Hydrodynamic Trapping of Swimming Bacteria by Convex Walls

Swimming bacteria display a remarkable tendency to move along flat surfaces for prolonged times. This behavior may have a biological importance but can also be exploited by using microfabricated structures to manipulate bacteria. The main physical mechanism behind the surface entrapment of swimming bacteria is, however, still an open question. By studying the swimming motion of Escherichia coli cells near microfabricated pillars of variable size, we show that cell entrapment is also present for convex walls of sufficiently low curvature. Entrapment is, however, markedly reduced below a characteristic radius. Using a simple hydrodynamic model, we predict that trapped cells swim at a finite angle with the wall and a precise relation exists between the swimming angle at a flat wall and the critical radius of curvature for entrapment. Both predictions are quantitatively verified by experimental data. Our results demonstrate that the main mechanism for wall entrapment is hydrodynamic in nature and show the possibility of inhibiting cell adhesion, and thus biofilm formation, using convex features of appropriate curvature

Selfish and Altruistic Bacterial Populations Maximize Fitness Under Stress by Local Segregation

Landscapes in ecology have a profound influence on the adaption and evolution of competing populations for resources. We are interested in how altruistic populations survive in the presence of selfish individuals in a non-stirred, closed and complex nutrient landscape. Well-stirred (landscape-free) but closed environments have a depressing future when selfish individuals arise in a population, a fate known as the tragedy of the Commons. Over-exploitation of a well-stirred communal habitat by selfish individuals which do not follow rules of communal self-regulation ends up in the elimination (extinction) of both the original altruistic inhabitants and the selfish population. In the context of bacterial population, the Commons tragedy that occurs is the consumption of limited resources by the individuals, resulting in metabolic stressing of the bacteria and growth advantages to be gained by defection from a ``social contract" of altruistic cooperation. There is no avoidance of this tragedy and the collapse of an original altruistic wild-type population by an emergent selfish population in a well-stirred but closed environment is inevitable. However, there is a fundamental difference between resource exploitation in a well-stirred homogenous commons and in a heterogenous landscape of nutrients which is not stirred. We show here using a non-stirred nanofabricated habitat landscape that altruists and selfish bacteria can in fact coexist, that they can maintain phenotype diversity and avoid the tragedy of the Commons. This emergent spatial segregation of competing populations under stress greatly changes, we believe, our perception of the true sophistication of bacterial response to stress and competition, and has broad implications for the adaptive strategies of higher organisms under stress in complex environments

Body mass index before kidney transplantation — principal risk factor for NODAT

Purpose. Pretransplant obesity is a well-known risk factor for post-transplant outcomes such as patient and graft survival, delayed graft function, rejection, and wound complications. According to the recommendations of the European Renal Best Practice, patients who have body mass index (BMI) value of more than 30 kg/m2 before kidney transplantation should reduce their weight. Materials and methods. In the group of 297 patients who had undergone primary kidney transplantation from post-mortem donors, we found that assessed the impact of BMI on the development of new onset diabetes after transplantation (NODAT). Additionally, relationships between immunosuppression, weight gain and BMI in patients after kidney transplantation were also analysed. We measured the value of the patients’ BMI and weight before kidney transplantation, 12 months after kidney transplantation, and 5 years after kidney transplantation. The group contained only those patients who, at the time of the kidney transplantation, did not suffer from diabetes mellitus. According to the development of NODAT in the monitored period, the group of patients was divided into the control group and NODAT group. We detected analysed the data on the type of immunosuppression (tacrolimus, cyclosporine A, mTOR inhibitor) and the average levels in the monitored period and identified whether BMI or increased weight 12 months and 5 years after kidney transplantation is related to the level (or dose) of the used immunosuppression. Results. In our group, the patients who developed NODAT in the post-transplant period were significantly older in the 12-month analysis (p < 0.0001) and also in the 5-year analysis (p = 0.0001); had higher BMI at the time of transplantation (p = 0.0003) and higher BMI 12 months after kidney transplantation (p = 0.0004) and a significantly higher weight gain 12 months after kidney transplantation (p = 0.0469). We discovered that neither the level of immunosuppression nor the dose of prednisone had any effect on the increase in BMI or weight gain during the monitored period. Conclusion. The patients in the waiting list, who have any risk factors for the development of diabetes mellitus, should be informed how to eliminate these risk factors (weight control, diet, physical exercises, etc.). In addition to the above, all candidates for kidney transplantation are recommended to stop smoking, to control blood pressure, and perform a lipidogram

