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In sub-Saharan Africa’s endemic areas for urogenital schistosomiasis, male genital schistosomiasis (MGS) can cause significant morbidity. As part of the Hybridization in UroGenital Schistosomiasis investigation, an MGS sub-study examined a cohort of adult men over a calendar year to better ascertain general infection dynamics and putative zoonotic schistosome transmission. During follow-up, demographic, health and socio-economic data were collected through individual questionnaire interviews. Collected urine and semen were analysed using urine filtration, urine and semen microscopy and molecular DNA analyses of semen. Ten participants with reported MGS-associated symptoms had Schistosoma eggs in their urine and semen at 6-month follow-up, with seven at 12 months. Ten out of 11 participants with Schistosoma haematobium eggs on semen microscopy at baseline had persistent infection at 6-month follow-up, together with 6 new participants, giving an MGS prevalence of 84·2% (n = 19). Two also had Schistosoma mattheei eggs co-infection. Four of the 13 participants at 12-month follow-up had S. haematobium eggs in their semen which were persistent at all the time points. Using semen PCR, 14 participants (73·7%) had Schistosoma infection at 6 months, with only 2 participants being infected for first time. Upon DNA analysis, three participants also had hybrid co-infection at this time point. At 12 months, only 6 participants had Schistosoma infection with no hybrids detected. In summary, like S. haematobium and despite praziquantel treatment, both zoonotic and hybrid schistosomes can continue to cause MGS, which pose a further tangible challenge in future management and control measures.
Urogenital schistosomiasis (UGS) caused by zoonotic or hybrid schistosome infection(s) is an emerging public health concern in Malawi, and we describe a 1-year clinical sub-study with 3 inspection time points for female genital schistosomiasis (FGS) upon selecting 86 women with proven UGS. This sub-study was set within a broader 2-year longitudinal ‘Hybridization in UroGenital Schistosomiasis (HUGS)’ investigation. A detailed cervicovaginal examination with a portable colposcope was conducted, examining cervicovaginal lavage (CVL), cervical swab, cervical biopsy and urine with traditional parasitological and molecular diagnostic methods. At baseline, overt FGS by colposcopy was 72.1%, 64.3% by CVL real-time PCR and 51.2% by both colposcopy and CVL-PCR, noting urine-microscopy could often be negative. Human papillomavirus was detected in 31.0% of the cervical swabs, with 8.3% women also FGS positive by colposcopy and real-time PCR. Over the year, FGS prevalence by colposcopy increased by 32.7% during the study to 84.6%, homogenous yellow and grainy sandy patches being very common in the youngest 18–25 age group, where 51.9% were positive. FGS appears widespread locally and we discuss difficulties in its detection without invasive sampling. In addition to the presence of S. haematobium, S. mattheei was noted alongside key concurrent sexually transmitted infections. From our findings, we point out that improved prevention and management of FGS is required, foremost, better availability and regular accessibility to praziquantel treatment is needed. Furthermore, targeted health education, raised community awareness and dovetailing synergistic public health activities within Sexual and Reproductive Health services and local HIV/AIDS programmes could develop an appropriate holistic health intervention package.
The dhole Cuon alpinus is a large canid that is categorized as Endangered on the IUCN Red List and at risk of global extinction. Information on the spatial distribution of suitable habitat is important for conservation planning but is largely unavailable. We quantified the spatial distribution of potential range as well as the relative probability of dhole occurrence across large parts of the species’ global range. We used the MaxEnt algorithm to produce a multi-scale environmental niche model based on 24 environmental variables and dhole occurrence data from 12 countries. We identified three regions where dhole conservation should be focused: western India, central India, and across the Himalayan foothills through Southeast Asia. Connectivity between suitable areas was poor, so coordinated action among these regions should be a priority. For instance, transboundary dhole conservation initiatives across the Himalayas from southern China, Myanmar, north-east India, Nepal and Bhutan need to be initiated. We also highlight the value of improving dhole population viability on unprotected land and increasing monitoring in the northern parts of its historic distribution, in particular in areas within mainland China.
