Hypoxic glioblastoma-cell-derived extracellular vesicles impair cGAS-STING activity in macrophages

BACKGROUND

Solid tumors such as glioblastoma (GBM) exhibit hypoxic zones that are associated with poor prognosis and immunosuppression through multiple cell intrinsic mechanisms. However, release of extracellular vesicles (EVs) has the potential to transmit molecular cargos between cells. If hypoxic cancer cells use EVs to suppress functions of macrophages under adequate oxygenation, this could be an important underlying mechanism contributing to the immunosuppressive and immunologically cold tumor microenvironment of tumors such as GBM.

METHODS

EVs were isolated by differential ultracentrifugation from GBM cell culture supernatant. EVs were thoroughly characterized by transmission and cryo-electron microscopy, nanoparticle tracking analysis (NTA), and EV marker expression by Western blot and fluorescent NTA. EV uptake by macrophage cells was observed using confocal microscopy. The transfer of miR-25/93 as an EV cargo to macrophages was confirmed by miRNA real-time qPCR. The impact of miR-25/93 on the polarization of recipient macrophages was shown by transcriptional analysis, cytokine secretion and functional assays using co-cultured T cells.

RESULTS

We show that indirect effects of hypoxia can have immunosuppressive consequences through an EV and microRNA dependent mechanism active in both murine and human tumor and immune cells. Hypoxia enhanced EV release from GBM cells and upregulated expression of miR-25/93 both in cells and in EV cargos. Hypoxic GBM-derived EVs were taken up by macrophages and the miR-25/93 cargo was transferred, leading to impaired cGAS-STING pathway activation revealed by reduced type I IFN expression and secretion by macrophages. The EV-treated macrophages downregulated expression of M1 polarization-associated genes Cxcl9, Cxcl10 and Il12b, and had reduced capacity to attract activated T cells and to reactivate them to release IFN-γ, key components of an efficacious anti-tumor immune response.

CONCLUSIONS

Our findings suggest a mechanism by which immunosuppressive consequences of hypoxia mediated via miRNA-25/93 can be exported from hypoxic GBM cells to normoxic macrophages via EVs, thereby contributing to more widespread T-cell mediated immunosuppression in the tumor microenvironment.

Co-Formulation of Recombinant Porcine IL-18 Enhances the Onset of Immune Response in a New Lawsonia intracellularis Vaccine

Pig is one of the most consumed meats worldwide. One of the main conditions for pig production is Porcine Enteropathy caused by Lawsonia intracellularis. Among the effects of this disease is chronic mild diarrhea, which affects the weight gain of pigs, generating economic losses. Vaccines available to prevent this condition do not have the desired effect, but this limitation can be overcome using adjuvants. Pro-inflammatory cytokines, such as interleukin 18 (IL-18), can improve an immune response, reducing the immune window of protection. In this study, recombinant porcine IL-18 was produced and expressed in Escherichia coli and Pichia pastoris. The protein's biological activity was assessed in vitro and in vivo, and we determined that the P. pastoris protein had better immunostimulatory activity. A vaccine candidate against L. intracellularis, formulated with and without IL-18, was used to determine the pigs' cellular and humoral immune responses. Animals injected with the candidate vaccine co-formulated with IL-18 showed a significant increase of Th1 immune response markers and an earlier increase of antibodies than those vaccinated without the cytokine. This suggests that IL-18 acts as an immunostimulant and vaccine adjuvant to boost the immune response against the antigens, reducing the therapeutic window of recombinant protein-based vaccines.

Evaluation of the Pediatric Neuro-Oncology Resources Available in Chile

PURPOSE

Pediatric neuro-oncology resources are mostly unknown in Chile. We report the human and material resources available in Chilean hospitals providing pediatric neuro-oncology services.

METHODS

A cross-sectional survey was distributed to 17 hospitals providing pediatric neuro-oncology services (Programa Infantil Nacional de Drogas Antineoplásicas [PINDA] hospitals, 11; private, 6).

