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The authors discuss the main climate change impacts on pastoralist societies, including those on rangelands, livestock and other natural resources, and their extended repercussions on food security, incomes and vulnerability. The impacts of climate change on the rangelands of the globe and on the vulnerability of the people who inhabit them will be severe and diverse, and will require multiple, simultaneous responses. In higher latitudes, the removal of temperature constraints might increase pasture production and livestock productivity, but in tropical arid lands, the impacts are highly location specific, but mostly negative. The authors outline several adaptation options, ranging from implementing new technical practices and diversifying income sources to finding institutional support and introducing new market mechanisms, all of which are pivotal for enhancing the capacity of pastoralists to adapt to climate variability and change. Due to the dynamism of all the changes affecting pastoral societies, strategies that lock pastoral societies into specified development pathways could be maladaptive. Flexible and evolving combinations of practices and policies are the key to successful pastoral adaptation.

Les auteurs examinent les principaux effets du changement climatique sur les sociétés pastorales, en particulier ceux qui affectent les prairies, le bétail et d'autres ressources naturelles ainsi que les répercussions durables sur la sécurité alimentaire, sur les revenus et sur la vulnérabilité des populations. Le changement climatique va profondément et diversement affecter les prairies de la planète et le degré de vulnérabilité des personnes qui y vivent, ce qui imposera de déployer des réponses multiples et simultanées. Si dans les latitudes plus élevées, la suppression de certaines contraintes liées aux températures permet d'augmenter la production d'herbage et d'accroître la productivité du bétail, dans les terres arides tropicales les effets du climat, très spécifiques selon les endroits, sont majoritairement négatifs. Les diverses solutions adaptatives mises en avant par les auteurs, depuis la mise en oeuvre de nouvelles techniques et la diversification des sources de revenus jusqu'à la recherche de soutiens institutionnels et la création de nouveaux mécanismes de marché, sont toutes déterminantes pour améliorer la capacité des pasteurs à s'adapter à la variabilité et au changement climatiques. En raison du caractère dynamique des changements affectant les sociétés pastorales, les stratégies consistant à confiner ces sociétés dans des tracés spécifiques de développement risquent de s'avérer contreproductives en termes d'adaptation. Un assortiment souple et évolutif de pratiques et de politiques est la clé d'une adaptation pastorale réussie.

Los autores examinan los principales efectos del cambio climático sobre las sociedades pastorales, en particular los que afectan a las tierras de pasto, el ganado y otros recursos naturales, así como sus repercusiones más indirectas sobre la seguridad alimentaria, los ingresos y la vulnerabilidad. El cambio climático traerá consigo diversos efectos de gravedad que influirán en los pastizales del planeta y la vulnerabilidad de quienes viven de ellos, efectos que exigirán múltiples respuestas simultáneas. En altas latitudes, la desaparición de las limitaciones ligadas a la temperatura podría deparar una mayor producción de los pastizales y con ello una mayor productividad del ganado, pero en las tierras áridas tropicales los efectos dependerán en gran medida de las condiciones de cada localidad y serán mayormente negativos. Los autores destacan varias posibilidades de adaptación, desde la aplicación de nuevos procedimientos técnicos y la diversificación de las fuentes de ingresos hasta la obtención de apoyo institucional, pasando por la instauración de nuevos mecanismos de mercado, todas ellas soluciones cruciales para dotar a las sociedades de pastores de mayor capacidad de adaptación a la variabilidad y la evolución del clima. Teniendo en cuenta el dinamismo de cuantos cambios afectan a las sociedades pastorales, toda estrategia que las encorsete en una u otra vía específica de desarrollo podría resultar inadaptada. La clave para una adaptación fructífera de esas sociedades estriba en combinaciones de prácticas y políticas que sean flexibles y evolucionen en el tiempo.

