Residential segregation and Black-White differences in physical and mental health: Evidence of a health paradox?

Ample research finds that residential segregation is detrimental to Black Americans' physical health and exacerbates Black-White physical health disparities. However, less is known about how residential segregation may influence Black Americans' mental health and Black-White differences in mental health. Drawing on U.S. census data and a state representative study of Indiana residents (N = 2,685), I examine associations between residential segregation and multiple dimensions of physical and mental health. Consistent with past research, I find that residential segregation has an adverse association with physical health among Black respondents. In contrast, I find residential segregation to have a salubrious association with Black respondents' mental health, producing a Black mental health advantage at higher levels of segregation. I conclude by discussing the implications of these findings for research on residential segregation and health and the Black-White mental health paradox.

Social Networks, the COVID-19 Pandemic, and Mental Health: Resiliency Through Social Bonding and Cohesion

Objectives. To assess how personal social network characteristics moderated mental health declines during the COVID-19 pandemic in emerging adults compared with other age groups. Methods. The Person to Person Health Interview Study, a representative, probability-based cohort study (n = 2485) collected data through face-to-face (baseline) and phone (follow-up) interviews before and during the pandemic. We used survey-weighted growth curve models to examine network effects on computer-adaptive testing measures of depression and anxiety severity. Results. Respondents reported significantly increased depression and anxiety in 2021, which returned almost to baseline levels for most age groups by 2022 (P < .001). Stronger ties to others and more interconnected ties were significantly associated with lower depression (B = -0.112 [P < .05]; B = -0.086 [P < .001]) and anxiety (B = -0.101 [P < .05]; B = -0.063 [P < .01]) severity across the pandemic. Interaction models revealed disproportionate protective effects of network characteristics on depression (B = -0.456 [P < .001]; B = -0.268 [P < .001]) and anxiety (B = -0.388 [P < .001]; B = -0.284 [P < .001]) for emerging adults. Conclusions. Cohesive and affectively strong personal networks promote resiliency to common mental health challenges during periods of crisis, particularly for emerging adults whose social roles and relationships were disrupted during a critical period of development. (Am J Public Health. Published online ahead of print November 10, 2023:e1-e10. https://doi.org/10.2105/AJPH.2023.307426).

Pandemic Precarity: COVID-19's Impact on Mexican and Central American Immigrant Families

Objective

The study examines the association of gender, parenthood, and marriage with reports of perceived pandemic precarity among Mexican and Central American immigrants during the COVID-19 pandemic (Fall 2020) to understand predictors of vulnerability in periods of crisis.

Background

Latinos/as, immigrants, parents, and women have faced significant challenges during the COVID-19 pandemic. Family structure, along with social expectations for gender (i.e., self-sacrificing femininity for women and hegemonic masculinity for men), parenthood, and marriage may explain perceptions of pandemic precarity - defined as the material deprivation and economic anxiety resulting from the COVID-19 pandemic.

Method

This study used data from the Hispanic COVID-19 Rapid Response Study (n=400), a follow-up of the VidaSana Study of Mexican and Central American immigrants, to examine how family structure is associated with pandemic precarity (i.e., food, housing, and economic insecurity). Using linear regression models, average marginal effects (AMEs), and tests for group differences we investigate the independent and interactive effects of gender, parenthood, and marriage on pandemic precarity.

Results

Men and parents reported the highest pandemic precarity. Fathers reported higher pandemic precarity than mothers. For men, marriage is associated with greater precarity, and for women, marriage is associated with less precarity, yet marriage increased precarity for those without children.

Conclusion

We discuss the importance and implications of examining gender along with family structure to understand how immigrant families were faring in response to the pandemic.

Perceived discrimination and mental health among African American and Caribbean Black adolescents: ethnic differences in processes and effects

Objectives: Although the relationship between perceived discrimination and mental health among Black youth is well-documented, the mechanisms underlying this association remain unclear. Drawing from the stress process model, this study examines two psychosocial mediators - self-esteem and self-efficacy - in the association between perceived discrimination and mental health among African American and Caribbean Black adolescents. This research addresses three primary research questions: First, how is perceived discrimination associated with mental health? Second, to what extent do self-esteem and self-efficacy mediate the relationship between perceived discrimination and mental health? Finally, do these relationships and processes differ between African American and Caribbean Black adolescents?Design: Data for these analyses come from the National Survey of American Life - Adolescent Supplement. We use generalized structural equation modeling to examine relationships among perceived discrimination, psychosocial resources, and mental health.Results: For both African American and Caribbean Black adolescents, more frequent perceptions of discriminatory events were associated with greater depressive symptoms and a higher likelihood of having an anxiety disorder diagnosis. However, the association between perceived discrimination and depressive symptoms was significantly stronger for Caribbean Black adolescents. Generally, self-esteem and self-efficacy were found to be significant mediators in the association between perceived discrimination and mental health, although mechanisms varied between African American and Caribbean Black youth.Conclusion: African American and Caribbean Black adolescents are highly susceptible to experiences of discrimination that negatively affect their mental health. Heterogeneity among Black youth populations must be considered when developing interventions to reduce exposure to and the effects of discrimination among these adolescents.

Association of length of hospital stay with delay to surgical fixation of hip fracture

Background:

Previous research has shown increases in length of stay (LOS), morbidity and mortality when the standard for surgical fixation of hip fracture of 48 hours is not met. However, few investigators have analyzed LOS as a primary outcome, and most used time of diagnosis as opposed to time of fracture as the reference point. We examined the effect of time to surgical fixation of hip fracture, measured from time of fracture, on length of hospital stay; the secondary outcome was average 1-year mortality.

Methods:

We conducted a retrospective cohort study of patients presenting to 1 of 2 tertiary care centres in St. John’s, Newfoundland and Labrador, Canada, with a hip fracture from Jan. 1, 2014, to Dec. 31, 2018. We analyzed 3 groups based on timing of surgical fixation after fracture: less than 24 hours (group 1), 24–48 hours (group 2) and more than 48 hours (group 3). We assessed statistical significance using 1-way analysis of variance.

Results:

Of the 692 patients included in the study, 212 (30.6%) were in group 1, 360 (52.0%) in group 2 and 120 (17.3%) in group 3. A delay to surgical fixation exceeding 48 hours was associated with a significantly longer LOS, by an average of 2.9 and 2.8 days compared to groups 1 and 2, respectively (p = 0.04); there was no significant difference in LOS between groups 1 and 2. A significant difference in average 1-year mortality was observed between groups 1 (11%) and 3 (26%) (p = 0.004), and groups 2 (13%) and 3 (p = 0.009).

