Dynamically Mapping the Topography and Stiffness of the Leading Edge of Migrating Cells Using AFM in Fast-QI Mode

Cell migration profoundly influences cellular function, often resulting in adverse effects in various pathologies including cancer metastasis. Directly assessing and quantifying the nanoscale dynamics of living cell structure and mechanics has remained a challenge. At the forefront of cell movement, the flat actin modules─the lamellipodium and the lamellum─interact to propel cell migration. The lamellipodium extends from the lamellum and undergoes rapid changes within seconds, making measurement of its stiffness a persistent hurdle. In this study, we introduce the fast-quantitative imaging (fast-QI) mode, demonstrating its capability to simultaneously map both the lamellipodium and the lamellum with enhanced spatiotemporal resolution compared with the classic quantitative imaging (QI) mode. Specifically, our findings reveal nanoscale stiffness gradients in the lamellipodium at the leading edge, where it appears to be slightly thinner and significantly softer than the lamellum. Additionally, we illustrate the fast-QI mode's accuracy in generating maps of height and effective stiffness through a streamlined and efficient processing of force-distance curves. These results underscore the potential of the fast-QI mode for investigating the role of motile cell structures in mechanosensing.

Mechanical Characterization of Murine Oocytes by Atomic Force Microscopy

The quality of murine and human oocytes correlates to their mechanical properties, which are tightly regulated to reach the blastocyst stage after fertilization. Oocytes are nonadherent spherical cells with a diameter over 80 μm. Their mechanical properties have been studied in our lab and others using the micropipette aspiration technique, particularly to obtain the oocyte cortical tension. Micropipette aspiration is affordable but has a low throughput and induces cell-scale deformation. Here we present a step-by-step protocol to characterize the mechanical properties of oocytes using atomic force microscopy (AFM), which is minimally invasive and has a much higher throughput. We used electron microscopy grids to immobilize oocytes. This allowed us to obtain local and reproducible measurements of the cortical tension of murine oocytes during their meiotic divisions. Cortical tension values obtained by AFM are in agreement with the ones previously obtained by micropipette aspiration. Our protocol could help characterize the biophysical properties of oocytes or other types of large nonadherent samples in fundamental and medical research.

Spatial Control of Arp2/3-Induced Actin Polymerization on Phase-Separated Giant Unilamellar Vesicles

Deciphering the physical mechanisms underlying cell shape changes, while avoiding the cellular interior's complexity, involves the development of controlled basic biomimetic systems that imitate cell functions. In particular, the reconstruction of cytoskeletal dynamics on cell-sized giant unilamellar vesicles (GUVs) has allowed for the reconstituting of some cell-like processes in vitro. In fact, such a bottom-up strategy could be the basis for forming protocells able to reorganize or even move autonomously. However, reconstituting the subtle and controlled dynamics of the cytoskeleton-membrane interface in vitro remains an experimental challenge. Taking advantage of the lipid-induced segregation of an actin polymerization activator, we present a system that targets actin polymerization in specific domains of phase-separated GUVs. We observe actin networks localized on Lo, Ld, or on both types of domains and the actin-induced deformation or reorganization of these domains. These results suggest that the system we have developed here could pave the way for future experiments further detailing the interplay between actin dynamics and membrane heterogeneities.

Using Adhesive Micropatterns and AFM to Assess Cancer Cell Morphology and Mechanics

The mechanical properties of living cells reflect their physiological and pathological state. In particular, cancer cells undergo cytoskeletal modifications that typically make them softer than healthy cells, a property that could be used as a diagnostic tool. However, this is challenging because cells are complex structures displaying a broad range of morphologies when cultured in standard 2D culture dishes. Here, we use adhesive micropatterns to impose the cell geometry and thus standardize the mechanics and morphologies of cancer cells, which we measure by atomic force microscopy (AFM), mechanical nanomapping, and membrane nanotube pulling. We show that micropatterning cancer cells leads to distinct morphological and mechanical changes for different cell lines. Micropatterns did not systematically lower the variability in cell elastic modulus distribution. These effects emerge from a variable cell spreading rate associated with differences in the organization of the cytoskeleton, thus providing detailed insights into the structure-mechanics relationship of cancer cells cultured on micropatterns. Combining AFM with micropatterns reveals new mechanical and morphological observables applicable to cancer cells and possibly other cell types.

