Mysterious microsporidians: springtime outbreaks of disease in Daphnia communities in shallow pond ecosystems.

Parasites can play key roles in ecosystems, especially when they infect common hosts that play important ecological roles. Daphnia are critical grazers in many lentic freshwater ecosystems and typically reach peak densities in early spring. Daphnia have also become prominent model host organisms for the field of disease ecology, although most well-studied parasites infect them in summer or fall. Here, we report field patterns of virulent microsporidian parasites that consistently infect Daphnia in springtime, in a set of seven shallow ponds in Georgia, USA, sampled every 3-4 weeks for 18 months. We detected two distinct parasite taxa, closely matching sequences of Pseudoberwaldia daphniae and Conglomerata obtusa, both infecting all three resident species of Daphnia: D. ambigua, D. laevis, and D. parvula. To our knowledge, neither parasite has been previously reported in any of these host species or anywhere in North America. Infection prevalence peaked consistently in February-May, but the severity of these outbreaks differed substantially among ponds. Moreover, host species differed markedly in terms of their maximum infection prevalence (5% [D. parvula] to 72% [D. laevis]), mean reduction of fecundity when infected (70.6% [D. ambigua] to 99.8% [D. laevis]), mean spore yield (62,000 [D. parvula] to 377,000 [D. laevis] per host), and likelihood of being infected by each parasite. The timing and severity of the outbreaks suggests that these parasites could be impactful members of these shallow freshwater ecosystems, and that the strength of their effects is likely to hinge on the composition of ponds' zooplankton communities.

Comparative Effectiveness of Switching to Daptomycin Versus Remaining on Vancomycin Among Patients With Methicillin-resistant Staphylococcus aureus (MRSA) Bloodstream Infections.

BACKGROUND: Patients with methicillin-resistant Staphylococcus aureus bloodstream infections (MRSA BSI) usually receive initial treatment with vancomycin but may be switched to daptomycin for definitive therapy, especially if treatment failure is suspected. Our objective was to evaluate the effectiveness of switching from vancomycin to daptomycin compared with remaining on vancomycin among patients with MRSA BSI. METHODS: Patients admitted to 124 Veterans Affairs Hospitals who experienced MRSA BSI and were treated with vancomycin during 2007-2014 were included. The association between switching to daptomycin and 30-day mortality was assessed using Cox regression models. Separate models were created for switching to daptomycin any time during the first hospitalization and for switching within 3 days of receiving vancomycin. RESULTS: In total, 7411 patients received vancomycin for MRSA BSI. Also, 606 (8.2%) patients switched from vancomycin to daptomycin during the first hospitalization, and 108 (1.5%) switched from vancomycin to daptomycin within 3 days of starting vancomycin. In the multivariable analysis, switching to daptomycin within 3 days was significantly associated with lower 30-day mortality (hazards ratio [HR] = 0.48; 95% confidence interval [CI]: .25, .92). However, switching to daptomycin at any time during the first hospitalization was not significantly associated with 30-day mortality (HR: 0.87; 95% CI: .69, 1.09). CONCLUSIONS: Switching to daptomycin within 3 days of initial receipt of vancomycin is associated with lower 30-day mortality among patients with MRSA BSI. This benefit was not seen when the switch occurred later. Future studies should prospectively assess the benefit of early switching from vancomycin to other anti-MRSA antibiotics.

Assessing effects of non-native crayfish on mosquito survival.

