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Biomedical subjects

L Serra

Publications and source records attributed to L Serra.

At least 19 recordsLinked to original sources
PubMed2000

Rapid evolution of a geographic cline in size in an introduced fly.

The introduction and rapid spread of Drosophila subobscura in the New World two decades ago provide an opportunity to determine the predictability and rate of evolution of a geographic cline. In ancestral Old World populations, wing length increases clinally with latitude. In North American populations, no wing length cline was detected one decade after the introduction. After two decades, however, a cline has evolved and largely converged on the ancestral cline. The rate of morphological evolution on a continental scale is very fast, relative even to rates measured within local populations. Nevertheless, different wing sections dominate the New versus Old World clines. Thus, the evolution of geographic variation in wing length has been predictable, but the means by which the cline is achieved is contingent.

Animals↗
PubMed2000

Planning and simulation of neurosurgery in a virtual reality environment.

OBJECTIVE: To report our experience with preoperative neurosurgical planning in our stereoscopic virtual reality environment for 21 patients with intra- and extra-axial brain tumors and vascular malformations. METHODS: A neurosurgical planning system called VIVIAN (Virtual Intracranial Visualization and Navigation) was developed for the Dextroscope, a virtual reality environment in which the operator reaches with both hands behind a mirror into a computer-generated stereoscopic three-dimensional (3-D) object and moves and manipulates the object in real time with natural 3-D hand movements. Patient-specific data sets from multiple imaging techniques (magnetic resonance imaging, magnetic resonance angiography, magnetic resonance venography, and computed tomography) were coregistered, fused, and displayed as a stereoscopic 3-D object. A suite of 3-D tools accessible inside the VIVIAN workspace enabled users to coregister data, perform segmentation, obtain measurements, and simulate intraoperative viewpoints and the removal of bone and soft tissue. RESULTS: VIVIAN was used to plan neurosurgical procedures primarily in difficult-to-access areas, such as the cranial base and the deep brain. The intraoperative and virtual reality 3-D scenarios correlated well. The VIVIAN system substantially contributed to surgical planning by 1) providing a quick and better understanding of intracranial anatomic and abnormal spatial relationships, 2) simulating the craniotomy and the required cranial base bone work, and 3) simulating intraoperative views. CONCLUSION: The VIVIAN system allows users to work with complex imaging data in a fast, comprehensive, and intuitive manner. The 3-D interaction of this virtual reality environment is essential to the efficient assembly of surgically relevant spatial information from the data derived from multiple imaging techniques. The usefulness of the system is highly dependent on the accurate coregistration of the data and the real-time speed of the interaction.

Adult↗
PubMed1999

Rising melanoma incidence in an Italian community from 1986 to 1997.

We examined the incidence of primary invasive melanoma in the municipality of Reggio Emilia, northern Italy, in the period from 1986 to 1997. We identified 169 cases, five of which were intraocular. After adjustment for confounders, the risk of having a thick melanoma (Breslow > or = 1 mm) did not decrease over time, except in older females. The age-standardized incidence of cutaneous melanoma during the entire study period was 7.57 in males and 11 in females; from 1986-1991 to 1992-1997, it rose from 5.04 to 10.04 cases/100,000 person-years in males and from 8.96 to 13.09 cases/100,000 person-years in females. In males, the increase in incidence was almost entirely confined to subjects aged 30 or more, suggesting a possible cohort effect. We noted rising age-standardized incidences over time both in males with thin tumours (Breslow < 1 mm) (from 2.05 to 4.38 cases/100,000 person-years) and thick tumours (from 2.73 to 5.51 cases/100,000 person-years), while in females the increase was limited to thin melanomas (from 3.14 to 6.93 cases/100,000 person-years), mainly due to an increase in the older age groups (50 69 years and > or =70 years). The increase in thick melanomas among males and the expected cohort effects suggests antecedent exposure to environmental risk factors.

Adolescent↗
PubMed1999

[Acetaminophen hepatotoxicity in an alcohol addicted student. Case report].

We report a 12 years old male with a history of excessive alcohol intake, that developed a severe liver failure after the use of acetaminophen in therapeutic doses. He presented with encephalopathy, jaundice, fever and an upper gastrointestinal bleeding. Serum aspartate aminotransferase values were 5,250 IU/L. The patient received supportive care and oral corticosteroids, remained severely compromised for 72 hours and had a good evolution thereafter. The association of acetaminophen use and excessive alcohol intake in a patient who developed an acute hepatic failure and the absence of serological evidence of hepatitis A or B viral infection, support the diagnosis of drug induced liver failure.

Acetaminophen↗
PubMed1999

Planning of skull base surgery in the virtual workbench: clinical experiences.