Studying actin-induced cell shape changes using Giant Unilamellar Vesicles and reconstituted actin networks

Cell shape changes that are fuelled by the dynamics of the actomyosin cytoskeleton control cellular processes such as motility and division. However, the mechanisms of interplay between cell membranes and actomyosin are complicated to decipher in the complex environment of the cytoplasm. Using biomimetic systems offers an alternative approach to studying cell shape changes in assays with controlled biochemical composition. Biomimetic systems allow quantitative experiments that can help to build physical models describing the processes of cell shape changes. This article reviews works in which actin networks are reconstructed inside or outside cell-sized Giant Unilamellar Vesicles (GUVs), which are models of cell membranes. We show how various actin networks affect the shape and mechanics of GUVs and how some cell shape changes can be reproduced in vitro using these minimal systems.

Methods for Assessing Oocyte Quality: A Review of Literature

The rate of infertility continues to rise in the world for several reasons, including the age of conception and current lifestyle. We list in this paper potential non-invasive and invasive techniques to assess oocyte quality. We searched the database PubMed using the terms “oocytes AND quality AND evaluation”. In the first part, we study the morphological criteria, compartment by compartment, to then focus in a second part on more objective techniques such as genetics, molecular, apoptosis, or human follicular fluid that contain biologically active molecules. The main criteria used to assess oocyte quality are morphological; however, several other techniques have been studied in women to improve oocyte quality assessment, but most of them are invasive and not usable in routine.

Remodelling of membrane tubules by the actin cytoskeleton

Inside living cells, the remodelling of membrane tubules by actomyosin networks is crucial for processes such as intracellular trafficking or organelle reshaping. In this review, we first present various in vivo situations in which actin affects membrane tubule remodelling, then we recall some results on force production by actin dynamics and on membrane tubules physics. Finally, we show that our knowledge of the underlying mechanisms by which actomyosin dynamics affect tubule morphology has recently been moved forward. This is thanks to in vitro experiments that mimic cellular membranes and actin dynamics and allow deciphering the physics of tubule remodelling in biochemically controlled conditions, and shed new light on tubule shape regulation.

Fluctuations of a membrane nanotube covered with an actin sleeve

Many biological functions rely on the reshaping of cell membranes, in particular into nanotubes, which are covered in vivo by dynamic actin networks. Nanotubes are subject to thermal fluctuations, but the effect of these on cell functions is unknown. Here, we form nanotubes from liposomes using an optically trapped bead adhering to the liposome membrane. From the power spectral density of this bead, we study the nanotube fluctuations in the range of membrane tensions measured in vivo. We show that an actin sleeve covering the nanotube damps its high-frequency fluctuations because of the network viscoelasticity. Our work paves the way for further studies of the effect of nanotube fluctuations on cellular functions.

Finger-like membrane protrusions are favored by heterogeneities in the actin network

Finger-like protrusions in cells are mostly generated by an active actin cytoskeleton pushing against the cell membrane. Conventional filopodia, localized at the leading edge of the cells, are long and thin protrusions composed of parallel actin filaments that emanate from a branched actin network. In contrast, dendritic filopodia, precursors of dendritic spines in neurons, are entirely filled in with a branched actin network. Here, we investigate in vitro how the dynamics of branched actin structures, polymerized at a membrane surface, trigger the formation of both protrusion types. Using supported bilayers and liposomes, we show that a decrease in the amount of activation sites at the membrane surface leads to the appearance of heterogeneities in the actin network coverage. Such heterogeneities promote the formation of membrane protrusions, and the size of heterogeneity patches matches the one of the protrusion base. Protrusion shape, cylindrical or conical, directly correlates with the absence or the presence of actin branches, respectively.

