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L Massa

Publications and source records attributed to L Massa.

18 recordsLinked to original sources
PubMed2003

Pancreatic duodenal homeobox-1 and islet neogenesis-associated protein: a possible combined marker of activateable pancreatic cell precursors.

The aim of this work was to study the possible relationship between pancreatic duodenal homeobox-1 (Pdx-1) and islet neogenesis-associated protein (INGAP) during induced islet neogenesis. Pregnant hamsters were fed with (S) and without (C) sucrose, and glycemia, insulin secretion in vitro, and pancreas immunomorphometric parameters were measured in their 7-day-old offspring. S offspring had significantly lower glycemic levels than C animals. Insulin release in response to increasing glucose concentrations in the incubation medium (2-16 mM glucose) did not increase in pancreata from either C or S offspring. However, pancreata from S offspring released more insulin than those from C animals. In S offspring, beta-cell mass, beta-cell replication rate and islet neogenesis increased significantly, with a simultaneous decrease in beta-cell apoptotic rate. INGAP- and Pdx-1-positive cell mass also increased in the islets and among acinar and duct cells. We found two subpopulations of Pdx-1 cells: INGAP-positive and INGAP-negative. Pdx-1/INGAP-positive cells did not stain with insulin, glucagon, somatostatin, pancreatic polypeptide, or neurogenin 3 antibodies. The increment of Pdx-1/INGAP-positive cells represented the major contribution to the Pdx-1 cell mass increase. Such increments varied among pancreas subsectors: ductal>insular>extrainsular. Our results suggested that INGAP participates in the regulation of islet neogenesis, and Pdx-1/INGAP-positive cells represent a new stem cell subpopulation at an early stage of development, highly activateable in neogenesis.

Animals↗
PubMed2001

Quantal density functional theory of excited states.

We explain by quantal density functional theory the physics of mapping from any bound nondegenerate excited state of Schrödinger theory to an S system of noninteracting fermions with equivalent density and energy. The S system may be in a ground or excited state. In either case, the highest occupied eigenvalue is the negative of the ionization potential. We demonstrate this physics with examples. The theory further provides a new framework for calculations of atomic excited states including multiplet structure.

Journal Article↗
PubMed2001

Effects of plant-derived naphthoquinones on the growth of Pleurotus sajor-caju and degradation of the compounds by fungal cultures.

The growth of the white-rot basidiomycete Pleurotus sajor-caju in malt-agar plates was inhibited by three naturally occurring, plant-derived naphthoquinones: juglone, lawsone, and plumbagin. The latter two compounds exerted the most potent antifungal activity, and lawsone killed the mycelium at concentrations higher than 200 ppm. Plates containing juglone and lawsone presented large decolorized areas extending from area of fungal growth, suggesting an extracellular enzymatic degradation of these quinones. Screening of culture plates for extracellular enzymatic activities revealed the presence of both laccase and veratryl alcohol oxidase in most plates, the diffusion of both enzymes matching the decolorized area. In agitated cultures, the presence of juglone was found to stimulate the production of veratryl alcohol oxidase in a significant manner. This is the first time degradation of plant derived naphthoquinones by a white-rot fungus is reported.

Biodegradation, Environmental↗
PubMed2001

[Changes in medical treatment of heart failure in the light of large clinical trials].

In the last years, the treatment of heart failure has radically changed, as has knowledge of this complex and heterogeneous clinical syndrome. This is largely due to the results of several multicenter clinical trials, which have been undertaken since the late 80's. These trials have not only contributed to the elaboration of present-day treatment protocols, but also to a better understanding of the pathophysiologic mechanisms involved in heart failure. In the past, heart failure was generally interpreted on the basis of pathophysiologic models according to which hemodynamic abnormalities played a very important role in determining the clinical presentation and evolution of the disease. This led to the use of digitalis, diuretics, inotropic drugs and vasodilators for the treatment of heart failure. More recently, improved knowledge of the pathophysiologic mechanisms involved in the progression of this disease has highlighted the central role and the complexity of various neurohormonal mechanisms. Antagonism of these systems has proved to be the only strategy which favorably modifies the natural history of heart failure. The proved effectiveness of ACE-inhibitors and particularly of beta-blockers in patients with heart failure and left ventricular systolic dysfunction was the most convincing demonstration of the validity of this model. However, the evolution and updating of the guidelines on the treatment of heart failure should only be considered as the first step in the development of strategies aimed at extending these principles to daily clinical practice and in particular to the real patient who is different from patients typically enrolled in heart failure trials. Moreover, the development of new effective models for the management of the ever-growing number of patients with heart failure is of utmost urgency.

