The evaluation of synchronous and asynchronous online learning: student experience, learning outcomes, and cognitive load

BACKGROUND

The abrupt onset of the COVID-19 pandemic compelled universities to swiftly establish online teaching and learning environments that were not only immediately deployable but also conducive to high-quality education. This study aimed to compare the effectiveness of the online synchronous and asynchronous teaching formats in the dermatology lecture for undergraduate medical students, including academic performance, self-efficacy, and cognitive load.

METHODS

A total of 170 fourth-year undergraduate medical students attending the dermatology lecture were included. The lecture was delivered using both the synchronous method (live online lecture via Webex meeting) and the asynchronous method (lecture videos shared on YouTube). The students had the freedom to choose their preferred method of attending the online lecture. The study assessed three main aspects: (1) learning outcomes measured through pretest, posttest, and retention test scores; (2) cognitive load experienced by students, including mental load and mental effort measured using eight items; and (3) satisfaction levels with each online teaching format.

RESULTS

In this study, 70 students opted for the synchronous online lecture, while 100 students chose the asynchronous online lecture. Both synchronous and asynchronous teaching methods exhibited significant improvements in post and retention test scores compared to the pretest. Satisfaction levels, rated on a scale of 0-5, were generally high for both teaching methods, with no significant differences observed (4.6 for synchronous, 4.53 for asynchronous; p =.350). Regarding cognitive load, the synchronous method showed a significantly lower level than the asynchronous method (p =.0001). Subgroup analysis revealed no difference in mental effort (p =.0662), but the level of mental load was lower in the synchronous method (p =.0005).

CONCLUSIONS

Both synchronous and asynchronous online teaching methods demonstrated improvements in learning outcomes and high levels of student satisfaction. However, the cognitive load experienced by students was lower in the synchronous setting compared to the asynchronous setting. These findings remind health professions educators that they would consider the students' cognitive load when designing online curricula.

Hormone replacement therapy did not increase risk of melanoma in Chinese female with menopausal and postmenopausal disorders: A population-based retrospective cohort study in Taiwan

Hormone replacement therapy (HRT) is widely used to relieve symptoms of menopause with proven efficacy. However, there has been significant controversy surrounding the use of HRT because of its potential link with an increased risk of cancer, particularly female reproductive organ cancers. That HRT increases the risk of melanoma is also disputed, and several cohort studies have produced variable results. To delineate the association between HRT and melanoma in Taiwan, we conducted a population-based retrospective cohort study on 14 291 patients who had received HRT and 57 164 population controls in Taiwan between 2000 and 2013. Multivariate odds ratios (ORs) were calculated utilizing conditional logistic regression. Overall, the use of HRT was not significantly correlated with a higher risk of developing melanoma in Taiwan (95% confidence interval 0.386-1.099; p = 0.341). The hazard ratio analysis of melanoma and different HRTs showed there was no significant association between melanoma and the use of oral or external estrogens alone, including conjugated estrogens, estradiol, and estriol. Estrogen plus progesterone combined therapy was associated with a lower risk of melanoma. Only one case of melanoma was observed among the 2880 patients in this subgroup.

Risk of skin cancer in kidney, liver and heart recipients: A nationwide population-based study in Taiwan

Background

Previous population-based studies in western countries had revealed increased skin cancer risk among transplant recipients compared to the general population. However, population-based studies in Asia on skin cancer among recipients of different transplanted organs were lacking in the literature.

Aims

This study aims to estimate skin cancer risk among recipients in Taiwan, examine the association between each specific type of skin cancer and each type of transplanted organ, and compare skin cancer risk between different immunosuppressive regimens.

Methods

This population-based retrospective cohort study identified 7550 patients with heart, lung, kidney or liver transplantation and 30,200 controls matched for gender, age and comorbidity index from the National Health Insurance Research Database in Taiwan between 2000 and 2015. Using multivariable Cox proportional hazard models, we estimated the hazard ratios and 95% confidence intervals for the correlation of skin cancer with organ transplantation as well as immunosuppressive regimen.

