Endogenous production of nitrate in patients with infective gastroenteritis is increased manifold, and this increase originates from endogenous production of nitric oxide via the enzymatic L-arginine-NO pathway. Endogenous nitrate production seems to be a specific feature of infective gastroenteritis; no significant increase is observed in non-infective diarrhoeal conditions, and the production during other infective conditions such as septicaemia is comparatively modest. Twenty four hours urinary nitrate excretion after a period of minimal oral nitrate intake is the golden standard for measuring endogenous nitrate production, but is difficult to implement and prone to sampling errors. The urinary nitrate/creatinine ratio appears a satisfactory alternative provided that a standardised collection procedure is carried out. The urinary ratio reveals differences in endogenous nitrate production that remain undisclosed with serum nitrate measurements. Addition of nitrite achieves kill of micro-organisms where acid alone allows growth to continue. The synergism in antimicrobial action of acid and nitrite is evident against common gut pathogens such as the <I>Enterobacteriaceae</I>, including <I>E. coli 0157, </I>but also against the stomach pathogen <I>H pylori, </I>normally very resistant to acid alone. The antibacterial action of acidified nitrite becomes apparent at physiological concentrations of acid and nitrite after exposure times that are within the passage time of a food bolus through the stomach. Acidified nitrite also has an antifungal effect against <I>Candida albicans, </I>however at concentrations of acid and nitrite not normally found in the human upper gastro-intestinal tract. The antimicrobial activity of acidified nitrite is enhanced by thiocyanate, also present in gastric juices. Ascorbic acid provides protection against the antibacterial action of acidified nitrite, suggesting that NO is not the antibacterial agent. Acidification of salivary nitrite in the stomach will increase host defence against ingested pathogens. Generation of salivary nitrite increases greatly after nitrate ingestion, suggesting that ingestion of foods rich in nitrate may protect against infective gastroenteritis.

Thesis (Ph. D.)--Michigan State University. Dept. of Microbiology and Molecular Genetics, 2007. / Title from PDF t.p. (viewed on Apr. 16, 2009) Includes bibliographical references. Also issued in print.

No description available.

published_or_final_version / abstract / Microbiology / Doctoral / Doctor of Philosophy

No description available.

Artículo sustentado el 30 de Enero 2014 para la obtención del título profesional Médico Cirujano en la Escuela de Medicina, Facultad de Ciencias de la Salud. Universidad Peruana de Ciencias Aplicadas - UPC. / Artículo publicado el 27 de Abril de 2014 en la Revista Transactions of the Royal Society of Tropical Medicine & Hygiene (Oxford University Press). / Background: Gastroenteritis by rotavirus is responsible for approximately 810 annual deaths/year in children under 5 years in Peru and emerging rotavirus genotypes have led to concerns regarding cross-protection by the vaccines available. Moreover, there are no reports on the molecular-epidemiology of rotavirus diarrhea in Peru Methodology: A total of 131 stool samples were obtained from children under 5 years old hospitalized from January 2010 to December 2012 in the Hospital Regional de Cajamarca, Peru. ELISA and RT-PCR techniques were performed for rotavirus detection. G and P typing of rotavirus-positive samples were obtained by semi-nested multiplex RT-PCR and sequencing was performed to confirm the PCR results. Results: Of the 117 samples available, 18.80% (22/117) tested positive for rotavirus by ELISA and 35.90% (42/117) by RT-PCR. Among the G-genotype identified, G9 in 35.71% (15/42) and G12 in 33.33% (14/42) were the most prevalent. With the most common combination being G12/P6 in 23.81% (10/42). Conclusions: A high prevalence of the G12/P6 genotype was detected. It is know that this genotype is not covered by the current vaccines available. More in depth studies are needed to know the current rotavirus genotypes presents in Peru.

No description available.