Clinical Trials as Topic↗
PubMed2000

Possible relationship between changes in islet neogenesis and islet neogenesis-associated protein-positive cell mass induced by sucrose administration to normal hamsters.

The possible relationship between changes in islet cell mass and in islet neogenesis-associated protein (INGAP)-cell mass induced by sucrose administration to normal hamsters was investigated. Normal hamsters were given sucrose (10% in drinking water) for 5 (S8) or 21 (S24) weeks and compared with control (C) fed hamsters. Serum glucose and insulin levels were measured and quantitative immunocytochemistry of the endocrine pancreas was performed. Serum glucose levels were comparable among the groups, while insulin levels were higher in S hamsters. There was a significant increase in beta-cell mass (P<0.02) and in beta-cell 5-bromo-2'-deoxyuridine index (P<0.01), and a significant decrease in islet volume (P<0.01) only in S8 vs C8 hamsters. Cytokeratin (CK)-labelled cells were detected only in S8 hamsters. INGAP-positive cell mass was significantly larger only in S8 vs C8 hamsters. Endocrine INGAP-positive cells were located at the islet periphery ( approximately 96%), spread within the exocrine pancreas ( approximately 3%), and in ductal cells (<1%) in all groups. INGAP positivity and glucagon co-localization varied according to topographic location and type of treatment. In C8 hamsters, 49.1+/-6. 9% cells were INGAP- and glucagon-positive in the islets, while this percentage decreased by almost half in endocrine extra-insular and ductal cells. In S8 animals, co-expression increased in endocrine extra-insular cells to 36.3+/-9.5%, with similar figures in the islets, decreasing to 19.7+/-6.9% in ductal cells. INGAP-positive cells located at the islet periphery also co-expressed CK. In conclusion, a significant increase of INGAP-positive cell mass was only observed at 8 weeks when neogenesis was present, suggesting that this peptide might participate in the control of islet neogenesis. Thus, INGAP could be a potentially useful tool to treat conditions in which there is a decrease in beta-cell mass.

Animals↗
PubMed1997

Postnatal sequential changes in islet morphology and insulin secretion of normal hamsters.

We have studied the postnatal development of the endocrine pancreas from normal female Syrian golden hamsters 1, 8, and 24 weeks of age. The observations were made by (a) analysis of insulin secretion in response to glucose using isolated pancreatic islets and (b) identification and quantitation of insulin-, glucagon-, somatostatin-, and pancreatic polypeptide-secreting cells. Glucose-induced insulin secretion showed typical dose-response curves. However, whereas in 24-week-old animals maximal secretion was already present with 8 mM glucose, in younger hamsters such a response was attained only with 20 mM glucose. The volume density of the endocrine pancreas and the number of islets were increased in 1-week-old hamsters compared to the older animals. The islet volume average in 8-week-old hamsters was almost three times higher than that measured in 1-week-old animals. However, the proportion and size of each cell type in the islets did not present significant differences among the groups studied. Our results show that, in hamsters, the endocrine pancreas reaches the adult general characteristics late after birth. Furthermore, the definite morphological pattern is attained far earlier than the secretory response. These observations provide basic information for further studies regarding the mechanisms and factors that control both the growth and the differentiation of endocrine cell populations as well as glucose-induced insulin secretion in a simple experimental model.

Age Factors↗
PubMed1997

Insulin-like growth factor binding proteins from adult-hamster pancreatic islets: influence of glucose concentration.

This study investigated the effect of glucose on insulin-like growth factor binding proteins (IGFBPs) in islets isolated from pancreas of adult hamsters and compared the response pattern with that of their serum IGFBPs. Serum samples and islets were obtained from adult normal male hamsters, and IGF-binding capacity was measured in aliquots of serum, sonicated islets, or conditioned medium using either 125I-hIGF-I or -II. IGFBPs were characterized in these samples by the ligand-blotting technique, and insulin was measured in conditioned medium by radioimmunoassay. Three IGFBP fractions were identified in serum, with relative molecular weights of 38, 30-33, and 24 kDa, while only two fractions of 30-33 and 24 kDa were identified in islets or in their conditioned medium. Islets cultured with 2 or 16 mM glucose for 48 h released more insulin in the presence of the higher glucose concentration. The binding capacity measured in the islet suspension or conditioned medium increased as a function of glucose concentration in the incubation medium. The IGFBPs present both in islets and conditioned medium had a 3- to 4-fold higher apparent affinity for IGF-II than IGF-I. The higher glucose concentration increased the intensity of the two IGFBP bands identified in the islet suspension by 2- to 3-fold. Our data show that two low-molecular-weight IGFBPs were released from adult hamster pancreatic islets, with a different distribution pattern from that of hamster serum, and that the amount of IGFBPs released by islets depended on the glucose concentration in the culture medium. Though not conclusive, these data suggest that IGFBPs may play a regulatory role in B-cell turnover in adult islets as they do in foetal islets.