Introductions of non-native predators often reduce biodiversity and affect natural predator-prey relationships and may increase the abundance of potential disease vectors (e.g., mosquitoes) indirectly through competition or predation cascades. The Santa Monica Mountains (California, U.S.A.), situated in a global biodiversity hotspot, is an area of conservation concern due to climate change, urbanization, and the introduction of non-native species. We examined the effect of non-native crayfish (Procambarus clarkii) on an existing native predator, dragonfly nymphs (Aeshna sp.), and their mosquito larvae (Anopheles sp.) prey. We used laboratory experiments to compare the predation efficiency of both predators, separately and together, and field data on counts of dragonfly nymphs and mosquito larvae sampled from 13 local streams. We predicted a lower predation efficiency of crayfish compared with native dragonfly nymphs and a reduced predation efficiency of dragonfly nymphs in the presence of crayfish. Dragonfly nymphs were an order of magnitude more efficient predators than crayfish, and dragonfly nymph predation efficiency was reduced in the presence of crayfish. Field count data showed that populations of dragonfly nymphs and mosquito larvae were strongly correlated with crayfish presence in streams, such that sites with crayfish tended to have fewer dragonfly nymphs and more mosquito larvae. Under natural conditions, it is likely that crayfish reduce the abundance of dragonfly nymphs and their predation efficiency and thereby, directly and indirectly, lead to higher mosquito populations and a loss of ecosystem services related to disease vector control.

Abiotic and biotic factors jointly influence the contact and environmental transmission of a generalist pathogen.

The joint influence of abiotic and biotic factors is important for understanding the transmission of generalist pathogens. Abiotic factors such as temperature can directly influence pathogen persistence in the environment and will also affect biotic factors, such as host community composition and abundance. At intermediate spatial scales, the effects of temperature, community composition, and host abundance are expected to contribute to generalist pathogen transmission. We use a simple transmission model to explain and predict how host community composition, host abundance, and environmental pathogen persistence times can independently and jointly influence transmission. Our transmission model clarifies how abiotic and biotic factors can synergistically support the transmission of a pathogen. The empirical data show that high community competence, high abundance, and low temperatures correlate with high levels of transmission of ranavirus in larval amphibian communities. Discrete wetlands inhabited by larval amphibians in the presence of ranavirus provide a compelling case study comprising distinct host communities at a spatial scale anticipated to demonstrate abiotic and biotic influence on transmission. We use these host communities to observe phenomena demonstrated in our theoretical model. These findings emphasize the importance of considering both abiotic and biotic factors, and concomitant direct and indirect mechanisms, in the study of pathogen transmission and should extend to other generalist pathogens with the capacity for environmental transmission.

Healthcare worker attitudes on routine non-urological preoperative urine cultures: a qualitative assessment.

OBJECTIVE: Many preoperative urine cultures are of low value and may even lead to patient harms. This study sought to understand practices around ordering preoperative urine cultures and prescribing antibiotic treatment. DESIGN: Open-ended, semi-structured qualitative interviews. SETTING: 5 Veterans Affairs hospitals. PARTICIPANTS: Interviews with 14 surgeons (9 surgeons, 5 surgical leaders), 7 infectious disease physicians, 8 surgical advanced practice providers (APPs), 1 surgical nurse manager, 3 infectious disease pharmacists, 1 hospitalist, and 1 lab manager. METHODS: We interviewed participants using a qualitative semi-structured interview guide. Collected data was coded inductively and with the Dual Process Model (DPM) using MAXQDA software. Data in the "Testing Decision-Making" code was further reviewed using the concept of perceived risk as a sensitizing concept. RESULTS: We identified themes relating to surgeons' concerns about de-implementing preoperative urine cultures to detect asymptomatic bacteriuria (ASB) in patients undergoing non-urological procedures: (1) anxiety and uncertainty surrounding missing infection signs spanned surgical specialties, (2) there were perceived risks of negative consequences associated with omitting urine cultures and treatment prior to specific procedure sites and types, and additionally, (3) participants suggested potential routes for adjusting these perceived risks to facilitate de-implementation acceptance. Notably, participants suggested that leadership support and peer engagement could help improve surgeon buy-in. CONCLUSIONS: Concerns about perceived risks sometimes outweigh the evidence against routine preoperative urine cultures to detect ASB. Evidence from trusted peers may improve openness to de-implementing preoperative urine cultures.

Therapy for alopecia areata in mice using parathyroid hormone agonists and antagonists, linked to a collagen-binding domain.