Results

Organ transplant recipients in Taiwan had an increased risk of skin cancer with adjusted hazard ratios of 4.327 (95% confidence intervals 2.740-6.837, P < 0.001), with the greatest risk, observed among heart recipients (adjusted hazard ratios 6.348, 95% confidence intervals 3.080-13.088, P < 0.001). The risk of non-melanoma skin cancer and melanoma was 4.473 (95% confidence intervals 2.568-7.783, P < 0.001) and 3.324 (95% confidence intervals 1.300-8.172, P < 0.001), respectively. When comparing immunosuppressants, those with calcineurin inhibitors carried the highest risk of skin cancer (adjusted hazard ratios 4.789, 95% confidence intervals 3.033-7.569, P < 0.001), followed by those with antimetabolites (adjusted hazard ratios 4.771, 95% confidence intervals 3.025-7.541, P < 0.001).

Limitations

We could not evaluate confounding behavioural risk factors of skin cancers that were not documented in the database, nor could we recognize patients’ compliance with immunosuppressants.

Conclusion

Organ recipients have a greater risk of skin cancer. Clinicians should inform recipients of the importance of photoprotection and regular dermatologic follow-up.

Mechanisms of ultrasound-microbubble cavitation for inducing the permeability of human skin

We have previously reported that ultrasound (US)-mediated microbubble (MB) cavitation (US-MB) changed the permeability of the skin and significantly enhanced transdermal drug delivery (TDD) without changing the structure of the skin. In this study we found that US-MB enhanced TDD via disruption of epidermal cell-cell junctions and increased matriptase activity. Matriptase is a membrane-bound serine protease regulated by its inhibitor hepatocyte growth factor activator inhibitor-1 (HAI-1), and it is expressed in most epithelial tissues under physiologic conditions. Matriptase is expressed in mice after chronic exposure to UV radiation. This study found that US-MB can be used to monitor active matriptase, which rapidly formed the canonical 120-kDa matriptase-HAI-1 complex. These processes were observed in HaCaT human keratinocytes when matriptase activation was induced by US-MB. The results of immunoblot analysis indicated that the matriptase-HAI-1 complex can be detected from 10 min to 3 h after US-MB. Immunohistochemistry (IHC) of human skin revealed that US-MB rapidly increased the activated matriptase, which was observed in the basal layer, with this elevation lasting 3 h. After 3 h, the activated matriptase extended from the basal layer to the granular layer, and then gradually decayed from 6 to 12 h. Moreover, prostasin expression was observed in the epidermal granular layer to the spinous layer, and became more obvious in the granular layer after 3 h. Prostasin was also detected in the cytoplasm or on the cell membrane after 6 h. These results suggest that matriptase plays an important role in recovering from US-MB-induced epidermal cell-cell junction disruption within 6 h. US-MB is therefore a potentially effective method for noninvasive TDD in humans.

Clinician-created educational video for shared decision-making in the outpatient management of acne

Shared decision-making (SDM) provides patient-centered care. However, the limited consultation time was the main factor hindering the application. Patient education is crucial in the process of SDM. The use of visual aids as health education materials is an effective way to improve patients’ health literacy and medication adherence. This study aimed to determine the effectiveness of the clinician-created educational video of acne, accessed by patients during the waiting time, including knowledge level and satisfaction. This study was conducted in dermatology outpatient clinics and collected patient responses through electronic devices. During the waiting time, patients with acne would read educational pamphlets and complete the test first. Then, a clinician-created 8-minute educational video, as a patient decision aid (PDA), was accessed by patients using their own mobile smart devices, followed by a test and questionnaire about the satisfaction of the pamphlet and video. We enrolled 50 patients with acne, including 33 males and 17 females. The mean age is 25.55 ± 6.27 years old, ranging from 15 to 47 years old. About the patients’ knowledge, the test score improved significantly after watching the video (P < .001). The same findings were observed in the subgroup analysis of gender and different age groups. A higher proportion of patients preferred the educational video over the pamphlet in both genders and different age groups. All patients agreed with the video helped them to understand the educational information and impressed them more than reading pamphlets. The application of clinician-created educational videos in patient education seems to be an efficient solution to implement SDM in the daily clinical work. Besides, we could remind patients to watch the video anytime when they were not sure about the treatment choices, side effects, or the precautions of medications.

