Genomic epidemiology of third-generation cephalosporin-resistant Escherichia coli from Argentinian pig and dairy farms reveals animal-specific patterns of co-resistance and resistance mechanisms

Control measures are being introduced globally to reduce the prevalence of antibiotic resistance (ABR) in bacteria on farms. However, little is known about the current prevalence and molecular ecology of ABR in bacterial species with the potential to be key opportunistic human pathogens, such as Escherichia coli, on South American farms. Working with 30 dairy cattle farms and 40 pig farms across two provinces in central-eastern Argentina, we report a comprehensive genomic analysis of third-generation cephalosporin-resistant (3GC-R) E. coli, which were recovered from 34.8% (cattle) and 47.8% (pigs) of samples from fecally contaminated sites. Phylogenetic analysis revealed substantial diversity suggestive of long-term horizontal and vertical transmission of 3GC-R mechanisms. CTX-M-15 and CTX-M-2 were more often produced by isolates from dairy farms, while CTX-M-8 and CMY-2 and co-carriage of amoxicillin/clavulanate resistance and florfenicol resistance were more common in isolates from pig farms. This suggests different selective pressures for antibiotic use in these two animal types. We identified the β-lactamase gene blaROB, which has previously only been reported in the family Pasteurellaceae, in 3GC-R E. coli. blaROB was found alongside a novel florfenicol resistance gene, ydhC, also mobilized from a pig pathogen as part of a new composite transposon. As the first comprehensive genomic survey of 3GC-R E. coli in Argentina, these data set a baseline from which to measure the effects of interventions aimed at reducing on-farm ABR and provide an opportunity to investigate the zoonotic transmission of resistant bacteria in this region.

IMPORTANCE

Little is known about the ecology of critically important antibiotic resistance among bacteria with the potential to be opportunistic human pathogens (e.g., Escherichia coli) on South American farms. By studying 70 pig and dairy cattle farms in central-eastern Argentina, we identified that third-generation cephalosporin resistance (3GC-R) in E. coli was mediated by mechanisms seen more often in certain species and that 3GC-R pig E. coli were more likely to be co-resistant to florfenicol and amoxicillin/clavulanate. This suggests that on-farm antibiotic usage is key to selecting the types of E. coli present on these farms. 3GC-R E. coli and 3GC-R plasmids were diverse, suggestive of long-term circulation in this region. We identified the de novo mobilization of the resistance gene blaROB from pig pathogens into E. coli on a novel mobile genetic element, which shows the importance of surveying poorly studied regions for antibiotic resistance that might impact human health.

Ureaplasma diversum-Ureaplasma sp. alone or concomitantly with Mycoplasma hyopneumoniae in pig lungs with and without pneumonia: A descriptive exploratory study in abattoirs

Occurrence of Ureaplasma diversum (U. diversum) has been associated with reproductive failures in cattle and detected in pigs with and without pneumonia. However, its role in the porcine respiratory disease complex (PRDC) is unclear. A cross-sectional study was conducted in abattoirs, inspecting 280 pig lungs from eight herds. All the lungs were inspected, processed and classified according to the histopathological analysis. Moreover, bronchoalveolar lavage (BAL) specimens were collected and processed by PCR for detection of U. diversum and Mycoplasma hyopneumoniae (M. hyopneumoniae). Ureaplasma sp.-U. diversum and M. hyopneumoniae were detected in 17.1% and 29.3% of the analyzed BAL specimens, respectively. The concomitant presence of both microorganisms was detected in 12.5% of the inspected lungs. Both agents were found in lungs with and without pneumonia. M. hyopneumoniae was detected in 31.8% of pig lungs with enzootic pneumonia-like lesions, while Ureaplasma sp.-U. diversum was detected in 27.5% of lungs with these lesions. This descriptive exploratory study provides information for future experimental and field-based studies to better define the pathogenic role of this organism within the PRDC.

In-feed nutritional additive probiotic Saccharomyces boulardii RC009 can substitute for prophylactic antibiotics and improve the production and health of weaning pigs

Background and Aims

Non-therapeutic antibiotic use is associated with the current decrease in antibiotic therapeutic efficiency and the emergence of a wide range of resistant strains, which constitutes a public health risk. This study aimed to evaluate the use of Saccharomyces cerevisiae var. boulardii RC009 as a nutritional feed additive to substitute the prophylactic use of antibiotics and improve the productive performance and health of post-weaning piglets.

Materials and Methods

Four regular nutritional phases were prepared. Post-weaning pigs (21-70 days old) received one of two dietary treatments: T1-basal diet (BD-control group) with in-feed antibiotics as a prophylactic medication (one pulse of Tiamulin in P3 and one pulse of Amoxicillin in P4); and T2-BD without in-feed antibiotics but with Saccharomyces boulardii RC009 (1 × 1012 colony forming unit/T feed). The feed conversion ratio (FCR), total weight gain (TWG-kg), and daily weight gain (DWG-kg) were determined. A post-weaning growth index (GI) was calculated and animals (160 days old) from each treatment were analyzed at the abattoir after sacrifice for carcass weight and respiratory tract lesions.

Results

Pigs consuming probiotics had higher TWG and DWG than the control group. The group of animals with low body weight obtained the same results. Saccharomyces boulardii administration decreased diarrhea, and FCR reduction was related to a GI improvement. A significant increase in carcass weight and muscle thickness reduction was observed in animals received the probiotic post-weaning.

Conclusion

Saccharomyces boulardii RC009, a probiotic additive, was found to improve the production parameters of pigs post-weaning and enhance their health status, indicating that it may be a promising alternative to prophylactic antibiotics.

Antibiotic resistance and associated resistance determinants in different Salmonella enterica serovars isolated from pigs in Argentina

Background and Aim:

Salmonellosis is one of the most common foodborne diseases in the world, and the increasing antibiotic resistance in Salmonella enterica subsp. enterica recovered from food animals constitutes an important risk from a One Health approach. This study aimed to characterize antibiotic resistance and some of its associated resistance determinants in different S. enterica serovars isolated from pigs in Argentina.

