Neuroprotective effects of erythropoietin on 6-hydroxydopamine-treated ventral mesencephalic dopamine-rich cultures.

Parkinson's disease (PD) is a neurodegenerative disorder with motor symptoms caused by the loss of dopaminergic (DA) cells and consequently dopamine release in the nigrostriatal system. In vivo and in vitro 6-hydroxydopamine (6-OHDA) PD models are widely used to study the effect of striatal dopamine depletion as well as novel neuroprotective or restorative therapeutic strategies for PD. In the present study, we investigated in vitro the toxicity of 6-OHDA on DA neurons derived from E14 rat ventral mesencephalon (VM) and the neuroprotective efficiency of erythropoietin (Epo) on VM-derived cell cultures against 6-OHDA toxicity. Using E14 VM-derived DA-rich primary cultures, we could demonstrate that 6-OHDA toxicity works in a time-and concentration-dependent way, and leads to cell death not only in DA cells but also in non-DA cells in direct relation to concentration and incubation times. In addition, we found that 6-OHDA toxicity induces caspase-3 activation and an increment of intracellular reactive oxygen species (ROS) in VM-derived cultures. When 6-OHDA-treated VMs were cultured in the presence of the anti-apoptotic protein erythropoietin (Epo), the total neuronal population, including the DA neurons, was protected. However, untreated VM cultures exposed to Epo showed an increase in the total neuronal population, but not an additional increase in DA neuron cell number. These findings suggest that 6-OHDA toxicity is time and concentration-dependent and does not exclusively affect DA neurons. In high concentration and long incubation times, 6-OHDA influences the survival of other neuronal and non-neuronal cell populations derived from the VM cultures. 6-OHDA toxicity induces caspase-3 activation, indicating cell death via the apoptotic pathway which could be restricted or even prevented by pre-exposure to Epo, known to interact via the apoptotic pathway. Our results support and expand on previous findings showing that Epo is an interesting candidate molecule to mediate neuroprotective effects on DA neurons in PD. Furthermore, it could be used in promoting the survival of DA neurons after transplantation in clinical trials.

Validating Species Distribution Models With Standardized Surveys for Ixodid Ticks in Mainland Florida.

Tick-borne pathogens are of growing concern. The U.S. Centers for Disease Control and Prevention (CDC) developed guidelines standardizing surveys of tick vectors to better monitor the changes in their occurrences. Unbiased surveillance data, from standardized surveys, are presumed critical to generate valid species distribution models (SDMs). We tested previously generated SDMs from standardized protocols for three medically important ticks [Amblyomma americanum (Linnaeus, Ixodida, Ixodidae), Ixodes scapularis (Say, Ixodida, Ixodidae), and Dermacentor variabilis (Say, Ixodida, Ixodidae)]. These previous models ruled out a quarter to half of the state as having these species, with consensus occurrence in about a quarter of the state. New surveys performed throughout 2019 on 250 transects at 43 sites indicated the rule-out functions were 100% accurate for I. scapularis and D. variabilis and 91.9% for A. americanum. As SDM concordance increased, the proportion of transects yielding ticks increased. Independent surveys of SDMs provide external validation-an aspect missing from many SDM studies.

A Survey of Tick Surveillance and Control Practices in the United States.

Tickborne diseases are an increasing public health threat in the United States. Prevention and diagnosis of tickborne diseases are improved by access to current and accurate information on where medically important ticks and their associated human and veterinary pathogens are present, their local abundance or prevalence, and when ticks are actively seeking hosts. The true extent of tick and tickborne pathogen expansion is poorly defined, in part because of a lack of nationally standardized tick surveillance. We surveyed 140 vector-borne disease professionals working in state, county, and local public health and vector control agencies to assess their 1) tick surveillance program objectives, 2) pathogen testing methods, 3) tick control practices, 4) data communication strategies, and 5) barriers to program development and operation. Fewer than half of respondents reported that their jurisdiction was engaged in routine, active tick surveillance, but nearly two-thirds reported engaging in passive tick surveillance. Detection of tick presence was the most commonly stated current surveillance objective (76.2%). Most of the programs currently supporting tick pathogen testing were in the Northeast (70.8%), Upper and Central Midwest (64.3%), and the West (71.4%) regions. The most common pathogens screened for were Rickettsia spp. (Rickettsiales: Rickettsiaceae) and bacterial and viral agents transmitted by Ixodes (Acari: Ixodidae) ticks. Only 12% of respondents indicated their jurisdiction directly conducts or otherwise financially supports tick control. Responses indicated that their ability to expand the capacity of tick surveillance and control programs was impeded by inconsistent funding, limited infrastructure, guidance on best practices, and institutional capacity to perform these functions.

