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Biomedical subjects

A Sacchetti

Publications and source records attributed to A Sacchetti.

At least 19 recordsLinked to original sources
PubMed2006

Far-infrared absorption of La1-xCaxMnO3-y at high pressure.

The first far-infrared absorption spectra of manganite samples at pressures P up to 10 GPa were obtained on La1-xCaxMnO3-y by use of synchrotron radiation. For x=0.25 and 0.20 (y=0), P promotes partial metallization at room temperature through a strong reduction of the insulating gap. An x=0.20 sample with y=0.08 does not show any charge delocalization effect up to 10 GPa. An Urbach-like model of disordered Jahn-Teller wells is shown to well fit the far-infrared band edge and allows one to obtain a reliable pressure dependence of the energy gap.

Journal Article↗
PubMed2006

The safety of single-physician procedural sedation in the emergency department.

BACKGROUND: Previous research has shown the safety of procedural sedation in the emergency department in university settings involving multiple emergency physicians. OBJECTIVE: To examine sedation in the emergency department conducted by a single emergency physician with monitoring by the emergency nurse. METHODS: The Procedural Sedation in the Community Emergency Department Registry is a prospective observational database of procedural sedation cases directed by the emergency physicians. Among other parameters, the registry tracts whether emergency physicians or emergency nurses monitored patient sedation. The incidence of complications and outcomes were compared between these two monitoring groups. RESULTS: 1028 procedural sedations were performed on 977 patients at 14 sites. In 885 (86.1%) cases the emergency physician directed the sedation, and performed the procedure with monitoring by the emergency nurse. Complications occurred in 42 (4.1%) patients, 35 (4.0%) EN monitored patients and 6 (4.2%) EP monitored patients (p>0.7). Procedures were successful in 863 (97.5%) cases monitored by emergency nurses and in 140 (97.9%) patients monitored by emergency physicians (p>0.7). CONCLUSION: Procedural sedation in the emergency department performed by a single emergency physician is safe and effective.

Clinical Competence↗
PubMed2005

A comparative EPR, infrared and Raman study of natural and deproteinated tooth enamel and dentin.

The aim of the present work was to investigate how the native signal observed in the electron paramagnetic resonance (EPR) spectrum of tooth enamel and dentin is associated with the organic content of the two tissues. This was achieved by comparing the EPR native signal and the optical bands (Raman and infrared, IR) associated with organic components of tooth enamel and dentin, in natural and deproteinated samples. The main results were: (a) in natural samples, the organic optical bands are more intense in dentin than in enamel, in contrast with the EPR native signal which shows similar intensity in the two tissues; (b) after deproteination, the optical organic bands are completely suppressed in both dentin and enamel, while the EPR native signal is eliminated only in dentin. It is suggested that the IR and Raman organic bands are originated in the bulk of the organic matrix, while the paramagnetic centres associated with the EPR native signal are located in the organic-mineral interface.

Dental Enamel↗
PubMed2003

Pressure tuning of electron-phonon coupling: the insulator to metal transition in manganites.

An extended temperature and pressure-dependent investigation is carried out on a La0.75Ca0.25MnO3 sample exploiting the infrared absorption technique coupled to a diamond anvil cell. The pressure dependence of the insulator to metal transition temperature T(IM) is determined for the first time up to 11.2 GPa. The T(IM)(P) curve we propose to model the present data has an exponential-like behavior with an associated characteristic pressure P* playing the role of a decay constant. It is found that the equivalence between an external and an internal (chemical) pressure holds over a limited range of pressure, namely, P< or =2P*. Moreover, a certain universality character is associated with the proposed model curve in its ability to account for a large class of low-disorder manganites characterized by intermediate electron-phonon coupling.

Journal Article↗
PubMed2001

Efficient GFP mutations profoundly affect mRNA transcription and translation rates.

Green fluorescent protein (GFP) variants with higher expression efficiencies have been generated by mutagenesis. Favorable mutations often improve the folding of GFP. However, an effect on protein folding fails to explain the efficiency of several other GFP mutations. In this work, we demonstrate that mutations of the GFP open reading frame and untranslated regions profoundly affect mRNA transcription and translation efficiencies. The removal of the GFP 5' untranslated region halves the transcription rate of the GFP gene, but hugely improves its translation rate. Mutations of the GFP open reading frame or the addition of peptide sequences differentially reduce the GFP mRNA transcription rate, translation efficiency and protein stability. These previously unrecognized effects are demonstrated to be critical to the efficiency of GFP mutants. These findings indicate the feasibility of generating more efficient GFP variants, with optimized mRNA transcription and translation in eukaryotic cells.

5' Untranslated Regions↗
PubMed2001

Green fluorescent protein variants fold differentially in prokaryotic and eukaryotic cells.

