm full bandwidth of a Nd-glass laser line, the electron temperature information in the incoherent scattered signal must be extracted from a Voigt profile, not from the usual Gaussian profile as when a ruby laser is used.
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Approximately 20% of B-lineage acute lymphoblastic leukemias are not cured by traditional chemotherapy. The possibility was examined that residual leukemic cells that potentially contribute to relapse are harbored in association with fibroblastic stromal cells in the bone marrow. Modulation of cytarabine (Ara-C) and etoposide (VP-16) efficacy by bone marrow stromal cells in vitro was investigated. Stromal cell coculture was shown to sustain the proliferation of B-lineage leukemic cells and to reduce leukemic cell apoptosis when exposed to Ara-C or VP-16. Direct contact with stromal cells was essential for the protection of leukemic cells during chemotherapy, whereas soluble factors had negligible effect. Specifically, signaling mediated through interaction with the stromal cell adhesion molecule VCAM-1 was required to maintain the maximum viability of leukemic cells during Ara-C and VP-16 exposure. In contrast, the interaction of leukemic cells with fibronectin did not confer significant resistance to either chemotherapeutic agent. These observations suggest a role for the bone marrow microenvironment in modulating the response of B-lineage leukemic cells to Ara-C or VP-16, and they indicate specific molecular interactions that may be important in determining the sensitivity of leukemic cells to treatment. (Blood. 2000;96:1926-1932)
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Células da Medula Óssea/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Leucemia de Células B/tratamento farmacológico , Células Estromais/efeitos dos fármacos , Antineoplásicos/farmacologia , Apoptose/efeitos dos fármacos , Células da Medula Óssea/citologia , Ciclo Celular/efeitos dos fármacos , Morte Celular/efeitos dos fármacos , Técnicas de Cocultura , Meios de Cultivo Condicionados/química , Meios de Cultivo Condicionados/farmacologia , Citarabina/farmacologia , Etoposídeo/farmacologia , Fibronectinas/metabolismo , Humanos , Células Jurkat , Cinética , Leucemia de Células B/patologia , Proteínas de Membrana/metabolismo , Ligação Proteica , Transdução de Sinais , Células Estromais/citologia , Fatores de Tempo , Células Tumorais Cultivadas , Molécula 1 de Adesão de Célula Vascular/metabolismoRESUMO
PURPOSE: To determine whether retrograde passage of a coaxial infusion system (Mewissen-Katzen catheter and guide wire) into extremity veins with valves causes damage. MATERIALS AND METHODS: Retrograde common femoral vein puncture and passage of an infusion wire-catheter system through the superficial femoral and popliteal veins of one leg were performed in five anesthetized pigs. Heparinized saline was then infused via the catheter and wire for approximately 8 hours. The pigs were then killed, and the femoropopliteal veins were removed from both legs of each pig and examined by a pathologist. The noncatheterized leg veins served as a control in each animal. RESULTS: Valvular damage occurred in one of five pigs. This may have resulted from leg movement during catheter passage in this animal. CONCLUSION: Retrograde passage of a catheter-guide-wire infusion system caused minimal to no damage to the venous valves of pigs. This suggests that human venous valves may be spared injury during catheter-directed venous thrombolysis. Further study of catheter manipulation in a model of deep venous thrombosis is needed.
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Cateterismo Periférico/instrumentação , Veia Femoral/patologia , Veia Poplítea/patologia , Animais , Anticoagulantes/administração & dosagem , Cateterismo Periférico/efeitos adversos , Modelos Animais de Doenças , Endotélio Vascular/lesões , Endotélio Vascular/patologia , Veia Femoral/lesões , Hemorragia/etiologia , Hemorragia/patologia , Heparina/administração & dosagem , Membro Posterior/irrigação sanguínea , Humanos , Infusões Intravenosas/efeitos adversos , Infusões Intravenosas/instrumentação , Veia Poplítea/lesões , Cloreto de Sódio/administração & dosagem , Suínos , Terapia Trombolítica/instrumentação , Tromboflebite/tratamento farmacológicoRESUMO
BACKGROUND: Fatigue is a complex symptom associated with many physiological, psychological and pathological processes. Its correlates and typology remain inadequately understood. METHOD: These data were from two large, longitudinal twin studies. Trained interviewers enquired as to the presence of a > or = 5 day period in the previous year of fatigue or tiredness that interfered with daily activities. A range of potential correlates was assessed in a structured interview: demography; health beliefs; the presence of nine physical disorders; mood, anxiety and addictive disorders; neuroticism and extraversion; recollections of parental rearing; and nine stressful life events. Statistical analyses included logistic regression, CART, MARS, latent class analysis and univariate twin modelling. RESULTS: Data were available for interfering fatigue (IF) on 7740 individual twins (prevalence 9.9% in the previous year). IF was significantly associated with 42 of 52 correlates (most strongly with major depression, generalized anxiety disorder, reported major health problems and neuroticism). Multivariate analyses demonstrated that IF is a highly complex construct with different sets of correlates in its subtypes. There were two broad clusters of correlates of IF: (a) major depression, generalized anxiety disorder and neuroticism; and (b) beliefs of ill health coexisting with alcoholism and stressful life events. Twin analyses were consistent with aetiological heterogeneity--genetic effects may be particularly important in women and shared environmental effects in men. CONCLUSIONS: IF is a complex and common human symptom that is highly heterogeneous. More precise understanding of the determinants of IF may lead to a fuller understanding of more extreme conditions like chronic fatigue syndrome.