Mental health and academic performance in a cohort of first year primary school children in Chile

Introduction

Psychiatric disorders are common in children, and academic attainment is lower in children with psychiatric disorders. There are few data about the occurrence of mental health problems and the academic attainment among children in Chile.

Objectives

To determine the occurrence of mental health problems and its association with academic attainment in first-year students of elementary schools in Chile

Methods

The study was conducted in 39 urban and rural public elementary schools in Chile in 2019. The academic performance was measured using the Woodcock Muñoz IV Battery and the Corsi Bock-Tapping test. Mental health was assessed using the self-report Dominique Interactive and Strengths in children and Difficulties Questionnaire (SDQ) instruments in their parents and teachers. A triangulation of information was conducted between different informants.

Results

Overall 610 children were included in the analysis (mean age 7.10 years (SD=0.58), 51% women, 36% from rural area). A higher score in mathematics and reading was negatively correlated to a higher score in emotional symptoms, hyperactivity and peer relationship difficulties, separately, based on both teacher- and parent-reported SDQ. The correlation coefficient between reading scores with Dominique Interactive and Strengths externalizing symptoms was -0.22 (p<0,05). A higher maternal education level was associated with higher education attainment in their children (p <0,05). There was no association between rurality and children’s mental health symptoms.

Conclusions

The current results can inform local stakeholders in Chile about the importance of mental health at a very early age.

Disclosure

No significant relationships.

Experimental transmission of Caligus rogercresseyi between two different fish species

Caligus rogercresseyi is the dominant sea louse parasite affecting the salmon and trout industry in southern Chile. This parasite has a wide range of native and endemic fish hosts. The Patagonian blenny Eleginops maclovinus, which is parasitized mostly by the caligid species Lepeophtheirus spp. and C. rogercresseyi, is presumably responsible for the transmission of C. rogercresseyi to salmonids. The aim of this study was to characterize the transmission of parasites between different fish species and parasite cohort development under laboratory conditions. Parasite abundances and intensities were quantified. Transmission of parasites from Patagonian blenny to Atlantic salmon Salmo salar was lower (~9%, mainly corresponding to C. rogercresseyi) than from salmon to Patagonian blenny (14.7-26.9%, where only C. rogercresseyi were observed). This suggests that the transmission of C. rogercresseyi from salmon individuals is higher than the transmission from a native fish. Parasite cohorts developed successfully on both fish species, but apparently under different developmental rates. Water temperature, oxygen, and juvenile abundances were the variables that better explained cohort development success and variation in C. rogercresseyi adult abundances over time.

Computer Vision System for Welding Inspection of Liquefied Petroleum Gas Pressure Vessels Based on Combined Digital Image Processing and Deep Learning Techniques

One of the most important operations during the manufacturing process of a pressure vessel is welding. The result of this operation has a great impact on the vessel integrity; thus, welding inspection procedures must detect defects that could lead to an accident. This paper introduces a computer vision system based on structured light for welding inspection of liquefied petroleum gas (LPG) pressure vessels by using combined digital image processing and deep learning techniques. The inspection procedure applied prior to the welding operation was based on a convolutional neural network (CNN), and it correctly detected the misalignment of the parts to be welded in 97.7% of the cases during the method testing. The post-welding inspection procedure was based on a laser triangulation method, and it estimated the weld bead height and width, with average relative errors of 2.7% and 3.4%, respectively, during the method testing. This post-welding inspection procedure allows us to detect geometrical nonconformities that compromise the weld bead integrity. By using this system, the quality index of the process was improved from 95.0% to 99.5% during practical validation in an industrial environment, demonstrating its robustness.

Treatment, outcomes and costs of asthma exacerbations in Chilean children: a prospective multicenter observational study

OBJECTIVE

To describe potential regional variations in therapies for severe asthma exacerbations in Chilean children and estimate the associated health expenditures.

METHODS

Observational prospective cohort study in 14 hospitals over a one-year period. Children five years of age or older were eligible for inclusion. Days with oxygen supply and pharmacological treatments received were recorded from the clinical chart. A basic asthma hospitalization basket was defined in order to estimate the average hospitalization cost for a single patient. Six months after discharge, new visits to the Emergency Room (ER), use of systemic corticosteroids and adherence to the controller treatment were evaluated.

RESULTS

396 patients were enrolled. Patients from the public health system and from the north zone received significantly more days of oxygen, systemic corticosteroids and antibiotics. Great heterogeneity in antibiotic use among the participating hospitals was found, from 0 to 92.3% (ICC 0.34, 95% CI 0.16-0.52). The use of aminophylline, magnesium sulfate and ketamine varied from 0 to 36.4% between the different Pediatric Intensive Care Units (ICC 0.353, 95% CI 0.010-0.608). The average cost per inpatient was of $1910 USD. 290 patients (73.2%) completed the follow-up six months after discharge. 76 patients (26.2%) were not receiving any controller treatment and nearly a fourth had new ER visits and use of systemic corticosteroids due to new asthma exacerbations.

