Biomedical subjects

Hongbo Zhai

Publications and source records attributed to Hongbo Zhai.

12 recordsLinked to original sources

PubMed2005

Allergic contact dermatitis from iodine preparations: a conundrum.

Iodine preparations are widely used antiseptics, yet limited information exists on their irritant potential and threshold for diagnostic patch testing. We examine this issue by using iodine in different preparations and concentrations. A total of 24 fair-skinned, healthy volunteers without a history of iodine allergy, ranging in age from 18 to 65 years (mean age 49.5 + 10.7 SD), were recruited. Concentrations of 0.5%, 1%, 5% and 10% iodine in petrolatum (pet.), 0.5%, 0.75% and 1% iodine in 70% isopropyl alcohol (IPA) and 1%, 5%, 7.5% and 10% of povidone-iodine (PVP-I) were applied for 2 days to the intrascapular area on the back or to the volar forearm between cubital fossa and wrist using Finn Chambers on Scanpor. Test sites were read 2 days (D2) and 4 days (D4) after patch application. Skin reactions were graded according to the following scheme: 0 = no reaction, + = questionable erythema, 1 = definite erythema, 2 = erythema and induration and 3 = vesiculation. Mild-to-moderate reactions (+ to 2) were observed in 75% of the subjects patched with 5% iodine in pet. at 2-4 days after application. Almost all subjects reacted to 10% iodine at D2 and D4, with 65% exhibiting erythema and induration or vesiculation. A large number (33%) of the subjects developed some reactions to the low concentration (0.5%) of iodine in 70% IPA at D2. Vesicles were seen in 54% of the subjects patched with 1% iodine in 70% IPA at D4. Only 1 subject reacted to 7.5% and 10% PVP-I. Iodine can be irritant to normal skin in pet. and in 70% IPA. Pet. possibly enhances skin contact with iodine, thus increasing its irritant capacity. Alcohol removes sebum from the skin surface, and it might increase iodine penetration into the skin, causing a higher degree of irritation. PVP-I is relatively non-irritant, because its iodine is complexed in an iodophor. For diagnostic patch testing, we recommend using iodine at less than 1% in pet. and at less than 0.5% in 70% IPA. For PVP-I, 10% appears non-irritant. With the variation in patch-test irritant response, interpretation of the patch-test response in the light of clinical history is mandatory.

2-Propanol↗

PubMed2005

Long-term repetitive sodium lauryl sulfate-induced irritation of the skin: an in vivo study.

Skin may adapt to topical irritants through accommodation. This study focuses on long-term exposure to irritants and attempts to demonstrate accommodation. Sodium lauryl sulfate (SLS) induced irritant contact dermatitis at 3 concentrations (0.025% to 0.075%). Distilled water, acetone and an empty chamber served as controls. Experimental compounds were applied to forearms of 7 healthy volunteers for 24 hr before replacing by a fresh chamber for 6 non-consecutive weeks over 103 days. Possible accommodation was quantified by visual scoring (erythema and dryness) and by bioengineering parameters: transepidermal water loss (TEWL), capacitance, chromametry and laser Doppler flowmetry (LDF). Significant erythema, dryness, elevated TEWL, skin colour reflectance and LDF values occurred during the exposure periods. Upon repeat exposure, an immediate and augmented response in erythema, TEWL, skin colour reflectance and LDF developed. However, irritant skin changes were not sustained. Irritation parameters return to baseline after cessation of exposure. There was no evidence of sustained irritation or accommodation after the last exposure. Study findings do not document sustained accommodation or adaptive hyposensitivity after long-term repetitive irritant exposure under these test conditions. Alternative models should be developed to prove or disprove the accommodation hypothesis.

Adaptation, Physiological↗

PubMed2005

Comparative evaporimetry in man.

BACKGROUND/AIMS: Transepidermal water loss (TEWL) measurements are frequently used; the most widely utilized instrument has been the open chamber device. Traditional open-chamber systems for measuring TEWL have limitations related to ambient and body-induced airflows near the probe, probe size, measurement site and angles. Recent technology provides a portable and battery-operated closed chamber Evaporimeter. It is presumably less affected by external factors such as room- or body-induced airflows, breathing or heating of the probe by the operators' hand. This study compares this commercial instrument, a closed chamber device, with a traditional open-chamber device. METHODS: Two open chamber devices and one closed chamber device were used in such a way that each instrument could simultaneously measure TEWL in an identical experimental environment with known relative humidity and temperature values. TEWL values of seven locations on healthy volunteers were measured simultaneously with each instrument in the same room according to the guidelines of the standardization group of the European society of contact dermatitis. RESULTS: For TEWL values of all forearm locations, there was no statistically significant difference between the mean values measured by all three instruments. For TEWL values of forehead locations, there was a significant difference between the mean values of open chamber device and closed chamber device. For the forehead, values from closed chamber device were higher than the open one. CONCLUSION: The TEWL values measured by all instruments were constant with small standard deviations. These instruments appear sufficiently robust that a standardization group could document similarities and differences with in vitro models. We suspect that both techniques will continue to be used and that the closed method will find increasing use because of its ease of use.

