A prototype sensor array was developed for use with laboratory automation to permit closed-loop control of liquid-levels in a multiwell microplate geometry. A simple electrical model for non-contact capacitance-based fluid sensors was extended to describe a fluid-level dependency. The new model shows that a charge-transfer based capacitance transducer employing a liquid-specific calibration can be used to obtain an output signal that varies linearly with the liquid-level when fringe-field effects are negligible. The calibration also compensates for liquid-to-liquid conductivity and permittivity differences. / The sensor was tested using sodium chloride (NaCl) and ethanol solutions to simulate the range of conductivity and permittivity typical in biological and chemical research. Measured capacitance was a second-order function of liquid volume due to fringe-field effects and was compensated for by adding a hardware-based calibration. Liquid-volume measurement error averaged 0.2% of the 120mul fill volume with a standard deviation of 0.6% (< mul). The maximum absolute error for all liquids was 2.7% (3mul).

Dissertation (Ph.D.)--University of South Florida, 2006. / Title from PDF of title page. Document formatted into pages; contains 122 pages. Includes vita. Includes bibliographical references.

Made available in DSpace on 2014-06-11T19:27:18Z (GMT). No. of bitstreams: 0 Previous issue date: 2006-04-24Bitstream added on 2014-06-13T20:16:25Z : No. of bitstreams: 1 taparo_cv_me_araca.pdf: 677501 bytes, checksum: cb871034a8580ee800d34d6d183f9ac3 (MD5) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / As enteroparasitoses comumente afetam o equilíbrio orgânico dos animais de estimação, sendo isto particularmente preocupante em relação aos cães, devido ao intimo contato destes com o homem. As técnicas coproparasitológicas usualmente utilizadas na rotina laboratorial para detecção de parasitoses gastrintestinais são indispensáveis para o diagnóstico e por conseqüência para determinar a necessidade de tratamento dos animais infectados. Neste estudo objetivou-se avaliar a ocorrência de helmintoses e protozooses em cães domiciliados e sua associação com faixa etária, sexo e raça, bem como a eficiência dos Métodos Willis- Mollay, Faust, Sedimentação e Exame Direto quanto a recuperação de ovos e oocistos de parasitos gastrintestinais da espécie canina. Foram processadas 401 amostras fecais, sendo que em 300 foi efetuada a Técnica de Kinyoun para pesquisa de Cryptosporidium spp. Os parasitos encontrados foram Ancylostoma spp. em 53,1%, Toxocara canis em 20,7%, Cystoisospora ohioensis em 15,7%, Trichuris vulpis em 3,7%, Dipylidium caninum em 2,5%, Cryptosporidium spp. em 1,33% e Taenia spp. em 1,0% das amostras. A positividade para Ancylostoma spp. não foi influenciada pelas variáveis raça, sexo e idade. Houve diferença estatisticamente significativa para T. canis e C. ohioensis nos cães com até seis meses de idade quando comparados a animais acima de seis meses (P<0,0001). Quanto a variável sexo houve associação apenas com o ascarídeo T. canis com maior ocorrência nos machos quando comparado as fêmeas (P = 0,0243). A associação da presença das formas evolutivas dos parasitos com raça dos cães não foi estatisticamente significativa. / The enteroparasitoses generally affect the organic equilibrium of pets, being particularly worrying referring to dogs, due to intimate contact with the human being. The techniques coproparasitologics usually used in laboratorial routines for detection of gastroenteric parasitoses are indispensable for the diagnosis and consequence to determine the necessary of infected animals treatment. In this study we evaluated the occurrence of helminthoses and protozooses in dogs and its association with age, sex and race, as well as the efficiency of Willis-Mollay, Faust, Sedimentation and exam Direct methods. It was processed 401 fecal samples, being accomplished in 300 parts, the technique of Kinyoun for directed research of Cryptosporidium spp. The parasite found were Ancylostoma spp. (53.1%), Toxocara canis (20.7%), Cystoisospora ohioensis (15.7%), Trichuris vulpis (3.7%), Dipylidium caninum (2.5%), Cryptosporidium spp. (1.33%) and Taenia spp. (1.0%). There was a statistically significant difference for T. canis and C. ohioensis in dogs up to six months old (P<0,0001). The occurrence of T. canis was statistically bigger in males when compared to females (P=0,0243). The association of parasites with race was not statistically significant. Of the four dogs (1.33%) positives for Cryptosporidium spp., only one presented a semi liquid consistence faeces and light dehydration (5 to 7%), having this animal age superior to six months old, with simultaneous infection for Ancylostoma spp. The Willis-Mollay was more efficient in the diagnosis of Ancylostoma spp. and T. canis eggs. The Direct method was least efficient. The techniques were statistically the same as the occurrence of the C. ohioensis oocysts.