CONCLUSIONS

Considerable practice variation in asthma exacerbations treatment was found among the participating hospitals, highlighting the poor outcome of many patients after hospital discharge, with an important health cost.

Building a network for multicenter, prospective research of central nervous system infections in South America: Process and lessons learned

Multicenter collaborative networks are essential for advancing research and improving clinical care for a variety of conditions. Research networks are particularly important for central nervous system infections, which remain difficult to study due to their sporadic occurrence and requirement for collection and testing of cerebrospinal fluid. Establishment of long-term research networks in resource-limited areas also facilitates diagnostic capacity building, surveillance for emerging pathogens, and provision of appropriate treatment where needed. We review our experience developing a research network for encephalitis among twelve hospitals in five Peruvian cities since 2009. We provide practical suggestions to aid other groups interested in advancing research on central nervous system infections in resource-limited areas.

Hospitalizations for asthma exacerbation in Chilean children: A multicenter observational study

BACKGROUND

Asthma hospitalization rates in Chilean children have increased in the last 14 years, but little is known about the factors associated with this.

OBJECTIVE

Describe clinical characteristics of children hospitalized for asthma exacerbation.

METHODS

Observational prospective cohort study in 14 hospitals. Over a one-year period, children five years of age or older hospitalized with asthma exacerbation were eligible for inclusion. Parents completed an online questionnaire with questions on demographic information, about asthma, indoor environmental contaminant exposure, comorbidities and beliefs about disease and treatment. Disease control was assessed by the Asthma Control Test. Inhalation technique was observed using a checklist.

RESULTS

396 patients were enrolled. 168 children did not have an established diagnosis of asthma. Only 188 used at least one controller treatment at the time of hospitalization. 208 parents said they believed their child had asthma only when they had an exacerbation and 97 correctly identified inhaled corticosteroids as anti-inflammatory treatment. 342 patients used the wrong spacer and 73 correctly performed all steps of the checklist.

CONCLUSIONS

Almost half of the patients were not diagnosed with asthma at the time of hospitalization despite having a medical history suggestive of the disease. In the remaining patients with an established diagnosis of asthma potentially modifiable factors like bad adherence to treatment and poor inhalation technique were found. Implementing a nationwide asthma program including continued medical education for the correct diagnosis and follow up of these patients and asthma education for patients and caregivers is needed to reduce asthma hospitalization rates in Chilean children.

Virulence profile of Escherichia coli O157 strains isolated from surface water in cattle breeding areas

Shiga toxin-producing Escherichia coli (STEC) O157:H7 is a worldwide concern. Cattle are their main reservoir and may contaminate watercourses through manure. We characterized a collection of 38 STEC O157:H7 strains isolated from surface water in feedlots areas (puddles inside pens formed after the rainfall or by spill around drinking troughs, and small water courses and lagoons, formed by runoff). Nineteen (50·0%) strains harboured stx_2a /stx_2c genes, 18 (47·4%) stx_2c and one stx_1a /stx_2c . All strains harboured eae, ehxA, rfb_O157 and fliC_H7 genes, and the putative virulence determinants ECSP_0242, ECSP_2687 and ECSP_3620. All isolates tested as Lineage I/II by lineage-specific polymorphism assay-6. Nineteen (50%) belonged to the high virulent clade 8. The q₂₁ allele was found in all strains and q₉₃₃ /q₂₁ alleles in 17 (44·7%). By XbaI-pulsed-field gel electrophoresis, 29 strains were grouped into seven clusters. Four clusters grouped isolates from distant places separated by 150-250 km. This may be related to vectors, like birds, involved in their spread. Otherwise, three clusters contained isolates recovered at same places with intervals of 1-9 months. This could be explained by the high environmental persistence of STEC O157:H7. These strains recovered from surface water showed similar genotypes to those found in the bovine reservoir and in human diseases, and could be linked to the high incidence of haemolytic uremic syndrome in Argentina.

SIGNIFICANCE AND IMPACT OF THE STUDY

The challenge for the growing global demand for food is to find sustained production strategies without collateral effects. Intensive livestock operations generate large volumes of manure that can contaminate a finite resource, the water. This study shows how water contaminated by confined feeding operations can transport dangerous pathogens and warns to pay more attention to control and sanitation systems to prevent this type of pollution.

Shiga toxin-producing Escherichia coli (STEC) O22:H8 isolated from cattle reduces E. coli O157:H7 adherence in vitro and in vivo

PROBLEM ADDRESSED

Shiga toxin-producing Escherichia coli (STEC) are a group of bacteria responsible for food-associated diseases. Clinical features include a wide range of symptoms such as diarrhea, hemorrhagic colitis and the hemolytic uremic syndrome (HUS), a life-threatening condition.

OBJECTIVE

Our group has observed that animals naturally colonized with STEC strains of unknown serotype were not efficiently colonized with E. coli O157:H7 after experimental infection. In order to assess the basis of the interference, three STEC strains were isolated from STEC persistently-colonized healthy cattle from a dairy farm in Buenos Aires, Argentina.

