Impact of economic shocks on mental health during COVID-19: A longitudinal study of adult residents of Indian metropolitan cities.

Background: The causal impact of income shocks on mental well-being in developing countries is an under-researched area. The COVID-19 pandemic, along with the economic recession caused by the lockdowns to reduce transmission, provides a natural experimental setting to examine the causal impact of a decline in monthly per capita expenditure (MPCE) on mental health of the general population in India during the pandemic. Aim: To evaluate the impact of income shocks on mental health of adults in metro cities during the COVID-19 pandemic. Materials and Methods: The data were collected using the abridged version of the Depression Anxiety Stress Schedule administered through a telephonic survey on adult residents of six metropolitan cities in September-August 2020 and July-August 2021. Results: In the present study, 994 adults participated from six metropolitan cities. Average treatment effects were estimated using Propensity Score Matching. The mean normalized scores are significantly higher for respondents whose MPCE had fallen (treated) vis-à-vis respondents whose MPCE had remained same or increased (control): anxiety (0.21 for treated vs -0.19 for control), stress (0.16 vs -0.14), and depression (0.04 vs -0.19). Propensity score matching reveals that the normalized scores for anxiety, stress, and depression were 33 (95% confidence intervals, CI: 20.0-46.7), 25 (95% CI: 12.9-36.9), and 36 (95% CI: 18.6-53.1) higher among the treated group vis-a-vis control group. The ATET was 34 (95% CI: 18.9-48.9), 26 (95% CI: 10.1-42.9), and 32 (955 CI: 12.3-50.7) for these three outcomes, respectively. The post-estimation tests indicated that the results are valid. Conclusions: The study advocates that policies to ensure income security should be made an integral part of the response packages to tackle pandemics like COVID-19.

Change in mental health during the COVID-19 pandemic: a longitudinal study of residents of Indian metropolitan cities.

BACKGROUND: Initial studies have reported an increase in the incidence of mental health problems during the early months of COVID-19. Longitudinal studies of changes in mental health undertaken in Low and Middle Income countries during the pandemic remains an under-researched area. AIMS: The current study examines changes in mental health among adult residents of metropolitan cities of India, a middle-income country reporting the second-highest COVID cases and third-highest fatalities, during the pandemic. METHOD: Data was collected, based on a telephonic survey using the internationally accepted abridged Depression Anxiety Stress schedule (DASS-21), in August and September 2020 and July-August 2021. The sample size is 994. The data was analysed using an ordered logit model. RESULTS: At the onset of the pandemic, high levels of anxiety, stress and depression prevailed; their levels reduced after one year. Respondents who have experienced a decline in economic fortunes, have family members with pre-existing co-morbidity or had COVID in the family are significantly less likely to report improvement in mental health; less-educated respondents are also vulnerable. CONCLUSIONS: Specific sub-groups, identified as at risk, need monitoring and continued provisioning of tailor-made mental health services addressing their specific needs. Relief measures targeting economically affected households are also required.

Changes in dietary practices of mother and child during the COVID-19 lockdown: Results from a household survey in Bihar, India.

The outbreak of COVID-19, and the national-level lockdown to contain it, were expected to disrupt supply chains, lead to livelihood loss, and reduce household income. Studies anticipated a decline in food security in India, leading to a near famine-like situation. In this study, we examine the change in Dietary Score (number of food groups consumed out of a possible eight) and proportion of respondents complying with Minimum Dietary Diversity norms (consuming at least four food groups) among women aged 15-49 years and their youngest child (aged between 7 and 36 months) during the lockdown. The present study also analyses whether ownership of ration cards and contacts with the party in power locally helped the household to tide over the crisis. The data was collected through a two-phase primary survey undertaken in January-March 2020 (pre-lockdown period) and October-November 2020 (post-lockdown period). It was undertaken in six districts of Bihar, a state with a history of poor maternal and child health outcomes and dysfunctional delivery of health services. We find that dietary practices of women deteriorated, while that of children remained the same. The deterioration is less among households owning ration cards or having political contacts. The analysis suggests that, during pandemics or similar crisis periods, the need to supplement the supply of staple items through the Public Distribution System with a direct transfer of cash will allow households to maintain diversity in the consumption basket.

