The (p)ppGpp-mediated stringent response is important for bacterial survival in nutrient limiting conditions. For maximal effect, (p)ppGpp interacts with the cofactor DksA, which stabilizes ...(p)ppGpp's interaction with RNA polymerase. We previously demonstrated that (p)ppGpp was required for the virulence of Haemophilus ducreyi in humans. Here, we constructed an H. ducreyi dksA mutant and showed it was also partially attenuated for pustule formation in human volunteers. To understand the roles of (p)ppGpp and DksA in gene regulation in H. ducreyi, we defined genes potentially altered by (p)ppGpp and DksA deficiency using transcriptome sequencing (RNA-seq). In bacteria collected at stationary phase, lack of (p)ppGpp and DksA altered expression of 28% and 17% of H. ducreyi open reading frames, respectively, including genes involved in transcription, translation, and metabolism. There was significant overlap in genes differentially expressed in the (p)ppGpp mutant relative to the dksA mutant. Loss of (p)ppGpp or DksA resulted in the dysregulation of several known virulence determinants. Deletion of dksA downregulated lspB and rendered the organism less resistant to phagocytosis and increased its sensitivity to oxidative stress. Both mutants had reduced ability to attach to human foreskin fibroblasts; the defect correlated with reduced expression of the Flp adhesin proteins in the (p)ppGpp mutant but not in the dksA mutant, suggesting that DksA regulates the expression of an unknown cofactor(s) required for Flp-mediated adherence. We conclude that both (p)ppGpp and DksA serve as major regulators of H. ducreyi gene expression in stationary phase and have both overlapping and unique contributions to pathogenesis.
In an effort to expand the worldwide pool of available medical countermeasures (MCM) against radiation, the PEGylated G-CSF (PEG-G-CSF) molecules Neulasta and Maxy-G34, a novel PEG-G-CSF designed for ...increased half-life and enhanced activity compared to Neulasta, were examined in a murine model of the Hematopoietic Syndrome of the Acute Radiation Syndrome (H-ARS), along with the lead MCM for licensure and stockpiling, G-CSF. Both PEG-G-CSFs were shown to retain significant survival efficacy when administered as a single dose 24 h post-exposure, compared to the 16 daily doses of G-CSF required for survival efficacy. Furthermore, 0.1 mg kg of either PEG-G-CSF affected survival of lethally-irradiated mice that was similar to a 10-fold higher dose. The one dose/low dose administration schedules are attractive attributes of radiation MCM given the logistical challenges of medical care in a mass casualty event. Maxy-G34-treated mice that survived H-ARS were examined for residual bone marrow damage (RBMD) up to 9 mo post-exposure. Despite differences in Sca-1 expression and cell cycle position in some hematopoietic progenitor phenotypes, Maxy-G34-treated mice exhibited the same degree of hematopoietic stem cell (HSC) insufficiency as vehicle-treated H-ARS survivors in competitive transplantation assays of 150 purified Sca-1+cKit+lin-CD150+cells. These data suggest that Maxy-G34, at the dose, schedule, and time frame examined, did not mitigate RBMD but significantly increased survival from H-ARS at one-tenth the dose previously tested, providing strong support for advanced development of Maxy-G34, as well as Neulasta, as MCM against radiation.
The threat of radiation exposure from warfare or radiation accidents raises the need for appropriate animal models to study the acute and chronic effects of high dose rate radiation exposure. The ...goal of this study was to assess the late development of fibrosis in multiple organs (kidney, heart, and lung) in survivors of the C57BL/6 mouse model of the hematopoietic-acute radiation syndrome (H-ARS). Separate groups of mice for histological and functional studies were exposed to a single uniform total body dose between 8.53 and 8.72 Gy of gamma radiation from a Cs radiation source and studied 1-21 mo later. Blood urea nitrogen levels were elevated significantly in the irradiated mice at 9 and 21 mo (from ∼22 to 34 ± 3.8 and 69 ± 6.0 mg dL, p < 0.01 vs. non-irradiated controls) and correlated with glomerosclerosis (29 ± 1.8% vs. 64 ± 9.7% of total glomeruli, p < 0.01 vs. non-irradiated controls). Glomerular tubularization and hypertrophy and tubular atrophy were also observed at 21 mo post-total body irradiation (TBI). An increase in interstitial, perivascular, pericardial and peribronchial fibrosis/collagen deposition was observed from ∼9-21 mo post-TBI in kidney, heart, and lung of irradiated mice relative to age-matched controls. Echocardiography suggested decreased ventricular volumes with a compensatory increase in the left ventricular ejection fraction. The results indicate that significant delayed effects of acute radiation exposure occur in kidney, heart, and lung in survivors of the murine H-ARS TBI model, which mirrors pathology detected in larger species and humans at higher radiation doses focused on specific organs.
The identification of the optimal administration schedule for an effective medical countermeasure is critical for the effective treatment of individuals exposed to potentially lethal doses of ...radiation. The efficacy of filgrastim (Neupogen®), a potential medical countermeasure, to improve survival when initiated at 48 h following total body irradiation in a non-human primate model of the hematopoietic syndrome of the acute radiation syndrome was investigated. Animals were exposed to total body irradiation, antero-posterior exposure, total midline tissue dose of 7.5 Gy, (target lethal dose 50/60) delivered at 0.80 Gy min, using linear accelerator-derived 6 MV photons. All animals were administered medical management. Following irradiation on day 0, filgrastim (10 μg kg d) or the control (5% dextrose in water) was administered subcutaneously daily through effect (absolute neutrophil count ≥ 1,000 cells μL for three consecutive days). The study (n = 80) was powered to demonstrate a 25% improvement in survival following the administration of filgrastim or control beginning at 48 ± 4 h post-irradiation. Survival analysis was conducted on the intention-to-treat population using a two-tailed null hypothesis at a 5% significance level. Filgrastim, initiated 48 h after irradiation, did not improve survival (2.5% increase, p = 0.8230). These data demonstrate that efficacy of a countermeasure to mitigate lethality in the hematopoietic syndrome of the acute radiation syndrome can be dependent on the interval between irradiation and administration of the medical countermeasure.