Animals↗
PubMed1994

[Activities at the polyvalent intensive care unit of the Santo António dos Capuchos Hospital].

The authors present an audit to a multidisciplinary Intensive Care Unit of a tertiary Hospital (HSAC) over its first year (1/07/1991-30/06/1992). The total study population numbered 282 patients, 52.5% admitted from the emergency room. The mean age was 57.91 +/- 18.16 years. Cardiovascular failure (39%) and respiratory failure (35%) were the main diagnostic categories for admission; 50.7% of the patients needed mechanical ventilation, 44% echocardiogram, 13.5% bronchoscopy and 10.3% hemodynamic evaluation with Swan-Ganz catheter. These are patients with high mean values of severity scoring systems, ICU mortality (27%) and Hospital mortality (37.6%). APACHE II, SAPS I and TISS on day one of admission and maximum value over a 24 hour period of two multiple organ failure systems-MOF and OSF were validated in this population and were good outcome predictors.

Adolescent↗
PubMed1979

[Prognostic elements in bronchial carcinoma].

In spite of improvements in diagnosis and treatment, the fatal prognosis of lung cancer has persisted over the course of 25 years in a series of nearly 4000 patients. Only 30% (1149 cases) were operable, and on 23% of those resected (i.e. 7% of the total) survived for 5 years. An assessment is made of the relationship between survival and sex, age, tumour size and site, radiological picture, stage of invasiveness, type of surgery and degree of radicality, histological picture, and number of circulating lymphocytes. Age, sex and the type of resection (lobectomy or pneumonectomy) had no relation to prognosis. Palliative surgery was always associated with a fatal prognosis, as were cases with invasion of the chest wall, or, more particularly, with oat cell cancers. The outlook was more favourable in cases where radical treatment was given, in cases of squamous cancer, as opposed to other histological types, in those in stage 1 (Am. Joint Committee classification), and those with greater than 2000/mm3 lymphocytes--especially in adenocarcinomas.

Humans↗
PubMedDate not supplied

Changes induced by sucrose administration upon the morphology and function of pancreatic islets in the normal hamster.

BACKGROUND: This report documents sequential changes in islet morphology (cell replication and islet neogenesis) and glucose-induced insulin secretion in young normal male Syrian hamsters. METHODS: Three-week-old animals received a control standard commercial diet or this diet supplemented with sucrose--10% (w/v) solution in drinking water, a treatment that stimulated pancreatic growth and function--for 5 (C5/S5) or 21 (C21/S21) weeks. Insulin secretion and content were measured in isolated islets, while several biochemical parameters were assessed in serum. Different morphological features were analysed in the endocrine pancreas by quantitative immunocytochemistry. RESULTS: Serum glucose, triglycerides and total cholesterol levels were comparable among the groups, whereas serum- and pancreatic-insulin levels were higher in the S hamsters. Islets from S21 hamsters released more insulin than those from C21 animals at all glucose concentrations tested. The volume densities of the total endocrine pancreas (1.9 +/- 0.2 vs 1.2 +/- 0.2; p < 0.02) of the beta-cell subpopulation, the islet number per unit area (2.4 +/- 0.1 vs 1.2 +/- 0.1; p < 0.0004) and the beta-cell mass (4.2 +/- 0.5 vs 2.3 +/- 0.5; p < 0.01) were significantly higher in S5 vs C5 animals. Conversely, the islet volume and the number of beta cells/islets were significantly smaller in S5 than in C5 animals. The beta-cell replication rate in S5 hamsters was 10-fold that of C5 animals. All these parameters had comparable values in S21 and C21 animals. We detected cytokeratin-labelled cells located at the islet periphery (in alpha cells) and among the ductular cells, only in the S5 hamsters. CONCLUSIONS: Sucrose administration to young hamsters causes time-dependent pancreatic modifications, with morphological changes (increase in islet- and in beta-cell mass with incremented beta-cell replication rate and evidence of islet neogenesis) occurring at 5 weeks and insulin secretion (increase in insulin sensitivity to glucose) being mainly affected at 21 weeks. This experimental model could prove useful for studying the mechanisms underlying the control of islet-cell population distribution and for developing new strategies in preventing cell damage.

Animals↗