Based on the KRDL Virtual Workbench, we present a neurosurgical planning system called VIVIAN (Virtual Intracranial Visualization And Navigation). This VR environment allows for fast and intuitive interaction with three-dimensional multimodal (MRI, MRA, MRV, CT) patient specific data-sets. The user reaches behind a mirror into a 3D workspace where the 3D data is surrounded by interactive virtual tools-racks. Tumors, blood vessels, cranial nerves and surgically relevant parts of the brain are segmented by interactive control of density transfer-functions or by manual outlining and tracing tools. A neurosurgical procedure is planned by using various visualization and measurement tools and the system allows for the simulation of bone drilling and tissue removal. We have planned 16 cases which required tumor surgery at the cranial base. VIVIAN provided an efficient and comprehensive way to understand pre-operatively the complexity of anatomical and pathological relationships. The ideal craniotomy and the extent of the required skull base exposure could be specified accurately.

Computer Simulation↗
PubMed1999

An interface for precise and comfortable 3D work with volumetric medical datasets.

We have developed a 3D/2D paradigm of interaction that combines manipulation of precise 3D volumetric data with unambiguous widget interaction. Precise 3D interaction is ensured by a combination of resting the lower arms on an armrest and pivoting the hands around the wrist. Unambiguous 2D interaction is achieved by providing passive haptic feedback by means of a virtual control panel whose position coincides with the physical surfaces encasing the system. We have tested this interface with a neurosurgical planning application that has been clinically used for 17 skull-base cases at two local hospitals.

Computer Simulation↗
PubMed1998

Plasmodium vivax congenital malaria in a newborn of a Zairian immigrant.

We report a case of congenital malaria in a newborn whose mother is a native of Zaire now living in Italy. The baby developed remittent fever in the 3rd week of life with anaemia and hepatosplenomegaly. Malaria parasites found in blood smears and erroneously diagnosed initially as Plasmodium falciparum were subsequently recognized as Plasmodium vivax. On the basis of the first diagnosis, treatment with quinine chlorhydrate was successfully undertaken without significant side-effects. P. vivax parasites were also recovered a posteriori in blood smears of the mother who was febrile during the week of her delivery. This report suggests that symptomatic congenital malaria may be more common than is generally thought and should be suspected in non-malarious countries in febrile newborns born to mothers who have travelled in or immigrated from malaria-endemic areas.

Animals↗
PubMed1998

Chromosomal structure and recombination between inversions in Drosophila subobscura.

Drosophila subobscura is a species with rich chromosomal polymorphism. More than 45 arrangements have been described in the O chromosome. The recombination between them is an interesting topic, because many nonoverlapping arrangements are inherited together. In the analysis of recombination between the arrangements O7 and O3 + 4 + 8, out of 415 individuals observed none was found to be recombinant. The same result was obtained in the study of the recombination between the inversions O5 and O3 + 4, in which 437 individuals were analyzed. In this case a significant non equivalent segregation was found, the O5 chromosomes being more frequent than expected. This phenomenon could be explained by three hypotheses: a meiotic drive, a greater fitness of the individuals carrying this inversion and heterotic effect of a wild chromosome in combination with a chromosome from an inbred laboratory strain. If the second hypothesis is correct, it could explain why an inversion always associated with a lethal gene in American populations is not infrequent and presents a clinal distribution in the colonized areas. Furthermore, another inversion, O22, is very similar to O5. These two inversions can be distinguished only by careful observation. Although O22 and O5 are very similar they show different behavior in the wild, probably due to the combinations of genes included in them.

Animals↗
PubMed1998

Excess melanoma incidence in a cohort exposed to high levels of environmental selenium.

Epidemiological studies on the relation between selenium and human cancer have yielded strongly conflicting results. Prompted by the observation of a positive association between selenium intake and site-specific cancers, including melanoma, in a large cohort of nurses, we studied the 11-year melanoma incidence in an Italian cohort that consumed unusually high levels of inorganic selenium in tap water from 1975 to 1985. The setting was Reggio Emilia, an Italian municipality that provided a natural experiment relating to intake of high levels of inorganic selenium. We identified 2,065 individuals with high selenium exposure, who contributed a total of 20,179 person-years of follow-up, and we compared their experience with the 1,384,386 person-years of follow-up in the remaining population of Reggio Emilia. We included all cases of pathologically confirmed malignant melanoma, including intraocular melanoma, identified from the Reggio Emilia Hospital, the Bologna regional registry of hospital discharges, and the Milan National Cancer Institute. Eight cases of malignant melanoma occurred in the exposed cohort during the follow-up. Melanoma incidence was 3.9 times greater in the exposed than in the unexposed cohort (95% exact confidence limits, 1.8-7.4).

Adolescent↗
PubMed1998

[Audit of deaths due to cervical cancer in a health service of Santiago. A preliminary analysis].

