Estimation of the infection attack rate of mumps in an outbreak among college students using paired serology

Mumps virus is a highly transmissible pathogen that is effectively controlled in countries with high vaccination coverage. Nevertheless, outbreaks have occurred worldwide over the past decades in vaccinated populations. Here we analyse an outbreak of mumps virus genotype G among college students in the Netherlands over the period 2009-2012 using paired serological data. To identify infections in the presence of preexisting antibodies we compared mumps specific serum IgG concentrations in two consecutive samples (n=746), whereby the first sample was taken when students started their study prior to the outbreaks, and the second sample was taken 2-5 years later. We fit a binary mixture model to the data. The two mixing distributions represent uninfected and infected classes. Throughout we assume that the infection probability increases with the ratio of antibody concentrations of the second to first sample. The estimated infection attack rate in this study is higher than reported earlier (0.095 versus 0.042). The analyses yield probabilistic classifications of participants, which are mostly quite precise owing to the high intraclass correlation of samples in uninfected participants (0.85, 95%CrI: 0.82-0.87). The estimated probability of infection increases with decreasing antibody concentration in the pre-outbreak sample, such that the probability of infection is 0.12 (95%CrI: 0.10-0.13) for the lowest quartile of the pre-outbreak samples and 0.056 (95%CrI: 0.044-0.068) for the highest quartile. We discuss the implications of these insights for the design of booster vaccination strategies.

Comparative effectiveness of sacubitril/valsartan versus angiotensin converting enzyme inhibitors/angiotensin receptor blockers in de novo heart failure patients

Introduction

Effective use of pharmacological therapy in de novo heart failure (HF) patients is key for slowing down the progression of HF. Randomised clinical trials have shown sacubitril/valsartan (sac/val), providing superior benefit over renin angiotensin system (RAS) blockade with angiotensin converting enzyme inhibitors (ACEi) in patients with HF with reduced ejection fraction (HFrEF) including de novo HF patients. However, real world evidence is scarce.

Purpose

To compare the rate of all-cause hospitalisations in a real world de novo HFrEF US patient population after initiating sac/val or initiating or continuing RAS blockade with ACEi or angiotensin receptor blockers (ARB) within one year of index date.

Methods

This retrospective, non-interventional cohort study included adult de novo HFrEF patients (left ventricular ejection fraction ≤40%), from the Optum Electronic Health Records, from Jan 2016 to Mar 2020 (study period: Dec 2013–Mar 2021) who were prescribed sac/val or ACEi/ARB within 30 days of a new HF diagnosis. Patients either with any history of HF in the prior two years or with prior sac/val treatment were excluded. Index date was defined as the first prescription of sac/val or ACEi/ARB after a new HF diagnosis (≤30 days prior to index). One-to-two greedy propensity score matching was used to balance the study arms on demographics and clinical covariates (medications, LVEF, selected comorbidities). Negative binomial models were used to compare the primary endpoint between treatment groups and across subgroups of interest. The primary endpoint was the rate of all-cause hospitalisations within one year from index. Treatment groups were stratified by age, sex, race, ethnicity, history of myocardial infarction, comorbidities and prior ACEi/ARB treatment. Statistical analyses were conducted using R and SAS software.

Results

Prior to matching, 3,290 patients were initiated on sac/val, 47,678 on ACEi/ARB and post-matching there were 3,290 patients on sac/val and 6,580 patients on ACEi/ARB. Patients with prior ACEi/ARB treatment in both the groups were 1,597 and 2,806, respectively. Mean age was 63.5 in sac/val and 63.7 years in ACEi/ARB groups. After propensity-score matching, the annual rate (per person-year) of all-cause hospitalisation was lower in sac/val compared with ACEi/ARB group, with incidence rate ratio (IRR) of 0.81 (95% confidence interval [CI]: 0.74–0.90) ≤1 year from index. Similarly, in the ACEi/ARB treatment naïve subgroup, sac/val treatment led to 20% reduction in the primary endpoint (IRR: 0.80, 95% CI: 0.69–0.92) compared with ACEi/ARB. Amongst subgroups, results were consistent for most, with significant reduction seen in all-cause hospitalisation rates with sac/val treatment vs. ACEi/ARB.

Conclusion

Treatment with sac/val vs. ACEi or ARB significantly reduced the risk of all-cause hospitalisations in this real-world study supporting the first-line use of sac/val in treating de novo HFrEF patients.

Funding Acknowledgement

Type of funding sources: Private company. Main funding source(s): Novartis Pharma AG

The Impact of Timing of Pertussis Vaccination During Pregnancy on Infant Antibody Levels at Birth: A Multi-Country Analysis

Background

Pertussis vaccination during pregnancy is an effective strategy at reducing pertussis-related morbidity and mortality in infancy and is recommended across several countries. However, the optimal timepoint for vaccination in pregnancy to afford maximal protection to newborns is yet to be elucidated. This multi-country analysis aimed to model the impact of timing of vaccination during pregnancy on infant antibody titers at birth.