Distinguishing early domesticates from their wild progenitors presents a significant obstacle for understanding human-mediated effects in the past. The origin of dogs is particularly controversial because potential early dog remains often lack corroborating evidence that can provide secure links between proposed dog remains and human activity. The Tumat Puppies, two permafrost-preserved Late Pleistocene canids, have been hypothesized to have been littermates and early domesticates due to a physical association with putatively butchered mammoth bones. Through a combination of osteometry, stable isotope analysis, plant macrofossil analysis, and genomic and metagenomic analyses, this study exploits the unique properties of the naturally mummified Tumat Puppies to examine their familial relationship and to determine whether dietary information links them to human activities. The multifaceted analysis reveals that the 14,965–14,046 cal yr BP Tumat Puppies were littermates who inhabited a dry and relatively mild environment with heterogeneous vegetation and consumed a diverse diet, including woolly rhinoceros in their final days. However, because there is no evidence of mammoth consumption, these data do not establish a link between the canids and ancient humans.
There is a lack of ethical triage and treatment guidelines for the entrapped and mangled extremity (E&ME) in resource scarce environments: mass casualty incidents, low- to middle- income countries, complex humanitarian emergencies including conflict, and prolonged transport times (RSE).
Objectives:
The aim of this study is to use a modified Delphi (mD) approach to produce statements to develop treatment guidelines of the E&ME in RSE to advance the 2021 WHO EMT Minimum Standards (EMT) treating the E&ME.
Method/Description:
Experts rated their agreement with each statement on a 7- point linear numeric scale. Consensus amongst experts was defined as a standard deviation <= 1. Statements attaining consensus after the first round moved to the final report. Those not attaining consensus moved to the second round in which experts were shown the mean response of the expert panel and their own response for the opportunity to reconsider their rating for that round. Statements attaining consensus after the second round moved to the final report. This process repeated in the third round. Statements attaining consensus moved to the final report. The remaining statements did not attain consensus.
Results/Outcomes:
Seventy-seven experts participated in the first, 75 in the second, and 74 in the third round. Twenty-three statements attained consensus. Twenty-one statements did not attain consensus.
Conclusion:
A Delphi technique was used to establish consensus regarding the numerous complex factors influencing treatment of the E&ME in RSEs. Twenty-three statements attained consensus and can be incorporated into guidelines to advance the EMT treating the E&ME.
This essay is a lightly edited version of a speech I gave at the annual reception of the Conference on Latin American History (CLAH) at the American Historical Association meetings in New York City in January 2025. It was written as a keynote address connected with my acceptance of CLAH’s Distinguished Service Award for 2024. I focus here on what have been the two most critical and intertwined commitments of my roughly five-decade career as a historian of Mexico and Latin America: broad intellectual collaboration across disciplines, academic generations, and national boundaries, and a two-way notion of mentoring. Apart from my own monographic research, these commitments have played out in an array of editorial arenas—academic journals, multi-authored collections, a massive country-level compendium of documents, and a long-running book series—that have remained integral to my intellectual growth and figured importantly in the mentoring of my doctoral students and their mentoring of me. My career trajectory in this regard may well have been a road less travelled and one certainly not for everyone; still, there is a case to be made for giving greater emphasis to broader collaborative strategies of research and dissemination in our work as scholars and teachers of Latin America’s past.
Invasive common reed [Phragmites australis (Cav.) Trin. ex Steud. ssp. australis] has established and dominated Ontario wetlands for decades. The detrimental effects of P. australis invasions on wetland habitats have demanded intervention through aggressive suppression efforts. However, constraints in available control methods to suppress P. australis have led to persistent invasions. To improve P. australis management in wetlands, we investigated remotely piloted aircraft systems (RPASs) as a precision tool for herbicide application. We applied an imazapyr-based herbicide (240 g ai L−1) with a spray-equipped RPAS at selected test sites, marking the first-ever application of its kind in Canada. We then (1) evaluated the efficacy of RPAS-based herbicide application to P. australis and (2) examined the plant community changes 1 yr after the initial herbicide application. We found a >99% reduction in live P. australis stems, along with reductions in species richness (33%), Shannon-Weiner diversity (73%), Simpson’s reciprocal diversity (50%), and Pielou’s evenness (73%) in the year following herbicide application. Plant community changes varied by field site; one wetland underwent a secondary invasion by European frog-bit (Hydrocharis morsus-ranae L.) while the other was dominated by the native spotted jewelweed (Impatiens capensis Meerb.), highlighting the complexities of plant community succession following herbicide application in biodiverse wetlands.
