Emerging responses to the COVID-19 crisis from family farming and the agroecology movement in Latin America - A rediscovery of food, farmers and collective action.

CONTEXT: In Latin America, the so-called informal sector associated with family farming and the agroecology movements were instrumental at coping with and adapting to the COVID-19 challenges. OBJECTIVE: To assess the nature and extent of the early initiatives (first three months) deployed by this informal sector to cope with and adapt to the impacts of the COVID-19 pandemic on food production and consumption in several countries of the region. METHODS: We used key used informant consultation (n = 168), an online survey (n = 125) and the detailed characterisation of regional case studies (n = 4). Textual data was analysed and categorised using Reinert's method, combined with similarity analysis. RESULTS AND CONCLUSIONS: 65% of the initiatives were 'local' in terms of geographic reach, 30% of them started within the first month after the pandemic and most of them were urban or urban-rural, whereas only 29% of them were exclusively rural. The analysis of the textual information captured through the survey revealed four major types of initiatives that were deployed or adapted in response to COVID-19:1.Direct producer-to-consumer food sales, generally existing before the COVID-19 crisis but adapted/strengthened to cope with it;2.Short value chains that linked rural and urban organisations and individuals supported by national or local governments, readapted through new health and safety protocols;3.Newly developed support and training programs on sustainable food production for self-consumption or local commerce, in rural, urban or peri-urban settings;4.Food assistance and aid initiatives focusing on vulnerable populations, relying on solidarity networks associated with the agroecological movement. SIGNIFICANCE: The pandemic highlighted the key role played by local food systems and value chains and the need to strengthening them through public policies, as a way to build food resilience in times of crisis.

Measurement of Identical Particle Entanglement and the Influence of Antisymmetrization.

We explore the relationship between symmetrization and entanglement through measurements on few-particle systems in a multiwell potential. In particular, considering two or three trapped atoms, we measure and distinguish correlations arising from two different physical origins: antisymmetrization of the fermionic wave function and interaction between particles. We quantify this through the entanglement negativity of states, and the introduction of an antisymmetric negativity, which allows us to understand the role that symmetrization plays in the measured entanglement properties. We apply this concept both to pure theoretical states and to experimentally reconstructed density matrices of two or three mobile particles in an array of optical tweezers.

Density Oscillations Induced by Individual Ultracold Two-Body Collisions.

Access to single-particle momenta provides new means of studying the dynamics of a few interacting particles. In a joint theoretical and experimental effort, we observe and analyze the effects of a finite number of ultracold two-body collisions on the relative and single-particle densities by quenching two ultracold atoms with an initial narrow wave packet into a wide trap with an inverted aspect ratio. The experimentally observed spatial oscillations of the relative density are reproduced by a parameter-free zero-range theory and interpreted in terms of cross-dimensional flux. We theoretically study the long-time dynamics and find that the system does not approach its thermodynamic limit. The setup can be viewed as an advanced particle collider that allows one to watch the collision process itself.

Anomalous Breaking of Scale Invariance in a Two-Dimensional Fermi Gas.

The frequency of the breathing mode of a two-dimensional Fermi gas with zero-range interactions in a harmonic confinement is fixed by the scale invariance of the Hamiltonian. Scale invariance is broken in the quantized theory by introducing the two-dimensional scattering length as a regulator. This is an example of a quantum anomaly in the field of ultracold atoms and leads to a shift of the frequency of the collective breathing mode of the cloud. In this work, we study this anomalous frequency shift for a two-component Fermi gas in the strongly interacting regime. We measure significant upwards shifts away from the scale-invariant result that show a strong interaction dependence. This observation implies that scale invariance is broken anomalously in the strongly interacting two-dimensional Fermi gas.

A severe case of haemodynamic instability during anidulafungin administration.

WHAT IS KNOWN AND OBJECTIVE: Anidulafugin is an echinocandin used for the treatment of candida infections in non-neutropenic adults. Echinocandins show few drug-drug interactions and are usually well tolerated. We report a case of acute hypotension, bradycardia and haemodynamic instability with consecutive cardiopulmonary resuscitation during anidulafungin administration. CASE SUMMARY: A 41-year-old man ICU patient received anidulafungin for a suspected Candida glabrata infection. During the first administration of the drug, he developed acute haemodynamic instability with hypotension and bradycardia. The infusion was discontinued immediately and cardiopulmonary resuscitation was performed successfully. The patient regained haemodynamic stability. WHAT IS NEW AND CONCLUSION: To the authors' knowledge, this is the first report of a life-threatening adverse event due to haemodynamic instability during anidulafungin administration. Cardiac toxicity associated with echinocandins has been described. Further studies seem to be mandatory to investigate this potential risk.

Effects of clinical audit on the quality of care in patients with type 2 diabetes: results of the DIABEST pilot study.