Made available in DSpace on 2014-06-11T19:27:18Z (GMT). No. of bitstreams: 0 Previous issue date: 2008-09-26Bitstream added on 2014-06-13T19:35:14Z : No. of bitstreams: 1 goncales_jf_me_araca.pdf: 909821 bytes, checksum: 33d206de9703467c4c16ac6545d7052e (MD5) / O diagnóstico laboratorial da raiva em morcegos é realizado utilizando-se, principalmente, o encéfalo do animal suspeito. O objetivo do presente trabalho foi testar a hipótese de que o método de aspiração com pipeta plástica (tipo Pasteur) é eficaz na obtenção de encéfalo de morcegos para a realização do diagnóstico comparado com o método tradicional de abertura de crânio. Para tanto, estudaram-se quatro espécies diferentes de morcegos, Molossus rufus (E. Geoffroy, 1805), Molossus molossus (Pallas, 1766), Artibeus lituratus (Olfers,1818) e Myotis nigricans (Schinz, 1821), totalizando 200 amostras. A quantidade de massa encefálica obtida pelo método tradicional foi significativamente maior, contudo, o material colhido pela aspiração foi suficiente para a execução do diagnóstico da doença. Ambos os métodos detectaram indivíduos positivos, sendo que o método de aspiração teve a vantagem de preservar o crânio possibilitando melhor identificação das espécies. / Rabies diagnosis in bats is usually performed using the brain of suspected animals. The main hypothesis tested by this work was that aspiration method using plastic pipette (Pasteur type) was effective in the collection of bat brain sample for rabies diagnosis when compared to the opening skull method. A total of two hundred bats of four species were studied: Molossus rufus (E. Geoffroy, 1805), Molossus molossus (Pallas, 1766), Artibeus lituratus (Olfers, 1818) and Myotis nigricans (Schinz, 1821). The proportion of brain weight compared to body weight was statistically higher when using the traditional method, although the brain mass collected by aspiration method was enough for rabies diagnosis. Results demonstrate that independently of the collecting method, both gated to detect positive samples and the aspiration method has the advantage of skull preservation, permitting the identification of the species.

CoordenaÃÃo de AperfeiÃoamento de Pessoal de NÃvel Superior / Este trabalho teve como objetivo incentivar a implantaÃÃo de tÃcnicas de gerenciamento e procedimentos de boas prÃticas de laboratÃrio junto a Rede Brasileira de LaboratÃrios - REBLAS a partir da avaliaÃÃo de diagnÃstico situacional, a qual foi realizada atravÃs da aplicaÃÃo de questionÃrios em laboratÃrios de instituiÃÃes pÃblicas de ensino superior e pesquisa na Ãrea da saÃde em quatro capitais brasileiras. Metodologia: A pesquisa de campo foi realizada atravÃs de visitas em laboratÃrios de instituiÃÃes de ensino superior e pesquisa para diagnosticar a situaÃÃo dos mesmos por meio de entrevistas com aplicaÃÃo de questionÃrios. O tamanho da amostra foi estabelecido em cinqÃenta (50) pesquisadores, distribuÃdos em instituiÃÃes de ensino e pesquisa de quatro (04) capitais brasileiras. Em cada instituiÃÃo foram selecionados laboratÃrios e identificados os pesquisadores responsÃveis para serem entrevistados. Em seguida foi elaborado um diagnÃstico situacional dos laboratÃrios atravÃs dos quais foram comparados modelos de boas prÃticas de laboratÃrio previamente existentes na literatura com aqueles dos laboratÃrios entrevistados, os quais foram avaliados e conduzidos sob sigilo absoluto, de modo a manter a integridade dos laboratÃrios e instituiÃÃes em questÃo. Resultados: atravÃs do diagnÃstico situacional dos laboratÃrios foram desenvolvidos modelos de procedimentos de boas prÃticas de laboratÃrio e garantia da qualidade (procedimentos operacionais padrÃo e formulÃrios), os quais poderÃo ser implantados e implementados em laboratÃrios de instituiÃÃes pÃblicas de ensino superior e pesquisa existente no Brasil. ConclusÃo: As concepÃÃes teÃricas que fundamentaram a dissertaÃÃo foram analisadas e comparadas com as pesquisas teÃricas e de campo e viabilizaram a escolha e elaboraÃÃo de tÃcnicas de gerenciamento e procedimentos padronizados em funÃÃo do diagnÃstico situacional dos laboratÃrios entrevistados. Isso poderà refletir na comunidade cientÃfica uma confiabilidade em