Prospective Randomized Controlled Trial on the Effects of Almonds on Facial Wrinkles and Pigmentation.

BACKGROUND: Almonds have long been studied as a rich source of fatty acids, phytochemical polyphenols and antioxidants such as vitamin E. A recent study compared almond supplementations to a calorie-matched intervention for 16 weeks, yielding statistically significant improvement in wrinkle severity in postmenopausal women with Fitzpatrick skin types I and II that received almonds. This study furthers that assessment with a larger population and duration of 24 weeks to assess the influence of almond consumption on wrinkle severity, skin pigmentation and other skin biophysical profiles. OBJECTIVE: To investigate the effects of almond consumption on photoaging such as wrinkles and pigment intensity as well as facial biophysical parameters such as sebum production, skin hydration and water loss. DESIGN AND INTERVENTIONS: A prospective, randomized controlled study assessed postmenopausal women with Fitzpatrick skin types I or II who consumed 20% of their daily energy consumption in either almonds or a calorie-matched snack for 24 weeks. A facial photograph and image analysis system was used to obtain standardized high-resolution photographs and information on wrinkle width and severity at 0, 8, 16 and 24 weeks. Measurements of transepidermal water loss (TEWL), skin pigmentation, skin hydration and sebum production were also completed at each visit. RESULTS: The average wrinkle severity was significantly decreased in the almond intervention group at week 16 and week 24 compared to baseline by 15% and 16%, respectively. Facial pigment intensity was decreased 20% in the almond group at week 16 and this was maintained by week 24. There were no significant differences in skin hydration or TEWL in the almond group compared to the control, although sebum excretion was increased in the control group. CONCLUSION: The daily consumption of almonds may improve several aspects of photoaging such as facial wrinkles and pigment intensity in postmenopausal women. In conclusion, the daily consumption of almonds may contribute to the improvement of facial wrinkles and reduction of skin pigmentation among postmenopausal women with Fitzpatrick skin types I and II.

Efficacy of microneedling versus fractional Er:YAG laser in facial rejuvenation.

BACKGROUND: Microneedling and fractional lasers have been used in facial rejuvenation with acceptable results and low adverse effects. AIMS: To compare the efficacy of microneedling with fractional Er:YAG in facial skin rejuvenation. PATIENTS/METHODS: This study was planned as a split-face clinical trial. Volunteers were randomly allocated to receive three monthly treatments on each side of the face, one with fractional Er:YAG laser and one with microneedling. The assessments included investigating clinical outcomes by two blinded dermatologists accompanied by measuring skin biophysical characteristics including cutaneous resonance running time (CRRT) and transepidermal water loss (TEWL). Moreover, possible adverse effects, downtime, and patients' satisfaction were recorded at baseline, 1 month after each treatment, and 3 months after the last treatment session. The protocol was approved by the Iranian Registry of Clinical Trials (IRCT20160820029436N3). RESULTS: Of the 32 selected volunteers, 24 subjects completed the study. The clinical assessment showed a significant improvement of the face appearance along with a significant reduction in dyschromia, and periorbital wrinkling (P-value < .05), with both procedures without any considerable difference between two methods. Moreover, the patients showed substantial satisfaction with both modalities with no statistically significant difference. Mean TEWL and CRRT values also decreased significantly in both groups with no considerable difference. The downtime was significantly shorter in the microneedling-treated side. There were no long-lasting or severe adverse effects after treatment with both methods. CONCLUSION: Microneedling and fractional Er:YAG laser have comparable efficacy in facial rejuvenation, but little downtime of the former makes it preferable for many patients.

Indicators of skin barrier integrity among newborns massaged with mustard oil in rural Nepal.

