Nutritional stress compromises mosquito fitness and antiviral immunity, while enhancing dengue virus infection susceptibility

Diet-induced nutritional stress can influence pathogen transmission potential in mosquitoes by impacting life history traits, infection susceptibility, and immunity. To investigate these effects, we manipulate mosquito diets at larval and adult stages, creating two nutritional levels (low and normal), and expose adults to dengue virus (DENV). We observe that egg number is reduced by nutritional stress at both stages and viral exposure separately and jointly, while the likelihood of laying eggs is exclusively influenced by adult nutritional stress. Adult nutritional stress alone shortens survival, while any pairwise combination between both-stage stress and viral exposure have a synergistic effect. Additionally, adult nutritional stress increases susceptibility to DENV infection, while larval nutritional stress likely has a similar effect operating via smaller body size. Furthermore, adult nutritional stress negatively impacts viral titers in infected mosquitoes; however, some survive and show increased titers over time. The immune response to DENV infection is overall suppressed by larval and adult nutritional stress, with specific genes related to Toll, JAK-STAT, and Imd immune signaling pathways, and antimicrobial peptides being downregulated. Our findings underscore the importance of nutritional stress in shaping mosquito traits, infection outcomes, and immune responses, all of which impact the vectorial capacity for DENV transmission.

Insecticidal Activity of Commiphora erythraea Essential Oil and Its Emulsions Against Larvae of Three Mosquito Species

The use of essential oils as ecofriendly tools for vector management is one of the mainstreams for biopesticide research. We evaluated the larvicidal properties of Commiphora erythraea (opoponax) essential oil and its fractions against Culex restuans Theobald, Culex pipiens L., and Aedes aegypti L. The use of bio-based amylose-N-1-hexadecylammonium chloride inclusion complex (Hex-Am) and amylose-sodium palmitate inclusion complex (Na-Palm) as emulsifiers for C. erythraea essential oil was also investigated. Bisabolene was the most abundant chemical constituent in the whole essential oil (33.9%), fraction 2 (62.5%), and fraction 4 (23.8%) while curzerene (32.6%) and α-santalene (30.1%) were the dominant chemical constituents in fractions 1 and 3, respectively. LC50 values for the whole essential oil were 19.05 ppm for Cx. restuans, 22.61 ppm for Cx. pipiens, and 29.83 ppm for Ae. aegypti and differed significantly. None of the four C. erythraea essential oil fractions were active against mosquito larvae. Two CYP450 genes (CYP6M11 and CYP6N12) and one GST gene (GST-2) were significantly upregulated in Ae. aegypti larvae exposed to C. erythraea essential oil suggesting their potential involvement in metabolic pathways for C. erythraea essential oil. Essential oil emulsions produced with Hex-Am were more toxic than the whole essential oil while those produced with Na-Palm had similar toxicity as the whole essential oil. These findings demonstrate that C. erythraea essential oil is a promising source of mosquito larvicide and that the use of Hex-Am as an emulsifier can enhance the insecticidal properties of C. erythraea essential oil.

Study of the epidemiological behavior of malaria in the Darien Region, Panama. 2015-2017

BACKGROUND

Malaria is endemic in Darién and an assessment of the different factors affecting its epidemiology is crucial for the development of adequate strategies of surveillance, prevention, and disease control. The objective of this study was to determine the main characteristics of the epidemiological behavior of malaria in the Darien region.

METHODS

This research was comprised of a retrospective analysis to determine the incidence and malaria distribution in the Darien region from 2015 to 2017. We evaluated malaria indicators, disease distribution, incidence (by age group and sex), diagnostic methods, treatment, and control measures. In addition, we examined the cross-border migration activity and its possible contribution to the maintenance and distribution of malaria.

RESULTS

During the period of 2015-2017, we examined 41,141 thick blood smear samples, out of which 501 tested positive for malaria. Plasmodium vivax was responsible for 92.2% of those infections. Males comprised 62.7% of the total diagnosed cases. Meanwhile, a similar percentage, 62.7%, of the total cases were registered in economically active ages. The more frequent symptoms included fever (99.4%) and chills (97.4%), with 53.1% of cases registering between 2,000 and 6,000 parasites/μl of blood. The annual parasitic incidence (API) average was 3.0/1,000 inhabitants, while the slide positivity rate (SPR) was 1.2% and the annual blood examination rate (ABER) 22.5%. In Darién there is a constant internal and cross-border migration movement between Panama and Colombia. Malaria control measures consisted of the active and passive search of suspected cases and of the application of vector control measures.

CONCLUSION

This study provides an additional perspective on malaria epidemiology in Darién. Additional efforts are required to intensify malaria surveillance and to achieve an effective control, eventually moving closer to the objective of malaria elimination. At the same time, there is a need for more eco-epidemiological, entomological and migratory studies to determine how these factors contribute to the patterns of maintenance and dissemination of malaria.

Host blood-meal source has a strong impact on gut microbiota of Aedes aegypti

Gut microbial communities of mosquitoes can influence vector susceptibility to pathogens, yet the factors that govern their composition remain poorly understood. We investigated the impact of host blood-meal source on gut microbiota of Aedes aegypti L. Adult mosquitoes were fed on human, rabbit or chicken blood and their gut microbiota compared to those of sugar-fed and newly emerged adults. Microbial diversity was significantly reduced in blood-fed and sugar-fed mosquitoes but was restored to the levels of newly emerged adults at 7-days post-blood meal. Microbial composition was strongly influenced by host blood-meal source. Leucobacter spp., Chryseobacterium spp., Elizabethkingia spp. and Serratia spp. were characteristic of newly emerged adults and adults fed on chicken, rabbit and human blood, respectively. Sugar-fed mosquitoes had higher abundance of Pseudomonas spp. and unclassified Acetobacteraceae. Shifts in gut microbial communities in response to host blood-meal source may fundamentally impact pathogen transmission given the well-documented link between specific bacterial taxa and vector susceptibility to a variety of mosquito-borne pathogens and may be a key determinant of individual and population variation in vector competence.

Venezuela's humanitarian crisis, resurgence of vector-borne diseases, and implications for spillover in the region

In the past 5-10 years, Venezuela has faced a severe economic crisis, precipitated by political instability and declining oil revenue. Public health provision has been affected particularly. In this Review, we assess the impact of Venezuela's health-care crisis on vector-borne diseases, and the spillover into neighbouring countries. Between 2000 and 2015, Venezuela witnessed a 359% increase in malaria cases, followed by a 71% increase in 2017 (411 586 cases) compared with 2016 (240 613). Neighbouring countries, such as Brazil, have reported an escalating trend of imported malaria cases from Venezuela, from 1538 in 2014 to 3129 in 2017. In Venezuela, active Chagas disease transmission has been reported, with seroprevalence in children (<10 years), estimated to be as high as 12·5% in one community tested (n=64). Dengue incidence increased by more than four times between 1990 and 2016. The estimated incidence of chikungunya during its epidemic peak is 6975 cases per 100 000 people and that of Zika virus is 2057 cases per 100 000 people. The re-emergence of many vector-borne diseases represents a public health crisis in Venezuela and has the possibility of severely undermining regional disease elimination efforts. National, regional, and global authorities must take action to address these worsening epidemics and prevent their expansion beyond Venezuelan borders.

