Gender differences in adult atopic dermatitis and clinical implication: Results from a nationwide multicentre study

BACKGROUND

Atopic dermatitis (AD) is a common inflammatory skin disease that affects both children and adults. However, limited research has been conducted on gender differences in AD.

OBJECTIVES

This study aimed to assess gender differences in adult AD patients, focusing on demographic and clinical features, comorbidities and treatment approaches.

METHODS

In this multicentre, observational, cross-sectional study, we enrolled 686 adult patients with AD (357 males and 329 females). For each patient, we collected demographic data (age and sex), anthropometric measurements (weight, height, hip circumference, waist circumference and waist-to-hip ratio), clinical information (onset age, disease duration, severity, itching intensity, impact on quality of life) and noted comorbidities (metabolic, atopic and other). We recorded past and current topical and systemic treatments. We analysed all collected data using statistical techniques appropriate for both quantitative and qualitative variables. Multiple correspondence analysis (MCA) was employed to evaluate the relationships among all clinical characteristics of the patients.

RESULTS

We found no differences in age at onset, disease duration, severity and quality of life impact between males and females. Males exhibited higher rates of hypertriglyceridaemia and hypertension. No significant gender differences were observed in atopic or other comorbidities. Treatment approaches were overlapping, except for greater methotrexate use in males. MCA revealed distinct patterns based on gender, disease severity, age of onset, treatment and quality of life. Adult males with AD had severe disease, extensive treatments and poorer quality of life, while adult females had milder disease, fewer treatments and moderate quality of life impact.

CONCLUSIONS

Our study reveals that gender differences in adult AD patients are largely due to inherent population variations rather than disease-related disparities. However, it highlights potential undertreatment of females with moderate AD and quality of life impact, emphasizing the need for equitable AD treatment. JAK inhibitors may offer a solution for gender-based therapeutic parity.

Minorities drive growth resumption in cross-feeding microbial communities

Microbial communities are fundamental to life on Earth. Different strains within these communities are often connected by a highly connected metabolic network, where the growth of one strain depends on the metabolic activities of other community members. While distributed metabolic functions allow microbes to reduce costs and optimize metabolic pathways, they make them metabolically dependent. Here, we hypothesize that such dependencies can be detrimental in situations where the external conditions change rapidly, as they often do in natural environments. After a shift in external conditions, microbes need to remodel their metabolism, but they can only resume growth once partners on which they depend have also adapted to the new conditions. It is currently not well understood how microbial communities resolve this dilemma and how metabolic interactions are reestablished after an environmental shift. To address this question, we investigated the dynamical responses to environmental perturbation by microbial consortia with distributed anabolic functions. By measuring the regrowth times at the single-cell level in spatially structured communities, we found that metabolic dependencies lead to a growth delay after an environmental shift. However, a minority of cells-those in the immediate neighborhood of their metabolic partners-can regrow quickly and come to numerically dominate the community after the shift. The spatial arrangement of a microbial community is thus a key factor in determining the communities' ability to maintain metabolic interactions and growth in fluctuating conditions. Our results suggest that environmental fluctuations can limit the emergence of metabolic dependencies between microorganisms.

Line-field confocal optical coherence tomography of psoriasis, eczema and lichen planus: a case series with histopathological correlation

BACKGROUND

Line-field confocal optical coherence tomography (LC-OCT) is a novel, non-invasive technique that provides in vivo, high-resolution images in both vertical and horizontal sections.

OBJECTIVES

The aim of the study was to evaluate LC-OCT imaging in some inflammatory disorders and to correlate the resulting features with histopathology.

METHODS

The retrospective study included patients with histopathological confirmed diagnosis of plaque psoriasis, atopic eczema and lichen planus, who were imaged with LC-OCT before the biopsy. LC-OCT was performed with the commercially available LC-OCT device.

RESULTS

A total of 15 adult patients with histopathologically proven plaque psoriasis (N: 5), atopic eczema (N: 5) and lichen planus (N: 5) were included. In all cases, LC-OCT allowed the in vivo recognition of the main microscopic features of the examined inflammatory skin disease, with a strong correlation with histopathology.

