Assessment of Tilapia Skin Collagen for Biomedical Research Applications in Comparison with Mammalian Collagen.

Collagen is an important material for biomedical research, but using mammalian tissue-derived collagen carries the risk of zoonotic disease transmission. Marine organisms, such as farmed tilapia, have emerged as a safe alternative source of collagen for biomedical research. However, the tilapia collagen products for biomedical research are rare, and their biological functions remain largely unexamined. In this study, we characterized a commercial tilapia skin collagen using SDS-PAGE and fibril formation assays and evaluated its effects on skin fibroblast adhesion, proliferation, and migration, comparing it with commercial collagen from rat tails, porcine skin, and bovine skin. The results showed that tilapia skin collagen is a type I collagen, similar to rat tail collagen, and has a faster fibril formation rate and better-promoting effects on cell migration than porcine and bovine skin collagen. We also confirmed its application in a 3D culture for kidney cells' spherical cyst formation, fibroblast-induced gel contraction, and tumor spheroid interfacial invasion. Furthermore, we demonstrated that the freeze-dried tilapia skin collagen scaffold improved wound closure in a mouse excisional wound model, similar to commercial porcine or bovine collagen wound dressings. In conclusion, tilapia skin collagen is an ideal biomaterial for biomedical research.

Dichotomy of the function of DDR1 in cells and disease progression.

Discoidin domain receptors DDR1 and DDR2 are collagen receptor tyrosine kinases that have many roles in tissue development and disease progression. Under physiological conditions, DDR1 is predominantly expressed in epithelial cells and functions to maintain cell differentiation and tissue homeostasis. A switch in expression from DDR1 to DDR2 occurs during epithelial-to-mesenchymal transition. However, opposite effects of DDR1 are reported to be involved in the progression of cancer and fibrotic diseases. Accumulating evidence suggests that DDR1 is involved in pro-metastasis and pro-survival signals. This review summarizes the roles of DDR1 in epithelial cell differentiation, cell migration, cancer progression and tissues fibrosis and highlights how the dichotomous functions of DDR1 may relevant to different cell types and statues. Elucidation of the underlying mechanism of the dichotomous functions of DDR1 will help to develop DDR1 as a therapeutic target.

Bcl-2 regulates store-operated Ca2+ entry to modulate ER stress-induced apoptosis.

Ca2+ plays a significant role in linking the induction of apoptosis. The key anti-apoptotic protein, Bcl-2, has been reported to regulate the movement of Ca2+ across the ER membrane, but the exact effect of Bcl-2 on Ca2+ levels remains controversial. Store-operated Ca2+ entry (SOCE), a major mode of Ca2+ uptake in non-excitable cells, is activated by depletion of Ca2+ in the ER. Depletion of Ca2+ in the ER causes translocation of the SOC channel activator, STIM1, to the plasma membrane. Thereafter, STIM1 binds to Orai1 or/and TRPC1 channels, forcing them to open and thereby allow Ca2+ entry. In addition, several anti-cancer drugs have been reported to induce apoptosis of cancer cells via the SOCE pathway. However, the detailed mechanism underlying the regulation of SOCE by Bcl-2 is not well understood. In this study, a three-amino acid mutation within the Bcl-2 BH1 domain was generated to verify the role of Bcl-2 in Ca2+ handling during ER stress. The subcellular localization of the Bcl-2 mutant (mt) is similar to that in the wild-type Bcl-2 (WT) in the ER and mitochondria. We found that mt enhanced thapsigargin and tunicamycin-induced apoptosis through ER stress-mediated apoptosis but not through the death receptor- and mitochondria-dependent apoptosis, while WT prevented thapsigargin- and tunicamycin-induced apoptosis. In addition, mt depleted Ca2+ in the ER lumen and also increased the expression of SOCE-related molecules. Therefore, a massive Ca2+ influx via SOCE contributed to caspase activation and apoptosis. Furthermore, inhibiting SOCE or chelating either extracellular or intracellular Ca2+ inhibited mt-mediated apoptosis. In brief, our results explored the critical role of Bcl-2 in Ca2+ homeostasis and the modulation of ER stress.

