Barrier creams - skin protectants: can you protect skin?

Barrier creams (BC) are used in hand care to protect the user against damage from surfactants and other irritants; their clinical value remains debatable; some reports indicate that inappropriate BC application might induce a deleterious rather than a beneficial effect. Since many cosmetic formulations contain 'skin protectants', we review concept, application, and efficacy from the pertinent scientific literature.

Efficacy of corticosteroids in acute experimental irritant contact dermatitis?

BACKGROUND/AIMS

Topical corticoids are used to treat irritant contact dermatitis (ICD) in humans. However, their clinical efficacy remains sub judice. This study was designed to assess the efficacy of low- and medium-potency corticosteroids on irritant dermatitis.

METHODS

We induced an acute ICD via open application of sodium lauryl sulphate (SLS) on the hands of subjects. The dorsal side of hands was irritated with 10% SLS five times in one day. Once on day 1 and twice daily on days 2-5, 1% hydrocortisone, 0.1% betamethasone-17-valerate and vehicle cream (petrolatum) were applied subsequently. Visual grading, bioengineering techniques and squamometry were used to quantify skin response.

RESULTS

Corticosteroids were found ineffective in treating the surfactant-induced irritant dermatitis when compared with the vehicle and with the untreated control.

CONCLUSION

The counterintuitive result (in a relatively realistic and robust model) should be interpreted with caution until verified with other irritants of varying physicochemical properties.

Skin occlusion and irritant and allergic contact dermatitis: an overview

Occlusion, widely used to enhance percutaneous absorption of drugs, also increases penetration of other chemicals and antigens, and hence may exacerbate irritant and allergic contact dermatitis. This overview summarizes the adverse effects of occlusion.

Effects of skin occlusion on percutaneous absorption: an overview

Skin occlusion produces profound changes, including hydration status, barrier permeability, epidermal lipids, DNA synthesis, microbial flora, and numerous molecular and cellular processes. It often, but not always, increases percutaneous absorption of applied chemicals. This overview focuses on the effect of skin occlusion on percutaneous absorption.

Novel mutations in spastin gene and absence of correlation with age at onset of symptoms

Autosomal dominant hereditary spastic paraplegia is genetically heterogeneous, with at least five loci identified by linkage analysis. Recently, mutations in spastin were identified in SPG4, the most common locus for dominant hereditary spastic paraplegia that was previously mapped to chromosome 2p22. We identified five novel mutations in the spastin gene in five families with SPG4 mutations from North America and Tunisia and showed the absence of correlation between the predicted mutant spastin protein and age at onset of symptoms.

Color Doppler flow imaging of the facial artery and vein

The purpose of this study was to provide some guidelines with respect to the location of the facial vessels, display the potential inverted blood flow of the facial artery, and reemphasize the value of color Doppler ultrasound studies in flap planning. An anatomic study of the facial artery and vein was done using color Doppler ultrasonography in 12 adults. The artery and the vein were located together at the lower border of the mandible. Around the oral commissure and under the nasal ala, they were located apart from each other with variable distances. This divergence of the facial vein from the artery is important information in the planning of axial pattern flaps. Furthermore, the reverse flow was observed in 12 patients after the blood flow of the facial artery was stopped by applying pressure manually at the lower border of the mandible. Observation of the reversed flow confirms the possibility of safe elevation of a retrograde flow-arterialized flap based on the distal portion of the facial artery.

Antipruritic and thermal sensation effects of hydrocortisone creams in human skin

