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Biomedical subjects

M Ricci

Publications and source records attributed to M Ricci.

At least 37 records · Page 2Linked to original sources
PubMed2003

ALTEA: anomalous long term effects in astronauts. A probe on the influence of cosmic radiation and microgravity on the central nervous system during long flights.

The ALTEA project participates to the quest for increasing the safety of manned space flights. It addresses the problems related to possible functional damage to neural cells and circuits due to particle radiation in space environment. Specifically it aims at studying the functionality of the astronauts' Central Nervous Systems (CNS) during long space flights and relating it to the peculiar environments in space, with a particular focus on the particle flux impinging in the head. The project is a large international and multidisciplinary collaboration. Competences in particle physics, neurophysiology, psychophysiology, electronics, space environment, data analyses will work together to construct the fully integrated vision electrophysiology and particle analyser system which is the core device of the project: an helmet-shaped multi-sensor device that will measure concurrently the dynamics of the functional status of the visual system and passage of each particle through the brain within a pre-determined energy window. ALTEA is scheduled to fly in the International Space Station in late 2002. One part of the multi-sensor device, one of the advanced silicon telescopes, will be launched in the ISS in early 2002 and serve as test for the final device and as discriminating dosimeter for the particle fluences within the ISS.

Adaptation, Physiological↗
PubMed2003

Management of pulmonary venous obstruction after correction of TAPVC: risk factors for adverse outcome.

OBJECTIVE: Recurrent pulmonary venous obstruction (PVO) occurs in 0-18% of infants undergoing correction of total anomalous pulmonary venous connection (TAPVC). Limited published data suggest that PVO usually develops within 6 months of primary repair, and that outcomes of reoperations are poor. This study aimed to review our experience of reoperations for PVO post-TAPVC repair and to identify risk factors for adverse outcome. METHODS: Twenty patients underwent reoperation for PVO between 1982 and 2002. Clinical data were reviewed. TAPVC was mostly infracardiac (11 patients). TAPVC was obstructed in nine patients. PVO developed early (<6 months) in seven patients, and late in 13 (>6 months). Time of presentation was unrelated to type of PVO (anastomotic vs. ostial). Repair was accomplished using various techniques (anastomotic enlargement with native atrial tissue, enlargement with pericardium, free or in situ, or other prosthetic material). Follow-up ranged from 1 month to 15 years (average 44 months). RESULTS: Thirteen patients received one reoperation, while seven had multiple reoperations. In 13 patients, PVO was defined as new onset (no obstruction post-TAPVC repair), and in seven patients as residual (minimal obstructive changes post-TAPVC repair that progressed to PVO). Ten patients presented with anastomotic PVO, six with anastomotic and ostial PVO (involving the PVs), three with ostial PVO, and one with coronary sinus-left atrial junction stenosis. Mortality was 25% (5/20). Six of the ten patients with anastomotic PVO underwent one reoperation (2/6 died); the other four developed ostial PVO after reoperation, requiring multiple procedures (2/4 died). Mode of presentation (new onset vs. residual), site of obstruction (anastomotic vs. ostial), preoperative RV pressure (<0.8 vs. >0.8 systemic), number of reoperations (single vs. multiple), residual obstruction (presence or absence), and operative approach (Gore-tex or not) did not seem to affect outcomes. Risk factors for death were early presentation (<6 months) and persistence of pulmonary hypertension after reoperation; early presentation was also a risk factor for multiple reoperations. CONCLUSIONS: Our findings support the conclusion that early presentation and postoperative pulmonary hypertension have the greatest adverse impact on outcome. Of these, failure to achieve a low-pressure pulmonary vascular system seems to be the variable that most strongly prevents survival. In our series, neither ostial PVO nor multiple re-interventions significantly increased surgical risk. The negative impact of postoperative residual obstruction on outcome was not striking. However, an aggressive surgical approach to this disease is still warranted. Although the role of each technique in obtaining long-lasting relief of PVO remains to be established, the use of artificial material seems unwise.

Blood Vessel Prosthesis Implantation↗
PubMed2003

Screening and prevention of congenital toxoplasmosis: an effectiveness study in a population with a high infection rate.

