Cardiovascular changes during peanut-induced allergic reactions in human subjects.

BACKGROUND: Food allergy is the most common cause of anaphylaxis. Changes in posture during acute reactions can trigger fatal outcomes, but the impact of allergic reactions on the cardiovascular system in nonfatal reactions remains poorly understood. OBJECTIVE: Our aim was to systematically evaluate changes in cardiovascular function during acute allergic reactions to peanut. METHODS: Participants underwent double-blind placebo-controlled food challenge to peanut as part of a clinical trial. Changes in hemodynamic parameters (heart rate, stroke volume, blood pressure, and peripheral blood flow) and electrocardiogram findings during food challenges were assessed using noninvasive continuous monitoring. RESULTS: A total of 57 adults (median age 24 years [interquartile range = 20-29]), 53% of whom were female, participated; 22 (39%) had anaphylaxis. Acute reactions were associated with significant changes in stroke volume (mean decrease of 4.2% [95% CI = 0.8-7.6; P = .03]), heart rate (mean increase 11.6% [95% CI = 8.4-14.8; P < .0001]), and peripheral blood flow (mean increase 19.7% [95% CI = 10.8-28.6; P < .0001]), irrespective of reaction severity. These changes were reproduced at a subsequent repeat peanut challenge in 26 participants, and could be reversed with administration of intravenous fluids which resulted in faster resolution of abdominal symptoms. CONCLUSIONS: In this first detailed human study of cardiovascular changes during food-induced allergic reactions, we found evidence for significant fluid redistribution, independent of reaction severity. This provides a sound rationale for optimizing venous return during significant allergic reactions to food. Finally, these data provide a new paradigm for understanding severity in anaphylaxis, in which poor outcomes may occur as a result of a failure in compensatory mechanisms.

ATRX interacts with H3.3 in maintaining telomere structural integrity in pluripotent embryonic stem cells.

ATRX (alpha thalassemia/mental retardation syndrome X-linked) belongs to the SWI2/SNF2 family of chromatin remodeling proteins. Besides the ATPase/helicase domain at its C terminus, it contains a PHD-like zinc finger at the N terminus. Mutations in the ATRX gene are associated with X-linked mental retardation (XLMR) often accompanied by alpha thalassemia (ATRX syndrome). Although ATRX has been postulated to be a transcriptional regulator, its precise roles remain undefined. We demonstrate ATRX localization at the telomeres in interphase mouse embryonic stem (ES) cells in synchrony with the incorporation of H3.3 during telomere replication at S phase. Moreover, we found that chromobox homolog 5 (CBX5) (also known as heterochromatin protein 1 alpha, or HP1 alpha) is also present at the telomeres in ES cells. We show by coimmunoprecipitation that this localization is dependent on the association of ATRX with histone H3.3, and that mutating the K4 residue of H3.3 significantly diminishes ATRX and H3.3 interaction. RNAi-knockdown of ATRX induces a telomere-dysfunction phenotype and significantly reduces CBX5 enrichment at the telomeres. These findings suggest a novel function of ATRX, working in conjunction with H3.3 and CBX5, as a key regulator of ES-cell telomere chromatin.

Effect of false-positive screening mammograms on rescreening in Western Australia.

OBJECTIVES: To quantify the effect of previous false-positive mammogram results on rescreening rates in a population of women participating in the BreastScreen WA (BSWA) program. DESIGN AND PARTICIPANTS: Retrospective cohort study of women aged 50-69 years who received free screening mammograms at BSWA between 1 January 1995 and 31 December 2007. MAIN OUTCOME MEASURES: Percentages of women attending rescreening, and risk ratios for rescreening. RESULTS: A total of 22 396 screening mammograms were falsely reported as positive, and 560 333 mammogram screens were reported as normal (negative). Women with a false-positive index mammogram result were less likely than women with a true-negative index mammogram result to attend rescreening at 27 months (67.6% v 70.7%; risk ratio, 0.96; P < 0.001). A reduced rescreening rate was seen in all subgroups of women except Indigenous women. Rescreening rates were affected by the types of assessment done at the recall visit. CONCLUSION: Mammographic population screening services should keep their false-positive result rates low, to prevent women from being deterred from screening.

Characteristics of Patients with Chronic Obstructive Pulmonary Disease Treated with Long-Acting Bronchodilators in a Real-World Setting in Singapore: A Single-Center Observational Study.

