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Biomedical subjects

L Urbani

Publications and source records attributed to L Urbani.

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

Management of massive and persistent ascites and/or hydrothorax after liver transplantation.

PURPOSE: To describe the results of the treatment of eight liver transplantation (LT) patients subsequently developing large volumes of long-lasting ascites. PATIENTS AND METHODS: Between August 1996 and February 2003, 405 LTs were performed in 375 patients, eight (1.97%) of whom (six men and two women of mean age of 55.4 +/- 5.2 years) subsequently developed massive (> 500 mL/d) and persistent ascites and/or hydrothorax. All patients were HCV positive. The mean age of the liver donors was 66.8 +/- 21.9 years. All LTs were performed by replacement of the recipient retrohepatic vena cava. RESULTS: The eight patients displayed sinusoidal portal hypertension related to biopsy-proven recurrence of HCV infection. Mean wedged hepatic venous pressure was 14.9 +/- 5.1 mm Hg and mean portal vein/right atrial pressure gradient (PAPG) was 17.3 +/- 4.8 mm Hg. In two patients, the ascites appeared the day after LT; in the remaining six, ascites and/or hydrothorax appeared after 342.3 +/- 167.7 days. Seven patients with a mean PAPG of 18.4 +/- 3.9 mm Hg and a mean plasma/ascites albumin concentration gradient of 2.8 +/- 0.3 g/L were treated by means of a trans-jugular intrahepatic portosystemic shunt TIPS, and one (with a PAPG of 9 mm Hg and a plasma/ascites albumin concentration gradient of 1.38 g/L) by means of spleen arterial embolisation. After a mean follow-up of 558 +/- 147.2 days, the ascites and/or hydrothorax have resolved in five patients (62.5%), one (12.5%) has stable ascites not requiring paracentesis, and two (25%) have died of multiorgan failure. CONCLUSIONS: These data suggest the efficacy of the aggressive treatment of massive and persistent ascites and/or hydrothorax.

Ascites↗
PubMed2003

Surgical complications after liver transplantation.

AIM: The number of liver transplantations in Italy has steadily increased over the last 10 years as a result of the use of donors aged more than 60 years. The use of organs with a reduced functional reserve has been compensated for by improvements in immunosuppressive therapy, surgical techniques and the management of postoperative complications. This article describes the incidence and treatment of the main surgical complications after liver transplantation. METHODS: Between January 1996 and June 2003, 398 patients received 430 transplants at our Centre. Thirty-seven early relaparotomies were performed (8.6%), including 12 retransplantation (2.8%). The 1-, 3- and 5-year actuarial survival of the patients was 79.8%, 72.2% and 67.5%, and that of the grafts was 75.9%, 68% and 63.4%. Perioperative mortality was 10.5% (with no intraoperative deaths). RESULTS: The overall incidence of biliary complications was 31.6%, 9.1% of which were due to the removal of the Kehr tube. There were 42 (9.8%) anastomotic stenoses, 5 (1.2%) extra-anastomotic stenoses, 1 (0.2%) anastomotic leak, 5 (1.2%) extra-anastomotic leaks, and 19 (4.4%) ischemic-type biliary lesions. The overall incidence of vascular complications was 6.9%: 7 (1.6%) cases of hepatic artery thrombosis, 17 (4.0%) arterial stenoses, 1 (0.2%) arterial pseudoaneurysm, 4 (0.9%) cases of portal thromboses and 1 (0.2%) case of caval laminar thrombosis. Eight patients (1.9%) developed massive and persistent post-transplant ascites and/or hydrothorax. CONCLUSION: The use of donors aged more than 60 years makes it possible to maintain high standards of patient and graft survival that is not only due to the optimisation of immunosuppressive protocols, but also to improvements in surgical techniques, intensive care and the management of surgical complications.

Adolescent↗
PubMed2000

A complementary relationship between wake and REM sleep in the auditory system: a pre-sleep increase of middle-ear muscle activity (MEMA) causes a decrease of MEMA during sleep.

Since some evidence has supported a complementary relationship between waking and REM-sleep eye movement (variations in frequency, amplitude, or direction of waking saccades have been found to inversely affect the corresponding parameters of rapid eye movements), the present study assessed whether this relationship can also be shown for other phasic components of REM sleep, such as middle-ear muscle activity (MEMA), as a consequence of an increase of middle-ear reflex frequency during pre-sleep wake. Ten subjects were studied in three consecutive nights (one adaptation, one baseline, one experimental). In the experimental night, subjects underwent a 2-h pure-tone (1000 Hz, 90 dB SPL) auditory stimulation and MEMA was monitored every 15 min; noise exposure during daytime was also controlled. Results show that MEMA frequency during REM sleep significantly decreased during the experimental nights compared with baseline nights, while each sleep variable as well as mean daily auditory input did not present any significant difference between baseline and experimental nights. Results suggest that the complementary relationship between wake and REM sleep is not bounded to oculomotor activity, but it may also be extended at least to middle-ear muscle phasic activity.