OBJECTIVE: The objective of this study was to determine the skin barrier changes during postnatal month 1 among infants receiving routine mustard oil massage in the humid conditions of rural Nepal. STUDY DESIGN: This was an observational study among 500 live-born neonates receiving mustard oil massage. Skin integrity such as erythema, rash, dryness, skin pH, stratum corneum protein concentration and transepidermal water loss was measured on days 1, 3, 7, 14 and 28. RESULTS: Erythema and rash increased (worsened) during weeks 1 and 2, then decreased over weeks 3 and 4. Skin pH (6.1±0.5 to 5.0±0.6) and stratum corneum protein (16.6±7.9 to 13.5±5.9 µg cm-2) decreased. Transepidermal water loss increased from 33.2±23.5 to 43.0±24.5 g m-2 h-1 at day 28. Skin pH and stratum corneum protein were higher for early versus late premature infants. CONCLUSION: Premature and full-term skin condition was generally poor especially during the first 2 weeks, improving thereafter. Maturational changes were evident.

Transepidermal Water Loss in Neonates: Baseline Values Using a Closed-Chamber System.

BACKGROUND: Transepidermal water loss (TEWL) is the normal, constitutive loss of water vapor from the skin in the absence of sweat gland activity. It is regarded as one of the most important parameters for characterizing skin barrier function, and the values are dependent on multiple variables. The objective of this study was to evaluate TEWL in neonates using a closed- chamber system, and determine if there is a variation of TEWL with the mode of delivery, pre-term birth, low birthweight or phototherapy. METHODS: This prospective study was conducted in 104 healthy neonates, 30 neonates in the Neonatal Intensive Care Unit (NICU) and 40 adults using a noninvasive, closed- chamber system (VapoMeter™). RESULTS: A statistically significant difference in TEWL was noted between newborns and adults. No remarkable difference in TEWL was seen between boys or men and girls or women or those born via normal vaginal birth and caesarean section, but TEWL was significantly higher in preterm and low birthweight neonates. Significantly higher TEWL was noted from the antecubital fossa of the neonates who received phototherapy when compared with six other sites. CONCLUSIONS: The closed- chamber system is an acceptable alternative to the more widely used open-chamber system. The higher mean TEWL in neonates suggests that the epidermal barrier is still adapting to extrauterine life, making newborn skin more sensitive and requiring appropriate, age adapted care.

Dairy and nondairy beverage consumption for childhood atopic eczema: what health advice to give?

BACKGROUND: Many parents of children with atopic eczema (AE) practise empirical dietary avoidance and supplementation, and seek healthcare advice on whether consumption of dairy and nondairy beverages may be beneficial or detrimental for this condition. AIM: We investigated if frequency of consumption of beverages was associated with disease severity and quality of life (QoL). METHODS: Parent-reported frequency of drinks and beverages were recorded in consecutive children with AE, and disease severity (Nottingham Eczema Severity Score; NESS), QoL (Children's Dermatology Life Quality Index; CDLQI), skin hydration (SH), transepidermal water loss (TEWL), blood pressure (BP), resting heart rate (RHR) and body mass index (BMI) were evaluated. RESULTS: AE was associated with worse QoL than miscellaneous non-AE skin diseases (P < 0.001). Compared with children without AE, there was a trend for children with AE to drink less milk (P = 0.06) and more miscellaneous beverages (such as Chinese herbal tea and soymilk; P = 0.03). In children with AE, NESS correlated with CDLQI (ρ = 0.66, P < 0.001) and reduced SH (ρ = -0.32, P < 0.001), whereas CDLQI correlated with a higher RHR (ρ = 0.25, P < 0.01). Multiple logistic regression showed that male sex (OR = 0.44, 95% CI 0.20-0.97; P = 0.04) and drinking fresh milk (OR = 0.42, 95% CI 0.20-0.93; P = 0.03) were independent factors associated with less severe disease. Moderate to severe impairment of CDLQI was associated with NESS (OR = 1.48, 95% CI 1.28-1.71; P < 0.001) and RHR (OR = 1.05, 95% CI 1.02-1.08; P < 0.01) but not with reported habits of beverage consumption. Concerning cardiovascular health in AE, frequency of formula milk consumption was associated with RHR (ρ = 0.17, P = 0.04), and soft drink consumption was associated with higher systolic blood pressure (SBP) (ρ = 0.18, P = 0.04). CONCLUSION: This study provides evidence for parental/patient guidance. Children with AE who reported more fresh milk consumption had less severe disease. There was no correlation between consumption of nondairy beverages with disease severity or QoL, but frequency of soft drink consumption correlated with SBP. With these results being supported by a literature review, it is reasonable to advise parents that fresh milk can be consumed by unsensitized children with AE. Soft drinks and other beverages should not be consumed in excess for optimal cardiovascular health and for other health reasons.