METHODS AND RESULTS

The three isolated strains are E. coli O22:H8 and carry the stx1 and stx2d genes. The activatable activity of Stx2d was demonstrated in vitro. The three strains carry the adhesins iha, ehaA and lpf_O113. E. coli O22:H8 formed stronger biofilms in abiotic surface than E. coli O157:H7 (eae+, stx2+) and displayed a more adherent phenotype in vitro towards HeLa cells. Furthermore, when both serotypes were cultured together O22:H8 could reduce O157:H7 adherence in vitro. When calves were intragastrically pre-challenged with 10⁸ CFU of a mixture of the three STEC strains and two days later challenged with the same dose of the strain E. coli O157:H7 438/99, the shedding of the pathogen was significantly reduced.

CONCLUSIONS

These results suggest that E. coli O22:H8, a serotype rarely associated with human illness, might compete with O157:H7 at the bovine recto-anal junction, making non-O157 carrying-calves less susceptible to O157:H7 colonization and shedding of the bacteria to the environment.

Genetic features of human and bovine Escherichia coli O157:H7 strains isolated in Argentina

Shiga toxin-producing Escherichia coli (STEC) are important food-borne pathogens associated with human diseases. In Argentina, O157:H7 is the dominant serotype in hemolytic uremic syndrome (HUS) cases. Previously, we have described the almost exclusive circulation of human E. coli O157 strains belonging to the hypervirulent clade 8 in Neuquén Province. The aim of the present study was to investigate, by a broad molecular characterization, if this particular distribution of E. coli O157 clades in Neuquén is similar to the situation in other regions of the country and if it may be originated in a similar profile in cattle, its main reservoir. Two-hundred and eighty O157 strains (54 bovine and 226 human) isolated between 2006 and 2008 in different regions of Argentina were studied. All strains harbored rfbO157, fliCH7, eae, and ehxA genes. The predominant genotype was stx2a/stx2c in human (76.1%) and bovine (55.5%) strains. All human isolates tested by Lineage-Specific Polymorphism Assay (LSPA-6), were lineage I/II; among bovine strains, 94.1% belonged to lineage I/II and 5.9% to lineage I. No LSPA-6 lineage II isolates were detected. Single nucleotide polymorphism (SNP) analysis has revealed the existence of nine clade phylogenetic groups. In our clinical strains collection, 87.6% belonged to the hypervirulent clade 8, and 12.4% were classified as clade 4/5. In bovine isolates, 59.3% strains were clade 8, 33.3% clade 4/5 and 7.4% clade 3. More than 80% of human strains showed the presence of 6 of the 7 virulence determinants described in the TW14359 O157 strain associated with the raw spinach outbreak in the U.S. in 2006. More than 80% of bovine strains showed the presence of 3 of these factors. The q933 allele, which has been related to high toxin production, was present in 98.2% of clinical strains and 75.9% of the bovine isolates. The molecular characterization of human STEC O157 strains allows us to conclude that the particular situation previously described for Neuquén Province, may actually be a characteristic of the whole country. These genetic features are quite similar to those observed in the bovine reservoir and may be derived from it. This data confirms that, unlike the rest of the world, in Argentina most of the STEC O157 strains present in cattle may cause human infections of varying severity and the marked virulence described for these strains may be related to the high incidence of HUS in our country.

Cu impedance-based detection of superparamagnetic nanoparticles

A novel method for superparamagnetic nanoparticle detection using copper impedance as the sensing property is presented. The increase of impedance produced by the proximity of the nanoparticles in the copper is comparable to that of classical magnetoimpeditive materials. A physical interpretation of the detection in terms of the induction of eddy currents in the copper element by the oscillating magnetic moments of the particles is proposed. Experimental research has been done to support this hypothesis, namely, analyses of the influence of the driving current frequency and amplitude, and of the geometry and size of the sensing conductor. The ability of copper to quantify the number of nanoparticles was successfully verified, evidencing the great potential of this new method.

Giant retroperitoneal sarcoma: case report

OBJECTIVE

To report a new case of giant retroperitoneal mass with silent beginning.

METHODS

We present the case of a 36 year old man with a giant retroperitoneal liposarcoma 35 × 15 cm in size. The only symptom was a one month history of minimal abdominal pain.

CONCLUSION

Liposarcoma is the most frequent retroperitoneal mass. In most of the cases clinical symptoms are silent, being this the reason why diagnosis is late and the size is large. The best image options are CT scan or MRI but final diagnosis is based on pathology results. Its treatment is surgery and relapse is very usual.