Conclusion:

Surgical fixation beyond 48 hours after hip fracture resulted in significantly increased LOS and 1-year mortality. Further research should be conducted to evaluate reasons for delays to surgery and the effects of these delays on time to surgical fixation as measured from time of fracture.

Examining the Relationship between Discrimination and Prescription Drug Misuse: Findings from a National Survey of Black Americans

Background: Research shows that substance use may be a way individuals cope with psychosocial stressors. Less is known about whether discrimination contributes to prescription drug misuse. Methods: Using a national sample of Black Americans, we examined whether two psychosocial stressors (i.e., everyday and lifetime major discrimination) were associated with lifetime prescription drug misuse (i.e., opioids, tranquilizers, sedatives, or stimulants). Results: Our logistic regression models separately examining the influence of everyday and major discrimination controlling for relevant demographic, health, and other drug use variables showed that only everyday discrimination was associated with higher odds of prescription drug misuse. In the model simultaneously considering both types of discrimination, only unit increases in everyday discrimination were associated with higher odds of prescription drug misuse. Conclusions: Encounters with everyday discrimination may be an important psychosocial stressor linked to prescription drug misuse in Black adults and possibly other racial-ethnic minorities. Intervention strategies aiming to reduce prescription drug misuse should consider developing ways to curb the negative health-related consequences of discriminatory experiences. Strategies to combat discrimination-related prescription drug misuse and limitations of this study are discussed.

Nanos gigantium humeris insidentes: old papers informing new research into Toxoplasma gondii

Since Nicolle, Manceaux and Splendore first described Toxoplasma gondii as a parasite of rodents and rabbits in the early 20th century, a diverse and vigorous research community has been built around studying this fascinating intracellular parasite. In addition to its importance as a pathogen of humans, livestock and wildlife, modern researchers are attracted to T. gondii as a facile experimental system to study many aspects of evolutionary biology, cellular biology, host-microbe interactions, and host immunity. For new researchers entering the field, the extensive literature describing the biology of the parasite, and the interactions with its host, can be daunting. In this review, we examine four foundational studies that describe various aspects of T. gondii biology, presenting a 'journal club'-style analysis of each. We have chosen a paper that established the beguiling life cycle of the parasite (Hutchison et al., 1971), a paper that described key features of its cellular biology that the parasite shares with related organisms (Gustafson et al., 1954), a paper that characterised the origin of the unique compartment in which the parasite resides within host cells (Jones and Hirsch, 1972), and a paper that established a key mechanism in the host immune response to parasite infection (Pfefferkorn, 1984). These interesting and far-reaching studies set the stage for subsequent research into numerous facets of parasite biology. As well as providing new researchers with an entry point into the literature surrounding the parasite, revisiting these studies can remind us of the roots of our discipline, how far we have come, and the new directions in which we might head.

Black-White disparities in women's physical health: The role of socioeconomic status and racism-related stressors

Black women have elevated rates of multiple physical illnesses and conditions when compared to White women - disparities that are only partially explained by socioeconomic status (SES). Consequently, scholars have called for renewed attention to the significance of racism-related stress in explaining Black-White disparities in women's physical health. Drawing on the biopsychosocial model of racism as a stressor and the intersectionality perspective, this study examines the extent to which SES and racism-related stressors - i.e., discrimination, criminalization, and adverse neighborhood conditions - account for disparities in self-rated physical health and chronic health conditions between Black and White women. Results indicate that Black women have lower SES and report greater exposure to racism-related stressors across all domains. Moreover, I find that SES and racism-related stressors jointly account for more than 90% of the Black-White disparity in women's self-rated physical health and almost 50% of the Black-White disparity in chronic health conditions. Theoretical and policy implications of these findings are discussed.

Exploration of PCORnet Data Resources for Assessing Use of Molecular-Guided Cancer Treatment

PURPOSE

Examine the ability of PCORnet data resources to investigate molecular-guided cancer treatment.

PATIENTS AND METHODS

Patients (N = 86,154) had single primary solid tumors (diagnosed 2013-2017) from hospital oncology registries linked to the PCORnet Common Data Model (CDM) at 11 medical institutions. Molecular and anatomic test procedures and oral and infused therapies were identified with Current Procedural Terminology (CPT) and Healthcare Common Procedure Coding System (HCPCS) codes, RxNorm Concept Unique Identifier, and National Drug Codes from CDM tables. Chart review (2 institutions, n = 213) for advanced colorectal cancer and Medicare claims linkages (7 institutions, n = 1,731) for breast cancer explored options for increasing electronic data capture.

RESULTS

Molecular testing prevalence detected via analyte-specific molecular CPT/HCPCS codes was 5.5% (n = 4,784); for the nonspecific anatomic pathology codes, for which only some testing is performed to guide therapy selection, it was an additional 44.8% (n = 38,610). Molecular-guided therapy prevalence was 5% (n = 4,289). Testing and treatment were most common with stage IV disease and varied across cancer types and study institutions (testing, 0%-10.4%; treatment, 0.8%-8.4%). Therapy-concordant test results were found in charts for all 36 treated patients with colorectal cancer at the 2 institutions, 3 (8.3%) of whom received treatment outside the institution. Breast cancer Medicare claims linkage increased rates of identified testing from 62.7%-98.9% and treatment from 3.9%-8.2%.

CONCLUSION

Although a minority of patients received molecular-guided therapies, the majority had testing that could guide cancer treatment. Claims data extended electronic data capture for therapies and test orders but often was uninformative for types of test ordered. Test results continue to require text data curation from narrative pathology reports.

Substrate-mediated regulation of the arginine transporter of Toxoplasma gondii

Intracellular parasites, such as the apicomplexan Toxoplasma gondii, are adept at scavenging nutrients from their host. However, there is little understanding of how parasites sense and respond to the changing nutrient environments they encounter during an infection. TgApiAT1, a member of the apicomplexan ApiAT family of amino acid transporters, is the major uptake route for the essential amino acid L-arginine (Arg) in T. gondii. Here, we show that the abundance of TgApiAT1, and hence the rate of uptake of Arg, is regulated by the availability of Arg in the parasite's external environment, increasing in response to decreased [Arg]. Using a luciferase-based 'biosensor' strain of T. gondii, we demonstrate that the expression of TgApiAT1 varies between different organs within the host, indicating that parasites are able to modulate TgApiAT1-dependent uptake of Arg as they encounter different nutrient environments in vivo. Finally, we show that Arg-dependent regulation of TgApiAT1 expression is post-transcriptional, mediated by an upstream open reading frame (uORF) in the TgApiAT1 transcript, and we provide evidence that the peptide encoded by this uORF is critical for mediating regulation. Together, our data reveal the mechanism by which an apicomplexan parasite responds to changes in the availability of a key nutrient.