Analysis of the temporal change in biophysical parameters after fractional laser treatments using reflectance confocal microscopy.

BACKGROUND: Fractional photothermolysis is a popular treatment option for photorejuvenation. Previous literature studies have demonstrated the clinical effectiveness of fractional photothermolysis on cutaneous photoaging; however, the associated changes in biophysical properties of the skin following fractional photothermolysis have not been fully elucidated. This study was conducted to investigate the temporal changes in biophysical parameters after fractional laser treatment on Asian skin. MATERIALS AND METHODS: Eleven female subjects underwent a single treatment with an erbium glass fractional laser. Skin roughness, elasticity, transepidermal water loss (TEWL), dermal thickness were evaluated before and immediately after treatment and 3 days, 1 week, 2 weeks, and 4 weeks after treatment. The changes in the dermal papilla were analyzed using a reflectance confocal microscopy (RCM). RESULTS: Skin roughness showed the greatest improvement at the first week and net elasticity was most improved at the second week. TEWL and the percentage of melanized and active dermal papillae (DP) were mostly increased for 3 days. At 4 weeks after treatment, the number of total dermal papillae showed a significant increase compared with pretreatment. CONCLUSION: This is the first study of the characterization and quantification of dermal papilla reflecting the dermal repair process after fractional photothermolysis through an RCM.

Clinical efficacy of facial masks containing yoghurt and Opuntia humifusa Raf. (F-YOP).

Facial packs or masks are popular beauty treatments that are thought to improve skin quality. We formulated a yoghurt pack using natural ingredients (F-YOP), with consideration of skin affinity, safety, health, and beauty. Then, we performed an in vitro assessment of biological activity and in vivo assessments of moisture, TEWL, melanin content, and elasticity. Facial areas treated with F-YOP showed increased moisture compared to control regions: 89±6.26% (forehead), 140.72±10.19% (cheek), and 123.29±6.67% (chin). Transepidermal water loss (TEWL) values were decreased in the treated areas compared to control: 101.38±6.95% (forehead), 50.37±5.93% (cheek), and l57.81±10.88% (chin). Elasticity was decreased in the control region, whereas the treatment region did not change. The initial elasticity was maintained in the cheek. F-YOP exhibited activity on DPPH radical scavenging, SOD-like activity, and lipoxygenase activity. F-YOP treatment successfully improved the moisture, brightness, and elasticity of treated skin.

Modification of the conformational skin structure by treatment with liposomal formulations and its correlation to the penetration depth of aciclovir.

The stratum corneum (SC), top layer of the epidermis, is comprised mostly of lipids that are responsible for the permeability properties of the SC and which protect the body from external agents. Changes in these skin microconstituents can be understood by instrumental methods such as attenuated total reflectance Fourier-transform infrared (ATR-FTIR) spectroscopy. The present work shows that different types of analyzed skin, dermatomed abdominal porcine skin, pig ear skin, and human heat separated skin, influenced both the shape and the intensity of recorded spectra. The typical FTIR spectral bands of the conformation of the lipid aliphatic chains in the skin samples were altered after treatment with pure DPPC liposomes and chitosan (CS) coated DPPC liposomes, but not with aqueous CS-solution. The conformational change could be the reason for the variable permeability of the skin. This was confirmed by tape stripping on pig ear skin (imitating in vivo studies): the amount of aciclovir penetrating from polymer coated and polymer free liposomes was significantly higher under the skin surface in comparison with the aqueous CS-solution. Moreover, the addition of the polymer to liposomes induced a higher skin penetration than pure liposomes. One explanation might be the CS's stronger adhesion to the skin.