CONCLUSIONS

Although future studies on larger series of patients are necessary, LC-OCT, based on these preliminary findings, may represent a promising tool in inflammatory skin disorders with potential applications including enhanced diagnosis, biopsy guidance, follow-up and treatment monitoring.

Moderate to severe atopic dermatitis in adolescents treated with dupilumab: a multicenter Italian real-world experience

Background

Moderate‐to‐severe atopic dermatitis (AD) in the adolescence is a high burden disease, and its treatment can be very challenging due to paucity of approved systemic drugs for this age and their side‐effects. Dupilumab was recently approved for treatment of adolescent AD.

Objectives

A multicentre, prospective, real‐world study on the effectiveness and safety of dupilumab in adolescents (aged from ≥12 to <18 years) with moderate‐to‐severe AD was conducted. The main AD clinical phenotypes were also examined.

Methods

Data of adolescents with moderate‐to‐severe AD treated with dupilumab at label dosage for 16 weeks were collected. Treatment outcome was assessed by EASI, NRS itch, NRS sleep loss and CDLQI scores at baseline and after 16 weeks of treatment. The clinical scores were also evaluated according to clinical phenotypes.

Results

One hundred and thirty‐nine adolescents were enrolled in the study. Flexural eczema and head and neck eczema were the most frequent clinical phenotypes, followed by hand eczema and portrait‐like dermatitis. Coexistence of more than 1 phenotype was documented in 126/139 (88.5%) adolescents. Three patients (2.1%) contracted asymptomatic SARS‐CoV‐2 infection and 1 of the discontinued dupilumab treatment before the target treatment period. A significant improvement in EASI, NRS itch, NRS sleep loss and CDLQI was observed after 16 weeks of treatment with dupilumab. This outcome was better than that observed in clinical trials. Dupilumab resulted effective in all AD phenotypes, especially in diffuse eczema. Twenty‐eight (20.1%) patients reported adverse events, conjunctivitis and flushing being the most frequent. None of patients discontinued dupilumab due to adverse event.

Conclusions

Dupilumab in adolescent AD showed excellent effectiveness at week 16 with consistent improvement of all clinical scores. Moreover, dupilumab showed a good safety profile also in this COVID‐19 pandemic era.

Two different cell-cycle processes determine the timing of cell division in Escherichia coli

Cells must control the cell cycle to ensure that key processes are brought to completion. In Escherichia coli, it is controversial whether cell division is tied to chromosome replication or to a replication-independent inter-division process. A recent model suggests instead that both processes may limit cell division with comparable odds in single cells. Here, we tested this possibility experimentally by monitoring single-cell division and replication over multiple generations at slow growth. We then perturbed cell width, causing an increase of the time between replication termination and division. As a consequence, replication became decreasingly limiting for cell division, while correlations between birth and division and between subsequent replication-initiation events were maintained. Our experiments support the hypothesis that both chromosome replication and a replication-independent inter-division process can limit cell division: the two processes have balanced contributions in non-perturbed cells, while our width perturbations increase the odds of the replication-independent process being limiting.

Comorbidities and treatment patterns in adult patients with atopic dermatitis: results from a nationwide multicenter study

Adult atopic dermatitis (adult AD) is a systemic inflammatory disorder, whose relationship with immune-allergic and metabolic comorbidities is not well established yet. Moreover, treatment of mild-to-moderate and severe atopic dermatitis needs standardization among clinicians. The aim of this study was to evaluate the distribution of comorbidities, including metabolic abnormalities, rhinitis, conjunctivitis, asthma, alopecia and sleep disturbance, according to severity of adult AD, and describe treatments most commonly used by Italian dermatologists. Retrospective, observational, nationwide study of adult patients over a 2-year period was performed. Clinical and laboratory data were obtained through review of medical records of patients aged ≥ 18 years, followed in 23 Italian National reference centres for atopic dermatitis between September 2016 and September 2018. The main measurements evaluated were disease severity, atopic and metabolic comorbidities, treatment type and duration. Six-hundred and eighty-four adult patients with AD were included into the study. Atopic, but not metabolic conditions, except for hypertension, were significantly associated with having moderate-to-severe AD in young adult patients. Disease duration was significantly associated with disease severity. Oral corticosteroids and cyclosporine were the most widely used immunosuppressant. Our study seems confirm the close relationship between adult AD and other atopic conditions, further long-term cohort studies on patients affected by adult AD need to be performed to evaluate the complex relationship between adult AD disease severity and metabolic comorbidities.