Few studies evaluate the effect of topical corticosteroids on thermal sensation and in alleviation of itch produced by intradermal injection of histamine. We evaluated the antipruritic effect of hydrocortisone (1% and 2.5%) on histamine-induced itch and sensory effects by measuring itch magnitude, itch duration and thermal thresholds using a computerized thermal sensory analyzer (TSA). This was a double-blind, random, comparative, controlled, single-dose and single-center study. Itch was experimentally induced in both forearms by intracutaneous injection of histamine in 18 subjects. Hydrocortisone 1%, 2.5% and placebo were applied to test sites on both forearms. The thermal threshold for warmth sensation, cold sensation, cold and heat pain was measured with the TSA. Itch magnitude was measured each minute after histamine injection for 10 min with a visual analogue scale (VAS). Itch duration was also recorded. In comparison to placebo, 2.5% hydrocortisone significantly (p = 0.03) reduced itch duration from 12.6 +/- 11.0 min (mean +/- SD) to 8.6 +/- 8.2 min (the reducing rate was 32%) as well as itch magnitude (at minutes 3, 6, 7 and overall). Placebo, 1% and 2.5% hydrocortisone significantly altered (p <0.05) the cold sensation threshold. No treatment altered cold or heat pain thresholds. These data suggest that topical application of 2.5% hydrocortisone may be significantly beneficial for the treatment of histamine-induced itch. The correlation between thermal measurements and antipruritic effects warrants further study.

Strontium nitrate decreased histamine-induced itch magnitude and duration in man

BACKGROUND

Previous studies have demonstrated that strontium salts have a potent and broad ability to suppress sensory irritation.

OBJECTIVE

To ascertain the possible antipruritic effects of topical strontium salts, we conducted a double-blind randomized study to evaluate the effect of 20% strontium nitrate on itch magnitude (intensity) and duration.

METHODS

In 8 human subjects, strontium nitrate was applied to the volar forearm and vehicle control to the contralateral volar forearm for 30 min; both substances were reapplied for an additional 5 min. Itch was then experimentally induced by intradermal injection of histamine. Itch magnitude was rated each minute for the first 20 min using a visual analogue scale (VAS). Itch duration in minutes was also recorded.

RESULTS

Strontium nitrate, in comparison to its vehicle control, significantly shortened itch duration from 28.1+/-5.4 min (mean +/- SEM) to 18.5+/-4.2 min (p<0.01) and reduced itch magnitude at time points 12-20 min and overall (p<0.05).

CONCLUSION

Strontium nitrate may act as a topical antipruritic agent in reducing histamine-mediated itch.

[Hydraulic architecture and drought resistance of woody plants]

This paper introduced with emphasis the physiological meaning of hydraulic architecture and its parameters, e.g., hydraulic conductivity(Kh), specific conductivity(Ks), leaf specific conductivity(LSC), Huber value(Hv) and water storage capacitance(C), the hydraulic architecture patterns of woods and woody plants, and the developmental trend in their research. The relationship between the hydraulic archteciture of woody plants and their drought resistance was tried to be expounded in mechanism.

Strontium nitrate suppresses chemically-induced sensory irritation in humans

Skin care products are complex formulations that may cause sensory irritation symptoms, characterized by stinging, burning, and itching. Substances capable of counteracting sensory irritation are of great practical interest. Strontium salts have been demonstrated to inhibit sensory irritation and inflammation when applied topically. In this double-blind study, we evaluated the efficacy of strontium nitrate in reducing chemically-induced skin sensory irritation in 8 subjects. In a random order, 20% strontium nitrate in 70% glycolic acid (pH=0.6) (mixture) was applied to the volar aspect of the forearm and a positive control (70% glycolic acid, pH=0.6) to the contralateral forearm. The irritation sensation was evaluated each min for the first 20 min after topical application using a scale from 0-4. The duration of the irritation sensation in min was also recorded. Strontium nitrate mixed with glycolic acid, in comparison with glycolic acid alone, markedly (p<0.01) shortened the duration of the irritation sensation from 24.4+/-4.1 (mean+/-SEM) min to 8.9+/-3.7 (mean+/-SEM) min, and significantly (p<0.05) reduced the mean magnitude of the irritation sensation at all time points (overall). The study demonstrated that strontium nitrate potently suppresses the sensation of chemically-induced irritation.

Color pattern recognition in white-light joint transform correlation

We first discuss the restriction on the incoherent source and the color filters in a joint transform correlation (JTC) system for white-light color pattern recognition and then report on a novel, to our knowledge, solution of channeling in a white-light JTC system, using a tricolor grating to encode the color patterns in real time. The theoretical analyses and the experimental results show not only that the restriction on the experimental condition is relieved but also that parallel channeling of the power spectra of the encoded pattern is easily performed. In addition, the zero-order power spectrum also forms a useful channel for the shape-only correlation.