Reduced hyperthermia-induced cutaneous vasodilation and enhanced exercise-induced plasma water loss at simulated high altitude (3,200 m) in humans.

We examined whether less convective heat loss during exercise at high altitude than at sea level was partially caused by reduced cutaneous vasodilation due to enhanced plasma water loss into contracting muscles and whether it was caused by hypoxia rather than by hypobaria. Seven young men performed cycling exercise for 40 min at 50% peak aerobic power in normoxia at (710 mmHg) 610 m, determined before the experiments, in three trials: 1) normobaric normoxia at 610 m (CNT), 2) hypobaric hypoxia [low pressure and low oxygen (LPLO)] at 3,200 m (510 mmHg), 3) normobaric hypoxia [normal pressure and low oxygen (NPLO)] at 610 m, in an artificial climate chamber where atmospheric temperature and relative humidity were maintained at 30°C and 50%, respectively. Subjects in CNT and LPLO breathed room air, whereas those in NPLO breathed a mixed gas of 14% O2 balanced N2, equivalent to the gas composition in LPLO. We measured change in PV (ΔPV), oxygen consumption rate (Vo2), mean arterial blood pressure (MBP), esophageal temperature (T(es)), mean skin temperature (T(sk)), forearm skin blood flow (FBF), and sweat rate (SR) during exercise. Although Vo2, MBP, T(sk), and SR responses during exercise were similar between trials (P > 0.05), the sensitivity of forearm vascular conductance (FBF/MBP) in response to increased T(es) was lower in LPLO and NPLO than in CNT (P < 0.05), whereas that of SR was not, resulting in a greater increase in T(es) from minute 5 to 40 of exercise in LPLO and NPLO than in CNT (P = 0.026 and P = 0.011, respectively). ΔPV during exercise was twofold greater in LPLO and NPLO than in CNT. These variables were not significantly different between LPLO and NPLO. Thus reduced convective heat loss during exercise at 3,200 m was partially caused by reduced cutaneous vasodilation due to enhanced PV loss. Moreover, this may be caused by hypoxia rather than by hypobaria.

Sudomotor dysfunction in patients with optic neuritis.

OBJECTIVES: Optic neuritis (ON) is a frequent initial manifestation of multiple sclerosis (MS). Autonomic failure affecting the pupillary function is known to exist in ON patients, and patients with MS are known to have more widespread autonomic dysfunction. For example, sudomotor dysfunction is well known in MS. We carried out a study investigating sudomotor abnormalities in ON patients, and later followed these patients at risk of developing MS. METHODS: Firstly, sudomotor function was measured by sympathetic skin responses (SSRs) in 13 ON patients and in 22 healthy controls. Secondly, thermoregulatory sweating was measured by an evaporimeter after a heating stimulus in 13 ON patients and in 14 healthy control subjects. RESULTS: The SSR latencies to electrical stimuli in the ON patients were significantly prolonged in the upper and lower extremities (p = 0.013-0.002), indicating sudomotor dysfunction. No statistically significant thermoregulatory sweating dysfunction could be found in the ON patients compared to the controls. All ON patients underwent a follow-up (mean duration 12.5 years) during which eight ON patients (62%) converted to clinically definite MS. It seemed that SSRs had no value for identifying patients who later developed MS. INTERPRETATION: Our results enlarge the knowledge of autonomic disorders in ON patients, showing that sudomotor function may also be involved.

Stress, inflammation, and yoga practice.