Actin modulates shape and mechanics of tubular membranes

The actin cytoskeleton shapes cells and also organizes internal membranous compartments. In particular, it interacts with membranes for intracellular transport of material in mammalian cells, yeast, or plant cells. Tubular membrane intermediates, pulled along microtubule tracks, are formed during this process and destabilize into vesicles. While the role of actin in tubule destabilization through scission is suggested, literature also provides examples of actin-mediated stabilization of membranous structures. To directly address this apparent contradiction, we mimic the geometry of tubular intermediates with preformed membrane tubes. The growth of an actin sleeve at the tube surface is monitored spatiotemporally. Depending on network cohesiveness, actin is able to entirely stabilize or locally maintain membrane tubes under pulling. On a single tube, thicker portions correlate with the presence of actin. These structures relax over several minutes and may provide enough time and curvature geometries for other proteins to act on tube stability.

Fluctuations of a membrane nanotube revealed by high-resolution force measurements

Pulling membrane nanotubes from liposomes presents a powerful method to gain access to membrane mechanics. Here we extend classical optical tweezers studies to infer membrane nanotube dynamics with high spatial and temporal resolution. We first validate our force measurement setup by accurately measuring the bending modulus of EPC membrane in tube pulling experiments. Then we record the position signal of a trapped bead when it is connected, or not, to a tube. We derive the fluctuation spectrum of these signals and find that the presence of a membrane nanotube induces higher fluctuations, especially at low frequencies (10-1000 Hz). We analyse these spectra by taking into account the peristaltic modes of nanotube fluctuations. This analysis provides a new experimental framework for a quantitative study of the fluctuations of nanotubular membrane structures that are present in living cells, and now classically used for in vitro biomimetic approaches.

Elasticity, Adhesion, and Tether Extrusion on Breast Cancer Cells Provide a Signature of Their Invasive Potential

We use single-cell force spectroscopy to compare elasticity, adhesion, and tether extrusion on four breast cancer cell lines with an increasing invasive potential. We perform cell attachment/detachment experiments either on fibronectin or on another cell using an atomic force microscope. Our study on the membrane tether formation from cancer cells show that they are easier to extrude from aggressive invasive cells. Measured elastic modulus values confirm that more invasive cells are softer. Moreover, the adhesion force increases with the invasive potential. Our results provide a mechanical signature of breast cancer cells that correlates with their invasivity.

How cellular membrane properties are affected by the actin cytoskeleton

Lipid membranes define the boundaries of living cells and intracellular compartments. The dynamic remodelling of these membranes by the cytoskeleton, a very dynamic structure made of active biopolymers, is crucial in many biological processes such as motility or division. In this review, we present some aspects of cellular membranes and how they are affected by the presence of the actin cytoskeleton. We show that, in parallel with the direct study of membranes and cytoskeleton in vivo, biomimetic in vitro systems allow reconstitution of biological processes in a controlled environment. In particular, we show that liposomes, or giant unilamellar vesicles, encapsulating a reconstituted actin network polymerizing at their membrane are suitable models of living cells and can be used to decipher the relative contributions of membrane and actin on the mechanical properties of the cellular interface.

Cell-sized liposome doublets reveal active tension build-up driven by acto-myosin dynamics

Cells modulate their shape to fulfill specific functions, mediated by the cell cortex, a thin actin shell bound to the plasma membrane. Myosin motor activity, together with actin dynamics, contributes to cortical tension. Here, we examine the individual contributions of actin polymerization and myosin activity to tension increase with a non-invasive method. Cell-sized liposome doublets are covered with either a stabilized actin cortex of preformed actin filaments, or a dynamic branched actin network polymerizing at the membrane. The addition of myosin II minifilaments in both cases triggers a change in doublet shape that is unambiguously related to a tension increase. Preformed actin filaments allow us to evaluate the effect of myosin alone while, with dynamic actin cortices, we examine the synergy of actin polymerization and myosin motors in driving shape changes. Our assay paves the way for a quantification of tension changes triggered by various actin-associated proteins in a cell-sized system.