Materials and Methods:

A retrospective study was conducted on Salmonella strains isolated between 2011 and 2015 from pigs in the Pampean region of Argentina. The antimicrobial susceptibility patterns to 21 antimicrobials and some antibiotic resistance determinants were characterized in 55 Salmonella isolates, representing 58 farms.

Results:

We identified 56% (n=30) of the strains as multidrug-resistant, where resistance to tetracycline (62%, n=34), ampicillin (53%, n=29), nalidixic acid (53%, n=29), chloramphenicol (33%, n=18), and trimethoprim-sulfamethoxazole (31%, n=17) was most common. The wide range of resistance to ampicillin correlates with the presence of TEM type β-lactamases in the strains. However, high susceptibility was found in the new generation of β-lactams. Fluoroquinolone resistance is a major concern. Most strains with decreased susceptibility to ciprofloxacin showed gyrA mutations and plasmid-mediated quinolone resistance gene qnrB.

Conclusion:

Here, we identified broad resistance to some antibiotics frequently used in human therapeutics and several easily transferable resistance mechanisms that could endanger public health.

Pharmacologycal activity of peperina (Minthostachys verticillata) on gastrointestinal tract

ETHNOPHARMACOLOGICAL RELEVANCE

Minthostachys verticillata (Griseb.) Epling (Lamiaceae), known as Peperina is a medicinal native plant, with a traditional use as a digestive, antispasmodic and antidiarrheic.

AIM OF THE STUDY

Despite its folkloric use, no scientific evaluation of this plant related to the gastrointestinal inflammatory process has been carried out to date. The present study aims to assess the effects of M. verticillata on gastrointestinal system in experimental models.

MATERIALS AND METHODS

M. verticillata (250 and 500 mg/kg) was orally tested in a colitis model induced by acetic acid. Colon weight/length ratio, oxidative stress (oxidized and reduced glutathione), histological changes using Alcian blue and hematoxylin & eosin staining and expression of IL1β, TNFα, iNOS, COX-2 were evaluated. The effect of the extract in three additional in vivo models were studied: intestinal motility and diarrhea induced by ricin oil, and visceral pain induced by intracolonic administration of capsaicin. Finally, the activity on concentration response curves of acetylcholine, calcium chloride, potassium and serotonin were achieved in isolated rat jejunum.

RESULTS

In the colitis model, M. verticillata induced a significant reduction in the colon weight/length ratio, oxidative stress and expression levels of IL-1β, iNOS and COX-2. Also, the extract diminished the severity of microscopic tissue damage and showed protective effect on goblet cells. Intestinal motility, diarrhea, visceral pain-related behaviors and referred hyperalgesia were significantly reduced when the animals were treated with the extract. Furthermore, in isolated jejunum, M. verticillata significantly reduced the contraction induced by serotonin and acetylcholine. Likewise, the extract non-competitively inhibited the response-concentration induced by CaCl2 and inhibited both low and high K+-induced contractions.

CONCLUSIONS

This is the first study to validate traditional use of M. verticillata for digestive disorders and demonstrated that its aqueous extract could represent a promising strategy in targeting the multifactorial pathophysiology of inflammatory bowel disease.

Identification and distribution of Brachyspira species in feces from finishing pigs in Argentina

Background and Aim:

Brachyspira are Gram-negative, aerotolerant spirochetes that colonize the large intestine of various species of domestic animals and humans. The aim of this study was to determine the presence and distribution of different species of Brachyspira presents in feces from finishing pigs in Argentina.

Materials and Methods:

Fecal samples (n=1550) were collected from finishing pigs in 53 farms of the most important swine production areas of Argentina, and Brachyspiras species were identified by bacteriological and molecular methods.

Results:

The regional prevalence of Brachyspira spp. was at the level of 75.5% (confidence interval 95%, 62.9-87.9), and it was lower among those farms with >1001 sows. One hundred and twenty-eight isolates of Brachyspira were properly identified and the species found were: Brachyspira hyodysenteriae, Brachyspira pilosicoli, Brachyspira innocens, and Brachyspira murdochii. B. hyodysenteriae and B. pilosicoli had low prevalence (1.9% and 7.5%, respectively), B. innocens was isolated from 34% of the farms and B. murdochii was found in 39.6%.

Conclusion:

The present study provides epidemiological data about herd prevalence of the different Brachyspira species in Argentina, showing that the prevalence figure seems to be higher than that reported in other countries.

Ureaplasma diversum and Ureaplasma sp. in nasal cavity of pigs: Distribution among herds and individual frequency based on pooled samples

The role of Ureaplasma diversum in the porcine respiratory disease complex (PRDC), its circulation among herds and prevalence in live pigs is unknown; thus, the objectives of this study were: to determine the presence of U. diversum in indoor intensive pig herds and to determine the individual frequency of pigs with U. diversum from pooled samples. A cross sectional study was carried out in 16 indoor intensive herds from Córdoba and La Pampa provinces, collecting eight nasal swabs specimens that were further processed by two pools of four specimens each by a PCR targeting a fragment of 16S ribosomal RNA gene. Four PCR products were sequenced and aligned against data bases. U. diversum - Ureaplasma sp. were detected in 56.3% of the analyzed herds, with 16.5% (95% CI 8.2-30.8) of positive pigs. It was concluded that U. diversum - Ureaplasma sp. are present in the nasal cavity of live pigs, being widely distributed among herds.

Effect of soybean expeller supplementation during the final phase of sow gestation on litter birth weight

Aim

Nutrition plays a key role in the production of pigs, especially in pregnant sows, where modifications in nutritional requirements can affect their productive performance. The aim of this study was to evaluate nutritional supplementation with soybean expeller in sows during the last third of the gestation period and its effect on litter birth weight.