OBJECTIVES: Secondary prevention of congenital toxoplasmosis has been attempted by screening pregnant women or by screening neonates. We compared the results of these two approaches, in order to evaluate the effectiveness of these strategies and of the antibiotic treatment of infected women. METHODS: A prenatal serological screening program for toxoplasmosis enrolled 8061 pregnant women; 9730 neonates were screened during the same period. RESULTS: Out of 5288 susceptible pregnancies, 188 were identified as infected by Toxoplasma gondii (35/1000). The transmission rate was 11.3%, with a higher rate for neonates exposed in the last trimester (relative risk 10.6); four neonates were affected. Out of 9730 screened neonates, four tested positive (0.4/1000) and one was affected. Out of a total of 163 exposed neonates, 12 were clinically affected. The rate of clinical sequelae was 31.6% among those infected and 7.4% among all exposed to infection; neonates born of women who had not been treated were more likely to be affected than treated neonates (odds ratio 4), but after adjustment for trimester of infection no significant association was found. CONCLUSIONS: Neonatal screening for toxoplasmosis seems to be less effective than pregnancy screening. Observational data do not support the effectiveness of treatment during pregnancy to prevent clinical disorders.

Animals↗
PubMed2002

Development of a low-cost technology for mass production of the free-living nematode Panagrellus redivivus as an alternative live food for first feeding fish larvae.

The free-living nematode Panagrellus redivivus is a suitable food source for first feeding fish. In the present report, a new method for the mass production of P. redivivus is presented. The technique involves multiplication of the nematode in monoxenic (single microorganism: Saccharomyces cerevisiae) solid culture (fluid media supported by 1- to 4-cm(3) sponge cubes) in autoclavable plastic bags (size range: 50 x 30 cm to 75 x 67 cm). Two growing media were tested: oat-meal medium (OM), which is an oat-based medium (16.7% oat-meal flour in 0.8% saline solution), and purified ingredient medium (PIM), a semi-synthetic medium (1.64% meat peptone, 0.94% yeast extract, 12.6% corn starch, 0.24% glucose, 1.48% sunflower oil, in 0.8% saline solution). The bags were inoculated with 350 nematodes/g medium. After an average period of 12 days (11-13 days) at 25 degrees C, the average yield (number of nematodes/g medium) was 241 x 10(3) for OM and 333 x 10(3) for PIM in 12-l bags (50 x 30 cm). The production scale has currently reached a bag volume of 50 l (75 x 67 cm); using PIM and the conditions described above, it was possible to harvest more than 1.3 x 10(9) nematodes/bag (291 x 10(3) nematodes/g medium). In PIM, when sun flower oil was replaced with the same amount of fish oil or cod liver oil, yields of 259 x 10(3) and 290 x 10(3) nematodes/g medium, respectively, were attained. The technology for mass production and formulation of P. redivivus should enable fish-hatchery operators to rely on a cheap, standardised, and permanently available live food product for first feeding fish larvae.

Animals↗
PubMed2002

New microencapsulated sunscreens: technology and comparative evaluation.

The aim of this work is to obtain new technologically improved microencapsulated sunscreens characterised by UV-radiation stability, good substantivity, low toxicity, a better tolerability and easiness to formulation. For this purpose we prepared two different systems using semisynthetic Hyaluronic Acid (HA) benzyl ester and a synthetic polymer (patent pending). We obtained these systems using two different methodologies: emulsification/solvent evaporation and emulsification/solvent extraction. The comparison between the two formulated systems was carried out in terms of their chemical-physical and biological properties.

Capsules↗
PubMed2002

Relaxation processes in an epoxy resin studied by time-resolved optical Kerr effect.

The dynamics of the epoxy resin phenyl glycidyl ether, a fragile glass-forming liquid, is investigated in the liquid and supercooled phases by time-resolved optical Kerr effect experiment with an heterodyne detection technique. We tested the mode-coupling theory and found that the predicted dynamic scenario allows to reproduce properly the measured signal, for t>1 ps, in the whole temperature interval investigated. Furthermore, the values of T(c) and lambda, obtained from the analysis of three different and independent dynamic regimes (alpha regime, von Schweidler, beta regime), are in remarkable agreement. Moreover, relaxation times obtained from optical Kerr effect and dielectric spectroscopy measurements are compared. The two time scales differ only for a constant factor in the whole temperature interval investigated.

Journal Article↗
PubMed2002

Eye light flashes on the Mir space station.