Recent achievements and doors opened for coccidian parasite research and development through transcriptomics of enteric sexual stages

The Coccidia is the largest group of parasites within the Apicomplexa, a phylum of unicellular, obligate parasites characterized by the possession of an apical complex of organelles and structures in the asexual stages of their life cycles, as well as by a sexual reproductive phase that occurs enterically in host animals. Coccidian sexual reproduction involves morphologically distinct microgametes and macrogametes that combine to form a diploid zygote and, ultimately, following meiosis and mitosis, haploid, infectious sporozoites, inside sporocysts within an oocyst. Recent transcriptomic analyses have identified genes involved in coccidian sexual stage development and reproduction, including genes encoding for microgamete- and macrogamete-specific proteins with roles in gamete motility, fusion and fertilization, and in the formation of the resilient oocyst wall that allows coccidians to persist for long periods in the environment. Transcriptomics has also provided important clues about the regulation of gene expression in the transformation of parasites from one developmental stage to the next, a complex sequence of events that may involve transcription factors such as the apicomplexan Apetala2 (ApiAP2) family, alternative splicing, regulatory RNAs and MORC (a microrchida homologue and regulator of sexual stage development in Toxoplasma gondii). The molecular dissection of coccidian sexual development and reproduction by transcriptomic analyses may lead to the development of novel transmission-blocking strategies.

Control of human toxoplasmosis

Toxoplasmosis is caused by Toxoplasma gondii, an apicomplexan parasite that is able to infect any nucleated cell in any warm-blooded animal. Toxoplasma gondii infects around 2 billion people and, whilst only a small percentage of infected people will suffer serious disease, the prevalence of the parasite makes it one of the most damaging zoonotic diseases in the world. Toxoplasmosis is a disease with multiple manifestations: it can cause a fatal encephalitis in immunosuppressed people; if first contracted during pregnancy, it can cause miscarriage or congenital defects in the neonate; and it can cause serious ocular disease, even in immunocompetent people. The disease has a complex epidemiology, being transmitted by ingestion of oocysts that are shed in the faeces of definitive feline hosts and contaminate water, soil and crops, or by consumption of intracellular cysts in undercooked meat from intermediate hosts. In this review we examine current and future approaches to control toxoplasmosis, which encompass a variety of measures that target different components of the life cycle of T. gondii. These include: education programs about the parasite and avoidance of contact with infectious stages; biosecurity and sanitation to ensure food and water safety; chemo- and immunotherapeutics to control active infections and disease; prophylactic options to prevent acquisition of infection by livestock and cyst formation in meat; and vaccines to prevent shedding of oocysts by definitive feline hosts.

Arthroscopic Bone Grafting and Arthrodesis of Partial Lunotriquetral Coalition

Background  Lunotriquetal coalition is the most common carpal coalition that can be symptomatic if trauma disrupts the syndesmosis or synchondrosis or if degenerative changes develop between the abnormal articulating surfaces. Case Description  A 15-year-old boy presented with a symptomatic lunotriquetral coalition after a fall 2 years prior. Following appropriate investigation, he was managed via arthroscopic debridement, bone grafting, and lunotriquetral arthrodesis. Literature Review  The majority of symptomatic lunotriquetral coalitions have been managed with open arthrodesis. There is only one prior report of arthroscopic arthrodesis of this articulation that did not utilize bone graft. Relevance  This report details the procedure to allow arthroscopic lunotriquetral arthrodesis with bone grafting, conveying osteogenic properties, and encouraging incorporation at the fusion site while maintaining the dorsal ligaments.

Treatment of mice with S4B6 IL-2 complex prevents lethal toxoplasmosis via IL-12- and IL-18-dependent interferon-gamma production by non-CD4 immune cells

Toxoplasmic encephalitis is an AIDS-defining condition. The decline of IFN-γ-producing CD4⁺ T cells in AIDS is a major contributing factor in reactivation of quiescent Toxoplasma gondii to an actively replicating stage of infection. Hence, it is important to characterize CD4-independent mechanisms that constrain acute T. gondii infection. We investigated the in vivo regulation of IFN-γ production by CD8⁺ T cells, DN T cells and NK cells in response to acute T. gondii infection. Our data show that processing of IFN-γ by these non-CD4 cells is dependent on both IL-12 and IL-18 and the secretion of bioactive IL-18 in response to T. gondii requires the sensing of viable parasites by multiple redundant inflammasome sensors in multiple hematopoietic cell types. Importantly, our results show that expansion of CD8⁺ T cells, DN T cells and NK cell by S4B6 IL-2 complex pre-treatment increases survival rates of mice infected with T. gondii and this is dependent on IL-12, IL-18 and IFN-γ. Increased survival is accompanied by reduced pathology but is independent of expansion of T_Reg cells or parasite burden. This provides evidence for a protective role of IL2C-mediated expansion of non-CD4 cells and may represent a promising lead to adjunct therapy for acute toxoplasmosis.

Differential Vulnerability to Perceived Discrimination Between African American and Caribbean Black Adolescents: The Role of Parental Nativity Status

An emerging body of research finds that African American and Caribbean Black adolescents are highly susceptible to discrimination, which negatively affects their mental health. Exposure to discrimination appears to be more consequential for mental health among Caribbean Black adolescents; however, past research investigating the differential impact of perceived discrimination on the mental health of African American and Caribbean Black adolescents has failed to take into account parental nativity status. Using data from the National Survey of American Life-Adolescent Supplement (NSAL-A), 2001-2004, this research examines differences in mental health profiles among African American adolescents (n = 783) and Caribbean Black adolescents with US-born (n = 216) and immigrant parents (n = 144) and differential vulnerability to perceptions of discrimination. Findings suggest that Caribbean Black adolescents with immigrant parents report fewer depressive symptoms than African American adolescents. Caribbean Black adolescents with immigrant parents also perceive lower levels of discrimination than Caribbean Black adolescents with US-born parents. Generally, greater perceptions of discrimination were associated with diminished mental health among all adolescents; however, relative to African American adolescents, associations between perceived discrimination and both mental health indicators were augmented among Caribbean Black adolescents with immigrant parents. No differences were observed between African American adolescents and Caribbean Black adolescents with US-born parents. Theoretical and policy implications of these findings are discussed.