decorrÃncia da implantaÃÃo de procedimentos e tÃcnicas padronizadas e no futuro permitirà que os laboratÃrios possam ser credenciados na - REBLAS, conferindo seguranÃa aos pesquisadores, bem como, reprodutibilidade dos resultados. / To make possible the implantation of management techniques and good practice of laboratory on the Brazilian Net of Laboratories - REBLAS from an evaluation of diagnosis, for the application of questionnaires in laboratories of public institutions of superior education and health research, in four Brazilian capitals. Methodology: The research was carried through visits in laboratories of institutions of superior education and health research, to diagnosis the situation of them by interviews with application of questionnaires. The size of the sample was in fifty (50) researchers, distributed in institutions of education and research of four (04) Brazilian capitals. In each institution had been selected a laboratories and identified the responsible researchers to be interviewed. After that, a diagnosis of the situation of the laboratories was elaborated, and been compared with previously existing models of good practice of laboratory in literature, which had been evaluated and lead under absolute secrecy, in order to keep the integrity of the laboratories and institutions in question. Results: through the diagnosis of the laboratories were developed models of good practice of laboratory and quality warranty (operational procedures standard and forms), which could be implanted and be implemented in laboratories of institutions of existing health education and research in Brazil. Conclusion: The theoretical conceptions that had based the study had been analyzed and compared with the theoretical research and on field and had made possible the choice and elaboration of management techniques and standardized procedures in function of the diagnosis of the interviewed laboratories. This will be able to reflect trust in the scientific community through the implantation of procedures and standardized techniques and in the future those laboratories may be credential in the REBLAS, conferring security to the researchers, as well as, credibility of the results.

No description available.

Thesis (MScMedSc (Pathology. Medical Microbiology))--University of Stellenbosch, 2010. / ENGLISH ABSTRACT: INTRODUCTION Mycobacterium tuberculosis (MTB) and Cryptococcus neoformans are the most common causes of chronic meningitis in South Africa. Conventional microbiology has limited utility in diagnosing these pathogens due to the paucibacillary nature of cerebrospinal fluid (CSF) and the diagnostic delay associated with culturing methods. This study aimed to evaluate the utility of an in-house polymerase chain reaction (PCR) method for the detection of the etiological agent of chronic meningitis. METHODS CSF samples (where volume exceeded 5ml) were submitted to the Medical Microbiology diagnostic laboratory of the Tygerberg Hospital from patients with suspected tuberculosis meningitis (TBM). Following routine bacteriology, the sample was used to inoculate two mycobacterial growth indicator tubes (MGIT A and B) and subsequently incubated in the BACTEC 960 automated system. MGIT A followed standard operating procedures and the time to culture positivity was noted. Weekly aliquots (up to 6 weeks) were removed from MGIT B. These samples were boiled to inactivate the bacteria and then the DNA was extracted using the Promega Wizard SV Genomic DNA kit. The DNA was then speciated by PCR and high-resolution melting analysis (HRM) by using primers specific to either the RD9 region of MTB complex or primers specific to the partial internal transcribed spacer 1 (ITS1), 5.8S rRNA gene and partial ITS2 sequence of C. neoformans. RESULTS Routine CSF microscopy indicated that 14 of the 78 patients (17.9%) had typical CSF findings of TBM (lymphocytes predominant, increased protein levels and decreased glucose levels). IV Ziehl-Neelsen (ZN) stains were positive for 12 (15.4%) samples, and MTB was cultured from 19 samples (24.4%). Our optimized PCR and HRM method was able to detect M. tuberculosis in 17 of the 19 culture positive specimens with a sensitivity of 89.5% and