The Institute for Implementation Science Scholars (IS-2) is a dissemination and implementation (D&I) science training and mentoring program. A key component of IS-2 is collaborating and networking. To build knowledge on effective networking and mentoring, this study sought to 1) conduct a social network analysis to determine whether underrepresented scholars have equivalent levels of connection and 2) gain insights into the differences in networking among racial/ethnic subgroups of scholars.
Methods:
Social network survey data were used to select participants based on number of collaborative connections (highest, lowest) and racial/ ethnic category (underrepresented, not underrepresented). Interviews were recorded, transcribed, and coded using an iterative process.
Results:
The sample consisted of eight highly networked scholars, eight less networked scholars, seven from underrepresented racial and ethnic groups, and nine from not underrepresented groups. Qualitative data showed a lack of connection, reluctance to network, and systematic issues including institutional biases as possible drivers of group differences. In addition, scholars provided suggestions on how to overcome barriers to networking and provided insights into how IS-2 has impacted their D&I research and knowledge.
Conclusions:
Underrepresented scholars have fewer network contacts than not underrepresented scholars in the IS-2 training program. It is imperative for leadership to be intentional with mentorship pairing, especially for underrepresented scholars. Future research might include interviews with program leaders to understand how network pairings are built to improve the mentorship experience.
This qualitative study aimed to understand facilitators and barriers to implementation of interventions to improve guideline-concordant antibiotic duration prescribing for pediatric acute otitis media (AOM).
Design:
Clinicians and clinic administrators participated in semi-structured qualitative interviews, and parents of children 2 years of age or older with a recent diagnosis of AOM participated in focus groups. The Practical Robust Implementation and Sustainability Model (PRISM) guided the study. Interviews were analyzed using the Rapid Assessment Process.
Setting:
Denver Health and Hospital Authority (Denver, CO) led the study. Recruitment occurred at Vanderbilt University Medical Center (Nashville, TN) and Washington University in St. Louis Medical Center (St. Louis, MO).
Participants:
Purposeful sampling was used to recruit clinicians and administrators for qualitative interviews. Convenience sampling was used to recruit parents for focus groups.
Results:
Thirty-one participants (15 clinicians, 4 administrators, and 12 parents) engaged in interviews and focus groups. Factors influencing antibiotic prescribing included patient history, years of practice, familiarity with the patient, concerns with patient medication adherence, and practice type. Clinicians endorsed electronic health record modifications and clinician prescribing feedback as methods to improve patient care and reduce the durations of prescribed antibiotics. Suggestions for intervention optimization and education needs were also obtained.
Conclusions:
Findings suggest that clinicians and administrators support reducing prescribed antibiotic durations for AOM and are receptive to the proposed interventions. More education is needed to increase parent awareness about antibiotic stewardship and AOM treatment options.
Clinical trials identifier:
RELAX: Reducing Length of Antibiotics for Children with Ear Infections (RELAX), NCT05608993, https://clinicaltrials.gov/study/NCT05608993.
Identifying persons with HIV (PWH) at increased risk for Alzheimer’s disease (AD) is complicated because memory deficits are common in HIV-associated neurocognitive disorders (HAND) and a defining feature of amnestic mild cognitive impairment (aMCI; a precursor to AD). Recognition memory deficits may be useful in differentiating these etiologies. Therefore, neuroimaging correlates of different memory deficits (i.e., recall, recognition) and their longitudinal trajectories in PWH were examined.
Design:
We examined 92 PWH from the CHARTER Program, ages 45–68, without severe comorbid conditions, who received baseline structural MRI and baseline and longitudinal neuropsychological testing. Linear and logistic regression examined neuroanatomical correlates (i.e., cortical thickness and volumes of regions associated with HAND and/or AD) of memory performance at baseline and multilevel modeling examined neuroanatomical correlates of memory decline (average follow-up = 6.5 years).