Interosseous Membrane Reconstruction Utilizing Flexor Digitorum Superficialis Autograft

Interosseous membrane (IOM) deficiency results in longitudinal radioulnar instability, and may result in proximal radial migration, increased radiocapitellar contact, limitations in forearm rotation, ulnocarpal instability, and ulna-sided pain. A number of reconstruction methods have been posited-however, few have been implemented in vivo. We describe a 2-bundle method of IOM reconstruction, utilizing flexor digitorum superficialis autograft. This technique has the benefits of utilizing a locally available and robust autograft with minimal donor-site morbidity, obviating the concerns associated with synthetic grafts or bone-patella tendon-bone constructs. It also replicates the nonisometric nature of the native IOM. We also present long-term results of a patient who underwent IOM reconstruction utilizing this method, following a cadaveric feasibility study.

An experimental genetically attenuated live vaccine to prevent transmission of Toxoplasma gondii by cats

Almost any warm-blooded creature can be an intermediate host for Toxoplasma gondii. However, sexual reproduction of T. gondii occurs only in felids, wherein fertilisation of haploid macrogametes by haploid microgametes, results in diploid zygotes, around which a protective wall develops, forming unsporulated oocysts. Unsporulated oocysts are shed in the faeces of cats and meiosis gives rise to haploid sporozoites within the oocysts. These, now infectious, sporulated oocysts contaminate the environment as a source of infection for people and their livestock. RNA-Seq analysis of cat enteric stages of T. gondii uncovered genes expressed uniquely in microgametes and macrogametes. A CRISPR/Cas9 strategy was used to create a T. gondii strain that exhibits defective fertilisation, decreased fecundity and generates oocysts that fail to produce sporozoites. Inoculation of cats with this engineered parasite strain totally prevented oocyst excretion following infection with wild-type T. gondii, demonstrating that this mutant is an attenuated, live, transmission-blocking vaccine.

Establishment of an in vitro chicken epithelial cell line model to investigate Eimeria tenella gamete development

Background

Eimeria tenella infection leads to acute intestinal disorders responsible for important economic losses in poultry farming worldwide. The life-cycle of E. tenella is monoxenous with the chicken as the exclusive host; infection occurs in caecal epithelial cells. However, in vitro, the complete life-cycle of the parasite has only been propagated successfully in primary chicken kidney cells, which comprise undefined mixed cell populations; no cell line model has been able to consistently support the development of the sexual stages of the parasite. We therefore sought to develop a new model to study E. tenella gametogony in vitro using a recently characterised chicken cell line (CLEC-213) exhibiting an epithelial cell phenotype.

Methods

CLEC-213 were infected with sporozoites from a precocious strain or with second generation merozoites (merozoites II) from wild type strains. Sexual stages of the parasite were determined both at the gene and protein levels.

Results

To our knowledge, we show for the first time in CLEC-213, that sporozoites from a precocious strain of E. tenella were able to develop to gametes, as verified by measuring gene expression and by using antibodies to a microgamete-specific protein (EtFOA1: flagellar outer arm protein 1) and a macrogamete-specific protein (EtGAM-56), but oocysts were not observed. However, both gametes and oocysts were observed when cells were infected with merozoites II from wild type strains, demonstrating that completion of the final steps of the parasite cycle is possible in CLEC-213 cells.

Conclusion

The epithelial cell line CLEC-213 constitutes a useful avian tool for studying Eimeria epithelial cell interactions and the effect of drugs on E. tenella invasion, merogony and gametogony.

Cationic amino acid transporters play key roles in the survival and transmission of apicomplexan parasites

Apicomplexans are obligate intracellular parasites that scavenge essential nutrients from their hosts via transporter proteins on their plasma membrane. The identities of the transporters that mediate amino acid uptake into apicomplexans are unknown. Here we demonstrate that members of an apicomplexan-specific protein family-the Novel Putative Transporters (NPTs)-play key roles in the uptake of cationic amino acids. We show that an NPT from Toxoplasma gondii (TgNPT1) is a selective arginine transporter that is essential for parasite survival and virulence. We also demonstrate that a homologue of TgNPT1 from the malaria parasite Plasmodium berghei (PbNPT1), shown previously to be essential for the sexual gametocyte stage of the parasite, is a cationic amino acid transporter. This reveals a role for cationic amino acid scavenging in gametocyte biology. Our study demonstrates a critical role for amino acid transporters in the survival, virulence and life cycle progression of these parasites.

RNA Seq analysis of the Eimeria tenella gametocyte transcriptome reveals clues about the molecular basis for sexual reproduction and oocyst biogenesis

Background

The protozoan Eimeria tenella is a common parasite of chickens, causing avian coccidiosis, a disease of on-going concern to agricultural industries. The high prevalence of E. tenella can be attributed to the resilient oocyst stage, which is transmitted between hosts in the environment. As in related Coccidia, development of the eimerian oocyst appears to be dependent on completion of the parasite’s sexual cycle. RNA Seq transcriptome profiling offers insights into the mechanisms governing the biology of E. tenella sexual stages (gametocytes) and the potential to identify targets for blocking parasite transmission.

Results

Comparisons between the sequenced transcriptomes of E. tenella gametocytes and two asexual developmental stages, merozoites and sporozoites, revealed upregulated gametocyte transcription of 863 genes. Many of these genes code for proteins involved in coccidian sexual biology, such as oocyst wall biosynthesis and fertilisation, and some of these were characterised in more depth. Thus, macrogametocyte-specific expression and localisation was confirmed for two proteins destined for incorporation into the oocyst wall, as well as for a subtilisin protease and an oxidoreductase. Homologues of an oocyst wall protein and oxidoreductase were found in the related coccidian, Toxoplasma gondii, and shown to be macrogametocyte-specific. In addition, a microgametocyte gamete fusion protein, EtHAP2, was discovered.