a specificity of 62.7%. The sensitivity of this method was higher than that of direct microscopy. In all of the PCR positive samples, the time to detection, compared to culture, could be shortened by 1 to 2 weeks. Only one sample was positive for Cryptococcus culture and another sample was positive with a Cryptococcus latex test. PCR for Cryptococcus was positive in 2 cases (n=78), sensitivities and specificities could not be reported due to the low number of positive cases. CONCLUSION We demonstrated that a short culture period and the use of commercial DNA extraction kit on CSF samples increases the sensitivity of molecular tests to diagnose tuberculosis. Furthermore, the molecular techniques could significantly reduce the time to positivity of results, when compared to culture. Due to the low occurrence of Cryptococcus in the samples included in our study, we could not comment on the diagnostic utility of PCR in the diagnosis of Cryptococcal meningitis, when compared to the conventional methods. / AFRIKAANSE OPSOMMING: INLEIDING Mycobacterium tuberculosis (MTB) en Cryptococcus neoformans is die mees algemeenste oorsake van kroniese meningitis in Suid-Afrika. Routine mikroskopie dra beperkte waarde in die diagnose van hierdie patogene as gevolg van die klein hoeveelhede organismes wat in die SSV (serobrospinale vog) voorkom en die lang tyd wat dit benodig om hierdie organisms te kweek. Hierdie studie beoog om die diagnostiese waarde van ‘n polymerase ketting reaksie (PKR) metode wat intern ontwerp is te evalueer vir die identifikasie van patogene verantwoordelik vir kroniese meningitis. METODES SSV monsters (waarvan die volume 5ml oorskry) en waar daar ‘n kliniese vermoede van tuberkulose meningitis (TBM) was, is na die diagnostiese Mediese Mikrobiologie laboratorium van Tygerberg hospitaal gestuur vir roetine bakteriologiese ontleding. Die oorblywende monsters is gebruik om twee mikobakteriële groei-indikasiebuise (MGIT A en B) te innokuleer en hulle is geïnkubeer in ‘n BACTEC 960 geautomatiseerde sisteem. MGIT A is volgens roetine diagnostiese metodes geanaliseer en die tyd tot ‘n positiewe resultaat is aangeteken Weeklikse monsters (tot en met week 6) is uit MGIT B verwyder en die monsters is gekook om sodoende die bakterië te inaktiveer. Die Promega Wizard SV Genomiese DNS ekstraksiemetode is gebruik om die DNS te versuiwer. Spesiëring van die DNS is deur middel van ‘n intern ontwerpte PKR en hoëresolusiesmeltingsmetode (HRS) gedoen met inleiers wat spesifiek is tot die RD9 gedeelte van die MTB kompleks en inleiers spesifiek tot die gedeeltelike interne getranskribeerde spasieerder 1 (ITS1), 5.8S rRNS geen en die gedeeltelike ITS2 DNS volgorde van C. neoformans. VI RESULTATE Roetine SSV mikroskopie het aangedui dat 14 uit 78 (17.9%) pasiënte tipiese SSV bevindings van TBM (oorwegend limfosiete, verhoogde proteïene en verlaagde glukose) gehad het. Ziehl- Neelsen (ZN) kleurings was positief vir 12 (15.4%) monsters, en MTB is gekweek in 19 (24.4%) van hierdie monsters. Ons geoptimaliseerde PKR en HRS metode het daarin geslaag om M. tuberculosis in 17 van die 19 kultuurpositiewe monsters aan te toon met ‘n sensitiviteit van 89.5% en ‘n spesifisitiet van 62.7%. Die sensitiwiteit van die direkte PKR was hoër in vergelyking met mikroskopie. In al die PKR positiewe monsters was die tyd tot aantoning, in vergelyking met kultuur, verkort met 1 tot 2 weke. Slegs een monster het C. neoformans gekweek en ‘n ander monster was positief met die kriptokokkale latekstoets. PKR vir C. neoformans was positief in 2 gevalle (n=78). Die sensitiwiteit en spesifisiteit van die C. neoformans PKR kon nie bepaal word nie weens te min gevalle. GEVOLGTREKKINGS Ons het aangetoon dat ‘n verkorte inkubasieperiode en die gebruik van ‘n kommersiële DNS ekstraksiemetode op SSV monsters die sensitiwiteit van die molekulêre tegniek vir die diagnose van tuberkulose verhoog en dat hierdie metode die tyd na positiwiteit aansienlik verkort in vergelyking met kultuur. Weens die lae getalle van kriptokokkale meningitis in ons studie kon ons nie kommentaar lewer op die akkuraatheid van PKR in die diagnose van kriptokokkale meningitis, in vergelyking met meer konvensionele metodes, nie.

