Tug-of-war between stretching and bending in living cell sheets.

The balance between stretching and bending deformations characterizes shape transitions of thin elastic sheets. While stretching dominates the mechanical response in tension, bending dominates in compression after an abrupt buckling transition. Recently, experimental results in suspended living epithelial monolayers have shown that, due to the asymmetry in surface stresses generated by molecular motors across the thickness e of the epithelium, the free edges of such tissues spontaneously curl out-of-plane, stretching the sheet in-plane as a result. This suggests that a competition between bending and stretching sets the morphology of the tissue margin. In this paper, we use the framework of non-Euclidean plates to incorporate active pre-strain and spontaneous curvature to the theory of thin elastic shells. We show that, when the spontaneous curvature of the sheet scales like 1/e, stretching and bending energies have the same scaling in the limit of a vanishingly small thickness and therefore both compete, in a way that is continuously altered by an external tension, to define the three-dimensional shape of the tissue.

A unified rheological model for cells and cellularised materials.

The mechanical response of single cells and tissues exhibits a broad distribution of time-scales that often gives rise to a distinctive power-law rheology. Such complex behaviour cannot be easily captured by traditional rheological approaches, making material characterisation and predictive modelling very challenging. Here, we present a novel model combining conventional viscoelastic elements with fractional calculus that successfully captures the macroscopic relaxation response of epithelial monolayers. The parameters extracted from the fitting of the relaxation modulus allow prediction of the response of the same material to slow stretch and creep, indicating that the model captured intrinsic material properties. Two characteristic times, derived from the model parameters, delimit different regimes in the materials response. We compared the response of tissues with the behaviour of single cells as well as intra and extra-cellular components, and linked the power-law behaviour of the epithelium to the dynamics of the cell cortex. Such a unified model for the mechanical response of biological materials provides a novel and robust mathematical approach to consistently analyse experimental data and uncover similarities and differences in reported behaviour across experimental methods and research groups. It also sets the foundations for more accurate computational models of tissue mechanics.

[Targeted screening of COPD in primary care: Feasibility and effectiveness]. / Détection précoce de la BPCO en soins primaires : un essai contrôlé randomisé.

INTRODUCTION: Chronic obstructive pulmonary disease (COPD) is a common but under-diagnosed pathology in primary care. The objective was to study the feasibility of a randomized controlled trial in general practice to detect new cases of COPD at an earlier stage. METHODS: A cluster randomized, controlled, multicenter intervention study comparing, according to a 2×2 factorial plan, two case finding strategies: a systematic GOLD-HAS hetero-questionnaire and coordination of the patient's path to facilitate access to spirometry. The PIL-DISCO pilot study took place in 2017. Patients between 40 and 80 years old, with no previous history of COPD, consulting their GP on a given day regardless of the reason, were included. RESULTS: 176 patients were included in 1.5 days. Spirometry was performed in none of the control arm, in 13 (29.5%) of the questionnaire arm, in 22 (50%) in the coordination arm and in 32 (72.7%) with the combination of the two strategies. Two cases of stage 2 COPD and thirteen other respiratory diseases were diagnosed. CONCLUSIONS: This study confirms the feasibility of the protocol in primary care in terms of speed of inclusion and acceptability. An extension phase aiming to include 3200 patients will assess the diagnostic value of the two strategies tested in general practice.

[Prevalence of HIV and hepatitis B and C among drug addicts in the city of Copenhagen]. / Udbredelsen af hiv og hepatitis B og C blandt københavnske stofmisbrugere.

Blood samples were drawn from 291 drug users attending methadone clinics throughout 1997 and interviews performed about associated risk factors for seroconversion. The overall prevalence of HIV was 3.4%. Sixty-four percent tested positive for HBV and 75% for HCV. Almost all with a ten year history of drug use acquired one or more of the infections, including those who reported not to have injected. Among the sexually active 54% never used a condom and 14% of the injectors had shared needles within the last six months. Prevention measures contributing to the low prevalence of HIV had apparently no effect on transmission of hepatitis B and C. The findings call for more focus on hepatitis prevention including information, counselling, testing and vaccination.