Bioactivity of Wild Carrot (Daucus carota, Apiaceae) Essential Oil Against Mosquito Larvae

Invasive alien plants wreak havoc on native ecosystems and using them as a source of biopesticides could improve their management. We examined the toxicity of essential oil of wild carrot (also known as 'Queen Anne's Lace', Daucus carota Linnaeus), an aggressive invader throughout the United States, against Aedes aegypti L., Culex pipiens L., and Culex restuans Theobald larvae. Comparisons were made between essential oil extracted from umbels of local populations of wild carrot versus a commercial brand. Methyl isoeugenol (60.7%) was by far the most abundant constituent in commercial brand oil, whereas α-pinene (33.0%) and β-pinene (25.8%) were the dominant constituents in essential oil extracted from local wild carrot populations. The commercial brand essential oil was significantly more toxic to Cx. restuans larvae (LC50 = 44.4 ppm) compared with Cx. pipiens (LC50 = 51.0 ppm) and Ae. aegypti (LC50 = 54.5 ppm). Essential oil from local populations of wild carrot was significantly more toxic to both Cx. pipiens (LC50 = 42.9) and Cx. restuans (LC50 = 40.3) larvae compared with Ae. aegypti (LC50 = 64.6 ppm) larvae. Three of the nine tested chemical constituents of wild carrot essential oil (terpinolene, para cymene, and γ-terpinene) were consistently more toxic to larvae of the three mosquito species than the whole essential oil. These findings suggest that exploiting wild carrot essential oil and its chemical constituents as a biopesticide for mosquito control could be used as part of multifaceted approaches for controlling this invasive alien plant species.

Green, Yellow, and Red Fluorescent Proteins as Markers for Bacterial Isolates from Mosquito Midguts

The growing awareness that microbial symbionts residing in mosquito midguts can interrupt transmission of vector-borne diseases has stimulated interest in understanding their potential role in mosquito biology. Fluorescent proteins are powerful molecular markers that provide for detailed analysis of the function and behavior of specific midgut bacterial isolates without disturbing the normal gut microbiota. The aim of this study was to label bacterial isolates from the midgut of Ochlerotatus triseriatus, the primary vector of La Crosse virus, with green, yellow, and red fluorescent proteins (GFP, YFP, RFP) via electroporation. We also assessed the stability of GFP-, YFP-, and RFP-bearing plasmids and their effect on bacterial growth. Seven of eleven bacterial species could not be labeled despite several attempts. Labeling of Escherichia coli and Enterobacter cloacae was successfully achieved with all three fluorescent proteins. In contrast, labeling of Aerococcus viridans was achieved with GFP only and labeling of Aeromonas hydrophila was achieved with GFP and YFP only. The stability of GFP plasmid varied among bacterial species with A. hydrophila followed by E. cloacae having the most stable GFP label. In contrast, YFP and RFP plasmids were very stable in all bacterial species possessing these labels. GFP plasmid reduced the growth of labeled strains relative to wild type but this effect was not evident in YFP and RFP plasmids. These findings suggest that some mosquito midgut bacterial isolates can effectively be labeled with GFP, YFP and RFP plasmids allowing non-destructive studies on their functions within the vector.

Mosquito microbiota cluster by host sampling location

Background

Microbial communities that inhabit the mosquito body play an import role in host biology and may have potential for mosquito control. However, the forces that shape these microbial communities are poorly understood.

Methods

To gain a better understanding of how host location influences the composition and diversity of mosquito microbiota, we performed a survey of microbial communities in mosquito samples collected from six USA states using HiSeq sequencing of the 16S rRNA gene.

Results

A total of 284 bacterial operational taxonomic units (OTUs) belonging to 14 phyla were detected in nine mosquito species, with Proteobacteria, Firmicutes and Actinobacteria accounting for 95% of total sequences. OTU richness varied markedly within and between mosquito species. The microbial composition and diversity was heavily influenced by the site of mosquito collection, suggesting that host location plays an important role in shaping the mosquito microbiota.

Conclusions

Variation in microbial composition and diversity between mosquitoes from different locations may have important implications on vector competence and transmission dynamics of mosquito-borne pathogens. Future studies should investigate the environmental factors responsible for these variations and the role of key bacteria characterized in this study on mosquito biology and their potential application in symbiotic control of mosquito-borne diseases.

Electronic supplementary material

The online version of this article (10.1186/s13071-018-3036-9) contains supplementary material, which is available to authorized users.

Ovicidal and Larvicidal Effects of Garlic and Asafoetida Essential Oils Against West Nile Virus Vectors

We examined the chemical composition of garlic and asafoetida essential oils and their individual and combined toxicity against larvae of Culex pipiens Linnaeus and Culex restuans Theobald (Diptera: Culicidae). The effect of the two essential oils on egg hatch was also examined. Ten and 12 compounds, respectively, were identified in garlic and asafoetida essential oils. Allyl disulfide (49.13%) and diallyl trisulfide (31.08%) were the most abundant compounds in garlic essential oil accounting for 80.2% of the total oil. In contrast, (E)-sec-butyl propenyl disulfide (30.03%), (Z)-sec-butyl propenyl disulfide (24.32%), and disulfide, methyl 1-(methylthio)propyl (21.87%) were the most abundant compounds in asafoetida essential oil. Allyl disulfide accounted for 7.38% of the total oil in asafoetida essential oil and was one of only three compounds found in both oils. For both mosquito species, garlic essential oil was more toxic than asafoetida essential oil with Cx. restuans (LC50: garlic = 2.7 ppm; asafoetida = 10.1 ppm) being more sensitive than Cx. pipiens (LC50: garlic = 7.5 ppm; asafoetida = 13.5 ppm). When combined, the two essential oils had antagonistic effects. The majority of Culex egg rafts exposed to garlic (73.1%) or asafoetida (55.8%) essential oils failed to hatch and larvae of the few that did hatch mostly died as first instars. Allyl disulfide exhibited strong ovicidal and larvicidal activity suggesting its important contribution to the overall toxicity of the two essential oils. Thus, garlic and asafoetida essential oils are potent mosquito ovicides and larvicides but if used jointly, they could undermine vector control programs.

Comparative Analysis of Gut Microbiota of Culex restuans (Diptera: Culicidae) Females From Different Parents

The potential for gut microbiota to impede or enhance pathogen transmission is well-documented but the factors that shape this microbiota in mosquito vectors are poorly understood. We characterized and compared the gut microbiota of adult females of Culex restuans (Theobald; Diptera: Culicidae) from different parents. Cx. restuans larvae from nine field-collected egg rafts were reared on a common diet and gut microbiota of newly emerged adult females characterized by MiSeq sequencing of the V4 hypervariable region of the 16S rRNA gene. Bacterial diversity and evenness in individuals from one egg raft were significantly lower compared to those of three of the other eight egg rafts. The gut microbiota of adult females reared from seven of the nine egg rafts clustered together suggesting that individuals from most egg rafts had similar profiles of gut microbiota. These findings suggest that the microbiota of adult females from the same parents do not differ appreciably from the microbiota of adult females from different parents. However, additional studies using mosquitoes separated by geographic distances greater than those studied here and estimating the genetic distances between populations from different egg rafts are needed to provide further insights into the influence of host genetics on gut microbiota. Also worthwhile are studies evaluating how individuals from different egg rafts and harboring different gut microbiota compare in relation to vector competence for different pathogens.

Combined Toxicity of Three Essential Oils Against Aedes aegypti (Diptera: Culicidae) Larvae

Essential oils are potential alternatives to synthetic insecticides because they have low mammalian toxicity, degrade rapidly in the environment, and possess complex mixtures of bioactive constituents with multi-modal activity against the target insect populations. Twenty-one essential oils were initially screened for their toxicity against Aedes aegypti (L.) larvae and three out of the seven most toxic essential oils (Manuka, oregano, and clove bud essential oils) were examined for their chemical composition and combined toxicity against Ae. aegypti larvae. Manuka essential oil interacted synergistically with oregano essential oil and antagonistically with clove bud essential oil. GC-MS analysis revealed the presence of 21 components in Manuka essential oil and three components each in oregano and clove bud essential oils. Eugenol (84.9%) and eugenol acetate (9.6%) were the principal constituents in clove bud essential oil while carvacrol (75.8%) and m-isopropyltoluene (15.5%) were the major constituents in oregano essential oil. The major constituents in Manuka essential oil were calamenene (20%) and 3-dodecyl-furandione (11.4%). Manuka essential oil interacted synergistically with eugenol acetate and antagonistically with eugenol, suggesting that eugenol was a major contributor to the antagonistic interaction between Manuka and clove bud essential oils. In addition, Manuka interacted synergistically with carvacrol suggesting its contribution to the synergistic interaction between Manuka and oregano essential oils. These findings provide novel insights that can be used to develop new and safer alternatives to synthetic insecticides.