Genotypic characterization of non-O157 Shiga toxin-producing Escherichia coli in beef abattoirs of Argentina

The non-O157 Shiga toxin-producing Escherichia coli (STEC) contamination in carcasses and feces of 811 bovines in nine beef abattoirs from Argentina was analyzed during a period of 17 months. The feces of 181 (22.3%) bovines were positive for non-O157 STEC, while 73 (9.0%) of the carcasses showed non-O157 STEC contamination. Non-O157 STEC strains isolated from feces (227) and carcasses (80) were characterized. The main serotypes identified were O178:H19, O8:H19, O130:H11, and O113:H21, all of which have produced sporadic cases of hemolytic-uremic syndrome in Argentina and worldwide. Twenty-two (7.2%) strains carried a fully virulent stx/eae/ehxA genotype. Among them, strains of serotypes O103:[H2], O145:NM, and O111:NM represented 4.8% of the isolates. Xba I pulsed-field gel electrophoresis pattern analysis showed 234 different patterns, with 76 strains grouped in 30 clusters. Nine of the clusters grouped strains isolated from feces and from carcasses of the same or different bovines in a lot, while three clusters were comprised of strains distributed in more than one abattoir. Patterns AREXSX01.0157, AREXBX01.0015, and AREXPX01.0013 were identified as 100% compatible with the patterns of one strain isolated from a hemolytic-uremic syndrome case and two strains previously isolated from beef medallions, included in the Argentine PulseNet Database. In this survey, 4.8% (39 of 811) of the bovine carcasses appeared to be contaminated with nonO157 STEC strains potentially capable of producing sporadic human disease, and a lower proportion (0.25%) with strains able to produce outbreaks of severe disease.

Bacterial pathogens associated with bloody diarrhea in Uruguayan children

Diarrheal disease continues to be a serious health problem, especially in developing countries. Bloody diarrhea represents approximately 20-30% of all cases and has higher morbidity and mortality. Treatment with antibiotics is beneficial in cases of Shigella, Campylobacter, Yersinia and Salmonella infection, principally in those children with a higher risk of invasive disease. The aims of this study were to detect the bacterial agents associated with bloody diarrhea in children and to determine their antimicrobial susceptibility patterns. Between June 2001 and January 2008, 249 children with bloody diarrhea were studied. Shigella and Shiga toxin-producing Escherichia coli (STEC) were recovered from 48 (19.3%) and 3 (1.2%) of the total of cases, respectively. In 49 out of 249 children, in whom other enteropathogens were investigated, we recovered Campylobacter jejuni from 7 children (14.3%), Salmonella spp. from 2 (4.1%) and Aeromonas spp. from 1 (2%) in addition to Shigella from 7 children (14.3%). Thirty-four (70%) Shigella isolates showed resistance to ampicillin and 13 (27%) to trimethoprim-sulfamethoxazole. All Shigella isolates were susceptible to nalidixic acid, ciprofloxacin and ceftriaxone. Salmonella and STEC isolates were susceptible to all antibiotics assayed. Thus, the use of trimethoprim-sulfamethoxazole or ampicillin would not be appropriate for the empirical treatment of Shigella - associated diarrhea.

[Multiplex PCR for the detection of sea, seb, sec, sed and see genes of Staphylococcus aureus. Characterization of isolates from food]

Multiplex PCR for the detection of sea, seb, sec, sed and see genes of Staphylococcus aureus. Characterization of isolates from food. The presence of Staphylococcus aureus in food represents a potential risk to public health, being its enterotoxins the major virulence factor. Enterotoxin detection can be determined by ELISA, but only for the pool of enterotoxins SEA, SEB, SEC, SED and SEE. The main aims of this study were to optimize two PCR techniques for detection of S. aureus sea, seb, sec, sed and see, and to characterize Staphylococcus spp. isolates associated with food intoxication. Two PCR techniques were optimized and 115 Staphylococcus spp. isolates from Ciudad Aut6noma de Buenos Aires, and Buenos Aires, Córdoba, and Neuquén provinces were characterized. The characterization was performed by biochemical tests, ELISA and PCR. Sixty-eight isolates (59.1%) were positive by ELISA, while 61 (53%) were positive by PCR. Out of the positive PCR isolates, 34 (55.7%) carried the sea gene, 9 (14.8%) the seb gene, 5 (8.1%) the see gene, 4 (6.5%) the sec gene, 6 (9.9%) were positive for sea and seb genes, 2 (3.3%) for sea and sec genes, and 1 (1.7%) for sea and sedgenes. This is the first study of genotypic characterization of S. aureus isolates associated with food intoxication from different provinces of Argentina.

Management in the emergency room of patients requiring hospital treatment of community-acquired pneumonia

INTRODUCTION

To identify factors influencing decisions in initial management of community-acquired pneumonia (CAP) admitted to hospital through Emergency departments.

METHODS

Records of CAP adult patients admitted to 24 Spanish hospitals in January-March 2003 were reviewed. Patients sent for ambulatory treatment were excluded.

RESULTS

341 patients (67.0 +/- 24.6 years; 65.3% males) were included; 39% were taking antibiotics at attendance. PSI was (% patients): I-II (19.7%), III (14.7%), and IV-V (65.6%). Comorbidities were: COPD (37.2%), heart disease (24.6%), hypertension (17%), diabetes mellitus (10.8%), and malignancies (10%). Pneumococcal/Legionella urinary antigens were performed in 34.0%/42.2% patients. Fewer (p < or = 0.006) rapid tests were performed in class IV-V (p = 0.001), with higher (p < or = 0.01) pneumococcal positive results in class V. Initial treatment was fluoroquinolone (37.5%), beta-lactam + macrolide (26.4%), beta-lactam (22.9%), macrolide (4.7%), and others (8.5%). Patients referred to Internal Medicine had higher heart disease (p = 0.06) and hypertension (p = 0.001) as comorbidity than those at Short-Stay Units or Pneumology. COPD patients were equally distributed between Internal Medicine and Pneumology, with differences vs. Short-Stay Units.