Stevens-Johnson syndrome and toxic epidermal necrolysis associated with increased risk of developing psychiatric disorders: A retrospective population-based cohort study in Taiwan

Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN) are life-threatening adverse reactions to drugs and psychological sequelae are also observed to follow the trauma of widespread epidermal necrolysis. To delineate the association between SJS and TEN, and psychiatric disorders, we conducted a retrospective population-based cohort study by including 212 patients diagnosed with first-time SJS or TEN in Taiwan between 2000 and 2013 and 669 population controls. Adjusted hazard ratios were calculated after adjusting for sex, age, comorbidity in the form of Charlson comorbidity index, and facility level of care. Overall, SJS or TEN was associated with an increased risk of developing psychiatric disorders including schizophrenia, major depressive disorder, mania, anxiety, and bipolar with an adjusted hazard ratio of 1.392 (95% CI, 1.192-1.625; p < 0.001). Particularly, the adjusted hazard ratios of psychiatric disorders were 1.290 (95% CI, 1.105-1.506; p < 0.001) for SJS and 1.855 (95% CI, 1.587-2.167; p < 0.001) for TEN.

Minoxidil-Coated Lysozyme-Shelled Microbubbes Combined With Ultrasound for the Enhancement of Hair Follicle Growth: Efficacy In Vitro and In Vivo

Lysozyme (Lyz) is an antimicrobial peptide, a safe adjunct, and it has been indicated that Lyz can promote vibrissae follicle growth by enhancing the hair-inductive capacity of dermal papilla cells in mice. The present study produced a new type of minoxidil (Mx)-coated antifungal Lyz-shelled microbubble (LyzMB) for inhibiting bacteria and allergies on the oily scalp. The potential of Mx-coated LyzMBs (Mx-LyzMBs) combined with ultrasound (US) and the role of LyzMB fragments in enhancing hair follicle growth were investigated. Mx grafted with LyzMBs were synthesized and the loading efficiency of Mx on cationic LyzMBs was 20.3%. The biological activity of Lyz in skin was determined using an activity assay kit and immunohistochemistry expression, and the activities in the US+Mx-LyzMBs group were 65.8 and 118.5 μU/mL at 6 and 18 h, respectively. In hair follicle cell culture experiments, the lengths of hair follicle cells were significantly enhanced in the US+Mx-LyzMBs group (108.2 ± 11.6 μm) compared to in the US+LyzMBs+Mx group (44.3 ± 9.8 μm) and the group with Mx alone (79.6 ± 12.0 μm) on day 2 (p < 0.001). During 21 days of treatment in animal experiments, the growth rates at days 10 and 14 in the US+Mx-LyzMBs group increased by 19.4 and 65.7%, respectively, and there were significant differences (p < 0.05) between the US+Mx-LyzMBs group and the other four groups. These findings indicate that 1-MHz US (applied at 3 W/cm², acoustic pressure = 0.266 MPa) for 1 min combined with Mx-LyzMBs can significantly increase more penetration of Mx and LyzMB fragments into skin and enhance hair growth than Mx alone.

Matriptase and prostasin proteolytic activities are differentially regulated in normal and wounded skin