RESULTS

Response rate was 71% (PINDA, 8; private, 4). Pediatric neuro-oncology services were mainly provided within general hospitals (67%). Registries for pediatric CNS tumors and chemotherapy-related toxicities were available in 100% and 67% of hospitals, respectively. CNS tumors were treated by pediatric oncologists in 92% of hospitals; none were formally trained in neuro-oncology. The most used treatment protocols were the national PINDA protocols. All WHO essential medicines for childhood cancer were available in more than 80% of the hospitals except for gemcitabine, oxaliplatin, paclitaxel, and procarbazine. The median number of pediatric neurosurgeons per hospital was two (range, 2-6). General neuroradiologists were available in 83% of the centers. Pathology specimens were sent to neuropathologists (58%), adult pathologists (25%), and pediatric pathologists (17%). Intensity-modulated radiotherapy, conformal radiotherapy, and cobalt radiotherapy were used by 67%, 58%, and 42% of hospitals, respectively. Only one private hospital performed autologous hematopoietic cell transplant for children with CNS tumors.

CONCLUSION

A wide range of up-to-date treatment modalities are available for children with CNS tumors. Our survey highlights future directions to improve the pediatric neuro-oncology services available in Chile such as the expansion of multidisciplinary clinics, palliative care services, long-term cancer survivorship programs, dedicated clinical research support teams, establishing standardized mechanism for sending pathologic specimen for second opinion to international specialized centers, and establishing specialized neuro-oncology training program.

LINC-21. SURVEY ON THE RESOURCES AVAILABLE FOR PEDIATRIC NEURO-ONCOLOGY IN CHILE, SOUTH AMERICA

BACKGROUND

We report the human and material resources available in Chilean institutions providing pediatric neuro-oncology services.

METHODS

A cross-sectional survey was distributed to 17 hospitals providing pediatric neuro-oncology services (Programa Infantil Nacional de Drogas Antineoplásicas (PINDA) centers=11, Private=6).

RESULTS

Response rate was 71% (PINDA=8; Private=4). Pediatric neuro-oncology services were mainly provided within general hospitals (67%). Registries for pediatric central nervous system (CNS) tumors and chemotherapy-related toxicities were available in 100% and 67% of centers, respectively. Children with CNS tumors were treated by pediatric oncologists in 92% of institutions; none were formally trained in neuro-oncology. The most utilized treatment protocols were the national PINDA protocols followed by the Children’s Oncology Group protocols. All World Health Organization essential medicines for childhood cancer were available in more than 80% of participating institutions except for gemcitabine, oxaliplatin, paclitaxel, and procarbazine. The median number of pediatric neurosurgeons per institution was two (range,0–8). General neuro-radiologists were available in 83% of institutions. Pathology specimens were sent to pediatric neuropathologists (33%), neuropathologists (25%), adult pathologists (25%), and pediatric pathologists (16.7%). In-house pediatric radiation oncologists were available in 25% of centers. Intensity-modulated radiotherapy, conformal radiotherapy and cobalt radiotherapy were utilized by 67%, 58% and 42% of hospitals, respectively. Only one center performed autologous hematopoietic cell transplant for pediatric CNS tumors.

CONCLUSIONS

These results provide a glimpse into the pediatric neuro-oncology services available in Chile. A wide range of up-to-date treatment modalities is available for children with CNS tumors in Chile. Establishing formal pediatric neuro-oncology training may be beneficial.

Cytogenetic relationships, polyploid origin and taxonomic issues in Paspalum species: inter- and intraspecific hybrids between a sexual synthetic autotetraploid and five wild apomictic tetraploid species

Paspalum is a noteworthy grass genus due to the forage quality of most species, with approximately 330 species, and the high proportion of those that reproduce via apomixis. Harnessing apomictic reproduction and widening knowledge about the cytogenetic relationships among species are essential tools for plant breeding. We conducted cytogenetic analyses of inter- and intraspecific hybridisations involving a sexual, colchicine-induced autotetraploid plant of P. plicatulum Michx. and five indigenous apomictic tetraploid (2n = 40) species: P. compressifolium Swallen, P. lenticulare Kunth, two accessions of P. nicorae Parodi, P. rojasii Hack. and two accessions of P. plicatulum. Fertility of the hybrids was investigated and their reproductive system was analysed considering the relative embryo:endosperm DNA content from flow cytometry. Morphological, nomenclatural and taxonomic issues were also analysed. Cytogenetic analysis suggested that all indigenous tetraploid accessions of five apomictic species are autotetraploid or segmental allotetraploid. If segmental allotetraploids, they probably originated through autoploidy followed by diploidisation processes. Autosyndetic male chromosome pairing observed in all hybrid families supported this assertion. Allosyndetic chromosome associations were also observed in all hybrid families. In the hybrids, the proportion of male parent chromosomes involved in allosyndesis per pollen mother cell varied from 5.5% to 35.0% and the maximum was between 25% and 60%. The apomictic condition of the indigenous male parents segregated in the hybrids. These results confirm a strong association between autoploidy and apomixis in Paspalum, and the existence of cytogenetic relationships between different species of the Plicatula group. Allosyndetic chromosome pairing and seed fertility of the hybrids suggest the feasibility of gene transfer among species.