Memoria para optar al Título Profesional de Médico Veterinario / En medicina veterinaria de pequeños animales se registra comúnmente el Síndrome Gastroenteritis Hemorrágica (SGEH), que constituye una de las causas frecuentes de primera consulta. Se consideraron en este estudio las fichas médicas recopiladas entre el 1 de enero de 2000 y el 31 de diciembre de 2008 de la Clínica Veterinaria “Diego Silva”, ubicada en Santiago, comuna de Conchalí, la cual fue fundada en el año 1979 y presenta una alta casuística. Se tomaron los casos diagnosticados con SGEH de perros menores de un año, rescatándose la siguiente información: número de ficha, fecha del diagnóstico, edad del paciente, raza, domicilio del dueño y presencia de vacunas previas. De la revisión de 17.882 fichas, se reportaron 842 casos con signos clínicos de SGEH en los 9 años en estudio, de los cuales 61% eran machos y 39% hembras. Al 95% de ellos no se les había aplicado vacuna alguna y más de la mitad era de raza mestiza. Se localizaron espacialmente los domicilios de los afectados a través de la georreferenciación y del uso del Sistema de Información Geográfica (SIG) llamado ArcGis®. Sobre una base cartográfica de la comuna se ubicaron los datos agregados para describir el comportamiento espacial de la enfermedad mediante la autocorrelación espacial dada por el Índice I de Moran. Por otra parte, también se evaluó el comportamiento temporal de la enfermedad en los 9 años, mediante la elaboración de corredores endémicos. Espacialmente se encontró un mayor número de casos en el norte de la comuna en 8 de los 9 años evaluados y en 4 años se observó un alto número de casos en el suroriente de la comuna, mientras en el centro de la comuna los casos se presentaron con mayor dispersión en todos los años considerados. El índice I de Moran indicó presencia de pequeños conglomerados a nivel general. En cuanto a la presentación temporal, se observó un aumento de casos de SGEH en temporadas de transición como es en otoño y primavera y una disminución de los casos en los meses de invierno. El presente trabajo constituye un primer diagnóstico de la realidad espacio-temporal de casos de SGEH, cuya información puede ser útil para que clínicas veterinarias y organismos encargados del registro de enfermedades infecciosas en pequeños animales puedan orientar el control y la prevención de la enfermedad en perros jóvenes

Els calicivirus humans (HuCV) són una causa important de brots de gastroenteritis (GEA) en adults, el paper però d'aquests virus com a causa de casos esporàdics de GEA en nens és desconegutObjectius1. Estudiar la prevalença i les característiques clíniques del les infeccions per HuCV en nens hospitalitzats als USA2. Determinar la diversitat genètica dels HuCV causants d'aquesta patologia3. Determinar el cost mèdic derivat d'aquestes infeccionsMetodesEs va realitzar un estudi prospectiu a tres hospitals pediàtrics dels USA, a Cincinnati, OH; Oakland, CA; i Norfolk, VA. Nens de 14 dies fins a 5 anys d'edat ingressats per un quadre de diarrea, vòmits o febre sense causa de menys de 7 dies d'evolució van ser inclosos. Es van recollir dades clíniques i demogràfiques, així com una mostra de femta. La femta es va analitzar per la presencia de rotavirus (RV) per EIA i per HuCV per RT-PCR utilitzant els cebadors 289/290 i 289hi/290hijk, dirigits a la regió de la polimerasa i que són capaços de detectar NLV i SLV. Totes les mostres positives per RT-PCR van ser confirmades per sequenciació utilitzant SequiTherm EXCEL II long-Read DNA Sequencing kit-ALF en un seqüenciador automàtic. Els arbres filogenètics es van obternir utilitzant l'algoritme de Maximum likelihood. Es va calcular el cost del periode pre, hospitalització i posthospitalització a partir del nombre de visites a serveis mèdics, les medicacions prescrites, les exploracions complementàries solicitades i el cost de la hospitalització. ResultatsEs van obtenir 1844 mostres. Es van detectar RV en 27% de les mostres i HuCV en un 8%. Dels 155 HuCV, 25 eren SLVs i 130 NLVs. L'edat dels pacients infectats per RV era superior a la dels infectats per HuCV (mitjana 13 mesos vs 8 mesos). Els RV van mostrar un predomini estacional durant l'hivern, mentre que els HuCV van ser més freqüents a finals d'hivern-principis de primavera. Es va detectar co-infecció amb RV en 12% dels pacients infectats per HuCV. El símptoma més freqüent en les infeccions per HuCV van ser els vòmits (79% dels pacients). La febre va ser el signe més freqüent en nens de menys de 3 mesos d'edat. La gravetat dels quadres produits per SLV i NLV van ser similars. La mitjana de cost per pacient va ser de $3,574 (interval $820-$116,088).L'analisi filogenètic de les soques aïllades mostrà 3 soques pertanyent als SLV amb menys d'un 70% d'identitat amb les soques de referència i 7 NLV que no pertanyien a cap dels dos genotips, mostrant menys d'un 65% identitat a nivell nucleòtid amb les soques de referènciaConclusions Els HuCVs són una causa important de GEA en nens als USA, afectant pacients de menor edat que els RV i mostrant un patró estacional diferent.Els HuCV causant de GEA són geneticament diversos. No es van poder demostrar diferències en la presentació clínica ni en les característiques epidemiològiques de les infeccions pels diferents géneres.El cost economic i social d'aquestes infeccions és important / Human calicivirus (HuCV) are an important cause of gastroenteritis (AGE) outbreaks in adults but the role of this virus as a cause of sporadic gastroenteritis in children is not known.Objectives1. To asses the prevalence and clinical characteristics of HuCV infection among children resulting in hospitalization in the USA.2. To determine the genetic diversity of the HuCV causing this severe illness3. To determine the direct medical cost and burden cause by these infections MethodsPatients were enrolled in a longitudinal prospective maneer at three pediatric hospitals in Cincinnati, OH; Oakland, CA; and Norfolk, VA. Children 14 days to 5 years of age admitted because of diarrhea, vomiting or fever of less than 7 days duration at admission were enrolled. Clinical and demografic information were collected, as well a stool sample. Stools were tested for rotavirus (RV) by EIA and stored at -70ºC until being tested for HuCV. Samples were tested for HuCV by RT-PCR using primers 289/290 and 289hi/290hijk targeting the polimerase region and able to detect NLV and SLV. All the positives by RT-PCR were confirmed by sequencing using SequiTherm EXCEL II long-Read DNA Sequencing kit-ALF on an automated sequencer. Phylogenetic trees were obtained using Maximum likelihood algoritm. The cost of pre, hospitalization and posthospitalization period was calculated based on the cost of visits to a health care provider, tests ordered, medications prescribed and cost of hospitalization. Results1844 samples were available for testing. The detection rates for RV and HuCV were 27% and 8% respectively. Of 155 samples positive for HuCV, 25 were SLVs and 130 NLVs. Patients infected by RV were older than those infected by HuCV (median 13 months vs 8 months). RV had winter seasonality while HuCV was more frequent during late winter/early spring. Co-infection with RV occurred in 12% of the HuCV -positive patients. The most common symptom in HuCV infected patients was vomiting (79%). SLV was associated with more vomiting (86%) compared to NLV (79%). Fever was a frequent symptom, specially in children less than 3 months of age. Severity for SLV and NLV were similar. The median cost for calicivirus infected patients was $3,574 (range $820-$116,088).Phylogenetic analysis of the isolated strains showed 3 SLV samples that were less than 75% identical to the reference strains. Seven of the NLV strains did not fall in any ot the two genotypes showing less than 65% identity at nucleotide level to any of the reference strains.Conclusions HuCVs are a relevant cause of severe AGE in children in USA. Seasonality and epidemiology for RV was different than for HuCV.HuCV causing AGE in children are genetically diverse. No differences regarding clinical presentation and demographic characteristics could be proved for the different genera or clusters.HuCV infection has an important economical and social cost.

