Studio comparativo delle proprietà chimico-fisiche di PICC "ex-novo"

In questo studio sono stati analizzati otto cateteri venosi centrali ad inserzione periferica (PICC), provenienti da diversi produttori, aventi medesimo diametro nominale (5 Fr) e tutti monolume. E’ possibile distinguere due classi di PICC sulla base della massima pressione di infusione applicabile: i Power Inejectable (PI) e i non Power Injectable (NPI). Tra quelli inclusi si distinguono quindi cinque NPI e tre PI. Lo scopo di questa tesi è stato quello di caratterizzare la risposta meccanica dei cateteri attraverso opportuni test e misure, al fine di poter confrontare gli otto prodotti e definire dei criteri oggettivi per supportare la fase di scelta dell'operatore sanitario. Per raggiungere questo obiettivo, è stata pianificata una procedura costituita da una serie di analisi, misurazioni e test che evidenziassero peculiarità geometriche, proprietà fisico-chimiche oltre alla risposta meccanica del PICC e del materiale. Si è innanzitutto descritta accuratamente la geometria di ogni PICC: il diametro esterno ed interno, la lunghezza e la curvatura iniziale dovuta al metodo di conservazione dei cateteri negli imballaggi. Tramite rugosimetria si è quindi estratto il profilo microscopico della superficie integrando i dati con immagini di microscopia ottica e elettronica (SEM). La risposta meccanica è stata analizzata tramite test di trazione uniassiale, analisi dinamica al variare della temperatura (DMTA) e kinking test. Le misurazioni sono state effettuate su due campioni per ogni produttore, in modo da verificare al contempo ripetibilità delle misure e affidabilità dei dati. Tramite questa procedura è stato possibile distinguere interessanti scelte adottate dalle aziende. Per quanto riguarda il packaging ogni azienda ha fornito un numero diverso di strumenti, spesso mettendo anche a disposizione materiale che non viene utilizzato, andando quindi a gravare sulla logistica di stoccaggio. Evidenti differenze sono state notate tra i metodi di conservazione del PICC all'interno della confezione, che influisce sulla curvatura iniziale del catetere. I diametri esterni oscillano fra gli 1.64 fino a 1.76 millimetri, alcuni modelli hanno una porzione prossimale conica che raggiunge i 2.3 mm. Non sono state riscontrate significative differenze dal punto di vista della rugosità superficiale e dell'analisi microscopica. Il test di trazione ha evidenziato delle disomogeneità tra campioni nella risposta meccanica, che possono incrementare il rischio clinico se non note a priori al personale ospedaliero. Inoltre ha dato indicazioni sull'utilizzo del medesimo materiale di fabbricazione da parte di tre aziende, peculiarità confermata anche dalle DMTA. Le DMTA hanno inoltre mostrato un ampio range di possibili comportamenti termici tra i vari cateteri. Complessivamente lo studio ha evidenziato la variabilità fra i modelli in commercio anche se appartenenti alla medesima classe (PI o NPI), fornendo degli strumenti alle aziende ospedaliere per la scelta del prodotto PICC

Inverted perovskite solar cells with transparent hole transporting layer based on semiconducting nickel oxide

Perovskite (CH3NH3PbI3) solar cells (PSCs) were produced in the inverted architecture employing transparent nickel oxide (NiO) as hole transporting layer (HTL). The different functional layers of the photoconversion device were solution processed in ambient conditions the HTL of NiO being prepared via sol-gel and successively deposited by spin-coating. The conditions of preparation of the transparent HTL were optimized through the stabilization of the nickel-containing sol with bulky alcohols and strong inorganic acids. The photoactive layer of CH3NH3PbI3 was deposited in air at high relative humidity (ca. 50-60%). The electron selective contact was constituted by spin coated 3H-cyclopropa[1,9] [5,6]fullerene-C60-Ih-3'-butanoic acid 3'-phenyl methyl ester (PCBM) with solution processed 2,9-Dimethyl-4,7-diphenyl-1,10-phenanthroline (bathocuproine, BCP) as interlayer. The deposition of CH3NH3PbI3 in ambient conditions as well as the processing of the BCP interlayer from solution simplified enormously the entire procedure of device fabrication. The largest value of photoconversion efficiency (PCE) we achieved with the inverted architecture photocells was 14 % with an average PCE of 12 %. The solar cells displayed an hysteresis-free behavior with excellent time stability of the maximum power output