Orchestrated control of multiple overlapping and sequential processes is required for the maintenance of epidermal homeostasis and the response to and recovery from a variety of skin insults. Previous studies indicate that membrane-associated serine protease matriptase and prostasin play essential roles in epidermal development, differentiation, and barrier formation. The control of proteolysis is a highly regulated process, which depends not only on gene expression but also on zymogen activation and the balance between protease and protease inhibitor. Subcellular localization can affect the accessibility of protease inhibitors to proteases and, thus, also represents an integral component of the control of proteolysis. To understand how membrane-associated proteolysis is regulated in human skin, these key aspects of matriptase and prostasin were determined in normal and injured human skin by immunohistochemistry. This staining shows that matriptase is expressed predominantly in the zymogen form at the periphery of basal and spinous keratinocytes, and prostasin appears to be constitutively activated at high levels in polarized organelle-like structures of the granular keratinocytes in the adjacent quiescent skin. The membrane-associated proteolysis appears to be elevated via an increase in matriptase zymogen activation and prostasin protein expression in areas of skin recovering from epidermal insults. There was no noticeable change observed in other regulatory aspects, including the expression and tissue distribution of their cognate inhibitors HAI-1 and HAI-2. This study reveals that the membrane-associated proteolysis may be a critical epidermal mechanism involved in responding to, and recovering from, damage to human skin.

Application of ultrasound-mediated adapalene-coated lysozyme-shelled microbubbles in UVA-induced skin photoaging

Photoaging, the premature aging of skin induced by ultraviolet rays, is characterized by wrinkling, roughness, laxity, and pigmentary changes. Various natural and synthetic retinoids have been explored for the treatment of aging. Among retinoids, adapalene (Ada, 0.3%) is one of the most potent and widely used drugs to treat photoaging. However, it causes irritant reactions that limit its acceptance by patients. Several studies have shown the applicability of Lysozyme (Lys)-shelled microbubbles (MBs) for drug delivery through sonophoresis, and recently we have shown its efficiency to treat inflammatory skin disease. Here, we report the construction of novel Ada-LysMBs based on opposite electric charges for combined effects to treat photoaging. The Ada-LysMBs were self-assembled and had a mean diameter of 2857 nm. The maximum loading efficiency of Ada onto LysMBs was 13.99 ± 0.59%. An acoustic power density of 3 W/cm2 for 1 min revealing maximum penetration depth of LysMBs was optimized for further in vitro and in vivo studies of Ada-LysMBs. It was observed that in vitro Ada release from Ada-LysMBs at 6 h after ultrasound (US) treatment was more rapid at pH 7.4 (82%) than at pH 5.5 (73%). Franz diffusion experiments on isolated porcine skin indicated that US approximately doubled Ada delivery by Ada-LysMBs and Ada + LysMBs at 12 h and six-fold Lys permeation by LysMBs at 6 h, compared to these treatments alone. A 5-week in vivo study in mice identified significant wrinkle reduction in animals treated with US plus Ada-LysMBs. Our findings indicate that US may be used with Ada-LysMBs in the water phase to treat photoaging by normalizing hyperkeratinization and promoting collagen synthesis.

Increased risk of dementia in patients with genital warts: A nationwide cohort study in Taiwan

Genital warts are a common sexually transmitted disease caused by human papillomavirus (HPV) infections. The prevalence of dementia is 4-8% in those aged 65 years or older in Taiwanese community studies, with a high social and economic burden for patients, family caregivers, the community and society. Previous studies have shown that viral infections such as herpes simplex and herpes zoster were associated with dementia. This study aimed to investigate the association between dementia and HPV infections. A population-based cohort study using data from Taiwan's National Health Insurance Research Database was conducted. Fine and Grays's survival analysis was employed to estimate the hazard ratios (HR) and 95% confidence intervals (CI) for the association between genital warts and dementia. From all of the potential participants aged 50 years or more, a total of 16 116 patients were enrolled, including 4029 genital warts-infected patients, with 12 087 sex-, age- and indexed date-matched controls (1:3). The cumulative incidences of dementia were 10.72 per 10³  person-years and 6.43 per 10³  person-years in the genital warts and control group, respectively. There were 475 dementia cases from the genital warts cohort during the follow-up period of 15 years. The adjusted HR for dementia was 1.485 (95% CI, 1.321-1.668; P < 0.001) for genital warts patients after adjusting for all of the covariates. Our study indicates that genital warts infection may increase the risk of dementia.