Developments and challenges in dermatology: an update from the Interactive Derma Academy (IDeA) 2019

The 2019 Interactive Derma Academy (IDeA) meeting was held in Lisbon, Portugal, 10-12 May, bringing together leading dermatology experts from across Europe, the Middle East and Asia. Over three days, the latest developments and challenges in relation to the pathophysiology, diagnosis, evaluation and management of dermatological conditions were presented, with a particular focus on acne, atopic dermatitis (AD) and actinic keratosis (AK). Interesting clinical case studies relating to these key topics were discussed with attendees to establish current evidence-based best practices. Presentations reviewed current treatments, potential therapeutic approaches and key considerations in the management of acne, AK and AD, and discussed the importance of the microbiome in these conditions, as well as the provision of patient education/support. It was highlighted that active treatment is not always required for AK, depending on patient preferences and clinical circumstances. In addition to presentations, two interactive workshops on the diagnosis and treatment of sexually transmitted infections/diseases (STIs/STDs) presenting to the dermatology clinic, and current and future dermocosmetics were conducted. The potential for misdiagnosis of STIs/STDs was discussed, with dermoscopy and/or reflectance confocal microscopy suggested as useful diagnostic techniques. In addition, botulinum toxin was introduced as a potential dermocosmetic, and the possibility of microbiome alteration in the treatment of dermatological conditions emphasized. Furthermore, several challenges in dermatology, including the use of lasers, the complexity of atopic dermatitis, wound care, use of biosimilars and application of non-invasive techniques in skin cancer diagnosis were reviewed. In this supplement, we provide an overview of the presentations and discussions from the fourth successful IDeA meeting, summarizing the key insights shared by dermatologists from across the globe.

The 2020 International Alliance for the Control of Scabies Consensus Criteria for the Diagnosis of Scabies

BACKGROUND

Scabies is a common parasitic skin condition that causes considerable morbidity globally. Clinical and epidemiological research for scabies has been limited by a lack of standardization of diagnostic methods.

OBJECTIVES

To develop consensus criteria for the diagnosis of common scabies that could be implemented in a variety of settings.

METHODS

Consensus diagnostic criteria were developed through a Delphi study with international experts. Detailed recommendations were collected from the expert panel to define the criteria features and guide their implementation. These comments were then combined with a comprehensive review of the available literature and the opinion of an expanded group of international experts to develop detailed, evidence-based definitions and diagnostic methods.

RESULTS

The 2020 International Alliance for the Control of Scabies (IACS) Consensus Criteria for the Diagnosis of Scabies include three levels of diagnostic certainty and eight subcategories. Confirmed scabies (level A) requires direct visualization of the mite or its products. Clinical scabies (level B) and suspected scabies (level C) rely on clinical assessment of signs and symptoms. Evidence-based, consensus methods for microscopy, visualization and clinical symptoms and signs were developed, along with a media library.

CONCLUSIONS

The 2020 IACS Criteria represent a pragmatic yet robust set of diagnostic features and methods. The criteria may be implemented in a range of research, public health and clinical settings by selecting the appropriate diagnostic levels and subcategories. These criteria may provide greater consistency and standardization for scabies diagnosis. Validation studies, development of training materials and development of survey methods are now required. What is already known about this topic? The diagnosis of scabies is limited by the lack of accurate, objective tests. Microscopy of skin scrapings can confirm the diagnosis, but it is insensitive, invasive and often impractical. Diagnosis usually relies on clinical assessment, although visualization using dermoscopy is becoming increasingly common. These diagnostic methods have not been standardized, hampering the interpretation of findings from clinical research and epidemiological surveys, and the development of scabies control strategies. What does this study add? International consensus diagnostic criteria for common scabies were developed through a Delphi study with global experts. The 2020 International Alliance for the Control of Scabies (IACS) Criteria categorize diagnosis at three levels of diagnostic certainty (confirmed, clinical and suspected scabies) and eight subcategories, and can be adapted to a range of research and public health settings. Detailed definitions and figures are included to aid training and implementation. The 2020 IACS Criteria may facilitate the standardization of scabies diagnosis.