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OBJECTIVE: The objective of this study was to assess bone mineral density (BMD) on a cohort of women who used depot medroxyprogesterone acetate (DMPA) (Depo-Provera) contraception uninterruptedly between 3 and 10 years. DESIGN: Retrospective study with review of the literature. SETTINGS: Office gynecology Velké Mezirící; Osteocentrum Brno; Department of Obstetrics and Gynecology, Hospital Nové Mesto na Morave. METHODS: The study included 21 healthy women aged between 26 and 43 years (the mean age 31 years) who started long-term continual application of depot medroxyprogesterone acetate (DMPA) in contraception (Depo-Provera) (the mean time of using 7 years, range 3-10 years). The women underwent lumbar spine, hip, femoral neck and forearm BMC (g) (bone mass content), BMD (g/cm2)(bone mass density), T-score, PR (%) (peak reference), Z-score, AM (%)(age matched) evaluation using Hologic dual-energy X-ray absorptiometry. Age of women, time of application of Depo-Provera and body mass index (BMI) were collected. Randomly from this cohort of users DMPA (n = 11) were determined levels of serum folicle stimulating hormone (FSH) and estradiol (E2), mostly shortly before next application of DMPA. RESULTS: At average 7 years of treatment, as compared to baseline, the mean BMD of DMPA users was in total lumbar spine AM (age matched) 96.48%, total hip AM 100%, femoral neck AM 97.62%, total forearm (radius+ulna) AM 99.81%. Concentrations of serum estradiol varied from 94.3-294 pmol/l (25.7-80.1 pg/ml) with average level 190.3 pmol/l(51.9 pg/ml), seen in the early follicular phase. CONCLUSION: There are probably several reasons, but not at least, why mean bone loss even after long use of DMPA is low. The loss of BMD is more pronounced during the first 2 years of use DMPA and its fall subsequently gradually stabilises due to new balance between extrinsic and intrinsic factors that influence bone resorption and formation. After the two years bone loss in DMPA users nears under 1% per year and practically copies level of physiological bone loss. Another hypothetical compensation mechanisms of bone remodelling in the hypoestrogenic time during DMPA use may be reason of higher levels of BMD 4-5 years after discontinuing the use of contraceptive injections than that of nonusers (rebound phenomenon).

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STUDY OBJECTIVES: To define the clinical profile of young adults with optimal low-density lipoprotein (LDL) cholesterol levels who present with acute myocardial infarctions (MIs); to compare and contrast differences in the clinical profiles of young adults admitted to the hospital with MIs who have LDL cholesterol levels < or = 100 mg/dL and those with LDL cholesterol values > or = 160 mg/dL; and to evaluate the clinical outcomes for the two groups at 1 year. DESIGN: A retrospective chart review was conducted on all young men (55 years) and women (65 years) admitted to the hospital for MIs within a 2-year period (n = 232). A history of cardiovascular risk factors and 1-year outcomes were obtained. SETTING: Rural community medical center serving a tri-state area in the midwestern United States. PATIENTS: Patients were included in this analysis if (1) a lipid profile was drawn within 24 h of hospital admission and (2) the patient was not receiving a statin medication on hospital admission. MEASUREMENTS AND RESULTS: Of the 183 patients who met the inclusion criteria, as many as 68% (124 patients) had LDL cholesterol levels of < or = 130 mg/dL, 29% (53 patients) had LDL cholesterol level of < or = 100 mg/dL, and only 14% (26 patients) had LDL cholesterol levels of > or = 160 mg/dL. Patients were categorized into group 1 if their LDL cholesterol level was < or = 100 mg/dL and were categorized into group 2 if their LDL cholesterol level was > or = 160 mg/dL. In group 2, 92% of patients were placed on a statin medication. By 1 year, the mean LDL cholesterol level had decreased from 188 to 106 mg/dL. The rate of coronary artery bypass graft and percutaneous coronary intervention procedures was similar between groups. Hospital readmission rates (43.4% vs 50%, respectively) and 1-year mortality rates (9% vs 8%, respectively) were not different between groups group 1 and 2. CONCLUSIONS: Young adults experiencing acute MIs typically have acceptable cholesterol levels (ie, < or = 130 mg/dL) or optimal values (ie, < or = 100 mg/dL). In those patients with abnormal cholesterol levels, a combined strategy of aggressive intervention and adherence to secondary prevention protocols including lipid control is successful in improving outcomes.