OBJECTIVE: To improve the quality of diabetes care in general practice by the use of audit. MATERIAL AND METHODS: A prospective multicenter pilot study. Thirty-five groups of ten general practitioners (GPs) have been set up throughout France on a voluntary basis. These groups were led by a steering committee that includes a diabetologist and a GP. Each group established a consensus on healthcare standards and carried out 2 data collections over a 12-month period, with adoption of corrective measures between these 2 collections. RESULTS: 309 (90.4%) of the 342 practitioners completed the first data collection, assessing the management of 3,125 patients over a year. Less than half the groups have reached the 80% reference threshold for quality of care with regard to foot examination, microalbuminuria, ECG, fundoscopy and assessment of diet. The audit also found no intervention within one year in case of poor glucose control for 47% of patients, unsatisfactory quality of HbA(1c) measurement and insufficient resources for diet and education. 226 (66.1%) practitioners completed the second data collection assessing the management of 2,248 patients. Comparison between the two phases of the audit showed significant improvements for all the indicators of the process of care (p<0.001). Quality of HbA(1c) measurement and diet assessment by GPs progressed (p<0.01). Outcomes of care also improved with respect to the proportion of patients with HbA(1c)<=8% (p=0.007), fasting glycaemia<1.40 g/l (p=0.05) and SBP<140 mmHg (p=0.02). CONCLUSIONS: This pilot study confirms the feasibility of using clinical audit at the national level. It seems to be an effective measure to improve the management of patients with type 2 diabetes in primary care. It is intended that the large-scale DIABEST study will address this issue.

Vinorelbine-gemcitabine in advanced non-small-cell lung cancer (NSCLC): an AASLC phase II trial. Austrian Association for the Study of Lung Cancer.

PURPOSE: The purpose of the present phase 11 trial was to determine the efficacy and toxicity of vinorelbine-gemcitabine in patients with advanced non-small-cell lung cancer (NSCLC). PATIENTS AND METHODS: From December 1997 to February 1999, 78 chemotherapy-naive patients (median age 60 years, Karnofsky performance status of 100, 90, 80 and 70 present in 5%, 41%, 36% and 18% of the patients, respectively) with stage IIIB (17%) or IV (83%) NSCLC (65% adenocarcinomas, 22% squamous-cell carcinomas, 10% large-cell carcinomas, 3% mixed-cell carcinomas) received 25 mg/m2 vinorelbine and 1200 mg/m2 gemcitabine on days 1, 8 and 15 of a four-week cycle. RESULTS: In an intent-to-treat analysis, partial responses were seen in 19% of the patients. The median duration of response was 4.4 months. The median survival time was seven months and the one-year survival rate was 32%. Myelosuppression was the main side effect with WHO grade 3/4 neutropenia and thrombocytopenia in 35% and 11% of the patients, respectively. Other side effects were usually mild to moderate. CONCLUSIONS: Vinorelbine-gemcitabine is active, well tolerated and easy to administer on an outpatient basis in advanced NSCLC. Thus a randomized comparison of this combination with platinum-based protocols is warranted in patients with advanced NSCLC.

Clinical autologous in vitro endothelialization of infrainguinal ePTFE grafts in 100 patients: a 9-year experience.

BACKGROUND: Clinical in vitro endothelialization was assessed for its ability to improve the long-term patency of prosthetic femoropopliteal bypass grafts. METHODS: Between June 1989 and May 1998, 100 patients received 113 in vitro endothelialized expanded polytetrafluoroethylene grafts (ePTFE). Bilateral implantations were performed in 13 patients. In phase 1 of the study, 24 patients received 27 endothelialized grafts and 16 patients received 17 untreated grafts. In phase 2, endothelialization was offered to all patients who did not have a suitable saphenous vein available. Phase 2 began in June 1993 and included 76 patients who received 86 endotheliazed ePTFE grafts. In all, 100 patients had autologous endothelial cells harvested from 4- to 5-cm segments of a subcutaneous vein. In phase 1, the external jugular vein was used. In phase 2, the cephalic vein was used. These cells were grown to first-passage mass cultures and were lined confluently onto 6-mm ePTFE grafts, pre-coated with fibrin glue. Patency assessment for Kaplan-Meier survivorship analysis was determined by using duplex sonography and angiography. RESULTS: In phase 1, the Kaplan-Meier method revealed a primary 9-year patency rate for 65% for the endothelialized group, versus 16% for the control group (log-rank test, P = .002; Wilcoxon test, P = .003). In phase 2, the 5-year primary patency rate for all in vitro endothelialized infrainguinal reconstructions was 68% (66% for above-the-knee grafts and 76% for below-the-knee grafts). CONCLUSIONS: Nine years of clinical in vitro endothelialization provided strong evidence that autologous endothelial cell lining improves the patency of small-diameter vascular grafts and that a cell culture-dependent procedure can be used in a clinical routine.