Results:
At baseline, thinner pars opercularis cortex was associated with impaired recognition (p = 0.012; p = 0.060 after correcting for multiple comparisons). Worse delayed recall was associated with thinner pars opercularis (p = 0.001) and thinner rostral middle frontal cortex (p = 0.006) cross sectionally even after correcting for multiple comparisons. Delayed recall and recognition were not associated with medial temporal lobe (MTL), basal ganglia, or other prefrontal structures. Recognition impairment was variable over time, and there was little decline in delayed recall. Baseline MTL and prefrontal structures were not associated with delayed recall.
Conclusions:
Episodic memory was associated with prefrontal structures, and MTL and prefrontal structures did not predict memory decline. There was relative stability in memory over time. Findings suggest that episodic memory is more related to frontal structures, rather than encroaching AD pathology, in middle-aged PWH. Additional research should clarify if recognition is useful clinically to differentiate aMCI and HAND.
The dominant helminths infecting spiny mice (Acomys dimidiatus) in the montane wadis of the Sinai Peninsula of Egypt are spirurid nematodes, notably Protospirura muricola and Mastophorus muris. Both are relatively large robust stomach worms that accumulate in hosts resulting in high worm burdens. To ascertain whether the presence of spirurid worms or their burdens alters the host's likelihood of infection with other helminth species, we analysed a database containing quantitative data on helminth parasites of these mice (n = 431). This comprised of worm burdens recorded during 4 surveys, conducted at 4-year intervals, in 4 wadis, during late summer of each year. The presence of spirurid worms did not significantly alter species richness with other helminth species nor the likelihood of mice carrying other nematode species. However, there was a significant association, particularly of P. muricola, with the presence of intestinal stages of cestodes, and with the acanthocephalan Moniliformis acomysi. After controlling for intrinsic and extrinsic factors, mice harbouring spirurid worms had greater worm burdens of other helminths compared with mice without spirurids. Moreover, spirurid worm burdens showed a significant positive covariation with similarly adjusted species richness of other helminths, non-spirurid helminths, non-spirurid nematodes, oxyuroid nematodes and intestinal stage cestode worm burdens. We interpret these results as an indication that the key driver for co-occurrence of spirurids with other helminths is likely to be transmission via common arthropod hosts (for cestodes and acanthocephalans), but also that mice carrying the heavier spirurid worm burdens become more susceptible to directly transmitted nematodes such as the Oxyuroidea.
Addressing mental and physical health problems and promoting wellbeing in educational settings is a global priority. Teachers present a high risk of stress and burnout, which negatively impacts their professional performance as well as their mental and physical health. Compassion-based interventions have been found effective in promoting psychosocial and physiological wellbeing.
Objectives
The current paper presents preliminary findings of the impact of a 6-module Compassionate Mind Training intervention for Teachers (CMT-T) on immunological markers and the Conserved Transcriptional Response to Adversity (CTRA; a gene expression signature that involves a group of 53 genes: pro-inflammatory genes, type I interferon response and genes related to antibody synthesis).
Methods
A pilot non-controlled study was conducted in a sample of public-school teachers in Portugal (n=36). Participants were assessed at 4 time-points: 1) Extended Baseline Control_M0, in order to establish a within-subjects psychological and biophysiological baseline (8 weeks before the start of the CMT-T); 2) Pre-intervention_M1 (8-weeks after M0); 3) Post-intervention_M2 (8-weeks after M1); and 4) Follow-up_M3 (3 months after the CMT-T end). In all assessment moments, participants completed a set of psychological self-report measures and were assessed in immunological and epigenetic biological markers through the collection of blood. After M1, teachers completed the 8-week group CMT-T intervention and given access to its resources and materials. They were instructed to practice daily and incorporate the teachings in their personal and professional lives. All assessments and the CMT-T intervention took place at the schools.
Results
Preliminary data on the impact of CMT-T on Immune Response Profiling revealed that teachers’ Natural Killer (i.e., NK) cells were decreased after the CMT-T intervention. In regard to the CTRA gene expression, results showed that type one interferon response genes (e.g., IFI16, IFI27L2, IFITM2, IFITM3, IFITM4P) were decreased after the intervention. In addition, we observed that the gene c-Jun, a pro-inflammatory gene, had a decreased expression after the CMT-T intervention.
