Helicobacter pylori infection: A balance between bacteria and host / Helicobacter pylori: un balance entre bacterias y huésped

Abstract In Argentina, despite the important studies conducted on the prevalence of infection and the antibiotic resistance of Helicobacter pylori, there are no reports simultaneously analyzing a profile of virulence factors of the bacterium and polymorphisms in cytokine genes in patients with different alterations in the gastric mucosa (including intestinal metaplasia, IM). Our aim was to evaluate H. pylori genotypes in 132 adult patients with chronic gastritis presenting three different histological findings (inactive chronic gastritis, active chronic gastritis IM( and active chronic gastritis IM+) along with SNP-174 G>C in the IL-6 gene. cagA, vacA and babA2 genes were analyzed by multiplex PCR. The -174 G>C SNP IL-6 gene was analyzed by PCR-RFLP. Patients with active chronic gastritis IM+ showed the highest proportion of the cagA(+)/IL-6GG, cagA(+)/vacAm1s1/IL-6GG and cagA(+)/vacAm1s1/babA2(+)/IL-6GG combinations (p<0.05). There was 4-5 times greater probability of finding patients presenting the GG genotype for SNP-174 G>C IL-6, which in turn were infected with the most virulent H. pylori genotypes -cagA(+), cagA(+)/vacAm1s1 and cagA(+)/vacAm1s1/babA2- in the ACGIM+ group in comparison to the ICG group. Our results provide regional data to the idea that the transition towards severe alterations in the gastric mucosa would be the result of a balance between specific factors of H. pylori and inherent host factors. This fact can be useful to identify patients at greater risk and to select those individuals requiring appropriate eradication treatment to prevent progression to gastric cancer.

Resumen En Argentina, a pesar de los importantes estudios realizados sobre la prevalencia de infección y la resistencia a antibióticos de Helicobacter pylori, no existen reportes que analicen simultáneamente un perfil de factores de virulencia de la bacteria y polimorfismos en genes de citoquinas en pacientes con diferentes alteraciones en la mucosa gástrica (incluida la metaplasia intestinal [MI]). Nuestro objetivo fue evaluar genotipos de H. pylori en 132 pacientes adultos con gastritis crónica, con tres diferentes hallazgos histológicos (gastritis crónica inactiva [GCI], gastritis crónica activa [MI(] y gastritis crónica activa [MI+]), junto con el SNP-174 G>C en el gen de IL- 6. Los genes cagA, vacA y babA2 se analizaron mediante PCR multiplex. El SNP-174 G>C IL-6 se analizó mediante PCR-RFLP. Los pacientes con gastritis crónica activa MI+ mostraron la mayor proporción de combinaciones cagA(+)/IL-6GG, cagA(+)/vacAm1s1/IL-6GG y cagA(+)/vacAm1s1/babA2(+)/IL-6GG (p<0,05). Hubo 4-5 veces mayor probabilidad de encontrar pacientes con el genotipo GG en SNP-174 G>C IL-6 y a su vez infectados con los genotipos más virulentos de H. pylori-cagA(+), cagA(+)/vacAm1s1 y cagA(+)/vacAm1s1/babA2-en el grupo gastritis crónica activa MI+ en comparación con el grupo GCI. Nuestros resultados aportan datos regionales a la idea de que la transición hacia alteraciones más graves en la mucosa gástrica resultaría de un equilibrio entre factores específicos de H. pylori y factores inherentes al huésped. Esto puede ser útil para identificar pacientes con mayor riesgo y seleccionar aquellos individuos que requieran un apropiado tratamiento de erradicación para prevenir la progresión al cáncer gástrico.

Helicobacter pylori infection: A balance between bacteria and host.