[The relationship between tissue tumor necrosis factor-alpha(TNF-alpha) mRNA expression and gut-derived endotoxemia in rats after thermal injury]

OBJECTIVE

To investigate the dynamic changes in tumor necrosis factor-alpha(TNF-alpha) mRNA expression and the relationship between TNF-alpha mRNA and gut-derived endotoxemia in rats after thermal injury.

METHODS

56 male Wistar rats were subjected to a 35% total body surface area full-thickness thermal injury and randomly divided into 3 groups: normal controls, 35% III* injury group, and polymyxin B treatment group. Plasma endotoxin was measured by limulus amebocyte lysate test, and tissue TNF-alpha mRNA expression was determined by reverse transcription polymerase chain reaction (RT-PCR).

RESULTS

It was found that a significant elevation of endotoxin concentration in both portal and systemic circulation was observed at 2 hours after thermal injury, peaking at 8 hours (P < 0.05-0.01) and lowering at 24 hours. Meanwhile, TNF-alpha mRNA expression significantly increased in liver, lung, intestine, and kidney at 2 hours, peaking at 8 hours, and a high level was maintained till 24 hours. However, treatment with a low-dose polymyxin B could lower both portal and systemic endotoxin levels, and markedly inhibit TNF-alpha mRNA expression in various organs. In addition, a positive correlation between portal endotoxin concentration and pulmonary, intestinal and renal TNF-alpha mRNA expression was noted (r = 0.365-0.484, all P < 0.05).

CONCLUSION

This study suggests that major burns can lead to a marked elevation of tissue TNF-alpha mRNA expression in vital organs, which may be associated with gut-derived endotoxemia caused by acute thermal injury.

Putative skin-protective formulations in preventing and/or inhibiting experimentally-produced irritant and allergic contact dermatitis

The effectiveness of skin protective formulations was evaluated in a previously-described in vivo human model. All formulations failed to inhibit ammonium hydroxide and urea irritation. Only paraffin wax in cetyl alcohol statistically (p<0.01) reduced Rhus allergic contact dermatitis. 3 commercial formulations markedly (p<0.001) suppressed sodium lauryl sulfate irritation. Paraffin wax in cetyl alcohol was quantitatively the most effective formulation. These results suggest that some formulations may provide protective effects against certain, but not all, irritants or allergens.

Asialoglycoprotein receptor and liposome synergistically mediate the gene transfer into primary rat hepatocytes

Gene transfer into primary rat hepatocytes was performed by employing cationic liposome as DNA carrier and the specific ligand of hepatic asialoglycopmtein receptor (ASGPR), asialofetuin, as liver-targeting ligand. The results showed that asialofetuin, when added to the gene transfer complexes, could significantly increase the hepatocyte transfection efficiency, and alleviate the cellular toxicity of Lipofectin. Several synthetic ligands of ASGPR (galactosyl albumin) could also increase the transfection efficiency of hepatocyte like asialofetuin. It was proved that ASGPR and cationic liposome could synergistically mediate the gene transfer into primary rat hepatocytes. This novel gene delivery system provided a safer, more simple and efficient gene transfer method for primary hepatocytes, and showed prospecting application in hepatic gene therapy.

