Evaluation of a novel device to assess obstructive sleep apnea and body position.

Study objectivesObstructive sleep apnea is a prevalent disease with well-known complications when left untreated. Advances in sleep-disordered breathing diagnosis may increase detection and appropriate treatment. The Wesper device is a recently developed portable system with specialized wearable patches that can measure respiratory effort, derived airflow, estimated air pressure, and body position. This study sought to compare the diagnostic ability of the novel Wesper device with the gold standard of polysomnography.MethodsPatients enrolled in the study underwent simultaneous polysomnography and Wesper device testing in a sleep laboratory setting. Data were collected and scored by readers blinded to all patient information, and the primary reader was blinded to testing method. The accuracy of the Wesper device was determined by calculation of the Pearson correlation and Bland-Altman limits of agreement of apnea-hypopnea indices between testing methods. Adverse events were also recorded.ResultsA total of 53 patients were enrolled in the study and 45 patients were included in the final analysis. Pearson correlation between polysomnography and Wesper device apnea-hypopnea index determinations was 0.951, which met the primary endpoint goal (P = .0003). The Bland-Altman 95% limits of agreement were -8.05 and 6.38, which also met the endpoint goal (P < .001). There were no adverse events or serious adverse events noted.ConclusionsThe Wesper device compares favorably with gold-standard polysomnography. Given the lack of safety concerns, we advocate for further study regarding its utility in diagnosis and management of sleep apnea in the future.CitationRaphelson JR, Ahmed IM, Ancoli-Israel S, et al. Evaluation of a novel device to assess obstructive sleep apnea and body position. J Clin Sleep Med. 2023;19(9):1643-1649

Microorganisms that manipulate complex animal behaviours by affecting the host’s nervous system

Symbioses occur in all higher organisms and have evolved to play an important role in host biology. Researchers have been studying the effects that microbial symbionts have on host biology for decades but have only recently begun to examine how they influence the brain and behaviour. This review aims to provide several examples of different symbionts that have demonstrated the ability to manipulate the behaviour of their hosts and described the current evidence for the molecular mechanisms used by the symbiont to alter the host’s nervous system and modify behaviour to illustrate the common points of interaction between symbiont and host

Osservazioni a Trib. Monza, 14 ottobre 2002

Wolbachia bacteria are endosymbionts that infect approximately 40% of all insect species and are best known for their ability to manipulate host reproductive systems. Though the effect Wolbachia infection has on somatic tissues is less well understood, when present in cells of the adult Drosophila melanogaster brain, Wolbachia exerts an influence over behaviors related to olfaction. Here, we show that a strain of Wolbachia influences male aggression in flies, which is critically important in mate competition. A specific strain of Wolbachia was observed to reduce the initiation of aggressive encounters in Drosophila males compared to the behavior of their uninfected controls. To determine how Wolbachia was able to alter aggressive behavior, we investigated the role of octopamine, a neurotransmitter known to influence male aggressive behavior in many insect species. Transcriptional analysis of the octopamine biosynthesis pathway revealed that two essential genes, the tyrosine decarboxylase and tyramine β-hydroxylase genes, were significantly downregulated in Wolbachia-infected flies. Quantitative chemical analysis also showed that total octopamine levels were significantly reduced in the adult heads

Intensity of mutualism breakdown is determined by temperature not amplification of Wolbachia genes

Wolbachia are maternally transmitted intracellular bacterial symbionts that infect approximately 40% of all insect species. Though several strains of Wolbachia naturally infect Drosophila melanogaster and provide resistance against viral pathogens, or provision metabolites during periods of nutritional stress, one virulent strain, wMelPop, reduces fly lifespan by half, possibly as a consequence of over-replication. While the mechanisms that allow wMelPop to over-replicate are still of debate, a unique tandem repeat locus in the wMelPop genome that contains eight genes, referred to as the “Octomom” locus has been identified and is thought to play an important regulatory role. Estimates of Octomom locus copy number correlated increasing copy number to both Wolbachia bacterial density and increased pathology. Here we demonstrate that infected fly pathology is not dependent on an increased Octomom copy number, but does strongly correlate with increasing temperature. When measured across developmental time, we also show Octomom copy number to be highly variable across developmental time within a single generation. Using a second pathogenic strain of Wolbachia, we further demonstrate reduced insect lifespan can occur independently of a high Octomom locus copy number. Taken together, this data demonstrates that the mechanism/s of wMelPop virulence is more complex than has been previously described