Conclusions

The need for novel vaccine candidates capable of controlling coccidiosis is rising and this panel of gametocyte targets represents an invaluable resource for development of future strategies to interrupt parasite transmission, not just in Eimeria but in other Coccidia, including Toxoplasma, where transmission blocking is a relatively unexplored strategy.

Electronic supplementary material

The online version of this article (doi:10.1186/s12864-015-1298-6) contains supplementary material, which is available to authorized users.

Asexual expansion of Toxoplasma gondii merozoites is distinct from tachyzoites and entails expression of non-overlapping gene families to attach, invade, and replicate within feline enterocytes

Background

The apicomplexan parasite Toxoplasma gondii is cosmopolitan in nature, largely as a result of its highly flexible life cycle. Felids are its only definitive hosts and a wide range of mammals and birds serve as intermediate hosts. The latent bradyzoite stage is orally infectious in all warm-blooded vertebrates and establishes chronic, transmissible infections. When bradyzoites are ingested by felids, they transform into merozoites in enterocytes and expand asexually as part of their coccidian life cycle. In all other intermediate hosts, however, bradyzoites differentiate exclusively to tachyzoites, and disseminate extraintestinally to many cell types. Both merozoites and tachyzoites undergo rapid asexual population expansion, yet possess different effector fates with respect to the cells and tissues they develop in and the subsequent stages they differentiate into.

Results

To determine whether merozoites utilize distinct suites of genes to attach, invade, and replicate within feline enterocytes, we performed comparative transcriptional profiling on purified tachyzoites and merozoites. We used high-throughput RNA-Seq to compare the merozoite and tachyzoite transcriptomes. 8323 genes were annotated with sequence reads across the two asexually replicating stages of the parasite life cycle. Metabolism was similar between the two replicating stages. However, significant stage-specific expression differences were measured, with 312 transcripts exclusive to merozoites versus 453 exclusive to tachyzoites. Genes coding for 177 predicted secreted proteins and 64 membrane- associated proteins were annotated as merozoite-specific. The vast majority of known dense-granule (GRA), microneme (MIC), and rhoptry (ROP) genes were not expressed in merozoites. In contrast, a large set of surface proteins (SRS) was expressed exclusively in merozoites.

Conclusions

The distinct expression profiles of merozoites and tachyzoites reveal significant additional complexity within the T. gondii life cycle, demonstrating that merozoites are distinct asexual dividing stages which are uniquely adapted to their niche and biological purpose.

Electronic supplementary material

The online version of this article (doi:10.1186/s12864-015-1225-x) contains supplementary material, which is available to authorized users.

Treatment of postoperative lower extremity wounds using human fibroblast-derived dermis: a retrospective analysis

Human fibroblast-derived dermis skin substitute is a well-studied treatment for diabetic foot ulcers; however, no case series currently exist for its use in healing postoperative wounds of the lower extremity. A retrospective analysis was conducted on 32 lower extremity postoperative wounds treated weekly with human fibroblast-derived dermis skin substitute. Postoperative wounds were defined as a wound resulting from an open partial foot amputation, surgical wound dehiscence, or nonhealing surgical wound of the lower extremity. Wound surface area was calculated at 4 and 12 weeks or until wound closure if prior to 12 weeks. Postoperative wounds treated with weekly applications showed mean improvement in surface area reduction of 63.6% at 4 weeks and 96.1% at 12 weeks. More than 56% of all wounds healed prior to the 12-week endpoint. Additionally, only one adverse event was noted in this group. This retrospective review supports the use of human fibroblast-derived dermis skin substitute in the treatment of postoperative lower extremity wounds. This advanced wound care therapy aids in decreased total healing time and increased rate of healing for not only diabetic foot wounds but also postoperative wounds of the lower extremity, as demonstrated by this retrospective review.

A selective review of advances in coccidiosis research

Coccidiosis is a widespread and economically significant disease of livestock caused by protozoan parasites of the genus Eimeria. This disease is worldwide in occurrence and costs the animal agricultural industry many millions of dollars to control. In recent years, the modern tools of molecular biology, biochemistry, cell biology and immunology have been used to expand greatly our knowledge of these parasites and the disease they cause. Such studies are essential if we are to develop new means for the control of coccidiosis. In this chapter, selective aspects of the biology of these organisms, with emphasis on recent research in poultry, are reviewed. Topics considered include taxonomy, systematics, genetics, genomics, transcriptomics, proteomics, transfection, oocyst biogenesis, host cell invasion, immunobiology, diagnostics and control.

Classification of congenital anomalies of the hand and upper limb: development and assessment of a new system

The Oberg, Manske, and Tonkin (OMT) classification of congenital hand and upper limb anomalies was proposed in 2010 as a replacement for the Swanson International Federation of Societies for Surgery of the Hand classification system, which has been the accepted system of classification for the international surgical community since 1976. The OMT system separates malformations from deformations and dysplasias. Malformations are subdivided according to the axis of formation and differentiation that is primarily affected and whether the anomalies involve the whole limb or the hand plate. This review outlines the development of classification systems and explores the difficulty of incorporating our current knowledge of limb embryogenesis at a molecular level into current systems. An assessment of the efficacy of the OMT classification demonstrates acceptable inter- and intraobserver reliability. A prospective review of 101 patients confirms that all diagnoses could be classified within the OMT system. Consensus expert opinion allowed classification of those conditions for which there is not a clear understanding of the mechanism of dysmorphology. A refined and expanded OMT classification is presented.

Dislocation of the fifth metatarsal base following partial fourth and fifth ray amputation: a case report

This case report presents a rare postoperative dislocation of the fifth metatarsal base following a healed open partial fourth and fifth ray amputation of a 62-year-old male veteran with poorly controlled diabetes mellitus. The dislocated fifth metatarsal base subsequently created a chronic ulceration and an inhibition of normal gait. The patient was taken to the operating room where the fifth metatarsal base was resected with transfer of the peroneus brevis tendon to the cuboid to maintain biomechanical stability.

Stage-specific expression of protease genes in the apicomplexan parasite, Eimeria tenella

Background

Proteases regulate pathogenesis in apicomplexan parasites but investigations of proteases have been largely confined to the asexual stages of Plasmodium falciparum and Toxoplasma gondii. Thus, little is known about proteases in other Apicomplexa, particularly in the sexual stages. We screened the Eimeria tenella genome database for proteases, classified these into families and determined their stage specific expression.