Caveolin-1 down-regulation is required for Wnt5a-Frizzled 2 signalling in Ha-RasV12 -induced cell transformation.

Caveolin-1 (Cav1) is down-regulated during MK4 (MDCK cells harbouring inducible Ha-RasV12 gene) transformation by Ha-RasV12 . Cav1 overexpression abrogates the Ha-RasV12 -driven transformation of MK4 cells; however, the targeted down-regulation of Cav1 is not sufficient to mimic this transformation. Cav1-silenced cells, including MK4/shCav1 cells and MDCK/shCav1 cells, showed an increased cell area and discontinuous junction-related proteins staining. Cellular and mechanical transformations were completed when MDCK/shCav1 cells were treated with medium conditioned by MK4 cells treated with IPTG (MK4+I-CM) but not with medium conditioned by MK4 cells. Nanoparticle tracking analysis showed that Ha-RasV12 -inducing MK4 cells increased exosome-like microvesicles release compared with their normal counterparts. The cellular and mechanical transformation activities of MK4+I-CM were abolished after heat treatment and exosome depletion and were copied by exosomes derived from MK4+I-CM (MK4+I-EXs). Wnt5a, a downstream product of Ha-RasV12 , was markedly secreted by MK4+I-CM and MK4+I-EXs. Suppression of Wnt5a expression and secretion using the porcupine inhibitor C59 or Wnt5a siRNA inhibited the Ha-RasV12 - and MK4+I-CM-induced transformation of MK4 cells and MDCK/shCav1 cells, respectively. Cav1 down-regulation, either by Ha-RasV12 or targeted shRNA, increased frizzled-2 (Fzd2) protein levels without affecting its mRNA levels, suggesting a novel role of Cav1 in negatively regulating Fzd2 expression. Additionally, silencing Cav1 facilitated the internalization of MK4+I-EXs in MDCK cells. These data suggest that Cav1-dependent repression of Fzd2 and exosome uptake is potentially relevant to its antitransformation activity, which hinders the activation of Ha-RasV12 -Wnt5a-Stat3 pathway. Altogether, these results suggest that both decreasing Cav1 and increasing exosomal Wnt5a must be implemented during Ha-RasV12 -driven cell transformation.

Mechanical forces in skin disorders.

Mechanical forces are known to regulate homeostasis of the skin and play a role in the pathogenesis of skin diseases. The epidermis consists of keratinocytes that are tightly adhered to each other by cell junctions. Defects in keratins or desmosomal/hemidesmosomal proteins lead to the attenuation of mechanical strength and formation of intraepidermal blisters in the case of epidermolysis bullosa simplex. The dermis is rich in extracellular matrix, especially collagen, and provides the majority of tensile force in the skin. Keloid and hypertrophic scar, which is the result of over-production of collagen by fibroblasts during the wound healing, are associated with extrinsic tensile forces and changes of intrinsic mechanical properties of the cell. Increasing evidences shows that stiffness of the skin environment determines the regenerative ability during wound healing process. Mechanotransduction pathways are also involved in the morphogenesis and cyclic growth of hair follicles. The development of androgenetic alopecia is correlated to tensile forces generated by the fibrous tissue underlying the scalp. Acral melanoma predominantly occurs in the weight-bearing area of the foot suggesting the role of mechanical stress. Increased dermal stiffness from fibrosis might be the cause of recessive dystrophic epidermolysis bullosa associated squamous cell carcinoma. Strategies to change the mechanical forces or modify the mechanotransduction signals may lead to a new way to treat skin diseases and promote skin regeneration.

Caveolin-1 Controls Hyperresponsiveness to Mechanical Stimuli and Fibrogenesis-Associated RUNX2 Activation in Keloid Fibroblasts.