Alopecia areata is a common form of hair loss in which autoimmune-mediated destruction of hair follicles causes patchy hair loss, for which there is no adequate therapy. Parathyroid hormone (PTH) induces the hair cycle and promotes hair growth. PTH-CBD is a fusion protein of PTH and a bacterial collagen-binding domain (CBD), leading to targeted delivery to and retention in the skin collagen. We tested the effects of a single dose of PTH-CBD (low or high dose) on an animal model for alopecia areata, the C3H/HeJ engrafted mouse. In all the treated animals, there was a rapid (1-4 days) increase in hair growth, with sustained effects observed over a 2-month period (7/10 total treated mice<40% hair loss based on gray scale analysis, vs. 2/5 in vehicle control animals). Histological examination revealed massive stimulation of anagen VI hair follicles in treated animals despite an ongoing immune response. PTH-CBD thus shows promise as a therapy for alopecia areata, likely in conjunction with a mild immune suppressant, such as hydrocortisone cream.

C5L2 is critical for the biological activities of the anaphylatoxins C5a and C3a.

Complement-derived anaphylatoxins regulate immune and inflammatory responses through G-protein-coupled receptor (GPCR)-mediated signalling. C5L2 (also known as GPR77) is a relatively new GPCR thought to be a non-signalling receptor binding to C5a, on the basis of sequence information and experimental evidence. Here we show, using gene targeting, that C5L2 is required to facilitate C5a signalling in neutrophils, macrophages and fibroblasts in vitro. Deficiency of C5L2 results in reduced inflammatory cell infiltration, suggesting that C5L2 is critical for optimal C5a-mediated cell infiltration in certain in vivo settings. C5L2 is also involved in optimizing C3a-induced signals. Furthermore, like mice incapable of C3a/complement 3a receptor (C3aR) signalling, C5L2-deficient mice are hypersensitive to lipopolysaccharide (LPS)-induced septic shock, show reduced ovalbumin (OVA)-induced airway hyper-responsiveness and inflammation, and are mildly delayed in haematopoietic cell regeneration after gamma-irradiation. Our data indicate that C5L2 can function as a positive modulator for both C5a- and C3a-anaphylatoxin-induced responses.

The use of UV-C radiation for terminal disinfection of pathogenic Gram-negative rods: a pilot study.

In this controlled study, we found that exposure to ultraviolet-C (UV-C) radiation was able to arrest the growth of selected pathogenic enteric and nonfermenting Gram-negative rods. Further studies are needed to confirm the clinical efficacy and determine optimal implementation strategies for utilizing UV-C terminal disinfection.

Implementation of a surgical site infection prevention bundle: Patient adherence and experience.

We evaluated barriers and facilitators to patient adherence with a bundled intervention including chlorhexidine gluconate (CHG) bathing and decolonizing Staphylococcus aureus nasal carriers in a real-world setting. Survey data identified 85.5% adherence with home use of CHG as directed and 52.9% adherence with home use of mupirocin as directed.

Children's exposure to spatial language promotes their spatial thinking.

Does spatial language contribute to the growth of preschool children's spatial skills? Four-year-old children (N = 50) were randomly assigned to a play-only (n = 24) or a spatial-language and play condition (n = 26). Their mental rotation and spatial vocabulary were assessed at baseline and several days after 5 play sessions. Children in the spatial-language condition scored higher at posttest on a mental rotation task than those in the play-only condition. The amount and diversity of experimenter spatial language during the play sessions accounted for a significant amount of the variance on children's posttest mental rotation. Significant gains in mental rotation were replicated in a second study (N = 34) with a broader range of play activities and with children enrolled in Head Start. These results show that the facilitative effects of spatial language on spatial cognition are not restricted to the context in which the spatial language is provided. In particular, 4-year-old children's experience with spatial language during play can transfer to promote their mental rotation. (PsycInfo Database Record (c) 2020 APA, all rights reserved).

Children's Block-Building Skills and Mother-Child Block-Building Interactions Across Four U.S. Ethnic Groups.