Results

Over forty protease genes were identified in the E. tenella genome. These were distributed across aspartic (three genes), cysteine (sixteen), metallo (fourteen) and serine (twelve) proteases. Expression of at least fifteen protease genes was upregulated in merozoites including homologs of genes known to be important in host cell invasion, remodelling and egress in P. falciparum and/or T. gondii. Thirteen protease genes were specifically expressed or upregulated in gametocytes; five of these were in two families of serine proteases (S1 and S8) that are over-represented in the coccidian parasites, E. tenella and T. gondii, distinctive within the Apicomplexa because of their hard-walled oocysts. Serine protease inhibitors prevented processing of EtGAM56, a protein from E. tenella gametocytes that gives rise to tyrosine-rich peptides that are incorporated into the oocyst wall.

Conclusion

Eimeria tenella possesses a large number of protease genes. Expression of many of these genes is upregulated in asexual stages. However, expression of almost one-third of protease genes is upregulated in, or confined to gametocytes; some of these appear to be unique to the Coccidia and may play key roles in the formation of the oocyst wall, a defining feature of this group of parasites.

Evidence-based indications for distraction ankle arthroplasty

BACKGROUND

The purpose of this study was to review the literature to provide a comprehensive description of the Level of Evidence (LOE) available to support the operative technique of distraction ankle arthroplasty for the current generally accepted indications and make a grade of recommendation for each.

METHODS

A comprehensive review of the literature was performed (November 2010 to January 2011) using the PubMed database. The abstracts from these searches were reviewed to isolate literature that described therapeutic studies investigating the results of distraction ankle arthroplasty. All articles were reviewed and assigned a classification (I-V) of Level of Evidence. An analysis of the literature reviewed was used to assign a Grade of Recommendation for each current generally accepted indication for distraction ankle arthroplasty.

RESULTS

There is insufficient evidence based literature (Grade I) to support or refute the procedure for either: post-traumatic ankle arthritis, arthritis associated with ligamentous instability, primary degenerative joint disease, chondrolysis, deformity associated with arthritis, osteochondral defects and congenital ankle abnormalities.

CONCLUSION

Inadequate evidence based literature exists to support or refute all currently accepted indications for distraction ankle arthroplasty and further high quality, scientific studies are needed upgrade to these recommendations.

Eimeripain, a cathepsin B-like cysteine protease, expressed throughout sporulation of the apicomplexan parasite Eimeria tenella

The invasion and replication of Eimeria tenella in the chicken intestine is responsible for avian coccidiosis, a disease that has major economic impacts on poultry industries worldwide. E. tenella is transmitted to naïve animals via shed unsporulated oocysts that need contact with air and humidity to form the infectious sporulated oocysts, which contain the first invasive form of the parasite, the sporozoite. Cysteine proteases (CPs) are major virulence factors expressed by protozoa. In this study, we show that E. tenella expresses five transcriptionally regulated genes encoding one cathepsin L, one cathepsin B and three cathepsin Cs. Biot-LC-LVG-CHN₂, a cystatin derived probe, tagged eight polypeptides in unsporulated oocysts but only one in sporulated oocysts. CP-dependant activities were found against the fluorescent substrates, Z-FR-AMC and Z-LR-AMC, throughout the sporulation process. These activities corresponded to a cathepsin B-like enzyme since they were inhibited by CA-074, a specific cathepsin B inhibitor. A 3D model of the catalytic domain of the cathepsin B-like protease, based on its sequence homology with human cathepsin B, further confirmed its classification as a papain-like protease with similar characteristics to toxopain-1 from the related apicomplexan parasite, Toxoplasma gondii; we have, therefore, named the E. tenella cathepsin B, eimeripain. Following stable transfection of E. tenella sporozoites with a plasmid allowing the expression of eimeripain fused to the fluorescent protein mCherry, we demonstrated that eimeripain is detected throughout sporulation and has a punctate distribution in the bodies of extra- and intracellular parasites. Furthermore, CA-074 Me, the membrane-permeable derivative of CA-074, impairs invasion of epithelial MDBK cells by E. tenella sporozoites. This study represents the first characterization of CPs expressed by a parasite from the Eimeria genus. Moreover, it emphasizes the role of CPs in transmission and dissemination of exogenous stages of apicomplexan parasites.

Correction of varus heel pad in patients with Syme's amputations

Syme's amputations can provide a reliable alternative to more proximal amputations, but they are not without their occasional complication. Varus heel pad migration has been well documented as a complication following Syme's amputations. We describe a technique of resection of soft tissue and bone combined with anchoring of the lateral band of the plantar fascia in order to treat patients with the complication of varus heel pad migration.

The role of the P2X₇ receptor in infectious diseases

ATP is an extracellular signal for the immune system, particularly during an inflammatory response. It is sensed by the P2X₇ receptor, the expression of which is upregulated by pro-inflammatory cytokines. Activation of the P2X₇ receptor opens a cation-specific channel that alters the ionic environment of the cell, activating several pathways, including (i) the inflammasome, leading to production of IL-1β and IL-18; (ii) the stress-activated protein kinase pathway, resulting in apoptosis; (iii) the mitogen-activated protein kinase pathway, leading to generation of reactive oxygen and nitrogen intermediates; and (iv) phospholipase D, stimulating phagosome-lysosome fusion. The P2X₇ receptor can initiate host mechanisms to remove pathogens, most particularly those that parasitise macrophages. At the same time, the P2X₇ receptor may be subverted by pathogens to modulate host responses. Moreover, recent genetic studies have demonstrated significant associations between susceptibility or resistance to parasites and bacteria, and loss-of-function or gain-of-function polymorphisms in the P2X₇ receptor, underscoring its importance in infectious disease.

Community-acquired pneumonia due to Panton-Valentine leukocidin-producing Staphylococcus aureus in an HIV-2-infected patient

Pneumonia caused by Panton-Valentine leukocidin-producing Staphylococcus aureus is associated with a high fatality rate. There have been few reported cases in HIV-1-co-infected patients. Here we report a fatal case of severe community-acquired pneumonia caused by Panton-Valentine leukocidin-producing S. aureus in a 45-year-old woman with HIV-2 infection.