Is it best on the nest? Effects of avian life-history on haemosporidian parasitism.

Infectious diseases vary in prevalence and pathology among host species. Species may differ in prevalence of infection due to varying exposure and susceptibility to disease agents throughout their lifetime, which may be attributable to underlying differences in their phenology, physiology and behavior. A recently growing body of literature has focused on the utility of host life-history traits to provide mechanistic explanations for interspecific variation in host-parasite associations. In this study, we utilized diverse avian and haemosporidian assemblages in an African savanna to evaluate the link between haemosporidia prevalence (Plasmodium, Haemoproteus, Leucocytozoon) and avian life-history traits such as body size, mating system, nest care and nest structure. We found that variation of haemosporidia prevalence was consistent with life-history traits that pertain to the reproduction of avian host. Nest care was the single most important predictor of infection status. In birds with shared and female-only nest care, the expected rates of parasitism were between 8- and 12-fold higher than in avian brood parasites that provide no nest care. This finding supports the hypothesis that parental care is an evolutionarily costly life-history trait that increases species' risk of infection with vector-borne diseases. The influence of other host traits (nest structure, body size) was less consistent suggesting that differences in the vectors' ecology and host-seeking behavior produce variable patterns of parasitism among haemosporidia genera. Nest structure influenced infection with Haemoproteus and Leucocytozoon only. Leucocytozoon infections were associated with ground-nesting birds, while Haemoproteus infections were associated with birds that build open nest structures. Body size was an important predictor of Leucocytozoon infections, particularly large-bodied birds like guineafowl and doves, which exhibited high prevalences.

Modeling the Distribution of Medically Important Tick Species in Florida.

The lone star (Amblyomma americanum), black-legged (Ixodes scapularis) and American dog ticks (Dermacentor variabilis) are species of great public health importance as they are competent vectors of several notable pathogens. While the regional distributions of these species are well characterized, more localized distribution estimates are sparse. We used records of field collected ticks and an ensemble modeling approach to predict habitat suitability for each of these species in Florida. Environmental variables capturing climatic extremes were common contributors to habitat suitability. Most frequently, annual precipitation (Bio12), mean temperature of the driest quarter (Bio9), minimum temperature of the coldest month (Bio6), and mean Normalized Difference Vegetation Index (NDVI) were included in the final models for each species. Agreement between the modeling algorithms used in this study was high and indicated the distribution of suitable habitat for all three species was reduced at lower latitudes. These findings are important for raising awareness of the potential for tick-borne pathogens in Florida.

Standardized Ixodid Tick Survey in Mainland Florida.

A statewide survey of questing ixodid ticks in mainland Florida was developed consistent with U.S. CDC standards to maximize the amount of epidemiologic and environmental data gathered. Survey sites were stratified by climatic zones and proportional to recognized land cover categories. A total of 560 transects on 41 sites within the state were sampled repeatedly by flagging between 2015 and 2018. Four tick species were collected; Amblyomma americanum, Amblyomma maculatum, Ixodes scapularis and Dermacentor variabilis. All species were more commonly found in northern and central regions of the state than in southern and western regions. Adult I. scapularis were active from autumn through spring and complementary to adult A. americanum and D. variabilis. Standardized survey methods help reduce sampling biases and better characterize risk from the species surveyed. However, differences in the attractiveness of collection methods for different tick species makes cross-species comparisons a continuing challenge.

A Survey of Tick-Borne Bacterial Pathogens in Florida.

Within the past three decades, new bacterial etiological agents of tick-borne disease have been discovered in the southeastern U.S., and the number of reported tick-borne pathogen infections has increased. In Florida, few systematic studies have been conducted to determine the presence of tick-borne bacterial pathogens. This investigation examined the distribution and presence of tick-borne bacterial pathogens in Florida. Ticks were collected by flagging at 41 field sites, spanning the climatic regions of mainland Florida. DNA was extracted individually from 1608 ticks and screened for Anaplasma, Borrelia, Ehrlichia and Rickettsia using conventional PCR and primers that amplified multiple species for each genus. PCR positive samples were Sanger sequenced. Four species of ticks were collected: Amblyomma americanum, Amblyomma maculatum, Dermacentor variabilis, and Ixodes scapularis. Within these ticks, six bacterial species were identified: Borrelia burgdorferi, Borrelia lonestari, Ehrlichia ewingii, Rickettsia amblyommatis, Rickettsia andeanae, Rickettsia parkeri, and Rickettsia endosymbionts. Pathogenic Borrelia, Ehrlichia, and Rickettsia species were all detected in the North and North-Central Florida counties; however, we found only moderate concordance between the distribution of ticks infected with pathogenic bacteria and human cases of tick-borne diseases in Florida. Given the diversity and numerous bacterial species detected in ticks in Florida, further investigations should be conducted to identify regional hotspots of tick-borne pathogens.