Is consanguineous marriage related to spousal violence in India? Evidence from the National Family Health Survey, 2015-16.

Violence against women is a global phenomenon, and intimate partner violence is the most common form of violence faced by women in the world. Around 30% of women in the world, on average, and 33% in India experience intimate partner violence during their lifetime. The main aim of this study was to investigate whether consanguinity protects women from spousal violence. National Family Health Survey 2015-16 (NFHS-4) data were used. The study sample comprised 60,824 currently married women aged 15-49 years. The results of the logistic regression model showed that the likelihood of all types of spousal violence against women was higher among consanguineous unions compared with non-consanguineous unions in India. The association between consanguineous marriage and spousal violence was found to be positive and significant in the southern and eastern regions of India and among Scheduled Castes and Scheduled Tribes. The association was not significant among Muslims. Differences in socio-cultural norms and practices across the regions of India, and among different socio-cultural groups, can perhaps explain these variations. Women belonging in higher age groups, from Other Backward Castes, those who were working and those with a low level of educational attainment and socioeconomic standing had a higher risk of experiencing intimate partner violence. Couples in a consanguineous marriage should be given adequate counselling to reduce intimate partner violence in India, and similarly culturally diverse countries. This would also help reach Target 5.2 of the Sustainable Development Goals by 2030.

Change in the Prevalence and Determinants of Consanguineous Marriages in India Between National Family and Health Surveys of 1992-1993 and 2015-2016.

This study aimed to determine the changing prevalence of consanguineous marriage in India between two national-level surveys. The primary hypothesis was whether region of residence and religious affiliation continue to play a significant role in determining consanguineous marriage even after controlling other potentially significant confounding variables. Data from the 81,781 and 85,851 ever-married women during the National Family and Health Surveys (NFHS) survey periods 1992-1993 (NFHS-1) and 2015-2016 (NFHS-4), respectively, were used in the analysis. Multinomial and binary logistic regression analyses examined determinants of consanguineous marriage types and of paternal and maternal first-cousin marriages, respectively. In both analyses a systematic model-building procedure was adopted. Altogether, four models were estimated. In the final model (model 4) of both the analyses, all respondent background characteristics (region of residence, religious affiliation, sociodemographic, household wealth) and years of survey were included. Although the overall prevalence of consanguineous marriage in India declined significantly (16%), it was not uniform across respondent background characteristics. The northern region of India (154%) showed a significant increase in consanguineous marriage, whereas eastern (31%), central (2.3%), northeastern (40%), and southern (8%) regions showed a significant decline. Significant declines in consanguineous marriage were found for Hindus (16%) and Muslims (29%); for Muslims of eastern (48%), central (29%), western (31%), and southern (27%) regions; and for Hindus in the western region (37%). Relative risk ratios estimated using multinomial logistic regression models suggest those living in the southern region show 9.55 (p < 0.001), 5.96 (p < 0.001), and 38.16 (p < 0.001) times more likelihood in the prevalence of first-cousin, second-cousin, and uncle-niece marriages, respectively, compared to the northern region after controlling all other confounding variables. Muslims also showed 3.76 (p < 0.001) and 2.91 (p < 0.001) times more likelihood in first-cousin and second-cousin marriages, respectively, compared to Hindus. Adjusted odds ratios (AORs) estimated using binary logistic regression models suggest those living in southern and northeastern regions were 1.25 (p < 0.001) and 1.36 (p < 0.05) times more likely, respectively, to marry a maternal first cousin compared to the northern region. The AOR estimates also show that Muslims were 1.11 (p < 0.01) times more likely to marry a maternal first cousin compared to Hindus. The authors conclude that, despite significant development in the socioeconomic condition of India during the postglobalization era (beginning in 1992-1993), region of residence and religious affiliation continue to play significant role in determining consanguineous marriage.

Prevalence and determinants of consanguineous marriage and its types in India: evidence from the National Family Health Survey, 2015-2016.