Czy palenie tytoniu jest czynnikiem ryzyka zespołu metabolicznego?

Background. We define metabolic syndrome as a non-random collective incidence of glucose metabolism disorders related to insulin resistance, central obesity, dyslipidemia, arterial hypertension and other factors which contribute to increased risk of ischemic heart disease and diabetes mellitus type 2. Smoking is one of the most significant risk factors for ischemic heart disease.Objectives and methods. A prospective analysis of 125 patients (75 men and 50 women) with the averageage of 57.3 years. A subset of smokers was composed of 59 patients; the average number of cigarettes smoked per day was 18 pieces. A subset of non-smokers was composed of 66 patients. We examined the presence of metabolic syndrome components according to the International Diabetic Federation criteria for the European population throughout the whole set of patients.Results. Percentually higher incidence of metabolic syndrome occurred in the group of non-smokers. The incidence of metabolic syndrome in the group of smokers was significantly influenced by their age. Arterial hypertension and impaired fasting glucose were the most frequent components of metabolic syndrome in the subset of smokers with metabolic syndrome. In the subset of non-smokers with metabolic syndrome arterial hypertension was the most frequently found component.Conclusion. The results of the research did not show statistically significantly increased or decreased incidence of metabolic syndrome in case of smokers. We did not find any relation between the number of cigarettes smoked per day and metabolic syndrome development.Wstęp. Zespół metaboliczny określa się jako współwystępowanie zaburzeń metabolizmu węglowodanów związanych z insulinoopornością, otyłością brzuszną, dyslipidemią, nadciśnieniem tętniczym i innymi czynnikami przyczyniającymi się do zwiększonego ryzyka choroby niedokrwiennej serca i cukrzycy typu 2. Jednym z najważniejszych czynników ryzyka choroby niedokrwiennej serca jest palenie tytoniu.Cel badania i metody. Przeprowadzono prospektywną analizę 125 chorych (75 mężczyzn i 50 kobiet), których średnia wieku wynosiła 57,3 roku. Podgrupa osób palących obejmowała 59 chorych; średnia liczba wypalanych dziennie papierosów wynosiła 18 sztuk. Podgrupa osób niepalących składała się z 66 chorych. Autorzy zbadali częstość występowania zespołu metabolicznego rozpoznawanego zgodnie z kryteriami International Diabetic Federation dla populacji europejskiej w całej badanej grupie pacjentów.Wyniki. Większy odsetek osób z zespołem metabolicznym stwierdzono w grupie osób niepalących. Na częstość występowania zespołu metabolicznego w grupie osób palących istotnie wpływał wiek chorych. Nadciśnienie tętnicze i nieprawidłowa glikemia na czczo były najczęstszymi elementami składowymi zespołu metabolicznego w podgrupie osób palących z zespołem metabolicznym. W podgrupie osób niepalących z zespołem metabolicznym najczęściej stwierdzanym elementem zespołu metabolicznego było nadciśnienie tętnicze.Wnioski. Wyniki badania nie wykazały statystycznie istotnego zwiększenia ani zmniejszenia częstości występowania zespołu metabolicznego w przypadku osób palących. Autorzy nie stwierdzili żadnych zależności między liczbą wypalanych dziennie papierosów a rozwojem zespołu metabolicznego.