Dermoscopy of genital diseases: a review

The male and female external genital regions are anatomical areas in which various types of skin disorders may occur. Although most of these conditions can be diagnosed by means of clinical examination and an accurate medical history, in most cases further investigations with time-consuming and/or invasive procedures are needed in order to reach the correct diagnosis. Dermoscopy, as a modern non-invasive tool, is able to better diagnose pigmented and non-pigmented skin tumours along with various inflammatory and infectious skin and appendage disorders. The aim of this paper was to provide a review of the use of dermoscopy in genital disorders based on published data and to include personal experience gained from real life, focusing on any possible gender difference and whether disease mucosal/semimucosal dermoscopy features may differ from those observed on the skin. In conclusion, genital dermoscopy should always be considered during clinical inspection in order to enhance the diagnosis or to rule out those conditions that may look similar but that show a different dermoscopy pattern, thus narrowing down the differential diagnoses and avoiding unnecessary invasive investigations.

Evidence for a 'window of opportunity' in hidradenitis suppurativa treated with adalimumab: a retrospective, real-life multicentre cohort study

BACKGROUND

The anti-tumour necrosis factor (TNF)-α adalimumab is the only licenced biologic for moderate-to-severe hidradenitis suppurativa (HS). No predictors of response have been identified so far.

OBJECTIVES

To identify clinical parameters predicting response to adalimumab and confirm its efficacy/safety.

METHODS

The data of 389 patients with HS treated with adalimumab in 21 Italian centres were reviewed. Sex, age at onset/diagnosis/baseline, body mass index, smoking, phenotype, previous treatments, concomitant antibiotics and 'therapeutic delay', defined as the time from HS onset to adalimumab initiation, were assessed. Response to adalimumab and its impact on quality of life (QoL) were evaluated using the Hidradenitis Suppurativa Clinical Response (HiSCR) and the Dermatology Life Quality Index (DLQI) or the Visual Analogue Scale for pain (VAS pain), respectively. Logistic regression analysis was performed.

RESULTS

The therapeutic delay correlated to lack of response to adalimumab at week 16 [odds ratio (OR) 1·92 for therapeutic delay > 10 years; 95% confidence interval (CI) 1·28-2·89; P = 0·0016). HiSCR was achieved in 43·7% and 53·9% patients at week 16 and 52, respectively. Significant reductions in both DLQI and VAS pain were found between week 16 vs. baseline (P < 0·0001 for both) and week 52 vs. baseline (P < 0·0001 for both). Previous immunosuppressants inversely correlated to HiSCR at week 52 (OR = 1·74, 95% CI 1·04-2·91, P = 0·0342).

CONCLUSIONS

Inverse correlation between therapeutic delay and clinical response was found, supporting early adalimumab use and providing evidence for a 'window of opportunity' in HS treatment. Adalimumab efficacy and safety were confirmed, along with patients' QoL improvement. Immunosuppressants could negatively influence the response to adalimumab inducing a switch to non-TNF-α-driven pathways.

Creation of a severity index for hidradenitis suppurativa that includes a validated quality-of-life measure: the HIDRAscore

Background

Hidradenitis suppurativa (HS) is a chronic, debilitating disease with a considerable effect on patient quality of life. Its clinical severity can be measured using different scoring systems; however, few of them include patient‐centred parameters.

Objective

To create a new scoring system for HS that includes a quality‐of‐life instrument, the HIDRAdisk.

Methods

This post hoc analysis was carried out within the framework of a multicentre, longitudinal, epidemiologic study conducted over 9 months on quality‐of‐life aspects of HS. The new severity score was created using as reference a question from the Subject Satisfaction Questionnaire (SSQ) concerning the severity of HS as evaluated by the patient. Associated variables were selected using univariable and multivariable logistic regression models. The discriminant capabilities of the final model and of the final score were evaluated by the area under the receiver operating characteristic curve and the Hosmer–Lemeshow test.

