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L Serra

Publications and source records attributed to L Serra.

At least 37 records · Page 2Linked to original sources
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↗
PubMed1995

Colonization of the Americas by Drosophila subobscura: lethal-gene allelism and association with chromosomal arrangements.

Drosophila subobscura is a Palearctic species that has recently colonized the Americas. It was first found in 1978 in Puerto Montt, Chile, and in 1982 in Port Townsend, WA. The colonization and rapid expansion of the species in western South and North America provides distinctive opportunities for investigating the process of evolution in action. The inversion polymorphism in the O chromosome from populations of central California and northern Washington, separated by 1300 km, corresponds to a previously observed latitudinal cline, also observed in Europe. Recessive lethal genes are not randomly distributed among the chromosomal arrangements. The incidence of lethal allelism is high, yielding unrealistically low estimates of the effective size of these populations (on the order of 1000 individuals). The high incidence of lethal allelism is likely to be a consequence of the low number of the American colonizers (on the order of 10-100 individuals), but the persistence of the allelism over several years suggests that some lethal-carrying chromosomes may be heterotic owing to shared associations between lethal and other genes.

Alleles↗
PubMed1995

On the origin of the O5 chromosomal inversion in American populations of Drosophila subobscura.

D. subobscura, a typically Palearctic species, has recently colonized the American continent. The population from which the colonization started is still unknown. A complete association between a lethal gene and the O5 chromosomal inversion has been detected in the colonizing populations; this association could be used to ascertain the origin of the colonization. In the present study, three hypotheses on the origin of this association are analyzed and their probabilities are calculated. According to the first hypothesis an O5 chromosome carrying a lethal gene would have been included in the sample from which the colonization started, thus originating the association found in the American populations. The second hypothesis assumes that, at the beginning of the colonization, the association between the O5 inversion and a lethal gene would have been formed from an Ost chromosome carrying a lethal gene, on which a new O5 (or similar) inversion arose. In the last hypothesis, the association between the O5 inversion and the lethal gene would have originated at the beginning of the colonization from a lethal-free O5 chromosome, in which a lethal gene arose due to mutation.

Animals↗