Comparison of Variational Approaches for the Exactly Solvable 1/r-Hubbard Chain

We study Hartree-Fock, Gutzwiller, Baeriswyl, and combined Gutzwiller-Baeriswyl wave functions for the exactly solvable one-dimensional $1/r$-Hubbard model. We find that none of these variational wave functions is able to correctly reproduce the physics of the metal-to-insulator transition which occurs in the model for half-filled bands when the interaction strength equals the bandwidth. The many-particle problem to calculate the variational ground state energy for the Baeriswyl and combined Gutzwiller-Baeriswyl wave function is exactly solved for the~$1/r$-Hubbard model. The latter wave function becomes exact both for small and large interaction strength, but it incorrectly predicts the metal-to-insulator transition to happen at infinitely strong interactions. We conclude that neither Hartree-Fock nor Jastrow-type wave functions yield reliable predictions on zero temperature phase transitions in low-dimensional, i.e., charge-spin separated systems.Comment: 23 pages + 3 figures available on request; LaTeX under REVTeX 3.

Impact of the estimation equation for GFR on population-based prevalence estimates of kidney dysfunction

Background: Estimating equations are recommended by clinical guidelines as the preferred method for assessment of glomerular filtration rate (GFR). The aim of the study was to compare population-based prevalence estimates of decreased kidney function in Germany defined by an estimated GFR (eGFR

Prävalenz der eingeschränkten Nierenfunktion

Hintergrund: Die Prävalenz von nichtdialysepflichtigen Nierenfunktionsstörungen bei Erwachsenen in Deutschland ist unbekannt. Ihre Kenntnis ist wichtig zur Abschätzung des Versorgungsbedarfs mit Nierenersatztherapien und von ungenutztem Präventionspotenzial. Auch ist die eingeschränkte Nierenfunktion ein wichtiger kardiovaskulärer Risikofaktor. Bisher wurden US-amerikanische Prävalenzschätzungen trotz begrenzter Vergleichbarkeit häufig auf Deutschland übertragen. Methoden: Ausgewertet wurden Daten zur Nierenfunktion aus der bundesweiten „Studie zur Gesundheit Erwachsener in Deutschland 2008–2011 (DEGS1)“ des Robert Koch-Instituts. Hierzu erfolgte eine Schätzung der glomerulären Filtrationsrate (eGFR) aus Serumkreatinin und Cystatin-C (CKD-EPI-Formel) sowie eine semiquantitative Albuminurie-Bestimmung. Zusammenhänge zwischen einer eingeschränkten Nierenfunktion und möglichen Determinanten wurden mittels adjustierter Prävalenzverhältnisse (PR) und 95-%-Konfidenzintervallen (95-%-KI) quantifiziert. Ergebnisse: Etwa 2,3 % (95-%-KI: [1,9; 2,6 ]) der Menschen im Alter von 18–79 Jahren wiesen eine eGFR 80 Jahre sind bundesweit mindestens 2 Millionen Menschen in Deutschland betroffen. Eine Albuminurie ≥ 30 mg/L weisen 11,5 % der Bevölkerung auf. Diabetes mellitus (PR = 2,25, 95-%-KI: [1,59; 3,16]) und arterielle Hypertonie (PR = 3,46, 95-%-KI: [1,95; 6,12]) sind wichtige Determinanten. Schlussfolgerungen: Erstmals liegt mit diesen Daten eine repräsentative Schätzung der Häufigkeit von Nierenfunktionsstörungen in Deutschland vor. Sie zeigt eine starke Altersabhängigkeit, ist jedoch niedriger, als sie auf der Basis US-amerikanischer Daten für Deutschland bislang angenommen wurde

Sustained High Frequencies of Specific CD4 T Cells Restricted to a Single Persistent Virus

Replication of cytomegalovirus (CMV) is largely controlled by the cellular arm of the immune response. In this study the CMV-specific CD4 T-cell response was characterized in a cohort of apparently healthy individuals. In 11% of all individuals, extremely high frequencies, between 10 and 40%, were found. High-level frequencies of CMV-specific CD4 T cells persisted over several months and were not the result of an acute infection. Specific T cells were oligoclonal and were phenotypically and functionally characterized as mature effector cells, with both cytokine-secreting and proliferative potential. These high-level frequencies do not seem to compromise the immune response towards heterologous infections, and no signs of immunopathology were observed. Whereas a large temporary expansion of virus-specific T cells is well known to occur during acute infection, we now show that extremely high frequencies of virus-specific T cells may continuously exist in chronic CMV infection without overtly compromising the remaining protective immunity

Diabetes prevalence and outcomes in hospitalized cardiorenal-syndrome patients with and without hyponatremia