F-actin mechanics control spindle centring in the mouse zygote

Mitotic spindle position relies on interactions between astral microtubules nucleated by centrosomes and a rigid cortex. Some cells, such as mouse oocytes, do not possess centrosomes and astral microtubules. These cells rely only on actin and on a soft cortex to position their spindle off-centre and undergo asymmetric divisions. While the first mouse embryonic division also occurs in the absence of centrosomes, it is symmetric and not much is known on how the spindle is positioned at the exact cell centre. Using interdisciplinary approaches, we demonstrate that zygotic spindle positioning follows a three-step process: (1) coarse centring of pronuclei relying on the dynamics of an F-actin/Myosin-Vb meshwork; (2) fine centring of the metaphase plate depending on a high cortical tension; (3) passive maintenance at the cell centre. Altogether, we show that F-actin-dependent mechanics operate the switch between asymmetric to symmetric division required at the oocyte to embryo transition.

Unexpected membrane dynamics unveiled by membrane nanotube extrusion

In cell mechanics, distinguishing the respective roles of the plasma membrane and of the cytoskeleton is a challenge. The difference in the behavior of cellular and pure lipid membranes is usually attributed to the presence of the cytoskeleton as explored by membrane nanotube extrusion. Here we revisit this prevalent picture by unveiling unexpected force responses of plasma membrane spheres devoid of cytoskeleton and synthetic liposomes. We show that a tiny variation in the content of synthetic membranes does not affect their static mechanical properties, but is enough to reproduce the dynamic behavior of their cellular counterparts. This effect is attributed to an amplified intramembrane friction. Reconstituted actin cortices inside liposomes induce an additional, but not dominant, contribution to the effective membrane friction. Our work underlines the necessity of a careful consideration of the role of membrane proteins on cell membrane rheology in addition to the role of the cytoskeleton.

Membrane tension regulates motility by controlling lamellipodium organization

Many cell movements proceed via a crawling mechanism, where polymerization of the cytoskeletal protein actin pushes out the leading edge membrane. In this model, membrane tension has been seen as an impediment to filament growth and cell motility. Here we use a simple model of cell motility, the Caenorhabditis elegans sperm cell, to test how membrane tension affects movement and cytoskeleton dynamics. To enable these analyses, we create transgenic worm strains carrying sperm with a fluorescently labeled cytoskeleton. Via osmotic shock and deoxycholate treatments, we relax or tense the cell membrane and quantify apparent membrane tension changes by the membrane tether technique. Surprisingly, we find that membrane tension reduction is correlated with a decrease in cell displacement speed, whereas an increase in membrane tension enhances motility. We further demonstrate that apparent polymerization rates follow the same trends. We observe that membrane tension reduction leads to an unorganized, rough lamellipodium, composed of short filaments angled away from the direction of movement. On the other hand, an increase in tension reduces lateral membrane protrusions in the lamellipodium, and filaments are longer and more oriented toward the direction of movement. Overall we propose that membrane tension optimizes motility by streamlining polymerization in the direction of movement, thus adding a layer of complexity to our current understanding of how membrane tension enters into the motility equation.

Influence of nomenclature in the interpretation of lumbar disk contour on MR imaging: a comparison of the agreement using the combined task force and the nordic nomenclatures

BACKGROUND AND PURPOSE

The CTF nomenclature had not been tested in clinical practice. The purpose of this study was to compare the reliability and diagnostic confidence in the interpretation of disk contours on lumbar 1.5T MR imaging when using the CTF and the Nordic nomenclatures.