CONCLUSIONS

Rapid diagnostic tests were underused, maybe due to broad empirical treatments covering drug-resistant pneumococci and L. pneumophila (regardless PSI and comorbidity). Presence of comorbidities or positive results in rapid diagnostic tests seems to influence the medical ward to which the patient is referred to, but not initial treatment.

[Foodborne disease outbreak in El Huecú community, province of Neuquén]

In the summer of 2006, an epidemic outbreak of acute gastrointestinal illness related to food consumption occurred in a small town in the province of Neuquén, Argentina. During a popular feast, approximately 800 local residents attended lunch held in the facilities of the Municipal Gymnasium. About three hours later, nearly 150 attendees sought medical assistance at the local hospital due to acute gastroenteritis. A case-control epidemiological investigation was conducted using representative non-probability sampling. The epidemiological investigation showed a common-source foodborne disease outbreak with a case-control ratio of 1:1.8. The main symptoms were abdominal cramps (88%), vomiting (73.5%) and diarrhea (60%). The cake was identified as the source of infection (OR 9.79; IC 95%, 2.66-36.00; p = 0.0001), and unsatisfactory hygienic conditions in food production, conservation and handling steps were identified. Coagulase positive, enterotoxigenic Staphylococcus aureus, subspecies aureus was detected in a piece of cake, with a count of 2.4 x 10(6) CFU/g, and in samples from the hands and nostrils of three people involved in food preparation and service. The strains isolated from both the cake and one of the food handlers carried the sea gene, and presented the same Smal-PFGE pattern. The foodborne disease outbreak was considered to be due to contamination in the preparation process of the cake consumed at the feast, which was related to inadequate hygienic conditions, lack of refrigeration and cold chain disruption.

Renal damage and death in weaned mice after oral infection with Shiga toxin 2-producing Escherichia coli strains

Enterohaemorrhagic Escherichia coli (EHEC) O157:H7 infections are considered a public health problem in both developed and developing countries because of their increasing incidence and the severity of clinical presentation. Approximately 10% of infected patients develop complications such as haemolytic uraemic syndrome (HUS) characterized by acute renal failure, thrombocytopenia and haemolytic anaemia. The precise sequence of events leading to HUS is still understood incompletely. Because of the lack of a reproducible small animal model for EHEC infections, in vivo studies examining EHEC-host early interactions are limited and insufficient. The aim of this study was to characterize the weaned BALB/c mouse as a model of E. coli O157:H7 infection. In this paper we report that human Shiga toxin 2 (Stx2)-producing EHEC strains can adhere to the intestinal epithelium of weaned BALB/c mice, and produce local damage which leads to systemic disease and death in a percentage of infected mice. The lethality of the EHEC strain is closely age-dependent, and is related to the bacterial ability to colonize intestine and to produce Stx2. It can be concluded that the weaned BALB/c mouse can be used as a small animal model to study host early responses, and the role of bacterial pathogenic factors in the induction of systemic disease, thus providing a useful tool for the evaluation of therapeutic or vaccine approaches.

[Detection and characterization of Shiga toxin-producing Escherichia coli from clinical cases and food in Uruguay]

We have assessed the frequency of Shiga toxin-producing Escherichia coil (STEC) in clinical and food samples as well as studied the genotypic and phenotypic characteristics of the recovered strains. One hundred ninety eight fecal samples from children with bloody diarrhea (BD), 14 from children with hemolytic uremic syndrome (HUS), 220 ground beef samples and 4 STEC isolates from other beef-derived products were analyzed. The STEC strains were isolated from 3 (1.5%) children with bloody diarrhea, 1 (7%) from a child with HUS and 4 (1.8%) from ground beef samples. All strains were eae and ehxA positive. The serotypes found were: O157:H7 (9 strains), O26:H11 (2), O111: NM (1) and O145:HNT (1). All O157:H7 STEC strains harbored the eae subtype gamma1, O26:H11 and O145:HNT strains, subtype beta1 and O111:NM strain, subtype gamma2/theta. The STEC strains of the same serogroup showed high genetic diversity. In Uruguay, STEC is not frequently isolated from cases of bloody diarrhea in children. However, all the recovered STEC strains carried the genes associated with severe disease and 2 out of 3 children infected with STEC developed HUS. Ground beef and other food products might be important vehicles for O157:H7 strains.