Comparative analysis of gut microbiota of mosquito communities in central Illinois

Background

The composition and structure of microbial communities that inhabit the mosquito midguts are poorly understood despite their well-documented potential to impede pathogen transmission.

Methodology/Principal findings

We used MiSeq sequencing of the 16S rRNA gene to characterize the bacterial communities of field-collected populations of 12 mosquito species. After quality filtering and rarefaction, the remaining sequences were assigned to 181 operational taxonomic units (OTUs). Approximately 58% of these OTUs occurred in at least two mosquito species but only three OTUs: Gluconobacter (OTU 1), Propionibacterium (OTU 9), and Staphylococcus (OTU 31) occurred in all 12 mosquito species. Individuals of different mosquito species shared similar gut microbiota and it was common for individuals of the same species from the same study site and collection date to harbor different gut microbiota. On average, the microbiota of Aedes albopictus was the least diverse and significantly less even compared to Anopheles crucians, An. quadrimaculatus, Ae. triseriatus, Ae. vexans, Ae. japonicus, Culex restuans, and Culiseta inornata. The microbial community of Cx. pipiens and Ae. albopictus differed significantly from all other mosquitoes species and was primarily driven by the dominance of Wolbachia.

Conclusion and significance

These findings expand the range of mosquito species whose gut microbiota has been characterized and sets the foundation for further studies to determine the influence of these microbiota on vector susceptibility to pathogens.

The microbial communities that reside in mosquito midguts can impact transmission of mosquito-borne pathogens. We used high throughput next generation sequencing to characterize the midgut microbial communities of 12 mosquito species collected in urban residential areas in Champaign County, Illinois. A total of 181 OTUs from 11 phyla and 66 families were identified. Although several bacterial taxa were shared between two or more mosquito species, there was remarkable individual differences in gut microbiota and it was common for individuals of different mosquito species to harbor similar gut microbiota. The microbiota of Ae. albopictus was the least diverse and significantly less evenly distributed compared to 7 of 11 mosquito species. The microbial community of Cx. pipiens and Ae. albopictus differed significantly from other mosquito species and was primarily dominated by Wolbachia. These findings improve current knowledge on the composition and structure of mosquito gut microbiota and provide the framework for understanding their contribution to individual variation in vector competence and potential application in disease control.

Association between fertilizer-mediated changes in microbial communities and Aedes albopictus growth and survival

Contamination of aquatic habitats with anthropogenic nutrients has been associated with an increase in mosquito larval populations but the underlying mechanisms remain poorly understood. We examined the individual and combined effects of two synthetic fertilizers (ammonium sulfate and potassium chloride) on Aedes albopictus survival, development time, and sex ratio. The bacterial and fungal communities of water samples from different fertilizer treatments were also characterized by MiSeq sequencing of the 16S rRNA gene (bacteria) and internal transcribed spacer 1 (fungi) and their relationship with mosquito survival and development determined. Mosquitoes from ammonium sulfate treatment had significantly lower survival rates and longer development times compared to those from control, potassium chloride or a mixture of the two fertilizers. Fertilizer treatment had no significant effects on Ae. albopictus sex ratio although ammonium sulfate treatment tended to be more biased towards males relative to the other treatments. There were no significant effects of fertilizer treatment on fungal communities. However, potassium chloride treatments had lower bacterial diversity compared to the other treatments and the bacterial community structure of control and potassium chloride treatments differed significantly from that of ammonium sulfate and a mixture of the two fertilizers. Microbial composition but not diversity was significantly associated with mosquito survival and development. These findings suggest that anthropogenic nutrients can have a profound impact on mosquito survival and development. In addition to any potential direct effects on mosquito physiology, our results suggest that fertilizers can act indirectly by disrupting the microbial communities that provide a critical food resource for mosquito larvae.

Testing monophyly of the freshwater fish Leporinus (Characiformes, Anostomidae) through molecular analysis

Monophyly of the genus Leporinus (Characiformes: Anostomidae) was tested by sequencing and analysing a total of 4732 bp, including two mitochondrial [cytochrome oxidase subunit 1 (CO1) and cytochrome b (Cytb)] and three nuclear [myosin heavy chain 6 cardiac muscle alpha (Myh6), recombination activating gene 1 (RAG1) and recombination activating gene 2 (RAG2)] loci for 22 species of Leporinus, or c. 25% of all described species in the genus. Phylogenetic tree analyses (maximum parsimony, maximum likelihood and Bayesian species tree) indicate Leporinus to be paraphyletic, with monophyly being rejected by both Kishino-Hasegawa and Shimodaira-Hasegawa tests. The sequenced species of Leporinus are distributed across five clades that are interleaved among other anostomid genera. Several taxonomic changes are suggested as being necessary to restore monophyly for the group. The clade containing the type species, Leporinus fasciatus, should be considered Leporinus sensu stricto and at least three new genera should be described for other species currently considered part of Leporinus.

Abstract LB-239: The Hippo effector YAP promotes resistance to RAF and MEK targeted therapies

Resistance to RAF-MEK targeted therapy is a major clinical challenge. RAF-MEK inhibitors are initially but only transiently effective in some but not all BRAF mutant patients, and largely ineffective in RAS mutant patients because of resistance. Through a genetic screen in BRAF mutant tumor cells, we show that the Hippo pathway effector YAP acts as a parallel survival input to promote resistance to RAF-MEK inhibitor therapy. Combined YAP and RAF-MEK inhibition was synthetically lethal not only in several BRAF mutant tumor types but also in RAS mutant tumors. Increased YAP in BRAFV600E patient tumors was a biomarker of worse initial response to RAF inhibition in patients, establishing the clinical relevance of our findings. Our data uncover YAP as a novel mechanism of resistance to RAF-MEK targeted therapy. The findings unveil the synthetic lethality of YAP and RAF-MEK co-suppression as a promising strategy to enhance response and patient survival.

Citation Format: Luping Lin, Amit Sabnis, Elton Chan, Victor Olivas, Lindsay Cade, Evangelos Pazarentzos, Saurabh Asthana, Dana Neel, Jenny Jiacheng Yan, Xinyuan Lu, Luu Pham, Mingxue Wang, Niki Karachaliou, Maria G. Cao, Jose L. Manzano, Jose L. Ramirez, Jose M. Torres, Fiamma Buttitta, Charles M. Rudin, Eric A. Collisson, Alain Algazi, Eric Robinson, Iman Osman, Eva Munoz-Couselo, Javier Cortes, Dennie T. Frederick, Zachary A. Cooper, Martin McMahon, Antonio Marchetti, Rafael Rosell, Keith T. Flaherty, Jennifer A. Wargo, Trever G. Bivona. The Hippo effector YAP promotes resistance to RAF and MEK targeted therapies. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr LB-239. doi:10.1158/1538-7445.AM2015-LB-239

Two biomarker-directed randomized trials in European and Chinese patients with nonsmall-cell lung cancer: the BRCA1-RAP80 Expression Customization (BREC) studies

BACKGROUND

In a Spanish Lung Cancer Group (SLCG) phase II trial, the combination of BRCA1 and receptor-associated protein 80 (RAP80) expression was significantly associated with outcome in Caucasian patients with nonsmall-cell lung cancer (NSCLC). The SLCG therefore undertook an industry-independent collaborative randomized phase III trial comparing nonselected cisplatin-based chemotherapy with therapy customized according to BRCA1/RAP80 expression. An analogous randomized phase II trial was carried out in China under the auspices of the SLCG to evaluate the effect of BRCA1/RAP80 expression in Asian patients.

