Cuttlefish adopt disruptive camouflage under dynamic lighting.

Many animals avoid detection or recognition using camouflage tailored to the visual features of their environment.1,2,3 The appearance of those features, however, can be affected by fluctuations in local lighting conditions, making them appear different over time.4,5 Despite dynamic lighting being common in many terrestrial and aquatic environments, it is unknown whether dynamic lighting influences the camouflage patterns that animals adopt. Here, we test whether a common form of underwater dynamic lighting, consisting of moving light bands that can create local fluctuations in the intensity of light ("water caustics"), affects the camouflage of cuttlefish (Sepia officinalis). Owing to specialized pigment cells (chromatophores) in the skin,6 these cephalopod mollusks can dynamically adjust their body patterns in response to features of their visual scene.7,8,9 Although cuttlefish resting on plain or patterned backgrounds usually expressed uniform or disruptive body patterns, respectively,10,11,12 exposure to these backgrounds in dynamic lighting induced stronger disruptive patterns regardless of the background type. Dynamic lighting increased the maximum contrast levels within scenes, and these maximum contrast levels were associated with the degree of cuttlefish disruptive camouflage. This adoption of disruptive camouflage in dynamically lit scenes may be adaptive, reducing the likelihood of detection, or alternatively, it could represent a constraint on visual processing.

Predatory trumpetfish conceal themselves from their prey by swimming alongside other fish.

Many animals use camouflage to avoid detection by others, yet even the most inconspicuous objects become detectable against the background when moving1,2. One way to reduce detection while moving would be to 'hide' behind the movements of objects or other animals3. Here, we demonstrate experimentally that a common marine predator, the trumpetfish (Aulostomus maculatus), can conceal its approach from its prey by performing a behaviour known as 'shadowing' - swimming closely next to another, larger and non-predatory fish3,4,5. Our findings reveal how predators can actively use another animal as a form of concealment to reduce detection by prey.

Polarization vision mitigates visual noise from flickering light underwater.

In shallow water, downwelling light is refracted from surface waves onto the substrate creating bands of light that fluctuate in both time and space, known as caustics. This dynamic illumination can be a visual hindrance for animals in shallow underwater environments. Animals in such habitats may have evolved to use polarization vision for discriminating objects while ignoring the variations in illumination caused by caustics. To explore this possibility, crabs (Carcinus maenas) and cuttlefish (Sepia officinalis), both of which have polarization vision, were presented with moving stimuli overlaid with caustics. Dynamic caustics inhibited the detection of an intensity-based stimulus but not when these stimuli were polarized. This study is the first to demonstrate that polarization vision reduces the negative impacts that dynamic illumination can have on visual perception.

Polarization contrasts and their effect on the gaze stabilization of crustaceans.

Many animals go to great lengths to stabilize their eyes relative to the visual scene and do so to enhance the localization of moving objects and to functionally partition the visual system relative to the outside world. An important cue that is used to control these stabilization movements is contrast within the visual surround. Previous studies on insects, spiders and fish have shown that gaze stabilization is achromatic ('colour blind'), meaning that chromatic contrast alone (in the absence of apparent intensity contrasts) does not contribute to gaze stabilization. Following the assumption that polarization vision is analogous in many ways to colour vision, the present study shows that five different crustacean species do not use the polarization of light alone for gaze stabilization, despite being able to use this modality for detecting predator-like objects. This work therefore suggests that the gaze stabilization in many crustaceans cannot be elicited by the polarization of light alone.

Polarization contrasts and their effect on the gaze stabilization of crustaceans.

Many animals go to great lengths to stabilize their eyes relative to the visual scene and do so to enhance the localization of moving objects and to functionally partition the visual system relative to the outside world. An important cue that is used to control these stabilization movements is contrast within the visual surround. Previous studies on insects, spiders and fish have shown that gaze stabilization is achromatic ('colour blind'), meaning that chromatic contrast alone (in the absence of apparent intensity contrasts) does not contribute to gaze stabilization. Following the assumption that polarization vision is analogous in many ways to colour vision, the present study shows that five different crustacean species do not use the polarization of light alone for gaze stabilization, despite being able to use this modality for detecting predator-like objects. This work therefore suggests that the gaze stabilization in many crustaceans cannot be elicited by the polarization of light alone.