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BACKGROUND: The aim of this study was to determine the incidence of congestive heart failure (CHF) in patients discharged from a hospital without a diagnosis of CHF who were admitted with shortness of breath and had a low left ventricular ejection fraction (LVEF). CHF is a devastating disease in terms of financial cost, prevalence, and effect on morbidity and mortality. The true incidence rate is not known because of reliance on discharge records and death certificates, and because diagnosis remains a clinical judgment. METHODS AND RESULTS: CHF was diagnosed by the Framingham criteria. We retrospectively reviewed the records of 225 randomly selected patients admitted with a complaint of shortness of breath and discharged without a diagnosis of CHF (group 1). We compared group 1 with patients admitted at the same time with a diagnosis of CHF and of similar age and LVEF (group 2). In group 1, 100 patients had a low LVEF (< or =40%) and 51% met criteria for CHF that had been missed. Readmission rate was high (42%). Mortality at 12 months was 18%. Rate of cardiomegaly on x-ray films was similar in groups 1 and 2 (64.6% v 64.4%, respectively). Third heart sound (39% v 10%; P <.001) and heart rate > 120 beats/min (41.7% v 12.5%; P <.001) were significantly more frequent in group 1. By contrast, signs and symptoms suggestive of fluid overload were more frequent in group 2. CONCLUSIONS: Many patients admitted with shortness of breath and low LVEF have CHF but are not diagnosed. Physicians are more likely to miss CHF in patients presenting without signs of fluid overload even when third heart sound is present with resting tachycardia. A missed diagnosis of CHF is associated with a high readmission rate, multiple admissions, and a mortality rate comparable to that of patients with newly diagnosed CHF.

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The purpose of this study was to examine the effects of prolonged hypoxia on adipose tissue lipolysis, in relation to the weight loss usually observed at high altitude. Eight male subjects were exposed for 31 days to gradually increasing hypobaric hypoxia up to the equivalent altitude of 8848 m (Mt Everest) in a decompression chamber, after 7 days at 4350 m for altitude pre-acclimatization. A biopsy of subcutaneous adipose tissue was performed before and after hypoxic exposure, to study in vitro changes in adipose tissue sensitivity. Fat mass, adipocyte volume and spontaneous lipolysis were not impaired by the exposure to hypoxia. The in vitro lipolytic response to epinephrine, isoproterenol, growth hormone (GH) and parathormone (PTH) decreased significantly (P<0.01, P<0.05, P<0.01 and P<0.01 respectively), as did the plasma concentration of free fatty acid (P<0.01). The anti-lipolytic effect promoted by alpha2-adrenergic receptor stimulation (epinephrine with propranolol) was greater after hypoxia (P<0.05), while the anti-lipolytic activity of insulin was decreased (P<0.01). In conclusion, prolonged exposure to hypobaric hypoxia led to a potent reduction in lipid mobilization, through a decrease in the efficiency of beta-adrenergic, GH and PTH lipolytic pathways, as well as an increment in the alpha2-adrenergic-receptor-mediated anti-lipolytic effects.

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The influence of the Wankel type semipulsatile left ventricular assistance on hemodynamics was investigated with a computer simulation and an animal experiment. A simulation circuit was constructed to express the circulatory system. A current source was added to create a semipulsatile blood pump. The left and right ventricles were replaced by variable compliances. Left heart failure was simulated by decreasing the amount of compliance change of the left ventricle. Under the condition of heart failure when semipulsatile assist flow increased, the mean aortic pressure (AoP), tension time index (TTI), and diastolic pressure time index (DPTI) increased, and the cardiac output, pulse pressure (PP), and pulsatility indicator (PI) decreased. In an animal experiment, a Wankel type blood pump was used in a calf. With the increase of the assist flow, AoP curves became less pulsatile, and PP and PI decreased in accordance, which was predicted by the numerical simulation.

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Our group is developing a left ventricular assist device based on the principle of the Maillard-Wankel rotative compressor: it is a rotary, not centrifugal, pump that produces a pulsatile flow. Stringent requirements have been defined for construction materials. They must be light, yet sufficiently hard and rigid, and able to be machined with high precision. The friction coefficient must be low and the wear resistance high. The materials must be chemically inert and not deformable. Also, the materials must be biocompatible, and the blood contacting surface must be hemocompatible. We assessed the materials in terms of physiochemistry, mechanics, and tribology to select the best for hemocompatibility (determined by studies of protein adsorption; platelet, leukocyte, and red cell retention; and hemolysis, among other measurements) and biocompatibility (determined by measurement of complement activation and toxicity, among other criteria). Of the materials tested, for short- and middle-term assistance, we chose titanium alloy (Ti6Al4V) and alumina ceramic (Al2O3) and for long-term and permanent use, composite materials (TiN coating on graphite). We saw that the polishing process of the substrate must be improved. For the future, the best coating material would be diamond-like carbon (DLC) or crystalline diamond coating.

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The morphology of Al2O3, ZrO2/Y2O3, AIN, B4C, BN, SiC, Si3N4, TiB2, TiC, TiN ceramic, graphite and diamond powders has been studied by scanning electron microscopy (SEM) and the specific area of each powder was determined with the BET method. X-ray diffraction (XRD) investigations have been carried out in order to evaluate the crystallinity and determine the constitutive phases. The chemical composition was assessed by classical chemical analyses and by X-ray microprobe; some powders were studied by the laser micro-Raman technique. Correlations have been established between all these results.