Response to: comment on Rohrscheib et al. 2016 "Intensity of mutualism breakdown is determined by temperature not amplification of Wolbachia genes"

Unlike other intracellular bacteria, Wolbachia genomes are highly labile largely due to the presence of repetitive sequences such as transposons, active phage and high rates of recombination [1–3]. Within the wMelPop genome a locus of considerable instability, referred to as the Octomom locus, has been described by several studies [4–8]. As this locus is one of the few variable loci between wMel (single Octomom locus, low bacterial density and non-pathogenic) and wMelPop (3–12 Octomom loci, high bacterial density and pathogenic) genomes, and no genetic transformation tools are available, there is considerable interest in understanding the link between genotype and phenotype. Chrostek and Teixeira hypothesized “that Octomom region amplification underlies wMelPop virulence” and went on to correlate increased Octomom copy number to increased bacterial density within the host and strength of pathology [5]. Absent from this study was a systematic assessment of temperature, which previous studies had shown to affect wMelPop pathology, and its effect on wMelPop density and Octomom copy number. We hypothesized that temperature would affect Octomom copy number and/or gene expression, and that such changes would affect the strength of pathology [8]. Our study showed that while Octomom copy number did vary over developmental time, no consistent trend was observed among Octomom copy number, bacterial density nor pathology [8]. We determined that temperature, not Octomom copy number or bacterial density, had the greatest effect on wMelPop infected host lifespan. The link between Octomom copy number and pathology was further challenged by our discovery of a pathogenic Wolbachia strain (wMel3562) that maintained a single copy of the Octomom locus, and supports an earlier study of a wMelPop variant that lacks the Octomom locus but which is still pathogenic [7–9]. These observations suggest that at the very least, genetic elements beyond the Octomom locus are responsible for pathology..

Oscillatory brain activity in spontaneous and induced sleep stages in flies

Sleep is a dynamic process comprising multiple stages, each associated with distinct electrophysiological properties and potentially serving different functions. While these phenomena are well described in vertebrates, it is unclear if invertebrates have distinct sleep stages. We perform local field potential (LFP) recordings on flies spontaneously sleeping, and compare their brain activity to flies induced to sleep using either genetic activation of sleep-promoting circuitry or the GABAA agonist Gaboxadol. We find a transitional sleep stage associated with a 7–10 Hz oscillation in the central brain during spontaneous sleep. Oscillatory activity is also evident when we acutely activate sleep-promoting neurons in the dorsal fan-shaped body (dFB) of Drosophila. In contrast, sleep following Gaboxadol exposure is characterized by low-amplitude LFPs, during which dFB-induced effects are suppressed. Sleep in flies thus appears to involve at least two distinct stages: increased oscillatory activity, particularly during sleep induction, followed by desynchronized or decreased brain activity

Octomom copy numbers in <i>w</i>Mel3562 and <i>w</i>MelPop-infected flies.

<p>Octomom copy numbers in <i>w</i>Mel3562 and <i>w</i>MelPop-infected flies.</p

Effect of temperature and fly age on Octomom copy number.

<p>(A) Mean Octomom copy number relative to a single copy <i>w</i>MelPop gene in 11-day old flies reared at 29°C, 24°C, 23°C, 22°C, 21°C and 18°C, as determined by qPCR. (B) Mean Octomom copy number relative to a single copy <i>w</i>MelPop gene in developing flies reared at 24°C (dark-shaded circles) or 21°C (grey-shaded squares) as determined by qPCR. Both flylines were reared at 24°C from embryo to eclosion. Days refer to adult fly age post eclosion. Error bars represent SE.</p

Survival of <i>Drosophila melanogaster</i> infected with <i>w</i>MelPop at different rearing temperatures.

<p>Survival of <i>Drosophila melanogaster</i> infected with <i>w</i>MelPop at different rearing temperatures.</p

Daily <i>w</i>Mel3562 bacterial density in adult <i>D. melanogaster</i>.

<p>Mean relative <i>w</i>Mel3562 density in flies reared at 29°C and 24°C, as determined by qPCR. Errors bars on curves represent SE.</p