Fine-scale distribution modeling of avian malaria vectors in north-central Kansas.

Infectious diseases increasingly play a role in the decline of wildlife populations. Vector-borne diseases, in particular, have been implicated in mass mortality events and localized population declines are threatening some species with extinction. Transmission patterns for vector-borne diseases are influenced by the spatial distribution of vectors and are therefore not uniform across the landscape. Avian malaria is a globally distributed vector-borne disease that has been shown to affect endemic bird populations of North America. We evaluated shared habitat use between avian malaria vectors, mosquitoes in the genus Culex and a native grassland bird, the Greater Prairie-Chicken (Tympanuchus cupido), by (1) modeling the distribution of Culex spp. occurrence across the Smoky Hills of north-central Kansas using detection data and habitat variables, (2) assessing the occurrence of these vectors at nests of female Greater Prairie-Chickens, and (3) evaluating if shared habitat use between vectors and hosts is correlated with malarial infection status of the Greater Prairie-Chicken. Our results indicate that Culex occurrence increased at nest locations compared to other available but unoccupied grassland habitats; however the shared habitat use between vectors and hosts did not result in an increased prevalence of malarial parasites in Greater Prairie-Chickens that occupied habitats with high vector occurrence. We developed a predictive map to illustrate the associations between Culex occurrence and infection status with malarial parasites in an obligate grassland bird that may be used to guide management decisions to limit the spread of vector-borne diseases.

Influence of land use and climate on Salmonella carrier status in the small Indian mongoose (Herpestes auropunctatus) in Grenada, West Indies.

Invasive mammals can be important reservoirs for human pathogens. A recent study showed that 12% of mongooses carried Salmonella spp. in their large intestines. We investigated whether anthropogenic, environmental and climatic variables predicted Salmonella status in mongooses (Herpestes auropunctatus) in Grenada. Using multivariate logistic regression and contingency table analysis, we found that increased human density, decreased distance from roads, and low monthly precipitation were associated with increased probability of Salmonella carriage. Areas with higher human density likely support a higher abundance of mongooses because of greater food availability. These areas also are a likely source for infection to mongooses due to high densities of livestock and rodents shedding Salmonella. The higher probability of Salmonella carriage in mongooses during drier months and closer to roadsides is likely due to water drainage patterns and limited water availability. Although the overall prevalence of Salmonella in mongooses was moderate, the strong patterns of ecologic correlates, combined with the high density of mongooses throughout Grenada suggest that the small Indian mongoose could be a useful sentinel for Salmonella surveillance. Its affinity for human-associated habitats suggests that the small Indian mongoose is also a risk factor in the maintenance and possible spread of Salmonella species to humans and livestock in Grenada.

Patterns of spatio-temporal distribution, abundance, and diversity in a mosquito community from the eastern Smoky Hills of Kansas.

Nearly 30% of emerging infectious disease events are caused by vector-borne pathogens with wildlife origins. Their transmission involves a complex interplay among pathogens, arthropod vectors, the environment and host species, and they pose a risk for public health, livestock and wildlife species. Examining habitat associations of vector species known to transmit infectious diseases, and quantifying spatio-temporal dynamics of mosquito vector communities is one aspect of the holistic One Health approach that is necessary to develop effective control measures. A survey was conducted from May to August, 2010 of the abundance and diversity of mosquito species occurring in the mixed-grass prairie habitat of the Smoky Hills of Kansas. This region is an important breeding ground for North America's grassland nesting birds and, as such, it could represent an important habitat for the enzootic amplification cycle of avian malaria and infectious encephalitides, as well as spill-over events to humans and livestock. A total of 11 species, belonging to the three genera Aedes, Anopheles, and Culex, was collected during this study. Aedes nigromaculis, Ae. sollicitans, Ae. taeniorhynchus, Culex salinarius, and Cx. tarsalis accounted for 98% of the collected species. Multiple linear regression models suggested that mosquito abundances in the grasslands of the central Great Plains were explained by meteorological and environmental variables. Temporal dynamics in mosquito abundances were well supported by models that included maximum and minimum temperature indices (adjusted R(2) = 0.73). Spatial dynamics of mosquito abundances were best explained by a model containing the following environmental variables (adjusted R(2) =0.37): ground curvature, topographic wetness index, distance to woodland, and distance to road. The mosquito species we detected are known vectors for infectious encephalitides, including West Nile virus. Understanding the microhabitat characteristics of these mosquito species in a grassland ecosystem will aid in the control and management of these disease vectors.