Acoustic Stimulation↗
PubMed2000

Oculomotor impairment after 1 night of total sleep deprivation: a dissociation between measures of speed and accuracy.

OBJECTIVES: The present study examined the effects of 40 h of sleep deprivation and of time-of-day on saccadic and smooth pursuit oculomotor performance. METHODS: Nine normal subjects slept for 3 consecutive nights in the laboratory (one adaptation, one baseline, one recovery). Baseline and recovery were separated by a period of 40 h of continuous wakefulness, during which subjects were tested every 2 h. Oculomotor performance assessed at the following hours: 10:00, 12:00, 14:00, 16:00, 18:00, 20:00, 22:00, of both the days preceding and following the sleep deprivation night, as well as at 24:00, 02:00, 04:00, 06:00 and 08:00 h during the deprivation period. RESULTS: Saccade latency increased and peak velocity decreased significantly during the post-deprivation day; saccadic accuracy was unaffected. As regards smooth pursuit performance, phase (a measure of accuracy) was not affected by sleep loss, while velocity gain significantly decreased during the day that followed the sleep deprivation night. Significant time-of-day effects on the considered oculomotor variables except saccadic accuracy were also found, indicating an overall performance impairment during the night. CONCLUSIONS: It is concluded that 40 h of sleep deprivation significantly impaired diurnal performance in pursuit and saccadic tasks. This performance worsening is limited to the measures of speed, while accuracy is not affected by sleep loss. A significant operational relevance of these results is suggested, since saccadic velocity has recently been found to be negatively correlated with simulator vehicle crash rates.

Adult↗
PubMed1999

The centrosome.

Explore the source record for details and available documents.

Animals↗
PubMed1999

Lipoprotein (a) and apoprotein B in an apparently healthy population of fighter pilots and ground personnel: their significance as potential markers of atherosclerosis.

BACKGROUND: Individuals who carry cardiovascular risk factors (CVRF) have a higher incidence of cardiovascular pathology. Among the most commonly screened CVRF are apoprotein A and B and lipoprotein (a), which represent 'independent' risk factors for atherosclerosis. In the air force community, cardiovascular pathology has been reported as the primary reason for grounding pilots. DESIGN: The aim of this study was to evaluate the frequency of CVRF in an apparently healthy population of military fighter pilots (group B, n = 50), and military ground personnel (group A, n = 50) who were matched for age, sex and body mass index but not involved in flight activity, and to evaluate whether any particular pattern of CVRF might be related to flight. METHODS: Each subject fasted overnight, and underwent the following measurements: blood pressure and resting ECG recording; and determination of serum levels of total and high-density lipoprotein cholesterol, triglycerides, uric acid and plasma levels of glucose. In addition, serum levels of apolipoprotein A, B and lipoprotein (a) were detected. RESULTS: An overall risk index for coronary artery disease was calculated using the Framingham equation. This risk index was slightly but not significantly increased in group A compared with group B. By contrast, a significant increase in both apoprotein B (P < 0.005) and lipoprotein (a) (P < 0.0005) was found in group B compared with group A. No significant differences between groups were detected for the other parameters evaluated. CONCLUSIONS: We suggest the presence in group B of an underlying trend towards the development of atherosclerosis, which may not be identified by a routine approach. Moreover, on a purely theoretical basis with no experimental evidence, the issue of the possible pathophysiological mechanism of these findings and their relationship to flight environment is also addressed.

Adult↗
PubMed1998

Smooth pursuit and saccadic eye movements as possible indicators of nighttime sleepiness.

Sleepiness is associated with specific variations of spontaneous oculomotor activity. During nocturnal sleep onset periods and also during the Multiple Sleep Latency Test (MSLT) a reduction of both rapid eye movements and blinks are recorded. In many operational contexts it might be even more relevant to assess whether and to what extent voluntary visual ocular control is affected by sleepiness due to sleep deprivation and time-of-day effects. In this study we evaluated, in a laboratory simulation of a sudden inversion of the sleep-wake cycle, the nocturnal modifications of smooth pursuit (SP) and saccadic (SAC) eye movements as possible indicators of sleepiness. Levels of sleepiness were objectively measured by means of MSLT and Maintenance of Wakefulness Test (MWT); subjective ratings of sleepiness were also obtained. After a diurnal sleep, five subjects underwent four nocturnal test sessions, each one comprising an SP and a SAC trial. Both the SP variables considered (velocity gain and phase) showed a trend similar to that one of MWT latencies, being significantly impaired only in the last nocturnal trial, when levels of sleepiness were maximal. Saccadic accuracy showed the same trend, being negatively affected by sleepiness only in the last nocturnal session. In addition, percentage of rejected (inappropriate) saccades showed a linear increase during the night, paralleling the shortening of sleep latency at MSLT and the linear increase of subjective ratings of sleepiness. These results, suggesting that saccadic performance, unlike SP, seems to be more sensitive to increasing levels of sleepiness, encourage further research on this topic.