Body mass index before kidney transplantation — principal risk factor for NODAT

Cel. Otyłość przed przeszczepieniem nerki jest znanym czynnikiem ryzyka wpływającym na wyniki leczenia, w tym przeżycie pacjenta i przeszczepu, opóźnienie w podjęciu czynności przez przeszczep, odrzucenie przeszczepu i powikłania związane z raną. Zgodnie z zaleceniami European Renal Best Practice (ERBP) chorzy, u których wskaźnik masy ciała (BMI) przed przeszczepieniem nerki wynosi ponad 30 kg/m2, powinni zmniejszyć masę ciała. Materiały i metody. W grupie 297 chorych poddanych pierwotnemu przeszczepieniu nerki od zmarłego dawcy oceniano wpływ BMI na rozwój cukrzycy potransplantacyjnej (NODAT) oraz zależności między leczeniem immunosupresyjnym a przyrostem masy ciała i wartością wskaźnika BMI po transplantacji. Wskaźnik BMI i masę ciała uczestników badania zmierzono przed transplantacją oraz 12 miesięcy i 5 lat po przeszczepieniu nerki. Analizowana grupa obejmowała tylko osoby, które w czasie transplantacji nerki nie chorowały na cukrzycę. Uczestników badania podzielono na dwie grupy w zależności od tego, czy w okresie obserwacji rozwinęła się u nich cukrzyca potransplantacyjna: osoby, u których nie stwierdzono NODAT, utworzyły grupę kontrolną, a pozostali — grupę NODAT. Zebrano dane dotyczące stosowanych leków immunosupresyjnych (takrolimus, cyklosporyna A, inhibitor mTOR, prednizon) oraz średnich stężeń tych leków i sprawdzono, czy wartość BMI lub przyrost masy ciała 12 miesięcy i 5 lat po przeszczepieniu nerki ma związek ze na stężeniem (lub dawką) stosowanych leków immunosupresyjnych. Wyniki. W analizowanej grupie chorzy, u których rozwinęła się NODAT, byli istotnie starsi, dotyczyło to zarówno danych obejmujących okres 12 miesięcy (p < 0,0001), jak i 5 lat (p = 0,0001) po przeszczepieniu nerki, mieli wyższy BMI w czasie transplantacji nerki (p = 0,0003) i po 12 miesiącach od zabiegu (p = 0,0004) oraz istotnie większy przyrost masy ciała 12 miesięcy po transplantacji (p = 0,0469). Stwierdzono, że ani stężenie leków immunosupresyjnych, ani dawka prednizonu nie miały wpływu na zwiększenie wskaźnika BMI ani przyrost masy ciała w okresie obserwacji. Wnioski. Chorych znajdujących się na liście oczekujących na przeszczep nerki, u których występują jakiekolwiek czynniki ryzyka cukrzycy, należy poinformować o metodach wyeliminowania tych czynników (kontrola masy ciała, dieta, aktywność fizyczna itp.). Ponadto standardowe zalecenia w tej grupie chorych obejmują zaprzestanie palenia tytoniu, kontrolę ciśnienia tętniczego i monitorowanie stężeń lipidów.Purpose. Pretransplant obesity is a well-known risk factor for post-transplant outcomes such as patient and graft survival, delayed graft function, rejection, and wound complications. According to the recommendations of the European Renal Best Practice, patients who have body mass index (BMI) value of more than 30 kg/m2 before kidney transplantation should reduce their weight. Materials and methods. In the group of 297 patients who had undergone primary kidney transplantation from post-mortem donors, we found that assessed the impact of BMI on the development of new onset diabetes after transplantation (NODAT). Additionally, relationships between immunosuppression, weight gain and BMI in patients after kidney transplantation were also analysed. We measured the value of the patients’ BMI and weight before kidney transplantation, 12 months after kidney transplantation, and 5 years after kidney transplantation. The group contained only those patients who, at the time of the kidney transplantation, did not suffer from diabetes mellitus. According to the development of NODAT in the monitored period, the group of patients was divided into the control group and NODAT group. We detected analysed the data on the type of immunosuppression (tacrolimus, cyclosporine A, mTOR inhibitor) and the average levels in the monitored period and identified whether BMI or increased weight 12 months and 5 years after kidney transplantation is related to the level (or dose) of the used immunosuppression. Results. In our group, the patients who developed NODAT in the post-transplant period were significantly older in the 12-month analysis (p < 0.0001) and also in the 5-year analysis (p = 0.0001); had higher BMI at the time of transplantation (p = 0.0003) and higher BMI 12 months after kidney transplantation (p = 0.0004) and a significantly higher weight gain 12 months after kidney transplantation (p = 0.0469). We discovered that neither the level of immunosuppression nor the dose of prednisone had any effect on the increase in BMI or weight gain during the monitored period. Conclusion. The patients in the waiting list, who have any risk factors for the development of diabetes mellitus, should be informed how to eliminate these risk factors (weight control, diet, physical exercises, etc.). In addition to the above, all candidates for kidney transplantation are recommended to stop smoking, to control blood pressure, and perform a lipidogram.