Materials and Methods

A quasi-experimental study was conducted on a farrow-to-finish farm, where 192 sows were equally assigned to treatment and control groups. Several variables were recorded at both the sow and piglet level. The treatment group consisted of piglets from 95 sows supplemented with soybean expeller during the final phase of gestation (20 days), and the comparison group consisted of piglets from 97 sows fed only with a commercial balanced ration (control group).

Results

Soybean expeller supplementation increased individual piglet weight by 190-270 g, and the increased number of live piglets could decrease the weight of each piglet. Moreover, the number of piglets weighing <900 g decreased by 10% as compared to the control group, indicating that supplementation could improve pre-weaning mortality.

Conclusion

Our results suggest that soybean expeller supplementation in sows during the last third of the gestation period could improve production performance, especially on organic farms.

Correction: Porous monoliths synthesized via polymerization of styrene and divinyl benzene in nonaqueous deep-eutectic solvent-based HIPEs

Correction for ‘Porous monoliths synthesized via polymerization of styrene and divinyl benzene in nonaqueous deep-eutectic solvent-based HIPEs’ by M. G. Pérez-García et al., RSC Adv., 2015, 5, 23255–23260.

Microfluidics using a thiol-acrylate resin for fluorescence-based pathogen detection assays

We demonstrate thiol-acrylate microfluidics prepared via soft lithography for single-step protein immobilization and fluorescence-based pathogen detection. Such microfluidics are formed via room temperature curing, and bonded without oxygen plasma. The background fluorescence of the resin was found to be similar to PDMS for several filter sets. We also show that thiol-acrylate devices are able to bond to gold-coated surfaces, which allows for integration with microfabricated sensors.

MLVA typing of Mycoplasma hyopneumoniae bacterins and field strains

Because of the lack of information about both the genetic characteristics of Mycoplasma hyopneumoniae commercial vaccines and their relationship with field strains, the authors attempted to identify genetic subtypes of some M hyopneumoniae bacterins, and to compare them with M. hyopneumoniae field strains. Six commercial M hyopneumoniae bacterins and 28 bronchoalveolar lavages from pigs at slaughter from three herds were analysed by Multiple-Locus Variable number tandem repeat Analysis (MLVA) on p146R1, p146R3, H4, H5 and p95 loci. The results obtained showed the presence of more than one M hyopneumoniae genotype in some pigs and also in one of the bacterins analysed. It is also worth noting that MLVA typing allowed the distinction among circulating field strains and also when comparing them with vaccine strains, which, knowing the relatedness among them, could be useful in the research of the efficacy of the vaccines.

Porous monoliths synthesized via polymerization of styrene and divinyl benzene in nonaqueous deep-eutectic solvent-based HIPEs

Due to their viscosity and polarity, DESs represent a suitable internal phase for HIPEs containing styrenic monomers in addition to acrylates, thus expanding on the range of monomers forming polymerizable DES-based HIPEs.

Processing of lignin in urea–zinc chloride deep-eutectic solvent and its use as a filler in a phenol-formaldehyde resin

The main goal of our research deals with a new greener and more efficient lignin modification method to optimize its structural performance as a phenol-formaldehyde resin filler.

Deep-eutectic solvents as a support in the nonaqueous synthesis of macroporous poly(HIPEs)

Polymerizations of nonaqueous HIPEs with (meth)acrylic monomers as continuous phase and DES as internal phase produce macroporous interconnected polymer monoliths.

Central insulin-angiotensin II interaction in blood pressure regulation in fructose overloaded rats

The aim of the present study was to determine if insulin is able to modulate the pressor response to intracerebroventricularly administered angiotensin II in insulin resistant fructose overloaded rats. Male Sprague-Dawley rats were divided into two groups: 1) Control group (C) with tap water to drink for 6 weeks (n=36); and 2) fructose treated (F), with fructose solution (10% w/v) to drink for 6 weeks (n=36). On the day of the experiment, anesthetized male C and F rats were intracerebroventricularly infused with insulin (12 mU/h, n=15) or Ringer's solution as vehicle (n=15) for 2h. Immediately, changes in mean arterial pressure (MAP) in response to an intracerebroventricular subpressor dose of angiotensin II (5 pmol, n=10) or vehicle (n=5) were measured for 10 min. Then, hypothalami were removed and Akt and ERK1/2 phosphorylation levels were determined. In a subset of C (n=10) and F (n=20) animals, PD98059 (p44/42 MAPK inhibitor) or vehicle was administered intracerebroventricularly at a flow rate of 5 μl/min for 1 min. Ten minutes later, insulin (12 mU/h, n=5 for each group) or vehicle (Ringer's solution, only in the F group, n=5) was perfused for 2h at a flow rate of 4 μl/h, and cardiovascular parameters were measured every 15 min. Immediately, changes in MAP and HR in response to a subpressor dose of Ang II (5 pmol/2 μl) were evaluated for 10 min (n=5 for each group). In other subset of animals (n=6 for each group), AT1 and AT2 hypothalamic receptor levels were measured by Western blotting. Intracerebroventricular insulin pre-treatment increased the pressor response to angiotensin II in C rats. In F rats (with or without insulin pretreatment), the pressor response to angiotensin II was higher than that in vehicle pre-treated C animals, but similar to that observed in C after insulin infusion. In C rats phospho-ERK 1/2 hypothalamic levels significantly increased after angiotensin II injection in insulin pretreated animals compared to vehicle pre-treated rats, suggesting that MAPK activation might be involved in insulin potentiation of blood pressure response to angiotensin II in the brain. Phospho-ERK 1/2 hypothalamic levels were significantly increased in vehicle treated F rats compared to C, suggesting that basal MAPK activation might play a role in the enhanced response to angiotensin II observed in these animals. Finally, in F rats, either after vehicle or insulin infusion, angiotensin II injection was associated with a similar increase in phospho-ERK 1/2 hypothalamic levels, comparable to that observed after angiotensin II injection in insulin pre-treated C animals. ERK 1/2 blockade significantly reduced MAP in F rats compared to C. Moreover, ERK 1/2 inhibition completely abolished the Ang II pressor response in F rats and in insulin pre-treated C animals. All these findings suggest that insulin-angiotensin II interaction at hypothalamic level might be involved in the increase in blood pressure observed in the insulin resistant state.