Play offers an unparalleled opportunity for young children to gain cognitive skills in informal settings. Block play in particular-including interactions with parents around block constructions-teaches children about intrinsic spatial features of objects (size, shape) and extrinsic spatial relations. In turn, early spatial cognition paves the way for later competencies in math and science. We assessed 4- and 5-year-old children's spatial skill on a set of block-building constructions and examined mother-child block building interactions in 167 U.S. dyads from African American, Dominican, Mexican, and Chinese backgrounds. At both ages, children were instructed to copy several 3D block constructions, followed by a "break" during which mothers and children were left alone with the blocks. A form that contained pictures of test items was left on the table. Video-recordings of mother-child interactions during the break were coded for two types of building behaviors - test-specific construction (building structures on the test form) or free-form construction (building structures not on the test form). Chinese children outperformed Mexican, African American, and Dominican children on the block-building assessment. Further, Chinese and Mexican mother-child dyads spent more time building test-specific constructions than did African American and Dominican dyads. At an individual level, mothers' time spent building test-specific constructions at the 4-year (but not 5-year) assessment, but not mothers' initiation of block building interactions or verbal instructions, related to children's performance, when controlling for ethnicity. Ethnic differences in children's block-building performance and experiences emerge prior to formal schooling and provide a valuable window into sources of individual differences in early spatial cognition.

Ultrastretchable Analog/Digital Signal Transmission Line with Carbon Nanotube Sheets.

Stretchable conductors can be used in various applications depending on their own characteristics. Here, we demonstrate simple and robust elastomeric conductors that are optimized for stretchable electrical signal transmission line. They can withstand strains up to 600% without any substantial change in their resistance (≤10% as is and ≤1% with passivation), and exhibit suppressed charge fluctuations in the medium. The inherent elasticity of a polymeric rubber and the high conductivity of flexible, highly oriented carbon nanotube sheets were combined synergistically, without losing both properties. The nanoscopic strong adhesion between aligned carbon nanotube arrays and strained elastomeric polymers induces conductive wavy folds with microscopic bending of radii on the scale of a few micrometers. Such features enable practical applications such as in elastomeric length-changeable electrical digital and analog signal transmission lines at above MHz frequencies. In addition to reporting basic direct current, alternating current, and noise characterizations of the elastomeric conductors, various examples as a stretchable signal transmission line up to 600% strains are presented by confirming the capability of transmitting audio and video signals, as well as low-frequency medical signals without information distortion.

Investigations of a common genetic variant in betaine-homocysteine methyltransferase (BHMT) in coronary artery disease.

Hyperhomocysteinemia, a risk factor for cardiovascular disease, can be caused by genetic mutations in enzymes of homocysteine metabolism. Homocysteine remethylation to methionine is catalyzed by folate-dependent methionine synthase, or by betaine-homocysteine methyltransferase (BHMT), which utilizes betaine as the methyl donor. Since genetic variants in folate-dependent remethylation have been reported to increase risk for cardiovascular disease and other common disorders, we screened BHMT for sequence changes that might alter risk for coronary artery disease (CAD). A variant in exon 6-R239Q-was identified. The frequency of this change was examined in 504 individuals who had undergone coronary angiography and were stratified into controls (those with no or mild disease) and cases (those with significant [>50% reduction in luminal diameter stenosis] 1-, 2-, 3-vessel disease). Although this variant did not affect plasma homocysteine, the QQ genotype was present in higher frequency in those with no or mild disease, compared with those with significant disease (11 vs. 6%), suggesting that it may decrease risk of CAD; a statistically-significant decrease was seen in the older subjects (13 vs. 7%). Multivariate analysis for the entire group revealed an odds ratio of 0.48 (95% CI: 0.21-1.06) for the QQ genotype; this association was similar in the younger (OR=0.36; 95% CI: 0.09-1.41) and older subjects (OR=0.42; 95% CI: 0.15-1.18). Our study suggests that the Q allele of the R239Q mutation may decrease the risk of CAD and that this variant warrants additional investigation of its relationship with the development of CAD as well as other homocysteine-dependent disorders.

Diffusion-weighted magnetic resonance imaging in Shaken Baby Syndrome.