Keloids are pathological scars characterized by excessive extracellular matrix production that are prone to form in body sites with increased skin tension. CAV1, the principal coat protein of caveolae, has been associated with the regulation of cell mechanics, including cell softening and loss of stiffness sensing ability in NIH3T3 fibroblasts. Although CAV1 is present in low amounts in keloid fibroblasts (KFs), the causal association between CAV1 down-regulation and its aberrant responses to mechanical stimuli remain unclear. In this study, atomic force microscopy showed that KFs were softer than normal fibroblasts with a loss of stiffness sensing. The decrease of CAV1 contributed to the hyperactivation of fibrogenesis-associated RUNX2, a transcription factor germane to osteogenesis/chondrogenesis, and increased migratory ability in KFs. Treatment of KFs with trichostatin A, which increased the acetylation level of histone H3, increased CAV1 and decreased RUNX2 and fibronectin. Trichostatin A treatment also resulted in cell stiffening and decreased migratory ability in KFs. Collectively, these results suggest a role for CAV1 down-regulation in linking the aberrant responsiveness to mechanical stimulation and extracellular matrix accumulation with the progression of keloids, findings that may lead to new developments in the prevention and treatment of keloid scarring.

Overexpression of exogenous kidney-specific Ngal attenuates progressive cyst development and prolongs lifespan in a murine model of polycystic kidney disease.

Neutrophil gelatinase-associated lipocalin (Ngal) is a biomarker for acute and chronic renal injuries, including polycystic kidney disease (PKD). However, the effect of Ngal on PKD progression remains unexplored. To study this, we generated 3 strains of mice with different expression levels of Ngal within an established PKD model (Pkd1L3/L3): Pkd1L3/L3 (with endogenous Ngal), Pkd1L3/L3; NgalTg/Tg (with endogenous and overexpression of exogenous kidney-specific Ngal) and Pkd1L3/L3; Ngal-/- mice (with Ngal deficiency). Knockout of endogenous Ngal had no effect on phenotypes, cystic progression, or survival of the PKD mice. However, the transgenic mice had a significantly longer lifespan, smaller (but not fewer) renal cysts, and less interstitial fibrosis than the mice without or with endogenous Ngal. Western-blot analyses showed significant increases in Ngal and cleaved caspase-3 and decreases in α-smooth muscle actin, hypoxia-inducible factor 1-α, pro-caspase 3, proliferating cell nuclear antigen, Akt, mammalian target of rapamycin, and S6 Kinase in the transgenic mice as compared with the other 2 strains of PKD mice. Thus, overexpression of exogenous kidney-specific Ngal reduced cystic progression and prolonged the lifespan in PKD mice, was associated with reductions in interstitial fibrosis and proliferation, and augmented apoptosis.

Spatial distribution of filament elasticity determines the migratory behaviors of a cell.

Any cellular response leading to morphological changes is highly tuned to balance the force generated from structural reorganization, provided by actin cytoskeleton. Actin filaments serve as the backbone of intracellular force, and transduce external mechanical signal via focal adhesion complex into the cell. During migration, cells not only undergo molecular changes but also rapid mechanical modulation. Here we focus on determining, the role of spatial distribution of mechanical changes of actin filaments in epithelial, mesenchymal, fibrotic and cancer cells with non-migration, directional migration, and non-directional migration behaviors using the atomic force microscopy. We found 1) non-migratory cells only generated one type of filament elasticity, 2) cells generating spatially distributed two types of filament elasticity showed directional migration, and 3) pathologic cells that autonomously generated two types of filament elasticity without spatial distribution were actively migrating non-directionally. The demonstration of spatial regulation of filament elasticity of different cell types at the nano-scale highlights the coupling of cytoskeletal function with physical characters at the sub-cellular level, and provides new research directions for migration related disease.

Mechanical phenotype of cancer cells: cell softening and loss of stiffness sensing.