Arthropod Bite-Like Eruption as Rare Presentation of Secondary Syphilis in an HIV-Infected Patient

Secondary syphilis represents a diagnostic challenge due to its varied clinical manifestations. Co-infection with human immunodeficiency virus (HIV) adds to the diversity of the clinical presentation of syphilis. We herein report a case of secondary syphilis as an arthropod bite-like eruption in a previously undiagnosed HIV-coinfected patient. A 24-year-old homosexual male presented with multiple corticosteroid-resistant insect bite-like nodules on his trunk and bilateral arms. Skin biopsy disclosed plasma cell infiltration and positive Treponema pallidum staining. His symptoms got dramatic remission after benzathine penicillin G therapy. The presented case extends the clinical spectrum of secondary syphilis in HIV patient.

Increased risk of bullous pemphigoid in dipeptidyl peptidase 4 inhibitors: A nationwide, population-based, cohort study in Taiwan

Recent studies revealed the risk of bullous pemphigoid (BP) in patients with diabetes mellitus (DM) taking dipeptidyl peptidase 4 (DPP-4) inhibitors. To clarify the relationship between taking DPP-4 inhibitors and the risk of BP among patients with DM, we conducted a cohort study by using the National Health Insurance Research Database of Taiwan from 1 January 2009 to 31 December 2015. We identified 6340 patients with DM taking DPP-4 inhibitors and 25 360 DM patients who had not taken DPP-4 inhibitors during the 7-year follow-up period. Compared with the non-DPP-4 inhibitor group, patients taking DDP-4 inhibitors had a higher risk of BP (adjusted hazard ratio [aHR], 2.382; 95% confidence interval (CI), 1.163-4.883; P = 0.017]. Among the DPP-4 inhibitors available in Taiwan, vildagliptin showed the highest risk of BP (aHR, 2.849; 95% CI, 1.893-4.215; P < 0.001), followed by saxagliptin (aHR, 2.657; 95% CI, 1.770-3.934; P < 0.001). Subgroup analysis revealed that the higher risk of BP was observed in patients older than 65 years (aHR, 2.403; 95% CI, 1.590-3.627; P < 0.001). This study revealed that treatment with DPP-4 inhibitors, especially vildagliptin, was significantly associated with an increased risk of BP among DM patients.

Risk of psychiatric disorders in rosacea: A nationwide, population-based, cohort study in Taiwan

Rosacea has been reported to be associated with psychiatric disorders. Nevertheless, a nationwide study of the relationship between rosacea and comorbid psychiatric diseases in an Asian population has not been conducted. The aim of this study was to clarify the role of rosacea in the various psychiatric disorders by using a nationwide database in Taiwan. Data were obtained from the National Health Insurance Research Database of Taiwan from 2000 to 2013. In total, 7881 patients with rosacea and 31 524 age- and sex-matched controls were enrolled. Patients with rosacea tended to have more coexisting psychiatric disorders. After adjusting for age, sex, comorbidity and residence/regions, the adjusted hazard ratio (HR) of psychiatric disorders for patients with rosacea was 2.761 (95% CI = 2.650-2.877, P < 0.001). Among them, the highest adjusted HR are phobic disorder and obsessive-compulsive disorder of 7.841 (95% CI = 7.526-8.170, P < 0.001) and 6.389 (95% CI = 6.132-6.657, P < 0.001), respectively. The National Health Insurance Research Database of Taiwan does not include the information about rosacea subtypes, severity and laboratory parameters. In conclusion, rosacea is related to various psychiatric disorders. In addition to anxiety and depression, patients are also at increased risk of phobic disorder and obsessive-compulsive disorder.

Ultrasound-Mediated EGF-Coated-Microbubble Cavitation in Dressings for Wound-Healing Applications

The feasibility of ultrasound (US) controlled cavitation for transdermal drug delivery (TDD) using gas-filled microbubbles (MBs) has been explored. However, liquid or gel-type MBs is not easy used for TDD. The present study investigated a new treatment model for evaluating the US-mediated liquid-type epidermal growth factor (EGF)-coated lysozyme microbubble (LYMB) cavitation in a wound dressing for enhancing wound healing. The maximum loading efficacy of EGF onto LYMBs was 19.40 ± 0.04%. In terms of the in vitro treatment efficacy, the growth of Staphylococcus aureus was inhibited by 97.50 ± 1.50% in the group with LYMBs exposed to 3 W/cm² US. During 21 days in vivo wound healing experiments, the recovery rate during the first 6 days was significant higher in the group with EGF-LYMB dressings and US exposure (day 6: 54.28 ± 3.26%) than in the control group (day 6: 26.36 ± 3.34%) (p < 0.05). Our results show that the new model can significantly reduce the treatment duration during wound healing.