Metformin reduces vascular production of vasoconstrictor prostanoids in fructose overloaded rats

Metformin is a hypoglycaemic drug currently used to increase insulin sensitivity in the treatment of type 2 diabetes and metabolic syndrome. Its main mechanism of action is through activation of AMP-activated protein kinase, an enzyme that regulates cellular and whole organ metabolism. The fructose-overloaded rat is an experimental model with features that resemble human metabolic syndrome. We have previously reported alterations in vascular prostanoids (PR) in this model. The aim of this study was to analyse the effects of metformin treatment on blood pressure, metabolic parameters and PR production in aorta and mesenteric vascular bed (MVB) from fructose-overloaded animals. Four groups of male Sprague-Dawley rats were used: control, fructose overloaded (10% w/v fructose), metformin treated (50 mg kg(-1) day(-1) ) and fructose-overloaded treated with metformin. Rats with fructose overload had significantly elevated systolic blood pressure, glycaemia, triglyceridaemia, cholesterolaemia and insulinaemia compared with controls. Except for insulinaemia, metformin limited all these increases in fructose-overloaded animals. Fructose overload reduced prostacyclin levels in aorta and MVB, but prostaglandin E(2) levels were only reduced in MVB. Metformin treatment reduced the levels of the vasoconstrictor prostaglandins, PGF(2) α and thromboxane, in both vascular preparations from fructose-overloaded rats. PGF(2) α levels were significantly reduced by metformin in controls. In conclusion, one of the mechanisms by which metformin reduced blood pressure in this model is by decreasing vasoconstrictor prostaglandin production.

Domestic queens under natural temperate photoperiod do not manifest seasonal anestrus

Domestic cat seasonality between the tropics and the arctic zones is scarcely described and results are inconsistent. The aim of this study was to describe domestic feline seasonal patterns under a natural temperate photoperiod. A total of 372 estrous cycles were studied in 34 post pubertal cats during 900 days. The queens were housed in a cat colony (31°25' South Latitude, 64°11' West Longitude), acclimated under natural photoperiod and daily observed for reproductive behavior. Vaginal cytology was conducted three times a week. For each cat the number of estrous cycles and days in estrus per month for each year were recorded. The months of the year were grouped in four periods of 3 months each according to day length and photoperiod. Comparisons of estrous days among periods were performed by ANOVA for repeated measures. All the cats had estrous cycles throughout the year without intervals of anestrus. Mean number of estrous days differed among the periods (P<0.01), those of long day length and ascending photoperiod being greater (12.5±0.6) to those of descending photoperiod either with long (8.9±0.7) or short (9.3±0.7) days. When the two periods with ascending day lengths were merged and compared to the two periods with descending day lengths merged, the number of estrous days were greater when day length ascended (P<0.01). Nearly 60% of the estrous cycles occurred during the periods of ascending day length. It is concluded, that domestic cats under natural temperate photoperiod have estrous cycles throughout the year showing peak activity the months with increasing photoperiod.

Lipopolysaccharide (LPS) induction of nitric oxide synthase-2 and cyclooxygenase-2 is impaired in fructose overloaded rats

AIMS

Fructose (F) overload in rats induces metabolic dysfunctions that resemble the human metabolic syndrome. In this paper, we aimed to investigate the response of F overload rats to lipopolysaccharide (LPS) challenge in terms of nitric oxide (NO) production and prostanoids (PR) release.

MAIN METHODS

NO blood steady-state concentration was monitored through the detection of nitrosyl-hemoglobin complexes (NO-Hb) by electronic spin resonance. Production of 6-keto PGF(1)α, PGE(2), PGF(2)α and TXB(2) was measured in aorta and mesenteric beds by HPLC. Western blot analysis was used to examine the changes in the expression levels of NOS-2 and COX-2 in aorta.

KEY FINDINGS

Our results showed that increases in NO circulating steady-state concentration and PR production by aorta and mesenteric beds 6h after LPS administration were significantly attenuated in F overload rats with respect to control animals. Oxidative stress parameters were equally affected in the presence or absence of the F treatment. Aorta protein levels of NOS-2 and COX-2, two enzymes inducible by LPS, were significantly lower in F overload rats with respect to control rats at the end of the treatment (-39% and -61% for NOS-2 and COX-2 respectively).

SIGNIFICANCE

These results suggest that the metabolic alterations established by 15 weeks of F overload should affect the response to LPS challenge due to an attenuation in the induction of NOS-2 and COX-2. This effect would be one of the components contributing to abnormalities in the course of the inflammatory response in other conditions associated to insulin resistance, such as diabetes.

East pacific rise: hot springs and geophysical experiments

Hydrothermal vents jetting out water at 380 degrees +/- 30 degrees C have been discovered on the axis of the East Pacific Rise. The hottest waters issue from mineralized chimneys and are blackened by sulfide precipitates. These hydrothermal springs are the sites of actively forming massive sulfide mineral deposits. Cooler springs are clear to milky and support exotic benthic communities of giant tube worms, clams, and crabs similar to those found at the Galápagos spreading center. Four prototype geophysical experiments were successfully conducted in and near the vent area: seismic refraction measurements with both source (thumper) and receivers on the sea floor, on-bottom gravity measurements, in situ magnetic gradiometer measurements from the submersible Alvin over a sea-floor magnetic reversal boundary, and an active electrical sounding experiment. These high-resolution determinations of crustal properties along the spreading center were made to gain knowledge of the source of new oceanic crust and marine magnetic anomalies, the nature of the axial magma chamber, and the depth of hydrothermal circulation.