Results

The study population included 308 patients with HS of any severity grade. According to the results of the regression models, the variables associated with the reference SSQ measure were number of inflammatory nodules, abscesses and draining fistulas; the HIDRAdisk score; and the number of subumbilical lesions. The HIDRAscore is obtained by the sum of the scores associated with the number of these parameters. Possible scores range from 0 to 10.

Conclusion

The HIDRAscore is a new scoring system for HS severity which, in addition to the clinical evaluation by the physician, includes a validated patient‐reported outcome measure, the HIDRAdisk.

The patient journey: a voyage from diagnosis to hidradenitis suppurativa multidisciplinary unit

BACKGROUND

Hidradenitis suppurativa (HS) is an inflammatory, recurrent and debilitating chronic skin disease that is often worsened by comorbidities, with a destructive impact on the social and working life of the patient. The low awareness of patients and clinicians regarding HS, together with weak coordination between specialists who manage the clinical care of these patients, may result in a burdening diagnostic and therapeutic delay, lowering efficacy of therapies and worsening prognosis and patients' QoL.

OBJECTIVES

To rule out these critical aspects, a HS-Multidisciplinary Unit with a hierarchical organization is proposed.

METHODS

Based on previously published models of a multidisciplinary unit, a hierarchical structure of a HS-dedicated multidisciplinary unit was designed.

RESULTS

In this model, an operational core constituted by four healthcare professionals constantly working as team, is supported by a large panel of consultants, local dermatologists and general practitioners, helping in HS patient management.

CONCLUSIONS

This standardization would imply an optimization of professional resources, an amelioration of patient's quality of life, and a shortening of patient journey.

Maximal information transmission is compatible with ultrasensitive biological pathways

Cells are often considered input-output devices that maximize the transmission of information by converting extracellular stimuli (input) via signaling pathways (communication channel) to cell behavior (output). However, in biological systems outputs might feed back into inputs due to cell motility, and the biological channel can change by mutations during evolution. Here, we show that the conventional channel capacity obtained by optimizing the input distribution for a fixed channel may not reflect the global optimum. In a new approach we analytically identify both input distributions and input-output curves that optimally transmit information, given constraints from noise and the dynamic range of the channel. We find a universal optimal input distribution only depending on the input noise, and we generalize our formalism to multiple outputs (or inputs). Applying our formalism to Escherichia coli chemotaxis, we find that its pathway is compatible with optimal information transmission despite the ultrasensitive rotary motors.

Recommendations for rosacea diagnosis, classification and management: update from the global ROSacea COnsensus 2019 panel

Background

A transition from a subtyping to a phenotyping approach in rosacea is underway, allowing individual patient management according to presenting features instead of categorization by predefined subtypes. The ROSacea COnsensus (ROSCO) 2017 recommendations further support this transition and align with guidance from other working groups.

Objectives

To update and extend previous global ROSCO recommendations in line with the latest research and continue supporting uptake of the phenotype approach in rosacea through clinical tool development.

Methods

Nineteen dermatologists and two ophthalmologists used a modified Delphi approach to reach consensus on statements pertaining to critical aspects of rosacea diagnosis, classification and management. Voting was electronic and blinded.

Results

Delphi statements on which the panel achieved consensus of ≥ 75% voting ‘Agree’ or ‘Strongly agree’ are presented. The panel recommends discussing disease burden with patients during consultations, using four questions to assist conversations. The primary treatment objective should be achievement of complete clearance, owing to previously established clinical benefits for patients. Cutaneous and ocular features are defined. Treatments have been reassessed in line with recent evidence and the prior treatment algorithm updated. Combination therapy is recommended to benefit patients with multiple features. Ongoing monitoring and dialogue should take place between physician and patients, covering defined factors to maximize outcomes. A prototype clinical tool (Rosacea Tracker) and patient case studies have been developed from consensus statements.

Conclusions

The current survey updates previous recommendations as a basis for local guideline development and provides clinical tools to facilitate a phenotype approach in practice and improve rosacea patient management.

What's already known about this topic?

A transition to a phenotype approach in rosacea is underway and is being recommended by multiple working groups.

New research has become available since the previous ROSCO consensus, necessitating an update and extension of recommendations.

What does this study add?