MATERIALS AND METHODS

Five general radiologists from 3 hospitals blindly and independently assessed intravertebral herniations (Schmorl node) and disk contours on the lumbar MR imaging of 53 patients with low back pain, on 4 occasions. Measures were taken to minimize the risk of recall bias. The Nordic nomenclature was used for the first 2 assessments, and the CTF nomenclature, in the remaining 2. Radiologists had not previously used either of the 2 nomenclatures. κ statistics were calculated separately for reports deriving from each nomenclature and were categorized as almost perfect (0.81-1.00), substantial (0.61-0.80), moderate (0.41-0.60), fair (0.21-0.40), slight (0.00-0.20), and poor (<0.00).

RESULTS

Categorization of intra- and interobserver agreement was the same across nomenclatures. Intraobserver reliability was substantial for intravertebral herniations and disk contour abnormalities. Interobserver reliability was moderate for intravertebral herniations and fair to moderate for disk contour.

CONCLUSIONS

In conditions close to clinical practice, regardless of the specific nomenclature used, a standardized nomenclature supports only moderate interobserver agreement. The Nordic nomenclature increases self-confidence in an individual observer's report but is less clear regarding the classification of disks as normal versus bulged.

Respiratory tract infections after cardiac surgery: impact on hospital morbidity and mortality

AIM

Nosocomial pneumonia (NP) and tracheobronchitis after cardiac surgery are associated with worse outcomes. The aim of this study was to identify risk factors associated with NP and tracheobronchitis after cardiac surgery and to determine the impact of these infections on hospital morbidity and mortality.

METHODS

We evaluated 1600 adult patients undergoing cardiac surgery under standard cardiopulmonary bypass. Data were collected prospectively. All NP and tracheobronchitis episodes were confirmed by a semiquantitative culture of endotracheal aspirate. Logistic regression analysis was done to identify risk factors for respiratory tract infection and mortality.

RESULTS

The rate of NP was 1.2% (15.6 episodes per 1000 days of mechanical ventilation) and that of tracheobronchitis was 1.6% (21 episodes per 1000 days of mechanical ventilation). Significant independent risk factors for respiratory tract infection (pneumonia or tracheobronchitis) were: left ventricular ejection fraction < 30% (P = 0.001), chronic renal failure (P < 0.0001) and urgent surgery (P < 0.0001). Patients with NP had significantly higher mortality (42% versus 0.9%, P < 0.0001) than patients without respiratory tract infection. The median hospital length of stay was significantly longer in patients with pneumonia (42 days) and tracheobronchitis (28 days) than in patients without any respiratory tract infection (11 days, P < 0.0001).

CONCLUSION

NP after cardiac surgery is associated with severe outcomes. Independent risk markers for respiratory tract infection were left ventricular ejection fraction < 30%, chronic renal failure and urgent surgery.

Agreement in the interpretation of magnetic resonance images of the lumbar spine

BACKGROUND

Correlation between clinical features and magnetic resonance imaging (MRI) findings is essential in low-back-pain patients. Most previous studies have analyzed concordance in the interpretation of lumbar MRI among a few radiologists who worked together. This may have overestimated concordance.

PURPOSE

To evaluate intra- and interobserver agreement in the interpretation of lumbar MRI performed in an open 0.2 T system.

MATERIAL AND METHODS

Seven radiologists from two different geographic settings in Spain interpreted the lumbar MRIs of 50 subjects representative of the general Danish population aged 40 years. The radiologists interpreted the images in routine clinical practice, having no knowledge of the clinical and demographic characteristics of the subjects and blinded to their colleagues' assessments. Six of the radiologists evaluated the same MRIs 14 days later, having no knowledge of the previous results. Data on the existence of disc degeneration, high-intensity zones, disc contour, Schmorl nodes, Modic changes, osteophytes, spondylolisthesis, and spinal stenosis were collected in the Nordic Modic Consensus Group Classification form. Intra- and interobserver agreement was analyzed for variables with a prevalence >or=10% and <or=90% by means of the kappa statistic.