In Argentina, despite the important studies conducted on the prevalence of infection and the antibiotic resistance of Helicobacter pylori, there are no reports simultaneously analyzing a profile of virulence factors of the bacterium and polymorphisms in cytokine genes in patients with different alterations in the gastric mucosa (including intestinal metaplasia, IM). Our aim was to evaluate H. pylori genotypes in 132 adult patients with chronic gastritis presenting three different histological findings (inactive chronic gastritis, active chronic gastritis IM- and active chronic gastritis IM+) along with SNP-174 G>C in the IL-6 gene. cagA, vacA and babA2 genes were analyzed by multiplex PCR. The -174 G>C SNP IL-6 gene was analyzed by PCR-RFLP. Patients with active chronic gastritis IM+ showed the highest proportion of the cagA(+)/IL-6GG, cagA(+)/vacAm1s1/IL-6GG and cagA(+)/vacAm1s1/babA2(+)/IL-6GG combinations (p<0.05). There was 4-5 times greater probability of finding patients presenting the GG genotype for SNP-174 G>C IL-6, which in turn were infected with the most virulent H. pylori genotypes -cagA(+), cagA(+)/vacAm1s1 and cagA(+)/vacAm1s1/babA2- in the ACGIM+ group in comparison to the ICG group. Our results provide regional data to the idea that the transition towards severe alterations in the gastric mucosa would be the result of a balance between specific factors of H. pylori and inherent host factors. This fact can be useful to identify patients at greater risk and to select those individuals requiring appropriate eradication treatment to prevent progression to gastric cancer.

ERIC-PCR technique applied to monitoring and quantification of DNA damage during water disinfection process.

In this work, we propose a novel application of ERIC-PCR technique to study DNA damage after ultraviolet radiation (UV) and peracetic acid (PAA) treatment for water disinfection purpose. The efficacy of both treatments on E. coli suspension was evaluated by two approaches: through monitoring of inactivation by conventional culture technique, and by analyzing DNA damage with ERIC-PCR. All the experiments were carried out in a batch reactor, using three intensities of UV-C radiation (10.5, 4.2 and 2.1 mW/cm2) and different PAA concentrations (4 to 16 ppm). Both treatments produced bacterial inactivation in a dose-response fashion. Based on the results of bacterial count we obtained an index of inactivation (INACI). For each sample, DNA extraction was performed and evaluated by ERIC-PCR. Qualitative modifications were observed in ERIC-PCR band patterns for all the UV-C radiation intensities used, but no changes were detected at any of the PAA concentrations. The banding pattern modifications observed are consequence of the interruption of Taq polymerase enzyme amplification-activity, caused by the presence of alterations on the DNA structure (dimer and hydrates formation). Furthermore, an index was proposed to measure DNA damage (DNADI) regarding the changes in the relative optical density values of the amplification products. A linear correlation was obtained with a high correspondence between the inactivation index (INACI) and the DNA damage index (DNADI), that was expressed as DNADI = 0.05881×INACI. This approach proves that ERIC-PCR is a feasible and valuable tool for detecting and quantifying DNA damage and it may provide a useful strategy for bacterial identification, tracking changes in DNA and providing reliable and reproducible data.

Usefulness of rapid urease test samples for molecular analysis of clarithromycin resistance in Helicobacter pylori / Utilidad de las muestras de test rápido de ureasa para el análisis molecular de resistencia a claritromicina en Helicobacter pylori

Helicobacter pylori is a gastric pathogen that is widely recognized as a causative agent of gastric disease. Its eradication is variable, mainly due to increased resistance to clarithromycin. Our objective was: to evaluate (i) if the biopsy specimen used for the rapid urease test is a useful sample to detect resistance to clarithromycin by PCR-RFLP and (ii) the distribution of A2142G and A2143G point mutations in the 23S rRNA gene, in relation to virulence factors in our region. Gastric specimens were collected from adult dyspeptic patients (n = 141) and H. pylori was investigated by the rapid urease test, histopathological analysis and PCR for the hsp60 gene. Clarithromycin resistance was detected by PCR-RFLP in 62 H. pylori (+) paired biopsy specimens submitted to molecular analysis and the rapid urease test. H. pylori virulence factors were analyzed by multiplex PCR using specific primers for the cagA, vacA and babA2 genes. Thirteen out of 62 strains (20.9%) were resistant to clarithromycin: 6/13 (46.2%) harbored the A2143G mutation whereas 7/13 (53.8%) carried the A2142G point mutation. vacA m1s1 was the most frequent genotype among the resistant strains. In conclusion, the biopsy specimens used for the rapid urease test were suitable samples for clarithromycin resistance detection in patients infected with H. pylori, which became especially useful in cases where the number or size of the biopsies is limited. In addition, this is the first report of a molecular analysis for clarithromycin resistance performed directly from gastric biopsies in our region.