The stiffness sensing ability is required to respond to the stiffness of the matrix. Here we determined whether normal cells and cancer cells display distinct mechanical phenotypes. Cancer cells were softer than their normal counterparts, regardless of the type of cancer (breast, bladder, cervix, pancreas, or Ha-RasV12-transformed cells). When cultured on matrices of varying stiffness, low stiffness decreased proliferation in normal cells, while cancer cells and transformed cells lost this response. Thus, cancer cells undergo a change in their mechanical phenotype that includes cell softening and loss of stiffness sensing. Caveolin-1, which is suppressed in many tumor cells and in oncogene-transformed cells, regulates the mechanical phenotype. Caveolin-1-upregulated RhoA activity and Y397FAK phosphorylation directed actin cap formation, which was positively correlated with cell elasticity and stiffness sensing in fibroblasts. Ha-RasV12-induced transformation and changes in the mechanical phenotypes were reversed by re-expression of caveolin-1 and mimicked by the suppression of caveolin-1 in normal fibroblasts. This is the first study to describe this novel role for caveolin-1, linking mechanical phenotype to cell transformation. Furthermore, mechanical characteristics may serve as biomarkers for cell transformation.

Vimentin contributes to epithelial-mesenchymal transition cancer cell mechanics by mediating cytoskeletal organization and focal adhesion maturation.

Modulations of cytoskeletal organization and focal adhesion turnover correlate to tumorigenesis and epithelial-mesenchymal transition (EMT), the latter process accompanied by the loss of epithelial markers and the gain of mesenchymal markers (e.g., vimentin). Clinical microarray results demonstrated that increased levels of vimentin mRNA after chemotherapy correlated to a poor prognosis of breast cancer patients. We hypothesized that vimentin mediated the reorganization of cytoskeletons to maintain the mechanical integrity in EMT cancer cells. By using knockdown strategy, the results showed reduced cell proliferation, impaired wound healing, loss of directional migration, and increased large membrane extension in MDA-MB 231 cells. Vimentin depletion also induced reorganization of cytoskeletons and reduced focal adhesions, which resulted in impaired mechanical strength because of reduced cell stiffness and contractile force. In addition, overexpressing vimentin in MCF7 cells increased cell stiffness, elevated cell motility and directional migration, reoriented microtubule polarity, and increased EMT phenotypes due to the increased ß1-integrin and the loss of junction protein E-cadherin. The EMT-related transcription factor slug was also mediated by vimentin. The current study demonstrated that vimentin serves as a regulator to maintain intracellular mechanical homeostasis by mediating cytoskeleton architecture and the balance of cell force generation in EMT cancer cells.

Mechanosensitive store-operated calcium entry regulates the formation of cell polarity.

Ca(2+) -mediated formation of cell polarity is essential for directional migration which plays an important role in physiological and pathological processes in organisms. To examine the critical role of store-operated Ca(2+) entry, which is the major form of extracellular Ca(2+) influx in non-excitable cells, in the formation of cell polarity, we employed human bone osteosarcoma U2OS cells, which exhibit distinct morphological polarity during directional migration. Our analyses showed that Ca(2+) was concentrated at the rear end of cells and that extracellular Ca(2+) influx was important for cell polarization. Inhibition of store-operated Ca(2+) entry using specific inhibitors disrupted the formation of cell polarity in a dose-dependent manner. Moreover, the channelosomal components caveolin-1, TRPC1, and Orai1 were concentrated at the rear end of polarized cells. Knockdown of TRPC1 or a TRPC inhibitor, but not knockdown of Orai1, reduced cell polarization. Furthermore, disruption of lipid rafts or overexpression of caveolin-1 contributed to the downregulation of cell polarity. On the other hand, we also found that cell polarity, store-operated Ca(2+) entry activity, and cell stiffness were markedly decreased by low substrate rigidity, which may be caused by the disorganization of actin filaments and microtubules that occurs while regulating the activity of the mechanosensitive TRPC1 channel.

A tale of two collagen receptors, integrin ß1 and discoidin domain receptor 1, in epithelial cell differentiation.