RESULTS

Intra- and interobserver agreement was excellent for variables related to Modic changes, and fair to good for disc contour, high-intensity zones, and Schmorl nodes. The evaluations for disc degeneration and osteophytes were found to have fair to good intraobserver agreement and poor interobserver agreement. The agreement for the evaluations of spondylolisthesis and spinal stenosis was not analyzed because they were observed in <10% of reports.

CONCLUSION

Images from 0.2 T MRIs appear to lead to good agreement in the reporting of disc contour, high-intensity zones, Schmorl nodes, and, in particular, Modic changes, suggesting that they can possibly be reliably used for clinical research purposes. In contrast, assessment of osteophytes and disc degeneration is not reliable.

Responsive viscoelastic giant lipid vesicles filled with a poly(N-isopropylacrylamide) artificial cytoskeleton

Responsive giant lipid vesicles filled with aqueous PolyNipam sol (SFV) or gel (GFV) were prepared by ultra-violet polymerisation performed in situ. Upon crossing the lower critical transition temperature of PolyNipam, SFVs and GFVs undergo a significant change of their structural and mechanical properties or a drastic volume transition, respectively. Rheometric and micropipette experiments show that both internal viscosity of SFVs and internal shear modulus of GFVs are tunable over several orders of magnitude and lie in the range observed for living cells. Moreover, the vesicle membrane is strongly bound to the internal polymer medium, making these systems interesting for mimicking the basic mechanical behaviour of passive living cells.

Breakfast, plasma glucose and beta-hydroxybutyrate, body mass index and academic performance in children from Extremadura, Spain

OBJECTIVES

Nutritional aspects of breakfast, plasma levels of glucose and beta-hydroxybutyrate, body mass index and academic performance have been studied in urban and rural children (Extremadura, Spain).

METHODS

Representative samples of schoolchildren (3 to 12 years old, random cluster-sampling in schools).

RESULTS

Children's mean caloric intake with breakfast was 331 kcal. Rural population ingested more carbohydrates (46,9 +/- 12,3% versus 43,3 +/- 13,2% of the total caloric intake) and fewer lipids (40,5 +/- 11,8% versus 43,9 +/- 12,8% of the total caloric intake) than the urban population. Academic performance was significantly better in the children inhabiting the rural zone than in those of the urban zone. The glycaemia was higher in the urban than in the rural children, and that the contrary was the case for the beta-hydroxybutyrate values. Neither glucose nor beta-hydroxybutyrate levels were correlated with academic performance values. BMI was significantly increased in the urban versus rural children.

CONCLUSION

The present results emphasize the importance of breakfast and life style in the weight and the academic performance of children.

Primidone is associated with interictal depression in patients with epilepsy

Depressive symptoms are common in epilepsy. To determine associations between depression and demographic, clinical, and pharmacological factors among epileptic patients, we conducted a cross-sectional survey. We evaluated 241 epileptic outpatients at a neurological center in a 6-month period. Depressive syndrome was diagnosed when both the Montgomery-Asberg Scale and the Beck Depression Inventory were rated above the standard cutoff points. Bivariate and multivariate analyses were performed to assess the differences between depressed and nondepressed patients with respect to demographic, clinical, and pharmacological features. Depressive syndrome was diagnosed in 42.7% of patients (n=103). Factors associated in the bivariate analysis were: cryptogenic etiology, posttraumatic epilepsy, use of primidone, and inadequate seizure control. After logistic regression, inadequate seizure control (OR 3.08, 95% CI 1.40-6.77, P=0.005) and use of primidone (OR 4.08, 95% CI 2.09-7.98; P<0.001) remained significantly associated. Depression was common and associated with inadequate seizure control and use of primidone.