[In silico analysis of the capability of two polimerase chain reaction techniques for stx gene detection]

Shiga toxin-producing Escherichia coli is an emergent pathogen, being the Shiga toxin (Stx) the main virulence factor. These toxins are classified into 6 types (1,2, 2c, 2d, 2e and 2f) and 22 variants. In Argentina, two PCR for stx gene detection, PCR-MK and multiplex-PCR, were validated. The aim of this work was to analyze, by using bioinformatic tools, the stx variants that could be amplified by these PCRs, and to experimentally show the amplification of 8 stx variants. Twenty-five nucleotide sequences were collected from GenBank corresponding to 21 stx variants. The BLAST 2 sequences program was used to analyze the complementarities between the nucleotide sequence of the variants and the primers corresponding to the PCR studied. PCR-MK could detect types stx1, stx2, stx2c, stx2d and stx2f, but not type stx2e and three type stx2c variants. On the other hand, the multiplex-PCR could detect types stx1, stx2, stx2c, stx2d, but not stx2e and stx2f types. It was experimentally determined that both PCRs can detect those variants that cause severe disease in humans.

Thyroid hormones, learning and memory

Thyroid hormones (THs), T3 and T4, have many physiological actions and are essential for normal behavioral, intellectual and neurological development. THs have a broad spectrum of effects on the developing brain and mediate important effects within the CNS throughout life. Insufficient maternal iodine intake during gestation and TH deficiency during human development are associated to pathological alterations such as cretinism and mental retardation. In adulthood, thyroid dysfunction is related to neurological and behavioral abnormalities, including memory impairment. Analysis of different experimental models suggests that most of the effects on cognition as a result of thyroid dysfunction rely on hippocampal modifications. Insufficiency of THs during development thus alters hippocampal synaptic function and impairs behavioral performance of hippocampal-dependent learning and memory tasks that persist in euthyroid adult animals. In the present review, we summarize the current knowledge obtained by clinical observations and experimental models that shows the importance of THs in learning and mnemonic processes.

Prolonged fecal shedding of Shiga toxin-producing Escherichia coli among children attending day-care centers in Argentina

In this report we describe the detection and duration of fecal shedding of Shiga toxin-producing Escherichia coil (STEC) O157 and non-O157 in symptomatic and asymptomatic cases during four events occurred among children in day-care centers in Argentina. In each event, the cases were identified among children, family contacts and staff members of the Institution. The isolates were characterized by pheno-genotyping and subtyping methods. The STEC fecal shedding was prolonged and intermittent. Strains O157:H7 (1st event); O26:H11 (2nd event); O26:H11 (3rd event) and O145:NM (4th event) were shed during 23-30, 37, 31 and 19 days, respectively. Considering the possibility of STEC intermittent long-term shedding, symptomatic and asymptomatic individuals should be excluded from the Institution until two consecutive stool cultures obtained at least 48 h apart, test negative.

[Isolation, characterization and typing of Escherichia coil 0157:H7 strains from beef products and milk]

Shiga toxin (Stx)-producing Escherichia coli (STEC) is an emergent pathogen associated with foodborne diseases, especially foodstuffs of animal origin. A total of 250 beef samples (ground beef and hamburgers) obtained from retail outlets in Santa Fe and Santo Tomé cities, and 150 milk samples from bulk tank milk from dairy barns of the region were analyzed by selective enrichment and immunomagnetic separation. Escherichia coli O157:H7 stx2, eae and ehxA positive strains were isolated from three (1.2%) beef samples. The strains could be differentiated by pulsed-field gel electrophoresis, phagetyping and genotyping of stx. The milk samples were negative for STEC O157. These findings confirm the role of food of animal origin in the epidemiology of E. coli O157:H7 - associated diseases.

[Evaluation of two techniques of molecular subtyping to study Pasteurella multocida]

Typeability, reproducibility, and discriminatory power of ERIC-PCR and Apal-PFGE to establish the genetic relation of P. multocida strains were determined. Forty-nine strains of different source, biotype, capsular group, somatic serotype, and resistance to antimicrobials were studied. By ERIC-PCR, 31 patterns were defined with 10 to 14 bands in a rank of 0.2 and 1.2 kb. By Apal-PFGE, 37 restriction patterns were established with 7 to 15 bands of 34 to 450 kb. Typeability was 100% (T=1) for ERIC-PCR, and 94% (T = 0.94) for Apal-PFGE. Reproducibility of both techniques was 100% (R=1). Discriminatory power was 93% (D = 0.93) for ERIC-PCR, and 98% (D = 0.98) for Apal-PFGE. By using both techniques, epidemiologically related strains were grouped, and unrelated strains were clearly differentiated. The value of ERIC-PCR and Apal-PFGE as complements to epidemiologic studies was demonstrated, especially when both techniques were used to analyze the strains.

[Identification, biotypification and characterization of Pasteurella multocida strains isolated in Argentina]

Thirty Pasteurella multocida strains isolated in Argentina from human and animal samples were identified, biotypified and characterized. Twenty-two (73%) strains were identified as P. multocida subsp. multocida, 5 (17%) as P. multocida subsp. gallicida, and 3 (10%) as P. multocida subsp. septica. All strains were grouped in 8 biotypes, and 70% of the strains presented capsular type A. The most frequent somatic serotypes were 1 (n:11) and 3 (n:9). P. multocida strains from swine source were resistant to tiamulin, streptomycin and tetracycline. Characterization of P. multocida strains isolated in Argentina is the first step to conduct future studies intended for the prevention and treatment of pasteurellosis in human and veterinary medicine.

