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.

Effects of conditioned media from human umbilical cord blood-derived mesenchymal stem cells in the skin immune response.

Atopic dermatitis (AD) is an inflammatory skin disease in which type 2 allergic inflammation plays a critical role. In this study, the anti-inflammatory effect of conditioned media from human umbilical cord blood-derived mesenchymal stem cells (USC-CM) was investigated in order to apply it as an effective treatment with a low risk of side effects that can overcome the limitations of AD treatment which is currently in use. We found that USC-CM has various growth factors and cytokines associated with anti-inflammatory effect. RT-PCR and ELISA analysis showed that USC-CM inhibited the levels of type 2 cytokine and chemokine Thymus and activation-regulated chemokine (TARC), TNF-α and IL-6 in TNF-α/IFN-γ-stimulated HaCaT cells. In addition, USC-CM inhibited IL-4 and IL-13 levels in Th2 cells. Therefore, the results of our study demonstrated that USC-CM has anti-inflammatory effect in TNF-α/IFN-γ-stimulated HaCaT cells which associated with the inhibition of the immunoglobulin (IgE) secretion by activating B cell line. Our In vivo results showed that when the USC-CM was applied to lesions of patients with the mild AD for 4 weeks, the skin barrier was strengthened by increasing the level of Corneometer and decreasing the value of transepidermal water loss (TEWL). In conclusion, the results suggest that USC-CM may have therapeutic effect for AD as cosmetics and drug materials.

The Role of Autophagy in Skin Fibroblasts, Keratinocytes, Melanocytes, and Epidermal Stem Cells.

Human skin acts as a barrier to protect our bodies from UV rays and external pathogens and to prevent water loss. Phenotypes of aging, or natural aging due to chronic damage, include wrinkles and the reduction of skin thickness that occur because of a loss of skin cell function. The dysregulation of autophagy, a lysosome-related degradation pathway, can lead to cell senescence, cancer, and various human diseases due to abnormal cellular homeostasis. Here, we discuss the roles and molecular mechanisms of autophagy involved in the anti-aging effects of autophagy and the relationship between autophagy and aging in skin cells.

Longitudinal progress of transepidermal water loss, color, and sensory elements in split-thickness skin graft donor sites in East Asians.

BACKGROUND: There is little research available that describes the natural progression of split-thickness skin graft (STSG) donor site wounds after re-epithelialization. The purpose of this study was to evaluate the longitudinal clinical progress of transepidermal water loss (TEWL), color, and sensory elements in STSG donor sites in East Asians. METHODS: Eighteen patients participated in this study. The TEWL, color, pressure threshold, and static two-point discrimination were evaluated from the center and upper lateral corner of the wounds and adjacent normal skin preoperatively and at 1, 2, 7, and 12 months postoperatively. RESULTS: The age was negatively correlated with preoperative values of TEWL (r = -0.49, P = 0.039). The elevated TEWL level from the STSG donor sites did not return to normal until 12 months after surgery. In the measurement of skin color, the elevated L* value normalized after 12 months following surgery, while the elevated a* and b* values persisted. In the sensory testing, there were no significant changes during the observation period except at 2 months postoperatively, representing a significant increase of pressure threshold in the periphery. CONCLUSIONS: In East Asians, elevated skin lightness level in STSG donor sites returned to normal at 12 months postoperatively, while the elevated TEWL and skin redness levels were improved but were not normalized at 12 months after surgery.

The impact of stress on epidermal barrier function: an evidence-based review.