OBJECTIVE: To address the mechanisms underlying hatha yoga's potential stress-reduction benefits, we compared inflammatory and endocrine responses of novice and expert yoga practitioners before, during, and after a restorative hatha yoga session, as well as in two control conditions. Stressors before each of the three conditions provided data on the extent to which yoga speeded an individual's physiological recovery. METHODS: A total of 50 healthy women (mean age, 41.32 years; range, 30-65 years), 25 novices and 25 experts, were exposed to each of the conditions (yoga, movement control, and passive-video control) during three separate visits. RESULTS: The yoga session boosted participants' positive affect compared with the control conditions, but no overall differences in inflammatory or endocrine responses were unique to the yoga session. Importantly, even though novices and experts did not differ on key dimensions, including age, abdominal adiposity, and cardiorespiratory fitness, novices' serum interleukin (IL)-6 levels were 41% higher than those of experts across sessions, and the odds of a novice having detectable C-reactive protein (CRP) were 4.75 times as high as that of an expert. Differences in stress responses between experts and novices provided one plausible mechanism for their divergent serum IL-6 data; experts produced less lipopolysaccharide-stimulated IL-6 in response to the stressor than novices, and IL-6 promotes CRP production. CONCLUSION: The ability to minimize inflammatory responses to stressful encounters influences the burden that stressors place on an individual. If yoga dampens or limits stress-related changes, then regular practice could have substantial health benefits.

Specific gel-cream as adjuvant to oral isotretinoin improved hydration and prevented TEWL increase--a double-blind, randomized, placebo-controlled study.

BACKGROUND: Hydrating and emollient products are often recommended to patients under isotretinoin therapy to control the most frequent mucocutaneous side effects and to improve adherence to treatment. AIMS: To assess, using noninvasive biophysical tests, the clinical and instrumental effectiveness of a hydrating gel-cream compared with placebo as an adjuvant to isotretinoin for treatment of facial skin in patients with inflammatory acne. METHODS: Prospective, double-blind, randomized study, using MULTI SKIN MC750, on the adjuvant effect of a hydrating gel-cream for acne (active product) vs. a gel-cream without active substances (placebo). Follow-up lasted 3 months. RESULTS: Sixty-six patients were included. Thirty-four were administered the active product, and 32 placebo. Though the number of lesions fell significantly in both groups, the mean number of papules on day 30 was significantly lower in the active product group. The active product group showed a significant increase in hydration, while the placebo group showed a significant increase in transepidermal water loss (TEWL). Seborrhoea decreased significantly in both groups; there were no differences between them. CONCLUSIONS: Compared with placebo, the specific gel-cream with active products as an adjuvant to oral isotretinoin improved hydration, prevented TEWL increase, and reduced inflammatory acne lesions after 30 days.

Psychological stress and wound healing in humans: a systematic review and meta-analysis.

OBJECTIVE: The current review aims to synthesize existing knowledge about the relationship between psychological stress and wound healing. METHODS: A systematic search strategy was conducted using electronic databases to search for published articles up to the end of October 2007. The reference lists of retrieved articles were inspected for further studies and citation searches were conducted. In addition, a meta-analysis of a subset of studies was conducted to provide a quantitative estimation of the influence of stress on wound healing. RESULTS: Twenty-two papers met the inclusion criteria of the systematic review and a subsample of 11 was included in a meta-analysis. The studies assessed the impact of stress on the healing of a variety of wound types in different contexts, including acute and chronic clinical wounds, experimentally created punch biopsy and blister wounds, and minor damage to the skin caused by tape stripping. Seventeen studies in the systematic review reported that stress was associated with impaired healing or dysregulation of a biomarker related to wound healing. The relationship between stress and wound healing estimated by the meta-analysis was r=-0.42 (95% CI=-0.51 to -0.32) (P<.01). CONCLUSION: Attention now needs to be directed towards investigating potential moderators of the relationship, mediating mechanisms underpinning the association, as well as the demonstration of a causal link by the development of experimental interventions in healthy populations.

Effects of oral epigallocatechin gallate supplementation on the minimal erythema dose and UV-induced skin damage.