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Data from animal experiments with mechanical circulatory support systems (MCSS) performed in Groningen and Marseille over the past years were used to obtain normal values of hematological, coagulation, rheological and blood chemistry parameters in calves. These parameters were divided between two groups: a limited number of parameters necessary to assess biocompatibility properties of MCSS quickly and a more extensive number of parameters suitable for more detailed biological evaluation of blood pumps. All applied tests can be examined in calf blood as well as in human blood. Parameters were selected on clinical relevance and usefulness for standardization procedures. The obtained data were compared with normal values in human beings derived from the literature.

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For decades, research for developing a totally implantable artificial ventricle has been carried on. For 4 to 5 years, two devices have been investigated clinically. For many years, we have studied a rotary (but not centrifugal) pump that furnishes pulsatile flow without a valve and does not need external venting or a compliance chamber. It is a hypocycloidal pump based on the principle of the Maillard-Wankel rotary compressor. Currently made of titanium, it is activated by an electrical brushless direct-current motor. The motor-pump unit is totally sealed and implantable, without noise or vibration. This pump was implanted as a left ventricular assist device in calves. The midterm experiments showed good hemodynamic function. The hemolysis was low, but serious problems were encountered: blood components collecting on the gear mechanism inside the rotor jammed the pump. We therefore redesigned the pump to seal the gear mechanism. We used a double system to seal the open end of the rotor cavity with components polished to superfine optical quality. In addition, we developed a control system based on the study of the predicted shape of the motor current. The new design is now underway. We hope to start chronic experiments again in a few months. If the problem of sealing the bearing could be solved, the Cora ventricle could be used as permanent totally implantable left ventricular assist device.

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We tested our valveless pulsatile rotary blood pump (CORA) extensively in animals, but only as a temporary implantable left ventricular assist device. To expand the scope of future clinical applications, we recently undertook experiments to assess the feasibility of our pump for use in a standard cardiopulmonary bypass circuit. We conducted 4 experiments in adult sheep (body weight, 40 kg): 2 with CORA and 2 with the BioMedicus pump (BP) for comparison. In all experiments, a currently used extracorporeal circuit with reservoir, filter, and membrane oxygenator (Sorin monolith) was installed, and open chest extracorporeal circulation (ECC) was performed for 6 h. Hemodynamic performance and hemolysis were evaluated. CORA provided semipulsatile systemic flow at a level comparable to that of the BP. Free plasma hemoglobin levels were slightly higher with CORA, but the decrease in platelet count was the same for both devices. There was no significant difference in the extent of blood trauma. We conclude that CORA could be successfully used for ECC with an oxygenator. Negative pressure can be prevented by our specially designed control system.

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We have developed a low-speed, double-lobed hypocycloidal pump that furnishes a pulsatile flow without valves. The pump is coupled to a specially designed electric motor. The motor/pump unit is totally implantable and has been extensively tested in vitro and in vivo in animals. Because this pump is volumetric, it is necessary to control speed precisely to avoid overpumping. Our control system, which is based on analysis of the motor current wave form, can detect and prevent negative pressures before they occur. The physical properties and hemocompatibility of several construction materials have been studied to determine their suitability for clinical use. These materials include a graphite substrate, titanium nitrate surface coating, boric carbon, and amorphous diamond. The pumps currently being tested are made of titanium, but clinical versions will be made of composite materials selected from this preliminary study. In vivo testing of this pump confirmed its good hemodynamic performance, low hemolysis rate, and biocompatibility (i.e., low heat, noise, and vibration levels). Animal experiments were terminated after 15 days because of mechanical failure related to the accumulation of blood components on moving parts. A new pump in which the mechanism is completely sealed from the blood flow has been designed and will soon be tested. If this sealed design is effective, the pump should be ready for use as a permanent implantable ventricular assistance device.

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Lumbar bone mineral content (BMC) of 33 female patients aged 14-30 years (19 +/- 4.1 (mean +/- SD) with anorexia nervosa (duration 31 +/- 37 months) was studied using dual X-ray absorptiometry. Results were compared with the data obtained in a population of 26 women aged 17-38 years without bone disease. BMC was significantly decreased (0.872 +/- 0.107 g/cm2 hydroxyapatite) in anorectic patients as compared to controls (1.008 +/- 0.098 hydroxyapatite). A single patient had a non traumatic vertebral compression fracture. A statistically significant negative correlation was found between BMC and duration of amenorrhea (r = 0.48; p < 0.01). There was no significant correlation between BMC and body mass index or daily calorie intake. Ovarian steroid deficiency might thus be a major factor--among other ones--in the development and the degree of bone loss in anorexia nervosa.

