Arterial stiffness, endothelial and cognitive function in subjects with type 2 diabetes in accordance with absence or presence of diabetic foot syndrome

Abstract Background Endothelial dysfunction is an early marker of cardiovascular disease so endothelial and arterial stiffness indexes are good indicators of vascular health. We aimed to assess whether the presence of diabetic foot is associated with arterial stiffness and endothelial function impairment. Methods We studied 50 subjects with type 2 diabetes mellitus and diabetic foot syndrome (DFS) compared to 50 diabetic subjects without diabetic foot, and 53 patients without diabetes mellitus, by means of the mini mental state examination (MMSE) administered to evaluate cognitive performance. Carotid-femoral pulse wave velocity (PWV) and augmentation index (Aix) were also evaluated by Applanation tonometry (SphygmoCor version 7.1), and the RH-PAT data were digitally analyzed online by Endo-PAT2000 using reactive hyperemia index (RHI) values. Results In comparison to diabetic subjects without diabetic foot the subjects with diabetic foot had higher mean values of PWV, lower mean values of RHI, and lower mean MMSE. At multinomial logistic regression PWV and RHI were significantly associated with diabetic foot presence, whereas ROC curve analysis had good sensitivity and specificity in arterial PWV and RHI for diabetic foot presence. Conclusions Pulse wave velocity and augmentation index, mean RHI values, and mean MMSE were effective indicators of diabetic foot. Future research could address these issues by means of longitudinal studies to evaluate cardiovascular event incidence in relation to arterial stiffness, endothelial and cognitive markers

KPC-3 Klebsiella pneumoniae ST258 clone infection in postoperative abdominal surgery patients in an intensive care setting: analysis of a case series of 30 patients

Objective: We studied the clinical course, Intensive Care Unit (ICU) and hospital outcomes of 30 postoperative abdominal surgery patients who showed severe infections caused by Klebsiella pneumoniae Sequence Type 258 producing K. pneumoniae carbapenemase 3 (KPC-Kp). Methods: Patients with at least two positive blood cultures for KPC-Kp after admission to the ICU were recruited for a 12-month period and treated with a combination regimen of colistin plus tigecycline. They were started on a high-dose (initial dose of 200 mg then 100 q12) of tigecycline combined with colistin, taking into account intra-abdominal abscess severity and MCIs for tigecycline. Results: The average age of the patients was 56.6 ± 15 (male = 16, female = 14), average APACHE score on admission was 22.72. Twenty out of 30 patients (66%) came from the surgical emergency unit. Patients showed KPC-Kp postoperative infection as follows: intra-abdominal abscess in 15 patients (50%), anastomotic leakage in 8 (24%), surgical site infection (SSI) in 4 (12%) and peritonitis in 3 (10%). Overall crude mortality rate in the ICU due to infection was 40% (12 out of 30 patients). Twelve out of 30 patients (40%) were started on a combination treatment of high-dose tigecycline and intravenous colistin; five of them showed tigecycline MICs of 0.8 - 1. Mortality was significantly associated with a greater number of surgical procedures, previous ICU admission (<0.0005), APACHE II ( p=0.018)and SOFA score (p<0.0005) and VAP (0.013). Treatment with high doses of tigecycline obtained a favourable outcome in patients with intraabdominal abscess. Discussion: Critically-ill surgical patients with KPC-Kp infections have to be treated in a timely manner, taking into account the severity of post-operative complications such as intra-abdominal abscess and anastomotic leakage. In these cases, early suspicion and detection are essential to reducing infection-related morbidity and mortality. Finally, studies evaluating antibiotic combination therapy and well-controlled clinical trials are needed to define the optimal treatment of infections caused by KPC-Kp and, more generally, carbapenem-resistant bacteria

Colorectal Cancer Stage at Diagnosis Before vs During the COVID-19 Pandemic in Italy

IMPORTANCE Delays in screening programs and the reluctance of patients to seek medical attention because of the outbreak of SARS-CoV-2 could be associated with the risk of more advanced colorectal cancers at diagnosis. OBJECTIVE To evaluate whether the SARS-CoV-2 pandemic was associated with more advanced oncologic stage and change in clinical presentation for patients with colorectal cancer. DESIGN, SETTING, AND PARTICIPANTS This retrospective, multicenter cohort study included all 17 938 adult patients who underwent surgery for colorectal cancer from March 1, 2020, to December 31, 2021 (pandemic period), and from January 1, 2018, to February 29, 2020 (prepandemic period), in 81 participating centers in Italy, including tertiary centers and community hospitals. Follow-up was 30 days from surgery. EXPOSURES Any type of surgical procedure for colorectal cancer, including explorative surgery, palliative procedures, and atypical or segmental resections. MAIN OUTCOMES AND MEASURES The primary outcome was advanced stage of colorectal cancer at diagnosis. Secondary outcomes were distant metastasis, T4 stage, aggressive biology (defined as cancer with at least 1 of the following characteristics: signet ring cells, mucinous tumor, budding, lymphovascular invasion, perineural invasion, and lymphangitis), stenotic lesion, emergency surgery, and palliative surgery. The independent association between the pandemic period and the outcomes was assessed using multivariate random-effects logistic regression, with hospital as the cluster variable. RESULTS A total of 17 938 patients (10 007 men [55.8%]; mean [SD] age, 70.6 [12.2] years) underwent surgery for colorectal cancer: 7796 (43.5%) during the pandemic period and 10 142 (56.5%) during the prepandemic period. Logistic regression indicated that the pandemic period was significantly associated with an increased rate of advanced-stage colorectal cancer (odds ratio [OR], 1.07; 95%CI, 1.01-1.13; P = .03), aggressive biology (OR, 1.32; 95%CI, 1.15-1.53; P &lt; .001), and stenotic lesions (OR, 1.15; 95%CI, 1.01-1.31; P = .03). CONCLUSIONS AND RELEVANCE This cohort study suggests a significant association between the SARS-CoV-2 pandemic and the risk of a more advanced oncologic stage at diagnosis among patients undergoing surgery for colorectal cancer and might indicate a potential reduction of survival for these patients