We offer updated global recommendations for clinical practice that account for recent research, to continue supporting the transition to a phenotype approach in rosacea.

We present prototype clinical tools to facilitate use of the phenotype approach in practice and improve management of patients with rosacea.

Linked Comment: Elewski. Br J Dermatol 2020; 182:1090–1091.

Plain language summary available online

Follicular occlusion tetrad in a male patient with pachyonychia congenita: clinical and genetic analysis

The case of a 24-year-old male patient affected by follicular occlusion tetrad (acne conglobata, hidradenitis suppurativa, pilonidal cyst and dissecting cellulitis of the scalp) associated with clinical signs of pachyonychia congenita (PC)-2 (focal palmoplantar keratoderma, plantar pain, onycodystrophy and multiple cysts) is reported. The diagnosis was supported by genetic analysis that showed heterozygous mutation within the exon 1 of KRT17 gene. This case may reflect different expressions of a phenotypic spectrum induced by a common genetic alteration.

Standardization of dermoscopic terminology and basic dermoscopic parameters to evaluate in general dermatology (non-neoplastic dermatoses): an expert consensus on behalf of the International Dermoscopy Society

BACKGROUND

Over the last few years, several articles on dermoscopy of non-neoplastic dermatoses have been published, yet there is poor consistency in the terminology among different studies.

OBJECTIVES

We aimed to standardize the dermoscopic terminology and identify basic parameters to evaluate in non-neoplastic dermatoses through an expert consensus.

METHODS

The modified Delphi method was followed, with two phases: (i) identification of a list of possible items based on a systematic literature review and (ii) selection of parameters by a panel of experts through a three-step iterative procedure (blinded e-mail interaction in rounds 1 and 3 and a face-to-face meeting in round 2). Initial panellists were recruited via e-mail from all over the world based on their expertise on dermoscopy of non-neoplastic dermatoses.

RESULTS

Twenty-four international experts took part in all rounds of the consensus and 13 further international participants were also involved in round 2. Five standardized basic parameters were identified: (i) vessels (including morphology and distribution); (ii) scales (including colour and distribution); (iii) follicular findings; (iv) 'other structures' (including colour and morphology); and (v) 'specific clues'. For each of them, possible variables were selected, with a total of 31 different subitems reaching agreement at the end of the consensus (all of the 29 proposed initially plus two more added in the course of the consensus procedure).

CONCLUSIONS

This expert consensus provides a set of standardized basic dermoscopic parameters to follow when evaluating inflammatory, infiltrative and infectious dermatoses. This tool, if adopted by clinicians and researchers in this field, is likely to enhance the reproducibility and comparability of existing and future research findings and uniformly expand the universal knowledge on dermoscopy in general dermatology. What's already known about this topic? Over the last few years, several papers have been published attempting to describe the dermoscopic features of non-neoplastic dermatoses, yet there is poor consistency in the terminology among different studies. What does this study add? The present expert consensus provides a set of standardized basic dermoscopic parameters to follow when evaluating inflammatory, infiltrative and infectious dermatoses. This consensus should enhance the reproducibility and comparability of existing and future research findings and uniformly expand the universal knowledge on dermoscopy in general dermatology.

Sex-related differences of clinical features in hidradenitis suppurativa: analysis of an Italian-based cohort

The clinical characteristics associated with hidradenitis suppurativa (HS) severity are poorly understood. In this study, 124 patients with HS from 6 Italian dermatology centres participated in this study. Disease severity was assessed using the Hidradenitis Suppurativa Physician's Global Assessment score (HS-PGA) and Hurley score. The impact of clinical characteristics on disease severity was assessed by logistic regression. Clinical characteristics were similar between men (n = 53) and women (n = 71). Disease severity was also similar; 75% of the patients had Hurley stage II or III disease, and > 60% had moderate, severe or very severe HS as judged by HS-PGA. Lesions were more frequent in the gluteal region in men (32.3% in men vs. 8.7% in women, P < 0.001) and more frequent on the breast in women (16.3% in women vs. 4.6% in men, P = 0.02). Obesity was associated with increased disease severity as measured by HS-PGA (OR: 3.28, 95% CI 1.55-6.95, P < 0.01) and Hurley classification (OR: 3.22, 95% CI 1.34-7.31, P < 0.01). Although severity of HS is similar between the sexes, the localization of lesions is different.