Methods

A multi-country analysis on a cohort of mother-infant pairs (n=698) vaccinated between 19.6-37.1 weeks gestation was conducted. Data taken from four parent studies on pertussis vaccination during pregnancy were modelled using natural cubic splines and linear mixed models to study the association of both gestational age at vaccination and the interval between vaccination and delivery with pertussis-specific cord blood antibody levels after pertussis vaccination during pregnancy.

Results

Term born infants on average achieve the highest antibody levels at birth if women are vaccinated before 31 weeks’ gestation. When considering both term and preterm deliveries, an interval of at least 7.5 weeks between vaccination and delivery is required to achieve the highest cord blood antibody levels. The models show that vaccinating earlier than these timeframes will also provide the infant with equally high antibody levels at birth.

Conclusions

Vaccinating in the second and early third trimester results in the highest antibody levels at birth. Vaccinating earlier within this window is needed to provide equal benefits to both term and preterm born infants.

Transport of exogenous organic substances by invertebrate integuments: the field revisited

The notion that some marine invertebrates can use integumental uptake of organic compounds as a nutritional supplement dates back to the late 19th and early 20th centuries. This article provides a brief overview of more than a century's research, as it relates to significant stages in the development of experimental methods and concepts of general physiology. Emphasis is placed on changing paradigms and on the interplay between this specialized field of investigation and the mainstream of physiological thought. The present status of the field is summarized. The general consensus is challenged on the basis of previously published and new data from the author's laboratory. Particular emphasis is placed on data pointing toward an ultra-rapid turnover of amino acids in part of the epidermal space of the polychaete worm Nereis diversicolor. It is suggested that intra-epidermal L-alanine is compartmentalized metabolically or physically, and the consequences of this proposition are discussed in view of the general concepts of secondary active transport and intracellular isosmotic regulation. Future studies in this area of comparative physiology should concentrate not only on the molecular characteristics of the transporter proteins, but also on the way their function is integrated in the cellular physiology of the transporting cells. J. Exp. Zool. 289:254-265, 2001.

Integumentary L-histidine transport in a euryhaline polychaete worm: regulatory roles of calcium and cadmium in the transport event

Integumentary uptake of L-[(3)H]histidine by polychaete worms (Nereis succinea) from estuarine waters of Oahu, Hawaii was measured in the presence and absence of calcium and cadmium using a physiological saline that approximated the ion composition of 60 % sea water. In this medium 1 micromol L(−1) cadmium significantly increased (P<0.01) the uptake of 10 micromol L(−1)L-[(3)H]histidine, while 1 micromol L(−1) cadmium plus 25 micromol L(−1)L-leucine significantly decreased (P<0.01) amino acid uptake. L-[(3)H]histidine influx was a sigmoidal function (n=2. 21+/−0.16, mean +/− s.e.m.) of [L-histidine] (1?50 micromol L(−1)) in the absence of cadmium, but became a hyperbolic function with the addition of 1 micromol L(−1) cadmium. A decrease of calcium concentration from 6 to 0 mmol L(−1) (lithium substitution) significantly increased (P<0.01) amino acid influx in the presence and absence of cadmium. Calcium significantly reduced (P<0.01), and cadmium significantly increased (P<0.01), L-[(3)H]histidine influx J(max), without either divalent cation affecting amino acid influx K(t). Variation in external sodium concentration (0?250 mmol L(−1)) had no effect on 10 micromol L(−1)L-[(3)H]histidine influx, but amino acid entry was a sigmoidal function of both [cadmium] (n=2.34+/−0.44) and [lithium] (n=1.91+/−0.39) in the absence of calcium. A model is proposed for transapical L-[(3)H]histidine influx by a transporter that resembles the classical sodium-independent L-system carrier protein that is regulated by the external divalent cations calcium and cadmium.

Electrogenic, proton-coupled, intestinal dipeptide transport in herbivorous and carnivorous teleosts