Better-folding Green Fluorescent Protein (GFP) mutants selected from bacterial screenings are commonly used in widely different cellular environments. However, it is unclear if the folding efficiency of GFPs is invariant in different cell types. In this work, we have analysed the folding properties of GFP variants in bacteria versus mammalian cells. Remarkably, S65T was found to fold at comparable levels with the wild type GFP in bacteria, but at 10-fold lower levels in mammalian cells. On the other hand, Bex1 folded 3-4 times better than the wtGFP or S65T in E. coli, and 10-20-fold or more than 95-fold better, respectively, in mammalian cells. The Vex1 mutant demonstrated similar properties to Bex1. No evidence of differential GFP unfolding in vivo or of preferential degradation of unfolded GFP molecules was found. Moreover, no relationship between GFP folding efficiency and expression levels, or protein stability was detected. Trivial Aconfounding factors, like GFP unfolding caused by different pH or fluorescence quenching due to molecular crowding, were also excluded. In summary, our results demonstrate that specific GFP variants follow different folding trajectories in mammalian versus bacterial cells. The specificity of this differential folding supports a role of chaperones in guiding the folding of GFP in vivo. J. Cell. Biochem. Suppl. 36: 117-128, 2001.

Animals↗
PubMed2000

Acceptance of family member presence during pediatric resuscitations in the emergency department: effects of personal experience.

OBJECTIVE: Opinions remain polarized on allowing family member presence during pediatric resuscitations (FMP). Reluctance to adopt FMP may stem from preconceived notions on this practice. This study evaluates the effect of prior experience with FMP and on its acceptance by emergency department personnel (EDP). METHODS: EDP from three different EDs were surveyed concerning FMP. Study facilities included an urban teaching community ED with routine FMP (R-ED), a suburban community ED with occasional FMP (O-ED) and an urban university pediatric ED with virtually no FMP (N-ED) during pediatric resuscitations. Survey information included hospital of practice, position in ED, years in practice, opinions on FMP and personal experience with FMP for five clinical scenarios: laceration repair (LAC), intravenous access (IV), lumbar puncture (LP), endotracheal intubation (ETI), cardiopulmonary resuscitation (CPR), and critical resuscitation (CR). Statistical analysis was through chi square and regression analysis. RESULTS: Eighty-five emergency department personnel participated in the survey, 57 (67%) nurses, 22 (25%) physicians, 4 technicians (5%), and 2 nurses aids (2%). There was a significant correlation between a favorable opinion concerning family member presence during LP, ETI, CPR and CR and the type of Emergency Department in which the individual practiced (P<0.002). Regression analysis demonstrated a similar relation between personal experience with LAC, IV, ETI, CR, and CPR and a favorable opinion on FMP during that activity (P<0.03). CONCLUSION: Opinions on FMP are strongly influenced by experience with this practice. Emergency department personnel with prior exposure to family member presence during resuscitations favor this activity. Biases by EDP lacking experience with FMP may limit its introduction into unfamiliar institutions.

Attitude of Health Personnel↗
PubMed2000

The potential for errors in children with special health care needs.

Children with special health care needs (CSHCN) are at risk for suboptimal treatment when presenting for emergent care to unfamiliar health care providers. Errors in their management may stem from failure to recognize occult conditions, lack of familiarity with rare or complex medical problems, or lack of prior knowledge of baseline physical findings. An emergency information form (EIF) that contains patient-specific information on essential diagnostic and therapeutic interventions may provide a ready personal reference for the emergent care of CSHCN. Coupled with the use of medical identification jewelry and an electronic transmission system, an EIF has the potential to eliminate management errors in the care of these patients.

Child↗
PubMed2000

Should pediatric emergency care be decentralized?: an out-of-hospital destination model for critically ill children.

OBJECTIVES: A time-to-initial-stabilization model for out-of-hospital destinations of critically ill children (CICs) was developed. Application of this model to assess the impact of changes in different parameters of an emergency medical services for children (EMSC) system is described. METHODS: A computer model created a 2,500-square-mile community containing ten community hospitals (CHs) and one pediatric critical care center (PCC). Community hospitals capable of providing initial immediate stabilization of CICs were defined as emergency departments accepting pediatrics (EDAPs). Critically ill children were randomly selected in proportion to population densities across the modeled community. Time to initial stabilization (TIS) was defined as the time to arrival at either an EDAP or a PCC or time to arrival at a non-EDAP CH + travel time for a team from the PCC to the non-EDAP CH + preparation/dispatch (P/D) time. The following parameters of the model were varied and their effect on TIS was evaluated: location of CHs, location of PCC, primary destinations for CICs, percent of CHs meeting EDAP standards, out-of-hospital compliance with designated hospitals for CICs, P/D time, and ambulance speed. RESULTS: The computer model selected 1,000 CICs in accordance with the population densities of the community. The scenario with the shortest TIS was one in which every CH achieved EDAP designation (9.8 +/- 0.5 minutes). The scenario with the longest TIS involved a model in which every CIC was transported directly to the PCC (28.6 +/- 0.33 minutes). The number of EDAPs in a community and out-of-hospital compliance with use of EDAPs produced comparable effects on the TIS. Travel speeds had a direct effect on TIS but also exaggerated inefficiencies between scenarios. The P/D time had little effect on the TIS. CONCLUSIONS: An out-of-hospital destination model has been developed with the ability to modify multiple EMSC system variables. Application of this model demonstrates the shortest times to stabilization of critically ill children occur in systems that maximize the number of hospitals that meet EDAP standards and decentralize pediatric emergency care.