As increase in collagen deposition is no longer taken as simply a consequence but, rather, an inducer of disease progression; therefore, the understanding of collagen signal transduction is fundamentally important. Cells contain at least two types of collagen receptors: integrins and discoidin domain receptors (DDRs). The integrin heterodimers α(1)ß(1), α(2)ß(1), α(10)ß(1), and α(11)ß(1) are recognized as the non-tyrosine kinase collagen receptors. DDR1 and 2, the tyrosine kinase receptors of collagen, are specifically expressed in epithelium and mesenchyme, respectively. While integrin ß(1) and DDR1 are both required for cell adhesion on collagen, their roles in epithelial cell differentiation during development and disease progression seem to counteract each other, with integrin ß(1) favoring epithelium mesenchyme transition (EMT) and DDR1 inducing epithelial cell differentiation. The in vitro evidence shows that the integrin ß(1) and DDR1 exert opposing actions in regulation of membrane stability of E-cadherin, which itself is a critical regulator of epithelial cell differentiation. Here, we review the functional roles of integrin ß(1) and DDR1 in regulation of epithelial cell differentiation during development and disease progression, and explore the underlining mechanisms regarding to the regulation of membrane stability of E-cadherin.

Cigarette dependence questionnaire: development and psychometric testing with male smokers.

AIM: This paper is a report of a study conducted to develop and test a theoretically derived Cigarette Dependence Questionnaire for adult male smokers. BACKGROUND: Fagerstrom questionnaires have been used worldwide to assess cigarette dependence. However, these assessments lack any theoretical perspective. A theory-based approach is needed to ensure valid assessment. METHODS: In 2007, an initial pool of 103 Cigarette Dependence Questionnaire items was distributed to 109 adult smokers in Taiwan. Item analysis was conducted to select items for inclusion in the refined scale. The psychometric properties of the Cigarette Dependence Questionnaire were further evaluated 2007-08, when it was administered to 256 respondents and their saliva was collected and analysed for cotinine levels. Criterion validity was established through the Pearson correlation between the scale and saliva cotinine levels. Exploratory factor analysis was used to test construct validity. Reliability was determined with Cronbach's alpha coefficient and a 2-week test-retest coefficient. RESULTS: The selection of 30 items for seven perspectives was based on item analysis. One factor accounting for 44.9% of the variance emerged from the factor analysis. The factor was named as cigarette dependence. Cigarette Dependence Questionnaire scores were statistically significantly correlated with saliva cotinine levels (r = 0.21, P = 0.01). Cronbach's alpha was 0.95 and test-retest reliability using an intra-class correlation was 0.92. CONCLUSION: The Cigarette Dependence Questionnaire showed sound reliability and validity and could be used by nurses to set up smoking cessation interventions based on assessment of cigarette dependence.

Mouse kidney progenitor cells accelerate renal regeneration and prolong survival after ischemic injury.

Acute tubular necrosis is followed by regeneration of damaged renal tubular epithelial cells, and renal stem cells are supposed to contribute to this process. The purpose of our study is to test the hypothesis that renal stem cells isolated from adult mouse kidney accelerate renal regeneration via participation in the repair process. A unique population of cells exhibiting characteristics consistent with renal stem cells, mouse kidney progenitor cells (MKPC), was isolated from Myh9 targeted mutant mice. Features of these cells include (1) spindle-shaped morphology, (2) self-renewal of more than 100 passages without evidence of senescence, and (3) expression of Oct-4, Pax-2, Wnt-4, WT-1, vimentin, alpha-smooth muscle actin, CD29, and S100A4 but no SSEA-1, c-kit, or other markers of more differentiated cells. MKPC exhibit plasticity as demonstrated by the ability to differentiate into endothelial cells and osteoblasts in vitro and endothelial cells and tubular epithelial cells in vivo. The origin of the isolated MKPC was from the interstitium of medulla and papilla. Importantly, intrarenal injection of MKPC in mice with ischemic injury rescued renal damage, as manifested by decreases in peak serum urea nitrogen, the infarct zone, and the necrotic injury. Seven days after the injury, some MKPC formed vessels with red blood cells inside and some incorporated into renal tubules. In addition, MKPC treatment reduces the mortality in mice after ischemic injury. Our results indicate that MKPC represent a multipotent adult stem cell population, which may contribute to the renal repair and prolong survival after ischemic injury.

