Social Disparities among Sudden Death victims with HIV.

Although cardiovascular death is a growing source of mortality for people living with human immunodeficiency virus (HIV), the risk factors and circumstances surrounding sudden death in this population are poorly understood. We compared 399 adult sudden death victims reported by Emergency Medical Services in North Carolina to 1,114 controls. Sudden death was more common among HIV-positive than HIV-negative individuals (OR: 2.59, 95% CI: 1.15-5.83). In a multivariable model of sudden death victims including Black race, BMI, and history of divorce, incarceration, substance abuse, and respiratory disease, HIV-positive individuals were more likely to be Black (adjusted OR [aOR]: 6.04, 95% CI: 1.08-33.7) or divorced (aOR: 4.71, 95% CI: 1.04-21.3), adjusted for all other variables in the model. Compared to controls with HIV, sudden death victims with HIV were more likely to have a history of incarceration, divorce, respiratory disease, alcohol abuse, or dyslipidemia. A qualitative assessment of victims suggested that many died in isolation, suffering from past and current substance abuse and depression. HIV infection appears to be an important risk factor for sudden death, and incarceration history, social isolation, and medical comorbidities contribute to sudden death risk for HIV-positive individuals.

Symptoms prior to sudden death.

BACKGROUND: Sudden death accounts for up to 15% of all deaths among working age adults. A better understanding of victims' medical care and symptoms reported at their last medical encounter may identify opportunities for interventions to prevent sudden deaths. METHODS: From 2013-15, all out-of-hospital deaths, ages 18-64 reported by Emergency Medical Services (EMS) in Wake County, North Carolina were screened and adjudicated to identify 399 victims of sudden death, 264 of whom had available medical records. Demographic and clinical characteristics and prescribed medications were compared between victims with versus without a medical encounter within one month preceding death with chi-square tests and t-tests, as appropriate. Symptoms reported in medical encounters within one month preceding death were analyzed. RESULTS: Among the 264 victims with available medical records, 73 (27.7%) had at least one encounter within a month preceding death. These victims were older and more likely to have multiple chronic illnesses, yet most were not prescribed evidence-based medicines. Of these 73 victims, 30 (41.1%) reported cardiac symptoms including dyspnea, edema, and chest pain. CONCLUSIONS: Many victims seek medical care and report cardiac symptoms in the month prior to sudden death. However, medications that might prevent sudden death are under prescribed. These findings suggest that there are opportunities for intervention to prevent sudden death.

Variations in blood pressure control by medical comorbidities prior to sudden death.

Patients with hypertension have increased risk of sudden death, but the impact of blood pressure control in sudden death is not clear. To better understand potential opportunities to prevent sudden, we assessed blood pressure control, comorbidities, and the number of recent medical encounters among all-cause sudden death victims. Less than 40% of sudden death victims with hypertension had controlled blood pressure prior to death. Furthermore, increased frequency of medical visits and number of comorbidities were associated with better blood pressure control Strategies to address clinical inertia in hypertension treatment particularly for patients with fewer comorbidities may attenuate the risk of sudden death.

Requirement of essential Pbp2x and GpsB for septal ring closure in Streptococcus pneumoniae D39.

Bacterial cell shapes are manifestations of programs carried out by multi-protein machines that synthesize and remodel the resilient peptidoglycan (PG) mesh and other polymers surrounding cells. GpsB protein is conserved in low-GC Gram-positive bacteria and is not essential in rod-shaped Bacillus subtilis, where it plays a role in shuttling penicillin-binding proteins (PBPs) between septal and side-wall sites of PG synthesis. In contrast, we report here that GpsB is essential in ellipsoid-shaped, ovococcal Streptococcus pneumoniae (pneumococcus), and depletion of GpsB leads to formation of elongated, enlarged cells containing unsegregated nucleoids and multiple, unconstricted rings of fluorescent-vancomycin staining, and eventual lysis. These phenotypes are similar to those caused by selective inhibition of Pbp2x by methicillin that prevents septal PG synthesis. Dual-protein 2D and 3D-SIM (structured illumination) immunofluorescence microscopy (IFM) showed that GpsB and FtsZ have overlapping, but not identical, patterns of localization during cell division and that multiple, unconstricted rings of division proteins FtsZ, Pbp2x, Pbp1a and MreC are in elongated cells depleted of GpsB. These patterns suggest that GpsB, like Pbp2x, mediates septal ring closure. This first dual-protein 3D-SIM IFM analysis also revealed separate positioning of Pbp2x and Pbp1a in constricting septa, consistent with two separable PG synthesis machines.