Anti-herpetic Medications and Reduced Risk of Dementia in Patients with Herpes Simplex Virus Infections-a Nationwide, Population-Based Cohort Study in Taiwan

This retrospective cohort study is to investigate the association between herpes simplex virus (HSV) infections and dementia, and the effects of anti-herpetic medications on the risk involved, using Taiwan's National Health Insurance Research Database (NHIRD). We enrolled a total of 33,448 subjects, and identified 8362 with newly diagnosed HSV infections and 25,086 randomly selected sex- and age-matched controls without HSV infections in a ratio of 1:3, selected from January 1, to December 31, 2000. A multivariable Cox proportional hazards regression model was used to evaluate the risk of developing dementia in the HSV cohort. This analysis revealed an adjusted hazard ratio of 2.564 (95% CI: 2.351-2.795, P < 0.001) for the development of dementia in the HSV-infected cohort relative to the non-HSV cohort. Thus, patients with HSV infections may have a 2.56-fold increased risk of developing dementia. A risk reduction of dementia development in patients affected by HSV infections was found upon treatment with anti-herpetic medications (adjusted HR = 0.092 [95% CI 0.079-0.108], P < 0.001). The usage of anti-herpetic medications in the treatment of HSV infections was associated with a decreased risk of dementia. These findings could be a signal to clinicians caring for patients with HSV infections. Further research is, therefore, necessary to explore the underlying mechanism(s) of these associations.

Tissue distribution and subcellular localizations determine in vivo functional relationship among prostasin, matriptase, HAI-1, and HAI-2 in human skin

The membrane-bound serine proteases prostasin and matriptase and the Kunitz-type protease inhibitors HAI-1 and HAI-2 are all expressed in human skin and may form a tightly regulated proteolysis network, contributing to skin pathophysiology. Evidence from other systems, however, suggests that the relationship between matriptase and prostasin and between the proteases and the inhibitors can be context-dependent. In this study the in vivo zymogen activation and protease inhibition status of matriptase and prostasin were investigated in the human skin. Immunohistochemistry detected high levels of activated prostasin in the granular layer, but only low levels of activated matriptase restricted to the basal layer. Immunoblot analysis of foreskin lysates confirmed this in vivo zymogen activation status and further revealed that HAI-1 but not HAI-2 is the prominent inhibitor for prostasin and matriptase in skin. The zymogen activation status and location of the proteases does not support a close functional relation between matriptase and prostasin in the human skin. The limited role for HAI-2 in the inhibition of matriptase and prostasin is the result of its primarily intracellular localization in basal and spinous layer keratinocytes, which probably prevents the Kunitz inhibitor from interacting with active prostasin or matriptase. In contrast, the cell surface expression of HAI-1 in all viable epidermal layers renders it an effective regulator for matriptase and prostasin. Collectively, our study suggests the importance of tissue distribution and subcellular localization in the functional relationship between proteases and protease inhibitors.