Helicobacter pylori es un patógeno ampliamente reconocido como causante de enfermedad gástrica. Su erradicación es variable, principalmente debido al incremento de la resistencia a claritromicina. Nuestros objetivos fueron evaluar la utilidad de la biopsia usada para realizar el test rápido de ureasa en la detección de resistencia a claritromicina por PCR-RFLP y conocer la distribución de las mutaciones puntuales A2142G y A2143G en el gen ARNr 23S, en relación con los factores de virulencia en nuestra región. Se recolectaron muestras gástricas (n=141) provenientes de pacientes adultos dispépticos y se investigó la presencia de H. pylori mediante el test rápido de ureasa, análisis histopatológico y PCR para el gen hsp60. La resistencia a claritromicina se analizó por PCR-RFLP en 62 muestras pareadas de biopsias gástricas H. pylori+ destinadas al análisis molecular y al test rápido de ureasa. Los factores de virulencia de H. pylori fueron analizados mediante PCR multiplex usando oligonucleótidos específicos para los genes cagA, vacA y babA2. Trece de 62 cepas (20,9%) fueron resistentes a claritromicina, 6/13 (46,2%) llevaron la mutación A2143G, mientras que 7/13 (53,8%) presentaron la mutación A2142G. El genotipo vacA s1m1 fue el más frecuente entre las cepas resistentes a claritromicina. En conclusión, las biopsias destinadas al test rápido de ureasa fueron muestras apropiadas para la detección de la resistencia a claritromicina en pacientes infectados con H. pylori. Esto es especialmente útil en aquellos casos en los que el número o el tamaño de las muestras son limitados. Además, este es el primer reporte de estudio de resistencia a claritromicina (mediante técnicas moleculares), directamente de biopsias gástricas en nuestra región.

Usefulness of rapid urease test samples for molecular analysis of clarithromycin resistance in Helicobacter pylori.

Helicobacter pylori is a gastric pathogen that is widely recognized as a causative agent of gastric disease. Its eradication is variable, mainly due to increased resistance to clarithromycin. Our objective was: to evaluate (i) if the biopsy specimen used for the rapid urease test is a useful sample to detect resistance to clarithromycin by PCR-RFLP and (ii) the distribution of A2142G and A2143G point mutations in the 23S rRNA gene, in relation to virulence factors in our region. Gastric specimens were collected from adult dyspeptic patients (n=141) and H. pylori was investigated by the rapid urease test, histopathological analysis and PCR for the hsp60 gene. Clarithromycin resistance was detected by PCR-RFLP in 62 H. pylori (+) paired biopsy specimens submitted to molecular analysis and the rapid urease test. H. pylori virulence factors were analyzed by multiplex PCR using specific primers for the cagA, vacA and babA2 genes. Thirteen out of 62 strains (20.9%) were resistant to clarithromycin: 6/13 (46.2%) harbored the A2143G mutation whereas 7/13 (53.8%) carried the A2142G point mutation. vacA m1s1 was the most frequent genotype among the resistant strains. In conclusion, the biopsy specimens used for the rapid urease test were suitable samples for clarithromycin resistance detection in patients infected with H. pylori, which became especially useful in cases where the number or size of the biopsies is limited. In addition, this is the first report of a molecular analysis for clarithromycin resistance performed directly from gastric biopsies in our region.

[Esophageal papilloma: case report, molecular identification of human papillomavirus and literature review]. / Papiloma esofágico: descripción de un caso, identificación molecular del virus del papiloma humano y revisión de la literatura.

sophageal squamous papilloma is an uncommon, usually asymptomatic, benign tumor of the squamous epithelium consisting of a raised, sessile, small and round (smooth or rough) lesion. The prevalence is between 0.01 and 0.45% of cases, with a male/female ratio of 3:1. The etiology and pathogenesis appear to be a mechanical or chemical irritation of the mucosa in addition to the presence of human papillomavirus (HPV), important agent in the evolution to a squamous carcinoma, especially HPV types 16 and 18. In this paper, we describe a case of esophageal papilloma whose diagnosis involved endoscopic images, pathological studies and detection of viral DNA by polymerase chain reaction. By using molecular techniques (PCR-RFLP) a profile consistent with HPV type 16 has been obtained. The patient underwent polypectomy and currently, after 3 years of diagnosis, he remains asymptomatic. This work is one of the first national reports of a patient with esophageal papilloma in which one of the most frequently HPV genotypes associated with esophageal carcinoma (HPV 16) has been detected.