Dynamic distribution of the SecA and SecY translocase subunits and septal localization of the HtrA surface chaperone/protease during Streptococcus pneumoniae D39 cell division.

UNLABELLED: The Sec translocase pathway is the major route for protein transport across and into the cytoplasmic membrane of bacteria. Previous studies reported that the SecA translocase ATP-binding subunit and the cell surface HtrA protease/chaperone formed a single microdomain, termed "ExPortal," in some species of ellipsoidal (ovococcus) Gram-positive bacteria, including Streptococcus pyogenes. To investigate the generality of microdomain formation, we determined the distribution of SecA and SecY by immunofluorescent microscopy in Streptococcus pneumoniae (pneumococcus), which is an ovococcus species evolutionarily distant from S. pyogenes. In the majority (≥ 75%) of exponentially growing cells, S. pneumoniae SecA (SecA (Spn)) and SecY (Spn) located dynamically in cells at different stages of division. In early divisional cells, both Sec subunits concentrated at equators, which are future sites of constriction. Further along in division, SecA(Spn) and SecY(Spn) remained localized at mid-cell septa. In late divisional cells, both Sec subunits were hemispherically distributed in the regions between septa and the future equators of dividing cells. In contrast, the HtrA (Spn) homologue localized to the equators and septa of most (> 90%) dividing cells, whereas the SrtA(Spn) sortase located over the surface of cells in no discernable pattern. This dynamic pattern of Sec distribution was not perturbed by the absence of flotillin family proteins, but was largely absent in most cells in early stationary phase and in cls mutants lacking cardiolipin synthase. These results do not support the existence of an ExPortal microdomain in S. pneumoniae. Instead, the localization of the pneumococcal Sec translocase depends on the stage of cell division and anionic phospholipid content. IMPORTANCE: Two patterns of Sec translocase distribution, an ExPortal microdomain in certain ovococcus-shaped species like Streptococcus pyogenes and a spiral pattern in rod-shaped species like Bacillus subtilis, have been reported for Gram-positive bacteria. This study provides evidence for a third pattern of Sec localization in the ovococcus human pathogen Streptococcus pneumoniae. The SecA motor and SecY channel subunits of the Sec translocase localize dynamically to different places in the mid-cell region during the division cycle of exponentially growing, but not stationary-phase, S. pneumoniae. Unexpectedly, the S. pneumoniae HtrA (HtrA(Spn)) protease/chaperone principally localizes to cell equators and division septa. The coincident localization of SecA(Spn), SecY (Spn), and HtrA (Spn) to regions of peptidoglycan (PG) biosynthesis in unstressed, growing cells suggests that the pneumococcal Sec translocase directs assembly of the PG biosynthesis apparatus to regions where it is needed during division and that HtrA(Spn) may play a general role in quality control of proteins exported by the Sec translocase.

Localization and cellular amounts of the WalRKJ (VicRKX) two-component regulatory system proteins in serotype 2 Streptococcus pneumoniae.

The WalRK two-component regulatory system coordinates gene expression that maintains cell wall homeostasis and responds to antibiotic stress in low-GC Gram-positive bacteria. Phosphorylated WalR (VicR) of the major human respiratory pathogen Streptococcus pneumoniae (WalR(Spn)) positively regulates transcription of several surface virulence genes and, most critically, pcsB, which encodes an essential cell division protein. Despite numerous studies of several species, little is known about the signals sensed by the WalK histidine kinase or the function of the WalJ ancillary protein encoded in the walRK(Spn) operon. To better understand the functions of the WalRKJ(Spn) proteins in S. pneumoniae, we performed experiments to determine their cellular localization and amounts. In contrast to WalK from Bacillus subtilis (WalK(Bsu)), which is localized at division septa, immunofluorescence microscopy showed that WalK(Spn) is distributed throughout the cell periphery. WalJ(Spn) is also localized to the cell surface periphery, whereas WalR(Spn) was found to be localized in the cytoplasm around the nucleoid. In fractionation experiments, WalR(Spn) was recovered from the cytoplasmic fraction, while WalK(Spn) and the majority of WalJ(Spn) were recovered from the cell membrane fraction. This fractionation is consistent with the localization patterns observed. Lastly, we determined the cellular amounts of WalRKJ(Spn) by quantitative Western blotting. The WalR(Spn) response regulator is relatively abundant and present at levels of approximately 6,200 monomers per cell, which are approximately 14-fold greater than the amount of the WalK(Spn) histidine kinase, which is present at approximately 460 dimers (920 monomers) per cell. We detected approximately 1,200 monomers per cell of WalJ(Spn) ancillary protein, similar to the amount of WalK(Spn).