1,721,737 research outputs found
Ricerca e caratterizzazione di micro e nano plastiche in alimenti, fluidi biologici e ambienti lavorativi del settore plastico
Full text linkUno degli aspetti più insidiosi dell’inquinamento causato dalla plastica è dovuto alla presenza di micro e nano plastiche nell’ambiente, si tratta di un problema che è stato
investigato solo di recente e sul quale non vi è ancora una letteratura scientifica consolidata. L’attenzione della comunità scientifica e dell’opinione pubblica è in crescita su questi nuovi inquinanti a seguito della scoperta di microplastiche nell’ organismo umano e negli alimenti, ciò sta lentamente portando i legislatori di vari paesi e dell’Unione Europea ad intervenire sul problema. Questo intervento sta riguardando attualmente la limitazione dell’immissione di plastiche e microplastiche nell’ambiente, ma in futuro potrebbe concretizzarsi ad esempio nell’imposizione di limiti di legge alla contaminazione di microplastiche degli alimenti e nei luoghi di lavoro, di conseguenza vi è la necessità di disporre di un metodo di analisi delle microplastiche per poter valutare l’ampiezza del problema. Lo scopo di questa tesi è di approfondire la conoscenza della contaminazione da microplastiche tramite lo studio, la valutazione e l’impiego di una serie di metodi per l’analisi delle microplastiche in diverse matrici. Questa tesi si concentra sull'analisi delle microplastiche nel sale, un ingrediente presente nella stragrande maggioranza degli alimenti, sul quale vi sono pochi studi, nonostante provenga in gran parte dall'evaporazione dell'acqua di mare dove è nota da tempo la presenza di importanti concentrazioni di microplastiche. Un'altra fonte di assunzione delle microplastiche analizzata da questo studio è l'esposizione professionale alle polveri di microplastiche, sulla quale non vi sono ancora importanti studi; infine è stato studiato un protocollo per l'analisi dei traccianti organici delle microplastiche nei liquidi biologici, nello specifico gli esteri dell'acido ftalico, la cui presenza nelle urine è correlata all'esposizione
dell'organismo alle microplastiche. Questo dottorato di ricerca ha compreso delle attività che sono state svolte presso il dipartimento di ingegneria dell'Università di Aalborg,
Danimarca, grazie alla collaborazione con il prof. Vollertsen tramite un progetto di mobilità congiunta coordinato dalla prof.ssa Buiarelli; altre attività sono state svolte presso il
dipartimento di agricoltura, ambiente ed alimenti dell’Università degli Studi del Molise grazie alla collaborazione del prof. Avino.The presence of micro and nano plastics in the environment is one of the most insidious aspects of plastic pollution, the scientifical investigation of this environmental problem
has started recently and there isn’t a consolidated scientific literature about this important issue. The concern of the scientific community and public opinion on these new pollutants grows by the discovery of microplastics in the human body and in food. The concern about microplastics is slowly leading the United States of America, the
European Union and various other countries to act on the problem. These actions against microplastics pollution are currently concerning limitation of plastics release
into the environment and a ban on microplastic additives in personal care products. The concern of microplastics could lead to imposition of legal limits on microplastics
contamination of foods and workplaces, so we need a method for microplastics analysis that quantifies the microplastic contamination. The purpose of this thesis is to increase
the knowledge of microplastic contamination using of a series of methods for the microplastics analysis in environments and products. This thesis focuses on microplastics analysis in table salt, an ingredient widely used in foods. There are few scientifical articles about microplastics in table salt despite it mostly comes from the evaporation of sea water where there is an important presence of microplastics. The worker’s exposure to microplastic dusts, on which there are still few studies, is another source of microplastics intake that is analyzed by this thesis. The last part of this thesis is about the human body exposure by microplastics. It concerns the development of an analysis method for phthalic acid esters, who are plastic additives, in urine because the concentration of phthalic acid esters in urine is related to human body exposure by microplastics. The analysis of microplastics in table salt has happened with the dissolution of the table salt samples in water, followed by the filtration of the saline solutions, in the end the filters are observed with an optical microscope and certain fibers on the filter are analyzed with the Raman spectroscopy. The other method used for the table salt