Epidermal growth factor as a biologic switch in hair growth cycle

The hair growth cycle consists of three stages known as the anagen (growing), catagen (involution), and telogen (resting) phases. This cyclical growth of hair is regulated by a diversity of growth factors. Although normal expression of both epidermal growth factor and its receptor (EGFR) in the outer root sheath is down-regulated with the completion of follicular growth, here we show that continuous expression of epidermal growth factor in hair follicles of transgenic mice arrested follicular development at the final stage of morphogenesis. Data from immunoprecipitation and immunoblotting showed that epidermal growth factor signals through EGFR/ErbB2 heterodimers in skin. Furthermore, topical application of tyrphostin AG1478 or AG825, specific inhibitors of EGFR and ErbB2, respectively, completely inhibited new hair growth in wild type mice but not in transgenic mice. When the transgenic mice were crossed with waved-2 mice, which possess a lower kinase activity of EGFR, the hair phenotype was rescued in the offspring. Taken together, these data suggest that EGFR signaling is indispensable for the initiation of hair growth. On the other hand, continuous expression of epidermal growth factor prevents entry into the catagen phase. We propose that epidermal growth factor functions as a biologic switch that is turned on and off in hair follicles at the beginning and end of the anagen phase of the hair cycle, guarding the entry to and exit from the anagen phase.postprin

Demonstration of syringe-pump-induced disturbance in microfluidic system with low interfacial tension

Talk #21Junior Scientist, Postdoc and Student WorkshopsSyringe pump provides precise and constant flow rates so it is widely used in microfluidic research and applications. Most syringe pumps are mechanically driven and introduce fluctuations or pulses to the inlet flow and thus affect the steadiness of the flow. However, to the best of our knowledge, no evidences confirmed that these are really induced by syringe pumps. Here we introduce a robust visual detection of the unsteadiness induced by the stepping motor in a syringe pump, in form of ripples on the interface of an aqueous two-phase system which has low interfacial tension. We use a typical glass capillary device to generate a co-flow of two immiscible phases in our experiments [1]. The ripples are found to exhibit the same frequency as that delivered by the stepping motor of the syringe pump which drives the inner fluid, named as fpump, for various flow rates Q, syringe diameters D and advancing step sizes s, according to fpump = 4Q/(πD2s). The experimental results suggest that the low interfacial tension system can reflect the disturbance aroused from the inner pump, thus give an insight into understanding the fluctuation that syringe pumps induces and provide a way to test whether the unsteadiness in microfluidic system is related to syringe pump or not.published_or_final_versio

The transformation dynamics towards equilibrium in non-equilibrium w/w/o double emulsions

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The dripping-to-jetting transition in a co-axial flow of aqueous two-phase systems with low interfacial tension

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Perturbation-induced droplets for manipulating droplet structure and configuration in microfluidics

In this work, we mechanically perturb a liquid-in-liquid jet to manipulate the size and structure of the droplets formed from break-up of the jet. The induced break-up is relatively insensitive to fluctuations in the surrounding fluid flow. When the amplitude of perturbations is large and the interfacial tension of the liquid–liquid system is low, the size of the droplets can be precisely tuned by controlling the rate at which the liquid exits the tip of the dispensing nozzle through the frequency of perturbation. When applied to microfluidic devices with the appropriate geometry, our perturbation-induced droplet approach offers a strategy to manipulating droplet structures. We demonstrate that by varying the imposed perturbation frequency and phase lag, the structure of the multi-compartmental drops and the configuration of the resultant drops in the same flow condition can be manipulated. Moreover, after careful treatment of the wettability of the devices, we show that the structure of the droplets can be precisely controlled to change from single emulsion to double emulsion within the same device. The perturbation-induced droplet generation represents a new paradigm in the engineering of droplets, enhancing current droplet-based technologies for applications ranging from particle fabrication to confined micro-reactions.postprin

Musical Interfaces: Visualization and Reconstruction of Music with a Microfluidic Two-Phase Flow

Detection of sound wave in fluids can hardly be realized because of the lack of approaches to visualize the very minute sound-induced fluid motion. In this paper, we demonstrate the first direct visualization of music in the form of ripples at a microfluidic aqueous-aqueous interface with an ultra-low interfacial tension. The interfaces respond to sound of different frequency and amplitude robustly with sufficiently precise time resolution for the recording of musical notes and even subsequent reconstruction with high fidelity. Our work shows the possibility of sensing and transmitting vibrations as tiny as those induced by sound. This robust control of the interfacial dynamics enables a platform for investigating the mechanical properties of microstructures and for studying frequency-dependent phenomena, for example, in biological systems.published_or_final_versio

Lifestyle and socioeconomic correlates of breakfast skipping in Hong Kong primary 4 schoolchildren

Objective: Although breakfast is associated with different benefits, breakfast skipping is increasingly common among children. This study aimed to identify lifestyle and socioeconomic correlates of breakfast skipping in Hong Kong schoolchildren. Methods: 68 606 primary 4 participants of the Department of Health Student Health Service in 1998-2000 reported breakfast habit and other lifestyle characteristics using a standardized questionnaire. Height and weight were measured by trained SHS nurses. Socioeconomic data were reported by parents. In cross-sectional analysis, multivariate logistic regression was used to identify lifestyle and socioeconomic correlates of breakfast skipping. Results: 3 598 subjects (5.2%) usually skipped breakfast. Breakfast skipping was associated with being overweight (Odds ratio = 1.59, 95% CI: 1.46 to 1.73) and obese (2.06, 1.80 to 2.36), and unhealthy dietary habits including more frequent junk food (1.23, 1.14 to 1.33) but less frequent fruit/vegetable (1.23, 1.13 to 1.34) and milk (1.98, 1.80 to 2.16) intake. Breakfast skippers tended to skip lunch, do less extra-curricular physical activity, watch more television and have less educated parents. Conclusions: Breakfast skipping was significantly related to various health-compromising lifestyle characteristics and lower parental education. Breakfast habit can be a potential lifestyle indicator. Education programmes aimed at specific target groups should encourage regular breakfast consumption. © 2010 Elsevier Inc.postprin

Exposure to particulate air pollution at different living locations and respiratory symptoms in Hong Kong-an application of satellite information

Respiratory ill-health effects due to particulate air exposure at different geographical locations in Hong Kong that aggregate individual living locations were estimated based on satellite information. We assessed the presence of respiratory symptoms of a frequent cough or sputum in school students aged 11-20 years old (n=9,881). Daily particulate air pollution levels at students' living locations were derived from the surface extinction coefficients measured by satellite and measurements from the air pollutant monitoring stations at ground level. Adjusted odds ratio (OR) [95% CI] of respiratory symptoms was 1.047 [1.005, 1.091] per 10 g m-3 increase in PM10 concentration. Specificity tests showed that adjusted OR of having other symptoms is not significant (p=0.20-0.94). Exposures to PM10 at different geographical locations is associated with increased odds of having respiratory symptoms (cough or sputum) but not with other symptoms unrelated to air pollution. © 2010 Taylor & Francis.postprin

Speaker verification with a priori threshold determination using kernel-based probabilistic neural networks

Department of Electronic and Information EngineeringRefereed conference pape

Biomechanical assessment of below-knee residual limb tissue

Version of RecordPublishe