PATIENTS AND METHODS

Eligibility criteria included stage IIIB-IV NSCLC and sufficient tumor specimen for molecular analysis. Randomization to the control or experimental arm was 1 : 1 in the SLCG trial and 1 : 3 in the Chinese trial. In both trials, patients in the control arm received docetaxel/cisplatin; in the experimental arm, patients with low RAP80 expression received gemcitabine/cisplatin, those with intermediate/high RAP80 expression and low/intermediate BRCA1 expression received docetaxel/cisplatin, and those with intermediate/high RAP80 expression and high BRCA1 expression received docetaxel alone. The primary end point was progression-free survival (PFS).

RESULTS

Two hundred and seventy-nine patients in the SLCG trial and 124 in the Chinese trial were assessable for PFS. PFS in the control and experimental arms in the SLCG trial was 5.49 and 4.38 months, respectively [log rank P = 0.07; hazard ratio (HR) 1.28; P = 0.03]. In the Chinese trial, PFS was 4.74 and 3.78 months, respectively (log rank P = 0.82; HR 0.95; P = 0.82).

CONCLUSION

Accrual was prematurely closed on the SLCG trial due to the absence of clinical benefit in the experimental over the control arm. However, the BREC studies provide proof of concept that an international, nonindustry, biomarker-directed trial is feasible. Thanks to the groundwork laid by these studies, we expect that ongoing further research on alternative biomarkers to elucidate DNA repair mechanisms will help define novel therapeutic approaches.

TRIAL REGISTRATION

NCT00617656/GECP-BREC and ChiCTR-TRC-12001860/BREC-CHINA.

Relationship between genotypes of the Duffy blood groups and malarial infection in different ethnic groups of Choco, Colombia

INTRODUCTION

The negative homozygous condition for the Duffy blood group (Fy-/Fy-) confers natural resistance to Plasmodium vivax infection. Studies carried out in pursuing this direction in Colombia are scarce.

OBJECTIVE

To describe the relationship between Duffy genotypes in three ethnic communities of La Italia (Chocó) and malarial infection.

METHODS

This is a descriptive, cross-sectional study in symptomatic and asymptomatic subjects with malaria.

SAMPLE SIZE

Afro-Colombians 73; Amerindian (Emberá) 74, and Mestizo, 171. The presence of Plasmodium infection was assessed by thick smear and the status of the Duffy gene was studied by PCR and RFLP to help identify changes to T-46C and A131G which originate the genotypes T/T, T/C , C/C and G/G, G/A, A/A.

RESULTS

Infection by Plasmodium was detected in 17% of cases with 62% due to P. falciparum and 27% due to P. vivax. Duffy genotypes were significantly associated with ethnicity (p= 0.003). Individuals with the C/C, A/A diplotypes were exclusively infected by P. falciparum, whereas the other diplotypes were infected with either of the species. In the Amerindian and Mestizo populations, the frequency of the T-46 allele was 0.90-1.00, among Afro-Colombians this was 0.50, the same as with the C allele and with an absence of heterozygous. At locus 131, the maximum frequency of the G allele was 0.30 in Amerindians and the maximum of the A allele was 0.69 in Afro-Colombians.

CONCLUSIONS

In the Amerindian and mestizo populations studied, there was a predominance of the allele T-46 (FY+) but this was not observed with the P. vivax infection. P. vivax was ruled out in all FY- individuals.

Native microbiota shape insect vector competence for human pathogens

The resident microbiota of insect vectors can impede transmission of human pathogens. Recent studies have highlighted the capacity of endogenous bacteria to decrease viral and parasitic infections in mosquito and tsetse fly vectors by activating their immune responses or directly inhibiting pathogen development. These microbes may prove effective agents for manipulating the vector competence of malaria and other important human pathogens.

Pathogenomics of Culex quinquefasciatus and meta-analysis of infection responses to diverse pathogens

The mosquito Culex quinquefasciatus poses a substantial threat to human and veterinary health as a primary vector of West Nile virus (WNV), the filarial worm Wuchereria bancrofti, and an avian malaria parasite. Comparative phylogenomics revealed an expanded canonical C. quinquefasciatus immune gene repertoire compared with those of Aedes aegypti and Anopheles gambiae. Transcriptomic analysis of C. quinquefasciatus genes responsive to WNV, W. bancrofti, and non-native bacteria facilitated an unprecedented meta-analysis of 25 vector-pathogen interactions involving arboviruses, filarial worms, bacteria, and malaria parasites, revealing common and distinct responses to these pathogen types in three mosquito genera. Our findings provide support for the hypothesis that mosquito-borne pathogens have evolved to evade innate immune responses in three vector mosquito species of major medical importance.

The Toll immune signaling pathway control conserved anti-dengue defenses across diverse Ae. aegypti strains and against multiple dengue virus serotypes

Dengue virus has become one of the most important arboviral pathogens affecting the world today. The virus is transmitted among humans by the mosquitoes Aedes aegypti and Ae. albopictus. Like other vector-borne pathogens, this virus encounters innate immune defenses within the mosquito vector that limit infection. We have previously demonstrated the involvement of the Toll pathway in the anti-dengue defense at 7 days after infection. In the present study, we have investigated the activity of this immune signaling pathway against different dengue virus serotypes at the early stages of infection in laboratory and field-derived mosquito strains. Our studies corroborate the importance of the Toll pathway in the anti-dengue defense repertoire at 3 days after an infectious blood meal, when new virions are released from the midgut for dissemination and infection of other mosquito tissues. These immune defenses are furthermore conserved among different Ae. aegypti strains and can act against a broad range of dengue virus serotypes.

Mosquito infection responses to developing filarial worms

Human lymphatic filariasis is a mosquito-vectored disease caused by the nematode parasites Wuchereria bancrofti, Brugia malayi and Brugia timori. These are relatively large roundworms that can cause considerable damage in compatible mosquito vectors. In order to assess how mosquitoes respond to infection in compatible mosquito-filarial worm associations, microarray analysis was used to evaluate transcriptome changes in Aedes aegypti at various times during B. malayi development. Changes in transcript abundance in response to the different stages of B. malayi infection were diverse. At the early stages of midgut and thoracic muscle cell penetration, a greater number of genes were repressed compared to those that were induced (20 vs. 8). The non-feeding, intracellular first-stage larvae elicited few differences, with 4 transcripts showing an increased and 9 a decreased abundance relative to controls. Several cecropin transcripts increased in abundance after parasites molted to second-stage larvae. However, the greatest number of transcripts changed in abundance after larvae molted to third-stage larvae and migrated to the head and proboscis (120 induced, 38 repressed), including a large number of putative, immunity-related genes (∼13% of genes with predicted functions). To test whether the innate immune system of mosquitoes was capable of modulating permissiveness to the parasite, we activated the Toll and Imd pathway controlled rel family transcription factors Rel1 and Rel2 (by RNA interference knockdown of the pathway's negative regulators Cactus and Caspar) during the early stages of infection with B. malayi. The activation of either of these immune signaling pathways, or knockdown of the Toll pathway, did not affect B. malayi in Ae. aegypti. The possibility of LF parasites evading mosquito immune responses during successful development is discussed.

Filarial worms that cause human lymphatic filariasis (LF) are transmitted by many species of mosquitoes. Within susceptible mosquitoes, Brugia malayi develop from microfilariae (mf) to infective-stage larvae (L3s), in approximately eight days. These nematodes develop as intracellular parasites within mosquito flight muscle cells, in which they ingest cellular material and eventually cause cell death when L3s migrate to the mosquito's proboscis. We examined the effects of B. malayi parasitism on Aedes aegypti by analyzing changes in mosquito gene expression at different stages of parasite development. We found that a few genes were differentially expressed at the RNA level relative to non-infected controls. The majority of changes occurred at two time periods, when the filarial worms began feeding and when the L3s were in the head and proboscis. Many transcriptional changes in the later group concur with documented descriptions of tissue damage, clean-up and repair that occurs in mosquitoes infected with filarial worms. In addition, we activated two innate immunity signaling pathways and observed the effects on filarial worm development. B. malayi seems to be capable of evading these immune responses, because its development was not impeded by the activation of either the Toll or Imd signal pathways in Ae. aegypti.