Adolescent↗
PubMed2000

The molecular determinants of the efficiency of green fluorescent protein mutants.

The Green Fluorescent Protein (GFP) is a spontaneously fluorescent polypeptide of 27 kD from the jellyfish Aequorea victoria that absorbs UV-blue light and emits in the green region of the spectrum. GFP has been successfully expressed both in bacteria and in eukaryotic cells and is widely used to monitor the localization of tagged proteins in living cells. Since wtGFP performs inefficiently in different cellular contexts, efforts have been devoted to the improvement of GFP expression levels and/or fluorescence. We will here review the basic characteristics of wt and mutated GFP, in particular their protein expression vs fluorescent properties. Emphasis will be given to unexpected consequences of mutations of the GFP gene, i.e. on transcription and translation rates and on protein folding in different cell types, and to how these critically reflect on the use of GFP in different cellular environments.

Animals↗
PubMed1999

ED hemodialysis for treatment of renal failure emergencies.

Patients with chronic renal failure (CRF) are at risk for unique medical emergencies, many of which require hemodialysis for their definitive treatment. This study describes the use of emergency department (ED) hemodialysis in the management of CRF patients. A retrospective chart review was conducted of patients who underwent ED hemodialysis at a regional dialysis center between April 1994 and September 1996. Data were collected on presenting complaint, ED diagnosis, indication for hemodialysis, ED pharmacologic treatment, ED airway management, cardiovascular stability, and disposition. Fifty episodes of ED hemodialysis were identified in 37 different patients. Presenting complaints included: shortness of breath, 38 (69%); weakness, 8 (15%); chest pain, 3 (5%); and other, 6 (11%). ED diagnoses included: congestive heart failure, 36 (65%); hyperkalemia, 13 (24%); and other, 6 (11%). Indications for hemodialysis included: cardiovascular instability, 33 (38%); respiratory distress, 22 (26%); cardiac monitoring, 16 (19%), timing, 13 (15%); and other, 2 (2%). Predialysis stabilization included: nitroglycerin, 29 (26%); sublingual captopril, 17 (15%); calcium chloride, 13 (11%); sodium bicarbonate, 12 (11%); insulin/dextrose, 11 (10%); none, 12 (11%); and other, 18 (16%). Airway support included: noninvasive pressure support ventilation (NPSV), 9 (18%); and endotracheal intubation, 6 (12%). NPSV was provided with a bilevel positive airway pressure system. Three of the endotracheal intubation patients were weaned to NPSV during dialysis, and all NPSV patients were weaned from respiratory support during their hemodialysis in the ED. Some patients had more than one problem. Sixteen patients (32%) were admitted, while 34 (68%) were discharged, including 3 NPSV patients and 22 initially unstable patients. ED hemodialysis in conjunction with additional medical care is a useful emergency medicine technique that can prevent hospital admission in patients with acute renal emergencies.

Acute Disease↗
PubMed1999

Effect of ED management on ICU use in acute pulmonary edema.

Acute pulmonary edema (APE) is a common Emergency Department (ED) presentation requiring admission to an intensive care unit (ICU). This study was undertaken to examine the effect of ED management on the need for ICU admission in patients with APE. ED records of APE patients were abstracted for patient age, prehospital and ED pharmacological treatment, diagnoses, airway interventions, and ICU length of stay (LOS). Statistical analysis was through multiple regression, logistic regression, chi-square, and ANOVA. One hundred eighty-one patients composed the study group. Pharmacological treatment included nitroglycerin (NTG), 147 patients (81%); morphine sulfate (MS), 88 (49%); loop diuretics (LD), 133 (73%); and captopril sublingual (CSL), 47 (26%). Use of CSL and MS were associated with opposing needs for ICU admission. MS use was associated with increased ICU admissions (odds ratio, 3.08; P = .002), whereas CSL use was associated with decreased ICU admissions (odds ratio, 0.29; P = .002). Morphine sulfate use also demonstrated an increased need for endotracheal intubation (ETI) (odds ratio, 5.04; P = .001), whereas CSL demonstrated a decreased need for ETI (odds ratio, 0.16; P = .008). Ninety-three patients required some form of respiratory support. Forty received noninvasive pressure support ventilation (NPSV) from a bilevel positive airway pressure system (BiPAP), and 60 received endotracheal intubation. Some patients received more than 1 form of respiratory support; all other patients received supplemental oxygen only. The ICU-LOS associated with different airway interventions were supplemental oxygen, 0.72 days; BiPAP, 1.48 days; and ETI, 3.70 days (P < .001). Specific ED pharmacological interventions are associated with a decreased need for ICU admission and endotracheal intubation in acute pulmonary edema patients, whereas use of noninvasive pressure support ventilation correlates with a reduction in the ICU length of stay for patients who do require critical care admission.

Acute Disease↗