New buccinator myomucosal island flap: anatomic study and clinical application

The authors studied the vascular anatomy of the buccinator muscle by dissecting fresh cadavers. The anatomy of the buccal branches of the facial artery consistently confirmed the existence of a posterior buccal branch, a few inferior buccal branches, and anterior buccal branches to the posterior, inferior, and anterior portions of the buccinator. The buccal artery and posterior buccal branch anastomose to each other and ramify over the muscle. Several veins originate from the lateral aspect of the muscle, converge into the buccal venous plexus, and drain into the facial vein (from two to four tributaries) or into the pterygoid plexus and the internal maxillary vein (from the buccal vein). These vessels and nerves enter the posterior half of the buccinator posterolaterally. The facial artery and vein are located at variable distances from each other around the oral commissure and the nasal base. Two patterns of buccinator musculomucosal island flaps supplied by these buccal arterial branches are proposed in this article. The buccal musculomucosal neurovascular island flap (posteriorly based), supplied by the buccal artery, its posterior buccal branch, and the long buccal nerve, can be passed through a tunnel under the pterygomandibular ligament for closure of mucosal defects in the palate, pharyngeal sites, the alveolus, and the floor of the mouth. The buccal musculomucosal reversed-flow arterial island flap (superiorly based), supplied by the distal portion of the facial artery through the anterior buccal branches, can be used to close mucosal defects in the anterior hard palate, alveolus, maxillary antrum, nasal floor and septum, lip, and orbit. The authors have used the flaps in 12 patients. There has been no flap necrosis, and results have been satisfactory, both aesthetically and functionally.

In vivo nickel allergic contact dermatitis: human model for topical therapeutics

Techniques to determine efficacy of topical agents on allergic contact dermatitis (ACD) may benefit from refinement. The aim of this study was to develop an in vivo human model system for the bioengineering and visual quantification of the effect of topical agents on nickel ACD, and to correlate ACD parameters. 14 nickel patch-test-positive subjects were included in a placebo-controlled, double-blind study after a pre-screening procedure with a standard diagnostic patch test with nickel sulfate in 54 healthy human volunteers. 5% nickel sulfate in petrolatum in a Finn Chamber was applied on forearm skin for 48 h to create a standardized dermatitis. Thereafter, the dermatitis was treated with a model topical agent and a placebo control while recording endpoint parameters daily for 10 days. Resolution was quantified with 4 parameters: visual scoring (VS), transepidermal water loss (TEWL) (Tewameter), skin blood flow volume (BFV) (laser Doppler flowmeter), and skin color (a* value) (Colorimeter). The model agent reduced cutaneous allergic reactions, especially on day 8 to 10, in comparison with the placebo control. A highly significant linear relationship exists among all parameters, except between a* and BFV. This model may provide robust biometrics for determining the efficacy of topical therapeutics on experimentally induced ACD.

[Effects of short veno-venous hemofiltration on severe acute pancreatitis]

OBJECTIVE

To estimate the effects of therapy of short veno-venous hemofiltration (SVVH, 4hr) on severe acute pancreatitis (SAP).

METHODS

Twenty patients were divided randomly into hemofiltration group (HF, 10 pts) and non-hemofiltration group (NHF, 10 pts). The local, systemic manifestations were compared between two groups; and the concentration of serum pro-inflammatory cytokines (TNFalpha, IL-1beta, IL-6, IL-8, sIL-2R) and anti-inflammatory cytokines (IL-2, IL-10) were determined at different observation points.

RESULTS

In the HF and NHF group, the duration for disappearance of abdominal pain and tenderness, and amelioration for abdominal distension was (8.5 +/- 6.3) d vs. (90.0 +/- 49.0) d and (16.9 +/- 5.2) d vs. (63.4 +/- 36.0) d. CT scores at the 14th day and APACHE II scores at the 10th day was (5.6 +/- 1.3) vs. (7.7 +/- 0.8) and (4.5 +/- 1.5) vs. (7.4 +/- 2.1). The average hospital stay and cost of therapy were (33.0 +/- 20.7) d vs. (56.4 +/- 16.0) d and (53,200 +/- 16,000) vs. (89,100 +/- 25,000) RMB (P < 0.05). The concentration of 5 serum pro-inflammatory cytokines at each observation points after hemofiltration was decreased significantly (P < 0.05) in the HF group. But the concentration of the two serum anti-inflammatory cytokines was increased significantly (P < 0.05) as compared with that of the NHF group.

CONCLUSIONS

Through SVVH, the imbalance of pro-inflammatory and anti-inflammatory cytokines has been corrected at early stage; thus, the severity of the disease is ameliorated significantly and the efficacy of therapy is increased.