The Aedes aegypti toll pathway controls dengue virus infection

Aedes aegypti, the mosquito vector of dengue viruses, utilizes its innate immune system to ward off a variety of pathogens, some of which can cause disease in humans. To date, the features of insects' innate immune defenses against viruses have mainly been studied in the fruit fly Drosophila melanogaster, which appears to utilize different immune pathways against different types of viruses, in addition to an RNA interference-based defense system. We have used the recently released whole-genome sequence of the Ae. aegypti mosquito, in combination with high-throughput gene expression and RNA interference (RNAi)-based reverse genetic analyses, to characterize its response to dengue virus infection in different body compartments. We have further addressed the impact of the mosquito's endogenous microbial flora on virus infection. Our findings indicate a significant role for the Toll pathway in regulating resistance to dengue virus, as indicated by an infection-responsive regulation and functional assessment of several Toll pathway-associated genes. We have also shown that the mosquito's natural microbiota play a role in modulating the dengue virus infection, possibly through basal-level stimulation of the Toll immune pathway.

Detection of the bacterium, Xylella fastidiosa, in saliva of glassy-winged sharpshooter, Homalodisca vitripennis

Homalodisca vitripennis (Germar) (Hemiptera: Cicadellidae), the glassy-winged sharpshooter, is one of the most important vectors of the bacterium, Xylella fastidiosa subsp. piercei (Xanthomonadales: Xanthomonadaceae) that causes Pierce's Disease in grapevines in California. In the present study we report a new method for studying pathogen transmission or probing behavior of H. vitripennis. When confined, H. vitripennis attempt to probe the surface of sterile containers 48 hours post-acquisition of X. f. piercei. The saliva deposited during attempted feeding probes was found to contain X. f. piercei. We observed no correlation between X. f. piercei titers in the foregut of H. vitripennis that fed on Xylella-infected grapevines and the presence of this bacterium in the deposited saliva. The infection rate after a 48 h post-acquisition feeding on healthy citrus and grapevines was observed to be 77% for H. vitripennis that fed on grapevines and 81% for H. vitripennis that fed on citrus, with no difference in the number of positive probing sites from H. vitripennis that fed on either grapevine or citrus. This method is amenable for individual assessment of X. f. piercei-infecuvity, with samples less likely to be affected by tissue contamination that is usually present in whole body extracts.

In silico, biologically-inspired modelling of genomic variation generation in surface proteins of Trypanosoma cruzi

BACKGROUND

Protozoan parasites improve the likelihood of invading or adapting to the host through their capacity to present a large repertoire of surface molecules. The understanding of the mechanisms underlying the generation of antigenic diversity is crucial to aid in the development of therapies and the study of evolution. Despite advances driven by molecular biology and genomics, there is a need to gain a deeper understanding of key properties that may facilitate variation generation, models for explaining the role of genomic re-arrangements and the characterisation of surface protein families on the basis of their capacity to generate variation. Computer models may be implemented to explore, visualise and estimate the variation generation capacity of gene families in a dynamic fashion. In this paper we report the dynamic simulation of genomic variation using real T. cruzi coding sequences as inputs to a computational simulation system. The effects of random, multiple-point mutations and gene conversions on genomic variation generation were quantitatively estimated and visualised. Simulations were also implemented to investigate the potential role of pseudogenes as a source of antigenic variation in T. cruzi.

RESULTS

Computational models of variation generation were applied to real coding sequences from surface proteins in T. cruzi: trans-sialidase-like proteins and putative surface protein dispersed gene family-1. In the simulations the sequences self-replicated, mutated and re-arranged during thousands of generations. Simulations were implemented for different mutation rates to estimate the relative robustness of the protein families in the face of DNA multiple-point mutations and sequence re-arrangements. The gene super-families and families showed distinguishing evolutionary responses, which may be used to characterise them on the basis of their capacity to generate variability. The simulations showed that sequences from T. cruzi nuclear genes tend to be relatively more robust against random, multiple-point mutations than those obtained from surface protein genes. Simulations also showed that a gene conversion model may act as an effective variation generation mechanism. Differential variation responses can be used to characterise the sequence groups under study. For example, unlike other families, sequences from the DGF1 family have the capacity to maximise variation at the amino acid level under relatively low mutation rates and through gene conversion. However, in relation to the other protein families, they exhibit more robust behaviour in response to more severe modifications through intra-family genomic sequence exchange. Independent simulations indicate that DGF1 pseudogenes might play a role in the generation of greater genomic variation in the DFG1 gene family through gene conversion under different experimental conditions.

CONCLUSION

Digital, dynamic simulations may be implemented to characterise gene families on the basis of their capacity to generate variation in the face of genomic perturbations. Such simulations may be useful to explore antigenic variation mechanisms and hypotheses about robustness at the genomic level. This investigation illustrated how sequences derived from surface protein genes and computer simulations can be used to investigate variation generation mechanisms. Such in silico experiments of self-replicating sequences undergoing random mutations and genomic re-arrangements can offer insights into the diversity generation potential of the genes under study. Biologically-inspired simulations may support the study of genomic variation mechanisms in pathogens whose genomes have been recently sequenced.

Endoscopic Approach for Mandibular Orthognathic Surgery

The field of minimally invasive surgery is defined as the combination of surgical innovation with modern technology. This article describes the history of surgery and newer developments in endoscopic surgery for mandibular orthognathic surgery.

Link between primary and secondary metabolism in the biotransformation of trimethylammonium compounds by escherichia coli

The aim of this work was to understand the steps controlling the process of biotransformation of trimethylamonium compounds into L(-)-carnitine by Escherichia coli and the link between the central carbon or primary and the secondary metabolism expressed. Thus, the enzyme activities involved in the biotransformation process of crotonobetaine into L(-)-carnitine (crotonobetaine hydration reaction and crotonobetaine reduction reaction), in the synthesis of acetyl-CoA (pyruvate dehydrogenase, acetyl-CoA synthetase, and ATP:acetate phosphotransferase) and in the distribution of metabolites for the tricarboxylic acid (isocitrate dehydrogenase) and glyoxylate (isocitrate lyase) cycles, were followed in batch with both growing and resting cells and during continuous cell growth in stirred-tank and high-cell-density membrane reactors. In addition, the levels of carnitine, crotonobetaine, gamma-butyrobetaine, ATP, NADH/NAD(+), and acetyl-CoA/CoA ratios were measured to determine how metabolic fluxes were distributed in the catabolic system. The results provide the first experimental evidence demonstrating the important role of the glyoxylate shunt during biotransformation of resting cells and the need for high levels of ATP to maintain metabolite transport and biotransformation (2.1 to 16.0 mmol L cellular/mmol ATP L reactor h). Moreover, the results obtained for the pool of acetyl-CoA/CoA indicate that it also correlated with the biotransformation process. The main metabolic pathway operating during cell growth in the high cell-density membrane reactor was that related to isocitrate dehydrogenase (during start-up) and isocitrate lyase (during steady-state operation), together with phosphotransacetylase and acetyl-CoA synthetase. More importantly, the link between central carbon and L(-)-carnitine metabolism at the level of the ATP pool was also confirmed.

Serum DNA as a tool for cancer patient management

PURPOSE

Genetic analysis has shown that cell-free circulating DNA in plasma or serum of cancer patients shares similar genetic alterations to those described in the corresponding tumor. One of the most important alterations involved in carcinogenesis is aberrant promoter methylation. The interest in this field has grown due to the implementation of the methylation-specific PCR (MSP) assay. The main objective of this study is to analyze the methylation status of different genes in tumor and serum DNA obtained at the time of surgery in two different tumor models (glioblastoma [GBM] and non-small-cell lung cancer [NSCLC]) and their relationship to clinico-pathological characteristics and response to chemotherapy.

MATERIAL AND METHODS

Using MSP assay, we assessed the methylation status of MGMT, RASSF1A, p16, DAPK, TMS-1 in tumor and serum DNA obtained at time of surgery or stereotactic biopsy from 28 GBM patients and from 51 NSCLC patients.