[Multiplex PCR strategy for the simultaneous identification of Staphylococcus aureus and detection of staphylococcal enterotoxins in isolates from food poisoning outbreaks]. / Estrategia de PCR múltiple para la caracterización molecular simultánea de Staphylococcus aureus y enterotoxinas estafilocócicas en aislamientos de brotes de origen alimentario.

INTRODUCTION: Staphylococcal food poisoning is the most frequent type of food poisoning around the world. Staphylococcus aureus enterotoxins cause significant loss of water in the intestinal lumen, followed by vomiting and diarrhea. OBJECTIVE: To report a fast, reliable and inexpensive strategy based on multiplex PCR for the simultaneous identification of S. aureus and detection of five classical S. aureus enterotoxin genes ( sea, seb, sec, sed, see ) in Staphylococcus spp. strains isolated from food poisoning outbreaks. MATERIALS AND METHODS: We analyzed isolates from 12 food poisoning outbreaks occurred in Santa Fe province (Argentina). Isolation and phenotypic characterization were carried out by standard procedures. Genotypic analysis was performed by multiplex PCR, using primers for nuc , sea-see and 16S rRNA genes simultaneously. RESULTS: Of all the strains tested, 58% were found to carry toxigenic genes. Sea and seb toxins were found at the same percentage (29%) while sec, sed and see genes were found in a lower and identical proportion (14%). We did not find more than one different type of S. aureus enterotoxin in the isolates analyzed. CONCLUSIONS: The multiplex PCR strategy designed in this work has enabled us to identify strains of S. aureus and detect -at the same time- their enterotoxigenic ability. At present, our efforts are devoted to the detection of genes encoding enterotoxins other than the classical ones, in order to know their impact on staphylococcal food poisoning, as well as to investigate their relevance to our country's public health.

[Molecular detection and genotypification of Helicobacter pylori in gastric biopsies from symptomatic adult patients in Santa Fe, Argentina]. / Detección molecular y genotipificación de Helicobacter pylori en biopsias gástricas de pacientes adultos sintomáticos de la ciudad de Santa Fe, Argentina.

Our goals were: a) to detect Helicobacter pylori in gastric biopsies of symptomatic adults by PCR, b) to detect the presence of the cagA gene as well as of the allelic variants of the vacA gene, and c) to correlate genotypes with the endoscopic diagnoses. H. pylori was detected in 81 % (39/48) of patients by nested PCR for hsp60. The presence of cagA was detected in 15/22 of samples and vacA s1 - m1 was the most frequent allelic combination (15/22). Gastritis, the most frequent diagnosis, was associated with genotype cagA+ in 10/13 of patients. In this group, 9/13 showed the allelic variant vacA s1- m1. The variant vacA s2 - m2 was detected in 3/3 of gastritis cases by H. pylori with the cagA- genotype. These results are the first reported in our region and provide data of epidemiological interest.

Detección molecular y genotipificación de Helicobacter pylori en biopsias gástricas de pacientes adultos sintomáticos de la ciudad de Santa Fe, Argentina / [Molecular detection and genotypification of Helicobacter pylori in gastric biopsies from symptomatic adult patients in Santa Fe, Argentina].

Our goals were: a) to detect Helicobacter pylori in gastric biopsies of symptomatic adults by PCR, b) to detect the presence of the cagA gene as well as of the allelic variants of the vacA gene, and c) to correlate genotypes with the endoscopic diagnoses. H. pylori was detected in 81

(39/48) of patients by nested PCR for hsp60. The presence of cagA was detected in 15/22 of samples and vacA s1 - m1 was the most frequent allelic combination (15/22). Gastritis, the most frequent diagnosis, was associated with genotype cagA+ in 10/13 of patients. In this group, 9/13 showed the allelic variant vacA s1- m1. The variant vacA s2 - m2 was detected in 3/3 of gastritis cases by H. pylori with the cagA- genotype. These results are the first reported in our region and provide data of epidemiological interest.

Detección molecular y genotipificación de Helicobacter pylori en biopsias gástricas de pacientes adultos sintomáticos de la ciudad de Santa Fe, Argentina. / [Molecular detection and genotypification of Helicobacter pylori in gastric biopsies from symptomatic adult patients in Santa Fe, Argentina].