Immunolocalization of NK-1 receptor and Substance P in human normal placenta

A role for Substance P (SP) in human placenta is not known, although is possible that regulates placental physiology through the Neurokinin (NK)-1 receptor. Ten human normal placenta tissues were studied by immunohistochemistry to demonstrate the localization of NK-1 receptor and SP. An immunostaining pattern for NK-1 receptor and SP was observed in the endothelium and myocytes of fetal blood vessels, decidua and trophoblast. The SP is located in both the cytoplasm and the nucleus whereas NK-1 receptor in cytoplasmic. These findings reported here for the fist time, suggest a role for the SP and NK-1 receptor in the placental physiology.

On the benthic molluscs of Banco Inglés (Río de la Plata, Uruguay)

We describe the specific richness and community structure of benthic molluscs on a shallow-water sandy bank (Banco Inglés) in the Río de la Plata estuary. From a total of 25 macroinvertebrate taxa collected, that included one ophiuroid, one bryozoan, fourcrustaceans and four polychaete species, molluscs were the dominant taxon, with 15 species recorded. These were one species of Polyplacophora, eight Bivalvia and six Gastropoda (one exotic), representing 11families and 11 genera. In terms of mean relative abundance, the molluscan assemblage was dominated by the deposit-feeder bivalve Corbula caribaea, averaging ca. 30% of the individuals of the macroinfauna. The alien species Rapana venosa was noted in two stations, represented by one and four specimens. We used null model analysis to test for nonrandomness in the structure of the molluscan communities of the area. The analysis supported the null hypothesis that co-occurrence patterns could not be distinguished from those that might arise by random processes.

Pre-ischemic exercise reduces matrix metalloproteinase-9 expression and ameliorates blood-brain barrier dysfunction in stroke

Exercise reduces ischemia and reperfusion (I/R) injury in the rat stroke model. We investigated whether pre-ischemic exercise ameliorates blood-brain barrier (BBB) dysfunction in stroke by reducing matrix metalloproteinase (MMP)-9 expression and strengthening basal lamina. Adult male Sprague-Dawley rats were subjected to a 30 min exercise program on a treadmill 5 days a week for 3 weeks. Stroke was induced by a 2-h middle cerebral artery (MCA) occlusion using an intraluminal filament in the exercised and non-exercised groups. Brain infarction was measured and neurological deficits were scored. BBB dysfunction was determined by examining brain edema and Evans Blue extravasation. Expression of collagen IV, the major component of basal lamina essential for maintenance of the endothelial permeability barrier, was quantitatively detected by Western blot and immunocytochemistry. Ex vivo techniques were used to compare collagen IV-labeled vessels in response to ischemic insult. Temporal relationship of expression of MMP-9 and its endogenous inhibitor, the tissue inhibitors of metalloproteinase-1 (TIMP-1), was determined by real-time PCR for mRNA and Western blot for protein during reperfusion. Brain edema and Evans Blue leakage were both significantly (P<0.01) reduced after stroke in the exercised group, in association with reduced brain infarct volume and neurological deficits. Western blot analysis indicated that exercise enhanced collagen IV expression and reduced the collagen loss after stroke. Immunocytochemistry demonstrated that collagen IV-labeled vessels were significantly (P<0.01) increased in exercised rats. In the ex vivo study, after exercised brains were incubated with ischemic brain tissue, a significantly (P<0.01) higher level of collagen IV-labeled vessels was observed as compared with non-exercised brains following the same treatment. The ex vivo study also revealed a key role of MMP-9 in exercise-strengthened collagen IV expression against I/R injury. TIMP-1 protein levels were significantly (P<0.01) increased by exercise. Our results indicate that pre-ischemic exercise reduces brain injury by improving BBB function and enhancing basal lamina integrity in stroke. This study suggests that the neuroprotective effect of physical exercise is associated with an imbalance of MMP-9 and TIMP-1 expression.

Two new records of Pycnogonids on the Uruguayan coast

The Pycnogonida from Uruguayan waters are scarcely known, and their reports are markedly discontinuous. In this paper, several individuals of two previously unrecorded Pycnogonids at the shallow rocky subtidal and lower intertidal fringes of Cerro Verde (Rocha, Uruguay) are reported. The specimens were assigned to Pycnogonum pamphorum Marcus, 1940 and Anoplodactylus petiolatus (Kroyer, 1844). This is the first record of these species on the Uruguayan coast and the southernmost record of P. pamphorum, previously recorded only in Santos, Brazil (type locality).

Low sodium intake induces an increase in renal monoamine oxidase activity in the rat. Involvement of an angiotensin II dependent mechanism

AIMS

The interplay between natriuretic dopamine and antinatriuretic angiotensin II represents an important mechanism for the regulation of renal sodium and water excretion. Monoamine oxidase is the main metabolizing pathway for dopamine in the renal cortex. In this study, we have analysed the effect of low sodium feeding and AT1 receptor blockade on renal dopamine metabolism by monoamine oxidase.

METHODS

Four groups of rats were studied: 1, normal salt diet (NS); 2, low salt diet (LS); 3, NS receiving Losartan (Los, specific AT1 receptor antagonist, 20 mg kg(-1) bwt day(-1), NS + Los); 4, LS receiving Los (LS + Los).

RESULTS

Urinary dopamine excretion was lower in LS than in NS rats (543 +/- 32 vs. 680 +/- 34 ng day(-1) 100 g(-1) bwt, P < 0.05). When treated with Los, DOPAC excretion and urinary DOPAC/dopamine ratio fell significantly in the LS + Los group as compared with the LS group (1199 +/- 328 vs. 3081 +/- 681 ng day(-1) 100 g(-1) bwt and 1.90 +/- 0.5 vs. 5.7 +/- 1.2, respectively, both P < 0.02). Losartan increased hydroelectrolyte excretion in the LS group. No changes were found in the NS + Los group. Aromatic L-amino acid decarboxylase activity in cortex was similar in NS and LS rats. Instead, monoamine oxidase activity was higher in cortical homogenates from LS rats (in nmol mg tissue(-1) h(-1): NS 7.66 +/- 0.52; LS 9.82 +/- 0.59, P < 0.05) and this difference was abolished in LS + Los rats (7.34 +/- 0.49 nmol mg tissue(-1) h(-1), P < 0.01, vs. LS).

