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Biomedical subjects

E Mazza

Publications and source records attributed to E Mazza.

At least 19 recordsLinked to original sources
PubMed2006

Ultrasonic surface crack characterization on complex geometries using surface waves.

The characterization of surface cracks on complex geometries using surface waves is investigated numerically and experimentally. The specimen geometry is implemented in a finite difference code by approximation of the contour using a Cartesian grid. In the experiments the out-of-plane surface displacement is measured by means of a heterodyne laser interferometer. Good agreement is shown by comparison of the calculated out-of-plane displacement with experimental results for both cracked and non-cracked specimens. The crack depth is measured down to a size of 0.7 times the surface wavelength using a time delay approach. The many Rayleigh pulses propagating after the crack can be separated from the other modes by a filtering procedure based on the surface wave propagation velocity. Only a detailed analysis of the scattering phenomenon using the simulation allows an identification of the transmitted pulse required for crack depth measurement. Application of the method to a specimen with a real fatigue crack shows a systematical error possibly due to the inclined crack profile.

Journal Article↗
PubMed2006

Perioperative fluid management in kidney transplantation: is volume overload still mandatory for graft function?

Kidney transplantation is now recognized as the treatment of choice for patients with chronic renal failure. Despite the extension of indications to patients suffering severe hypertension, ischemic heart disease, and chronic heart failure, the worldwide results are superb. However, perioperative cardiac complications occur in 6% to 10% of transplanted patients. Aggressive intraoperative volume expansion is still recommended to maximize graft functional recovery (up to 30 mL/kg/h, central venous pressure [CVP] > 15 mm Hg), but patients with preexistent cardiac disease or poor myocardial function are exposed to the risk of fluid overload, acute respiratory failure, and prolonged ventilation. Among the last 90 cases performed at our institution, good functional recovery of the graft was present in 94% of the patients within 2 weeks, despite a much more conservative intraoperative hydration policy (crystalloids 2400 +/- 1000 mL, 15 mL/kg/h, CVP 7-9 mm Hg). Graft failure which occurred in 5 patients was significantly correlated only with donor age, while perioperative cardiovascular complications had been present in 9 cases (10%) who were coronary artery disease patients (55%). Age above 50 years was the only significant risk factor. Supranormal volume loading is probably not always warranted in kidney transplantation.

Atherosclerosis↗
PubMed2005

Nonlinear elastic-viscoplastic constitutive equations for aging facial tissues.

This paper reports on the initial stages of a project to simulate the nonlinear mechanical behavior of an aging human face. A cross-section of the facial structure is considered to consist of a multilayered composite of tissues with differing mechanical behavior. The constitutive properties of these tissues are incorporated into a finite element model of the three-dimensional facial geometry. Relatively short time (elastic-viscoplastic) behavior is governed by equations previously developed which are consistent with mechanical tests. The long time response is controlled by the aging elastic components of the tissues. An aging function is introduced which, in a simplified manner, captures the observed loss of stiffness of these aging elastic components due to the history of straining as well as other physiological and environmental influences. Calculations have been performed for 30 years of exposure to gravitational forces. Progressive gravimetric soft tissue descent is simulated, which is regarded as the main indication of facial aging. Results are presented for the deformations and stress distributions in the layers of the soft tissues.

Aging↗
PubMed2004

Case report: Pseudomonas aeruginosa-related intervertebral discitis in a young boy with medulloblastoma.

We report a case of a 15-year-old boy with desmoplastic medulloblastoma of the posterior fossa (T3M3, according to Chang classification) incompletely resected, with leptomeningeal and nodular spread in the posterior fossa and in the cervical and thoracic tracts of the spine, treated with sequential high dose iv chemotherapy and with hyperfractionated cranio-spinal radiotherapy. While on maintenance chemotherapy, the boy developed fever and septic status caused by Pseudomonas aeruginosa, and 1 week later also low back pain. Magnetic resonance imaging (MRI) demonstrated abnormal signal in the fourth ventricle and in the dorso-lumbar tract suggesting medulloblastoma recurrence, so he started with a chemotherapy program. Due to a worsening of back pain, a second MRI of the spine was performed that showed a spondilodiscitis of T11-T12 and L1-L2 discs. The histological and cultural examination of a fine-needle biopsy of the L1-L2 disc revealed the presence of P. aeruginosa. So patient was treated with intensive antibiotic therapy with resolution of the infection. Spondilodiscitis is a rare complication in neoplastic patients, maybe due to either immunodeficient status or invasive procedures such as lumbar puncture. This case demonstrates that MRI is a useful method for differentiating between infection and malignancy in the spine, but sometimes it may be difficult to distinguish metastatic tumor from a lesion due to spondilodiscitis. In this case surgicopathological assessment is crucial and mandatory.