Background!#!Hyponatremia is known to be associated with a worse patient outcome in heart failure. In cardiorenal syndrome (CRS), the prognostic role of concomitant hyponatremia is unclear. We sought to evaluate potential risk factors for hyponatremia in patients with CRS presenting with or without hyponatremia on hospital admission.!##!Methods!#!In a retrospective study, we investigated 262 CRS patients without sepsis admitted to the University Hospital Halle over a course of 4 years. CRS diagnosis was derived from an electronic search of concomitant diagnoses of acute or chronic (NYHA 3-4) heart failure and acute kidney injury (AKIN 1-3) or chronic kidney disease (KDIGO G3-G5!##!Results!#!Two hundred sixty-two CRS patients were included in this study, thereof, 90 CRS patients (34.4%) with hyponatremia (Na < 135 mmol/L). The diabetes prevalence among CRS patients was high (> 65%) and not related to the serum sodium concentration on admission. In comparison to non-hyponatremic CRS patients, the hyponatremic patients had a lower serum osmolality, hypovolemia was more prevalent (41.1% versus 16.3%, p < 0.001). As possible causes of hypovolemia, diarrhea, a higher number of diuretic drug classes and higher diuretic dosages were found. Hyponatremic and non-hyponatremic CRS patients had a comparable need for renal-replacement therapy (36.7% versus 31.4%) during the hospital stay. However, after discharge, relatively more hyponatremic CRS patients on renal replacement therapy switched to a non-dialysis therapy regimen (50.0% versus 22.2%). Hyponatremic CRS patients showed a trend for a higher in-hospital mortality (15.6% versus 7.6%, p = 0.054), but no difference in the one-year mortality (43.3% versus 40.1%, p = 0.692).!##!Conclusions!#!All CRS patients showed a high prevalence of diabetes mellitus and a high one-year mortality. In comparison to non-hyponatremic CRS patients, hyponatremic ones were more likely to have hypovolemia, and had a higher likelihood for temporary renal replacement therapy

Additional file 1: Figure S1. of Impact of the estimation equation for GFR on population-based prevalence estimates of kidney dysfunction

Bland-Altman plots for comparison between Full Age Spectrum creatinine equation (FAScre) and the other equations used to estimate GFR among 7001 adults aged 18–79 in Germany 2008–2011 (DEGS1). MDRD: Modification of Diet in Renal Disease study equation; CKD-EPIcre: Chronic Kidney Disease Epidemiology Collaboration creatinine equation; CKD-EPIcys: Chronic Kidney Disease Epidemiology Collaboration cystatin C equation; CKD-EPIcrecys: Chronic Kidney Disease Epidemiology Collaboration creatinine and cystatin C equation; LM: Lund-Malmö equation; FAScre: Full Age Spectrum creatinine equation. Solid, horizontal lines represent the mean difference between the eGFR. Dashed, horizontal lines represent the limit of agreement between the equations. Solid, vertical lines represent the eGFR cut-off value of a decreased kidney function (60 ml/min/1.73m2). (PDF 422 kb

Subgroups of monocytes predict cardiovascular events in patients with coronary heart disease. The PHAMOS trial (Prospective Halle Monocytes Study)

BACKGROUND: Monocytes can be differentiated by the presence of CD14 and CD16 (CD14++CD16-, classical; CD14++CD16+, intermediate and CD14 + CD16++, non-classical monocytes). Recent studies have reported conflicting results regarding an association between subtypes of monocytes as defined by the expression of these two surface markers in atherosclerosis. METHODS: We investigated subtypes of monocytes in n = 994 patients with angiographically documented coronary artery disease (CAD). We compared total numbers of monocyte subgroups stratified by tertiles with the occurrence of the pre-defined combined endpoint (non-fatal myocardial infarction, cardiovascular death and non-haemorrhagic cerebral insult). Patients were followed up for a minimum of 52 weeks. Classical risk factors of coronary heart disease were included in multivariate analysis. RESULTS:The primary endpoint occurred 134 times at a median time of 34.5 weeks (IR 10.6/59.6). Intermediate (p = 0.813), non-classical (p = 0.725) and the number of total monocytes (p = 0.626) stratified by tertiles showed no significant association with the combined endpoint. However, a higher absolute number of classical monocytes divided in tertiles was associated with incidence of the combined endpoint {T1 = 8.9% vs T2 = 14.2% vs T3 = 16.0% (p = 0.021)}. When comparing the third with the first tertile of Mo1 population, multivariate analysis showed a hazard ratio of 1.646 (CI: 1.005-2.699, p = 0.048). CONCLUSONS: The absolute counts of classical monocytes divided in tertiles are predictive of major adverse cardiac events in patients with CAD. A tremendous shift from classical to intermediate monocytes was also confirmed in patients with CAD. These data highlight the importance of CD14++ monocytes in cardiovascular diseases