The Effects of Chemical Interactions and Culture History on the Colonization of Structured Habitats by Competing Bacterial Populations: Data Set

We explored the colonization of a patchy ecosystem by two neutrally labeled, but otherwise isogenic, strains of Escherichia coli. One-dimensional arrays of habitat patches linked by connectors were inoculated at opposite ends by two fluorescently-labeled strains, and the colonization was studied by time-lapse microscopy. We focussed on the degree of reproducibility of the resulting colonization patterns and on the interactions between the two populations during the colonization process

Insulin Pump Therapy – Influence on Body Fat Redistribution, Skeletal Muscle Mass and Ghrelin, Leptin Changes in T1D Patients

Background: To report changes in body composition and biochemical parameters in patients with type 1 diabetes mellitus (T1D) after switching from multiple daily injection (MDI) to continuous subcutaneous insulin infusion (CSII). Methods: 31 patients switched over from MDI to CSII. Body composition, biochemical parameters, glycaemic variability (GV) and level of physical activity were evaluated before and 6 months on CSII. Results: In both sexes, we found an increase in skeletal muscle mass (SMM), (p = 0.008; 0.008). In men, there was mainly a decrease in visceral fat area (VFA), (p = 0.028) and in women there was decrease of total body fat (TBF), (p = 0.020) and non-significant decrease of VFA (p = 0.098). SMM inversely correlated with VFA in men (p = –0.001) and with TBF in women (p = –0.005 ). GV was decreased generally and correlated inversely with TBF in men only (p = –0.026). Physical activity was increased and correlated inversely with VFA in men (p = –0.002) and in women (p = –0.006). Conclusions: Using CSII in T1D leads to a significant increase of SMM in both sexes to a decrease of VFA in men and to a non-significant decrease of VFA in women. Changes in adipose tissue and SMM were also related to increased physical activity and to decreased GV

Variance in Landscape Connectivity Shifts Microbial Population Scaling

Understanding mechanisms shaping distributions and interactions of soil microbes is essential for determining their impact on large scale ecosystem services, such as carbon sequestration, climate regulation, waste decomposition, and nutrient cycling. As the functional unit of soil ecosystems, we focus our attention on the spatial structure of soil macroaggregates. Emulating this complex physico-chemical environment as a patchy habitat landscape we investigate on-chip the effect of changing the connectivity features of this landscape as Escherichia coli forms a metapopulation. We analyze the distributions of E. coli occupancy using Taylor's law, an empirical law in ecology which asserts that the fluctuations in populations is a power law function of the mean. We provide experimental evidence that bacterial metapopulations in patchy habitat landscapes on microchips follow this law. Furthermore, we find that increased variance of patch-corridor connectivity leads to a qualitative transition in the fluctuation scaling. We discuss these results in the context of the spatial ecology of microbes in soil