RESULTS

In GBM patients, the prevalence of MGMT, p16, DAPK, and RASSF1A promoter methylation was 38.1%, 66.7%, 52.4%, 57.1%, respectively, in glioma tissue, and 39.3%, 53.6%, 34.3%, 50%, respectively, in serum. A high correlation between methylation in tumor and serum (Spearman test p = 0.0001) was observed. In NSCLC patients, RASSF1A, DAPK and TMS-1 were methylated in 34%, 45% and 35% tumors, respectively, and in 34%, 40% and 34% serum, respectively. A good correlation was found between alterations found in tumor and serum (Spearman test p = 0.0001).

CONCLUSIONS

The study of serum or plasma DNA has opened new roads for translational research and new strategies for molecular diagnosis. Due to the similarities of alterations found in serum DNA and primary tumor, we can use this tool to calculate the risk of local or distant recurrence and its relationship with survival and its value in patient follow-up to evaluate response to therapy.

Influences of parity and level of feed intake on reproductive response to insulin administration after weaning in sows

In three experiments, the influence of insulin administered after weaning was examined in primiparous sows given extra feed or in primiparous compared to multiparous sows. In Exp. 1, 171 primiparous and 231 multiparous crossbred sows on a commercial farm were injected with 0.4 IU/kg BW insulin (Eli Lilly Lente Iletin II) or saline for 4 d beginning the day after weaning (d 0) and were fed 2.3 kg/d until mating. In Exp. 2, 153 primiparous sows from the same farm as those in Exp. 1 were injected with insulin or saline as in Exp. 1 and were fed 2.7 or 3.6 kg/d until mating. In Exp. 3, 63 primiparous crossbred sows were injected with insulin or saline as described above and fed either 2.3 or 4.5 kg/d for 5 d after weaning and were remated. On the commercial farm (Exp. 1 and 2), insulin administration increased percentage in estrus for primiparous sows compared to multiparous sows (treatment x parity interaction, P < 0.02) but tended to lower litter size in primiparous sows (treatment x parity interaction, P < 0.06). In Exp. 2, insulin combined with extra feed increased (P < 0.05) litter size by two pigs but tended (P < 0.07) to decrease farrowing rate in that group (treatment x feed interaction). Weaning-to-estrus interval, pregnancy rate, ovulation rate, and embryo survival were not influenced by treatment or feeding level (Exp. 3); however, postweaning intake and embryo survival were negatively related for saline-treated sows only (r = -0.55; P < 0.01), and backfat depth at weaning and embryo survival were positively related for insulin-treated sows only (r = 0.44; P < 0.05). Overall, insulin administration differentially influenced reproduction in primiparous sows and may have interacted with metabolic or nutritional state of the animal.

PCR detection of specific Leishmania-DNA in patients with periodontal disease

This study deals with the detection of Leishmania braziliensis DNA in gingival specimens from 10 individuals who all had suffered from cutaneous leishmaniasis 5-10 years prior to the examination and all had been treated with anti-leishmaniasis drugs. This preliminary study gives an interesting contribution to the oral microbiology of this disease, with the observation that inflamed periodontal tissues can serve as a factor affecting the dispersion of Leishmania parasites in individuals who had suffered from cutaneous leishmaniasis. These finding are corroborated by the results of polymerase chain reaction (PCR) which demonstrated the presence of Leishmania DNA in tissue samples of patients with periodontal diseases.

Detection and significance of inapparent infection in Chagas disease in western Venezuela

Inapparent infections of Trypanosoma cruzi were detected in symptomless seropositive people living in close proximity, and under the same conditions of risk, to patients with acute Chagas disease. Similar infections were also detected in sera samples of people from 25 villages of western Venezuela where Chagas disease is endemic. Seropositivity in all the 1,251 studied samples was established by use of 3 serological methods (direct agglutination test, indirect immunofluorescence antibody test, and enzyme-linked immunosorbent assay). Each seropositive sample was tested for detection of anti-T. cruzi-specific immunoglobulin (Ig) M and IgG levels and specific T. cruzi infection by molecular methodology (polymerase chain reaction assay). The combined analysis of the serologic (IgM and IgG levels), molecular (specific T. cruzi DNA), and statistical findings demonstrated the existence of a different stage of T. cruzi infection in asymptomatic patients, which is suggested to be recognized as inapparent infection. Its definition, significance, and comparison with typical Chagas disease phases are presented, and its potential epidemiological importance is discussed.

High risk human papillomavirus in oral squamous carcinoma: evidence of risk factors in a Venezuelan rural population. Preliminary report

In a search for the presence of human papillomavirus (HPV) and some etiologic cofactors in oral squamous cell carcinoma (OSCC), 50 women diagnosed as OSCC were analyzed by a multiplex polymerase chain reaction (PCR) assay specific for HPV types 6, 11, 16, and 18. This study revealed that 60% (30/50) of the OSCC patients were positive for HPV-DNA sequences. This group was analyzed according to smoking, alcohol consumption, number of pregnancies, poor oral health and low social economic status. The current results indicate an increased incidence of HPV malignant types in the oral cavity in women with OSCC. Also, they support a multifactorial model of oral cancer causation.

Correlation between serum levels of 17 beta-estradiol, progesterone and beta-human chorionic gonadotropin and the karyotype of first trimester anembryonic and embryonic pregnancies

We aimed at establishing the correlation between karyotype of anembryonic and embryonic first trimester pregnancies and serum levels of beta-hCG, 17beta-estradiol and progesterone. Chromosomal analyses were performed on products of conceptions lower than 12 weeks, using standard-banding protocols. Measurements of 17beta-estradiol and progesterone were carried out by immunoenzymatic assays and beta-hCG by radioimmunoanalysis (RIA). Chromosomal analyses among 11 spontaneous abortions revealed 6 (54,5%) to be normal and 5 (45,5%) abnormal; of these latter, 4 were anembryonic pregnancies (44,4% total frequency). Serum beta hCG and beta-estradiol average levels were lower in the anembryonic pregnancies but did not reveal significant differences with normal levels. Hormonal levels were correlated with karyotype results and it was found that average beta-hCG value was 3.8 times higher in cases with abnormal karyotype than in those in whom it was normal (p <0.05). Linear correlation analyses between hormonal measurements in anembryonic pregnancies were statistically significant (p <0.05). Correlations between beta-hCG and progesterone, beta-hCG and 17-beta estradiol, and the latter with progesterone, proved to be significant in the group with abnormal karyotype (p < 0.05). Anembryonic pregnancies present high frequency of chromosomal anomalies; such pregnancies with abnormal karyotype have a high serum level of beta-hCG; this condition increased the rate of abortion.

Somatostatin is required for masculinization of growth hormone-regulated hepatic gene expression but not of somatic growth

Pulsatile growth hormone (GH) secretion differs between males and females and regulates the sex-specific expression of cytochrome P450s in liver. Sex steroids influence the secretory dynamics of GH, but the neuroendocrine mechanisms have not been conclusively established. Because periventricular hypothalamic somatostatin (SST) expression is greater in males than in females, we generated knockout (Smst(-/-)) mice to investigate whether SST peptides are necessary for sexually differentiated GH secretion and action. Despite marked increases in nadir and median plasma GH levels in both sexes of Smst(-/-) compared with Smst(+/+) mice, the mutant mice had growth curves identical to their sibling controls and retained a normal sexual dimorphism in weight and length. In contrast, the liver of male Smst(-/-) mice was feminized, resulting in an identical profile of GH-regulated hepatic mRNAs between male and female mutants. Male Smst(-/-) mice show higher expression of two SST receptors in the hypothalamus and pituitary than do females. These data indicate that SST is required to masculinize the ultradian GH rhythm by suppressing interpulse GH levels. In the absence of SST, male and female mice exhibit similarly altered plasma GH profiles that eliminate sexually dimorphic liver function but do not affect dimorphic growth.