Our goals were: a) to detect Helicobacter pylori in gastric biopsies of symptomatic adults by PCR, b) to detect the presence of the cagA gene as well as of the allelic variants of the vacA gene, and c) to correlate genotypes with the endoscopic diagnoses. H. pylori was detected in 81

(39/48) of patients by nested PCR for hsp60. The presence of cagA was detected in 15/22 of samples and vacA s1 - m1 was the most frequent allelic combination (15/22). Gastritis, the most frequent diagnosis, was associated with genotype cagA+ in 10/13 of patients. In this group, 9/13 showed the allelic variant vacA s1- m1. The variant vacA s2 - m2 was detected in 3/3 of gastritis cases by H. pylori with the cagA- genotype. These results are the first reported in our region and provide data of epidemiological interest.

Papiloma esofágico: descripción de un caso, identificación molecular del virus del papiloma humano y revisión de la literatura. / [Esophageal papilloma: case report, molecular identification of human papillomavirus and literature review].

sophageal squamous papilloma is an uncommon, usually asymptomatic, benign tumor of the squamous epithelium consisting of a raised, sessile, small and round (smooth or rough) lesion. The prevalence is between 0.01 and 0.45

of cases, with a male/female ratio of 3:1. The etiology and pathogenesis appear to be a mechanical or chemical irritation of the mucosa in addition to the presence of human papillomavirus (HPV), important agent in the evolution to a squamous carcinoma, especially HPV types 16 and 18. In this paper, we describe a case of esophageal papilloma whose diagnosis involved endoscopic images, pathological studies and detection of viral DNA by polymerase chain reaction. By using molecular techniques (PCR-RFLP) a profile consistent with HPV type 16 has been obtained. The patient underwent polypectomy and currently, after 3 years of diagnosis, he remains asymptomatic. This work is one of the first national reports of a patient with esophageal papilloma in which one of the most frequently HPV genotypes associated with esophageal carcinoma (HPV 16) has been detected.

Papiloma esofágico: descripción de un caso, identificación molecular del virus del papiloma humano y revisión de la literatura / [Esophageal papilloma: case report, molecular identification of human papillomavirus and literature review].

sophageal squamous papilloma is an uncommon, usually asymptomatic, benign tumor of the squamous epithelium consisting of a raised, sessile, small and round (smooth or rough) lesion. The prevalence is between 0.01 and 0.45

of cases, with a male/female ratio of 3:1. The etiology and pathogenesis appear to be a mechanical or chemical irritation of the mucosa in addition to the presence of human papillomavirus (HPV), important agent in the evolution to a squamous carcinoma, especially HPV types 16 and 18. In this paper, we describe a case of esophageal papilloma whose diagnosis involved endoscopic images, pathological studies and detection of viral DNA by polymerase chain reaction. By using molecular techniques (PCR-RFLP) a profile consistent with HPV type 16 has been obtained. The patient underwent polypectomy and currently, after 3 years of diagnosis, he remains asymptomatic. This work is one of the first national reports of a patient with esophageal papilloma in which one of the most frequently HPV genotypes associated with esophageal carcinoma (HPV 16) has been detected.

[Description of a staphylococcal alimentary poisoning outbreak in Las Rosas, Santa Fe Province, Argentina]. / Descripción de un brote de intoxicación alimentaria estafilocócica ocurrido en Las Rosas, Provincia de Santa Fe, Argentina.

On February 2008, a suspected foodborne outbreak was reported in Las Rosas (Santa Fe Province, Argentina). The formal procedures indicated that an undetermined number of individuals had experienced food poisoning following consumption of vegetable cannelloni bought at a local shop. The manufacturer establishment was audited. Samples from the suspected food, as well as environmental samples and swabs from food handlers were obtained and involved subjects were interviewed. Remnants of ingested food were also obtained. Routine microbiological procedures of the foodborne outbreak revealed the presence of coagulase positive S. aureus subspecies aureus in samples from ingested and raw food, and from manipulators. Indicator microorganisms did not show significant levels and no other foodborne pathogen was isolated. Presence of staphylococcal enterotoxin-producing genes was subsequently investigated, and a positive result for enterotoxin B was shown in S. aureus strains isolated from a food handler as well as from food linked to the outbreak Moreover, these isolates showed 100% similarity by SmaI-PFGE. Timely notification together with coordinated sanitary measures and the availability of appropriate laboratory tools allowed to interrupt the chain of disease transmission by identifying risk and protective factors.