The aim of the present study was to estimate the prevalence and examine the determinants of consanguineous marriage types in India. Data for 456,646 ever-married women aged 15-49 years were analysed from the National Family Health Survey (NFHS)-4 conducted in 2015-16. The overall prevalence of consanguineous marriage was 9.9%; the South region (23%) and North-East region (3.1%) showed the highest and lowest prevalences, respectively. Muslims had a higher prevalence (15%) than Hindus (9%). The prevalence of first cousin marriage (8.7%) was more than that of second cousin (0.7%) and of uncle-niece marriages (0.6%). Women living in urban areas and in nuclear families, having a higher level of education and belonging to affluent families were less likely to marry their cousins (p < 0.01). Women living in the South region of the country were more likely to marry their cousins, as well as uncles (p < 0.001). Close scrutiny of the trends in the results (odds ratios) revealed no clear relationship between socioeconomic condition and consanguineous marriage. The study results suggest that religion and north-south regional dichotomy in culture largely determine consanguineous marriage rather than socioeconomic condition in India.

Deciphering disparities in childhood stunting in an underdeveloped state of India: an investigation applying the unconditional quantile regression method.

BACKGROUND: Unacceptably high rate of childhood stunting for decades remained a puzzle in the eastern Indian state of Bihar. Despite various programmatic interventions, nearly half of the under-five children (numerically about 10 million) are still stunted in this resource-constrained state. DATA AND METHODS: Using four successive rounds of National Family Health Survey (NFHS) data spread over more than two decades and by employing unconditional quantile regressions and counterfactual decomposition (QR-CD), the present study aims to assess effects of various endowments as well as returns to those endowments in disparities in childhood stunting over the period. RESULTS: The results show that although the child's height-for-age Z-scores (HAZ) disparity largely accounted for differing levels of endowments during the earlier decades, in the later periods, inadequate access to the benefits from various development programmes was also found responsible for HAZ disparities. Moreover, effects of endowments and their returns varied across quantiles. We argue that apart from equalizing endowments, ensuring adequate access to different nutrition-centric programmes is essential to lessen the burden of childhood stunting. CONCLUSION: The state must focus on intersectoral convergence of different schemes in the form of state nutrition mission, and, strengthen nutrition-centric policy processes and their political underpinnings to harness better dividend.

ROLE OF COMMUNITY AND CONTEXT IN CONTRACEPTIVE BEHAVIOUR IN RURAL WEST BENGAL, INDIA: A MULTILEVEL MULTINOMIAL APPROACH.

Studies examining the influence of community-level interactions and contextual/supply-side factors in determining contraceptive choices have yielded mixed results in the context of rural India. Using small-scale survey data of 1348 women from rural West Bengal and by employing multilevel multinomial logit models, this study tested the influence of these factors after controlling for various socio-demographic and individual-level socioeconomic factors. The study reveals that supply-side intervention strategies, i.e. addressing outreach and advocacy activities and socio-religious needs at the community level, are essential prerequisites to breaking away from the predominance of sterilization in the contraceptive method-mix and enhancing the adoption of modern reversible contraceptives for improved spacing of births - a crucial factor in maternal and child health outcomes.

Sex differences in the risk profile of hypertension: a cross-sectional study.

OBJECTIVE: To assess the socioeconomic and behavioural risk factors associated with hypertension among a sample male and female population in India. SETTING: Cross-sectional survey data from a Health and Demographic Surveillance System (HDSS) of rural West Bengal, India was used. PARTICIPANTS: 27 589 adult individuals (13 994 males and 13 595 females), aged ≥18 years, were included in the study. PRIMARY AND SECONDARY OUTCOME MEASURES: Hypertension was defined as mean systolic blood pressure (SBP) ≥140 mm Hg or diastolic blood pressure (DBP) ≥90 mm Hg, or if the subject was undergoing regular antihypertensive therapy. Prehypertension was defined as SBP 120-139 mm Hg and DBP 80-89 mm Hg. Individuals were categorised as non-normotensives, which includes both the prehypertensives and hypertensives. Generalised ordered logit model (GOLM) was deployed to fulfil the study objective. RESULTS: Over 39% of the men and 25% of the women were prehypertensives. Almost 12.5% of the men and 11.3% of the women were diagnosed as hypertensives. Women were less likely to be non-normotensive compared to males. Odds ratios estimated from GOLM indicate that women were less likely to be hypertensive or prehypertensive, and age (OR 1.04, 95% CI 1.03 to 1.05; and OR 1.08, 95% CI 1.07 to 1.09 for males and females, respectively) and body mass index (OR 1.64, 95% CI 1.38 to 1.97 for males; and OR 1.32, 95% CI 1.08 to 1.60 for females) are associated with hypertension. CONCLUSIONS: An elevated level of hypertension exists among a select group of the rural Indian population. Focusing on men, an intervention could be designed for lifestyle modification to curb the prevalence of hypertension.