Nanodispositivi elettronici con eterostrutture AlGaN/GaN

Nell'ambito della ricerca scientifica sui dispositivi elettronici a semiconduttore, il Nitruro di Gallio (GaN) è stato oggetto negli ultimi dieci anni di un interesse sempre crescente, grazie alle straordinarie caratteristiche fisiche del gas bidimensionale (2DEG, Two-Dimensional Electron Gas) ottenibile nelle eterostrutture composte dal GaN e dal Nitruro di Gallio e Alluminio (AlGaN). Le eterostrutture AlGaN/GaN sono state utilizzate nella realizzazione di transistor a elevata mobilità (HEMT, High Electron Mobility Transistor). Il processo di fabbricazione sviluppato ha portato alla realizzazione di elettrodi di gate di elevata qualità, ottenuti mediante litografia a fascio elettronico; i GaN-HEMT realizzati hanno manifestato ottime prestazioni in termini di comportamento dinamico e di breakdown. A partire dai 2DEG presenti nelle eterostutture AlGaN/GaN sono stati realizzati nanodispositivi elettronici, utilizzando la tecnica split-gate. Sono stati ottenuti dispositivi tipo Quantum Point Contact con geometria unidimensionale, e forma degli elettrodi sia simmetrica che asimmetrica. La caratterizzazione elettrica a temperature criogeniche delle nanostrutture con elettrodi simmetrici ha mostrato un andamento della conduttanza 1D simile a quello previsto per la quantizzazione regolare in un sistema con degenerazione di spin, con la soppressione di alcuni plateau. La soppressione dei plateau è attribuibile all'apertura di un canale parallelo nella costrizione, dovuto alla probabile occupazione della seconda sottobanda 2D da parte del 2DEG, favorita dall'elevato valore dell'energia di Fermi del sistema. Nella conduttanza dei sistemi 1D ottenuti da split-gates asimmetrici sono emerse diverse strutture anomale nella conduttanza, la più evidente delle quali a 0.5*(2e2/h). I plateau anomali nella conduttanza, accompagnati da risonanze, sono probabilmente da attribuire ad effetti di interferenza legati alla geometria del potenziale

Terahertz current oscillations in a gated two-dimensional electron gas with antenna integrated at the channel ends

We studied terahertz current oscillations induced by a frequency-tunable radiation source in a AlGaAs/InGaAs/AlGaAs heterostructure field effect transistor channel. A planar antenna was integrated on-chip, and a substrate lens was used for broadband coupling of free-space radiation at 0.18-0.72 THz to the channel ends. Through spectral analysis of the detection signal, we identified two different mixing mechanisms: one related to channel current oscillations and the other to modulation of the gate-to-channel potential. Depending on gate bias and radiation frequency, the two mechanisms either compete or cooperate, leading to responsivity up to 300 V/W and noise equivalent power of 1 nW/Hz(0.5) (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4717464

Responsivity at 0.27 THz of a heterostructure field effect transistor detector in a quasi-optical package

We have fabricated AlGaAs/InGaAs/AlGaAs heterostructure field effect transistors (HFET) with integrated on-chip antennas and we have measured their optical responsivity when mounted in a in-house developed quasi-optical package with a silicon substrate lens © 2013 IEEE

Terahertz Resonators Based on YBa₂Cu₃O₇ High-<i>T</i>_c Superconductor

Superconducting split-ring resonator arrays allow to overcome two main limitations affecting metallic metamaterial resonating in the terahertz (THz) range: ohmic losses and tunability of their optical response. In this work, we design and experimentally realize direct and complementary square arrays of superconducting YBa2Cu3O7 (YBCO) split-ring resonators working in the THz spectral range. The main purpose of this paper is to show how the metamaterial resonances can be tuned by temperature (T) when crossing the superconducting transition temperature Tc of YBCO. The tuning property can be quantified by describing the THz transmittance of the patterned YBCO films vs. T through a model of coupled resonators. This model allows us to estimate the THz resonances of split-ring arrays and their interaction, showing how the kinetic inductance Lk in the superconducting state is the main parameter affecting the metamaterial properties