Characterization and epidemiologic subtyping of Shiga toxin-producing Escherichia coli strains isolated from hemolytic uremic syndrome and diarrhea cases in Argentina

Argentina has a high incidence of hemolytic uremic syndrome (HUS); 12.2 cases per 100,000 children younger than 5 years old were reported in 2002. Shiga toxin (Stx)-producing Escherichia coli (STEC) is the primary etiologic agent of HUS, and STEC O157 is the predominant serogroup isolated. The main objective of the present work was to establish the phenotypic and genotypic characteristics of the STEC strains in general isolated from Argentine children during a prospective study and the clonal relatedness of STEC O157:H7 strains using subtyping techniques. One hundred and three STEC strains isolated from 99 children were included. The phenotypic and genotypic features were established, and a polymerase chain reaction-restriction fragment length polymorphism (PCRRFLP) was performed to determine stx2 variants. The clonal relatedness of E. coli O157 isolates was established by phage typing and pulsed-field gel electrophoresis (PFGE). The 103 STEC strains belonged to 18 different serotypes, and 59% were of serotype O157:H7. Stx2 was identified in 90.3%, and stx1 in 9.7%. Among the 61 STEC O157 strains, 93.4% harbored the stx2/stx2vh-a genes; PT4 (39.3%) and PT2 (29.5%) were the predominant phage types. Using PFGE with the enzyme XbaI, a total of 41 patterns with at least 80% similarity were identified, and seven clusters with identical profiles were established. Some of the clusters were further split by PFGE using BlnI as the second enzyme. Isolates with indistinguishable PFGE patterns were with one exception also indistinguishable by phage typing and stx genotyping. These findings confirmed that some isolates were genetically related. However, no epidemiological linkages were identified. STEC strains with different genotypes and belonging to diverse serotypes were isolated in Argentina. Some STEC O157 strains could not be distinguished by applying subtyping techniques such as PFGE and phage typing.

OUTBREAKS OF AVIAN CHOLERA IN HOPE BAY, ANTARCTICA

During austral summers 1999-2000 and 2000-01, two outbreaks of avian cholera occurred in the Hope Bay area (63 degrees 24'S, 56 degrees 59'W), located on the tip of the Antarctic Peninsula. Eighty-six dead birds were found: five kelp gulls (Larus dominicanus), 36 skuas (Stercorarius sp.), and 45 Adelie penguins (Pygoscelis adeliae). The carcasses were studied using clinical, pathological, and microbiological criteria. Water samples from ponds where birds were settled and samples from 90 healthy birds also were analyzed during the second outbreak. Pasteurella multocida isolates were identified by biochemical tests, capsular type, somatic serotype, and susceptibility to nine antibiotics. Molecular subtyping was performed by ApaI and SmaI pulsed-field gel electrophoresis (PFGE) and enterobacterial repetitive intergenic consensus (ERIC-PCR). In February 2000, mortality in skuas was 16% and 2% in kelp gulls. In the 2000-01 breeding season, mortality in south polar skuas was 47%, 24% in brown skuas, 1.4% in kelp gulls, and 0.01% in Adelie penguins. All birds had lesions of avian cholera. In kelp gulls the presentation was chronic, whereas skuas and penguins suffered subacute and acute disease, respectively. Fifty-five isolates recovered from dead birds and one from water were identified as P. multocida gallicida, type A:1. The strains presented a unique molecular pattern by PFGE and ERIC-PCR. A possible hypothesis to explain the origin of the outbreaks was that nonbreeder kelp gulls carried P. multocida gallicida to Hope Bay, and avian cholera was transmitted through water to skuas and penguins. This study reports avian cholera in new bird species, their potential role in the transmission of the disease, and the different responses of these species to the disease.

[Isolation of Shiga-toxin-producing Escherichia coli strains during a gastrointestinal outbreak at a day care center in Mar del Plata City]

From October 15 to November 8, 2003, a gastrointestinal outbreak occurred at a day care center in a Hospital in Mar del Plata City. Fourteen out of 80 (17.5%) children, mean age 23.6 +/- 13.9 months, and the mother of one of them had diarrhea. One case developed hemolytic uremic syndrome. No conclusive evidence of the origin of the outbreak was found, but the epidemic curve suggested person-to-person spread. The usual practices at the place where infant milk formula was prepared at the day care center, together with the inadequate infrastructure conditions and hygiene practices at the kitchen of the hospital, were considered risk factors. One case had Shiga toxin-producing Escherichia coli (STEC) O103:H2 infection and other STEC O26:H11. The duration of shedding for the child with O26:H11 infection was 37 days. In the other symptomatic children, the pathogen was not recovered from fecal samples collected 6 or more days after the onset of the illness. This emphasizes that the collection of early samples is necessary to recover STEC strains. In order to prevent and control enteric diseases in day care facilities the following measures are necessary: optimal hygiene standards, early case reporting, and exclusion of those who remain culture-positive.