BACKGROUND: The epidermal barrier functions to limit skin infection and inflammation by inhibiting irritant and immunogen invasion. Abundant evidence suggests that psychological stress stemming from crowding, isolation, nicotine smoking, insomnia, mental arithmetic tasks, physical pain, real-life stressors (examinations and marital strain) and lack of positive personality traits may impart both acute and chronic epidermal dysfunction. OBJECTIVES: To review the relationship between stress and epidermal barrier dysfunction. METHODS: A review of the PubMed and Embase databases was conducted to identify all English-language case-control, cross-sectional and randomized control trials that have reported the effect of stress on epidermal barrier function. The authors' conclusions are based on the available evidence from 21 studies that met the inclusion and exclusion criteria. RESULTS: Psychological stressors upregulate the hypothalamic-pituitary-adrenal axis to stimulate local and systemic stress hormone production. This ultimately leads to aberrant barrier dysfunction, characterized by decreased epidermal lipid and structural protein production, decreased stratum corneum hydration and increased transepidermal water loss. CONCLUSIONS: This evidence-based review explores the adverse effects of psychological stressors on epidermal barrier function. Future investigations using more real-life stressors are needed to elucidate further their impact on skin physiology and identify practical stress-relieving therapies that minimize and restore epidermal barrier dysfunction, particularly in at-risk populations. What's already known about this topic? The literature reports the negative effect of stress on prolonged wound healing. Less is known about the relationship between stress and epidermal barrier dysfunction, a chronic, superficial wound involving the upper epidermal layers. What does this study add? Psychological stressors impact epidermal barrier function by activating the hypothalamic-pituitary-adrenal axis to stimulate local and systemic stress hormone production. Stress hormones negatively affect the epidermal barrier by decreasing epidermal lipids and structural proteins, decreasing stratum corneum hydration and increasing transepidermal water loss. Identification of such stressors can promote stress-avoidance and stress-reduction behaviours that protect epidermal barrier function and prevent certain dermatological conditions.

Clinical Characteristics of Lower Extremity Surgical Site Infections in Dermatologic Surgery Based Upon 24-Month Retrospective Review.

Dermatologic surgery performed on the lower extremities has an increased risk for surgical site infections (SSI). Our objective was to evaluate the clinical characteristics associated with SSI following Mohs micrographic surgery (MMS) and wide local excisions (WLE) performed below the knee. We performed a single-center retrospective chart review of patients (n=271) that underwent these procedures. Within 14 days of the lower extremity procedure, four of 175 MMS patients (2.3%) developed SSI compared to eight of 96 WLE patients (8.3%; P=0.029). Subcuticular sutures and vertical mattress sutures as a group were associated with reduced 30-day infection rate when compared to other suture methods (P=0.006). Comparison of patients on prophylactic antibiotics to control patients without antibiotics did not reveal a statistically significant difference in infection rate. MMS infection rates trended lower as compared to WLE in the 14-day post-operative window. Doxycycline prophylaxis did not produce a statistically significantly lower rate of SSI, though results approached significance. A prospective study may be warranted to further compare cephalexin and doxycycline for dermatologic surgery below the knee. Subcuticular or vertical mattress sutures may be preferred when closing wounds due to their association with reduced infection rate. J Drugs Dermatol. 2018;17(7):766-771.

Suction blister lesions and epithelialization monitored by optical coherence tomography.

BACKGROUND/PURPOSE: Our objective was to assess epithelialization of suction blister lesions by optical coherence tomography (OCT) and benchmark it to histology using epidermal thickness (ET) as the primary outcome. METHODS: Thirty-two healthy volunteers were recruited to Study 1 and 2. One 10-mm suction blister was raised on each buttock, and the blister roof was excised. Lesions were covered with moisture-retaining dressing. In Study 1, the lesions were OCT-scanned on day 0 (D0), D2 and D4 and excised for histological examination. In Study 2, the progress of epithelialization and skin barrier function were monitored to D14. RESULTS: ET increased from D0 to D2 by 46 µm (P<.001) and from D2 to D4 by 19 µm (P=.004). Compared with histology, OCT overestimated the presence of the epithelium (P<.0001) and ET on D4. Reliable measurements were obtained when the ET of the lesions reached the ET of the normal epidermis from D5-D7 and onwards. The ET development was reflected in decreased transepidermal water loss. CONCLUSION: We found that the OCT technique was poorly discriminative with respect to the neoepithelium and the moist lesion surface material in the early postinjury period. In the later stages, OCT seemed valuable for estimating the advancement of epithelialization.