Early combined neurosurgery and orthopaedic surgery in Neonatal Brachial Plexus Palsy

Three cases are presented in which neurosurgical reconstruction of a Neonatal Brachial Plexus Palsy was combined with orthopaedic reconstruction of a posterior glenohumeral dislocation. The authors believe that a combined procedure is indicated if the neurological deficit meets the criteria for neural reconstruction and the complication of a posterior glenohumeral dislocation has occurred prior to nerve surgery. Two children with C5-6 lesions and a third child with a pan-plexus lesion obtained good shoulder function following the combined reconstruction.

Dysregulation of the inflammatory response to the parasite, Toxoplasma gondii, in P2X7 receptor-deficient mice

The P2X(7) receptor (P2X(7)R) is a two transmembrane receptor that is highly expressed on the surface of immune cells. Loss of function polymorphisms in this receptor have been linked to increased susceptibility to intracellular pathogens. P2X(7)R gene knockout (P2X(7)R(-/-); on a C57Bl/6J background), C57Bl/6J and BALB/c mice were infected with the avirulent ME49 strain of the intracellular parasite, Toxoplasma gondii, and susceptibility determined by monitoring weight loss. P2X(7)R(-/-) mice lost significantly more weight than C57Bl/6J mice from day 8p.i. C57Bl/6J, in turn, lost significantly more weight than BALB/c mice. Thus, by day 10p.i., P2X(7)R(-/-) mice had lost 5.7 ± 0.7% of their weight versus 2.4 ± 0.6% for C57Bl/6J mice, whereas BALB/c mice had gained 1.9 ± 0.5%; by day 12p.i., P2X(7)R(-/-) mice had lost 15.1±0.6%, C57Bl/6J had lost 10.1±0.8% and BALB/c had lost 4.8 ± 0.8% of their weight. Neither parasite burden nor liver pathology was greater in the P2X(7)R(-/-) mice than in C57Bl/6J mice but BALB/c mice had significantly smaller numbers of parasites and less pathology in their livers than these strains. Absence of the P2X(7) receptor did not affect IFN-γ, IL-12, IL-1β, monocyte chemoattractant protein-1 (MCP-1) or TNF production. However, both P2X(7)R(-/-) and C57Bl/6J mice produced more IL-1β and TNF than BALB/c mice. There was one important point of differentiation between the P2X(7)R(-/-) and C57Bl/6J mice, namely the significantly enhanced and prolonged production of nitric oxide, accompanied by delayed production of IL-10 in the P2X(7)R-deficient mice.

Chasing the golden egg: vaccination against poultry coccidiosis

Eimeria species, of the Phylum Apicomplexa, cause the disease coccidiosis in poultry, resulting in severe economic losses every year. Transmission of the disease is via the faecal-oral route, and is facilitated by intensive rearing conditions in the poultry industry. Additionally, Eimeria has developed drug resistance against most anticoccidials used today, which, along with the public demand for chemical free meat, has lead to the requirement for an effective vaccine strategy. This review focuses on the history and current status of anticoccidial vaccines, and our work in developing the transmission-blocking vaccine, CoxAbic (Netanya, Israel). The vaccine is composed of affinity-purified antigens from the wall-forming bodies of macrogametocytes of Eimeria maxima, which are proteolytically processed and cross-linked via tyrosine residues to form the environmentally resistant oocyst wall. The vaccine is delivered via maternal immunization, where vaccination of laying hens leads to protection of broiler offspring. It has been extensively tested for efficacy and safety in field trials conducted in five countries and involving over 60 million offspring chickens from immunized hens and is currently the only subunit vaccine against any protozoan parasite to reach the marketplace.

Evidence for associations between the purinergic receptor P2X(7) (P2RX7) and toxoplasmosis

Congenital Toxoplasma gondii infection can result in intracranial calcification, hydrocephalus, and retinochoroiditis. Acquired infection is commonly associated with ocular disease. Pathology is characterized by strong pro-inflammatory responses. Ligation of ATP by purinergic receptor P2X₇, encoded by P2RX7, stimulates pro-inflammatory cytokines and can lead directly to killing of intracellular pathogens. To determine whether P2X₇ plays a role in susceptibility to congenital toxoplasmosis, we examined polymorphisms at P2RX7 in 149 child/parent trios from North America. We found association (FBAT Z scores ±2.429; P= 0.015) between the derived C(+)G(−) allele (f= 0.68; OR= 2.06; 95% CI: 1.14–3.75) at SNP rs1718119 (1068T>C; Thr-348-Ala), and a second synonymous variant rs1621388 in linkage disequilibrium with it, and clinical signs of disease per se. Analysis of clinical sub-groups showed no association with hydrocephalus, with effect sizes for associations with retinal disease and brain calcifications enhanced (OR=3.0 to 4.25; 0.004<P<0.009) when hydrocephalus was removed from the analysis. Association with toxoplasmic retinochoroiditis was replicated (FBAT Z scores ±3.089; P= 0.002) in a small family-based study (60 families; 68 affected offspring) of acquired infection in Brazil, where the ancestral T(+) allele (f= 0.296) at SNP rs1718119 was strongly protective (OR= 0.27; 95% CI: 0.09–0.80). (Words 194)

P2X7 receptor-mediated killing of an intracellular parasite, Toxoplasma gondii, by human and murine macrophages

The P2X7R is highly expressed on the macrophage cell surface, and activation of infected cells by extracellular ATP has been shown to kill intracellular bacteria and parasites. Furthermore, single nucleotide polymorphisms that decrease receptor function reduce the ability of human macrophages to kill Mycobacterium tuberculosis and are associated with extrapulmonary tuberculosis. In this study, we show that macrophages from people with the 1513C (rs3751143, NM_002562.4:c.1487A>C) loss-of-function P2X7R single nucleotide polymorphism are less effective in killing intracellular Toxoplasma gondii after exposure to ATP compared with macrophages from people with the 1513A wild-type allele. Supporting a P2X7R-specific effect on T. gondii, macrophages from P2X7R knockout mice (P2X7R-/-) are unable to kill T. gondii as effectively as macrophages from wild-type mice. We show that P2X7R-mediated T. gondii killing occurs in parallel with host cell apoptosis and is independent of NO production.

Non-archetypal Type II-like and atypical strains of Toxoplasma gondii infecting marsupials of Australia

Australia is geographically isolated and possesses a remarkable diversity of wildlife species. Marsupials are highly susceptible to infection with the cosmopolitan parasite Toxoplasma gondii. Of 46 marsupials screened for T. gondii by multilocus PCR-DNA sequencing at polymorphic genes (B1, SAG3, GRA6, GRA7), 12 were PCR-positive; the majority (67%; 9/12) were infected by non-archetypal Type II-like or atypical strains. Six novel alleles were detected at B1, indicating greater diversity of genotypes than previously envisaged. Two isolates lethal to marsupials, were avirulent to mice. The data support the conclusion that Australia's isolation may have favoured the persistence of non-archetypal ancestral genotypes.