BACKGROUND/AIMS: Excessive exposure to UV radiation causes acute adverse effects like sunburn and photosensitivity reactions and is involved in the induction and development of skin cancer. It has been reported that antioxidants have photoprotective effects against solar UV radiation. We investigated the effect of oral epigallocatechin gallate (EGCG), a powerful antioxidant in green tea, on the minimal erythema dose (MED) and UV-induced skin damage. METHOD: Female HWY/Slc hairless rats were fed the normal diet supplemented with 1,500 ppm EGCG for 8 weeks; then, the MED was determined and visual scores and transepidermal water loss were assessed to evaluate the severity of UV-induced skin damage. RESULTS: At week 8 of the study, the use of dietary EGCG significantly increased MED. UV-radiation-induced sunburn severity and alterations in epidermal barrier function were also attenuated by the supplementation of EGCG. CONCLUSION: Regular intake of EGCG strengthens the skin's tolerance by increasing MED and thus prevents UV-induced perturbation of epidermal barrier function and skin damage. These results suggest that EGCG is a potent candidate for systemic photoprotection.

Cosmetic formulations containing Lithospermum erythrorhizon root extract show moisturizing effects on human skin.

Retention of water in the stratum corneum of skin epidermis plays an important role in regulation of skin function. Loss of water may decline skin appearance gradually and lead to irregular skin disorders. The root extract of Lithospermum erythrorhizon (LES) is known for its various pharmacological activities. However, the potential skin care effect of LES is not clear. The aim of this study was to evaluate the moisturizing efficacy and skin barrier repairing activity of LES. For this study, 30 healthy Asian females (age 20-30) with healthy skin had applied the test emulsions twice daily over a period of 28 days. The skin properties were measured by skin bioengineering techniques. Our preliminary results indicated that LES show moisturizing effect on skin hydration in a time- and dose-dependent pattern, and the maximum increase in skin humidity was 11.77 +/- 1.18% for emulsion LES5.00. Particularly, LES-containing emulsions significantly improve skin barrier function by decreasing the value of transepidermal water loss (TEWL) in a time- and dose-dependent pattern, and the maximum decrease in TEWL value was 7.68 +/- 0.79% for emulsion LES5.00. Taken together, our data demonstrate that LES is more effective in increasing skin humidity and decreasing the TEWL values, indicating the potential skin care effects of LES.

Nocturnal itch: why do we itch at night?

Pruritus is exacerbated at night in many systemic and dermatological diseases, resulting in reports of significantly diminished quality of life and sleep disturbances. At present, the underlying mechanisms responsible for night-time itching are not well understood. Nocturnal pruritus may be related to the circadian rhythm of itch mediators and possibly the disruption of such patterns. Diurnal changes in skin physiology, such as temperature and barrier function, may also play a role. Currently, the paucity of specific treatment options for nocturnal pruritus is alarming and needs to be addressed by future research. This review describes the scale of the problem associated with nocturnal pruritus, the impact it has on patients, possible underlying mechanisms and, lastly, treatment options.

Comparison of biophysical properties of skin measured by using non-invasive techniques in the KM mice following 595 nm pulsed dye, 1064 nm Q-Switched Nd:YAG and 1320 nm Nd:YAG laser non-ablative rejuvenation.