Diagnostic value of laboratory parameters for the discrimination between erysipelas and limited cellulitis.

BACKGROUND AND OBJECTIVES: Erysipelas, caused by beta-hemolytic streptococci, and limited cellulitis, frequently caused by Staphylococcus aureus or other bacteria, are skin and soft tissue infections characterized by typical clinical signs. However, despite the therapeutical relevance they are often not differentiated (e.g in clinical trials). Erysipelas are efficiently treated with penicillin, while limited cellulitis is treated with more wide-spectrum antibiotics. This study investigates whether parameters such as CRP, blood counts or novel parameters like immature granulocytes could serve as biomarkers to distinguish between these entities. PATIENTS AND METHODS: For this retrospective analysis 163 patients were included. We compared laboratory markers in patients with erysipelas (n = 68) to those with limited cellulitis (n = 41) of the leg. Both erysipelas and limited cellulitis were defined clinically, with an additional aspect for erysipelas being a prompt response to penicillin. RESULTS: Erysipelas were characterized by higher levels of inflammation. CRP and leukocyte counts are the best parameters to discriminate between both infections. A CRP value ≥ 3.27 mg/dl indicated the diagnosis of erysipelas with 75 % sensitivity and 73.2 % specificity. CONCLUSIONS: Our results support the thesis that erysipelas and limited cellulitis are distinct infections as defined in the German guidelines and that an assessment of CRP and leukocytes is useful for differential diagnosis.

[Surgical treatment for chronic leg ulcer]. / Chirurgische Versorgung des chronischen Ulkus am Bein.

Leg ulcers pose a therapeutic challenge due to a chronic healing process. Conservative wound dressings are initially the treatment of choice, but their effectiveness in therapy-refractory wounds is limited. In these cases, multiple mechanical debridement in combination with split-thickness skin grafts (STSG) are a simple and safe treatment option for ulcer coverage. Additional therapy with negative pressure wound therapy (NPWT) improves the surgical outcome by promoting ulcer granulation, continuous elimination of exsudate and blood as well as increased contact pressure on the skin graft. After transplantation, the split skin graft requires daily wound dressings until it has fully healed after approximately 3 weeks.

Diagnostic Value of Laboratory Parameters for Distinguishing Between Herpes Zoster and Bacterial Superficial Skin and Soft Tissue Infections.

Clinical differentiation between herpes zoster and bacterial superficial skin and soft tissue infections of the face can be difficult. In addition, diagnosis can be complicated by bacterial superinfection of lesional herpes zoster. The aim of this study was to determine whether inflammatory parameters, such as C-reactive protein (CRP) and blood counts, might be reliable biomarkers to distinguish between skin and soft tissue infections and herpes zoster when the face is infected. The study data (multivariate analysis and area under the curve) identified CRP (0.880) and leukocytes (0.730) together as the parameters that best discriminate between skin and soft tissue infections and herpes zoster. A CRP threshold ≥ 2.05 mg/dl indicated a diagnosis of skin and soft tissue infection with a sensitivity of 80% and specificity of 83.8%. For leukocytes ≥ 7.3×109/l, diagnosis of skin and soft tissue infection had a sensitivity of 75% and specificity of 67.6%. Thus, when differential diagnosis is difficult, CRP and leukocytes should be determined, while parameters such as neutrophils or immature granulocytes do not add diagnostic value.

[Raynaud's phenomenon : Practical management for dermatologists]. / Raynaud-Phänomen : Praktisches Management durch den Dermatologen.

Raynaud's phenomenon (RP) is a painful vasospasm of small arteries, localised in fingers and toes. Typically these body parts turn white (ischemia), then blue (deoxygenation) and then red (reperfusion). Two different types of RP exist: the common primary RP without underlying disease and the rare secondary RP, mostly associated with rheumatoid diseases such as systemic sclerosis. Thus, the dermatologist has to be aware of this condition. In this article the clinical criteria, differential diagnoses, diagnostic considerations and treatment options are discussed.