analysis has required a more complex pretreatment o the sample followed by an imaging analysis micro-FT-IR and an imaging micro-Raman. The microplastics in the workplaces dust are sampled with a filter linked with an air pump, then the filters are observed with an optical microscope and certain fibers on the filter are analyzed with the Raman spectroscopy. The development of the method for phthalic acid esters analysis has brought to a solid phase extraction (SPE) of the analytes from the urine simulating solution followed by an analysis with gas chromatography (GC-FID). The results of this three-years work shows that the analysis of microplastics is complex for the great diversity of the various kind of microplastics, by dimensions and chemical properties. For this reason, the method for analyze the microplastics should use various kind of scientifical instruments, whose results are complementary to determinate the true degree of microplastics contamination
Rationale, pros and cons of GFR estimation: the Cockcroft-Gault and MDRD equationsGIORNALE ITALIANO DI NEFROLOGIA
No full textCurrent guidelines suggest to evaluate kidney function by estimates of the
glomerular filtration rate (GFR) calculated using the Cockcroft-Gault equation
or the simplified equation of the Modification of Diet in Renal Disease (MDRD)
study. Cockcroft and Gault developed a method to predict an individual’s creatinine
clearance without urinary data but on the basis of average creatinine
clearance values corrected for age and body weight. The equation needs
information about gender, age, weight, and serum creatinine. The precision
of the equation is biased by overweight because the equation is based on the
assumption that creatinine clearance linearly reflects body weight. The MDRD
equation derives from a multiple regression used to analyze the relation of
GFR measurements by a radioisotope technique over serum creatinine after data linearization by logarithm transformation and with control for gender, age, ethnicity and other variables. The equation has not been validated for GFR >60 mL/min x 1.73 m2 because the study did not include healthy persons. The two equations often give conflicting estimates of GFR. Nephrologists have to understand the rationale of the two equations for the correct interpretation of these discrepancies. (G Ital Nefrol 2009; 26: 310-7
Molecular delivery of cytotoxic agents via integrin activation
Full text linkIntegrins are cell adhesion receptors overexpressed in tumor cells. A direct inhibition of integrins was investigated, but the best inhibitors performed poorly in clinical trials. A gained attention towards these receptors arouse because they could be target for a selective transport of cytotoxic agents. Several active-targeting systems have been developed to use integrins as a selective cell entrance for some antitumor agents. The aim of this review paper is to report on the most recent results on covalent conjugates between integrin ligands and antitumor drugs. Cytotoxic drugs thus conjugated through specific linker to integrin ligands, mainly RGD peptides, demonstrated that the covalent conjugates were more selective against tumor cells and hopefully with fewer side effects than the free drugs
[Treatment of autosomal dominant polycystic kidney disease (ADPKD) - Tolvaptan].
No full textThe European Medicines Agency approved tolvaptan to slow cyst growth and renal failure progression in adults with ADPKD, glomerular filtration 60 mL/min x 1.73 m2 and rapidly progressive disease. In a multicenter 3-year study, conducted on 1,445 patients with non-genotyped ADPKD, ages 18-50 years, predicted creatinine clearance 60 mL/min and kidney total volume 750 mL, tolvaptan slowed kidney failure progression (-23%-46% for different objectives) and reduced kidney volume increase and pain without effects on hypertension and albuminuria.Tolvaptan induced reversible idiosyncratic hepatopathy in 4% of patients (1% in placebo). Tolvaptan antagonizes ADH effects, reduces cyclic-AMP generation in distal nephron, and induces water diuresis. It has high protein-binding and 8-hour half-life. Dosage is 60-120 mg/day in two different doses (for instance 45/15 or 60/30 mg). Treatment starts using lower dose and continues with cautious up-titolation. Data are insufficient for severe hepatopathy or nephropathy. There is no antidote against overdose. Dialysis should not remove tolvaptan. Aquaretic effects require high fluid intake to prevent dehydration. Treatment should be reduced or suspended in case of inadequate fluid intake or dehydration. Weight, natremia and plasma osmolality can inform on dehydration risks. Efficacy is not yet investigated on end-stage renal disease, non-renal ADPKD-related disorders, and mortality
Evaluation of glomerular filtration rate and of albuminuria/proteinuria.