[Effect of TNF-alpha monoclonal antibody on tissue lipopolysaccharide-binding protein mRNA expression in rats after thermal injury]

OBJECTIVE

To explore the effects of tumor necrosis factor-alpha (TNF-alpha) monoclonal antibody (MAb) on tissue TNF-alpha and lipopolysaccharide-binding protein (LBP) mRNA expression, and multiple organ dysfunction in rats after thermal injury.

METHOD

24 male Wistar rats were subjected to a 35% total body surface area full-thickness thermal injury.

RESULT

The tissue TNF-alpha and LBP mRNA expressions of liver, lung, intestine, and kidney were markedly increased (P < 0.05 approximately equal 0.01) after thermal injury. Treatment with TNF-alpha MAb could significantly lower TNF-alpha mRNA expression of lung, intestine and kidney, but had no effect on liver TNF-alpha mRNA expression (P > 0.05). Similarly, the tissue LBP mRNA expression also decreased significantly (36.0% - 72.9%), and returned to normal in lung, intestine and kidney. In addition, biochemical parameters including GPT, TBiL, BUN, CK-MB, and LDH were markedly elevated after thermal injury, and decreased significantly after treatment with TNF-alpha MAb.

CONCLUSION

The increase of tissue TNF-alpha gene expression caused by thermal injury might be associated with a marked elevation of tissue LBP mRNA expression, which could contribute to the development of multiple organ dysfunction. The early use of TNF-alpha MAb seems to be effective in inhibiting significant LBP mRNA expression in various tissues and ameliorating multiple organ damage after major thermal injury.

Effectiveness of ammonium solution in relieving type I mosquito bite symptoms: a double-blind, placebo-controlled study

A randomized, double-blind, placebo-controlled study was conducted to compare the efficacy of ammonium solution with placebo in relieving type I symptoms caused by Aedes aegypti mosquitoes on 25 healthy subjects. Each subject was bitten once under laboratory conditions by Aedes aegypti mosquitoes on the volar aspect of each forearm, and then received the treatment with ammonium solution and placebo, respectively. Compared with placebo, the ammonium solution significantly (p < 0.0001) decreased itching/burning/pain immediate type symptoms from 5 to 90 min. Complete and partial relief of the symptoms was noted in 64% in the ammonium solution group compared to none in the placebo group.

Human in vivo and in vitro hydroquinone topical bioavailability, metabolism, and disposition

Hydroquinone is a ubiquitous chemical readily available as monographed in cosmetic and nonprescription forms for skin lightening, and is an important industrial chemical. The in vivo bioavailability for 24-h application in humans was 45.3+/-11.2% of dose from a 2% cream formulation containing [14C]hydroquinone, with the majority of radioactivity excreted in the first 24 h. Timed skin wash and skin tape-stripping sequences showed a rapid and continuous movement of hydroquinone into the stratum corneum of human volunteers. Plasma levels taken both ipsilateral and contralateral to the topical dosing site contained radioactivity at the first 0.5-h sampling time. Peak plasma radioactivity was at 4 h in the 8-h blood sampling period. In vitro percutaneous absorption with fresh viable human skin gave a bioavailability of 43.3% of dose, and flux was calculated at 2.85 microg/cm2/h. In vitro, some of the skin samples were pretreated with the metabolic inhibitor sodium azide, which had no effect on percutaneous absorption. Receptor fluid accumulations and 24-h skin samples were extracted and the extracts subjected to thin-layer chromatography (TLC). Control [14C]hydroquinone extraction and TLC had one radioactivity peak, hydroquinone. Receptor fluid and skin extraction had a second peak with the same Rf as benzoquinone, which was decreased with azide treatment. No other peaks were found. Ethyl acetate extraction of urine from the in vivo study showed all radioactivity to be only water-soluble, free hydroquinone released following glucuronidase treatment. Risk assessment should not only involve the bioavailability of intact topical hydroquinone, but also consider phase I and phase II metabolism in both humans and any animal for which toxicity potential was assessed.

[Anti-tumor effect of cytotoxic T lymphocytes induced by soluble antigen of ovarian carcinoma and anti-CD3 monoclonal antibody on ovarian carcinoma]

OBJECTIVE

To evaluate the therapeutic effect of the new method--adoptive cell immunotherapy on ovarian carcinoma.