There is limited understanding of the pre-exposure prophylaxis (PrEP) care continuum specific to Latino/x gay, bisexual, and other sexual minority men (SMM) that encompasses the population residing ...outside of large metropolitan or urban areas.
We examined trends and characteristics associated with the PrEP care continuum with data from the 2014-2020 cycles of the American Men's Internet Survey, an annual online cross-sectional behavioral survey of cisgender SMM in the United States.
We calculated PrEP continuum outcomes overall and by year among Hispanic/Latino SMM (n = 9010). We used generalized estimating equations with Poisson links to examine (1) temporal trends (2014-2020) in each step of the PrEP continuum and PrEP use in the past year stratified by PrEP eligibility and (2) correlates of each step of the PrEP continuum in 2020 using multivariable models.
Among 2283 Latino SMM in 2020, 84% reported PrEP awareness, 30% discussed PrEP with a provider, 15% used PrEP in the past year, and 12% were currently using PrEP. PrEP awareness increased from 52% in 2014 to 84% in 2020; and PrEP use in the past year increased from 4% in 2014 to 15% in 2020. In the multivariable models, age and PrEP eligibility were associated with PrEP use in the past year, and urban-rural classification was associated with current PrEP use.
While most of the Latino SMM are aware of PrEP, significant gaps remain in this population in discussing PrEP with a provider and using PrEP that require tailored strategies to enhance access to HIV prevention services.
BACKGROUNDSexual transmission rates of Chlamydia trachomatis (Ct) cannot be measured directly; however, the study of concordance of Ct infection in sexual partnerships (dyads) can help to illuminate ...factors influencing Ct transmission.
METHODSHeterosexual men and women with Ct infection and their sex partners were enrolled and partner-specific coital and behavioral data collected for the prior 30 days. Microbiological data included Ct culture, and nucleic acid amplification testing (NAAT), quantitative Ct polymerase chain reaction, and ompA genotyping. We measured Ct concordance in dyads and factors (correlates) associated with concordance.
RESULTSOne hundred twenty-one women and 125 men formed 128 dyads. Overall, 72.9% of male partners of NAAT-positive women and 68.6% of female partners of NAAT-positive men were Ct-infected. Concordance was more common in dyads with culture-positive members (78.6% of male partners, 77% of female partners). Partners of women and men who were NAAT-positive only had lower concordance (33.3%, 46.4%, respectively). Women in concordant dyads had significantly higher median endocervical quantitative Ct polymerase chain reaction values (3,032) compared with CT-infected women in discordant dyads (1013 inclusion forming units DNA equivalents per mL; P < 0.01). Among 54 Ct-concordant dyads with ompA genotype data for both members, 96.2% had identical genotypes.
CONCLUSIONSHigher organism load appears associated with concordance among women. Same-genotype chlamydial concordance was high in sexual partnerships. No behavioral factors were sufficiently discriminating to guide partner services activities. Findings may help model coitus-specific transmission probabilities.
This study sought to describe condom use over time in new and established adolescent relationships.
The outcome variable was time (in days) until first unprotected coital event. Analyses involved ...comparisons of Kaplan-Meier survival curves and Cox proportional hazards models.
Survival functions for the 2 relationship groups were significantly different. However, by 21 days the curves had converged: 43% of new and 41% of established relationships involved no unprotected coital events. Time to first unprotected coital event was significantly longer in new than in established relationships.
Prolongation of condom use in ongoing relationships may be a useful intervention to prevent sexually transmitted diseases.
Full text
Available for:
CEKLJ, FSPLJ, ODKLJ, UL, VSZLJ
We assessed differences in chlamydia screening rates according to race/ethnicity, insurance status, age, and previous sexually transmitted infection (STI) or pregnancy.
A retrospective cohort study ...was performed using electronic medical record and billing data for women 14 to 25 years of age in 2002-2007, assessing differences in the odds of a chlamydia test being performed at that visit.
Adjusted odds of a chlamydia test being performed were lower among women 14 to 15 years of age (odds ratio: 0.83 95% confidence interval: 0.70-1.00) and 20 to 25 years of age (20-21 years, odds ratio: 0.78 95% confidence interval: 0.70-0.89; 22-23 years, odds ratio: 0.76 95% confidence interval: 0.67-0.87; 24-25 years, odds ratio: 0.64 95% confidence interval: 0.57-0.73), compared with women 18 to 19 years of age. Black women had 3 times increased odds (odds ratio: 2.96 95% confidence interval: 2.66-3.28) and Hispanic women nearly 13 times increased odds (odds ratio: 12.89 95% confidence interval: 10.85-15.30) of testing, compared with white women. Women with public (odds ratio: 1.74 95% confidence interval: 1.58-1.91) and public pending (odds ratio: 6.85 95% confidence interval: 5.13-9.15) insurance had increased odds of testing, compared with women with private insurance. After first STI diagnosis, differences according to race/ethnicity persisted but were smaller; after first pregnancy, differences persisted.
Despite recommendations to screen all sexually active young women for chlamydia, providers screened women differently according to age, race/ethnicity, and insurance status, although differences were reduced after first STI or pregnancy.
PDF