No full textKidney function should be evaluated by procedures
including the calculation of glomerular filtration rate
(GFR) estimates and the assessment of albuminuria or
proteinuria as creatinine-normalized urinary ratios for
albumin or total protein. GFR estimates are an approximation
of true GFR, which circumvent the limitations
of serum creatinine and creatinine clearance without
increasing costs and time of diagnostic work-up. Estimates
by Cockcroft-Gault equation tend to be higher
than true GFR and estimates by other equations, because
this equation predicts creatinine clearance,
hence true GFR plus creatinine excretion via tubular
secretion. The inclusion of a weight coefficient in the
equation causes a GFR overestimation in the presence
of large adiposity or edema. Estimates by equations of
the Modification of Diet in Renal Disease (MDRD) study
can be unreliable for high-normal GFR because that
study did not enroll individuals without kidney disease.
The Chronic Kidney Disease Epidemiology Collaboration
(CKD-EPI) group has reported a new equation to
overcome this limitation. GFR estimates can be biased
by interassay creatinine differences or unusual levels
of creatinine generation (muscle mass) or of renal tubular
creatinine secretion. The urinary ratio of albumin
(or total protein) to creatinine is measurable in untimed
spot urine and reflects the urinary excretion rate
of albumin (or total protein). Low muscle mass could
imply borderline elevation in the ratio merely because
of low urinary creatinine. Vice versa, high muscle mass
could imply normal ratios even in the presence of high
urinary albumin, because of high urinary creatinine
due to high creatinine generation
THE IMPACT OF SALT RESTRICTION ON THE EFFECTIVENESS OF ANTIHYPERTENSIVE THERAPY
No full text“... if too much salt is added in foods the pulse hardens”. This statement appearing in the Yellow Emperor Textbook of Internal Medicine (c2500 BC) indicates that a causal relation between sodium intake and blood pressure was already taken for granted in Ancient China some 4,500 years ago. Therefore our contemporary understanding that healthy diets are basically low in sodium has historical roots which finally attracted the
interest of scientists of the twentieth century who provided controlled evidence that Kempner’s rice diets reduced blood pressure because of their low sodium content. With that demonstration sodium restriction was identified as an effective treatment for hypertension to be controlled by continuous monitoring of urinary sodium over time. The list of papers on blood pressure profiles in people from low and high salt culture, going
from populations with virtually no sodium intake to population with excessive sodium intake has widened the cultural horizons. This allowed Page to suggest in 1980 that “when all individuals of a population ingest small amounts of sodium, blood pressure does not increase with age and hypertension is virtually absent. When all members of the populations are ingesting large amount of sodium a high percentage develop hypertension. Between these extremes the relationship between blood pressure and sodium intake is difficult to perceive because of wide variation in genetic susceptibility and other type of “noise” introduced by other variables. The relationship, nevertheless, probably is present in all populations. A moderate reduction in sodium intake to 70 mmol/day would do no harm, and might do a great deal of good”. Further advancement
was achieved by learning that a small addition of sodium to the milk in feeding newborn babies significantly increased their blood pressure within short time. Finally clinical trials in the last decade have shown a reduction in blood pressure following a restriction in sodium intake in non-hypertensive persons ingesting typical American meals and have fixed at 65 mmol per day the ideal target of sodium intake. Although there are still reports and personal views not foreseeing benefits in blood pressure control by associating sodium restriction to antihypertensive drugs, there is good evidence of additive blood pressure lowering when sodium restriction is the associated with diuretics, ACE-inhibitors and beta-adrenergic blockers and Angiotensin II receptor blockers. However a reduction of sodium intake does not impact blood pressure readings in
hypertensive patients receiving calcium-channel blockers
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