Mpox outbreak among men who have sex with men in Amsterdam and Rotterdam, the Netherlands: no evidence for undetected transmission prior to May 2022, a retrospective study

Since May 2022, over 21,000 mpox cases have been reported from 29 EU/EEA countries, predominantly among men who have sex with men (MSM). The Netherlands was the fourth most affected country in Europe, with more than 1,200 cases and a crude notification rate of 70.7 per million population. The first national case was reported on 10 May, yet potential prior transmission remains unknown. Insight into prolonged undetected transmission can help to understand the current outbreak dynamics and aid future public health interventions. We performed a retrospective study and phylogenetic analysis to elucidate whether undetected transmission of human mpox virus (hMPXV) occurred before the first reported cases in Amsterdam and Rotterdam. In 401 anorectal and ulcer samples from visitors to centres for sexual health in Amsterdam or Rotterdam dating back to 14 February 2022, we identified two new cases, the earliest from 6 May. This coincides with the first cases reported in the United Kingdom, Spain and Portugal. We found no evidence of widespread hMPXV transmission in Dutch sexual networks of MSM before May 2022. Likely, the mpox outbreak expanded across Europe within a short period in the spring of 2022 through an international highly intertwined network of sexually active MSM.

EEG time-warping to study non-strictly-periodic EEG signals related to the production of rhythmic movements

BACKGROUND

Many sensorimotor functions are intrinsically rhythmic, and are underlined by neural processes that are functionally distinct from neural responses related to the processing of transient events. EEG frequency tagging is a technique that is increasingly used in neuroscience to study these processes. It relies on the fact that perceiving and/or producing rhythms generates periodic neural activity that translates into periodic variations of the EEG signal. In the EEG spectrum, those variations appear as peaks localized at the frequency of the rhythm and its harmonics.

NEW METHOD

Many natural rhythms, such as music or dance, are not strictly periodic and, instead, show fluctuations of their period over time. Here, we introduce a time-warping method to identify non-strictly-periodic EEG activities in the frequency domain.

RESULTS

EEG time-warping can be used to characterize the sensorimotor activity related to the performance of self-paced rhythmic finger movements. Furthermore, the EEG time-warping method can disentangle auditory- and movement-related EEG activity produced when participants perform rhythmic movements synchronized to an acoustic rhythm. This is possible because the movement-related activity has different period fluctuations than the auditory-related activity.

COMPARISON WITH EXISTING METHODS

With the classic frequency-tagging approach, rhythm fluctuations result in a spreading of the peaks to neighboring frequencies, to the point that they cannot be distinguished from background noise.

CONCLUSIONS

The proposed time-warping procedure is as a simple and effective mean to study natural non-strictly-periodic rhythmic neural processes such as rhythmic movement production, acoustic rhythm perception and sensorimotor synchronization.

Transient hyperpolarization of yeast by glucose and ethanol

At pH 7, addition of glucose under anaerobic conditions to a suspension of the yeast Saccharomyces cerevisiae causes both a transient hyperpolarization and a transient net efflux of K+ from the cells. Hyperpolarization shows a peak at about 3 min and a net K+ efflux at 4-5 min. An additional transient hyperpolarization and net K+ efflux are found after 60-80 and 100 min, respectively. Addition of 2-deoxyglucose instead of glucose does not lead to hyperpolarization of the cells or K+ efflux. At low pH, neither transient hyperpolarization nor a transient K+ efflux are found. With ethanol as substrate and applying aerobic conditions, both a transient hyperpolarization and a transient K+ efflux are found at pH 7. The fluorescent probe 2-(dimethylaminostyryl)-1-ethylpyridinium appears to be useful for probing changes in the membrane potential of S. cerevisiae. It is hypothesized that the hyperpolarization of the cells is due to opening of K+ channels in the plasma membrane. Accordingly, the hyperpolarization of the cells at pH 7 is almost completely abolished by 1.25 mM K+, whereas the same amount of Na+ does not reduce the hyperpolarization.