The phenomenon of light flashes (LF) in eyes for people in space has been investigated onboard Mir. Data on particles hitting the eye have been collected with the SilEye detectors, and correlated with human observations. It is found that a nucleus in the radiation environment of Mir has roughly a 1% probability to cause an LF, whereas the proton probability is almost three orders of magnitude less. As a function of LET, the LF probability increases above 10 keV/micrometer, reaching about 5% at around 50 keV/micrometer.

Aerospace Medicine↗
PubMed2001

Evaluation of in vitro percutaneous absorption of lorazepam and clonazepam from hydro-alcoholic gel formulations.

Clonazepam and lorazepam are two anxiolytics, antidepressant agents, having suitable features for transdermal delivery. The objectives of this study were to evaluate the in vitro percutaneous absorption of these drugs through excised human skin (stratum corneum and epidermis, SCE) and to determine their in vitro permeation behavior from a series of hydro-alcoholic gel formulations containing various enhancing agents. The best permeation profile was obtained for both drugs applying them together with Azone in combination with propylene glycol (PG): these enhancers were able to increase the clonazepam and lorazepam percutaneous fluxes at steady-state about threefold, compared to the free enhancer formulations (Control). To explain the mechanism of the used promoters, the benzodiazepine diffusion and partitioning coefficients from the gel containing the enhancers were calculated. The results indicated that the Azone in combination with PG could act by increasing the benzodiazepine diffusion coefficients, Transcutol increased only the SC/vehicle partition coefficients, limonene in combination with PG appeared to increase both partition and diffusion coefficients moderately, while PG did not increase both the parameters. Furthermore, to evaluate the potential application of tested benzodiazepine formulations containing Azone in combination with PG using the flux values from the in vitro experiments, the corresponding steady-state plasma concentrations (C(SS)) were calculated. The obtained calculated C(SS) values are within the lorazepam therapeutic range and suggest that transdermal delivery of this drug could be regarded as feasible.

Adult↗
PubMed2001

Improved function of rat islets upon co-microencapsulation with Sertoli's cells in alginate/poly-L-ornithine.

The purpose of this study was to assess whether Sertoli's cells would improve functional performance of homologous pancreatic islets within microcapsules. Purified rat Sertoli's cells were co-enveloped with islets in microcapsules that had been fabricated with alginic acid and poly-L-ornithine. Confocal laser microscopy was used to determine any mitogenic effects of Sertoli's cells on islets beta-cells. Insulin secretion from islets, with or without Sertoli's cells, was examined, and grafts of Sertoli's cells with islets in microcapsules into diabetic mice were carried out. Co-incubation of Sertoli's cells with islets resulted in a significant increase in the islet beta-cell mitotic rate, which was coupled with significantly higher insulin release under glucose stimulation, as compared to controls. Grafts of co-microencapsulated Sertoli's cells with islets resulted in prolongation of the achieved normoglycemia in the animals receiving Sertoli's cells with islets as compared to controls that received islets only. Sertoli's cells do promote mitogenic activities upon in vitro co-incubation with islets, whose in vitro functional and in vivo post-transplant consequences were evident. Sertoli's cells could, therefore, be co-microencapsulated with islets for transplantation in diabetic recipients.

Alginates↗
PubMed2001

Redo left anterior descending artery grafting via left anterior small thoracotomy: an alternative approach.

Reoperative left anterior descending artery (LAD) revascularization can be performed through a left anterior small thoracotomy (LAST approach) in patients requiring isolated LAD revascularization. If the left internal mammary artery has been previously used, however, the operation is generally performed either through a median sternotomy or through a full posterolateral thoracotomy for the necessity of connecting the vein graft to the ascending aorta or to the descending thoracic aorta, thus losing the advantages of a minimally invasive approach. In the case reported herein, we describe a technique in which reoperative revascularization of the LAD is accomplished through the LAST approach, using the stump of the left internal mammary artery as the inflow site of a saphenous vein coronary graft to the LAD.

Humans↗
PubMed2001

Influence of visual distractors on movement trajectory.