Background: Rotavirus is one of the most common diarrheal diseases in children less than 5 years of age. Rotavirus vaccines have greatly reduced this burden in the United States. An examination was conducted to determine possible disparities in RV vaccination rates compared to DTaP. Methods: Children were actively enrolled during two rotavirus seasons from January-June of 2010 and 2011 in the Emergency Departments (ED) and inpatient floors from all Children's Healthcare of Atlanta (CHOA) sites (Scottish Rite, Egleston, and Hughes Spalding) with acute gastroenteritis (AGE). Data and a stool sample were collected from enrolled children and samples were tested for presence of rotavirus using an enzyme immunoassay (EIA) kit (Rotaclone). Vaccination records were abstracted from the state immunization registry and primary healthcare providers to examine complete and incomplete vaccination status. This cohort of children with vaccination records were used for this analysis. Cases were identified as children receiving a complete RV dose series and controls were identified as children with incomplete RV doses. A logistic regression model was used to determine disparities seen amongst children with incomplete vaccination status. Results: Of the 660 patients that were approached for this study, 414 participants were included in this retrospective cohort analysis. 46.9% had incomplete rotavirus vaccination status and were more likely to be positive for rotavirus AGE (OR 1.76, 95% CI 1.46-2.13). Black infants had a higher rate of incomplete RV compared to whites (p-value 0.0006). When controlling for covariates, racial differences were no longer significant (OR 1.37 95% CI 0.77-2.57); however household size (p-value 0.0343), age at onset of illness (p-value 0.0061), and DTaP vaccination status (p-value < 0.0001) were all significant in determining vaccination status for children. Conclusions: Racial disparities and socioeconomic differences are not evident in determining rotavirus vaccination rates; however, household size, a possible social determinant, has an effect on RV status. In addition, timely vaccinations are important in preventing incomplete RV vaccination status, due to RV vaccine age restrictions.