Conclusions
These preliminary findings seem to corroborate previous studies involving the type one interferon response, the pro-inflammatory genes and antibody synthesis genes in a signature involving 53 genes previously described as the CTRA gene signature. Furthermore, our results suggest that cultivating compassion using a compassion focused intervention may have a positive impact on markers of the immune system response, associated with how our bodies respond to stress, infection and cancer, as well as, on reducing the expression of genes related to our bodies’ response to stress and inflammation.
Most evidence on suicidal thoughts, plans and attempts comes from Western countries; prevalence rates may differ in other parts of the world.
Aims
This study determined the prevalence of suicidal thoughts, plans and attempts in high school students in three different regional settings in Kenya.
Method
This was a cross-sectional study of 2652 high school students. We asked structured questions to determine the prevalence of various types of suicidality, the methods planned or effected, and participants’ gender, age and form (grade level). We provided descriptive statistics, testing significant differences by chi-squared and Fisher's exact tests, and used logistic regression to identify relationships among different variables and their associations with suicidality.
Results
The prevalence rates of suicidal thoughts, plans and attempts were 26.8, 14.9 and 15.7%, respectively. These rates are higher than those reported for Western countries. Some 6.7% of suicide attempts were not associated with plans. The most common method used in suicide attempts was drinking chemicals/poison (18.8%). Rates of suicidal thoughts and plans were higher for older students and students in urban rather than rural locations, and attempts were associated with female gender and higher grade level – especially the final year of high school, when exam performance affects future education and career prospects.
Conclusion
Suicidal thoughts, plans and attempts are prevalent in Kenyan high school students. There is a need for future studies to determine the different starting points to suicidal attempts, particularly for the significant number whose attempts are not preceded by thoughts and plans.
Helminth parasites were studied in the wood mouse, Apodemus sylvaticus, in southern England in September of each of four successive years (1994–1997). Nine species of helminths were recorded: five nematodes (Heligmosomoides polygyrus, Syphacia stroma, Pelodera strongyloides, Trichuris muris, Capillaria murissylvatici), two cestodes (Microsomacanthus crenata, Taenia taeniaeformis) and two trematodes (Corrigia vitta, Brachylaemus recurvum). In total, 134 mice were examined and 91.8% carried at least one species of helminth. The majority of mice carried two to three species (60.5%) and the highest combination was six of the nine species recorded in the study. The patterns of between-year variations in the prevalence and abundance of infection were different for each of the six species for which sufficient quantitative data were available to enable statistical analysis. For H. polygyrus, the most important source of variation arose from between-year differences, host age and the interaction of these factors: abundance increased with host age but in 1995 the age pattern was markedly different from that in the remaining years. The abundance of C. vitta also varied significantly between years but additionally there was a strong independent age effect. For M. crenata, the year × age interaction was significant, indicating that abundance among different age cohorts varied from year to year but there was also a weak significant main effect of age arising from the youngest age cohort carrying no parasites and the oldest age cohort the heaviest infections. For P. strongyloides the only significant factor was between-year variation with 1995 being a year of exceptionally low prevalence and abundance of infection. No significant between-year variation was detected for S. stroma but there was a strong sex effect (males carrying heavier infections) and an age effect (older mice of both sexes carrying heavier infections). The abundance of Trichuris muris varied only in relation to host age, worm burdens growing in intensity with increasing age, but there was also a significant interaction between year and host sex with respect to prevalence. For the remaining three species, the prevalence of infections was too low (< 8.2%) to enable any meaningful interpretation. This analysis emphasizes the need for carefully controlled statistical procedures in aiding the interpretation and the prioritization of the factors affecting worm burdens in wild rodents.