Effect of Sequential Intravenous Pulse Cyclophosphamide-Azathioprine in Systemic Sclerosis-Interstitial Lung Disease: An Open-Label Study.

BACKGROUND: Systemic sclerosis (SSc) is a rare connective tissue disorder of unknown aetiology. Pulmonary involvement contributes substantially to its morbidity and mortality. Treatment of pulmonary disease due to SSc remains unsatisfactory. We examined the effect of sequential six-month intravenous pulse therapy with cyclophosphamide (CYC) followed by azathioprine and low-dose corticosteroids on SSc associated interstitial lung disease (SSc-ILD). METHODS: In a single-centre, prospective, observational, open-labelled study; nine patients (eight females, one male) with SSc-ILD were treated with intravenous pulse CYC (600mg/m(2) body surface area) at monthly interval for six cycles with oral prednisolone 10mg daily. Subsequently, azathioprine (2-3mg/Kg) was administered while continuing with the same dose of prednisolone. Primary end-points were forced vital capacity (FVC) and high resolution computed tomography (HRCT) scan of thorax score. Secondary end-points were quality of life measured by health assessment questionnaire-disability index (HAQ-DI) and six-minute walk distance (6WMD) test. RESULTS: After one year of observation, the FVC showed significant improvement (p=0.003). The 6WMD also improved significantly (p=0.0028). However, change in HRCT scan scoring and HAQ-DI score was not significant. CONCLUSIONS: Intravenous, pulse CYC followed by azathioprine along with low-dose corticosteroids produces significant improvement in FVC and 6WMD at 12-month follow-up without significant change in radiological manifestations and health status.

Isolated Endobronchial Capillary Haemangioma: A Rare Cause of Haemoptysis in Adult.

Endobronchial capillary haemangioma is a very rare benign tumour in adults. The clinical presentation and management of adult capillary haemangiomas involving the tracheo-bronchial tree is not yet established. We present a case of an isolated capillary haemangioma of the left main bronchus detected during the evaluation of an adult male presented with haemoptysis. The lesion was managed successfully bronchoscopically.

Determinants of Skilled Delivery Assistance in a Rural Population: Findings from an HDSS Site of Rural West Bengal, India.

OBJECTIVE: This study examines the determinants of utilisation of skilled birth attendants (SBAs) amongst 2886 rural women in the state of West Bengal, India, using data from a survey of 2012-2013 conducted by the Birbhum Health and Demographic Surveillance System. METHOD: Multilevel logit regression models were estimated and qualitative investigations conducted to understand the determinants of utilisation of SBAs in rural West Bengal. RESULTS: Among women who delivered their last child during the 3 years preceding the survey, 69.1 % of deliveries were assisted by SBAs, while 30.9 % were home deliveries without any SBA assistance. Multivariate analysis revealed that apart from socio-demographic and economic factors (such as household affluence, women's education, birth order, uptake of comprehensive ANC check-ups, advice regarding danger signs of pregnancy and household's socio-religious affiliation), supply side factors, such as availability of skilled birth attendants in the village and all-weather roads, have significant effect on seeking skilled assistance. Our findings also show that unobserved factors at village level independently influence uptake of SBA-assisted delivery. CONCLUSIONS FOR PRACTICE: The present findings emphasise that both demand and supply side intervention strategies are essential prerequisites to enhance skilled birth attendance. Ample communication is observed at the individual level, but improving community level outreach and advocacy activities could generate further demand. SBAs can be better integrated by accommodating the socio-religious needs of local communities, such as providing female doctors and doctors with similar socio-religious backgrounds.