Relative DNA content in diploid, polyploid, and multiploid species of Paspalum (Poaceae) with relation to reproductive mode and taxonomy

It is generally accepted that polyploids have downsized basic genomes rather than additive values with respect to their related diploids. Changes in genome size have been reported in correlation with several biological characteristics. About 75 % of around 350 species recognized for Paspalum (Poaceae) are polyploid and most polyploids are apomictic. Multiploid species are common with most of them bearing sexual diploid and apomictic tetraploid or other ploidy levels. DNA content in the embryo and the endosperm was measured by flow cytometry in a seed-by-seed analysis of 47 species including 77 different entities. The relative DNA content of the embryo informed the genome size of the accession while the embryo:endosperm ratio of DNA content revealed its reproductive mode. The genome sizes (2C-value) varied from 0.5 to 6.5 pg and for 29 species were measured for the first time. Flow cytometry provided new information on the reproductive mode for 12 species and one botanical variety and supplied new data for 10 species concerning cytotypes reported for the first time. There was no significant difference between the mean basic genome sizes (1Cx-values) of 32 sexual and 45 apomictic entities. Seventeen entities were diploid and 60 were polyploids with different degrees. There were no clear patterns of changes in 1Cx-values due to polyploidy or reproductive systems, and the existing variations are in concordance with subgeneric taxonomical grouping.

The seroprevalence ofTaenia soliumcysticercosis among epileptic patients in León, Nicaragua, as evaluated by ELISA and western blotting

The Taenia solium taeniasis/cysticercosis complex is an important public-health problem in several countries, where many epileptic seizures appear to be associated with neurocysticercosis. As few data on this problem in Nicaragua exist, the seroprevalence of antibodies reacting with antigens from T. solium cysticerci was investigated among 88 Nicaraguan epileptics (45 males and 43 females, aged 6-53 years). In questionnaire-based interviews, each adult subject and a caregiver of each child investigated were asked about potential risk factors for taeniasis/cysticercosis. When a serum sample from each subject was then checked for anti-cysticercus antibodies, 8.0% of the subjects were found seropositive by ELISA and 14.8% by western blotting. Five samples (all from individuals who had been epileptic for > 5 years) were positive in both tests. When the level of association between each potential risk factor and seropositivity (in ELISA or by blotting) was evaluated, the only statistically significant association detected was that between a positive ELISA and the subject living in a household where pigs were raised (odds ratio = 5.18; 95% confidence interval = 0.8-41.6; P = 0.05). The bands most frequently recognized in the western blots (of 50, 42-39, 24 and 14 kDa) were those previously reported. The results indicate that, in the city of Léon, cysticercosis may be endemic and the cause of a significant proportion of the epilepsy recorded.

Using the standard deviation of a region of interest in an image to estimate camera to emitter distance

In this study, a camera to infrared diode (IRED) distance estimation problem was analyzed. The main objective was to define an alternative to measures depth only using the information extracted from pixel grey levels of the IRED image to estimate the distance between the camera and the IRED. In this paper, the standard deviation of the pixel grey level in the region of interest containing the IRED image is proposed as an empirical parameter to define a model for estimating camera to emitter distance. This model includes the camera exposure time, IRED radiant intensity and the distance between the camera and the IRED. An expression for the standard deviation model related to these magnitudes was also derived and calibrated using different images taken under different conditions. From this analysis, we determined the optimum parameters to ensure the best accuracy provided by this alternative. Once the model calibration had been carried out, a differential method to estimate the distance between the camera and the IRED was defined and applied, considering that the camera was aligned with the IRED. The results indicate that this method represents a useful alternative for determining the depth information.