NASA’s all-sky survey mission, the Transiting Exoplanet Survey Satellite (TESS), is specifically engineered to detect exoplanets that transit bright stars. Thus far, TESS has successfully identified approximately 400 transiting exoplanets, in addition to roughly 6 000 candidate exoplanets pending confirmation. In this study, we present the results of our ongoing project, the Validation of Transiting Exoplanets using Statistical Tools (VaTEST). Our dedicated effort is focused on the confirmation and characterisation of new exoplanets through the application of statistical validation tools. Through a combination of ground-based telescope data, high-resolution imaging, and the utilisation of the statistical validation tool known as TRICERATOPS, we have successfully discovered eight potential super-Earths. These planets bear the designations: TOI-238b (1.61$^{+0.09} _{-0.10}$ R$_\oplus$), TOI-771b (1.42$^{+0.11} _{-0.09}$ R$_\oplus$), TOI-871b (1.66$^{+0.11} _{-0.11}$ R$_\oplus$), TOI-1467b (1.83$^{+0.16} _{-0.15}$ R$_\oplus$), TOI-1739b (1.69$^{+0.10} _{-0.08}$ R$_\oplus$), TOI-2068b (1.82$^{+0.16} _{-0.15}$ R$_\oplus$), TOI-4559b (1.42$^{+0.13} _{-0.11}$ R$_\oplus$), and TOI-5799b (1.62$^{+0.19} _{-0.13}$ R$_\oplus$). Among all these planets, six of them fall within the region known as ‘keystone planets’, which makes them particularly interesting for study. Based on the location of TOI-771b and TOI-4559b below the radius valley we characterised them as likely super-Earths, though radial velocity mass measurements for these planets will provide more details about their characterisation. It is noteworthy that planets within the size range investigated herein are absent from our own solar system, making their study crucial for gaining insights into the evolutionary stages between Earth and Neptune.
The COVID-19 pandemic in Australia has profoundly affected older adults, particularly in the state of Victoria, which experienced strict lockdown restrictions six times since the pandemic began in 2020; totalling 245 days over three years. This study explored the experiences of older adults living in retirement villages during the first three lockdowns in Victoria from March 2020 to February 2021. We draw on the concept of the ‘third age’ to explore how residents’ post-retirement social and lifestyle aspirations were disrupted by the pandemic and associated lockdowns. In-depth qualitative interviews were conducted with 14 residents during January and February 2021. All data were analysed using thematic mapping. Five key themes were identified: (1) benefits and frustrations of retirement village living during a pandemic; (2) the loss of amenities and activities; (3) heightened loneliness and social isolation; (4) reaching out to others; and (5) variable experiences of operators’ response. Although the COVID-19 pandemic has highlighted short-term and long-term issues around social isolation and the management of retirement villages, it has also demonstrated the resilience of residents and the strength of community ties and relationships. Retirement villages are promoted as age-friendly environments that enable an active and healthy post-retirement lifestyle. Yet our findings reveal heterogeneity within village populations. When services closed during lockdowns, this revealed a tension between the policy assumption that retirement villages are a housing consumption choice, and the unmet needs of those residents who depend on village services for day-to-day functioning.
Women infected during pregnancy with TORCH (Toxoplasmosis, Other, Rubella, Cytomegalovirus, and Herpes simplex viruses) pathogens have a higher risk of adverse birth outcomes including stillbirth / miscarriage because of mother-to-child transmission. To investigate these risks in pregnant women in Kenya, we analyzed serum specimens from a pregnancy cohort study at three healthcare facilities. A sample of 481 participants was selected for TORCH pathogen antibody testing to determine seroprevalence. A random selection of 285 from the 481 participants was selected to measure seroconversion. These sera were tested using an IgG enzyme-linked immunosorbent assay against 10 TORCH pathogens. We found that the seroprevalence of all but three of the 10 TORCH pathogens at enrollment was >30%, except for Bordetella pertussis (3.8%), Treponema pallidum (11.4%), and varicella zoster virus (0.5%). Conversely, very few participants seroconverted during their pregnancy and were herpes simplex virus type 2 (n = 24, 11.2%), parvovirus B19 (n = 14, 6.2%), and rubella (n = 12, 5.1%). For birth outcomes, 88% of the participant had live births and 12% had stillbirths or miscarriage. Cytomegalovirus positivity at enrolment had a statistically significant positive association with a live birth outcome (p = 0.0394). Of the 10 TORCH pathogens tested, none had an association with adverse pregnancy outcome.