PURPOSE: To evaluate the role of diffusion-weighted magnetic resonance imaging (DWIMRI) in the diagnosis and management of children with suspected or confirmed Shaken Baby Syndrome (SBS). METHODS: This was a retrospective interventional case series of all infants and children younger than 2 years of age admitted to a children's hospital. We retrospectively reviewed medical records and neuroimaging findings of all children younger than 2 years of age with confirmed or suspected SBS admitted to a children's hospital. Inclusion criteria were documented ocular examination by an ophthalmologist and a brain MRI with DWI. Twenty-six infants and children were included. Other children were excluded. Children with proven SBS were diagnosed with "confirmed SBS," while children in whom the diagnosis of SBS remained uncertain were diagnosed with "suspected SBS." RESULTS: Twenty-six infants and children with mean age of 7.1 months (range, 6 weeks-24 months) were included, 18 with confirmed SBS. All 26 patients had a subdural hematoma, 10 had associated occult bone fractures, and 18 had retinal hemorrhages. Seven of the eight cases without retinal hemorrhages had isolated subdural hematoma without parenchymal brain lesions on both conventional MRI and DWIMRI. SBS was confirmed in only one case with a normal fundus. Among the 18 patients with retinal hemorrhages, SBS was confirmed in all but one case. All 18 patients with confirmed SBS had an abnormal DWIMRI. In 13 patients, DWI showed lesions that were larger than on conventional MRI. In patients with brain parenchymal lesions, the DWIMRI characteristics suggested cerebral ischemia, which appears to play a major role in SBS. CONCLUSIONS: In all patients with confirmed SBS, DWIMRI was abnormal and suggested diffuse or posterior cerebral ischemia, in addition to subdural hematomas in the pathogenesis of this disorder.

Capture and stimulated release of circulating tumor cells on polymer-grafted silicon nanostructures.

A platform for capture and release of circulating tumor cells is demonstrated by utilizing polymer grafted silicon nanowires. In this platform, integration of ligand-receptor recognition, nanostructure amplification, and thermal responsive polymers enables a highly efficient and selective capture of cancer cells. Subsequently, these captured cells are released upon a physical stimulation with outstanding cell viability.

SLC7A9 mutations in all three cystinuria subtypes.

BACKGROUND: Cystinuria is an inherited disorder of cystine and dibasic amino acid transport in kidney. Subtypes are defined by the urinary cystine excretion patterns of the obligate heterozygous parents: Type I/N (fully recessive or silent); Type II/N (high excretor); Type III/N (moderate excretor). The first gene implicated in cystinuria (SLC3A1) is associated with the Type I urinary phenotype. A second cystinuria gene (SLC7A9) was recently isolated, and mutations of this gene were associated with dominant (non-Type I) cystinuria alleles. Here we report genotype-phenotype studies of SLC7A9 mutations in a cohort of well-characterized cystinuria probands and their family members. METHODS: Individual exons of the SLC7A9 gene were screened by single strand conformation polymorphism (SSCP) analysis and sequencing of abnormally migrating fragments. RESULTS: Seven mutations were identified. A single bp insertion (799insA) was present in four patients: on Type III alleles in two patients and on Type II alleles in two patients. These results suggest that Type II and Type III may be caused by the same mutation and, therefore, other factors must influence urinary cystine excretion. A 4bp deletion in intron 12 (IVS12+4delAGTA) and a missense mutation (1245G-->A, A354T) were identified on Type III alleles. A nonsense codon (1491G-->T, E436X) and a possible splicing mutation (IVS9-17G-->A) were seen in a Type I/III patient, but the mutations could not be assigned to particular alleles. Of additional interest were two missense mutations (316T-->C, I44T and 967C-->T, P261L) linked to Type I alleles. CONCLUSION: Our results provide evidence that some SLC7A9 mutations may be associated with fully recessive (Type I) forms of cystinuria. We also demonstrate SLC7A9 mutations in dominant Types II and III cystinuria. The finding of SLC7A9 mutations in all three subtypes underscores the complex interactions between specific cystinuria genes and other factors influencing cystine excretion. A simpler phenotypic classification scheme (recessive and dominant) for cystinuria is warranted.