[Pericardial and myocardial adiastole in rheumatoid polyarthritis]. / Adiastolie péricardique et myocardique au cours d'une polyarthrite rhumatoïde.

The authors describe a case of clinical, echocardiographic and haemodynamic adiastole in a man with severe rheumatoid arthritis with a previous history of pericardial effusion. The adiastole was mixed, fibrous pericarditis, confirmed by ultra fast CT scan and at surgery; myocardial adiastole was suspected on finding thickening of the ventricular walls (in the absence of hypertension and coronary artery disease) and, unfortunately, confirmed by the persistence of adiastole despite very satisfactory pericardectomy. The authors underline the involvement of the three cardiac tunics in rheumatoid arthritis and the value of different diagnostic methods in the differentiation between constrictive pericarditis and restrictive cardiomyopathy.

[Bartonella quintana endocarditis. Aortic localization and mitral valve abscess]. / Endocardite à Bartonella quintana. Localisation aortique et abcès mitral.

Bartonella Quintana is an exceptionally rare cause of endocarditis. The frequency of this condition is increasing and is probably underestimated because of the difficulty in diagnosing. The clinical context is that of socially deprived classes, the agent of transmission of the germ being body lice. The commonest valve affected is the aortic valve. This infection may also give rise to a mitral annulus abscess, as in this particular case. The diagnosis should be suspected in all cases of endocarditis with negative blood cultures in socially deprived patients as special diagnostic methods are required. Bartonellosis serology and drainage of effusions to perform a Gimenez stain to show intra-cellular bacteria and a polymerase chain reaction to sequence the nucleic acids, will give an accurate diagnosis. Similarly, the operative specimens should be sent to a specialised department for the culture of these bacteria (in France, the Marseille Ricketsioses Institute). The treatment of Bartonella endocarditis is very controversial. The usual recommendations are an association of betalactamines and an aminoside for one month and macrolides or tetracyclines. There is lack of consensus about follow-up. It would seem prudent to perform a clinical examination to search for a relapse of the infection and monthly serologies until they return to normal values.

[Knowledge, attitude and behavior among patients with Chlamydia. Perspectives for prevention]. / Viden, holdning og adfaerd blandt Chalamydia-patienter. Perspektiver for forebyggelsen.

Patients with chlamydial infections (Ct) attending the outpatient Venereal Disease Clinic of Copenhagen from July 1-November 30 1995 were asked to fill in a questionnaire focusing upon knowledge, attitude and behaviour related to sexually transmitted diseases (STDs) in order to strengthen the future prevention of Ct. The questionnaire was answered by 37 men and 35 women with a median age of 27 and 21 years and a median number of three and two sexual partners within the last six months, respectively. Half of the patients had previously had an STD, and 92% had been tested for HIV, of whom one homosexual man was known HIV-positive. Notification about exposure from a partner was the reason for attending for 24%. All but one were in favour of partner notification, but only 6% wanted provider referral. During last intercourse condoms had neither been used with a steady partner by 75% especially by the young and women, who thought themselves safe, nor with a casual partner by 52% especially among the young and men, mainly because of thoughtlessness or perception of low risk. Before the actual STD diagnosis only 49% were able to name one symptom and 35% one complication related to Ct. A majority (79%) stated, that fear of catching another Ct would lead to better protection, and 70% found that more information would have a preventive effect. Future Ct prevention programs in Denmark should include intensified chlamydial screening and partner notification together with centrally produced mass media information supplemented by individual counselling.

[Mitral surgery: prognostic and survival factors. Value of the French score]. / Chirurgie mitrale: facteurs de pronostic et de survie. Intérêt du score "français".