Adult↗
PubMed1998

Predominant role of the Fab fragment in delaying hyperacute rejection in guinea pig-to-rat xenotransplantation.

BACKGROUND: Human intravenous immunoglobulin G delayed xenogeneic hyperacute rejection (HAR) in the guinea pig-to-rat combination. We investigated the respective roles of the Fc and Fab fragments of the IgG molecule in this inhibitory effect. METHODS: By using a guinea pig-to-rat heart transplantation model, the efficiency of IgG, Fab, and Fc in prolonging the grafted heart's survival time (ST) was compared. RESULTS: A dose-dependent increase in the ST was observed with Fab (r=0.74, P < 0.0001), IgG (r=0.57, P < 0.001), and Fc (r=0.51, P < 0.01). The linear regression slopes with Fab and with IgG were, respectively, sevenfold and fourfold steeper than with Fc. The ST was significantly longer than controls (23+/-7 min) after infusion of 2 g/kg IgG (147+/-42 min) or 1 g/kg Fab (176+/-38 min), whereas the highest dose of Fc (1.5 g/kg) did not induce significant prolongation of ST. In terms of equivalent functional doses, 1 g/kg Fab was significantly more potent in prolonging the ST than 1.5 g/kg IgG (87+/-25 min) or 0.5 g/kg Fc (33+/-14 min). Analysis of the rejected hearts evidenced edema, necrosis, and rat C3 deposits characteristic of HAR. CONCLUSION: These results indicated that the delaying action of intravenous immunoglobulin G on HAR in the guinea pig-to-rat combination is mostly mediated through the Fab fragment.

Animals↗
PubMed1998

The mammalian gamma-tubulin complex contains homologues of the yeast spindle pole body components spc97p and spc98p.

gamma-Tubulin is a universal component of microtubule organizing centers where it is believed to play an important role in the nucleation of microtubule polymerization. gamma-Tubulin also exists as part of a cytoplasmic complex whose size and complexity varies in different organisms. To investigate the composition of the cytoplasmic gamma-tubulin complex in mammalian cells, cell lines stably expressing epitope-tagged versions of human gamma-tubulin were made. The epitope-tagged gamma-tubulins expressed in these cells localize to the centrosome and are incorporated into the cytoplasmic gamma-tubulin complex. Immunoprecipitation of this complex identifies at least seven proteins, with calculated molecular weights of 48, 71, 76, 100, 101, 128, and 211 kD. We have identified the 100- and 101-kD components of the gamma-tubulin complex as homologues of the yeast spindle pole body proteins Spc97p and Spc98p, and named the corresponding human proteins hGCP2 and hGCP3. Sequence analysis revealed that these proteins are not only related to their respective homologues, but are also related to each other. GCP2 and GCP3 colocalize with gamma-tubulin at the centrosome, cosediment with gamma-tubulin in sucrose gradients, and coimmunoprecipitate with gamma-tubulin, indicating that they are part of the gamma-tubulin complex. The conservation of a complex involving gamma-tubulin, GCP2, and GCP3 from yeast to mammals suggests that structurally diverse microtubule organizing centers such as the yeast spindle pole body and the animal centrosome share a common molecular mechanism for microtubule nucleation.

3T3 Cells↗
PubMed1998

Influence of a 6-8 kHz audiometric notch on transient evoked otoacoustic emissions.

Thirty-eight patients with known unilateral cochlear hearing loss at 6 and/or 8 kHz were examined for transient evoked otoacoustic emissions (TEOAEs). These findings were compared with those of the contralateral "normal hearing" ear. Statistically significant lower values of echo reproducibility and amplitude were recorded in hearing-impaired ears, together with a more narrow TEOAE spectrum. In addition to these findings, a globally reduced amplitude of the cochlear response was found that was unrelated to the frequency impaired in pure-tone audiometry (6, 8, or 6-8 kHz). Since patients' audiometric thresholds at such frequencies could influence test results, findings could possibly be due to an altered echo travelling wave across the most basal part of the cochlea or to coexisting damage in the rest of Corti's organ that were undetectable with standard audiometry. A significant overlap was found between the results from hearing-impaired ears and those from normally hearing ones. Although TEOAEs were not helpful in the present study in identifying patients with a unilateral hearing loss at 6 and/or 8 kHz when compared to normal contralateral ears, they are still considered to play an important role in the follow-up of subjects at risk for hearing damage.