METHODS

Tumor soluble antigen (TSA) was extracted from cells of ovarian carcinoma (COC1 and COC2n). To generate cytotoxic T lymphocytes (CTL), peripheral blood mononuclear cells (PBMC) collected from healthy persons were induced by TSA and anti-CD3 monoclonal antibody (CD3-McAb). The antitumor effect of CTL on COC1 cells in vitro was compared with LAK and CD3-AK, whereas the growth inhibitory effect of CTL on COC2n transplantation tumors in nude mice was compared with CD3-AK.

RESULTS

The cytotoxicity of CTL, CD3-AK and LAK was 79.4%, 52.1% and 51.7% respectively (P < 0.01). Mean volume of tumor in nude mice on the 9th day after ovarian carcinoma cells transplanted was 44.4 +/- 24.2 mm3 in CTL group, 118.8 +/- 40.0 mm3 in CD3-AK group and 443.0 +/- 158.7 mm3 in control (no treatment) (P < 0.01), whereas mean duration of survival was 28.5 days, 25.5 days and 17 days respectively (P < 0.01).

CONCLUSION

The results indicated that CTL exhibited higher cytotoxic effect in vitro and greater inhibitory effect on tumor growth resulting in longer survival in vivo. It suggested that the adoptive cell immunotherapy might provide a new idea for treatment of ovarian carcinoma.

Stripped skin model to predict irritation potential of topical agents in vivo in humans

BACKGROUND AND OBJECTIVE

The prediction of the irritation effects of products of low irritation potential remains problematic. An in vivo human model was utilized to define the irritation potential of a topical agent after partial removal of the stratum corneum by cellophane tape stripping.

METHODS

The tape was applied to and removed approximately 50 times (mean, 50.0 +/- 16.7) from each test site on the volar aspect of the forearm. One site served as the stripping control, receiving tape stripping only. The other test sites received the topical agent and placebo control. Transepidermal water loss (TEWL) was measured before and daily for 5 days. The TEWL values at baseline after stripping represented the point of maximal stripping barrier disruption. The barrier disruption and irritation potential were assessed with TEWL measurements.

RESULTS

The results showed that the model topical agent had no adverse effect on barrier repair, i.e. did not interfere with TEWL normalization.

CONCLUSIONS

This model provides a method for the prediction, with exaggerated sensitivity, of chemical irritation and proclivity to enhance or retard water barrier repair. We believe that the model may predict the response of low irritation materials and may be more sensitive than patch testing on normal skin, particularly for products to be used on certain areas, e.g. the face, anus, etc., or even mucous membranes. The model must receive extensive use with chemicals of varying properties in order to define its chemical relevance.

Moisturizers in preventing irritant contact dermatitis: an overview

Moisturizers, widely used in dermatologic and cosmetic "dry" skin treatments, can improve the skin condition by increasing stratum corneum water content and by other mechanisms. We review the controlled study data that relate to their use in the prevention of irritant contact dermatitis.

Evaluating skin-protective materials against contact irritants and allergens. An in vivo screening human model

2 acute irritants and 1 allergen were selected: sodium lauryl sulfate (SLS) representative of irritant household and occupational contact dermatitis, the combination of ammonium hydroxide (NH4OH) and urea to simulate diaper dermatitis, and Rhus to evaluate the effect of model protective materials. The putative protective materials and vehicle were applied to both ventral forearms of 10 subjects in each group, according to a randomized code. Test materials were spread over a marked 2.0 cm2 area, massaged in, allowed to dry for 30 min, and reapplied with another 30 min drying period. The model irritants and allergen were then applied (0.025 ml) to an Al-test occlusive patch, which in turn was placed for 24 h over each of the 8 designated sites. Inflammation was scored according to a clinical scale 72 h post-application. Paraffin wax plus Acetulan in cetyl alcohol, and beeswax plus Acetulan in cetyl alcohol, markedly (p < 0.001) suppressed SLS irritation. Paraffin wax plus beeswax in cetyl alcohol, and Acetulan in cetyl alcohol reduced NH4OH and urea irritation (p < 0.05), paraffin wax in cetyl alcohol significantly (p < 0.01) decreasing Rhus allergic contact dermatitis. This model, provides an easy approach to screening protectants. Its clinical significance requires comparison with an open rather than an occluded challenge.