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.

Comparative study of transepidermal water loss in patients with and without hyperhidrosis by closed-chamber measurer in an air-conditioned environment / Estudo comparativo da perda transepidérmica de água em pacientes com e sem hiperidrose por mensurador de câmara fechada em ambiente climatizado

ABSTRACT Objective To evaluate the difference in transepidermal water loss in patients diagnosed with hyperhidrosis and healthy subjects, in an air-conditioned environment. Methods Twenty patients diagnosed with hyperhidrosis and 20 healthy subjects were subjected to quantitative assessment using a closed-chamber device, in six previously established sites. Results The measurements showed different transepidermal water loss values for healthy subjects and patients with hyperhidrosis, especially in the hands and feet. In the Control Group, the median for the hands was 46.4g/m2/hour (p25: 36.0; p75: 57.6), while in the Hyperhidrosis Group, the median was 123.5g/m2/hour (p25: 54.3; p75: 161.2) - p<0.001. For the feet, the Control Group had a median of 41.5g/m2/hour (p25: 31.3; p75: 63.5) and the Hyperhidrosis Group, 61.2g/m2/hour (p25: 32.3; p75: 117) - p<0.02. Measurements of the axillas also showed differences. In the Control Group, the median was 14.8g/m2/hour (p25: 11.8; p75: 19.0) and, in the Hyperhidrosis Group, 83.5g/m2/hour (p25: 29.5; p75: 161.7) - p<0.001. Conclusion Measuring transepidermal water loss is sufficient for diagnosis and follow-up of patients with hyperhidrosis.

RESUMO Objetivo Avaliar a diferença entre a perda transepidérmica de água aferida entre pacientes com e sem diagnóstico de hiperidrose, em ambiente climatizado. Métodos Foram selecionados 20 pacientes com diagnóstico de hiperidrose e 20 hígidos, submetidos à aferição de maneira quantitativa, com mensurador de câmara fechada, em seis locais previamente estabelecidos. Resultados As medidas realizadas mostraram valores diferentes de perda transepidérmica de água em pessoas hígidas e naquelas com hiperidrose, principalmente em mãos e pés. No Grupo Controle, a mediana das aferições em mãos foi 46,4g/m2/hora (p25: 36,0; p75: 57,6), enquanto, no Grupo Hiperidrose, obtivemos a mediana de 123,5g/m2/hora (p25: 54,3; p75: 161,2) - p<0,001. Já nos pés, a mediana no Grupo Controle foi 41,5g/m2/hora (p25: 31,3; p75: 63,5) e, no Grupo Hiperidrose, foi 61,2g/m2/hora (p25: 32,3; p75: 117) - p<0,02. As medidas das regiões axilares também mostraram diferença. No Grupo Controle, obtivemos mediana 14,8g/m2/hora (p25: 11,8; p75: 19,0) e, no Hiperidrose, 83,5g/m2/hora (p25: 29,5; p75: 161,7) - p<0,001. Conclusão A mensuração da perda transepidérmica de água é suficiente para diagnóstico e acompanhamento de pacientes com hiperidrose.

Atopic dermatitis progression: evaluating intervention strategies.

Several risk factors have been identified that appear to be consistently and strongly associated with the development of atopic dermatitis (AD): a family history of atopy, an inherited genetic predisposition, and active and passive exposure to tobacco smoke. Recent studies also have demonstrated that a simple intervention from birth-the daily application of an emollient moisturizer-seems to protect susceptible infants from the development of AD.

Repeat application of microneedles does not alter skin appearance or barrier function and causes no measurable disturbance of serum biomarkers of infection, inflammation or immunity in mice in vivo.