Calibrated serological techniques demonstrate significant different serum response rates to an oral killed cholera vaccine between Swedish and Nicaraguan children

Serum responses to oral cholera vaccines were assessed in three paediatric vaccine trials, two in León, Nicaragua and one in Stockholm, Sweden. A calibrated anti-cholera toxin B subunit (CTB) IgA ELISA was used together with an assay for vibriocidal antibodies. Swedish children had lower pre-vaccination levels of antibody, but serum responses were more pronounced in Swedish children than in Nicaraguan children. Post-vaccination levels of anti-toxin antibody were generally above those found after natural infections with enterotoxigenic Escherichia coli, that cross-reacts serologically with Vibrio cholerae. Adverse events seen after vaccination were generally mild and of little clinical significance.

Effect of pollination timing on the rate of apomictic reproduction revealed by RAPD markers in paspalum notatum

Progeny tests employing molecular markers allow the identification of individuals originated by sexual means among the offspring of a facultative apomict. The objective of this work was to evaluate the effect of the pollination timing on the proportion of sexually formed individuals in progenies of a facultative apomictic Paspalum notatum genotype. Progeny families of approx. 30 plants each were generated at five different pollination times: 1-3 d pre-anthesis; at anthesis; and 2, 4 and 6 d post-anthesis. Cytoembryological analyses indicated that approx. 17% of the ovules carried a meiotic cytologically reduced embryo sac in florets formed simultaneously with those used for crosses. The parental plants and the five F1 families were analysed using RAPD molecular markers. Ninety-five oligonucleotides were assayed on the progenitors in order to search for male-specific bands. Eight primers presenting clear polymorphic bands were selected for use in the progeny tests. The proportion of sexually produced progeny reached 3.4% before anthesis and 20 % at anthesis, while pollination after anthesis generated only maternal plants. A second progeny of 97 plants obtained from pollination at anthesis produced 16 off-type plants (16.5%), of which only one was a B(III) hybrid (2n + n). Our results indicate that pollination at anthesis allows the greatest potential for sexuality to be expressed in this facultative apomictic genotype. When pollination is delayed as soon as 2 d after anthesis, only the aposporous sacs develop endosperm through pseudogamy to set seed.

Evaluating the sensitivity of a subsurface multicomponent reactive transport model with respect to transport and reaction parameters

The input variables for a numerical model of reactive solute transport in groundwater include both transport parameters, such as hydraulic conductivity and infiltration, and reaction parameters that describe the important chemical and biological processes in the system. These parameters are subject to uncertainty due to measurement error and due to the spatial variability of properties in the subsurface environment. This paper compares the relative effects of uncertainty in the transport and reaction parameters on the results of a solute transport model. This question is addressed by comparing the magnitudes of the local sensitivity coefficients for transport and reaction parameters. General sensitivity equations are presented for transport parameters, reaction parameters, and the initial (background) concentrations in the problem domain. Parameter sensitivity coefficients are then calculated for an example problem in which uranium(VI) hydrolysis species are transported through a two-dimensional domain with a spatially variable pattern of surface complexation sites. In this example, the reaction model includes equilibrium speciation reactions and mass transfer-limited non-electrostatic surface complexation reactions. The set of parameters to which the model is most sensitive includes the initial concentration of one of the surface sites, the formation constant (Kf) of one of the surface complexes and the hydraulic conductivity within the reactive zone. For this example problem, the sensitivity analysis demonstrates that transport and reaction parameters are equally important in terms of how their variability affects the model results.

