ZO-1 Stabilizes the Tight Junction Solute Barrier through Coupling to the Perijunctional Cytoskeleton

ZO-1 binds numerous transmembrane and cytoplasmic proteins and is required for assembly of both adherens and tight junctions, but its role in defining barrier properties of an established tight junction is unknown. We depleted ZO-1 in MDCK cells using siRNA methods and observed specific defects in the barrier for large solutes, even though flux through the small claudin pores was unaffected. This permeability increase was accompanied by morphological alterations and reorganization of apical actin and myosin. The permeability defect, and to a lesser extent morphological changes, could be rescued by reexpression of either full-length ZO-1 or an N-terminal construct containing the PDZ, SH3, and GUK domains. ZO-2 knockdown did not replicate either the permeability or morphological phenotypes seen in the ZO-1 knockdown, suggesting that ZO-1 and -2 are not functionally redundant for these functions. Wild-type and knockdown MDCK cells had differing physiological and morphological responses to pharmacologic interventions targeting myosin activity. Use of the ROCK inhibitor Y27632 or myosin inhibitor blebbistatin increased TER in wild-type cells, whereas ZO-1 knockdown monolayers were either unaffected or changed in the opposite direction; paracellular flux and myosin localization were also differentially affected. These studies are the first direct evidence that ZO-1 limits solute permeability in established tight junctions, perhaps by forming a stabilizing link between the barrier and perijunctional actomyosin

The evolving SARS-CoV-2 epidemic in Africa: Insights from rapidly expanding genomic surveillance

INTRODUCTION Investment in Africa over the past year with regard to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) sequencing has led to a massive increase in the number of sequences, which, to date, exceeds 100,000 sequences generated to track the pandemic on the continent. These sequences have profoundly affected how public health officials in Africa have navigated the COVID-19 pandemic. RATIONALE We demonstrate how the first 100,000 SARS-CoV-2 sequences from Africa have helped monitor the epidemic on the continent, how genomic surveillance expanded over the course of the pandemic, and how we adapted our sequencing methods to deal with an evolving virus. Finally, we also examine how viral lineages have spread across the continent in a phylogeographic framework to gain insights into the underlying temporal and spatial transmission dynamics for several variants of concern (VOCs). RESULTS Our results indicate that the number of countries in Africa that can sequence the virus within their own borders is growing and that this is coupled with a shorter turnaround time from the time of sampling to sequence submission. Ongoing evolution necessitated the continual updating of primer sets, and, as a result, eight primer sets were designed in tandem with viral evolution and used to ensure effective sequencing of the virus. The pandemic unfolded through multiple waves of infection that were each driven by distinct genetic lineages, with B.1-like ancestral strains associated with the first pandemic wave of infections in 2020. Successive waves on the continent were fueled by different VOCs, with Alpha and Beta cocirculating in distinct spatial patterns during the second wave and Delta and Omicron affecting the whole continent during the third and fourth waves, respectively. Phylogeographic reconstruction points toward distinct differences in viral importation and exportation patterns associated with the Alpha, Beta, Delta, and Omicron variants and subvariants, when considering both Africa versus the rest of the world and viral dissemination within the continent. Our epidemiological and phylogenetic inferences therefore underscore the heterogeneous nature of the pandemic on the continent and highlight key insights and challenges, for instance, recognizing the limitations of low testing proportions. We also highlight the early warning capacity that genomic surveillance in Africa has had for the rest of the world with the detection of new lineages and variants, the most recent being the characterization of various Omicron subvariants. CONCLUSION Sustained investment for diagnostics and genomic surveillance in Africa is needed as the virus continues to evolve. This is important not only to help combat SARS-CoV-2 on the continent but also because it can be used as a platform to help address the many emerging and reemerging infectious disease threats in Africa. In particular, capacity building for local sequencing within countries or within the continent should be prioritized because this is generally associated with shorter turnaround times, providing the most benefit to local public health authorities tasked with pandemic response and mitigation and allowing for the fastest reaction to localized outbreaks. These investments are crucial for pandemic preparedness and response and will serve the health of the continent well into the 21st century

The relationship between levels of self-esteem, health locus of control and reported compliance with therapeutic regimens in patients with essential hypertension

Includes bibliographical references.The purpose of this study was to investigate the relationships between the level of self-esteem, health locus of control and reported compliance with therapeutic regimens in patients with essential hypertension. Five hypotheses were formulated to study this relationship: 1. There will be a significant positive relationship between level of self-esteem and extent of compliance with therapeutic regimen. 2. There will be a significant positive relationship between Internal Health Locus of Control (IHLC) and extent of compliance with therapeutic regimen. 3. There will be a significant negative relationship between Powerful Others' Health Locus of Control and the extent of compliance with therapeutic regimen. 4. There will be a significant negative relationship between Chance Health Locus of Control and the extent of compliance with therapeutic regimen. 5. Self-esteem will be positively correlated with IHLC. This study was conducted at two separate public health departments in the Midwest. One health department population was mainly rural while the other was suburban. Fifty participants, 25 from each health department, contributed data for the study. Of the 50, 20 were male and 30 were female. Their ages ranged from 40 to 91 with a mean age of 65.9 years. Criteria for participation included: (1) documentation of essential hypertension by health department personnel, (2) involvement in health department for less than two years, (3) documentation of three elevated blood pressure readings in the past year, (4) supervision by medical personnel for management of hypertension, and (5) self-administration of at least one medication for blood pressure control. Individuals meeting the study criteria were approached by the investigator, who explained the purpose of the study and elicited participation. Upon giving written consent, the participants were interviewed regarding their current therapeutic regimen as ordered by their physicians. They were then asked to complete two questionnaires. One was the Coopersmith Self-Esteem Inventory and the other the Wallstons' Multidimensional Health Locus of Control. The means and standard deviations for each group of measures were calculated. Pearson product-moment correlation coefficients were computed between the following: (1) self-esteem scores and health locus of control scores, (2) self-esteem scores and compliance scores, and (3) health locus of control scores and compliance scores. No statistically significant correlations were revealed between compliance and any of the selected variables: Sixty percent of the total population were compliant, with 27% of the compliant population possessing high self-esteem. Forty percent of the compliant sample were internally-oriented compared to 30% of the non-compliant group. Correlation of age with self-esteem or compliance also revealed no significant relationship. The results of this study indicated that the target population did not fit into the relationship pattern described in the literature between self-esteem and compliance with therapeutic regimens. There was a trend toward internally-oriented subjects being more compliant with their therapeutic regimens than externally-oriented subjects, but the level of the relationship did not reach statistical significance. It is suggested that in future studies more objective measures for compliance be employed and other personal and social factors related to compliance be identified.M.S. (Master of Science