In both herbivorous tilapia (Oreochromis mossambicus) and carnivorous rockfish (Sebastes caurinus) intestinal and pyloric cecal brush-border membrane vesicles (BBMV), [14C]glycylsarcosine ([14C]Gly-Sar) uptake was stimulated by a transmembrane proton gradient. A transmembrane K(+)-diffusion potential (inside negative) stimulated [14C]Gly-Sar uptake above that observed with short-circuited vesicles, whereas an inwardly directed Na+ gradient in both fishes had no effect on peptide uptake. In tilapia, [14C]Gly-Sar influx occurred by the combination of 1) a high-affinity, saturable, proton gradient-dependent carrier system [Kt [concentration that equals one-half of maximum influx (Jmax)] = 0.56 +/- 0.08 mM; Jmax = 1,945.0 +/- 174.6 pmol.mg protein-1.10 s-1]; 2) a low-affinity, nonsaturable (within 1-10 mM), proton gradient-dependent carrier system (nonsaturable carrier-mediated transport component = 4,514.0 +/- 28.1 pmol.mg protein-1.10 s-1.mM-1); and 3) a diffusional component accounting for < 10% of total influx within the concentration range tested. Influx (10 s) of 1-10 mM [14C]Gly-Sar in tilapia intestine was significantly (P < 0.01) inhibited by 10 mM diethylpyrocarbonate, a specific inhibitor of proton-coupled peptide transport systems. [14C]Gly-Sar influx into tilapia BBMV showed cis-inhibition and trans-stimulation by Gly-Pro, suggesting that [14C]Gly-Sar and Gly-Pro shared the same mucosal peptide transporter in fish. These observations strongly suggest that intestinal transport of peptides in herbivorous and carnivorous fishes is proton gradient dependent, electrogenic, sodium independent, and qualitatively resembles the peptide transport paradigm proposed for mammals.

Problems of interpreting integumental D-glucose fluxes by the integument of Schistosoma

1. The parasitic trematode Schistosoma mansoni can take up glucose across its surface at a rate three times higher than the glucose uptake by the mucosal border of the rabbit ileum. 2. Washout of tritiated polyethylene glycol (M Wt 4000) indicated that it was being lost through the integument and that the gut contribution is very small. 3. There is a peripheral diffusion resistance that will profoundly influence any transepidermal solute transfer.

Uniform ionophore A23187 distribution and cytoplasmic calcium buffering in intact human red cells

The divalent cation-selective ionophore A23187 has been used to characterize cytoplasmic Ca and Mg buffering, Ca2+-pump parameters and the properties of a Ca2+-activated K+-channel in intact red cells. A critical assumption in these studies has been that the ionophore causes a uniform increase in divalent cation-permeability in all the cells. This has now been tested directly in ATP-depleted human red cells by analysing the kinetics of ionophore-induced 45Ca-tracer and net Ca2+ fluxes. The experimental curves were all adequately fitted by single-exponentials at all ionophore concentrations tested. Moreover, statistical analysis of 61 individual tracer influx curves and of pooled data showed no trend towards fast second exponential components. These results demonstrate uniformity of ionophore distribution, ionophore-induced Ca2+-permeability, and cytoplasmic Ca-buffering among all the cells. Experiments involving mixing of cell suspensions with high and low original ionophore content, and involving ionophore extraction by albumin, demonstrate a rapid redistribution of ionophore among the cells, indicating that homogeneity of ionophoric effects is achieved through dynamic ionophore redistribution.

Recycling of D-glucose in collagenous cuticle: A means of nutrient conservation?

Transport by an epithelium, possessing an accumulating saturable transport system in the apical membrane as well as a finite Fick permeability to the transported solute, was considered in the steady state in the case of zero cis concentration, and in the presence of a peripheral diffusion resistance in a layer apposing the cis face of the tissue (unstirred solution or structural coating). Under suitable conditions, the combination of peripheral diffusion resistance and accumulating epithelium transport may lead to recycling of solute at the cis face of the epithelium. This causes a decrease of the effective permeability to diffusional trans-cis flow across the tissue. The phenomenon is discussed in terms of epidermal D-glucose transport by the integument of aquatic animals with a collagenous cuticle, such as the seawater-acclimated polychaete worm Nereis diversicolor. The recycling phenomenon may be of significance to other epithelia with the function of maintaining large concentration gradients of permeating substances.

D-Glucose transport across the apical membrane of the surface epithelium in Nereis diversicolor

Epidermal D-glucose transport was investigated in vivo in the brackish-water polychaete worm Nereis diversicolor. Transfer across the apical membrane is rate-limiting to D-glucose uptake, but the cuticle and/or mucus presents some resistance to D-glucose diffusion between bulk solution and transporting membrane. Maximal D-glucose influx is about 10(-12) mol sec-1 per cm2 of apical plasmalemma. Under natural conditions (approximately 1 microM D-glucose in the medium), backflux from the epidermal transport pool is negligible, but a significant paracellular outflux may occur. D-glucose influx across the apical membrane is Na+-dependent and completely inhibitable by phlorizin and harmaline; phloretin is less effective, and cytochalasin B has no effect. Influx is moderately depressed by KCN and iodoacetate, alpha-methyl-D-glucopyranoside is an effective substitute of D-glucose in transport. Animals acclimated to a low salinity, in which epidermal salt transport takes place, show a marked decrease of D-glucose transport capacity. On transfer of animals from a high to a low salinity, or vice versa, the corresponding change of influx occurs after a time-lag of at least an hour. Permeability of the epidermis to simple diffusion of D-glucose is 8 X 10(-8) cm sec-1 (on basis of gross epidermal area).