Rare Endobronchial metastasis from uterine leiomyosarcoma.

Uterine sarcomas are rare and represent approximately 3.2% of all invasive uterine cancers. The annual incidence rate is less than two per 100,000 women. The median age at which uterine sarcoma diagnosed is 56 years. The most common histologic pattern is leiomyosarcoma (LMS) which originates from the myometrium or myometrial vessels. Uterine LMSs are aggressive tumors with high rates of recurrence. The most common mode of spread is hematogenous, with lymphatic spread being rare. Recurrences of up to 70% are reported in stage I and II disease with the site of recurrence being distal, most commonly the lungs or the upper abdomen. But the intra bronchial spread is extremely rare. Here we are reporting a case of uterine LMS with endobronchial metastasis causing whole lung collapse.

Health & Demographic Surveillance System Profile: The Birbhum population project (Birbhum HDSS).

The Birbhum HDSS was established in 2008 and covers 351 villages in four administrative blocks in rural areas of Birbhum district of West Bengal, India. The project currently follows 54 585 individuals living in 12557 households. The population being followed up is economically underprivileged and socially marginalized. The HDSS, a prospective longitudinal cohort study, has been designed to study changes in population demographic, health and healthcare utilization. In addition to collecting data on vital statistics and antenatal and postnatal tracking, verbal autopsies are being performed. Moreover, periodic surveys capturing socio-demographic and economic conditions have been conducted twice. Data on nutritional status (children as well as adults), non-communicable diseases, smoking etc. have also been collected in special surveys. Currently, intervention studies on anaemia, undernutrition and common preschool childhood morbidities through behavioural changes are under way. For access to the data, a researcher needs to send a request to the Data Manager [suri.shds@gmail.com]. Data are shared in common formats like comma-separated files (csv) or Microsoft Excel (xlsx) or Microsoft Access Database (mdb).The HDSS will soon upgrade its data management system to a more integrated platform, coordinated and guided by INDEPTH data sharing policy.

Is health status of elderly worsening in India? A comparison of successive rounds of national sample survey data.

The increasing greying of India's population raises concerns about the welfare and health status of the aged. One important source of information of health status of the elderly is the National Sample Survey Rounds on Morbidity and Health Care Expenditure. Using unit-level data for 1995-96 and 2004, this paper examines changes in reported health status of the elderly in India and analyses their relationship with living arrangements and extent of economic dependency. It appears that even after controlling for factors like caste, education, age, economic status and place of residence, there has been a deterioration in self-perceived current health status of the elderly. The paper argues that, although there have been changes in the economic condition and traditional living arrangements--with a decline in co-residential arrangements--this is not enough to explain the decline in reported health status and calls for a closer look at narratives of neglect being voiced in developing countries.

Exploring socioeconomic vulnerability of anaemia among women in eastern Indian States.

The present study investigates the socioeconomic risk factors of anaemia among women belonging to eastern Indian states. An attempt has been made to find out differences in anaemia related to social class and place of residence, and age and marital status. It was hypothesized that rural women would have a higher prevalence of anaemia compared with their urban counterparts, particularly among the poorest social strata, and that ever-married women would be at elevated risk of anaemia compared with never-married women, particularly in the adolescent age group. Using data from National Family Health Survey-3, 2005-6, a nationally representative cross-sectional survey that provided information on anaemia level among 19,695 women of this region, the present study found that the prevalence of anaemia was high among all women cutting across social class, location and other attributes. In all 47.9% were mildly anaemic (10.0-11.9.9 g/dl), 16.1% were moderately anaemic (7.0-9.9 g/dl) and 1.6% were severely anaemic (<7.0 g/dl). Protective factors include frequent consumption of pulses, milk and milk products, fruits and fish, educational attainment, mass media exposure and high socioeconomic status. Urban poor women and adolescent ever-married women had very high odds of being anaemic. New programme strategies are needed, particularly those that improve iron storage and enhance the overall nutritional status of women throughout the life-cycle.