CONCLUSIONS

We have concluded that low levels of dopamine in the urine of LS rats are because of an increase in the activity of renal monoamine oxidase and that angiotensin II mediates this increase through stimulation of AT1 receptors.

[Helicobacter pylori in children in Hospital Nacional de Niños, San José de Costa Rica]

Infection with Helicobacter pylori is more prevalent in developing than in developed countries. Several publications from Costa Rica associate this agent with almost 70% of the adults suffering gastritis; however, there are not data about its prevalence in children. In order to address that gap in the epidemiology of Helicobacter pylori in Costa Rica, we study 264 children (3 months to 17 years old) remitted to upper endoscopy due to dyspeptic disorders. From each case at least two biopsies were taken; one for Helicobacter isolation and the others for histopathological study. 96 of the children showed any grade of gastritis and in 73 of them was identified H. pylori; also, this agent was associated with 11 of the children without alteration in their gastric mucosa. In total, H. pylori was identified in the 31.8% of the studied cases. The two younger patients infected were a 1 and 2 years-old boys; the former had normal mucosa and the other had gastritis. These data confirm the importance of investigate Helicobacter in young children with gastric discomfort, mainly in developing countries.

Decreased tubular uptake of L-3,4-dihydroxyphenylalanine in streptozotocin-induced diabetic rats

BACKGROUND/AIMS

This study determined alterations in renal dopamine production in streptozotocin-treated rats and explored the mechanisms underlying this alteration.

METHODS

Streptozotocin (65 mg/kg) or vehicle was administered to 3-month-old male Wistar rats. Treated animals had hyperglycemia, glycosuria and increased diuresis, natriuresis and excretion of L-dopa. Urinary dopamine and dihydroxyphenylacetic acid were similar to those in control animals. The production of dopamine by renal cortex slices from treated rats was significantly less than that from control animals. The addition of glucose (8.4-18.4 mM) to the incubation medium decreased about 40% the uptake of L-dopa by isolated proximal tubular cells. Scatchard analysis of the saturation curves obtained in this condition showed a decrease in the V(max) without changes in the K(m).

RESULTS

Our results confirm previous studies suggesting a renal dopaminergic deficiency in insulin-dependent diabetes and provide evidence strongly suggesting that a decrease in the number of tubular L-dopa transport sites is the underlying defect of this deficiency.

CONCLUSION

These results highlight the role of the uptake of dopa as an important modulator of renal dopamine synthesis.

Peripheral administration of an angiotensin II AT(1) receptor antagonist decreases the hypothalamic-pituitary-adrenal response to isolation Stress

Angiotensin II, which stimulates AT(1) receptors, is a brain and peripheral stress hormone. We pretreated rats with the AT(1) receptor antagonist candesartan for 13 d via sc-implanted osmotic minipumps, followed by 24-h isolation in individual metabolic cages. We measured angiotensin II receptor-type binding and mRNAs and tyrosine hydroxylase mRNA by quantitative autoradiography and in situ hybridization, catecholamines by HPLC, and hormones by RIA. Isolation increased AT(1) receptor binding in hypothalamic paraventricular nucleus as well as anterior pituitary ACTH, and decreased posterior pituitary AVP. Isolation stress also increased AT(1) receptor binding and AT(1B) mRNA in zona glomerulosa and AT(2) binding in adrenal medulla, adrenal catecholamines, tyrosine hydroxylase mRNA, aldosterone, and corticosterone. Candesartan blocked AT(1) binding in paraventricular nucleus and adrenal gland; prevented the isolation-induced alterations in pituitary ACTH and AVP and in adrenal corticosterone, aldosterone, and catecholamines; abolished the increase in AT(2) binding in adrenal medulla; and substantially decreased urinary AVP, corticosterone, aldosterone, and catecholamines during isolation. Peripheral pretreatment with an AT(1) receptor antagonist blocks brain and peripheral AT(1) receptors and inhibits the hypothalamic-pituitary-adrenal response to stress, suggesting a physiological role for peripheral and brain AT(1) receptors during stress and a possible beneficial effect of AT(1) antagonism in stress-related disorders.

In vitro interaction of bacteria with polypropylene/ePTFE prostheses

The infection of an implanted prosthetic material can have serious consequences on the tissue integration of the implant and the scarring process in the host, and may even necessitate replacement of the prosthesis. This study was designed to explore the in vitro effects of Staphylococcus aureus (Sa) and Staphylococcus epidermidis (Se) on polypropylene (PL) and expanded polytetrafluoroethylene (ePTFE) prostheses. Fragments of PL and ePTFE were placed in a medium previously inoculated with Sa, Se or Sa + Se (1 x 10(8) cfu Sa or/and Se). Bacterial effects on the biomaterials were evaluated for 30 days through scanning electron microscopy (SEM). In order to confirm the presence of bacteria on the prostheses, specimens were Gram stained and challenged with an antibody against protein-A (a specific Sa bacterial wall component). In both methods, specimens were examined by light microscopy. The presence of bacteria as microcolonies or biofilms was detected at PL filament cross-over regions after 30 days. Bacterial colonization of the ePTFE fragments was observed in internodal areas, which led to the deformation of prosthetic filaments. The present findings indicate that Sa and Se colonize the cross-over regions of the PL filaments, whereas in ePTFE prostheses, it is the internodal areas which are mostly affected. The latter areas are of difficult access to defence agents.

Selective inner hair cell loss in premature infants and cochlea pathological patterns from neonatal intensive care unit autopsies

BACKGROUND

Deafness and handicapping sensorineural hearing impairment occur frequently in neonatal intensive care unit survivors for unknown reasons.

PATIENTS AND METHODS

Hearing was tested early and repeatedly in neonatal intensive care unit patients with an auditory brainstem response (ABR) screener. The temporal bones of 15 nonsurvivors (30 ears) were fixed promptly (average, 5 hours) after death for histological evaluation.