[Gastrointestinal Kaposi's sarcoma associated to AIDS. Case report]. / Sarcoma de Kaposi gastrointestinal asociado a síndrome de inmunodeficiencia adquirida. Descripción de un caso.

In this paper, we describe a particular clinical case of gastrointestinal Kaposi's sarcoma associated with acquired immunodeficiency syndrome in a 51-year-old female patient who survived 6 years without anti-retroviral treatment after the diagnosis of HIV infection. The patient was admitted to our hospital with fever, skin lesions in both upper limbs and thighs (one day of evolution) and dry cough (about a month of evolution). She was admitted to the General Internal Medicine Service for control, diagnosis and treatment. An upper digestive bleeding was detected there. Once referred to our Gastroenterology Service, an appropriate selection of tests (anamnesis, gastric video endoscopy, histology) was carried out. In the upper gastric video endoscopy, several epithelial lesions were observed and a presumptive diagnosis of Kaposi's sarcoma was obtained. The diagnosis was finally confirmed by chain polymerase reaction (PCR) amplifcation of HHV8 DNA. This finding highlights the contribution of the molecular biology laboratory that allowed in this case the first molecular identification in our institution of the causative agent of Kaposi's syndrome with gastrointestinal manifestations.

[Pneumococcal surface protein A (PspA) families. Relation with serotypes and clinical site of infection]. / Familias de la proteína de superficie PspA de Streptococcus pneumoniae. Relación con serotipos y localización.

PspA, a pneumococcal surface protein, is highly immunogenic and common to all serotypes. Although pspA gene shows a great heterogeneity at the N-terminal region, PspA protein has conserved epytopes which are able to elicit protective cross-reaction against various serotypes presenting different PspA. In spite of the high polimorfism of the PspA, three majority families can be identified. These properties convert PspA as ideal candidate for the formulation of a pneumococcal vaccine. Investigations of the PspA families were mostly carried out on prevalent serotypes in other countries. The aim of this study was to identify PspA families from Streptococcus pneumoniae isolates of our region as well as to associate them to prevalent serotypes or pathologies. We studied 70 isolates from pediatric patients with invasive infections. PCR was performed using specific primers for each family. In these studies we observed that 60% were PspA family 1, 34% were PspA family 2 and 6% remained unclassified. Serotypes 1 and 5 presented only family 1; serotypes 14, 6B, 19F y 18C showed genes from both families. Family 1 was observed respectively in 60 y 50% of pneumonias and meningitis. The family 2 was identified in 33 and 50% of pneumonias and meningitis. This information about the PspA family distribution could become a valuable contribution to develop an effective regional vaccine using recombinant PspA as immunogen.

Co-expression of HoxA9 and bcr-abl genes in chronic myeloid leukemia.

We have analyzed the co-expression of the bcr-abl and HoxA9 genes in the follow-up of patients with chronic myeloid leukemia (CML). In the present work we measured the HoxA9 and bcr-abl gene expression in sequential samples. In all patients, bcr-abl and HoxA9 were expressed at detectable levels in every sample. When the results were expressed in relation to abl, two different situations were found: (a) patients clinically stable at second sampling, with low relative risk at diagnosis (low Sokal's score), did not show significant differences in both bcr-abl and HoxA9 levels in the sequential samples analyzed, and (b) patients with poor prognosis (showing intermediate or high Sokal's score at diagnosis) had increased expression of bcr-abl as well as HoxA9 genes (p < 0.05). Since HoxA9 gene expression remains at relatively constant levels throughout adult life, our results could reflect actual changes in the expression rate of this gene associated with bcr-abl during the progression of CML.

Evaluation of UV-C induced changes in Escherichia coli DNA using repetitive extragenic palindromic-polymerase chain reaction (REP-PCR).