OBJECTIVES: Conservative mitral surgery is the preferred treatment for mitral regurgitation whatever the etiology. Morbidity and mortality figures, both during hospitalization and after long-term follow-up, are better than for mitral valve replacement. This difference could result from a selection bias or express a specific effect of conservative mitral surgery on survival. In addition, concerns about cost-containment justify rigorous analysis of treatment quality. The "French" score can be used for preoperative assessment of individual and population operative risk and for inter-institution comparisons. Its value for assessing overall survival is unknown. METHODS: Using the French score, we compared the clinical features and laboratory data in 100 patients who underwent conservative mitral valve surgery and in 35 patients who had valve replacement. We looked for independent factors predicting overall survival. RESULTS: Overall survival tended to be better after conservative mitral surgery, reaching 86% at 4 years versus 72% after replacement (p = 0.08). The populations were different as the valve replacement group included more women, was more symptomatic (p = 0.022), had heart failure more often (p = 0.003) and tended to have a higher French score (p = 0.06). Inversely, the hemodynamic and echocardiographic parameters were not different between the two groups. DISCUSSION: Independent factors predicting late mortality were preoperative heart failure and the French score. The type of mitral surgery did not have any predictive value. CONCLUSION: In addition to its value for assessing operative risk, the French score appears to be useful for predicting overall survival after mitral surgery.

[AIDS--the leading cause of death among young adult men in Copenhagen and Frederiksberg]. / AIDS--den førende dødsårsag blandt yngre, voksne moend i København og Frederiksberg.

The objective was to describe the extent to which HIV infection has become a major cause of death among young adults in Denmark. The design used was retrospective review of underlying causes of death recorded in the National Danish Register of Causes of Death on the basis of submitted death certificates. Analysis of mortality statistics revealed, that from 1980 to 1993 AIDS became the 5th leading cause of death among men 25 to 49 years of age in Denmark after cancer, accidents, suicide and heart disease. AIDS among women had little impact on the vital statistics in the period. In the municipalities of the City of Copenhagen AIDS was the major cause of death among men already from 1990 and in 1993 death from AIDS comprised 25% of all causes (n = 107, death rate = 88/100,000). The rising rates of deaths attributed to AIDS among younger men show no sign of decreasing neither in the capital nor in the country as a whole.

[Coxiella burnetti endocarditis on bioprosthesis. Apropos of a case]. / Endocardite à Coxiella burnetti sur bioprothèse. A propos d'un cas.

A patient with two bioprostheses was admitted to hospital with pyrexia and a small vegetation on the aortic bioprosthesis visible only on transoesophageal echocardiography without aortic incompetence. Blood cultures were negative. Serology to Coxiella burnetti was positive at high dilution and confirmed the diagnosis of infectious endocarditis. Medical therapy with doxycycline and chloroquine was instaured without surgery. A Coxiella burnetti infection should be systematically searched for in all cases of endocarditis with negative blood cultures. The features of this infection, particularly the aetiological circumstances, diagnosis, history and treatment are reviewed.

Sexual behaviour of gay and bisexual men in eight European countries.

To compare the sexual behaviour and HIV risk reduction strategies of gay and bisexual men in Europe, a survey, disseminated via the gay press and gay associations, was conducted amongst gay and bisexual men in Austria, Switzerland, Germany, Denmark, France, Great Britain, Italy and the Netherlands during the autumn and winter of 1991. By end March of 1992, 12,347 completed questionnaires had been obtained. A preliminary analysis shows striking similarities in patterns of sexual behaviour of gay men in the 8 European countries but indicates that strategies of risk management concerning HIV and AIDS vary widely. While the majority of gay men have multiple partners, and intercourse is more common with stable partners than with causal partners. The proportion of men who, during the past 12 months, engaged in unprotected anal intercourse with a partner with different or unknown HIV-status ranged from 1/3 in East Germany to 1/6 in UK. However, reported incidence over the past 12 months of STDs, other than HIV infection, was similar in all countries (2%-3%). The reported HIV antibody prevalence varied from less than 7% in East Germany, Italy and the United Kingdom to 15% in Denmark and 17% in France. HIV risk reduction strategies appear to be most common in those countries where the gay community had been included in targeted prevention campaigns during the early phase of the AIDS epidemic. Considering the high proportion of gay men engaging in high risk activities it is imperative that prevention efforts are sustained and improved.

Evaluating AIDS prevention for men having sex with men: the west European experience.