Isolation of cDNA clones differentially expressed in flowers of apomictic and sexual Paspalum notatum

Paspalum notatum is a subtropical forage grass, which reproduces by either sexuality or aposporous gametophytic apomixis. The objective of this work was to identify and isolate mRNA transcripts differentially expressed during the development of the megagametophyte from spikelets of apomictic and sexual P. notatum. Crossing of a sexual mother plant with an apomictic pollen donor generated a progeny family segregating for reproductive mode. Individuals from this F1 family were cytoembryologically classified as sexual or apomictic. Spikelet mRNA compositions from both groups of plants were compared by differential display using an RNA-bulked procedure. Fifty primer combinations were assayed to generate nearly 2,500 total bands in the fingerprints. Three transcripts expressed at higher levels in apomictic plants (apo417, apo398, and apo396) were identified, isolated and cloned. Sequencing showed a high level of homology among the isolated clones. Analysis by RT-PCR Southern blots followed by densitometric studies confirmed that expression reached a level around 30 times higher in apomictic than in sexual individuals and was probably induced at early stages of the megagametophyte development. Genomic DNA from the parental and the F1 progeny plants showed 4-5 bands when hybridised with apo417 in Southern blots. Comparisons to the sequence data banks revealed no identities to genes of known function. However, a putative deduced 3' protein fragment showed homology to the well-characterised KSP multi-phosphorylation domain previously detected in several cdc2-regulated cytoskeletal proteins.

2n+n Hybridization of Apomictic Paspalum dilatatum with Diploid Paspalum Species

Common dallisgrass (Paspalum dilatatum) is an apomictic pentaploid (2n=5x=50) of hybrid origin with irregular meiosis and with the genome formula IIJJX. The I and J genomes are homologous to those of diploid P. intermedium and P. jurgensii, respectively, but the source of the X genome is unknown. Members of the X genome may have genes of special biological significance, including those controlling apomixis. Common dallisgrass was crossed with several diploid Paspalum species in an attempt to identify the source of the X genome. Since common dallisgrass is apomictic, all hybrids produced will be formed by fertilization of an unreduced egg (2n+n). Any hybrid showing 30 chromosome bivalents at meiosis would indicate that the male diploid parent has a chromosome set that is homologous to the X genome of dallisgrass. Over 36,000 spikelets of dallisgrass were emasculated and dusted with pollen of 15 different diploid species (diploid species bearing I or J genomes were excluded). Only five (P. chaseanum, P. equitans, P. fasciculatum, P. notatum, and P. simplex) produced 2n+n hybrids with P. dilatatum. Meiotic chromosome behavior was similar in all hexaploid hybrids showing ca. 20 bivalents and 20 univalents. Results indicated a very low rate of 2n+n hybridization; none of the five diploid species possessed the X genome. Because several diploid species failed to hybridize with 5x dallisgrass, other methods should be attempted. Molecular markers specific for the X genome may help solve the question.

Humoral and cell-mediated immune responses in humans to the NSP4 enterotoxin of rotavirus

Rotavirus nonstructural protein NSP4 has recently been suggested to function as a viral enterotoxin and play a role in the pathophysiological mechanism whereby rotaviruses induce diarrhea. The ability of rotavirus NSP4 to stimulate a humoral immune response was examined in naturally infected children and adults, rotavirus vaccinated children, as well as a cellular immune response in adults. In this study, 10 of 10 naturally infected children and 9 of 10 rotavirus-vaccinated children showed a weak humoral IgG immune response to recombinant NSP4 (rNSP4) and/or a synthetic peptide corresponding to residues 114-134 of NSP4. Modest serum IgG antibody responses were detected in 20 of 20 adults. A cellular immune response to rNSP4 and/or NSP4(114-134) were detected in 8 of 10 adults measured either as a T-cell proliferative response (7 of 10), an increased production of IL-2 (6 of 10), or increased production of interferon-gamma (8 of 10). These results indicate that NSP4 induces a humoral immune response in humans and show for the first time that NSP4 stimulates a cellular immune response, possibly including cytolytic T-cells.