Wearable light field optical see-through display to avoid user dependent calibrations: A feasibility study

Wearable augmented reality (AR) is a promising technology for surgical navigation and also for non-medical tasks. Optical see-through displays allow a direct view of the real world augmented with patient related virtual information, which is usually projected on semi-transparent displays placed in front of the eyes. A user-dependent display calibration is required to guarantee a coherent alignment between the virtual information projected on the display and the light rays of the real light field perceived by the user. Integral imaging (II) is a known approach to synthetically generate a light field. A semi-transparent mirror placed at 45° in front of an II display allows obtaining a light field see-through display. In this approach real and virtual information are perceived as coherently aligned independently to the user. In this work we used geometric optics rules to design wearable AR displays, based on II and a semi-transparent mirror, with an optimized visual quality and a tolerated range of movement of the eye in respect to the display. An early implementation demonstrates the feasibility of the proposed solution to implement optical see-through displays that not require user dependent calibrations

WEARABLE VISOR FOR AUGMENTED REALITY

An augmented reality system (10) arranged to superimpose, in front of a user, a virtual light field of a 3D content to the real light field of a surrounding environment. The system (10) provides an augmented reality display (100) comprising a light field display (110) arranged to create a virtual light field of the 3D content, and a beam combiner (130) arranged to deviate the light rays emitted by the virtual light field of the 3D content and project them in front of a user in order to overlap the virtual light field of the 3D content to the real light field of the surrounding environment. Furthermore, the augmented reality display (100) is adapted to be worn by the user on its own head. The augmented reality system (10) also comprises a tracking system (140) arranged to real time monitor position and orientation of a moving reference system S 1 integral to the augmented reality display (100) with respect to a fixed reference system S 2 integral to surrounding environment. The system (10) comprises then a control unit (150) arranged to receive from the tracking system (140) an information about position and orientation of the moving reference system S 1 and to determine the virtual light field of the 3D content coherent with position and orientation of the moving reference system S 1 with respect to the fixed reference system S 2

Thyroid function derangement and childhood obesity: an Italian experience

BACKGROUND: In recent years, there has been an increasing attention to thyroid function in paediatric obese patients. In the present study we aimed 1) to determine the prevalence of abnormally elevated thyroid-stimulating hormone (TSH) levels in Italian obese children and adolescents 2) to investigate whether hyperthyrotropinemia in obese children cardiovascular and metabolic risk factors 3) to verify if TSH elevation is reversible after weight loss. METHODS: We examined 938 obese children and adolescents (450 females). Anthropometric, metabolic and hormonal variables were determined at baseline and, in a subgroup of children with hyperthyrotropinemia, after a six month weight loss program. RESULTS: Hyperthyrotropinemia (TSH ≥4.2 μUI/ml) was diagnosed in 120 patients (12,8%). Body mass index (BMI) z-score (p = 0.02) and free T3 (fT3) levels (p = 0.03) were higher in patients with elevated TSH compared to the group with normal TSH. There were not significant differences in other metabolic parameters between the two groups. A positive correlation between baseline TSH and BMI z-score (p = 0.0045) and between Ft3 and BMI z-score (p = 0.0034) was observed, while there was no correlation between TSH and lipids. Twenty-three patients among those with hyperthyrotropinemia who participated to weight reduction intervention (64 patients), presented substantial weight loss and concomitantly a significant decrease in TSH and in fT3. CONCLUSIONS: These results suggest that: (1) a moderate elevation of TSH concentrations, is frequently found in obese children; (2) in obese children increase of TSH is not associated to metabolic risk factors, (3) hyperthyrotropinemia is reversible after weight loss and these data suggest that it should not be treated

Y2 receptor gene variants reduce the risk of hypertension in obese children and adolescents