Adolescent↗
PubMed2004

A finite element model for the simulation of hydrometra.

The behaviour of the human uterus under an internal (intracavital) pressure of 150 mm Hg (20 kPa) was modelled. The application of such an intracavital or intrauterine pressure corresponds to the procedure which is performed at the beginning of hysteroscopy (hydrometra). Homogenous, isotropic material laws were implemented in a three dimensional, finite element model. The volume of the distended uterine cavity was calculated with different parameters obtained from in vivo aspiration experiments on human uteri as well as from ex vivo tensile tests on rabbit uteri for comparison purposes. The calculated results were in general agreement with in vivo measurements of hydrometra performed at the University Hospital of Zurich.

Animals↗
PubMed2004

[Day surgery in breast reconstructive surgery: our experience].

Breast cancer is the most common tumour in Italy in the female population, counting for about 40000 new cases every year. The psychological aspects of breast mutilation and the social and economic implications are receiving increasing attention. Despite of the diffusion of screening programs to detect pre-clinical breast cancers, 30% of patients still undergo radical interventions. Therefore, many women present serious limitations of their social-life that can lead to severe depression since, in occidental countries, the biological function of the breast is less considered than its primary role of femininity and sexuality. The gold-standard is to conceal oncological radicality and aesthetic preservation. The Authors present their experience analysing the techniques employed.

Adult↗
PubMed2001

Expression of heme oxygenase in the oxygen-sensing regions of the rostral ventrolateral medulla.

Recently, unique regions in the rostral ventrolateral medulla (RVLM) have been found to be oxygen sensitive. However, the mechanism of sensing oxygen in these RVLM regions is unknown. Because heme oxygenase (HO) has been shown to be involved in the hypoxic responses of the carotid body and pulmonary artery, the aim of this study was to determine whether HO is present in the RVLM and whether expression of HO is altered by chronic hypoxia. Adult rats were exposed to hypoxia (10% O(2)) or normoxia (21% O(2)) for 10 days, and the mRNA for HO-1 and HO-2 was examined in the RVLM by using RT-PCR. Expression of HO-2 mRNA was seen in the RVLM of both control and hypoxic samples, whereas expression of HO-1 mRNA was only seen in the RVLM of hypoxic samples. HO-2 was immunocytochemically localized in brain sections (40 microm) to the C1 region and pre-Bötzinger complex of the RVLM. Together, these results indicate that HO-2 is present in the RVLM under control conditions and that HO-1 is induced in the RVLM during chronic hypoxia, consistent with a potential role for HO in the oxygen-sensing function of these cardiorespiratory RVLM regions.

Animals↗
PubMed2001

Abdominal aortic aneurysm resection following cholecystectomy and heart transplantation. Case report.

The case of a patient who underwent heart transplantation and cholecystectomy in 1993 and admitted for resection of abdominal aortic aneurysm in May 1997, is reported. About 25 minutes after unclamping the abdominal aorta the patient s blood pressure fell suddenly to 70/40 mmHg. In spite of vigorous fluid administration and infusion of Dopamine and Adrenaline the hemodynamic pattern returned to normal only 15 minutes later. The authors discuss the possible explanations of this behaviour (mesenteric traction syndrome, hypovolemia) and conclude that heart transplant patients are particularly affected by hypotension. Of paramount importance remains therefore the correct evaluation of adequate filling pressures which should be maintained slightly above normal range.

Aortic Aneurysm, Abdominal↗
PubMed2000

Focal polymicrogyria in mother and son.

This 9-year-old boy was admitted at the age of 2 with a diagnosis of congenital hemiparesis while the rest of physical and neurological examination was normal. His score in the Wechsler intelligence scale was 80. Right fronto-parietal cortical dysplasia with hemisphere atrophy was evident by computerized tomography scanning and magnetic resonance imaging. The latter, also disclosed abnormal thick cortex which was interpreted as polymicrogyria or pachygyria. Karyotype was normal. He had a hemifacial motor seizure at the age of 7. At the age of 8 frequent atonic or inhibitory seizures were presented. Asymmetric bilateral spike discharges with high voltage in the right hemisphere during the EEG recording were found. His mother, a 35-year-old woman (Full scale; Adult intelligence scale: 85) also had congenital hemiparesis. She never had seizures and her EEG was normal. Magnetic resonance imaging disclosed right fronto-parietal cortical dysplasia with ipsilateral hemisphere atrophy. Karyotype was normal. Our cases should be interpreted as a familial presentation of the anomaly, probably with autosomal-dominant transmission.