Adult↗

PubMed2005

Clinical microneedle injection of methyl nicotinate: stratum corneum penetration.

BACKGROUND/PURPOSE: In recent years, microneedles were proposed as a method to painlessly deliver drugs past the stratum corneum. Microneedles have been fabricated in several designs, but limited studies have tested microneedle injections in humans. In this work, we compare microneedle injections with topical application (TA) to investigate if microneedles enhance in vivo drug delivery past the stratum corneum. METHOD: In vitro tests were used to measure microneedle pressures and injection volumes. In vivo microneedle injections were performed on the volar forearm of 11 healthy volunteers. Two sets of microneedles, pointed and symmetric, were used to develop microneedle/syringe apparatuses that were used to inject approximately 1 microL of 0.1 M methyl nicotinate, and were compared against TA. A Laser Doppler Perfusion Monitor was used to record maximum blood flow and the time to maximum blood flow at the treatment sites. RESULTS: Pointed and symmetric microneedle-injected sites showed a significantly faster time to maximum blood flow than TA. The pointed microneedle injections also resulted in a higher maximum blood flux. Volunteers reported feeling pressure but no pain from the microneedles during the injections. CONCLUSION: The microneedles aid in bypassing the stratum corneum and enhance drug delivery through it. The design of the microneedle influences its delivery capabilities, because the pointed microneedles seem to be less susceptible to clogging during the injection.

Administration, Topical↗

PubMed2004

Human scalp irritation compared to that of the arm and back.

Large-scale data comparing reactions to surfactants between scalp and back and arm are lacking. The sensitivity of responses between scalp and back and arm were explored utilizing an open-application model for testing the potential irritancy of sodium lauryl sulphate (SLS). 10 bald male Caucasians (mean age 56 +/- 9 years) were enrolled. We conducted 5 successive washings: for each wash, the technician pipetted 1 ml of 20% SLS solution into a glass cylinder placed on the designated area with hand pressure that prevented the cylinder leaking. The test area was then rubbed with a Teflon Policeman scrubber for 1 min. Post scrubbing, the solution was absorbed dry with a plastic pipette and blotted by gently applying paper tissues. After a 5-min rest, the procedure was repeated for 4 more times for a total of 5 times. Skin-irritancy assessments by visual scoring and instrumental measurements were made at 30 min and 24 h thereafter and squamometry at the end of last washing. Results indicated that most param- eters revealed that the back was most sensitive to the SLS challenge. Thus, these data support the current standard skin-compatibility testing procedure, employing the back for potential irritation testing of hair care products.

Arm↗

PubMed2003

A rapid, accurate, and facile method to quantify the antioxidative capacity of topical formulations.

BACKGROUND/AIMS: Various methodologies have been developed to quantify antioxidant activity. A simple, rapid and accurate method is demanded. This study examined the antioxidative status of a pH balanced vitamin E containing formulation versus its vehicle control utilizing a photochemiluminescence device. METHODS/RESULTS: A pH balanced 5% Vitamin E containing formulation and its vehicle control were tested. The quantity of antioxidant capacity for the pH balanced vitamin E formulation and its vehicle control were 2.28 +/- 0.05 and 0.16 +/- 0.03, respectively. The pH balanced vitamin E formulation showed a significant (P < 0.001) higher antioxidant capacity compared to its vehicle control. CONCLUSIONS: This method not only provides quantitative data, but also is rapid, accurate, and facile in performance. The in vitro data obtained in this study require validation by in vivo studies to properly place them in context to alternate methods.

Administration, Topical↗

PubMed2003

[Hydraulic characters of Acer truncatum seedlings].