OBJECTIVE: To verify whether peptide YY (PYY) and its Y2 receptor (Y2R) gene variants can be associated with obesity or hypertension or both in a cohort of obese children and adolescents. PATIENTS AND METHODS: Two hundred and twenty-nine obese children (105 girls, mean z-score BMI 5.1 ± 2.4; mean age 10.5 ± 2.9 years) and 250 age and sex-matched lean controls (130 women, mean z-score BMI 0.5 ± 1.1; mean age 10.3 ± 2.8) were enrolled in the study. Height, weight, BMI, waist circumference and 24-h systolic and diastolic blood pressure were measured. Night-time, day-time and 24-h systolic and diastolic blood pressures were evaluated by 24 h ambulatory blood pressure measurement, and appropriate standard deviation scores according to sex, age and height were calculated. Molecular screening of the PYY and Y2R genes was performed. RESULTS: No new mutations were found. We observed three previously described polymorphisms: G767C on PYY and T585C and T936C on Y2R. An association study was carried out in obese patients. No associations were found between the PYY genotypes and the studied phenotypes. The Y2R gene variants, T585C and T936C, which are in almost complete linkage disequilibrium, were found to be associated with night-time, day-time and 24-h systolic and diastolic blood pressures. In particular, subject homozygotes for the T allele showed lower systolic and diastolic blood pressure values compared with the other genotypes. Moreover, obese children homozygous for the T585 allele showed a lower risk of developing hypertension than patients carrying the CC and CT genotypes (χ 6.9; df = 1, P = 0.03; odds ratio = 0.5, 95% confidence interval: 0.27-0.88). CONCLUSION: Our results suggest that Y2R gene variants are involved in blood pressure regulation in obese children and adolescents. © 2008 Wolters Kluwer Health | Lippincott Williams & Wilkins

Subclinical hypothyroidism and myocardial function in obese children.

BACKGROUND AND AIMS: Pediatric obesity is an important health problem representing a major public health concern worldwide in the last decades. An isolated elevation of Thyroid Stimulating Hormone (TSH) with normal levels of thyroid hormones is frequently found in obese children. It has been named Isolated Hyperthyreotropinemia or Subclinical Hypothyroidism (SCH) and may be considered a consequence of obesity. Evidence exists that SCH is related to impairment of both systolic and diastolic myocardial function in the adult population. The aim of our study is to establish if obesity-related SCH influences myocardial function in children. METHODS AND RESULTS: We examined 34 obese children and adolescents with SCH and 60 obese children with normal TSH levels who underwent Doppler echocardiographic to evaluate myocardial function. Global systolic function as assessed by Ejection Fraction (EF) was comparable between groups, however Right Ventricle pressure global systolic function and pressure were significantly reduced in SCH group. Mitral annulus peak systolic (MAPSE) excursion lateral and MAPSE septum resulted significantly reduced in SCH group. Tissue Doppler imaging peak systolic motion (TDI-S) was reduced in SCH group. Diastolic function also showed significant modifications in SCH group. CONCLUSION: These results suggest possible involvement of cardiac function in obese children with SCH resulting in both abnormal diastolic function and reduced longitudinal systolic function. This new insight into cardiovascular consequences of obesity-related SCH in children could influence clinical approach to such patients by pediatric endocrinologists

Hepcidin in Obese Children as a Potential Mediator of the Association between Obesity and Iron Deficiency.

Context: Obesity and iron deficiency are two of the most common nutritional disorders worldwide. Several studies found higher rates of iron deficiency in obese than in normal weight children. Hepcidin represents the main inhibitor of intestinal iron absorption and its expression is increased in adipose tissue of obese patients. Leptin is able, in vitro, to raise hepcidin expression. Objectives: Aims of this work were, i) to assess the association between poor iron status and obesity, ii) to investigate if iron homeostasis of obese children may be modulated by serum hepcidin variations and iii) to assess the potential correlation between leptin and serum hepcidin variations. Methods: Iron status and absorption as well as hepcidin, leptin and interleukin-6 levels were studied in 60 obese children and in 50 controls. Results: Obese children showed lower iron and transferrin saturation (both < 0.05) and higher hepcidin levels (p=0.004) compared to controls. A direct correlation between hepcidin and obesity degree (p=0.0015), and inverse correlations between hepcidin and iron (p= 0.04), hepcidin and transferrin saturation (p= 0.005), and hepcidin and iron absorption (p= 0.003) were observed. A correlation between leptin and hepcidin (p= 0.006) has been found. The correlation remained significant when adjusted for body mass index, sex, pubertal stage and interleukin-6 values. Conclusions: We propose that, in obese patients, increased hepcidin production, at least partly leptin mediated, represents the missing link between obesity and disrupted iron metabolism