Digital surface scanning in flap perfusion

Monitoring vascular perfusion of transferred tissue is essential in reconstructive surgery to recognize early flap failure. The aim of this study was to evaluate the ability of a digital surface scanner to detect vascular perfusion disorders through the monitoring of skin colour changes. A total of 160 surface scans of the forearm skin were performed with a TRIOS 3D scanner. Vascular compromise was simulated at different time-points by intermittent occlusion of the blood supply to the forearm skin (first the arterial blood supply and then the venous blood supply). Skin colour changes were examined according to the hue, saturation, and value colour scale. Colour differences were analysed with a paired t-test. Significant differences were observed between the colour of the normal skin and that of the vascular compromised skin (P < 0.01). The surface scanner could distinguish between arterial occlusion and venous congestion (P < 0.01). A digital surface scan is an objective, non-invasive tool to detect early vascular perfusion disorders of the skin.     

Superior efficacy of neoadjuvant chemotherapy and radical cystectomy in cT3-4aN0M0 compared to cT2N0M0 bladder cancer

In this study, we compared complete pathological downstaging (pCD, ≤(y)pT1N0) and overall survival (OS) in patients with cT2 versus cT3–4aN0M0 UC of the bladder undergoing radical cystectomy (RC) with or without neoadjuvant chemo- (NAC) or radiotherapy (NAR). A population-based sample of 5,517 patients, who underwent upfront RC versus NAC + RC or NAR + RC for cT2-4aN0M0 UC between 1995–2013, was identified from the Netherlands Cancer Registry. Data were retrieved from individual patient files and pathology reports. pCD-rates were compared using Chi-square tests and OS was estimated by Kaplan–Meier analyses. Multivariable analyses were conducted to determine odds (OR) and hazard ratios (HR) for pCD-status and OS, respectively. We included 4,504 (82%) patients with cT2 and 1,013 (18%) with cT3–4a UC. Median follow-up was 9.2 years. In cT2 UC, pCD-rate was 25% after upfront RC versus 43% (p < 0.001) and 33% (p = 0.130) after NAC + RC and NAR + RC, respectively. In cT3–4a UC, pCD-rate was 8% after upfront RC versus 37% (p < 0.001) and 16% (p = 0.281) after NAC + RC and NAR + RC, respectively. In cT2 UC, 5-year OS was 57% and 51% for NAC + RC and upfront RC, respectively (p = 0.135), whereas in cT3–4a UC, 5-year OS was 55% for NAC + RC versus 36% for upfront RC (p < 0.001). In multivariable analysis for OS, NAC was beneficial in cT3–4a UC (HR: 0.67, 95%CI 0.51–0.89) but not in cT2 UC (HR: 0.91, 95%CI 0.72–1.15). NAR did not influence OS. In conclusion, NAC + RC was associated with superior pCD compared to RC alone and NAR + RC. Superior OS for NAC + RC compared to RC alone was especially evident in cT3–4a disease.     

From clock to functional pacemaker

In mammals, the central pacemaker that coordinates 24‐hr rhythms is located in the suprachiasmatic nucleus (SCN). Individual neurons of the SCN have a molecular basis for rhythm generation and hence, they function as cell autonomous oscillators. Communication and synchronization among these neurons are crucial for obtaining a coherent rhythm at the population level, that can serve as a pace making signal for brain and body. Hence, the ability of single SCN neurons to produce circadian rhythms is equally important as the ability of these neurons to synchronize one another, to obtain a bona fide pacemaker at the SCN tissue level. In this chapter we will discuss the mechanisms underlying synchronization, and plasticity herein, which allows adaptation to changes in day length. Furthermore, we will discuss deterioration in synchronization among SCN neurons in aging, and gain in synchronization by voluntary physical activity or exercise.     

Pathological responses to single‐pulse electrical stimuli in epilepsy: The role of feedforward inhibition

Delineation of epileptogenic cortex in focal epilepsy patients may profit from single‐pulse electrical stimulation during intracranial EEG recordings. Single‐pulse electrical stimulation evokes early and delayed responses. Early responses represent connectivity. Delayed responses are a biomarker for epileptogenic cortex, but up till now, the precise mechanism generating delayed responses remains elusive. We used a data‐driven modelling approach to study early and delayed responses. We hypothesized that delayed responses represent indirect responses triggered by early response activity and investigated this for 11 patients. Using two coupled neural masses, we modelled early and delayed responses by combining simulations and bifurcation analysis. An important feature of the model is the inclusion of feedforward inhibitory connections. The waveform of early responses can be explained by feedforward inhibition. Delayed responses can be viewed as second‐order responses in the early response network which appear when input to a neural mass falls below a threshold forcing it temporarily to a spiking state. The combination of the threshold with noisy background input explains the typical stochastic appearance of delayed responses. The intrinsic excitability of a neural mass and the strength of its input influence the probability at which delayed responses to occur. Our work gives a theoretical basis for the use of delayed responses as a biomarker for the epileptogenic zone, confirming earlier clinical observations. The combination of early responses revealing effective connectivity, and delayed responses showing intrinsic excitability, makes single‐pulse electrical stimulation an interesting tool to obtain data for computational models of epilepsy surgery.