The hydraulic parameters of 4 years old Acer truncatum seedlings were measured by improved flushing method under the condition of controlled drought gradients in the greenhouse. It's indicated that the changes of hydraulic parameters with stem segment functional xylem diameter could be modeled by different equations. The hydraulic conductivity was influenced by the area that stem segment located. It was higher in non-constriction area than in constriction area. The existence of constriction area was in favor of the competition between individual seedlings. Hydraulic conductivity, specific conductivity and leaf specific conductivity were proportional with functional xylem diameter and twig water potential. The leaf specific conductivity of thicker branches was far higher than that of distal twigs, which was in favor of seedlings in saving those organs with more photosynthesis devotion during drought stress. The change of Huber value of same diameter branches with twig water potential was very small before defoliation, and hence, the main source of seedling's water stress came from xylem cavitation and embolism.

Acer↗

PubMed2002

Dosage considerations in patch testing with liquid allergens.

This study examines reproducibility of water and ethanol drop volumes from plastic squeeze dropper bottles, examines the difference in drop volumes between commonly used liquid patch test solutions, and evaluates the volumes of water and ethanol needed to saturate Finn and IQ Chamber filter papers. 2 plastic squeeze dropper bottles recommended for use in patch testing have poor reproducibility compared to other bottles tested. 3 aqueous allergens tested (formaldehyde 1%, methylchloroisothiazolinone/methylisothiazolinone 0.01%, and dimethylol dihydroxyethyleneurea 4.5%) have drop volumes equivalent to water. Smaller drop volumes are produced by ethanol, hydrocortisone butyrate 1% in ethanol, cocamidopropyl betaine 1% a.q., and propylene glycol 30% a.q. Filter paper saturation volumes using distilled water are 16-19 micro L in standard Finn Chambers and 29-35 micro L in IQ Chambers. Ethanol saturation volumes are slightly lower. Previously recommended volumes of application for aqueous allergens of 15 micro L for standard Finn Chambers and 25 micro L for IQ Chambers (slightly below the filter paper saturation points) are appropriate. Selection of dropper bottles should consider drop volume reproducibility, differing drop volumes for different allergens, and the patch test chamber system being used.

Allergens↗

PubMed2002

Occlusion vs. skin barrier function.

BACKGROUND/AIMS: Skin occlusion may increase percutaneous absorption of applied chemicals, with some exceptions. It also obstructs the normal ventilation of the skin surface and increases stratum corneum hydration and hence compromises skin barrier function. METHODS/RESULTS: This review focuses the effects of occlusion on skin barrier function, in particularly, as defined with objective skin bioengineering technology. CONCLUSIONS: The effects of occlusion on skin barrier function have been defined with various techniques. Optimal hydrocolloid materials can absorb excess water and reduce the unfavourable effects of occlusion.

Administration, Cutaneous↗

PubMed2002

Hydration vs. skin permeability to nicotinates in man.

BACKGROUND/AIMS: Prolonged skin occlusion increases stratum corneum water content and often increases skin permeability and irritant dermatitis. As skin wetness from wearing diapers is considered an important factor favouring the onset of diaper dermatitis, optimal diapering might decrease skin hyperhydration and dermatitis. Our aim is to define the quantitative relationship between nicotinate ester (a model penetrant) skin permeability and hydration, as measured by water evaporation rate (WER), decay curves (at individual time points) and WER-area under the curve (WER-AUC); and also to determine the level of skin hydration and skin permeability to nicotinates following a diapering simulation. METHODS/RESULTS: Nine healthy Caucasian adult women were enrolled after a prescreening procedure (time to peak redness response to nicotinate); each received three wet occlusive patches for different exposure times (10 min, 30 min, and 3h) and two wet model diapers (3 and 8 h). Prior to patching or diapering of forearms, basal values of WER, skin blood flow volume (BFV), capacitance (Cap) and redness (a*) were measured on premarked sites (a, b, c and d). Immediately, following occlusive patch or diaper removal, 20 microL of each nicotinate (methyl and hexyl nicotinate) was applied to its respective site (a or b). The WER and Cap readings were recorded at designated sites (c and d) with the following intervals after nicotinate applications: 0, 5,10,15 and 20 min. The a* and BFV measurements were made on each nicotinate challenged site (a and b) with the following intervals after nicotinate applications: 5, 10, 15, 20, 30, 40, and 60 min. RESULTS: WER-AUC and thus, skin hyperhydration, increased with occlusive patch and diaper exposure time, but there was no statistical difference between 3 and 8h diaper sites. All patched sites had significantly (P<0.05) increased hydration in comparison to control sites (undiapered or unpatched skin). Cap increased with occlusion time with patches, but not with diapers. The degree and time-course of redness from nicotinates did not vary with extent of skin hydration, but was significantly increased compared to non-hydrated skin. BFV-AUC did not show a significant increase between diapers at 3 and 8h sites; the BFV-AUC values varied on the patched sites, but some were significantly (P<0.05) higher than control site. CONCLUSION: Wet patches and diapers increased skin hyperhydration proportional to exposure time. Permeation of nicotinates was increased for hydrated skin vs. control, even after only 10 min of patch exposure. For these model permeants, we found no evidence of increased permeation rates with increased hyperhydration, once a relatively low threshold of hyperhydration was achieved (e.g. that reached after a 10 min wet patch). The data showed no meaningful differences in permeation following either diapering simulation and also suggested that the WER-AUC method was superior to capacitance for measuring the absolute extent of hyperhydration. We believe this is a suitable model for evaluating the quality of diaper product performance, as well as in pharmacologic assays of occlusive therapy.