Effects of intracellular calcium on GABAA receptors in mouse cortical neurons

Using the patch-clamp technique, we studied the effect of intracellular Ca2+ on Cl- current gated by type A gamma-aminobutyric acid receptors (GABAA) in mouse cortical neurons. When the rapid Ca2+ chelator 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid (BAPTA) was in the pipette solution, the GABA-activated Cl- current amplitude decreased over time to 49 +/- 7% of control. In contrast, equimolar replacement of BAPTA with ethylenebis(oxonitrilo)tetraacetate (EGTA) caused a 60 +/- 10% increase in GABA current. An increased intracellular Ca2+ concentration caused a transient augmentation of the GABA current. This effect of Ca2+ was concentration dependent (10 nM to 34 muM). Ca2+ increased the amplitude of the current by enhancing the maximal response to GABA rather than by changing the affinity of the receptor to GABA (EC50 = 5 +/- 0.4 muM vs. 7 +/- 0.3 muM). Both calmodulin (CaM) and a CaM kinase II inhibitor (200 muM) blocked the potentiating effect of Ca2+ suggesting that it was mediated by activation of CaM kinase II. We found that regulation of GABAA receptors by intracellular Ca2+ in cortical neurons has important physiological implications since the potentiating effect of increasing the intracellular Ca2+ on responses to GABA was mimicked by activating excitatory receptors with 100 muM N-methyl-D-aspartate (NMDA). These findings suggest that modulation of GABAA receptor activity by glutamate may be brought about via changes in intracellular Ca2+.

Differential intracellular regulation of cortical GABA(A) and spinal glycine receptors in cultured neurons

Using patch-clamp techniques we studied several aspects of intracellular GABA(A) and glycine Cl- current regulation in cortical and spinal cord neurons, respectively. Activation of PKA with a permeable analog of cyclic AMP (cAMP) produced a potentiation of the Cl- current activated with glycine, but not of the current induced with GABA. The inactive analog was without effect. Activation of PKC with 1 microM PMA reduced the amplitude of the GABA(A) and glycine currents. Internal application of 1 mM cGMP, on the other hand, had no effect on the amplitude of either current. The amplitude of these inhibitory currents changed slightly during 20 min of patch-clamp recording. Internal perfusion of the neurons with 1 microM okadaic acid, a phosphatase inhibitor, induced potentiation in both currents. The amplitude of GABA(A) and glycine currents recorded with 1 mM internal CaCl2 and 10 mM EGTA (10 nM free Ca2+) decayed by less than 30% of control. Increasing the CaCl2 concentration to 10 mM (34 microM free Ca2+) induced a transient potentiation of the GABA(A) current. A strong depression of current amplitude was found with longer times of dialysis. The glycine current, on the contrary, was unchanged by increasing the intracellular Ca2+ concentration. Activation of G proteins with internal FAl4- induced an inhibition of the GABA(A) current, but potentiated the amplitude of the strychnine-sensitive Cl- current. These results indicate that GABA(A) and glycine receptors are differentially regulated by activation of protein kinases, G proteins and Ca2+. This conclusion supports the existence of selectivity in the intracellular regulation of these two receptor types.

Rotavirus infections in young Nicaraguan children

BACKGROUND

Rotavirus is an important cause of dehydrating diarrhea in young children throughout the world. Knowledge about frequency of reinfections, development of immunity to the virus and the possible protective effect of breast milk is important, in particular in relation to possible strategies for immunization.

METHODS

A prospective study of rotavirus infections in a cohort of 235 infants followed from birth until 2 years of age was performed in León, Nicaragua. Fecal and serum specimens were collected at specified times, and stools were also obtained during episodes of diarrhea. Fecal specimens were screened by rotavirus antigen detection and serum and colostral specimens were analyzed by isotype-specific rotavirus antibody enzyme-linked immunosorbent assay.

RESULTS

As judged by anti-rotavirus IgA antibody seroconversion and/or demonstration of rotavirus antigen in fecal specimens, > 50% of the babies had evidence of past rotavirus infection by the age of 2 months. The total incidence of rotavirus infections, including many reinfections, was 0.7 infection/child-year, of which only 17% were associated with diarrhea. The time from birth to the first demonstration of rotavirus in stool samples correlated significantly with the concentration of anti-rotavirus IgA antibodies in colostrum. There was also a tendency toward a relationship between long duration of breast-feeding and asymptomatic infection.

CONCLUSIONS

Rotavirus infections are acquired very early in infants in León, Nicaragua, and reinfections are common. Most infections are asymptomatic. Breast milk appears to confer partial protection against rotavirus infection, probably mediated by specific IgA antibodies. To be effective rotavirus vaccination would probably have to be given at a very early age to infants in developing countries.