We address, for the first time, the impact of skin insertion on multiple occasions of polymeric microneedle arrays in an animal model in vivo. Dissolving microneedle arrays prepared from aqueous blends of 20% w/w Gantrez® S-97 BF and 40% w/w poly(vinyl pyrrolidone) 58kDa and hydrogel-forming microneedle arrays prepared from aqueous blends of and poly(ethyleneglycol) 10kDa were repeatedly applied to the skin of hairless mice in vivo. Skin appearance and skin barrier function, as illustrated by measurement of transepidermal water loss, were not measurably altered during the entire study period. Biomarkers of infection, immunity and inflammation/irritation were also statistically unchanged, regardless of the microneedle formulation, needle density or number of applications. Mice remained healthy throughout and continued to gain weight during the study. For example, transepidermal water loss values were typically in the range 10-15gm-2h-1 immediately prior to microneedle insertion and 15-25gm-2h-1 immediately following microneedle removal, regardless of when they were measured during the study periods. Serum biomarker levels, measured immediately post-mortem were always in the range 10-20µgml-1 for C-reactive protein, 0.5-1.5mgml-1 for Immunoglobulin G and 1000-2500pgml-1 for interleukin 1-ß and were never statistically different from untreated controls. No measurable levels of tumour necrosis factor-α were found in any animals. These findings are encouraging for the formulations investigated, suggesting that their repeated use by patients will not cause undesirable side-effects. By beginning to address potential regulatory questions at an early stage, the microneedles field will be ideally-placed to take advantage of the potential market. This work illustrates a potential pre-clinical strategy for development of regulatory dossiers on microneedle technologies.

Antioxidant-based topical formulations influence on the inflammatory response of Japanese skin: A clinical study using non-invasive techniques.

Cutaneous irritants exposure induces an excess of ROS in the skin and can ensue an inflammatory response. Topical antioxidant-based formulations can help to counteract ROS generation. This study evaluated the influence of antioxidant-based topical formulations on the inflammatory response of skin, using a combination of in vivo real-time non-invasive techniques. Nine test areas were defined on each volar forearm of the 25 Japanese volunteers. Measurements were performed before and after treatment with 15µL of a 5% sodium dodecyl sulfate solution and 15µL of the same based formulation or the vehicle with 1% of the antioxidants. Volunteers without antioxidant treatment showed more pronounced erythematous areas. Transepidermal water loss of areas treated with green tea polyphenol (GTP)-based formulation showed fully recovered skin. Skin barrier damage caused by repeated applications of SDS showed characteristic alterations, detectable by in vivo confocal microscopy such as desquamation, spongiosis and inflammatory infiltrates. The majority of confocal microscopy inflammation signs were found in skin without treatment followed by the vehicle. Ascorbyl tetraisopalmitate, Coenzyme Q10, GTP- and Resveratrol-based formulations reduced the anti-inflammatory cytokines release and attenuated inflammatory signs. The combination of techniques provides results that highlight the importance of antioxidant-based formulations for rapid skin recovery.

Evaporative Water Loss in Superficial to Full Thickness Burns.