A giardíase é uma doença entérica de alta prevalência particularmente nos países em desenvolvimento. Diferentes espécies foram descritas em função de seus hospedeiros. A G. duodenalis é a espécie que parasito não só o homem, mas também animais domésticos e silvestres. Recentemente, com a aplicação de técnicas moleculares, foi possível identificar sete diferentes agrupamentos sendo que cada um deles tem predileção por determinadas espécies de hospedeiro. Essa discriminação não é possível por meio da microscopia. A identificação do(s) agrupamento(s) presente(s) na população de determinada região pode ser de grande importância na elaboração de políticas de saúde pública já que revela o perfil de transmissão desse protozoário. Este estudo teve por objetivos verificar o grau de positividade de enteroparasitos, a contribuição de cada um deles nesse índice e o genótipo dos cistos de G. duodenalis presentes em amostras de fezes de indivíduos atendidos no Hospital Universitário da Universidade de São Paulo. Foram analisadas 6717 amostras com positividade para algum enteroparasito de 12,5%, sendo S.stercoralis e G. duodenais respectivamente o helminto e protozoário patogênico mais frequentes. A maioria dos casos de G. duodenalis genotipada era dos agrupamentos AII e B. / Giardiasis is a very prevalent enteric disease occurring mainly in developing countries. Different species have been described concerning their hosts. G. duodenalis parasites not only men but also domestic and wild animals. Recently molecular techniques have been used to identify seven different assemblages which parasites specific hosts. The microscopic analysis do not allows that discrimination. It can be useful to know the assemblage profile of specific population in order to provide some important information to built public health politicies once it reveals the transmition of the protozoan The aim of this study was to verify the enteroparasites infection degree, the individual contribution of each one in this picture and to genotyping G. duodenalis cysts from human faecal samples of individuals from University Hospital from Universty of São Paulo. So, 6717 faecal samples were analysed and 12,5% were positive for some enteroparasite and S.stercoralis and G. duodenais were the helminth e pathogenic protozoan more frequently found. Most of the cases of G. duodenalis were from the assemblages AII and B.

Os antibióticos beta-lactâmicos, principalmente as aminopenicilinas (ampicilina e amoxicilina) são causa freqüente de exantema maculo papular e urticária tardia em pacientes tratados com estes medicamentos. Entretanto, a falta de métodos para diagnóstico destas reações constitui uma lacuna na abordagem destes indivíduos. Objetivos: Os objetivos deste estudo foram determinara a freqüência e significância de testes cutâneos positivos em pacientes com história de exantema maculo-papular e urticária tardias induzidos por antibióticos beta-lactâmicos e determinar a sensibilidade e especificade dos testes diagnósticos in vitro para o diagnóstico de alergia a drogas: proliferação linfocitária e dosagem de citocinas no sobrenadante da cultura linfocitária.. Métodos: Os pacientes foram submetidos à dosagem de IgE específica para os seguintes determinantes: benzilpeniciloil, amoxiciloil e ampiciloil. Testes cutâneos de puntura e intradérmico com benzilpeniciloil polilisina, mistura de determinantes menores da penicilina, benzilpenicilina (10.000 UI/ml), amoxicilina (2 mg/ml) e ampicilina (2mg/ml) foram realizados em todos os pacientes com leituras após 20 minutos, 48 horas e 72 horas. Foi realizado teste de contato com os mesmos medicamentos (amoxicilina 5%, ampicilina 5% e penicilina G 5000UI/g de vaselina sólida). Todos os testes foram feitos em duplicata com controles positivo e negativo. Amostras de sangue foram coletadas para a proliferação linfocitária (incorporação de timidina triciada) e dosagem de citocinas no sobrenadante da cultura (IL-5, IFN-gama e TNF- 17 alfa) através de ELISA. Resultados: Foram estudados 20 pacientes e 15 controles. Nenhum dos pacientes ou controles apresentou teste cutâneo de leitura imediata positivo. Três pacientes reagiram positivamente aos testes cutâneos de leitura tardia nas leituras de 48 e 72 horas. Não houve nenhum resultado positivo dos testes cutâneos no grupo controle. A proliferação linfocitária mostrou-se positiva em somente 2 controles (13%) e 10 pacientes (50%). A sensibilidade dos experimentos de proliferações linfocitária variou entre 25% com penicilina na concentração de 250 ?g/ml até 55% com ampicilina 1000 ?g/ml. Sua especificidade foi de 80% a 100%. Conclusão: os testes cutâneos de leitura tardia não constituíram métodos diagnósticos eficazes para as reações tardias aos antibióticos beta-lactâmicos. A proliferação linfocitária apresentou baixa sensibilidade, porém, alta especificidade para o diagnóstico das mesmas reações. A detecção de IFN-gama e IL-5 