Clay swelling, an important phenomenon in natural systems, can dramatically affect the properties of soils and sediments. Of particular interest in low-salinity, saturated systems are osmotic hydrates, forms of smectite in which the layer separation greatly exceeds the thickness of a single smectite layer due to the intercalation of water. In situ X-ray diffraction (XRD) studies have shown a strong link between ionic strength and average interlayer spacing in osmotic hydrates but also indicate the presence of structural disorder that has not been fully described. In the present study the structural state of expanded smectite in sodium chloride solutions was investigated by combining very low electron dose, high-resolution cryogenic-transmission electron microscopy observations with XRD experiments. Wyoming smectite (SWy-2) was embedded in vitreous ice to evaluate clay structure in aqua. Lattice-fringe images showed that smectite equilibrated in aqueous, low-ionic-strength solutions, exists as individual smectite layers, osmotic hydrates composed of parallel layers, as well as disordered layer conformations. No evidence was found here for edge-to-sheet attractions, but significant variability in interlayer spacing was observed. Whether this variation could be explained by a dependence of the magnitude of long-range cohesive (van der Waals) forces on the number of layers in a smectite particle was investigated here. Calculations of the Hamaker constant for layer-layer interactions showed that van der Waals forces may span at least five layers plus the intervening water and confirmed that forces vary with layer number. Drying of the disordered osmotic hydrates induced re-aggregation of the smectite to form particles that exhibited coherent scattering domains. Clay disaggregation and restacking may be considered as an example of oriented attachment, with the unusual distinction that it may be cycled repeatedly by changing solution conditions.
Among people with HIV (PWH), the apolipoprotein e4 (APOE-e4) allele, a genetic marker associated with Alzheimer’s disease (AD), and self-reported family history of dementia (FHD), considered a proxy for higher AD genetic risk, are independently associated with worse neurocognition. However, research has not addressed the potential additive effect of FHD and APOE-e4 on global and domain-specific neurocognition among PWH. Thus, the aim of the current investigation is to examine the associations between FHD, APOE-e4, and neurocognition among PWH.
Participants and Methods:
283 PWH (Mage=50.9; SDage=5.6) from the CNS HIV Anti-Retroviral Therapy Effects Research (CHARTER) study completed comprehensive neuropsychological and neuromedical evaluations and underwent APOE genotyping. APOE status was dichotomized into APOE-e4+ and APOE-e4-. APOE-e4+ status included heterozygous and homozygous carriers. Participants completed a free-response question capturing FHD of a first- or second-degree relative (i.e., biologic parent, sibling, children, grandparent, grandchild, uncle, aunt, nephew, niece, half-sibling). A dichotomized (yes/no), FHD variable was used in analyses. Neurocognition was measured using global and domain-specific demographically corrected (i.e., age, education, sex, race/ethnicity) T-scores. t-tests were used to compare global and domain-specific demographically-corrected T-scores by FHD status and APOE-e4 status. A 2x2 factorial analysis of variance (ANOVA) was used to model the interactive effects of FHD and APOE-e4 status. Tukey’s HSD test was used to follow-up on significant ANOVAs.
Results:
Results revealed significant differences by FHD status in executive functioning (t(281)=-2.3, p=0.03) and motor skills (t(278)=-2.0, p=0.03) such that FHD+ performed worse compared to FHD-. Differences in global neurocognition by FHD status approached significance (t(281)=-1.8, p=.069). Global and domain-specific neurocognitive performance were comparable among APOE-e4 carriers and noncarriers (ps>0.05). Results evaluating the interactive effects of FHD and APOE-e4 showed significant differences in motor skills (F(3)=2.7, p=0.04) between the FHD-/APOE-e4+ and FHD+/APOE-e4- groups such that the FHD+/APOE-e4- performed worse than the FHD-/APOE-e4+ group (p=0.02).
Conclusions:
PWH with FHD exhibited worse neurocognitive performance within the domains of executive functioning and motor skills, however, there were no significant differences in neurocognition between APOE-e4 carriers and noncarriers. Furthermore, global neurocognitive performance was comparable across FHD/APOE-e4 groups. Differences between the FHD-/APOE-e4+ and FHD+/APOE-e4- groups in motor skills were likely driven by FHD status, considering there were no independent effects of APOE-e4 status. This suggests that FHD may be a predispositional risk factor for poor neurocognitive performance among PWH. Considering FHD is easily captured through self-report, compared to blood based APOE-e4 status, PWH with FHD should be more closely monitored. Future research is warranted to address the potential additive effect of FHD and APOE-e4 on rates of global and domain-specific neurocognitive decline and impairment over time among in an older cohort of PWH, where APOE-e4 status may have stronger effects.