Introduction: There is limited real-world evidence regarding clinical practice for chronic obstructive pulmonary disease (COPD) in Singapore. We compared baseline clinical characteristics and evaluated outcomes in patients with COPD who initiated treatment with either a long-acting muscarinic antagonist (LAMA) or a LAMA and a long-acting ß2-agonist (LAMA+LABA). Methods: This was a single-center observational study at Changi General Hospital, Singapore. Routine clinical data (hospital visits, case management, lung function, laboratory/imaging results, medication orders) were collected and compiled into a data warehouse. Eligible patients with COPD were ≥40 years old and newly prescribed LAMA or LAMA+LABA during the enrollment period. Patient characteristics in the baseline period (6 months) were compared between treatments. Clinical worsening was measured as a composite endpoint, defined as the first of a change in maintenance treatment class or a moderate-to-severe exacerbation during follow-up (12 months). Results: In total, 261 patients were included in the baseline period (LAMA: 73; LAMA+LABA: 188). In the baseline period, patients receiving LAMA+LABA versus LAMA had significantly lower body mass index, higher COPD Assessment Test score and worse lung function, and numerically higher exacerbation history. Prevalence of comorbidities was similar between treatment groups. In follow-up, high rates of clinical worsening were observed regardless of treatment regimen (LAMA: 38/73 [52%]; LAMA+LABA: 86/188 [46%]). Median time-to-clinical worsening was 340 days for the LAMA cohort and the raw median 154 days (interquartile range: 44-225) for the LAMA+LABA cohort. Median medication dispensation rate (0.86; interquartile range: 0.56-1.00) was similar between treatments. Conclusion: Patients initiating treatment with LAMA+LABA had more severe COPD than patients prescribed LAMA. The proportion of patients experiencing clinical worsening was similarly high in both cohorts, suggesting that early identification and treatment optimization are necessary.

Paired sensitivity analysis of four SARS-CoV-2 serological immunoassays in a longitudinal cohort of convalescent hospital staff.

BACKGROUND: SARS-CoV-2 serological testing has seen extensive academic and clinical use from investigating correlates of immunity to seroprevalence, convalescent plasma and vaccine trials. Interpretation of these studies will depend on robust validation of the longitudinal sensitivities of these assays, especially in the context of mild disease which makes up the majority of the Coronavirus Disease 2019 (COVID-19) caseload. METHODS: Hospital staff (n = 94) returning to work following polymerase chain reaction confirmed COVID-19 were offered antibody testing to assist with laboratory verification. Initial specimens were collected at median 29 days post-symptom onset and run on the Roche, Abbott, Siemens and DiaSorin platforms. Re-sampling occurred at median 142 days from a subset of the initial cohort (n = 62) that had volunteered to provide further serum samples to assist in longitudinal sensitivity analysis. Samples that were not run across all four platforms were excluded from analysis. RESULTS: Comparative sensitivity analysis was conducted on 89/94 of the initial specimens and 55/62 of the repeat specimens. Sensitivity at initial sampling ranged from 78 to 87% across platforms. At re-sampling, sensitivities were: 100% (Roche), 45% (Abbott), 100% (Siemens), and 80% (DiaSorin). Paired analysis using the longitudinal cohort (n = 55) demonstrated stable or increasing median assay values on three platforms, with a clear reduction seen only on the Abbott platform (4.78 to 1.34) with corresponding sensitivity drop-off (81.8% to 45.4%). CONCLUSION: The Abbott assay demonstrated sensitivity drop-off and decrease in median assay signal below detection threshold at four to five months. This has implications on the interpretation and design of future studies.

Molecular analysis of the PArkin co-regulated gene and association with male infertility.

OBJECTIVE: To investigate the potential role of PArkin co-regulated gene (PACRG) in human male infertility. DESIGN: Case-control study. SETTING: Academic reproductive biology department. PATIENT(S): Blood samples were obtained from 610 patients and 156 normal control subjects. INTERVENTION(S): Genomic DNA was used as template for polymerase chain reaction amplification of the PACRG promoter and coding exons. The amplified fragments were tested for DNA sequence variations by direct sequencing and restriction enzyme analysis. MAIN OUTCOME MEASURE(S): Gene structure and sequence alterations of PACRG in infertile male patients. RESULT(S): The structure of PACRG was determined to comprise 5 coding exons, generating a single transcript in the testis which encoded a predicted protein of 257 amino acids. No pathogenic mutations were identified; however, a variant in the promoter of PACRG was shown to be significantly associated with azoospermia, but not oligospermia, in the case-control cohort. CONCLUSION(S): Mutation of PACRG was not identified as a cause of male infertility, but variation in the promoter was demonstrated to be a risk factor associated with azoospermia.

Histone H3.3 incorporation provides a unique and functionally essential telomeric chromatin in embryonic stem cells.

Little is known about the telomere chromatin dynamics of embryonic stem (ES) cell. Here, we demonstrate localization of histone H3.3 at interphase telomeres and enrichment of Ser31-phosphorylated H3.3 at metaphase telomeres in pluripotent mouse ES cells. Upon differentiation, telomeric H3.3S31P signal decreases, accompanied by increased association of heterochromatin repressive marks and decreased micrococcal nuclease sensitivity at the telomeres. H3.3 is recruited to the telomeres at late S/G2 phase, coinciding with telomere replication and processing. RNAi-depletion of H3.3 induces telomere-dysfunction phenotype, providing evidence for a role of H3.3 in the regulation of telomere chromatin integrity in ES cells. The distinctive changes in H3.3 distribution suggests the existence of a unique and functionally essential telomere chromatin in ES cells that undergoes dynamic differentiation-dependent remodeling during the process of differentiation.