Psychometric testing of the Chinese version of the Hooked on Nicotine Checklist in adolescents.

PURPOSE: To examine the psychometric properties of the Hooked on Nicotine Checklist (HONC) on a Taiwanese sample. The HONC as a measure of nicotine dependence in adolescents is in worldwide use. Less is known regarding its psychometric properties for a Chinese population. METHODS: A cross-sectional, descriptive study was conducted from January to May 2008 with 373 male adolescent smokers aged 15 to 20 years. The criterion validity of the Chinese HONC was determined using the Fagerstrom Test of Nicotine Dependence (FTND) and saliva cotinine. Because the responses to the items are dichotomous, the validity and factorial structures were examined using tetrachoric and biserial techniques by PRELIS 2 and LISREL 8.7. RESULTS: Most of interitem correlations are between 0.3 and 0.7. Each item is highly associated with the full scale (r > .7). The HONC total score is significantly associated with the FTND (r=.58, p < .01) and with saliva cotinine levels (r=.27, p < .05). Confirmatory factor analyses were performed to compare the relative fit of three competing models. The three-correlated factor model has a better fit than other models, according to the cutoff criteria for relatively good fit. The coefficient alpha of the full scale is .83. CONCLUSIONS: The Chinese version of the HONC is a reliable and valid measure of tobacco dependence in adolescent smokers. Studies involving female adolescent and younger smokers will be needed to evaluate the applicability of the scales to the different genders and age populations.

Psychometric testing of the Chinese version of the Dimensions of Tobacco Dependence Scale.

AIMS: This paper reports on a study to establish the psychometric properties of the Chinese version of the dimensions of Tobacco Dependence Scale as these apply in Taiwan. BACKGROUND: The instruments for measuring cigarette dependence among adolescent smokers are not available in Taiwan. Therefore, it has not so far been possible to assess such dependence. DESIGN: Survey. METHOD: A sample comprising 293 adolescent smokers was recruited. They were drawn from nine senior high schools in middle and southern Taiwan. The Dimensions of Tobacco Dependence Scale and the Fagerstrom Test of nicotine dependence were administered, with saliva being subjected to salivary cotinine analysis using competitive enzyme immunoassay kits. RESULTS: The internal structure of the Dimensions of Tobacco Dependence Scale (DTDS) was first examined using exploratory factor analysis with promax rotation. By applying the parallel test as the means of selection, four criteria emerged from the factor analysis that accounted for 47.7% of the variance. Concerning criterion validity, the DTDS was found to have a positive and significant association with the Fagerstrom test of nicotine dependence scores (r = 0.58; p < 0.01) and with saliva cotinine levels (r = 0.30; p < 0.01). Cronbach's alpha values for the DTDS were 0.94. CONCLUSIONS: The study confirmed that the Chinese version of the DTDS is similar to the English version in that it is multidimensional and has consistent factor structures. And, as a result of the study, it was established that the Chinese version of the Dimensions of Tobacco Dependence Scale is a reliable and valid measure of tobacco dependence among adolescents in Taiwan. RELEVANCE TO CLINICAL PRACTICE: The DTDS can provide health professionals with a reference measure for assessing adolescents' tobacco dependence when applied in the context of a smoking cessation programme.

Mechanosensing machinery for cells under low substratum rigidity.

Mechanical stimuli are essential during development and tumorigenesis. However, how cells sense their physical environment under low rigidity is still unknown. Here we show that low rigidity of collagen gel downregulates beta(1)-integrin activation, clustering, and focal adhesion kinase (FAK) Y397 phosphorylation, which is mediated by delayed raft formation. Moreover, overexpression of autoclustered beta(1)-integrin (V737N), but not constitutively active beta(1)-integrin (G429N), rescues FAKY397 phosphorylation level suppressed by low substratum rigidity. Using fluorescence resonance energy transfer to assess beta(1)-integrin clustering, we have found that substratum rigidity between 58 and 386 Pa triggers beta(1)-integrin clustering in a dose-dependent manner, which is highly dependent on actin filaments but not microtubules. Furthermore, augmentation of beta(1)-integrin clustering enhances the interaction between beta(1)-integrin, FAK, and talin. Our results indicate that contact with collagen fibrils is not sufficient for integrin activation. However, substratum rigidity is required for integrin clustering and activation. Together, our findings provide new insight into the mechanosensing machinery and the mode of action for epithelial cells in response to their physical environment under low rigidity.