Adult↗
PubMed1997

[Oxygen consumption by indirect calorimetry and Fick equation in swine: role of cardiac output].

OBJECTIVES: To compare O2 uptake values measured by indirect calorimetry (VO2R) with Fick-derived values (VO2Fick) over a wide range of VO2 in experimental conditions and to analyze the influence of cardiac output (QC) on the difference between VO2R and VO2Fick. STUDY DESIGN: Animal study. MATERIAL: Nineteen 2.5-month-old, 29.2 +/- 2.8-kg, Large White pigs. METHODS: A step-by-step decrease in venous return was obtained either by haemorrhage or progressive inferior vena cava and portal veins clamping. Measurements, of 5 to 7 minutes duration included VO2R (Deltatrac), thermodilution QC and arterial and mixed venous blood O2-content. The VO2 values were compared using Bland and Altman's bias analysis. The relationship between QC values and relative error (ER = [VO2R - VO2Fick]/0.5x[VO2R + VO2Fick] was analyzed using a Spearman rank correlation coefficient. RESULTS: The VO2R and VO2Fick arithmetic mean ranged from 108 to 253 mL.min-1 in 130 measurements with broad limits of agreement between both methods. On average, VO2R values were higher than VO2Fick values by +15 +/- 25 mL.min-1. ER significantly decreased with QC (rs = 0.417; P = 0.0001). CONCLUSION: VO2R values exceed VO2Fick values. This bias does not occur in the low QC range, presumably owing to artifactual over estimation of thermodilution QC.

Animals↗
PubMed1997

[Influence of hypoxia on the human auditory system].

The present paper presents a review of the literature on "hypoxia and human auditory mechanisms". It examines and discusses, above all, the results obtained in the various studies using pure tone audiometry and auditory evoked potentials. At the present time, the two areas which appear most sensitive to hypoxia are the cochlea and, above all, the telencephalic auditory cortex (specifically those sectors dedicated to cognitive processing of auditory stimulation). However, many other areas which are sensitive to hypoxia, but to a lesser extent, have also been identified, even in other sectors of the auditory pathway. Particularly worthy of note is the effectiveness of the metabolic compensatory mechanisms which come into play upon hypoxic stress. These mechanisms include vasodilation and the presence of metabolic reservoirs. Nevertheless, there are still a number of open questions regarding how the auditory pathway functions in the case of hypoxia; thus the experimental study of hypoxic hypoxia is still an interesting, fruitful research field in audiology.

Auditory Cortex↗
PubMed1996

The Epley maneuver for the treatment of benign paroxysmal positional vertigo.

In recent years, different forms of physical therapy have been proposed for the treatment of benign paroxysmal positional vertigo (BPPV). These mainly consist of maneuvers aiming to reposition and disperse free-floating endolymph particles in the posterior semicircular canal. We report our experience with one of these procedures, the Epley maneuver (EM), in treating 30 cases of BPPV. Twenty-six patients (87%) were cured, while four (13%) did not respond to treatment. These results are similar to those reported in the literature for the EM and the Semont maneuver.

Adult↗
PubMed1996

Evaluation of stress induced by flight activity by measuring the hormonal response.

The aim of the present study was to quantitatively investigate the different levels of adaptation to flight and to evaluate the hormonal response to flight activity as a possible reliable tool to quantify the level of stress induced by flight. The hormonal response of growth hormone (GH), cortisol, and prolactin (PRL) to flight activity was evaluated in a group of student pilots (n = 11; all male; age 20 +/- 2 years) and flight instructors (n = 11; all male; age 27 +/- 2 years) of an Italian Air Force flight school. Blood samples were obtained immediately before and after a training flight session. Hormonal determination by RIA technique after flight showed a significant increase of plasma hormonal levels of GH, PRL, and cortisol in the students. Conversely, in the instructors only GH showed a significant increase versus preflight values, whereas PRL and cortisol did not show significant differences. Moreover, preflight hormonal levels of GH and PRL were significantly higher for student pilots compared to the same values for flight instructors. The data lead to establishing a close correlation between the hormonal response to flight activity and the level of tolerance and adaptation to flight-induced stress.

Adaptation, Physiological↗