evidenciaram alta especificidade e baixa sensibilidade, enquanto a dosagem de TNF-alfa mostrou-se altamente sensível (95%), porém, pouco específica (40%) / The beta-lactam antibiotic, mainly aminopenicillins: ampicillin (AMP) and amoxicillin (AMX), are frequently cited as causes of morbiliforme eruptions and late onset urticaria. A major problem with existing data on beta-lactam reactions of the delayed type includes a lack of standardized testing methods. Objectives: The goal of this study is to establish the frequency and significance of positive skin testing in patients with history of beta-lactam induced maculo-papular exanthema and late onset urticaria and the sensibility/specificity of in vitro tests for drug allergy investigation: lymphocyte proliferation assay and cytokine detection. Methods: Patients were submitted to complete penicillin (PEN) allergy test: specific detection for serum IgE antibody to benzyl penicilloyl polylysine, amoxicilloyl polylysine and ampicilloyl polylysine; puncture and intradermal skin test with benzyl penicilloyl polylysine and minor determinants mixture, benzylpenicillin (10.000 UI/ml), amoxicillin (2mg/ml), ampicillin (2mg/ml) were performed and read at 20 minutes, 48hours and 72 hours. All patients had epicutaneous patch testing done with the same drugs (5% amoxicillin, 5% ampicillin and 5000 IU/g penicillin G all in petrolatum). All tests were performed in duplicate with positive and negative controls. All subjects had blood collected for lymphocyte proliferation assay (H3-thymidine incorporation assay) and IL-5, TNF-alpha and IFN-gamma profile were analyzed in culture supernatant by ELISA. Results: None of the patients or controls had positive immediated skin test. Only three patients reacted positively to the 48 and 72 hours 15 reading of intradermal skin test and patch test with the same reagents. There was no positive skin test result among the control group. The lymphocyte proliferation test (LTT) was positive in only two control subjects, while in the study group, 10 patients had positive proliferation tests (50%). The LTT sensitivity varied from 25% to 55% depending on the drug and concentration tested. The specificity ranged from 80% to 100%. IFN-gamma and IL-5 detection had a high specificity, but low sensitivity, while TNF-alpha showed high sensitivity (95%) and low specificity (40%)

Recentemente, foi descrito um grupo de alterações no metabolismo da creatina denominado Síndromes de Deficiência de Creatina. Há três formas da doença geneticamente determinadas que cursam com deficiência de creatina, seja por comprometimento de sua síntese ou por defeito na proteína transportadora. O espectro de apresentação clínica dessa condição é inespecífico e inclui atraso ou estagnação do desenvolvimento neuromotor, hipotonia muscular, movimentos involuntários do tipo coreoatetose, retardo ou ausência do desenvolvimento da fala, retardo mental de grau variável, comportamento autista e epilepsia. Neste trabalho, foi desenvolvida e validada uma alternativa metodológica àquelas disponíveis na literatura, com a utilização de extração por troca catiônica forte e separação e detecção por cromatografia líquida de interação hidrofílica acoplada a espectrometria de massas em tandem em que foram exploradas as características químicas das moléculas de creatina e guanidinoacetato, metabólito intermediário da síntese de creatina. Os valores de referência para o método foram definidos pela sua aplicação a 150 amostras de urina e 197 amostras de soro de indivíduos de ambos os sexos e idades entre 0 e 16 anos. Foram também analisadas amostras de urina, soro e plasma de 54 pacientes com clínica compatível com a síndrome de deficiência de creatina sendo que 3 deles apresentaram perfil bioquímico característico de uma das formas dessa condição / Recently, a new group of inborn errors of metabolism, collectively named as creatine deficiency syndrome, was identified. Three genetically determined presentations are currently known, affecting both creatine synthesis and transport. Clinical presentation spectrum is non-specific and includes developmental delay, hypotonia, involuntary movements as choreoathetosis, delay or lack of speech acquisition, mental retardation of variable severity, autistic behavior, and epilepsy. Herein, we developed and validated an innovative method for determination of creatine and of its metabolic intermediate, guanidinoacetate, based on cation-exchange solid-phase extraction and hydrophilic interaction liquid chromatography coupled to tandem mass spectrometry. Reference values for the method were defined testing 150 urine and 197 serum samples in males and females with age ranging from 0 to 16 years. Urine and serum samples from 54 patients with some clinical features that might be attributable to creatine deficiency were also evaluated, and in three, biochemical profile characteristic of one of the disorders was detected