BACKGROUNDS/AIMS: The aim of the study was to compare the changes of the biophysical properties and to objectify the effects of 595 nm pulsed dye, 1064 nm Q-switched Nd:YAG and 1320 nm Nd:YAG lasers non-ablative rejuvenation by non-invasive techniques. METHODS: KM mice were used for the study. The 595 nm pulsed dye, 1064 nm Q-switched Nd:YAG and 1320 nm Nd:YAG laser treatments were evaluated with biophysical parameter measurements including skin elasticity, skin color, skin trans-epidermal water loss (TEWL) and skin hydration. RESULTS: All three lasers improved the biophysical properties in the skin of KM mice. In skin elasticity measurements, the 1064 nm laser treatment showed the lowest ratio (0.61+/-0.09) while the 1320 nm laser showed the highest one (0.76+/-0.07) on day 60. For erythema values, a significant increase was observed immediately after the 1064 nm laser treatment (196.67+/-19.17), but the lowest values occurred with the 1320 nm laser treatment (189.83+/-16.54). None of the three lasers resulted in obvious changes of skin melanin. TEWL increased immediately after laser irradiation, then began to recover and decreased 60 days after the 595 and 1064 nm laser treatments. With the 1320 nm laser treatment the TEWL began to decrease from day 7 and obtained the lowest mean values (5.23+/-1.13). The water-holding capacity increased initially for the 595 and 1320 nm laser irradiation, while decreased for the 1064 nm laser. At day 60 of the experiment, skin hydration values in all animals were superior to those of the controls. The 1320 nm laser treatment caused the highest ratio (1.29+/-0.26). Both the values of TEWL and skin hydration for the 1320 nm laser treated areas differed significantly from the other two lasers. CONCLUSIONS: Our data showed the 1064 nm Q-switched Nd:YAG laser treatment was most effective in improving the skins' mechanical properties, while the 1320 nm Nd:YAG laser can enhance greatly the skin barrier function and the water-holding capacity. Moreover, we demonstrated the biophysical properties differed considerably between different areas.

Plant senescence cues entry into diapause in the gall fly Eurosta solidaginis: resulting metabolic depression is critical for water conservation.

Mechanisms and possible cues for seasonal increases in desiccation resistance in larvae of the goldenrod gall fly Eurosta solidaginis, were examined before and after natural and premature plant senescence, or after being removed from their gall and placed in either 100, 95 or 75% relative humidity (RH). Rates of water loss were 8.6-fold lower, averaging 0.7+/-0.2 microg mm(-2) h(-1), in larvae from senescent gall tissue and after all RH treatments than in control larvae from pre-senescent plants. Enhanced desiccation resistance occurred quickly, within 3 days of removal from their gall. Contrary to most previous reports, a large majority of the increased desiccation resistance (approximately 85%) was due to reduced respiratory transpiration with the remainder being the result of a lowered cuticular permeability. Rates of cuticular water loss were reduced by the presence of a vapor pressure gradient between the larval hemolymph and environmental water vapor and were probably due to increases in cuticular lipids and/or production of the cryoprotectant glycerol. Metabolic rate was reduced by over fourfold, averaging 0.07+/-0.01 microl CO2 g(-1) h(-1), in larvae from senescent gall tissue and all RH treatments compared to larvae from pre-senescent plants. The magnitude of the reduction in metabolic rates indicated that these larvae had entered diapause. In addition, larvae entered diapause in response to removal from, or degeneration of, the gall tissue they feed, on rather than seasonal changes in temperature or photoperiod. The low metabolic rates of the diapausing larvae probably allowed them to dramatically reduce their respiratory transpiration and total rate of water loss compared with non-diapausing controls. Thus, diapause, with its associated lowered metabolic rate, may be essential for conserving water in overwintering temperate insects, which may be dormant for six or more months of the year.

Three-dimensional model on thermal response of skin subject to laser heating.

A three-dimensional (3D) multilayer model based on the skin physical structure is developed to investigate the transient thermal response of human skin subject to laser heating. The temperature distribution of the skin is modeled by the bioheat transfer equation, and the influence of laser heating is expressed as a source term where the strength of the source is a product of a Gaussian shaped incident irradiance, an exponentially shaped axial attenuation, and a time function. The water evaporation and diffusion is included in the model by adding two terms regarding the heat loss due to the evaporation and diffusion, where the rate of water evaporation is determined based on the theory of laminar boundary layer. Cryogen spray cooling (CSC) in laser therapy is studied, as well as its effect on the skin thermal response. The time-dependent equation is discretized using the finite difference method with the Crank-Nicholson scheme and the stability of the numerical method is analyzed. The large sparse linear system resulted from discretizing the governing partial differential equation is solved by a GMRES solver and the expected simulation results are obtained.