RESULTS

Among these patients, 12 failed the ABR screen bilaterally, 1 passed unilaterally, and 2 passed bilaterally. Cochlear histopathologic conditions that could contribute to hearing loss included bilateral selective outer hair cell loss in 2 patients, bilateral selective inner hair cell loss in 3 (all premature), and a combination of both outer and inner hair cell loss in 2. Other hair cell abnormalities were noted; the 2 infants who had passed the ABR screen demonstrated normal histological features. Neuronal counts were normal.

CONCLUSIONS

Auditory brainstem response failure among these neonatal intensive care unit infants who died was extremely common in part owing to an unexpected histological alteration, selective inner hair cell loss among premature newborns, that should be detectable uniquely by the ABR testing method. Additional histological patterns suggest more than one cause for neonatal intensive care unit hearing loss. Hair cell loss patterns seem frequently compatible with in utero damage.

L-Dopa uptake and dopamine production in proximal tubular cells are regulated by beta(2)-adrenergic receptors

This study assessed the role of adrenergic receptors on the regulation of the uptake of L-dopa and the production of dopamine by renal tubular cells. Scatchard analysis showed two L-dopa uptake sites with different affinities (K(m) 0.316 vs 1.53 microM). L-Dopa uptake was decreased by the nonselective adrenergic agonists epinephrine or norepinephrine (40%), by the beta-selective agonist isoproterenol or the beta(2)-selective agonist terbutaline (60%), but not by alpha-selective agonists (all 1 microM). The effect of norepinephrine, isoproterenol, or terbutaline was unaffected by addition of the beta(1)-antagonist atenolol, abolished by ICI-118, 551, a beta(2)-antagonist (both 0.1 microM), and mimicked by the addition of dibutyryl-cAMP (1 microM). Preincubation with terbutaline decreased the number of high-affinity uptake sites (V(max) = 1.10 +/- 0.3 vs. 0.5 +/- 0.1 pmol. mg protein(-1). min(-1)) without changing their affinity. Norepinephrine or terbutaline decreased dopamine production by isolated cells, and this effect was abolished by ICI-118,551 (0.1 microM). In vivo administration of ICI-118,551 reduced the urinary excretion of L-dopa and increased the excretion of 3,4-dihydroxyphenylacetic acid without significant changes in plasma L-dopa concentrations. These results demonstrate that stimulation of beta(2)-adrenergic receptors decreases the number of high-affinity L-dopa uptake sites in isolated tubular cells resulting in a reduction of the uptake of L-dopa and the production of dopamine and provide evidence for the presence of this mechanism in the intact animal.

Disseminated histoplasmosis in infants

BACKGROUND

Disseminated histoplasmosis usually occurs in immunocompromised patients who reside in Histoplasma capsulatum-endemic regions. It has also been described in immunocompetent infants after exposure to a large inoculum of the pathogen resulting in case fatality rates of 40 to 50%.

METHODS

From 1983 through 1996 all infants with documented disseminated histoplasmosis were treated with amphotericin B followed by daily ketoconazole for 3 months. Immunologic workups were performed at the time of diagnosis and at 4 to 6 weeks of therapy. Surviving patients were followed for at least 1 year. Time to resolution of signs and symptoms was recorded, as were complications.

RESULTS

We managed 40 patients with disseminated histoplasmosis. The age in months at diagnosis was 15.3+/-10.2 (mean +/- SD), and 24 were male. All patients were from endemic regions and they presented with fever, spleen and/or liver enlargement and hematologic abnormalities. Diagnosis was made by histology and culture of bone marrow, spleen, lymph node, bronchoalveolar or liver samples. Twenty patients presented with T cell deficiency that resolved at 4 to 6 weeks of therapy in all of the retested patients, and 10 of 12 tested patients had hyperglobulinemia that resolved. Thirty-five (88%) patients were cured by treatment; 4 died and 1 relapsed.

CONCLUSIONS

Disseminated histoplasmosis should be considered in infants from endemic areas who present with fever, hepatosplenomegaly and hematologic abnormalities. These patients develop transient hyperglobulinemia and T cell deficiency that resolve with treatment. Treatment with amphotericin B followed by an oral azole for 3 months is effective in most patients.

Complete absence or deficiency of one half of the body

Here we report on an apparently unprecedented case of virtually complete absence of the left half of the body, with resulting severe deformity of the right half. The fetus was stillborn with polyhydramnios at 31 1/2 weeks of gestational age. A second patient may be a mild example of this extraordinary phenomenon with deficiency of organs, predominantly on the left side. The nosology and developmental implications are discussed briefly.

Intraotic administration of gentamicin: a new method to study ototoxicity in the crista ampullaris of the bullfrog

A new method of local gentamicin administration was tested in the bullfrog inner ear to achieve ototoxic-induced hair cell destruction. Gelfoam pledgets soaked with known amounts of gentamicin were inserted into the perilymphatic cisterna of the bullfrog through a ventral surgical approach. A dose of 1.20 mg gentamicin, consistent with a perilymphatic concentration of 65 microg/ml, resulted in the desired ototoxic-induced hair cell damage, that is, complete hair cell destruction with minimal disruption of other components of the sensory epithelium. This study demonstrates that this is a useful and simple method to investigate the process of vestibular ototoxicity and hair cell regeneration, including aspects of hair cell destruction and repair.

Suppression of the reactive hyperemic response in the forearm due to local hand cooling

METHODS

Forearm blood flow (FBF) was measured by electrical impedance plethysmography in order to identify the influence of local cooling of the contralateral hand after 3 min of arterial occlusion. Ten volunteers (six females, four males) were randomly assigned to the following three experimental conditions on separate days: a) 6 min of local hand cooling (5-7 degrees C); b) 3 min of arterial occlusion of the forearm; and c) combined arterial occlusion and local cooling.