In vitro-lined endothelium: initial integrity and ultrastructural events.

BACKGROUND: The early fate of in vitro-endothelialized prosthetic vascular grafts was assessed in the nonhuman primate. METHODS: Each of 17 male chacma baboons received a control and a confluently endothelialized 4 mm polytetrafluoroethylene graft in femoro-femoral positions (8.2 +/- 0.8 cm). All experimental grafts were precoated with fibrinolytically inhibited fibrin glue and lined with cultured autologous endothelial cells (EC) from the external jugular vein. The average time period needed to obtain first-passage mass-cultures sufficient for preconfluent graft endothelialization was 19.8 +/- 5.2 days. Before implantation in vitro-lined grafts were kept in culture for another 16.1 +/- 4.3 days to achieve complete confluence and maturation of the EC cytoskeleton. RESULTS: After 9 days of implantation, endothelial-lined grafts still showed a confluent endothelium that was free of any fibrin deposits. However, the EC density was significantly lower than at implantation (39.7 +/- 7.6 x 10(3) versus 59.9 +/- 8.5 x 10(3) EC/cm2; p < 0.05), and occasional 10-microns-wide intercellular gaps with adherent platelets and leukocytes were visible. Transmission electron microscopy showed leukocytes and cell debris in the underlying fibrin glue. After 4 weeks of implantation, the endothelium of experimental prostheses had regained a high cell density (72.7 +/- 10.5 x 10(3) EC/cm2) with a mature and well-differentiated morphologic appearance. At both observation periods, the surface of control grafts showed a wide range from fibrin deposits to an amorphous protein coverage containing spread platelets. CONCLUSIONS: The endothelium of in vitro-endothelialized vascular prostheses remains confluent after implantation and is nonthrombogenic in spite of a moderate initial cell loss.

Growth properties of cultured human endothelial cells on differently coated artificial heart materials.

The cultivation of autologous endothelial cells on the blood surface of artificial hearts might prevent their detrimental thromboembolic complications. To investigate the growth characteristics of endothelial cells on theoretically suitable biomaterials, we compared three polyurethanes (Pellethane, Biomer, Enka) and three silicone rubbers (Elastosil, 3145 RTV, Medical Adhesive). All synthetic surfaces were precoated with an extracellular matrix (group 1), fibronectin (group 2), or a glutaraldehyde-preserved cellular matrix (group 3). After the seeding of 2.5 x 10(4)/cm2 human endothelial cells into the various surfaces, primary adherence, growth kinetics, and maintenance of monolayer integrity were studied for 13 days. On the three polyurethanes all precoating procedures resulted in endothelial cell proliferation and the formation of persistent monolayers. In contrast, on silicone rubbers a persistent coverage with a confluent endothelium could be achieved only on the glutaraldehyde-preserved cellular matrix. When endothelial cell growth was quantitatively assessed on all precoating substrates, the glutaraldehyde-preserved cellular matrix proved to be far superior on each of the synthetics (p less than 0.001). These results demonstrate the theoretical feasibility of endothelialization of artificial hearts in vitro. Provided such an endothelium can withstand the mechanical forces within an artificial heart, in vitro endothelialization might contribute to a regained attractiveness of the elective long-term implantation of artificial hearts.

Endothelial cell toxicity of solid-organ preservation solutions.

Endothelial cell damage caused by myocardial cardioplegic solutions (Bretschneider HTK and St. Thomas' Hospital No. 2) or renal and hepatic cold storage solutions (modified Collins and University of Wisconsin solution) was assessed in monolayer cultures of adult human venous endothelial cells at 4 degrees to 10 degrees C with phase-contrast microscopy. St. Thomas' Hospital solution caused the cells to contract, resulting in disruption of monolayer integrity and opening of intercellular gaps, and resulted in a 24-hour postexposure survival of 51.0% +/- 2.4%. Bretschneider HTK solution altered cellular morphology less and produced the best postexposure survival (80.2% +/- 2.6%; p less than 0.001). Although morphology was altered the least with University of Wisconsin solution, postexposure survival with this solution, which was similar to that with modified Collins solution, was superior to that with St. Thomas' (p less than 0.01) but inferior to that with Bretschneider HTK (p less than 0.05). The superior protection provided by Bretschneider HTK was due to its additives histidine, tryptophan, and KH-2-oxygluterate (p less than 0.005), and to its low chloride content (p less than 0.005). Furthermore, modifying St. Thomas' solution by decreasing its chloride content improved cell survival to 71.2% +/- 2.3% (p less than 0.001). Normothermic (37 degrees C) exposure to Bretschneider HTK, modified Collins, and University of Wisconsin solution was cytotoxic, whereas normothermic exposure to St. Thomas' cardioplegia was not. In conclusion, the preservation solution that is the least harmful to endothelial cells at hypothermia is Bretschneider HTK cardioplegic solution.