Analysis of incidence of infection with enterotoxigenic Escherichia coli in a prospective cohort study of infant diarrhea in Nicaragua

Diarrheal episodes with enterotoxigenic Escherichia coli (ETEC) were prospectively monitored during the first 2 years of life in a cohort of 235 infants from Leon, Nicaragua. ETEC was an etiological finding in 38% (310 of 808) of diarrheal episodes and in 19% (277 of 1,472) of samples taken as asymptomatic controls at defined age intervals (P = <0.0001). The majority of diarrheal episodes (80%) occurred before 12 months of age. The major ETEC type was characterized by colonization factor CFA I and elaboration of both heat-labile enterotoxin and heat-stable enterotoxin (ST). The proportion of E. coli strains with CFA I was significantly higher in cases with diarrhea (P = 0.002). The second most prevalent type showed putative colonization factor PCFO166 and production of ST. The prevalence of PCFO166 was approximately 20%, higher than reported before. Children with a first CFA I episode contracted a second ETEC CFA I infection 24% of the time, compared with 46% for ETEC strains of any subtype. Most of the ETEC episodes were of moderate severity, and only 5% (15 of 310) were characterized as severe. In conclusion, our results give valuable information for the planning of intervention studies using ETEC vaccines.

Prevalence and characteristics of severe rotavirus infections in Nicaraguan children

We analyzed the prevalence of rotavirus in 296 children age between 3 and 36 months who were hospitalized in 1994 with severe gastro-enteritis at two health centres for diarrhoea treatment in León, Nicaragua. Enteric viruses were detected in 96 (32.4%) of the children and rotaviruses were the most common pathogens detected in 84 (28%). The majority of rotavirus infections occurred in children less than 1 year old and all strains isolated belonged to subgroup II and had 'long' RNA patterns. Molecular epidemiology of 55 rotavirus strains revealed that all had the same RNA migration pattern and serotyping of 37 strains by PCR technology revealed that all isolates belonged to serotype 3. A significant observation was that only one electropherotype of rotavirus circulated. No non-group A rotaviruses were found by RNA gel electrophoresis. Adenoviruses were found by ELISA in 14 of 265 (5%) children and were most frequently detected during the 1st year of life. Of 103 faecal samples analyzed by electron microscopy, four contained small round structured viruses.

Genital chlamydial infection among women in Nicaragua: validity of direct fluorescent antibody testing, prevalence, risk factors and clinical manifestations

OBJECTIVE

To validate the performance of a direct fluorescence antibody (DFA) test and to determine the prevalence, risk factors and clinical manifestations of cervical chlamydia infection in different groups of women in Nicaragua.

STUDY POPULATION

926 women, 863 routine clinic attenders (mean age 27 years) and 63 sex workers (mean age 25 years) attending health centres in León, Corinto, Matagalpa and Bluefields.

METHODS

Cervical specimens were examined using the Syva MicroTrak test system with a cut-off of 10 or more elementary bodies (EBs). The DFA results were validated by a one-step polymerase chain reaction (PCR) assay. Discordant results were further examined in nested PCR assays directed at two different target genes. An interviewer-administered questionnaire and a standard gynaecological examination were completed.

RESULTS

Sensitivity of DFA was 80.1%, specificity 98.3%, and positive and negative predictive values 62.5% and 99.3%, respectively. Values were lower in locations where samples thawed because of electricity breaks and higher among sex workers. The majority of discordant results was confirmed as positive in nested PCR assays. Prevalence of cervical chlamydia infection based on positivity in DFA and/or PCR ranged from 2% among routine clinic attenders aged 35 years or older, to 8% among adolescent clinic attenders, and to 14% among sex workers. Among routine clinic attenders, young age (odds ratio [OR] 3.6, 95% confidence intervals [95% CI] 1.4-8.9 for women aged 15-19 years as compared with 1 in women 25 years of age or older) and use of oral contraceptives (OR 4.0, 95% CI 1.7-9.6) were the only statistically significant risk factors identified in multivariate logistic regression analysis. Presence of mucopurulent cervical discharge (OR 5.9, 95% CI 3.0-11.5) and presence of ectropion (OR 2.6, 95% CI 1.1-6.5) were the clinical signs independently associated with infection.