Adult↗
PubMed2000

Hypoxic excitation in neurons cultured from the rostral ventrolateral medulla of the neonatal rat.

Neurons within cardiorespiratory regions of the rostral ventrolateral medulla (RVLM) have been shown to be excited by local hypoxia. To determine the electrophysiological properties of these excitatory responses to hypoxia, we developed a primary dissociated cell culture system to examine the intrinsic response of RVLM neurons to hypoxia. Neonatal rat neurons plated on medullary astrocyte monolayers were studied using the whole cell perforated patch-clamp technique. Sodium cyanide (NaCN, 0.5-10 mM) was used, and membrane potential (V(m)), firing frequency, and input resistance were examined. In 11 of 19 neurons, NaCN produced a V(m) depolarization, an increase in firing frequency, and a decrease in input resistance, suggesting the opening of a cation channel. The hypoxic depolarization had a linear dose response and was dependent on baseline V(m), with a greater response at more hyperpolarized V(m). In 8 of 19 neurons, NaCN produced a V(m) hyperpolarization, decrease in firing frequency, and variable changes in input resistance. The V(m) hyperpolarization exhibited an all-or-none dose response and was independent of baseline V(m). These differential responses to NaCN were retained after synaptic blockade with low Ca(2+)-high Mg(2+) or TTX. Thus hypoxic excitation 1) is maintained in cell culture, 2) is an intrinsic response, and 3) is likely due to the increase in a cation current. These hypoxia-excited neurons are likely candidates to function as central oxygen sensors.

Animals↗
PubMed1999

Dehydroepiandrosterone sulfate levels in women. Relationships with age, body mass index and insulin levels.

Sex and age are the major determinants of serum levels of dehydroepiandrosterone sulfate (DHEA-S): they are about twice in men than in women and show a progressive reduction from the end of the puberty to aging in both sexes. It has been reported that DHEA-S levels are also negatively influenced by insulin. Moreover, DHEA-S levels reduction has been associated to increased risk for cardiovascular disease, which connotes hyperinsulinemic states, such as obesity. We have evaluated serum levels of DHEA-S and insulin as function of age and body mass index (BMI) in 376 adult women (age 18.1-89.6 yrs, median 42.2; BMI 15.7-57.8 kg/m2, median 32.7) by multiple regression and piecewise regression analysis. Insulin levels positively associated to BMI (p=0.000002) and DHEA-S levels negatively associated with age (p=0.000001). Considering the whole population, DHEA-S levels were related positively with BMI (p=0.0013) independently of age. DHEA-S were also directly related to insulin levels independently of age (p=0.042), but this association disappeared after correction for BMI. Piecewise regression analysis did not reveal a threshold level for the increase of BMI (p=0.0004). Interestingly, DHEA-S levels and BMI were positively associated before but not after menopause. Taking into account only obese population, (no.=143, age 18.7-67.3 yrs, mean 39.0, median 39.4) DHEA-S levels were again related negatively with age and positively with BMI, while were unrelated with waist to hip ratio (p=0.391). Our data show that increasing body mass and insulin secretion is not associated to DHEA-S reduction in women. This evidence suggests that DHEA-S is unlikely implicated in the pathogenesis of cardiovascular disease in obese women.

Adolescent↗
PubMed1999

Relationships between dehydroepiandrosterone-sulphate and anthropometric, metabolic and hormonal variables in a large cohort of obese women.