In situ cannulation, microgrid follow-up and low-density plating provide first passage endothelial cell masscultures for in vitro lining.

A rapid and reliable harvest and culture technique was developed to provide a sufficient number of autologous endothelial cells for the confluent in vitro lining of cardiovascular prostheses. Enzymatic endothelial cell detachment was achieved by the in situ application of collagenase to short vessel segments. This harvest technique resulted in a complete lack of contaminating smooth muscle cells in all of 124 cultures from nonhuman primates and 13 cultures from human adults. The use of a microgrid technique enabled the daily in situ quantification of available endothelial cells. To assess ideal plating densities after passage the population doubling time was continuously related to the cell density. Surprisingly, a low plating density of 1.5 X 10(3) endothelial cells/cm2 achieved 43% shorter cell cycles than the usual plating density of 1.0 X 10(4) endothelial cells/cm2. Moreover, low density plating enabled mass cultures after one single cell passage, thereby reducing the cell damaging effect of trypsin. When the growth characteristics of endothelial cells from five anatomically different vessel sites were compared, the external jugular vein--which would be easily accessible and dispensable in each patient--proved to be an excellent source for endothelial cell cultures. By applying in situ administration of collagenase, low density plating and microgrid follow-up to adult human saphenous vein endothelial cells, 14,000,000 first passage endothelial cells--sufficient for the in vitro lining of long vascular prostheses--were obtained 26.2 days after harvest. (95% confidence interval:22.3 to 32.2 days).

Use of fibrin glue as a substrate for in vitro endothelialization of PTFE vascular grafts.

The shear stress resistance of cultured human endothelium was investigated on 6 mm polytetrafluoroethylene vascular grafts. Endothelial cell attachment was promoted by precoating the grafts with fibrin glue, which contained human fibronectin and inhibitors of fibrinolysis (aprotinin and tranexam acid). To evaluate the possible effect of fibrinolysis on cell detachment, seven grafts were lined with adult human saphenous vein endothelial cells (AHSVEC) and 11 with fibrinolytically almost inactive human umbilical vein endothelial cells (HUVEC). Endothelial cell seeding was performed in a microprocessor-controlled rotation device, allowing a low inoculum of 12 X 10(4) endothelial cells/cm2. Grafts were then cultivated for 9 days to enable the maturation of the cytoskeleton, before they were exposed to pulsatile shear stress for 48 hours. A mock circulation simulated the flow patterns and the wall shear forces of the femoral artery. After a 3-hour seeding process, 45% of AHSVEC and 43% of HUVEC were attached to the fibrin matrix, forming a confluent monolayer. After 24 hours of perfusion, a cell loss of 23% in AHSVEC- and of 42% in HUVEC-lined grafts was encountered. In spite of a further cell loss during the following 24 hours of perfusion, the majority of the graft surface was still covered by endothelial cells. Therefore we conclude that fibrin glue is a suitable substrate for the formation of a shear stress-resistant endothelial cell monolayer on polytetrafluoroethylene vascular grafts.

In vitro lining of fibronectin coated PTFE grafts with cryopreserved saphenous vein endothelial cells.

In an attempt to produce instant endothelial cell (EC) monolayers on graft surfaces, cryopreserved cultivated human saphenous vein endothelial cells (HSVEC) were cultivated on reinforced PTFE prostheses. The graft surface was precoated with 40 micrograms/ml human fibronectin (HFN) prior to seeding with 200 x 10(3) EC/cm2. The seeding procedure was performed in a specially designed rotation device. After a cultivation period of 9 days, the seeded endothelial cells on the PTFE prostheses were exposed to shear stresses in a perfusion circuit, containing a bubble oxygenator, a roller pump and a tygon perfusion loop. The applied shear forces were 3 and 6 dyn/cm2, respectively. In control grafts, spontaneous cell detachment occurred from day 11 onwards and only 50% of the graft surface remained endothelialized on day 16. When the grafts were exposed to 3 dyn/cm2 only small cell-free areas less than 1000 micron in diameter were found after 4 hours of perfusion. In contrast, exposure to 6 dyn/cm2 produced discouraging results: as early as 4 hours after the onset of perfusion 50% of the graft surface was cell free. After 16 hours only 20% endothelial cell coverage was seen under the stereo microscope. However, assuming that an ideal precoating substratum can be found, the two stage technique of in vitro endothelialization of vascular grafts with autologous endothelial cells may offer a promising clinical method. Moreover, the fact that our grafts were lined with cryopreserved EC implies the possible prospect of cell banks supplying unlimited numbers of EC for subsequent bypass operations.