CONCLUSIONS

Our results indicate that the DFA test was sensitive and specific while the performance of the PCR assay depends on adequate storage of samples. Genital C trachomatis infection is a common health problem among women in Nicaragua. The wide implementation of syndromic STD management algorithms together with health education programmes aimed at young people is the most promising approach to control STD in Nicaragua.

[Incidence of insulin-dependent diabetes mellitus in the metropolitan region]

We used a retrospective search and confirmation method to establish the number of new cases of insulin dependent diabetes mellitus diagnosed between Jan 1, 1986 and Dec 31, 1989 in subjects under 15 years of age in the Metropolitan region of Chile. All hospitals and outpatient facilities of the National Health Service, other hospitals and private offices of endocrinologists and specialists in diabetes were surveyed, as well as the registry from the Juvenile Diabetes Foundation. A total of 115 cases, 52 in males and 63 in females were found, for an annual incidence of 1.69 and 2.15 per 100,000, respectively. Overall, the annual incidence rates were 2.22 in 1986, 1.22 in 1987 (p < 0.001), 2.13 in 1988 and 2.09 in 1989. A greater number of cases was diagnosed at age 4 in males and at age 12 in females (p < 0.001). The greater number of cases were diagnosed from June to August (winter) and the lowest in October (p < 0.001).

[Treatment of bronchial asthma in winter using controlled-release salbutamol]

This paper presents results about comparative study in winter season, in a statistics design AB and BA on 20 patients that were treated with salbutamol (Group B) and with salbutamol of controlled liberation (Group B) at random. Results showed that patients of Group B had improvement in symptomatology and had less exacerbations than those patients of group A with statistical significance. It was concluded that salbutamol tablets of controlled liberation is a therapeutic method adequate to control chronic phase of asthmatic patients in winter season.

[Role of prostaglandins in the antihypertensive effect of the converting enzyme inhibitor, enalapril]

Angiotensin converting enzyme (ACE) generates angiotensin II and is also capable of degrading bradykinin into inactive peptides. It has been suggested that the effects of ACE inhibitors are partially mediated by increased prostaglandin synthesis induced by a simultaneous rise in bradykinin. Captopril increases PG excretion and indomethacin (INDO) attenuates its effects. Enalapril is a long acting ACE inhibitor, and its molecule does not have the sulphydryl group present in captopril. In order to evaluate the participations of PG in a the ENA effects of enalapril (ENA) on arterial pressure (AP), plasma renin activity (PRA), plasma aldosterone (ALDO) and renal hemodynamics (RH) in essential hypertension (EHT), we compared the effects of ENA alone and associated with INDO. Nine EHT patients received on different occasions: ENA 10 mg, INDO 25 mg and ENA-INDO. Arterial pressure, PGE2, ALDO, PRA, RH and plasma and urinary ENA as enalaprylate were measured after each treatment. Maximal ENA absorption occurred after 4 hours, however it was still detectable after 72 hr. ENA decreased AP after 6 hr in spite of unchanged PGE2 excretion; PRA did not change and ALDO decreased transiently. INDO delayed ENA absorption, slightly attenuated the fall in AP and suppressed PGE2 excretion when given with ENA. INDO alone suppressed PGE2 and did not alter AP. No significant changes occurred in RH with the treatments. Our results suggest that the antihypertensive effect of ENA is independent of PG, and that the slight attenuation induced by INDO may be attributed to a delay in intestinal absorption. In EHT patients under normovolemic conditions, renal function is not altered by ACE inhibition.

[Coronary revascularization in uremic diabetic patients under chronic hemodialysis]

Coronary heart disease is the main cause of mortality among uremic patients on chronic hemodialysis (CHD) and is the determinant of the outcome in these cases after renal transplantation, especially in diabetics. In this study we report our experience with two uremic diabetics on CHD with severe coronary artery lesions in whom aortocoronary bypass was performed before renal transplantation. The outcome in the two patients, after 30 and 55 months respectively indicates successful results. We discuss the necessity to perform coronariography in all the high risk patients on CHD, such as diabetics and elderly before planning renal transplantation and achieve aortocoronary bypass surgery in those with severe coronary disease. The technics and difficulties of the surgery in uremics are also analized.