This article presents the major results of a Concerted Action of the European Community on "Assessing AIDS-prevention" concerning the male homo- and bisexual population. It discusses the methodologies and results of research projects undertaken in this area in the 1980's.

[Coronary embolism revealing mitral valve stenosis]. / Embolie coronaire révélatrice d'un rétrécissement mitral.

We report a case of myocardial infarction with normal coronary arteriography in a 39-year-old woman presenting with tight mitral stenosis complicated by atrial extrasystoles and spontaneous atrial contrast at echocardiography. The diagnosis of coronary embolism was most probable. Coronary embolism is a rare disease, usually due to a blood clot or, less frequently, to a vegetation of endocarditis starting in a heart valve. The left network is usually involved, with typical myocardial necrosis. Coronary arteriography is sufficient to make the diagnosis. Preventive treatment is essential.

[Changes of sexual behavior among Danish homo/bisexual men under the impact of HIV/AIDS epidemic]. / Aendringer i danske homo/biseksuelle maends seksualvaner som reaktion på HIV/AIDS-epidemien.

In October 1991, 1.567 gay/bisexual men throughout Denmark returned an anonymous questionnaire enclosed in the magazine of the National Gay and Lesbian Association. Most were younger, well educated men living in the Copenhagen area. 76% had been tested for HIV, 15% were infected. As in 1988, the median number of partners in 1991 was 2-5. Eighty-two percent of the sexually active men engaged in anal sex, of these half used condoms consistently. Anal sex was practised more with steady partners and condom use was more common with casual partners. One out of eight had engaged in unprotected anal intercourse with a partner with discordant HIV-serostatus, down from one in three in 1988. It is concluded, that Danish gay men have not further limited their sexual life during the later years. The majority of the respondents have increased sexual safety, but risky sex still prevails among a substantial minority, and safe sex campaigns should continue.

[Left pulmonary artery originating from the ascending aorta in tetralogy of Fallot. Therapeutic strategy]. / Artère pulmonaire gauche naissant de l'aorte ascendante dans une tétralogie de Fallot. Stratégie thérapeutique.

The authors report the rare case of a 12 year old child with an anomalous origin of the left pulmonary artery from the ascending aorta associated with Tetralogy of Fallot. This complex congenital malformation was treated surgically by a Deleval anastanosis between the right subclavian and right pulmonary arteries. The result was good with a 9 year follow-up, the patient having only Grade II effort duspnoea and cyanosis. The authors discuss the advantages and drawbacks of the different possible surgical approaches to this problem in the light of the outcome of this case and a review of the literature.

[Atrial flutter and tachy-systole]. / Flutter et tachysystolie auriculaires.

Atrial flutter and tachysystoles may complicate the course of all heart diseases or may be discovered independently of any detectable cardiopathy. Functional tolerance mainly depends on the presence and severity of the associated heart disease, if any. A regular cardiac rhythm of 150 beats/minutes at rest suggests a 2:1 block flutter. Electrocardiographic identification of the disorder is usually easy and may lead, in certain cases, to vagal manoeuvres to recognize the atriogramme and the atrium-ventricle relationship. In all cases, 2:1 flutters must be reduced with amiodarone, by electrical stimulation or by electric shock. A prophylactic treatment of recurrences is often, but not always, indicated. The treatment of tachysystoles must take into account the cause of the ventricular rate.

[Primary leiomyosarcoma of the pulmonary artery. Apropos of a case. Review of the literature]. / Léiomyosarcome primitif de l'artère pulmonaire. A propos d'un cas: revue de la littérature.

A 59-year-old woman hospitalised because of dyspnea and a heart murmur in a context of pyrexia was found to have evidence of obstruction of the pulmonary arterial system, clearly defined by ultrasonography, catheterisation and angiography and Imatron scan. The particular feature of this fifth reported case of pulmonary artery leiomyosarcoma is its documentation by transesophageal ultrasonography and tumor biopsy during catheterisation. Surgery with partial excision of the tumor was followed by survival for 6 months, bearing in mind the absence of chemo- or radiosensitivity of this type of tumor. Cases from the literature are reviewed.