In the present study, we explored the influence of a visual distractor on the trajectory of movements made to join two dots. The two dots could be unconnected (D) or connected by a straight (L) or curved line, convex either to the left (LL) or to the right (RL). The connecting line constituted the visual distractor. In Experiment 1, subjects were asked to perform the joining movement as straight as possible. The results showed that hand trajectory moved to the left of the midsagittal axis in LL and to the right in RL, while it was almost straight both in L and D. In Experiment 2, subjects were explicitly required to follow the connecting line during their movements to verify whether, in the previous experiment, they had used curved lines as guide for their movements. An increase of movement time and different hand paths showed that this was not the case. In Experiment 3, subjects were asked to move as straight as possible without vision of their hand. Hand trajectories were shifted to the left in all experimental conditions, but the leftward shift was greater in LL than in all other conditions, and also greater in D and L than in RL. These findings suggest that the visual distractor influenced hand trajectory by attracting subject's attention and competing with target for motor response. It is hypothesized that the attracting influence operated by the distractor was sustained by involuntary attentional mechanisms.

Adult↗
PubMed2001

Microbiological and densitometric TLC analyses for peptides in liposomes.

Quantitative determination of Leucinostatins and/or of similar peptides, such as Peptaibols, is sometimes quite difficult to perform especially when they are entrapped in vectors, i.e. liposomes, whose components display UV absorbances that may obscure those of the active principle. Therefore, in these cases, it is useful to find alternative ways, especially when high pressure liquid chromatography (HPLC) is difficult to perform or needs long procedure times. In the present paper, the use of microbiological and densitometric methods for quantitative analysis of Leucinostatin A (Leu-A) are described and the results compared with those from HPLC analyses. The use of microbiological and densitometric assays, furnished results comparable with those obtained by HPLC. Of the two methods used, the microbiological procedure appeared to be less accurate and precise.

Chromatography, Thin Layer↗
PubMed2001

Surgical strategy for repair of large pseudoaneurysms of the aortic isthmus.

Resection of unusually large pseudoaneurysms of the aortic isthmus is complex, and involves various strategies of cardiopulmonary bypass (CPB), cerebral and spinal cord protection. We report on a patient with a giant pseudoaneurysm of the distal arch and proximal descending aorta, in whom cannulation of the femoral artery was unfeasible. Instead, the right axillary artery and the left femoral vein were cannulated. This technique allowed to perform a left anterolateral thoracotomy with the patient already on CPB and hypothermic, and to shorten the duration of hypothermic circulatory arrest.

Aneurysm, False↗
PubMed2001

The structural organisation of sperm head components of the wombat and koala (suborder: Vombatiformes): an enigma amongst marsupials.

The sperm head structural organisation of the koala and hairy-nosed wombat, and the effects of varying concentrations of the ionic detergent, Triton X-100, on its component parts, were determined by electron microscopy. Although alike in form between the 2 species, the sperm nucleus of the former, but not the latter, had nuclear vacuoles and appeared to be more easily dispersed by the Triton X-100. The structure of the acrosome of the spermatozoon was similar between the 2 species and, in both, previously undescribed thin posterior and lateral segments were found to be present. It is suggested that this thin segment may facilitate sperm-zona and/or sperm-oolemma binding and fusion.

Acrosome↗
PubMed2001

The use of telemedicine for real-time video consultation between trauma center and community hospital in a rural setting improves early trauma care: preliminary results.

BACKGROUND: By geographic necessity, rural trauma patients must be initially stabilized at local community hospitals before transfer for definitive care. In this study, it was hypothesized that telemedicine consults with trauma surgeons from a Level I trauma center online while the patient was still in the community hospital ED could positively affect care. METHODS: Four community hospital emergency departments in upstate New York and Vermont were equipped with dual cameras with remote control capability. Three trauma surgeons' homes were wired and equipped with telemedicine systems. Protocols were developed for the initiation of a telemedicine consult. RESULTS: There were 26 telemedicine consults over an 8-month period. The telemedicine population was significantly more severely injured and had a higher mortality than the general trauma population admitted to the Level I trauma center. In two cases, it was felt that the telemedicine consultation was potentially lifesaving. On follow-up, more than 80% of the referring providers felt that the telemedicine consult improved care. CONCLUSION: Telemedicine provides a virtual online trauma surgeon to assist with the resuscitation and stabilization of the major trauma patient in a small community hospital. These preliminary results show a positive impact on rural trauma patient care at the local community hospital.

Adolescent↗