BACKGROUND: Despite the epidemiological importance and the surveillance programs to detect cervix uterine cancer in Chile, its mortality continues to be high. AIM: To perform an audit of all deaths due to cervix uterine cancer, that occurred in a health service of Santiago during 1995. MATERIAL AND METHODS: The clinical records and pathological studies of 46 women, whose death certificates indicated cervix uterine cancer as the cause of death, were audited. RESULTS: In six women, the audit revealed that the cause of death was not a cervix uterine cancer, and they were discarded from further analyses. The higher mortality rate (36/100,000) occurred in women over 64 years old, those living in the poorest community and with less Papanicolaou vaginal smears coverage (La Pintana). The evolution prior to diagnosis was registered in only four women and was of less than one year. Most women consulted in advanced stages of the disease and only 48% were subjected to some sort of treatment (surgery, radiotherapy or chemotherapy). Mean survival was 3 years and mean age at death was 55.5 years old. There was a great lack of clinical and epidemiological information. In only 13 women information about previous Pap smears was registered. CONCLUSIONS: Audit of deaths should be an important component of preventive programs for cervix uterine cancer, and the coverage of Pap smears should be improved.

Adult↗
PubMed1997

Designing virtual selectors for surgeons.

Virtual Reality (VR) applications involve the use of manipulators or 'virtual tools' such as pointers, grippers and containers. Manipulation of such tools is a key feature of VR applications. Less attention has been directed towards designing the ways in which users select particular options or information, as they interact in the virtual world, by means of selectors. This is particularly important in the case of professional users, such as surgeons, who typically make heavy use of both selection and manipulation, switching frequently between the two in the course of their work. In this paper we describe the design and evaluation of two types of selector tool for use in medical VR applications. In this account, we provide details of the background behind the research and focus on design aspects of selector tools for use in a particular task context, that of medical surgery planning.

Adult↗
PubMed1997

The Brain Bench: virtual tools for stereotactic frame neurosurgery.

We present a suite of neurosurgery supporting tools developed around (i) the Virtual Workbench, a productive environment for the control of 3-D data, in which delicate work can be performed for hours on end without strain, and (ii) the Electronic Brain Atlas, integrating the major print brain atlases in day-to-day clinical use. We describe in detail the Brain Bench, a surgical planning system for stereotactic frame neurosurgery. Its objective is to prepare faster plans; have a better and more accurate choice of target points; improve the avoidance of sensitive structures; have fewer sub-optimal frame attachments and speedier, more effective planning and training. If validated by a clinical study now under way, this will improve medical efficacy and reduce costs.

Brain↗
PubMed1997

Diagnosis of sibling species of Drosophila involved in the colonization of North America by D. subobscura.

To determine the effects of the recent colonization of the west coast of North America by the Palaearctic species Drosophila subobscura on the dynamics of the Drosophila populations, the sibling species D. athabasca and D. azteca must be classified unambiguously. We have characterized these two species using three molecular techniques: allozymes, mtDNA and RAPDs. All three techniques allow the classification of any individual as belonging to either species. The study of five localities in northern California and southern Oregon show that the area of overlap is larger than previously described.

Animals↗
PubMed1997

Hemodynamic effects of plasma exchange in septic patients: preliminary report.

To assess the effects of plasma exchange on the hemodynamic performance of septic patients, we studied 12 septic patients (11 males and 1 female, age range 19-64, mean 39 +/- 17 years). After cardiovascular stabilization, plasma exchange was performed in the spontaneous mode via a femorofemoral arteriovenous shunt; during the treatment the infusion rate of cardiovascular drugs and the mechanical ventilation setting were not modified. Heart rate, pulmonary artery occlusion pressure, and peripheral vascular resistance did not change significantly. The stroke volume index increased significantly (from 49 +/- 9 to 60 +/- 9 ml/min/m2; p < 0.05) as well as the cardiac index (from 5.5 +/- 1.2 to 6.3 +/- 0.8 liters/min/m2, the oxygen delivery (from 785 +/- 166 to 872 +/- 118 ml/min/m2; p < 0.05), and the left ventricular stroke work index/pulmonary artery occlusion pressure ratio (from 4.03 +/- 1.92 to 5.07 +/- 2.54; p < 0.05). The oxygen consumption did not change. Four patients survived. In conclusion, in our patients plasma exchange was associated with an improvement in cardiac function, possibly due to the elimination of some sepsis mediator(s) with negative inotropic properties.

Adult↗
PubMed1995

Biosynthesis of C3 by human mesangial cells. Modulation by proinflammatory cytokines.

Deposits of complement (C) components are found in the glomeruli of patients with various glomerulonephritides without detectable immunoglobulins, thus suggesting a pathogenetic role of the locally produced proteins of this system. In the present study, we have examined human mesangial cells (HMC) for their ability to secrete C3. Three different cell lines were examined and all showed a basal production of C3, which was up-regulated following stimulation with IL-1 beta. IL-6 had no direct stimulatory effect on its own, but synergized with IL-1 to induce an increased production of C3 in the culture supernatant and its relative amount was confirmed by SDS-PAGE and immunoblot. Another agonist such as lipopolysaccharide was not able to induce any significant C3 synthesis. Analysis of C3 HMC gene expression, performed by both reverse transcription-polymerase chain reaction of isolated RNA and Northern blot, confirmed the parallel increase of the specific transcript under IL-1 beta and IL-1 beta + IL-6 stimulation. From these data we conclude that production of C3 in the mesangium could have a pathophysiologic relevance.

Base Sequence↗