INTRODUCTION: Increased evaporative water loss (EWL) in burn patients leads to dehydration and hypothermia. Early clinical studies performed with outdated hygrometers suggested a 17 to 75 times increased EWL in burns with contradicting results for the different burn depths.Our study proposals were: (1) obtain reliable data of the EWL of all burn depths, (2) compare these results with findings from earlier studies, (3) evaluate the usefulness of the EWL in differentiating between superficial and deep partial thickness burns, (4) determine the effect of Biobrane on the EWL of superficial partial thickness burns in vivo, and (5) evaluate the effect of the sterile incision foil Opraflex on the EWL in split skin graft donor sites. METHODS: We measured the EWL of all burn depths in 28 patients under stable and recorded conditions regarding room temperature and humidity with a modern digital evaporimeter (Tewameter TM 300). For the first time in vivo, we also determined the effect of Biobrane on the EWL of burns and evaluated the EWL in split skin graft donor sites covered with Opraflex. RESULTS: The EWL in all burn depths was significantly increased (P < 0.001) compared with unburned skin. There was no significant difference (P > 0.05) in the EWL of superficial compared with deep partial thickness burns, whereas full thickness burns had a significantly lower EWL (P < 0.05) compared with superficial and deep partial thickness burns. Biobrane significantly reduced the EWL (P < 0.05) of superficial partial thickness burns. The EWL of Opraflex covered skin graft donor sites was significantly reduced compared with uncovered donor sites (P < 0.05). CONCLUSIONS: Our data suggest that the actual EWL in burns is approximately 3 times higher in full thickness burns and approximately 4 times higher in superficial and deep partial thickness burns compared with normal skin and therefore much lower than suggested previously.Because there was no significant difference in the EWL of superficial compared with deep partial thickness burns, the EWL cannot be used to differentiate between these burn depths.Biosynthetic wound dressings can significantly reduce the EWL of superficial partial thickness burns and sterile incision foil protects split skin graft donor sites from an increased EWL.

Skin barrier in rosacea.

Recent studies about the cutaneous barrier demonstrated consistent evidence that the stratum corneum is a metabolically active structure and also has adaptive functions, may play a regulatory role in the inflammatory response with activation of keratinocytes, angiogenesis and fibroplasia, whose intensity depends primarily on the intensity the stimulus. There are few studies investigating the abnormalities of the skin barrier in rosacea, but the existing data already show that there are changes resulting from inflammation, which can generate a vicious circle caused a prolongation of flare-ups and worsening of symptoms. This article aims to gather the most relevant literature data about the characteristics and effects of the state of the skin barrier in rosacea.

Skin barrier in rosacea

Abstract Recent studies about the cutaneous barrier demonstrated consistent evidence that the stratum corneum is a metabolically active structure and also has adaptive functions, may play a regulatory role in the inflammatory response with activation of keratinocytes, angiogenesis and fibroplasia, whose intensity depends primarily on the intensity the stimulus. There are few studies investigating the abnormalities of the skin barrier in rosacea, but the existing data already show that there are changes resulting from inflammation, which can generate a vicious circle caused a prolongation of flare-ups and worsening of symptoms. This article aims to gather the most relevant literature data about the characteristics and effects of the state of the skin barrier in rosacea.

Rutin increases critical wavelength of systems containing a single UV filter and with good skin compatibility.

BACKGROUND/PURPOSE: Ultraviolet (UV) radiation is responsible for sunburns, skin cancer, photoaging, and the production of reactive oxygen species (ROS). The awareness on preventing these deleterious effects made the use of anti-UVB formulations an important part of population habits; however, despite the availability of several antioxidants capable of ROS scavenging, the pharmaceutical market lacks products associating UV filters with natural compounds of proven efficacy. Here, we investigated the effect of rutin, a flavonoid with antioxidant activity, associated with UVB filters in dermocosmetic preparations. METHODS: Formulations were assessed through its antioxidant activity, in vitro photoprotective effectiveness, photostability, and in vivo skin tolerance (hydration, transepidermal water loss, and erythema). RESULTS: Samples containing rutin were compatible with the human skin and presented a pronounced antioxidant potential, with scavenging activity values 75% higher than the ones containing only UVB filters. Although rutin could not prevent the sunscreens photodegradation post-irradiation, the bioactive compound significantly increased the formulations critical wavelengths, showing a photoprotective gain, especially in the UVA range. CONCLUSION: In conclusion, the absorption in the UVA range, coupled with ROS scavenging potential, proved the positive effect of rutin applied to anti-UVB formulations, making this bioactive compound a promising candidate for photoprotection improvement.