Concurrent processes set E. coli cell division

A cell can divide only upon completion of chromosome segregation; otherwise, its daughters would lose genetic material. However, we do not know whether the partitioning of chromosomes is the key event for the decision to divide. We show how key trends in single-cell data reject the classic idea of replication-segregation as the rate-limiting process for cell division. Instead, the data agree with a model where two concurrent processes (setting replication initiation and interdivision time) set cell division on competing time scales. During each cell cycle, division is set by the slowest process (an "AND" gate). The concept of transitions between cell cycle stages as decisional processes integrating multiple inputs instead of cascading from orchestrated steps can affect the way we think of the cell cycle in general.

The Empirical Fluctuation Pattern of E. coli Division Control

In physics, it is customary to represent the fluctuations of a stochastic system at steady state in terms of linear response to small random perturbations. Previous work has shown that the same framework describes effectively the trade-off between cell-to-cell variability and correction in the control of cell division of single E. coli cells. However, previous analyses were motivated by specific models and limited to a subset of the measured variables. For example, most analyses neglected the role of growth rate variability. Here, we take a comprehensive approach and consider several sets of available data from both microcolonies and microfluidic devices in different growth conditions. We evaluate all the coupling coefficients between the three main measured variables (interdivision times, cell sizes and individual-cell growth rates). The linear-response framework correctly predicts consistency relations between a priori independent experimental measurements, which confirms its validity. Additionally, the couplings between the cell-specific growth rate and the other variables are typically non zero. Finally, we use the framework to detect signatures of mechanisms in experimental data involving growth rate fluctuations, finding that (1) noise-generating coupling between size and growth rate is a consequence of inter-generation growth rate correlations and (2) the correlation patterns agree with a near-adder model where the added size has a dependence on the single-cell growth rate. Our findings define relevant constraints that any theoretical description should reproduce, and will help future studies aiming to falsify some of the competing models of the cell cycle existing today in the literature.

Drift and Behavior of E. coli Cells

Chemotaxis of the bacterium Escherichia coli is well understood in shallow chemical gradients, but its swimming behavior remains difficult to interpret in steep gradients. By focusing on single-cell trajectories from simulations, we investigated the dependence of the chemotactic drift velocity on attractant concentration in an exponential gradient. Whereas maxima of the average drift velocity can be interpreted within analytical linear-response theory of chemotaxis in shallow gradients, limits in drift due to steep gradients and finite number of receptor-methylation sites for adaptation go beyond perturbation theory. For instance, we found a surprising pinning of the cells to the concentration in the gradient at which cells run out of methylation sites. To validate the positions of maximal drift, we recorded single-cell trajectories in carefully designed chemical gradients using microfluidics.

A proposed scoring system for assessing the severity of actinic keratosis on the head: actinic keratosis area and severity index

BACKGROUND

Actinic keratosis (AK) severity is currently evaluated by subjective assessment of patients.

OBJECTIVES

To develop and perform an initial pilot validation of a new easy-to-use quantitative tool for assessing AK severity on the head.

METHODS

The actinic keratosis area and severity index (AKASI) for the head was developed based on a review of other severity scoring systems in dermatology, in particular the psoriasis area and severity index (PASI). Initial validation was performed by 13 physicians assessing AK severity in 18 AK patients and two controls using a physician global assessment (PGA) and AKASI. To determine an AKASI score, the head was divided into four regions (scalp, forehead, left/right cheek ear, chin and nose). In each region, the percentage of the area affected by AKs was estimated, and the severities of three clinical signs of AK were assessed: distribution, erythema and thickness.

RESULTS

There was a strong correlation between AKASI and PGA scores (Pearson correlation coefficient: 0.86). AKASI was able to discriminate between different PGA categories: mean (SD) AKASI increased from 2.88 (1.18) for 'light' to 5.33 (1.48) for 'moderate', 8.28 (1.89) for 'severe', and 8.73 (3.03) for 'very severe' PGA classification. The coefficient of variation for AKASI scores was low and relatively constant across all PGA categories.