The Lewis GFP transgenic rat strain is a useful cell donor for neural transplantation.

Stem cell transplantation is a promising therapeutic approach in neurodegenerative diseases. Studying graft survival and development has important implications for the further development of experimental and clinical transplantation protocols. Cellular elements in neural transplants are sometimes difficult to identify. The existing labeling methods cannot reliably provide stably labeled cells that can be detected in long-term experiments. Transgenic (tg) Lewis rats ubiquitously expressing green fluorescent protein (GFP) provide an ideal donor source. The aim of this project was to investigate the potential of GFP-tg Lewis rats to serve as donor tissue for neural stem cell transplantation. Ventral mesencephalon (VM) GFP-tg E14.5-derived cells were compared to wild-type (wt) in vitro and in vivo. Firstly, cells from GFP and non-GFP VM tissue were compared with regard to their proliferation and response towards 6-OHDA-toxicity in culture. Secondly, 6-OHDA-lesioned hemiparkinsonian Sprague-Dawley/Crl:CD(SD) rats received intrastriatal grafts derived from VM of E14.5 GFP-tg rats. Due to the fact that donor and recipient belong to two different rat strains, we focused on graft survival in correlation with immunosuppression and graft GFP and tyrosine hydroxylase (TH) expression. In summary, in vitro tg cells exhibited 98% GFP expression and did not differ from wt cells in any of the measured parameters. In vivo, all experimental groups showed a significant compensation in rotation behavior after transplantation. Furthermore, there was no difference on rotation behavior or graft morphology and survival pattern as well as GFP expression between immunosuppressed and nonimmunosuppressed animals. The GFP-positive population of the graft was composed of 13.3% GFAP-positive, 56.1% NeuN-positive, and 1.9% TH-positive cells. Analysis of graft subpopulations manifested that 70.6% of GFAP-positive, 86.9% of NeuN-positive, and 80.1% of TH-positive cells coexpressed GFP. In conclusion, our data show that the Lewis GFP-tg rats serve as an excellent cell source for studying primary neural precursor cells in the transplantation paradigm.

Facile synthesis and supramolecular chemistry of hydrogen bond/halogen bond-driven multi-tasking tectons.

Hydrogen bonds and halogen bonds can be used as synthetic vectors without structural interference as long as the primary molecular recognition events are designed around a careful combination of geometric and electrostatic complementarity. In addition, a one-step procedure for the synthesis of tectons equipped with powerful hydrogen- and halogen-bond donors is presented.

Ectopic dopaminergic progenitor cells from En1(+/Otx2lacZ) transgenic mice survive and functionally reinnervate the striatum following transplantation in a rat model of Parkinson's disease.

Cell-based therapies for Parkinson's disease (PD) using neural stem cells to replace the lost dopamine neurons is currently an intense area of research. In this study we have evaluated the restorative potential of ectopic dopaminergic (DA) neurons derived from the rostral hindbrain (RH) of En1(+/Otx2lacZ) transgenic mice. The genetic modification of the DA progenitor domain in the En1(+/Otx2lacZ) mice is a gain of function, resulting in the enlargement of the area containing DA neurons, as well as an increase in their absolute number in the midbrain/hindbrain region. Amphetamine-induced rotation performed after cell transplantation into the unilaterally 6-hydroxydopamine-lesioned rat striatum revealed that animals with transgenic RH-derived DA grafts exhibited functional recovery similar to transgenic and wild-type ventral mesencephalon (VM)-derived DA grafts. Morphological analyses revealed equivalent numbers of surviving DA neurons from both homotopic VM- and ectopic RH-derived grafts from transgenic donors with low numbers of surviving serotonergic (5-HT) neurons. Conversely, grafts derived from wild-type donors contained predominantly surviving DA neurons or 5-HT neurons when they were prepared from the VM or RH, respectively. The study demonstrates the pattern of survival and functional potential of ectopic DA neurons derived from the RH of En1(+/Otx2lacZ) transgenic mice and that cell transplantation is an important neurobiological tool to characterize newly generated DA neural stem cells in vivo.