Human barrier recovery after acute acetone perturbation: an irritant dermatitis model

The efficacy of a topical agent in barrier recovery was evaluated after acetone-induced acute water loss barrier disruption in vivo in humans. The upper back of several volunteers was rubbed with acetone-soaked cotton balls until elevated rates of transepidermal water loss (TEWL) occurred (> 20 g/m2h, or greater). The topical agent was then applied to the acetone-treated skin sites once daily for 5 days. Resolution evaluation used TEWL measurements and the data were expressed as the percentage recovery in water barrier function. In comparison with placebo control the topical agent significantly enhanced barrier recovery, especially within the first 72 h (P < 0.05). This model offers a simple method of examining chemicals accelerating (or inhibiting) repair of this form of acute skin damage in man.

Effect of barrier creams: human skin in vivo

An in vivo method was developed to measure the effectiveness of skin protective creams against 2 dye indicator solutions: methylene blue in water and oil red O in ethanol, representative of model hydrophilic and lipophilic compounds. 3 representative barrier creams commercialized as effective against lipophilic, hydrophilic, or lipophilic and hydrophilic substances were assayed by measurements of the dye in cyanoacrylate strips of protected skin samples after various application times. The flexural surfaces of the forearms of 6 normal volunteers (3 female and 3 male, mean age 26.8 +/- 4.1 years) were treated. The method was as follows: solutions of 5% methylene blue in water and 5% oil red O in ethanol were prepared, and applied to untreated skin and protective-cream-pretreated skin with the aid of aluminum occlusive chambers, for 0 h and 4 h, respectively. At the end of the application time, the creams were removed. Consecutive skin surface biopsies (SSB) from 1 to 4 strips were taken. The amount of stain in each strip was determined by colorimetry, and the cumulative amount of stain from 1 to 4 strips in each measurement was calculated. The cumulative amount represents the amount of permeation of each solution at each time point, and the efficacy of skin barrier cream. The results showed one formulation at both 0 h and 4 h reduced the amount of permeation of methylene blue (p < 0.01) and oil red O (p < 0.01) compared with the control group. Another formulation was protective against the permeation of oil red O (p < 0.01), but not against methylene blue at 0 h and 4 h; it was not significantly different at 0 h versus 4 h. The 3rd formulation produced increased cumulative amounts to oil red O at both 0 h and 4 h (p < 0.05); it also increased permeation amounts to methylene blue (p < 0.05) after 4 h. This model appears a facile, rapid and objective early screen to evaluate the efficacy of skin barrier creams in vivo, as well as their individual ingredients.

Clinical and laboratory investigations of the relationship of accommodation and convergence function with refractive error. A literature review

Studies of the relationship of clinical and laboratory measures of accommodation and convergence function with refractive error are reviewed. There are inconsistencies in results from study to study presumably due, in part, to methodological differences. However, some basic trends can be outlined. In studies in young adults, accommodation in darkness (dark focus), optical reflex accommodation, and proximally induced accommodation are less in myopes than in emmetropes and hyperopes. It also appears that nearpoint esophoria is associated with higher rates of myopia progression in children. Implications for myopia etiology are discussed.

The effect of caffeine on the accommodative response/accommodative stimulus function and on the response AC/A ratio

Using a phoro-accommodometer, accommodation and convergence responses were measured for 17 experimental subjects before and after they ingested 200 mg caffeine. For 16 control subjects accommodation and convergence responses were determined at two test sessions separated by 45 min. For the experimental group, the accommodative response/accommodative stimulus (Ar/As) slope increased 0.05 D/D after ingestion of caffeine, and the response AC/A ratio decreased 3.05 delta/D. The y-intercept of the convergence response/accommodative response increased by 3.7 delta in the experimental group. These changes were statistically significant. For the control group, the differences in Ar/As slope, response AC/A ratio, and convergence response/accommodative response y-intercept between first and second test sessions were not statistically significant.