RESULTS

All subjects experienced the typical pressor response during 6 min of hand cooling as evidenced by the significant increase (p < and = 0.05) in heart rate (HR), systolic blood pressure (SBP), and diastolic blood pressure (DBP). The FBF responses demonstrated an immediate increase (p < and = 0.05) within the first 30 s of hand submersion and then progressively declined over the next 5 min. The forearm vascular resistance (FVR = MAP/FBF) made an initial drop during the first 30 s of cooling and then gradually rose to reach peak levels between 5-6 min of cooling. With respect to the hyperemic response, FBF significantly increased (p < and = 0.05) from baseline (mean +/- SEM; 1.09 +/- 0.18 ml x 100 ml-1.min-1) and achieved peak levels (6.75 +/- 0.64 ml x 100 ml-1.min-1) within the initial 30 s of the post-occlusion period. Thereafter, FBF declined rapidly by 30-60 s (1.67 +/- 0.29 ml x 100 ml-1.min-1) and 60-90 s (1.26 +/- 0.33 ml x 100 ml-1.min-1) of the post-occlusion period.

CONCLUSION

When the reactive hyperemic response was coupled with hand cooling, FBF increased above baseline values and reached peak levels during the initial 30 s of the post-occlusion period. However, the magnitude of the hyperemic response was significantly lower in the cold condition compared to the hyperemia alone (3.20 +/- 0.42 vs 6.75 +/- 0.64 ml x 100 ml-1.min-1; p < and = 0.05). Clearly, the overall sympathetic response to local cooling had an overriding effect on the factors that promote peripheral vasodilation following brief periods (3 min) of arterial occlusion.

[Neuroblastoma in Costa Rica: the experience with 76 cases treated at the Hospital Nacional de Niños]

Between 1970 an 1988, 76 patients with neuroblastoma (39 males and 37 females) were treated at the National Children's Hospital. The children's ages ranged from 1 month to 10 years. The location of the neuroblastoma was retroperitoneal in 71% of the cases, mediastinal in 20%, in either the head or neck 4% and unknown in 5%. Twelve percent were classified as E I-II, 35% in E III, 50% in E IV and 3% in E IVS. Seventy-seven percent of the cases died and the remaining 33% are in remission, with a follow-up of 12 to 220 months. Fifty of the cases were histologically reclassified according to Shimada. Survival rates were correlated with age, histology, E classification and treatment, in order to establish prognostic factors in relation to the disease: children under 24 months have a survival rate of 43%, statistically greater than in those children older who have an 8% survival rate. Shimada's classification is useful in predicting the child's survival when under 18 months of age and with tumors with a low ICM (81% survival) and a high ICM (6%). Patients classified as E I-II have a survival rate of 74%, those in E III-38% and in E IV-4%. In relation to the chemotherapy, a ten year survival is thought to be 14% for the 22 cases in E III and IV who were given medication and 21% for the other 36 who were given three drugs.(ABSTRACT TRUNCATED AT 250 WORDS)

[Thyroid nodules in children. Experience at the National Children Hospital of Costa Rica]

Clinical charts and biopsies of 32 children with thyroid nodules were reviewed at the National Children's Hospital from 1970 to 1988. The classification between benign and malignant types was only possible by surgery and biopsy. Twenty three (72%) were found to be benign forms and nine (28%) were carcinomas (8 papillary and one follicular). Two of the carcinomas had been irradiated previously because of neuroblastoma, as well as one of the benign type who received radiation to the neck and mediastinum because of a Hodgkin's disease. No patients showed alteration in thyroid functional test (T4 and TSH). Twenty two per cent of the carcinomas and 16% of the benign forms presented higher retention in the gammagram test. Seventy eight per cent of the carcinomas and 70% of the benign types showed a normal gammagram test. Surgery in the benign cases included 10 hemithyroidectomy, 7 sub-total thyroidectomy, 3 total thyroidectomy and 3 node resection. Carcinoma cases included 6 patients with total thyroidectomy with ganglionar modified dissection in three patients; 2 hemithyroidectomy and one with sub-total thyroidectomy. Complications included 3 hypoparathyroidisms, one of them permanent, 3 transitory recurrent paresis and only one child died because of pulmonary metastasis. All carcinoma patients were treated with levothyroxine and three of them also received 1131 in order to control ganglionar metastasis. Total survival rate for carcinoma patients was 83% at 90 months. It is concluded that only with surgery it is possible to classify correctly the histological type of children with thyroid nodes. Clinical evaluation and laboratory tests are useless. However, it has not been defined how big the surgery must be.(ABSTRACT TRUNCATED AT 250 WORDS)

Treatment and outcome of undifferentiated carcinoma of the nasopharynx in childhood: a 13-year experience

Between 1970 and 1983, 22 pediatric patients diagnosed as having undifferentiated nasopharyngeal carcinoma (UNC) were treated at the National Children's Hospital of Costa Rica; primary tumor with local extension (T3-T4) was present in 45% of the patients, and metastasis of the cervical nodes (N1-N3) in 82%. Patients were divided into groups A and B according to the type of treatment received. A description of both groups is as follows. Ten patients were treated with 5,000 to 6,000 rads tumor dose to the primary and a 5,125-rad dose was administered to the lower neck between 1970 and 1977 (group A). Six patients received postradiation therapy with cyclophosphamide and vincristine and two patients also received 5-fluorouracil. The outcome in group A was as follows: four (40%) failed to respond, six (60%) achieved full remission initially with two subsequent relapses, and the remaining four are still alive and free of relapse after 90 to 160 months (average 130) (two were treated with Co60 alone and two with chemotherapy. Twelve patients were treated with chemotherapy pre- and postradiation with CPM and adriamycin for a total of 12 months (group B) between 1978 and 1984. All (100%) achieved complete initial remission; two patients relapsed and died. Ten patients have remained in relapse-free survival for 18-67 months (median 32). Though this is not a controlled study, our experience indicates that pre- and postradiation chemotherapy is effective in prolonging the disease-free survival in UNC and may allow a decrease of the radiation tumor dose.