Green fluorescent protein-tagged Leishmania in phlebotomine sand flies

In this work we have used for the first time green fluorescent protein (GFP) tagged cells of the human parasite Leishmania donovani to observe its development in the gut of phlebotomine sand flies. Low numbers of GFP-tagged L. donovani were more easily detected than nontagged Leishmania, suggesting that GFP-tagged Leishmania could be used to efficiently study the biology of Leishmania in their vectors, and open the possibility of using nonaxenic flies. Using this method, we found that GFP-tagged L. donovani, the ethiological agent of Old World Kala-azar, were able to establish an infection within the gut of Lutzomyia species, which are vectors of New World Leishmania. The GFP-tagged parasites divide successfully in the gut of colonized and in wild caught Lu. longipalpis (Lutz & Neiva, 1912), Lu. ovallesis (Ortiz, 1952), and Lu. youngi (Feliciangeli & Murillo, 1985). In the case of Lulongipalpis the labeled parasite exhibited a normal anterior development as the one observed in its natural vector.

Cloning and characterization of Leishmania donovani telomeres

We describe here the cloning and sequence characterization of the absolute termini of several telomeres from the human parasite Leishmania donovani using a vector-adapter protocol. The 3' protruding strand of L. donovani telomeres terminates with the sequence 5'-GGTTAGGGT-OH 3'. This single-stranded sequence is adjacent to tandemly repeated blocks of double-stranded sequence consisting of variable numbers of the hexameric repeat 5'-TAGGGT-3', variable numbers of an octameric repeat 5'-TGGTCATG-3', and a single 62-bp sequence, in that order. A number of additional, more chromosome-internal, nonrepeated sequences were found adjacent to the telomere sequences. Hybridization analyses indicated that some of these telomere adjacent sequences are found on all L. donovani chromosomes, some are more abundant on certain subsets of chromosomes, and some are unique to individual chromosomes.

Physical mapping of a 670-kb region of chromosomes XVI and XVII from the human protozoan parasite Trypanosoma cruzi encompassing the genes for two immunodominant antigens

As part of the Trypanosoma cruzi Genome Initiative, we have mapped a large portion of the chromosomal bands XVI (2.3 Mb) and XVII (2.6 Mb) containing the highly repetitive and immunodominant antigenic gene families h49 and jl8. Restriction mapping of the isolated chromosomal bands and hybridization with chromosome specific gene probes showed that genes h49 and jl8 are located in a pair of size-polymorphic homologous chromosomes. To construct the integrated map of the chromosomes harboring the h49 and jl8 loci, we used YAC, cosmid, and lambda phage overlapping clones, and long range restriction analysis using a variety of probes (i.e., known gene sequences, ESTs, polymorphic repetitive sequences, anonymous sequences, STSs generated from the YAC ends). The total length covered by the YAC contig was approximately 670 kb, and its map agreed and was complementary to the one obtained by long-range restriction fragment analysis. Average genetic marker spacing in a 105 kb region around h49 and jl8 genes was estimated to be 6.2 kb/marker. We have detected some polymorphism in the H49/JL8 antigens-encoding chromosomes, affecting also the coding regions. The physical map of this region, together with the isolation of specific chromosome markers, will contribute in the global effort to sequence the nuclear genome of this parasite.

Organization of telomeric and sub-telomeric regions of chromosomes from the protozoan parasite Trypanosoma cruzi

We present here a characterization of the telomeric and subtelomeric regions of Trypanosoma cruzi chromosomes, using three types of recombinants: cosmids from a genomic library, clones obtained by a vector-adaptor protocol, and a recombinant fragment cloned by a Bal31 trimming protocol. The last nine nucleotides of the T. cruzi overhang are 5'-GGGTTAGGG-3', and there are from 9 to 50 copies of the hexameric repeat 5'-TTAGGG-3', followed by a 189-bp junction sequence common to all recombinants. The subtelomeric region is made of sequences associated with the gp85/sialidase gene family, and/or sequences derived from SIRE, a retrotransposon-like sequence, and also the retrotransposon L1Tc. We discuss the possible implications of this genome organization.

Myocardial parasite persistence in chronic chagasic patients

The persistence of Trypanosoma cruzi tissue forms was detected in the myocardium of seropositive individuals clinically diagnosed as chronic chagasic patients following endomyocardial biopsies (EMBs) processed by immunohistochemical (peroxidase-anti-peroxidase [PAP] staining) and molecular (polymerase chain reaction [PCR]) techniques. An indirect immunofluorescent technique revealed antigenic deposits in the cardiac tissue in 24 (88.9%) of 27 patients. Persistent T. cruzi amastigotes were detected by PAP staining in the myocardium of 22 (84.6%) of 26 patients. This finding was confirmed with a PCR assay specific for T. cruzi in 21 (91.3%) of 23 biopsy specimens from the same patients. Statistical analysis revealed substantial agreement between PCR and PAP techniques (k = 0.68) and the PCR and any serologic test (k = 0.77). The histopathologic study of EMB specimens from these patients revealed necrosis, inflammatory infiltrates, and fibrosis, and made it possible to detect heart abnormalities not detected by electrocardiogram and/or cineventriculogram. These indications of myocarditis were supported by the detection of T. cruzi amastigotes by the PAP technique or its genome by PCR. They suggest that although the number of parasites is low in patients with chronic Chagas' disease, their potential for heart damage may be comparable with those present during the acute phase. The urgent necessity for testing new drugs with long-term effects on T. cruzi is discussed in the context of the present results.

Acute Chagas' disease in western Venezuela: a clinical, seroparasitologic, and epidemiologic study

A clinical, parasitologic, and serologic study carried out between 1988 and 1996 on 59 acute-phase patients in areas of western Venezuela where Chagas' disease is endemic showed 19 symptomatic patterns or groups of symptoms appearing in combination with different frequencies. The symptomatic pattern with the highest frequency was that showing simultaneously fever, myalgia, headache, and Romaña's sign, which was detected in 20% of the acute-phase patients. Asymptomatic individuals and patients with fever as the only sign of the disease made up 15% and 11.9% of the total acute cases, respectively. Statistical correlation analysis revealed that xenodiagnosis and hemoculture were the most reliable and concordant of the five parasitologic methods used; these two methods also showed the highest proportions in detecting any clinical symptomatic pattern in acute-phase patients. A similar high reliability and concordance was obtained with a direct agglutination test, an indirect immunofluorescent antibody test, and an ELISA as serologic tests, which also showed a higher proportion of positive detection of clinical patterns than parasitologic methods (P < 0.001). It is recommended that individuals coming from endemic areas showing mild and/or severe clinical manifestations should be suspected of being in contact or having been in contact with Trypanosoma cruzi, be referred for parasitologic and serologic evaluations to confirm the presumptive clinical diagnosis of acute Chagas' disease, and start specific treatment. The epidemiologic implications of the present findings are discussed and the use of similar methodology to evaluate other areas where Chagas' disease is endemic is suggested.

Evaluation of DNA recombinant methodologies for the diagnosis of Plasmodium falciparum and their comparison with the microscopy assay

Since 1984, DNA tests based on the highly repeated subtelomeric sequences of Plasmodium falciparum (rep 20) have been frequently used in malaria diagnosis. Rep 20 is very specific for this parasite, and is made of 21 bp units, organized in repeated blocks with direct and inverted orientation. Based in this particular organization, we selected a unique consensus oligonucleotide (pf-21) to drive a PCR reaction coupled to hybridization to non-radioactive labeled probes. The pf-21 unique oligo PCR (pf-21-I) assay produced DNA amplification fingerprints when was applied on purified P. falciparum DNA samples (Brazil and Colombia), as well as in patient's blood samples from a large area of Venezuela. The performance of the Pf-21-I assay was compared against Giemsa stained thick blood smears from samples collected at a malaria endemic area of the Bolivar State, Venezuela, at the field station of Malariología in Tumeremo. Coupled to non-radioactive hybridization the pf-21-I performed better than the traditional microscopic method with a r = 1.7:1. In the case of mixed infections the r value of P. falciparum detection increased to 2.5:1. The increased diagnostic sensitivity of the test produced with this homologous oligonucleotide could provide an alternative to the epidemiological diagnosis of P. falciparum being currently used in Venezuela endemic areas, where low parasitemia levels and asymptomatic malaria are frequent. In addition, the DNA fingerprint could be tested in molecular population studies.