CONCLUSIONS

Actinic keratosis area and severity index is proposed as a new quantitative tool for assessing AK severity on the head. It may be useful in the future evaluation of new AK treatments in clinical studies and the management of AK in daily practice.

Oral Terbinafine in the Treatment of Multi-Site Seborrheic Dermatitis: A Multicenter, Double-Blind Placebo-Controlled Study

Seborrheic dermatitis (SD) is a common disorder for which no satisfactory curative treatment exists. Preliminary studies suggest that terbinafine may be effective. The efficacy and tolerability of oral terbinafine was evaluated in multi-site SD in a randomized, double-blind, placebo-controlled study. For this purpose, 174 adult patients with SD lesions involving ≥3 skin areas, each causing ≥2 moderate/severe symptoms according to a pre-defined clinical score, were classified according to the localization of lesions: patients with lesions predominantly involving non-exposed skin areas, such as scalp and hairline and sternum and/or interscapular area (Population A, n=83) or patients with lesions in exposed sites, mainly the face (Population B, n=91). Patients were randomized to oral terbinafine (250 mg/day) (n=86) or matching placebo (n=88), each given for 6 weeks. Primary efficacy variable was the response rate, defined as ≥50% decrease in baseline total clinical score without rescue medication intake after 6 weeks of treatment. The main secondary assessments were: subject's global assessment of relief and proportion of patients satisfied with treatment. Recurrence rate was assessed in responder patients during a 4-week treatment-free period. In Population A the response rate after 6 weeks of treatment was significantly higher with terbinafine (70% vs 45.4%; p=0.03) and so was the proportion of patients who reported relief (75% vs 41%; p=0.007) and who were satisfied (66% vs 40%; p=0.02). No significant differences were recorded in Population B. Adverse events occurred in 11.5% of terbinafine patients and 8% of placebo patients. One patient discontinued treatment with terbinafine because of adverse events (mild tachycardia and insomnia). In conclusion, our results show that terbinafine is significantly more effective than placebo in reducing the severity of SD lesions in non-exposed sites. Clinical trials comparing terbinafine to standard treatment regimens in different types of patients with SD are warranted.

Reflectance confocal microscopy in the diagnosis of vesicobullous disorders: case series with pathologic and cytologic correlation and literature review

BACKGROUND

Vesicobullous disorders are characterized by intraepidermal or subepidermal blistering resulting from different pathogenetic mechanisms. The diagnosis is generally based on clinical examination and semi-invasive/invasive procedures such as cytology and histopathology. In vivo reflectance confocal microscopy (RCM) is a non-invasive technique for real-time, en face imaging of the epidermis and upper dermis with high resolution close to conventional histopathology.

PURPOSE

To evaluate RCM features of different vesicobullous diseases and correlate with cytologic and histopathologic examination.

METHODS

Ten patients (6M/4F, age range: 9-81 years) affected by blistering diseases, such as herpes simplex, herpes zoster, Kaposi's varicelliform eruption, pemphigus vulgaris, Hailey-Hailey disease, bullous pemphigoid, and porphyria cutanea tarda were evaluated using a handheld RCM device.

RESULTS

In our study, a clear correlation between RCM and Tzanck's test and/or histopathology was observed. RCM allowed in all cases an easy identification of the blister spaces and of the split levels, and in some cases specific features were detected, such as giant keratinocytes in herpes infections and acantholytic cells in pemphigus vulgaris and Hailey-Hailey disease.

CONCLUSION

Reflectance confocal microscopy may support the clinical diagnosis of vesicobullous disorders and indicate to the physician the appropriate patient management and/or the need for further investigation.

Bacterial chemotaxis: information processing, thermodynamics, and behavior

Escherichia coli has long been used as a model organism due to the extensive experimental characterization of its pathways and molecular components. Take chemotaxis as an example, which allows bacteria to sense and swim in response to chemicals, such as nutrients and toxins. Many of the pathway's remarkable sensing and signaling properties are now concisely summarized in terms of design (or engineering) principles. More recently, new approaches from information theory and stochastic thermodynamics have begun to address how pathways process environmental stimuli and what the limiting factors are. However, to fully capitalize on these theoretical advances, a closer connection with single-cell experiments will be required.