Gas valves, forests and global change: a commentary on Jarvis (1976) 'The interpretation of the variations in leaf water potential and stomatal conductance found in canopies in the field'.

Microscopic turgor-operated gas valves on leaf surfaces-stomata-facilitate gas exchange between the plant and the atmosphere, and respond to multiple environmental and endogenous cues. Collectively, stomatal activities affect everything from the productivity of forests, grasslands and crops to biophysical feedbacks between land surface vegetation and climate. In 1976, plant physiologist Paul Jarvis reported an empirical model describing stomatal responses to key environmental and plant conditions that predicted the flux of water vapour from leaves into the surrounding atmosphere. Subsequent theoretical advances, building on this earlier approach, established the current paradigm for capturing the physiological behaviour of stomata that became incorporated into sophisticated models of land carbon cycling. However, these models struggle to accurately predict observed trends in the physiological responses of Northern Hemisphere forests to recent atmospheric CO2 increases, highlighting the need for improved representation of the role of stomata in regulating forest-climate interactions. Bridging this gap between observations and theory as atmospheric CO2 rises and climate change accelerates creates challenging opportunities for the next generation of physiologists to advance planetary ecology and climate science. This commentary was written to celebrate the 350th anniversary of the journal Philosophical Transactions of the Royal Society.

Skin dryness in apparently healthy human skin is associated with decreased expression of bleomycin hydrolase in the stratum corneum.

BACKGROUND: Maintenance of water balance in the stratum corneum (SC) is determined by the content of intercellular lipids and natural moisturizing factors (NMFs) in corneocytes. AIM: To investigate the association between the NMFs and (pro)filaggrin and the proteases responsible for the processing of (pro)filaggrin to NMFs in the SC of hydrated and dry skin areas of healthy human subjects. METHODS: The SC hydration state and the transepidermal water loss (TEWL) were measured using a Corneometer and a Tewameter, respectively. Proteases, (pro)filaggrin and NMFs were extracted from SC samples obtained by tape-stripping of the tested skin. Expression levels of (pro)filaggrin were determined by dot blotting and western blotting, and total NMFs by ultra-high performance liquid chromatography. Expression of the proteases caspase-14, calpain-1 and bleomycin hydrolase was measured by western blotting. RESULTS: The levels of (pro)filaggrin were not significantly different between hydrated and dry skin, whereas the level of total NMFs was significantly reduced in dry skin. A negative correlation between (pro)filaggrin and NMFs was found in dry skin (Pearson correlation coefficient r = - 0.57, *P < 0.05). Bleomycin hydrolase expression was significantly decreased in the SC of dry skin. CONCLUSIONS: These results suggest that the low hydration state of dry skin may be due to the reduction in (pro)filaggrin degradation caused by decreased bleomycin hydrolase expression.

Oxygen-induced plasticity in tracheal morphology and discontinuous gas exchange cycles in cockroaches Nauphoeta cinerea.

The function and mechanism underlying discontinuous gas exchange in terrestrial arthropods continues to be debated. Three adaptive hypotheses have been proposed to explain the evolutionary origin or maintenance of discontinuous gas exchange cycles (DGCs), which may have evolved to reduce respiratory water loss, facilitate gas exchange in high CO2 and low O2 micro-environments, or to ameliorate potential damage as a result of oversupply of O2. None of these hypotheses have unequivocal support, and several non-adaptive hypotheses have also been proposed. In the present study, we reared cockroaches Nauphoeta cinerea in selected levels of O2 throughout development, and examined how this affected growth rate, tracheal morphology and patterns of gas exchange. O2 level in the rearing environment caused significant changes in tracheal morphology and the exhibition of DGCs, but the direction of these effects was inconsistent with all three adaptive hypotheses: water loss was not associated with DGC length, cockroaches grew fastest in hyperoxia, and DGCs exhibited by cockroaches reared in normoxia were shorter than those exhibited by cockroaches reared in hypoxia or hyperoxia.