Mapping of determinants required for the function of the HIV-1 env nuclear retention sequence.

Control of HIV-1 RNA processing and transport are critical to the successful replication of the virus. In previous work, we identified a region within the HIV-1 env that is involved in mediating nuclear retention of unspliced viral RNA. To define this sequence further and identify elements required for function, deletion mutagenesis was carried out. Progressive 5' and 3' deletions map the nuclear retention sequence (NRS) within the intron between nts 8281 and 8381. While deletion of sequences comprising the 3'ss had no effect, removal of the 5'ss resulted in cytoplasmic accumulation of unspliced RNA. Sequence analysis determined that the region corresponding to the NRS is highly conserved among HIV-1 strains. To evaluate whether this NRS interacts with cellular factors, RNA electrophoretic mobility shift assays (REMSA) were performed. We show that the NRS specifically interacts with cellular factors present in HeLa nuclear extracts, and, by UV crosslinking, correlates with the binding of a 49-kDa protein. Immunoprecipitation of the UV crosslinked products determined that this 49-kDa protein corresponds to hnRNP C.

Overcoming the immune response to permit ex vivo gene therapy for spine fusion with human type 5 adenoviral delivery of the LIM mineralization protein-1 cDNA.

STUDY DESIGN: An animal study in immune competent rabbits and athymic rats was conducted. OBJECTIVES: To develop an animal model for simulation of previous human Type 5 adenovirus (Ad5) exposure, to determine the impact of adenoviral pre-exposure on spine fusion induced with ex vivo Ad5-LMP-1, and to test strategies for overcoming any potential immune response. SUMMARY OF BACKGROUND DATA: Cells transduced with adenovirus containing the osteoinductive LMP-1 cDNA (Ad5-LMP-1) can induce spine fusion in rabbits. Because up to 80% of the human population has been exposed to adenovirus, immune responses to the vector may limit this strategy in humans. Few studies have modeled previous adenoviral exposure and tested strategies to circumvent it. METHODS: Adult New Zealand white rabbits were injected with 10 or 10 viral particles of Ad5-LacZ. At 4 or 16 weeks after Ad5 injection, autologous buffy coats were prepared from peripheral blood, and 4 million cells per side were infected ex vivo for 10 minutes with Ad5-LMP-1 (multiplicity of infection = 4). Cells were implanted on a collagen matrix instead of an autograft for posterolateral lumbar arthrodesis. Unimmunized rabbits served as control subjects. Additional immunized rabbits underwent arthrodesis at 4 weeks with increased cell number (10 million) and viral dose (multiplicity of infection = 10), or with both parameters increased. The rabbits were killed at 4 weeks, and the spines were assessed by palpation and radiograph. A parallel study was performed in athymic rats using immunized rabbits for the donor cells. RESULTS: All the unimmunized rabbits had solid spine fusions. None of the rabbits arthrodesed 4 weeks after Ad5 pre-exposure achieved fusion. At 4 weeks after Ad5 exposure, increasing the multiplicity of infection to 10 did not overcome the immune response (0/3 fused), but increasing the cell number to 10 million (2/3 fused) or increasing both cell number and multiplicity of infection (3/3 fused) did overcome the immune effects. Delaying arthrodesis until 16 weeks after Ad5 pre-exposure also overcame the immune response (3/3 fused). Similar results were seen in the athymic rat ectopic implant model, suggesting that the immune effect was mediated by humoral antibodies rather than a T-cell response. CONCLUSIONS: Two model systems were developed that simulate previous exposure to human Ad5 and could separate the cellular and humoral components of the response. There was a dose-dependent inhibition of ex vivo Ad5-LMP-1 gene transfer to cells from animals previously exposed to human Ad5. Data suggested that the inhibition of Ad5 infection was caused by humoral antibodies rather than a T-cell-based response. Minor modifications in the gene transfer protocol, such as doubling the viral dose or number of cells infected, or increasing the infection time, could overcome the immune response for an ex vivo approach.