Lack of association of apolipoprotein E polymorphism in obsessive-compulsive disorder

Obsessive-compulsive disorder (OCD) could be considered a neurodevelopmental disorder, from several lines of evidence. One of the most widely studied genes in these disorders is the apolipoprotein E gene, particularly allele 4. We analyzed for association among patients with OCD versus normal controls and cognitively impaired patients. There were no significant differences between OCD probands compared with population controls. However, the cognitively impaired group showed a higher frequency of allele apolipoprotein E gene compared with normal controls and patients with OCD.

[Calcium intake among school children in Badajoz]

BACKGROUND

The intake of calcium has been studied in the diet of adolescents from a school in Badajoz (Spain) determining their BMI and their living habits (sport, consumption of tobacco and alcohol).

METHODOLOGY

By means of an aleatory sampling, a sample n was selected = 207 (49.76% males and 50.24 females) with an average age of 14.14 +/- 2.08 years. They were weighed and measured to calculate their BMI. A questionnaire was carried out on consumption of products rich in calcium: milk and dairy produce, vegetables, fruit, chied fruits. The statistical analysis was carried out by means of Student t and ANOVA.

RESULTS

The results was BMI < 25 (thin or standard) in 86.47%; BMI 25-30 (overweight) in 10.63% and BMI > 30 (overweight) 2.9%. The consumption of daily calcium was of 1304 +/- 702 g/ppd, higher (p < 0.001) in boys (10.45 +/- 5.51) than in girls (7.82 +/- 3.84). There is not correlation between BMI and calcium consumption. The boys observe the NIH recommendations. But girls usually don't. Milk products provide 87% of the consumed calcium. The boys who practice some sports consume 9.88 +/- 5.23 g/pps, the other ones 7.09 +/- 2.95 g/pps.

CONCLUSIONS

1. The weekly intake of calcium by surveyed students is 9.13 g/pps, smaller in girls than in boys. 2. Milk products provide 87% of the consumed calcium. 3. A 10.63% of them is overweight and a 2.9% is very overweight. 4. A 10.63% usually smokes and a 20.29% consumes alcohol. 5. A 26.27% doesn't practice any sports and consumes less calcium (p < 0.001) than the recommended quantity.

Problems associated with hazardous and harmful alcohol consumption in Mexico

This chapter presents research findings from a collaborative project between Mexican investigators from the Mexican Institute of Psychiatry and the World Health Organization on the identification and treatment of harmful and hazardous drinking. A sample of 189 individuals who met criteria for hazardous drinking was selected for the study after screening 2319 outpatients attending clinics in two general hospitals in Mexico City. We present here the characteristics of this sample along dimensions that include alcohol related problems, history of trauma, alcohol dependence scores and family history of alcoholism. We rated, utilizing structures interviews, situations that place these individuals at risk of drinking. The possibility of constructing a typology of harmful and hazardous drinking was also explored. The significance of the findings of this investigation for health care clinicians is discussed.

Alcoholic beverage consumption in India, Mexico, and Nigeria: a cross-cultural comparison

Drinking practices vary substantially among different countries. An understanding of such differences can help researchers, clinicians, and policymakers develop prevention, diagnostic, and treatment measures as well as overall alcohol policies that are appropriate for a given country. Accordingly, researchers have conducted cross-cultural analyses of drinking patterns and practices. Three countries included in such analyses are India, Mexico, and Nigeria. These countries differ substantially in their ethnic and cultural characteristics, including the role that alcohol plays in daily life. To gain a better insight into the attitudes toward alcohol in these countries, researchers have analyzed the alcoholic beverage preferences, gender and age differences in alcohol consumption patterns, drinking contexts and drinking patterns, alcohol-related problems, approaches to prevention and treatment, and drinking indicators in each nation. These analyses demonstrate that no single definition of "normal" drinking, problem drinking, or alcohol dependence can apply equally to all countries or cultures.