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Our ventricular assist device uses a valveless volumetric pump operating on the Maillard-Wankel rotary principle. It is driven by an electric motor and provides a semi pulsatile flow. At each cycle, blood is actively aspirated into the device, and overpumping results in collapse at the pump inlet. To prevent overpumping, it is necessary to ensure that pump intake does not exceed venous return. Poor long-term reliability rules out the use of current implantable pressure sensors for this purpose. To resolve this problem, we have developed a method of control based on monitoring of the intensity of electric current consumed by the motor. The method consists of real time monitoring of current intensity at the beginning of each pump cycle. A sudden change in intensity indicates underfilling, and motor speed is reduced to prevent collapse. The current consumed by the motor also depends on the afterload, but the form of the signal remains the same when afterload changes. After demonstrating the feasibility of this technique in a simulator, we are now testing it in animals. We were able to detect and prevent collapse due to overpumping by the cardiac assist device. This system also enables us to know the maximum possible assistance and to thus adapt assistance to the user.

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In order to evaluate under dynamic circumstances the in vitro platelet adhesion induced by rigid materials such as ceramic coatings deposited on selected substrates, a new model simulating a tube has been designed. In vitro platelet adhesion was assessed with this new model: the material was titanium nitride (TiN) deposited on Ti6A14V (TA6V) titanium alloy by a physical vapor deposition (PVD) process. The results were compared to those obtained with complete titanium carbide (TiC) graphite tubes coated with TiN by a chemical vapor deposition (CVD) process. The difference observed (less than 25%) in favour of the new system, could be due to the better surface state of the construction materials of this system. In fact it is a systemic error. However TiN confirms its good performance as a blood-contacting biomaterial.

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The left ventricular assist device under consideration is based on the principle of the Maillard-Wankel rotary pump. The construction materials must meet stringent requirements. Titanium nitride was chosen for its surface properties and graphite for its bulk characteristics. The purpose of this study was to characterize the chemical vapour deposition titanium nitride coating via morphology, roughness, crystallinity, chemical composition, to report and discuss the results of in vitro haemocompatibility tests (protein adsorption, platelet retention, haemolysis) and to discuss physico-chemical and biological results. This chemical vapour deposition titanium nitride coating is well tolerated by the blood despite its surface irregularities, and appears as a good candidate material after improvements.

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Ti6A14V alloy has been mainly used as a biomaterial in the orthopaedic field. The present study describes the surface state of the Ti6A14V material and evaluates its in vitro haemocompatibility in terms of protein adsorption, platelet retention and haemolysis. The behaviour of the Ti6A14V alloy towards albumin and fibrinogen was compared to that of a reference medical-grade elastomer. The platelet retention test gave better results than those achieved with the elastomer. The haemolysis percentage of the alloy was almost zero. These results indicate that the Ti6A14V alloy is well tolerated by blood.

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Ceramics are more and more frequently under consideration for construction of blood-contacting devices, i.e. cardiac valves or cardiac assist devices. This study evaluated the haemolysis eventually initiated in vitro by ceramic powders (Al2O3, ZrO2/Y2O3, AlN, B4C, BN, SiC, Si3 N4, TiB2, TiN, TiC), graphite and diamond. The chemical composition of the powders was studied by X-ray microprobe and various other methods, and BET specific areas were determined. The haemolysis was almost zero for all powders, except AlN which showed slight haemolysis and TiB2 which had high haemolytic power.

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The authors' laboratory is developing a device for heterotopic left ventricular assistance. It consists of a titanium Wankel-type rotary pump, driven by an hermetically sealed electric motor. In our animal experiments, the motor-pump unit was implanted in the thoracic wall. The pump was connected to the left heart chambers by left atrial cannulation, and to the descending aorta. The motor was connected to the power and control unit by an electric wire through the skin. In this report, the authors describe the first significant animal survival with this system. Laboratory results were encouraging for hemolysis. The pump failed at 13 days due to a deposit of fibrin and blood cells in the gear housing. This problem was not surprising since similar events have been encountered with centrifugal devices. However, further design improvements should allow longer animal survival and clinical application.

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