Loss of GPNMB Causes Autosomal-Recessive Amyloidosis Cutis Dyschromica in Humans

Amyloidosis cutis dyschromica (ACD) is a distinct form of primary cutaneous amyloidosis characterized by generalized hyperpigmentation mottled with small hypopigmented macules on the trunks and limbs. Affected families and sporadic case subjects have been reported predominantly in East and Southeast Asian ethnicities; however, the genetic cause has not been elucidated. We report here that the compound heterozygosity or homozygosity of GPNMB truncating alleles is the cause of autosomal-recessive ACD. Six nonsense or frameshift mutations were identified in nine individuals diagnosed with ACD. Immunofluorescence analysis of skin biopsies showed that GPNMB is expressed in all epidermal cells, with the highest staining observed in melanocytes. GPNMB staining is significantly reduced in the lesional skin of affected individuals. Hyperpigmented lesions exhibited significantly increased amounts of DNA/keratin-positive amyloid deposits in the papillary dermis and infiltrating macrophages compared with hypo- or depigmented macules. Depigmentation of the lesions was attributable to loss of melanocytes. Intracytoplasmic fibrillary aggregates were observed in keratinocytes scattered in the lesional epidermis. Thus, our analysis indicates that loss of GPNMB, which has been implicated in melanosome formation, autophagy, phagocytosis, tissue repair, and negative regulation of inflammation, underlies autosomal-recessive ACD and provides insights into the etiology of amyloidosis and pigment dyschromia.

Ethanol oxidation and the inhibition by drugs in human liver, stomach and small intestine: Quantitative assessment with numerical organ modeling of alcohol dehydrogenase isozymes

Alcohol dehydrogenase (ADH) is the principal enzyme responsible for metabolism of ethanol. Human ADH constitutes a complex isozyme family with striking variations in kinetic function and tissue distribution. Liver and gastrointestinal tract are the major sites for first-pass metabolism (FPM). Their relative contributions to alcohol FPM and degrees of the inhibitions by aspirin and its metabolite salicylate, acetaminophen and cimetidine remain controversial. To address this issue, mathematical organ modeling of ethanol-oxidizing activities in target tissues and that of the ethanol-drug interactions were constructed by linear combination of the corresponding numerical rate equations of tissue constituent ADH isozymes with the documented isozyme protein contents, kinetic parameters for ethanol oxidation and the drug inhibitions of ADH isozymes/allozymes that were determined in 0.1 M sodium phosphate at pH 7.5 and 25 °C containing 0.5 mM NAD(+). The organ simulations reveal that the ADH activities in mucosae of the stomach, duodenum and jejunum with ADH1C*1/*1 genotype are less than 1%, respectively, that of the ADH1B*1/*1-ADH1C*1/*1 liver at 1-200 mM ethanol, indicating that liver is major site of the FPM. The apparent hepatic KM and Vmax for ethanol oxidation are simulated to be 0.093 ± 0.019 mM and 4.0 ± 0.1 mmol/min, respectively. At 95% clearance in liver, the logarithmic average sinusoidal ethanol concentration is determined to be 0.80 mM in accordance with the flow-limited gradient perfusion model. The organ simulations indicate that higher therapeutic acetaminophen (0.5 mM) inhibits 16% of ADH1B*1/*1 hepatic ADH activity at 2-20 mM ethanol and that therapeutic salicylate (1.5 mM) inhibits 30-31% of the ADH1B*2/*2 activity, suggesting potential significant inhibitions of ethanol FPM in these allelotypes. The result provides systematic evaluations and predictions by computer simulation on potential ethanol FPM in target tissues and hepatic ethanol-drug interactions in the context of tissue ADH isozymes.

Nitric oxide suppresses LPS-induced inflammation in a mouse asthma model by attenuating the interaction of IKK and Hsp90