Visualization and quantification of skin barrier perturbation induced by surfactant-humectant systems using two-photon fluorescence microscopy.

In order to visualize the effects of aqueous surfactant-humectant systems on the skin barrier, an in vitro two-photon fluorescence microscopy (TPM) study, including dual-channel visualization, was carried out. TPM is a non-invasive imaging technique based on two-photon induced nonlinear excitations of fluorophores, with the capability for deep-tissue imaging (up to several hundred micrometers). The following aqueous solutions of surfactants, a humectant, and a surfactant+humectant mixture that contacted pig full-thickness skin (p-FTS) were studied: (i) a harsh surfactant solution-sodium dodecyl sulfate (SDS) (1 wt%); (ii) a harsh surfactant+humectant solution-SDS (1 wt%) + glycerol (10 wt%); (iii) a mild surfactant solution-sodium cocoyl isethionate (SCI) (1 wt%); (iv) a control solution-phosphate-buffered saline (PBS); and (v) a humectant solution-glycerol (10 wt%). Sulforhodamine B (SRB), a hydrophilic fluorescent probe, was used to visualize the effects of aqueous contacting solutions i-v on the skin barrier morphology. The results of the TPM visualization study revealed that SDS induces corneocyte damage by denaturing keratins and creating intracorneocyte penetration pathways. On the other hand, SDS+glycerol did not significantly induce corneocyte damage. The dual-channel TPM images corresponding to aqueous contacting solutions iii-v showed low SRB penetration into the corneocytes, as well as localization of the SRB probe within the lipid bilayers surrounding the corneocytes of the SC. Through a quantification of the amount of SRB that penetrated into the skin as a function of skin depth, we found that adding glycerol to an SDS aqueous contacting solution can significantly reduce the SDS-induced penetration depth of SRB, which provides evidence of the ability of glycerol to mitigate SDS-induced skin barrier perturbation. The distribution of SRB in the p-FTS samples was analyzed using a theoretical model that quantified changes in the skin aqueous pore characteristics induced by aqueous contacting solutions i, ii, iii, and v, relative to aqueous contacting solution iv, the control. The results of the theoretical model indicate the following ranking order in the extent of perturbation to the skin aqueous pores (from the highest to the lowest): i > ii > iii > iv > v. The development of such an in vitro visual ranking methodology, including quantification using TPM, can potentially reduce many costly in vivo screening procedures, thereby significantly reducing the cost and time-to-market of new cosmetic formulations containing surfactants and humectants.

Why is sodium cocoyl isethionate (SCI) mild to the skin barrier? - An in vitro investigation based on the relative sizes of the SCI micelles and the skin aqueous pores.

Sodium cocoyl isethionate (SCI) is an important surfactant ingredient in mild, syndet (synthetic detergent) cleansing bars. In vitro and in vivo studies have demonstrated that SCI is mild and less damaging to the skin barrier than soaps and surfactants such as sodium dodecyl sulfate (SDS). We have recently shown that SDS forms small micelles in aqueous solutions contacting the skin relative to the aqueous pores in the stratum corneum (SC), and as a result, the SDS micelles can contribute to SDS skin penetration and induce skin barrier perturbation. In this paper, we attempt to explain the well-documented skin mildness of SCI by examining the size of the SCI micelles relative to that of the aqueous pores in the SC. For this purpose, we have conducted in vitro mannitol skin permeability and average skin electrical resistivity measurements upon exposure of the skin to an aqueous SCI contacting solution in the context of a hindered-transport aqueous porous pathway model of the SC. These in vitro studies demonstrate that an SCI micelle of radius 33.5 +/- 1 Angstrom (as determined using dynamic light-scattering measurements) experiences significant steric hindrance and cannot penetrate into the SC through aqueous pores that have an average radius of 29 +/- 5 Angstrom. We believe that this inability of the SCI micelles to contribute to SCI skin penetration and associated skin barrier perturbation is responsible for the observed skin mildness of SCI. Through in vitro quantitative skin radioactivity assays using (14)C-radiolabeled SCI and pig full-thickness skin (p-FTS), we also show conclusively that SCI skin penetration is dose-independent, an important finding that provides additional evidence that the larger SCI micelles cannot penetrate into the SC through the smaller aqueous pores that exist in the SC, and therefore, cannot induce skin barrier perturbation.