Ultraviolet radiation is an efficient inactivation method for a broad range of bacteria, viruses and parasites. Inactivation of microorganisms by UV-B and UV-C radiation is driven through modifications in their genomic DNA, being the most stable DNA-lesions different kinds of pyrimidine dimers (PDs) (e.g., cyclobutane pyrimidine dimers (CPDs) and other photoproducts). Taking into account that these modifications inhibit the DNA polymerization in vivo as well as in vitro, in the present work the usefulness of the REP-PCR assay to detect UV-induced changes in the Escherichia coli DNA was evaluated. In vitro amplification of DNA extracted at different times after UV treatment showed a disappearance of amplicons of higher size as time of treatment increases. When the bacteria were let to progress through their dark repair process, modifications in the electrophoretic patterns by REP-PCR were observed again. Amplified bacterial DNA tended to recover the profile showed at the beginning of treatment. In addition, the reappearance of bands of higher molecular size was associated to an increase in their signal intensity probably due to a higher amplification rate. Results of REP-PCR were correlated to the colony-forming ability of E. coli. It was concluded that REP-PCR appears as a rapid, robust, useful complementary methodology to monitor the impact of UV irradiation--at a molecular level--on the inactivation and the mechanisms of repair, applicable on a broad spectrum of microorganisms.

HOXA9 gene expression in the chronic myeloid leukemia progression.

In the present work we study the HOXA9 expression in sequential samples of patients with CML using RT-PCR. To obtain a semi-quantitative value, the HOXA9 expression was referred to the ABL gene in the same sample. The relative HOXA9 expression was higher in patients in the accelerated phase of the disease (p<0.005). Interestingly, a patient with poorer prognosis (high Sokal's score), showing the highest HOXA9/ABL ratio, quickly entered a blast crisis and died 5 months later. These first results could be considered as an evidence of an actual biological phenomenon that could provide additional information about the HOXA9 role in the CML progression.

Estudio comparativo de dos métodos para medición de hierro sérico / Comparative study of two methods for serum iron

El objetivo del presente trabajo fue comparar dos métodos colorimétricos comerciales, realizados en forma manual, para la determinación de hierro sérico; uno (el método comparativo) utiliza betafenantrolina como reactivo de color y otro (el método en comparación), usa ferrozine para el mismo propósito. Se procesaron 64 sueros de diferentes pacientes, siguiendo las recomendaciones para validación de métodos dadas por el National Committee for Clinical Laboratory Standards. Las concentraciones cubrieron todo el rango de interés clínico (rango 0,63-38,31 Amol/l / 3,5-214 Ag por ciento), y representaron el espectro de valores esperados en la aplicación clínica de rutina. Los métodos demostraron buena correlación (r = 0,96 p<0,0001). Se observó un buen acuerdo entre ambos obteniéndose, a partir del gráfico de Bland-Altman, en el rango de concentración de hierro útil para propósitos de diagnóstico clínico (0,63-10,74 Amol/L) una desviación relativa del 11,21 por ciento. A partir de este análisis se concluyó que las diferencias entre los dos métodos son aceptables y que ambos podrían intercambiarse, remarcándose importantes ventajas de índole práctica que tiene el método en comparación tales como utilización de menor volumen de muestra y menor tiempo de reacción (AU)

Estudio comparativo de dos métodos para medición de hierro sérico / Comparative study of two methods for serum iron

El objetivo del presente trabajo fue comparar dos métodos colorimétricos comerciales, realizados en forma manual, para la determinación de hierro sérico; uno (el método comparativo) utiliza betafenantrolina como reactivo de color y otro (el método en comparación), usa ferrozine para el mismo propósito. Se procesaron 64 sueros de diferentes pacientes, siguiendo las recomendaciones para validación de métodos dadas por el National Committee for Clinical Laboratory Standards. Las concentraciones cubrieron todo el rango de interés clínico (rango 0,63-38,31 µmol/l / 3,5-214 µg por ciento), y representaron el espectro de valores esperados en la aplicación clínica de rutina. Los métodos demostraron buena correlación (r = 0,96 p<0,0001). Se observó un buen acuerdo entre ambos obteniéndose, a partir del gráfico de Bland-Altman, en el rango de concentración de hierro útil para propósitos de diagnóstico clínico (0,63-10,74 µmol/L) una desviación relativa del 11,21 por ciento. A partir de este análisis se concluyó que las diferencias entre los dos métodos son aceptables y que ambos podrían intercambiarse, remarcándose importantes ventajas de índole práctica que tiene el método en comparación tales como utilización de menor volumen de muestra y menor tiempo de reacción