Adult↗

PubMed2000

A bioengineering study on the efficacy of a skin protectant lotion in preventing SLS-induced dermatitis.

BACKGROUND/AIMS: This study evaluated the efficacy of a dimethicone skin protectant lotion against sodium lauryl sulfate (SLS)-induced irritant contact dermatitis (ICD) by clinical visual grading and bioengineering techniques in 12 healthy humans. METHODS: The flexor aspects of both forearms of the subjects were used as test sites. Each test was duplicated to diminish the variations of the test sites. In a random order and a double-blind manner, two test sites were pretreated either with the testing protectant lotion or with its vehicle control prior to contact with SLS. Thirty minutes later, 0.2 ml of 0.5% SLS in a polypropylene chamber was applied to each pretreated site. One additional test site served as a positive control (without lotion), receiving the irritant only. After 24 h of exposure to the irritant, the chambers were removed. The efficacy of protective effect was determined by four parameters: visual scoring (VS), transepidermal water loss (TEWL), skin color (a* value), and cutaneous blood flow volume (BFV). All test sites were assessed with the parameters daily for 5 days. RESULTS: The VS data showed a significant decrease on the site pretreated with protectant lotion in comparison with the SLS-only treated site (P<0.01) and with the site pretreated with control vehicle (P<0.05) (overall for 5 days). TEWL value was significantly decreased in comparison with the SLS-only treated site (P=0.02 at day 2; P=0.008 at day 4; P=0.014 at day 5) and with the site pretreated with the control vehicle (P<0.05) (day 2, 4 and 5). However, the BFV and a* values did not show a statistical difference between protectant lotion, vehicle, and SLS-only treated sites. CONCLUSIONS: This study demonstrated that appropriate dimethicone skin protection products may provide certain benefits from surfactant ICD. The skin protectant lotion may be used to prevent ICD in home or work environments, where skin irritants may induce dermatitis or eczema.

Journal Article↗

PubMedDate not supplied

Screening topical antipruritics: a histamine-induced itch human model.

Itch is a subjective symptom; its magnitude (intensity) may be only estimated by the reports of patients or volunteers. We utilized a comparative screening method to identify and quantify the efficacy of topical antipruritics with a histamine-induced itch human model. Ten individuals responsive to histamine-induced itch sensation were enrolled. Both forearms served as test sites. Each test site was treated randomly either by histamine injection only or pretreated with a coded candidate formula for 30 min and then a histamine injection. Itch was experimentally induced in each test site by the intracutaneous injection of 100 microg histamine dihydrochloride dissolved in 1 ml normal saline. Itch magnitude was measured each minute after histamine injection for 20 min with a magnitude visual analogue scale. Itch duration was also recorded. Formulation D significantly (p < 0.05) decreased itch magnitude (within a 20-min test period), from 2.6 +/- 2.1 cm (mean +/- SD) to 2.2 +/- 2.1 cm (mean +/- SD) when compared to its vehicle control; it also significantly (p < 0.05) shortened itch duration (15.0 +/- 7.4 min; mean +/- SD) in comparison with its vehicle control (20.3 +/- 7.0 min; mean +/- SD). Of all the formulations tested, formulation D was the most effective antipruritic in decreasing histamine-induced itch. This method may act as a simple and robust screening procedure when evaluating potential antipruritics and allow a comparison among products. Until validated with disease-induced itch, e.g., atopic dermatitis, the model should be considered screening in nature.

Administration, Cutaneous↗