The role of sodium dodecyl sulfate (SDS) micelles in inducing skin barrier perturbation in the presence of glycerol.

The stratum corneum (SC) serves as the skin barrier between the body and the environment. When the skin is contacted with an aqueous solution of the surfactant sodium dodecyl sulfate (SDS), a well-known model skin irritant, SDS penetrates into the skin and disrupts this barrier. It is well established, both in vitro and in vivo, that the SDS skin penetration is dose-dependent, and that it increases with an increase in the total SDS concentration above the critical micelle concentration (CMC) of SDS. However, when we added the humectant glycerol at a concentration of 10 wt% to the aqueous SDS contacting solution, we observed, through in vitro quantitative skin radioactivity assays using (14)C-radiolabeled SDS, that the dose dependence in SDS skin penetration is almost completely eliminated. To rationalize this important observation, which may also be related to the well-known beneficial effects of glycerol on skin barrier perturbation in vivo, we hypothesize that the addition of 10 wt% glycerol may hinder the ability of the SDS micelles to penetrate into the skin barrier through aqueous pores that exist in the SC. To test this hypothesis, we conducted mannitol skin permeability as well as average skin electrical resistivity measurements in vitro upon exposure of the skin to an aqueous SDS contacting solution and to an aqueous SDS + 10 wt% glycerol contacting solution in the context of a hindered-transport aqueous porous pathway model of the SC. Our in vitro studies demonstrated that the addition of 10 wt% glycerol: (i) reduces the average aqueous pore radius resulting from exposure of the skin to the aqueous SDS contacting solution from 33 +/- 5 Angstrom to 20 +/- 5 Angstrom, such that a SDS micelle of radius 18.5 +/- 1 Angstrom (as determined using dynamic light-scattering measurements) experiences significant steric hindrance and cannot penetrate into the SC, and (ii) reduces the number density of aqueous pores in the SC by more than 50%, thereby further reducing the ability of the SDS micelles to penetrate into the SC and perturb the skin barrier.

Ranking of aqueous surfactant-humectant systems based on an analysis of in vitro and in vivo skin barrier perturbation measurements.

We propose that skin electrical current measurements can be used in vitro to effectively rank aqueous solutions containing surfactants and humectants (the enhancer) contacting the skin, relative to a PBS aqueous solution (the control) contacting the skin, based on their ability to perturb the skin aqueous pores. Specifically, we develop an in vitro ranking metric using the increase in the skin electrical current induced by an enhancer relative to the control. Aqueous contacting solutions containing (i) surfactants [SDS (sodium dodecyl sulfate)] and C(12)E(6) [dodecyl hexa (ethylene oxide)], (ii) humectants (glycerol and propylene glycol), and (iii) a control (PBS) were studied. Utilizing the new in vitro ranking metric, these aqueous contacting solutions were ranked as follows (from the mildest to the harshest): glycerol < propylene glycol < PBS < C(12)E(6) < SDS. In order to further develop this ranking methodology, which can potentially lead to the reduction, or elimination, of costly and time-consuming procedures, such as human and animal testing and trial-and-error screening in vivo, it was important to correlate the findings of the in vitro ranking metric with direct in vivo skin barrier measurements. For this purpose, in vivo soap chamber measurements, including transepidermal water loss, visual skin dryness, and chromameter erythema measurements, were carried out on human volunteers using the aqueous surfactant-humectant solutions described above. The results of these in vivo measurements were found to be consistent with the ranking results obtained using the in vitro ranking metric. To further explore the validity of our model and to verify the skin barrier mitigating effect of glycerol, in vivo soap chamber measurements were carried out for aqueous SDS solutions containing 10 wt% added glycerol. These in vivo measurements support our recent in vitro finding that glycerol reduces the average radius and the pore number density of the skin aqueous pores, such that SDS micelles are hindered from penetrating into the skin and inducing skin barrier perturbation.