Transrectal ultrasonography: relationship with anorectal manometry, electromyography and sensitivity tests in irritable bowel syndrome

Irritable bowel syndrome is the most frequently diagnosed disorder in gastroenterology. It has been demonstrated with specialized motility studies that these patients compared to healthy subjects show changes in rectoanal electrical and mechanical activity and in rectoanal sensitivity. However, until now no report has been published on morphological alterations in the rectum or the internal anal sphincter. Twenty-five consecutive patients with irritable bowel syndrome (mean age 32, range 17-47 years; 24 females) were evaluated prospectively by transrectal ultrasonography, rectal sensitivity studies, and recordings of both electrical and mechanical activity of the distal rectum and internal anal sphincter during a 2-h inter-digestive period. Ten healthy volunteers (mean age 34.5, range 19-50 years) served as a control group. Paired and non-paired Student's two-tailed t test and linear regression analysis were used. It was shown that muscle thickness of the rectum during rest (4.7 +/- 0.1 mm) was correlated neither with its rectal spike amplitude (0.73 +/- 0.1 mV) nor with rectal spike frequency (17.06 +/- 3.6 spike/2 h). In addition, the diameter of the internal anal sphincter (1.2 +/- 0.1 mm) was correlated neither with its resting pressure, nor with frequency (17.1 +/- 3.2/2 h), duration (14.9 +/- 1.5 s), or amplitude (14.1 +/- 1.9 mmHg), of inhibition of the spontaneous rectoanal inhibitory reflex. No correlation was found between ultrasonographic parameters and rectal distension variables (r = 0.03). This study demonstrates for the first time morphological anorectal changes in patients with irritable bowel syndrome compared to healthy subjects, in addition to showing that morphological changes are independent of physiological ones. Therefore both transrectal ultrasonography to determine anorectal morphology and electromanometry to assess anorectal function are important measures in the evaluation of patients with irritable bowel syndrome.

Characterization of an interspersed repetitive DNA element in the genome of Trypanosoma cruzi

We report the molecular characterization of a middle repetitive DNA sequence, named C6, isolated from the Trypanosoma cruzi genome. C6 appears to be a composite repeated element since 3 subregions may be defined within it on the basis of sequence similarities with other T. cruzi genomic sequences. Sequences homologous to C6 are interspersed in the genome and can be mapped out on most chromosomal bands of different T. cruzi. strains. The copy number of the C6 element is about 1000 per haploid genome. Given the species specificity and different genomic distribution of C6 homologous sequences among the T. cruzi strains the C6 element could be a useful probe for diagnosis and typing of parasites. C6 is a polymorphic marker with potential as a tool for physical mapping of the T. cruzi genome.

The Trypanosoma cruzi genome project: nuclear karyotype and gene mapping of clone CL Brener

By using improved pulsed field gel electrophoresis conditions, the molecular karyotype of the reference clone CL Brener selected for Trypanosoma cruzi genome project was established. A total of 20 uniform chromosomal bands ranging in size from 0.45 to 3.5 Megabase pairs (Mbp) were resolved in a single run. The weighted sum of the chromosomal bands was approximately 87 Mbp. Chromoblots were hybridized with 39 different homologous probes, 13 of which identified single chromosomes. Several markers showed linkage and four different linkage groups were identified, each comprising two markers. Densitometric analysis suggests that most of the chromosomal bands contain two or more chromosomes representing either homologous chromosomes and/or heterologous chromosomes with similar sizes.

Influence of exogenous insulin before breeding on conception rate and litter size of sows

We conducted two experiments on commercial farms to evaluate the effect of insulin administered to primiparous sows before postweaning estrus on subsequent reproductive performance. On the day after weaning in Exp. 1, 138 crossbred primiparous sows were assigned to receive saline or insulin (.4 IU/kg BW) once daily at the time of feeding for four consecutive days. Treatment did not affect interval from weaning to estrus (5.1 +/- .2 d) or percentage in estrus by 7 d after weaning (92.6%). Farrowing rate at second parity was increased by insulin (76.7 and 92.3% for saline and insulin treatments, respectively; P < .01). Litter sizes at second parity were not affected by insulin treatment. Experiment 2 was conducted on a different commercial farm using 491 primiparous crossbred sows. They were treated similarly to those in Exp. 1 with saline or insulin after weaning, except that treatment duration of 2 d of saline or insulin was included. Treatment did not affect the interval from weaning to estrus (overall, 9.2 +/- .5 d), percentage in estrus by 7 d after weaning (79.1%) or farrowing rate (90.2%). However, the number of total pigs born in the second litter for sows mated within 7 d after weaning was increased (P < .05) by one pig in sows treated with insulin for 4 d (10.3 +/- .3 pigs) compared with 2 d (9.1 +/- .3) and with saline (2 d and 4 d grouped together: 9.3 +/- .1). Third-parity litter size was not adversely affected by treatments applied before the second litter. In conclusion, manipulation with a metabolic hormone such as insulin may improve postweaning fertility by affecting aspects of ovarian follicle development or pregnancy establishment.

Defaecography in patients with irritable bowel syndrome and healthy volunteers

BACKGROUND

In patients with IBS, many symptoms have their origin in the recto-anal segment, with motility changes in the rectum and in the internal anal sphincter, and alterations in rectal sensitivity. However, up to now, it is not known if these clinical and physiological changes are equated with morphological changes in the recto-anal segment.

METHODS

Sixteen consecutive patients with IBS (mean age 22, range 18-33 years; 13 females) and 10 healthy volunteers (mean age 34.5, range 19-50 yr.; 6 males) were evaluated prospectively with defaecography.

RESULTS

1) Anorectal angle: No significant differences were observed in the anorectal angle during rest (91.6 +/- 3.5 degrees vs 92.6 +/- 2.5 degrees) and during defaecation (92 +/- 5.5 degrees vs 98.7 +/- 2.6 degrees) between patients with IBS and healthy volunteers. However, patients with IBS were unable to widen the angle during defaecation, remaining the same at rest (91.6 +/- 3.5 degrees) as during defaecation (92 +/- 5.5 degrees). IBS patients with constipation (n = 2) compared to those with normal frequency defaecation (n = 13) showed no significant differences at rest (95 +/- 6 vs 89.8 +/- 4.1 degrees) and during defaecation (100 +/- vs 88.9 +/- 6.4 degrees). Healthy volunteers widened the angle by more than 5 degrees during defaecation. 2) Perineometry: although not significant, patients with IBS had less perineal descent during the simulated defaecation (1.98 +/- 0.37 cm) than healthy subjects (2.1 +/- 0.3 cm). Nevertheless, during squeeze there was significantly less mobility or perineal descent in patients with IBS than in control subjects (0.21 +/- 0.17 vs 0.95 +/- 0.21 cm; P = 0.01).

CONCLUSIONS

The findings of this study suggest that patients with IBS as a whole, whether constipation predominant or not, showed changes in pelvic-floor mobility.

Follow-up of a human accidental infection by Leishmania (Viannia) braziliensis using conventional immunologic techniques and polymerase chain reaction

The results of a two-year follow-up study of an accidental human infection with Leishmania (Viannia) braziliensis are presented. Western blots, indirect immunofluorescence, and intradermal reaction assays were not able to detect the infection before week 18 postinfection, whereas using the polymerase chain reaction (PCR) on blood samples, parasite DNA was detected at week 8. All test results, except the intradermal reaction followed the cure process and 12 weeks after the last chemotherapy injection (week 36 postinfection), all were negative. However, a year after cure, the PCR became positive again and has remained so for two years. To determine in which blood cell fraction the parasite was evident, enriched lymphocyte and monocyte fractions were assayed by the PCR. These results are discussed in the context of persistent infections.