[Validation of a multiplex PCR for detection of Shiga toxin-producing Escherichia coli]

Shiga toxin-producing Escherichia coli (STEC) cause non-bloody or bloody diarrhea, hemorrhagic colitis and hemolytic uremic syndrome (HUS) in humans. The aim of the present study was to validate a multiplex PCR for the STEC diagnosis based on the detection of stx1, stx2 and rfbO157 genes. The multiplex PCR validation was carried out in two independent laboratories in a parallel way. Work range, selectivity and robustness were established. The PCR performance was evaluated using different concentrations of two STEC strains harboring different target genes. The work range depended on the strain analyzed, the maximum and the minimum values were 6.6 x 10(7) and 1.0 x 10(4) CFU/50 microl. The detection limit was 1.0 x 10(4) CFU/50 microl and the cut limit 1.0 x 10(5) CFU/50 ml. A good robustness was observed when different variables were introduced. Inclusivity, exclusivity, positive predictivity, negative predictivity and analytical accuracy were of 100%. Interference was not shown when different concentrations of STEC strains, carrying different genes, were used. The validated technique is an appropriate alternative for detection and confirmation of STEC O157 and non-O157 strains from bacterial cultures.

Mutation at position -132 in the islet amyloid polypeptide ( IAPP) gene promoter enhances basal transcriptional activity through a new CRE-like binding site

AIMS/HYPOTHESIS

Mutations in the islet amyloid polypeptide ( IAPP) gene may play a potential role in the abnormal regulation or expression of the peptide. The aim of this study was to determine the functional role of the -132 G/A mutation reported in the promoter region of the IAPP gene in a population of Spanish Type 2 diabetic patients.

METHODS

We investigated the transcriptional activity using MIN6 cells and luciferase reporter plasmids in several culture conditions. Key regulatory elements of the IAPP promoter region were also analysed by electrophoretic mobility shift assays (EMSA).

RESULTS

The mutant construct doubled IAPP transcriptional activity ( p<0.001). Both constructs showed severely reduced promoter activity (four-fold decrease) in the presence of verapamil and diazoxide. In contrast, IAPP promoter activity was doubled after incubation with forskolin or dexamethasone, regardless of the glucose concentrations in the culture media. EMSA revealed that the -132 G/A mutation increased the binding affinity through two DNA-protein complexes. In addition, a cAMP-responsive element binding protein (CREB) was identified by super-shift EMSA.

CONCLUSIONS/INTERPRETATION

Our studies show that the wild-type and the mutant constructs are regulated in a similar pattern under all conditions, strongly indicating that the -132 G/A mutation increases basal but not inducible transcription. These results may be explained by new binding to the mutant region through CREB and other transcription factors not yet identified.

Avian cholera in a southern giant petrel (Macronectes giganteus) from Antarctica

A southern giant petrel (Macronectes giganteus) was found dead at Potter Peninsula, King George Island, South Shetland, Antarctica. The adult male was discovered approximately 48 hr after death. Macroscopic and microscopic lesions were compatible with avian cholera and the bacterium Pasteurella multocida subsp. gallicida, serotype A1 was isolated from lung, heart, liver, pericardial sac, and air sacs. In addition, Escherichia coli was isolated from pericardial sac and air sacs. This is the first known report of avian cholera in a southern giant petrel in Antarctica.

Isolation and characterisation of Shiga toxin-producing Escherichia coli O157:H7 from calves in Argentina

Four hundred and twenty-two calves were examined for intestinal carriage of Shiga toxin-producing Escherichia coli O157:H7 using conventional plating. Two (0.5%) E. coli O157 were recovered. They were compared with 96 Argentine strains of different origin by pulsed-field gel electrophoresis, phage typing and PCR-RFLP of stx2 genes. One strain isolated from a calf, was closely related with 18 strains of clinical origin.

[Development and application of a method for isolating Escherichia coli O157:H7 in the city of Gualeguaychú]

Culture media, reagents, and commercial kits were compared on artificially contaminated food samples. The objective was to find an isolation method for Escherichia coli O157:H7 sensitive, specific and accessible in terms of cost, requirements of equipments and qualification of the analyst. The adopted scheme consisted in a selective enrichment at 42 degrees C during 18 to 24 h, using an appropriate medium, in accordance with the nature of the sample, followed by a step of immunomagnetic separation and simultaneous isolation on a chromogenic agar and MacConkey sorbitol agar with potassium tellurite and cefixime, during 18-24 h at 37 degrees C. The presumptive colonies were confirmed as E. coli O157 by serological and biochemical tests. Secondly, this methodology was applied to food samples, water, bovine gastric content and manure. A total of 410 samples were studied: 279 from meat, 54 milk and dairy products, 6 from vegetables, 27 water samples and 44 bovine gastric content and manure. The frequency of isolation of E. coli O157:H7 was of 3.9%. The phenotypic and genotypic characterization of the isolates was performed. A simple isolation methodology for E. coli O157 was developed, which proved accessible to food laboratories of lower complexity. This methodology allowed the detection of this pathogen in food and environmental samples in Gualeguaychú City. The role of water as vehicle of infection was also established. The strains harbored the same virulence factors as those recovered from human disease.