Smoking characteristics and saliva cotinine levels in Taiwanese smokers: gender differences.

AIMS: The present study examined the smoking characteristics and a biomarker of a community-based sample of Taiwanese individuals, seeking to determine the correlates of nicotine dependence for each gender. BACKGROUND: Nicotine dependence is a key barrier to smoking cessation. Additionally, nicotine metabolism may influence smoking behaviour and dependence. Correlates of nicotine dependence and biochemical markers of smoking for the Taiwanese population have not yet been studied. METHODS: Participants were 402 men and 110 women smokers, who had recently smoked at least one cigarette every day over a recent year. All participants completed a questionnaire which included demographic data, smoking background, self-reported quantity of cigarettes per day and the Fagerstrom Test for Nicotine Dependence. The participants also provided saliva samples. RESULTS: Female smokers were younger, more likely to be unmarried and were on average higher educated than males. A higher percentage of females reported that family members smoked and tended to be younger at initiation and were also more likely to have attempted to quit on previous occasions. Males reported smoking significantly more cigarettes than females, however, there was no significant difference in the Fagerstrom Test for Nicotine Dependence scores between the two groups. The average saliva cotinine level was significantly higher for males than females (228.8 ng/ml vs. 94.6 ng/ml, p < 0.0001). Family and friends smoking were risk factors of nicotine dependence among both men and women smokers, but there was a stronger association of both factors on dependence levels for women. Being married is a risk factor for dependence for women but not for men. CONCLUSION: These findings support the evidence that smoking characteristics and a biochemical marker differ between the males and females. RELEVANCE TO CLINICAL PRACTICE: The results of the study are useful for health policymakers, assisting them in planning tobacco control activities in light of gender differences.

Evaluating screening performances of the Fagerstrom tolerance questionnaire, the Fagerstrom test for nicotine dependence and the heavy smoking index among Taiwanese male smokers.

AIM: To compare screening performances of the Fagerstrom Tolerance Questionnaire (FTQ), the Fagerstrom test for nicotine dependence (FTND) and the Heavy Smoking Index (HSI) with a view to determining the optimum cutoff scores using biomarkers as standards. BACKGROUND: Previous studies proposed inconsistent cutoff scores for the FTQ, the FTND as signalling nicotine dependence and these scores were established by applying diverse standards. METHOD: Receiver operating characteristic (ROC) analyses were used in pursuit of the study's objectives. Two hundred and forty-five male smokers were recruited in 2005 from among those attending public health stations in southern Taiwan. The three self-report measures of nicotine dependence were compared with the saliva cotinine and expired carbon monoxide (CO). The expired CO level was tested by means of a Micro Smokerlyzer, while salivary cotinine was analysed using an enzyme-linked immunosorbent assay. RESULTS: The areas under the ROC curves for the FTQ, the FTND and the HSI were 0.71, 0.76 and 0.76 for the salivary cotinine and 0.71, 0.79 and 0.80 for the exhaled CO respectively. The sensitivity and specificity of the FTND and the HSI were slightly greater than those for the FTQ. The optimum cutoff scores for the FTQ, the FTND and the HSI as screening tools to establish nicotine dependence would be 5+, 4+ and 3+ respectively. CONCLUSION: The results indicate that the FTND and the HSI may be more efficacious than the FTQ in assessing nicotine dependence. Further research is needed to confirm these findings, especially among female smokers and for nicotine substitution trials. Relevance to clinical practice. To decrease tobacco-attributable morbidity and mortality, nurses and healthcare professionals need to implement effective smoking cessation interventions. The FTND and the HSI as well as their cutoff scores will be suitably used to assess nicotine dependence in these interventions.