A feature of allergic airway disease is the observed increase of nitric oxide (NO) in exhaled breath. Gram-negative bacterial infections have also been linked with asthma exacerbations. However, the role of NO in asthma exacerbations with gram-negative bacterial infections is still unclear. In this study, we examined the role of NO in lipopolysaccharide (LPS)-induced inflammation in an ovalbumin (OVA)-challenged mouse asthma model. To determine whether NO affected the LPS-induced response, a NO donor (S-nitroso-N-acetylpenicillamine, SNAP) or a selective inhibitor of NO synthase (1400W) was injected intraperitoneally into the mice before the LPS stimulation. Decreased levels of proinflammatory cytokines were demonstrated in the bronchoalveolar lavage fluid from mice treated with SNAP, whereas increased levels of cytokines were found in the 1400W-treated mice. To further explore the molecular mechanism of NO-mediated inhibition of proinflammatory responses in macrophages, RAW 264.7 cells were treated with 1400W or SNAP before LPS stimulation. LPS-induced inflammation in the cells was attenuated by the presence of NO. The LPS-induced IκB kinase (IKK) activation and the expression of IKK were reduced by NO through attenuation of the interaction between Hsp90 and IKK in the cells. The IKK decrease in the lung immunohistopathology was verified in SNAP-treated asthma mice, whereas IKK increased in the 1400W-treated group. We report for the first time that NO attenuates the interaction between Hsp90 and IKK, decreasing the stability of IKK and causing the down-regulation of the proinflammatory response. Furthermore, the results suggest that NO may repress LPS-stimulated innate immunity to promote pulmonary bacterial infection in asthma patients.

Human mitochondrial NAD(P)(+)-dependent malic enzyme participates in cutaneous melanoma progression and invasion

Cutaneous melanoma is the most life-threatening neoplasm of the skin, accounting for most of the skin cancer deaths. Accumulating evidence suggests that targeting metabolism is an appealing strategy for melanoma therapy. Mitochondrial NAD(P)(+)-dependent malic enzyme (ME2), an oxidative decarboxylase, was evaluated for its biological significance in cutaneous melanoma progression. ME2 mRNA and protein expression significantly increased during melanoma progression, as evidenced by Gene Expression Omnibus analysis and immunohistochemistry on clinically annotated tissue microarrays, respectively. In addition, ME2 knockdown attenuated melanoma cell proliferation in vitro. ME2 ablation resulted in reduced cellular ATP levels and elevated cellular reactive oxygen species production, which activated the AMP-activated protein kinase pathway and inhibited acetyl-CoA carboxylase. Furthermore, ME2 expression was associated with cell migration and invasion. ME2 knockdown decreased anchorage-independent growth in vitro and tumor cell growth in vivo. These results suggested that ME2 might be an important factor in melanoma progression and a novel biomarker of invasion.

Dominance of the inactive Asian variant over activity and protein contents of mitochondrial aldehyde dehydrogenase 2 in human liver

BACKGROUND

It has been well documented that a variant allele of mitochondrial aldehyde dehydrogenase 2 (ALDH2), ALDH2*2, commonly occurs in East Asians but rarely in other ethnic populations. This unique allelic variation significantly influences drinking behavior and susceptibility to development of alcoholism. Previous structural, functional, and cellular studies indicate that the resulting variant polypeptide subunit K (Lys-487) exerts dominance of null activity and shorter half-life over the tetrameric enzyme molecules in distinct manners. However, the in vivo evidence for the proposed dominance mechanisms remains lacking.

METHODS

To address this question, we investigated 33 surgical liver samples identified to be normal homozygous ALDH2*1/*1 (n = 17), heterozygous ALDH2*1/*2 (n = 13), and variant homozygous ALDH2*2/*2 (n = 3). The ALDH2 activity was determined at a sufficient low acetaldehyde concentration (3 μM) and the isozyme protein amount by immunotitration using purified class-specific antibodies.

RESULTS

The tissue ALDH2 activity in heterozygotes was 17% that of the ALDH2*1/*1 genotype (p < 0.001), whereas the activity of ALDH2*2/*2 was too low to be precisely determined. The protein amounts of tissue ALDH2 in variant homozygotes and heterozygotes were similar but only 30 to 40% that of normal homozygotes (p < 0.01). Linear regression analyses show that ALDH2 activities were significantly correlated with the protein contents in normal homozygotes and heterozygotes, respectively (p < 0.005). The specific activity of ALDH2 per enzyme protein in ALDH2*1/*2 was 38% that of ALDH2*1/*1 (p < 0.001).

CONCLUSIONS

These results are in good agreement with those predicted by the model studies, thus providing in vivo evidence for differential impairments of hepatic acetaldehyde oxidation with alcohol metabolism in individuals carrying ALDH2*1/*2 and ALDH2*2/*2 genotypes.