OBJECTIVE: The aim of the present study was to measure dehydroepiandrosterone-sulphate (DHEA-S) levels in obesity and assess the relationships between DHEA-S and anthropometric, metabolic and hormonal variables. SUBJECTS AND METHODS: We evaluated the serum DHEA-S levels in 217 obese but otherwise normal female subjects (age (mean +/- SEM): 39.4 +/- 0.9, range 18-67 years, body mass index (BMI) = 36.1 +/- 0.4, range 27.1-57.1 kg/m2). RESULTS: DHEA-S levels showed an age-dependent fall similar to that observed in normal women (n = 156, age 46.2 +/- 1.2, range 22-69 years, BMI < 25 kg/m2). Adjusting for age, obese women had mean DHEA-S levels higher than the control group (P < 0.02). In obese patients, DHEA-S levels were directly associated with serum testosterone, androstendione, IGF-I, fT3 levels and 24 h-urinary cortisol. On the other hand, DHEA-S levels were negatively associated with age, total cholesterol, triglycerides levels and systolic blood pressure. No correlation was found with BMI, waist:hip ratio, basal and post-OGTT insulin and glucose, free fatty acids, GH, PRL, fT4, TSH, SHBG levels or diastolic blood pressure. Multiple regression analysis indicated that in obese women, DHEA-S levels were associated negatively to age and positively to testosterone, androstendione and IGF-I levels and daily urinary cortisol. In a subgroup of 20 obese women, DHEA-S levels significantly (P < 0.001) fell after OGTT without any correlation with the insulin response. CONCLUSIONS: The present results show that dehydroepiandrosterone-sulphate levels are not reduced in obesity, being slightly increased, particularly in young adulthood. Dehydroepiandrosterone-sulphate levels are positively and independently associated with androgen, 24-h urinary cortisol and IGF-I levels but do not seem associated with insulin levels or cardiovascular risk indices.

Adolescent↗
PubMed1998

Hepatocellular carcinoma: comparison between liver transplantation, resective surgery, ethanol injection, and chemoembolization.

Between January 1989 and June 1997, 533 patients (423 male, 110 female, mean age 61 years, range 22-89 years) with hepatocellular carcinoma (HCC) were observed at our center. We report on 419 patients retrospectively compared for different treatments: liver transplantation (LT; 55 patients), resective surgery (RS; 41 patients), transarterial chemoembolization (TACE; 171 patients) and percutaneous ethanol injection (PEI; 152 patients). The 3- and 5-year actuarial survival rates were, respectively, 72% and 68% for LT, 64 and 44% for RS, 54 and 36% for PEI, and 32 and 22% for TACE. Survival curves were compared for sex, age, tumor characteristics, alphafetoprotein level, Child class, and etiology of cirrhosis. All patient-related characteristics examined (sex, age) are not significantly related to patient survival. Tumor-related variables and associated liver disease variables significantly conditioned survival in relation to different treatments. LT seems to be the treatment of choice for monofocal HCC less then 5 cm in diameter and in selected cases of plurifocal HCC.

Actuarial Analysis↗
PubMed1998

Autoimmune thyroid diseases and coeliac disease.

BACKGROUND: Coeliac disease may be associated with a wide variety of diseases of known or suspected immunological aetiology. OBJECTIVE: To screen for both (a) the prevalence of coeliac disease in adults with autoimmune thyroid diseases, and (b) thyroid impairment among adults with coeliac disease, as compared to sex- and age-matched controls. DESIGN: Prospective cohort study. SETTING: University teaching hospital. PATIENTS: A total of 152 consecutive adults with autoimmune thyroid diseases, 185 consecutive coeliac disease patients (53 newly diagnosed and 132 already on a gluten-free diet) and 170 sex- and age-matched controls. METHODS: Screening for coeliac disease was done by means of IgA anti-endomysium antibodies, detected by indirect immunofluorescence on monkey oesophagus. Patients with positive sera underwent duodenal biopsy for diagnostic confirmation. Thyroid function was assessed by measuring the levels of serum thyroid-stimulating hormone, free T3, free T4, thyroperoxidase and thyroid microsome antibodies. Autoimmune thyroid diseases were classified according to the American Thyroid Association guidelines. RESULTS: Anti-endomysium antibodies were positive in five of 152 autoimmune thyroid disease patients (3.3%) and coeliac disease was histologically confirmed in all: this prevalence is 10-fold higher than expected. Only one patient presented with gastrointestinal complaints, but iron deficiency was found in three and alterations at bone mineralometry in all. The overall prevalence of autoimmune thyroid diseases was significantly higher (38/185, 20.5%) in coeliac patients than in controls (19/170, 11.2%). The prevalence of both hypo- and hyperthyroidism was not different from that of controls, while the prevalence of autoimmune thyroid disease with euthyroidism was 13% in patients and 4.7% in controls. CONCLUSIONS: The association of coeliac disease with autoimmune thyroid disease is not surprising as they share common immunopathogenetic mechanisms. It is advisable to screen autoimmune thyroid disease patients for coeliac disease as there is an increased risk for gluten intolerance. In contrast, thyroid function assessment in coeliac disease patients is probably less justified, although the need for a strict clinical follow-up of those patients with euthyroidism and autoimmune thyroid disease, who could develop overt thyroid impairment, remains an open question.

Adolescent↗