Oocyst wall formation and composition in coccidian parasites

The oocyst wall of coccidian parasites is a robust structure that is resistant to a variety of environmental and chemical insults. This resilience allows oocysts to survive for long periods, facilitating transmission from host to host. The wall is bilayered and is formed by the sequential release of the contents of two specialized organelles - wall forming body 1 and wall forming body 2 - found in the macrogametocyte stage of Coccidia. The oocyst wall is over 90% protein but few of these proteins have been studied. One group is cysteine-rich and may be presumed to crosslink via disulphide bridges, though this is yet to be investigated. Another group of wall proteins is rich in tyrosine. These proteins, which range in size from 8-31 kDa, are derived from larger precursors of 56 and 82 kDa found in the wall forming bodies. Proteases may catalyze processing of the precursors into tyrosine-rich peptides, which are then oxidatively crosslinked in a reaction catalyzed by peroxidases. In support of this hypothesis, the oocyst wall has high levels of dityrosine bonds. These dityrosine crosslinked proteins may provide a structural matrix for assembly of the oocyst wall and contribute to its resilience.

Conservation of proteins involved in oocyst wall formation in Eimeria maxima, Eimeria tenella and Eimeria acervulina

Vaccination with proteins from gametocytes of Eimeria maxima protects chickens, via transfer of maternal antibodies, against infection with several species of Eimeria. Antibodies to E. maxima gametocyte proteins recognise proteins in the wall forming bodies of macrogametocytes and oocyst walls of E. maxima, Eimeria tenella and Eimeria acervulina. Homologous genes for two major gametocyte proteins – GAM56 and GAM82 – were found in E. maxima, E. tenella and E. acervulina. Alignment of the predicted protein sequences of these genes reveals that, as well as sharing regions of tyrosine richness, strong homology exists in their amino-terminal regions, where protective antibodies bind. This study confirms the conservation of the roles of GAM56 and GAM82 in oocyst wall formation and shows that antibodies to gametocyte antigens of E. maxima cross-react with homologous proteins in other species, helping to explain cross-species maternal immunity.

Field application of a subunit vaccine against an enteric protozoan disease

Background

Coccidiosis is a major global veterinary health problem in intensively reared chickens. It is caused by apicomplexan parasites of the genus Eimeria.

Principal Findings

A subunit vaccine composed of purified antigens from the gametocytes of Eimeria maxima was used to stimulate the production and transfer of maternal antibodies between breeding hens and their hatchlings. The vaccine was injected into hens twice before they began laying eggs. Immunization had no adverse affects on egg laying or health of the hens and resulted in high antibody levels throughout the life of the hens. Progeny of immunized hens excreted significantly less oocysts of various species of Eimeria in their faeces than chicks from unvaccinated hens. Furthermore, the offspring of vaccinated hens developed stronger natural immunity to Eimeria, so that they were resistant to challenge infection even at 8 weeks of age, well after all maternal antibodies had left their circulation. Field trials were conducted in South Africa, Brazil and Thailand, involving at least 1 million progeny of vaccinated hens and at least 1 million positive control birds (raised on feed containing anticoccidial drugs or immunized with a live vaccine) in each country. Additionally, trials were carried out in Israel involving 60 million progeny of vaccinated hens and 112 million positive control birds. There were no significant differences in growth rate, feed conversion ratios or mortality in the offspring of vaccinated hens compared with the positive control chickens in any of these countries regardless of different management practices, different breeds of chickens or climate.

Conclusions

These results demonstrate that a vaccine composed of antigens purified from the gametocytes of Eimeria can be used safely and effectively to prevent the deleterious effects of coccidiosis. It is the first subunit vaccine against any protozoan parasite to be successfully applied on a commercial scale.

The immunobiology of the innate response to Toxoplasma gondii

Toxoplasma gondii is a unique intracellular parasite. It can infect a variety of cells in virtually all warm-blooded animals. It has a worldwide distribution and, overall, around one-third of people are seropositive for the parasite, with essentially the entire human population being at risk of infection. For most people, T. gondii causes asymptomatic infection but the parasite can cause serious disease in the immunocompromised and, if contracted for the first time during pregnancy, can cause spontaneous abortion or congenital defects, which have a substantial emotional, social and economic impact. Toxoplasma gondii provokes one of the most potent innate, pro-inflammatory responses of all infectious disease agents. It is also a supreme manipulator of the immune response so that innate immunity to T. gondii is a delicate balance between the parasite and its host involving a coordinated series of cellular interactions involving enterocytes, neutrophils, dendritic cells, macrophages and natural killer cells. Underpinning these interactions is the regulation of complex molecular reactions involving Toll-like receptors, activation of signalling pathways, cytokine production and activation of anti-microbial effector mechanisms including generation of reactive nitrogen and oxygen intermediates.

Muscle architecture and functional anatomy of the pelvic limb of the ostrich (Struthio camelus)

The functional anatomy of the pelvic limb of the ostrich (Struthio camelus) was investigated in order to assess musculoskeletal specialization related to locomotor performance. The pelvic limbs of ten ostriches were dissected and detailed measurements of all muscle tendon units of the pelvic limb were made, including muscle mass, muscle length, fascicle length, pennation angle, tendon mass and tendon length. From these measurements other muscle properties such as muscle volume, physiological cross-sectional area (PCSA), tendon cross-sectional area, maximum isometric muscle force and tendon stress were derived, using standard relationships and published muscle data. Larger muscles tended to be located more proximally and had longer fascicle lengths and lower pennation angles. This led to an expected proximal to distal reduction in total muscle mass. An exception to this trend was the gastrocnemius muscle, which was found to have the largest volume and PCSA and also had the highest capacity for both force and power production. Generally high-power muscles were located more proximally in the limb, while some small distal muscles (tibialis cranialis and flexor perforatus digiti III), with short fibres, were found to have very high force generation capacities. The greatest proportion of pelvic muscle volume was for the hip extensors, while the highest capacity for force generation was observed in the extensors of the ankle, many of which were also in series with long tendons and thus were functionally suited to elastic energy storage.