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G Dalvit

Publications and source records attributed to G Dalvit.

9 recordsLinked to original sources
PubMed2005

Effect of alpha-tocopherol and ascorbic acid on bovine oocyte in vitro maturation.

In vitro culture results in higher oxygen concentrations than in vivo environments, leading to an increased level of reactive oxygen species (ROS) that cause lipid peroxidation of cellular membranes. Alpha-tocopherol (active form of vitamin E) is an antioxidant that protects mammalian cells against lipid peroxidation, which is regenerated by ascorbic acid. The aim of this study was to determine the effect of the addition of alpha-tocopherol and/or ascorbic acid to the maturation medium on bovine oocyte in vitro maturation (IVM) and subsequently on in vitro fertilization (IVF) and embryo development. Cumulus-oocyte complexes (COCs) were matured in Medium 199 (control), and with the addition of alpha-tocopherol and/or ascorbic acid. The concentration of alpha-tocopherol in COCs was determined by high-performance liquid chromatography (HPLC). IVF and in vitro culture (IVC) were carried out in modified synthetic oviductal fluid (mSOF). The quantity of alpha-tocopherol naturally present in COCs diminished by half during IVM (p < 0.05), although in the presence of ascorbic acid it remained constant. A greater amount of alpha-tocopherol was detected in COCs matured in medium supplemented with this antioxidant (p < 0.05), but the addition of alpha-tocopherol plus ascorbic acid maintained higher levels of alpha-tocopherol (p < 0.05). Significant differences were not observed in the percentages of nuclear maturation and fertilization among different treatments. The presence of alpha-tocopherol or ascorbic acid in the maturation medium failed to modify the percentage of blastocysts obtained, unlike the addition of both antioxidants when a significant decrease was observed (p < 0.05). Absorbic acid maintained the antioxidant capacity of the alpha-tocopherol incorporated to COC membranes during IVM. The active form of vitamin E during maturation impaired the acquisition of oocyte developmental competence.

Animals↗
PubMed2003

Involvement of enzymes of amino acid metabolism and tricarboxylic acid cycle in bovine oocyte maturation in vitro.

Few studies demonstrate at a biochemical level the metabolic profile of both cumulus cells and the oocyte during maturation. The aim of the present study was to investigate the differential participation of enzymatic activity in cumulus cells and in the oocyte during in vitro maturation (IVM) by studying the activity of enzymes involved in the control of amino acid metabolism, alanine aminotransferase (ALT) and aspartate aminotransferase (AST); and the tricarboxylic acid (TCA) cycle, isocitrate dehydrogenase (IDH) and malate dehydrogenase (MDH). No NAD-dependent isocitrate dehydrogenase (NAD-IDH) activity was recorded in cumulus-oocyte complexes (COCs). ALT, AST, NADP-dependent isocitrate dehydrogenase (NADP-IDH) and MDH enzymatic units remained constant in cumulus cells and oocytes during IVM. Specific activities increased in oocytes and decreased in cumulus cells as a result of IVM (P<0.05). Similar activity of both transaminases was detected in cumulus cells, unlike in the oocyte, in which activity of AST was 4.4 times greater than that of ALT (P<0.05). High NADP-IDH and MDH activity was detected in the oocyte. Addition of alanine, aspartate, isocitrate + NADP, oxaloacetate or malate + NAD to maturation media increased the percentage of denuded oocytes reaching maturation (P<0.05), in contrast to COCs in which differences were not observed by addition of these substrates and co-enzymes. The activity of studied enzymes and the use of oxidative substrates denotes a major participation of transaminations and the TCA cycle in the process of gamete maturation. The oocyte thus seems versatile in the use of several oxidative substrates depending on the redox state.

Alanine Transaminase↗
PubMed2002

Activity of key enzymes involved in glucose and triglyceride catabolism during bovine oocyte maturation in vitro.

Little is known about the metabolic profile of cumulus-oocyte complexes (COCs) during maturation. The aim of this study was to determine the differential participation of enzymatic activity in cumulus cells and the oocyte during in vitro maturation of bovine oocytes, by measuring the activity of key enzymes involved in the regulation of glycolysis (phosphofructokinase), the pentose phosphate pathway (glucose-6-phosphate dehydrogenase) and lipolysis (lipase). COCs were matured in medium 199 plus 10% (v/v) steer serum for 22-24 h at 39 degrees C in 5% CO(2):95% humidified air. Phosphofructokinase, glucose-6-phosphate dehydrogenase and lipase activities were measured in immature and in vitro matured COCs, denuded oocytes and cumulus cells, respectively. Phosphofructokinase and glucose-6-phosphate dehydrogenase activities (enzymatic units) remained constant during in vitro maturation of COCs, but there was a significant decrease in lipase activity (units) (P < 0.05), as activity in cumulus cells decreased significantly (P < 0.05). For the three enzymes studied, enzyme activity (units) remained unchanged in the oocyte during in vitro maturation. Specific activity increased in the oocyte (P < 0.05) and decreased in cumulus cells as a result of maturation (P < 0.05). In cumulus cells, phosphofructokinase was the most abundant of the three enzymes followed by glucose-6-phosphate dehydrogenase and then lipase (P < 0.05), whereas in the denuded oocyte this order was reversed (P < 0.05). Thus, the metabolism of cumulus cells is adapted to control the flow of metabolites toward the oocyte, which maintains its enzymatic activity even when dissociated from cumulus cells during maturation. The high activity of phosphofructokinase in cumulus cells indicates that glucose is metabolized mainly via the glycolytic pathway in these cells. The greater relative activity of glucose-6-phosphate dehydrogenase recorded in the oocyte indicates that glucose uptake could be directed mainly toward the pentose phosphate pathway. The marked lipolytic activity concentrated in the oocyte indicates an active participation in lipid catabolism during maturation.

Animals↗
PubMed1996

[Current didactic concepts--243 participants evaluate Rheuma 2000].

The Swiss League against Rheumatic diseases in collaboration with rheumatologists organized a special educational program for general practitioners. An evaluation questionnaire was filled in by 238 of the 243 participants. With an average value of 4.57 points out of possible 5.0 the new educational concept was very successful. The interactive learning process in small groups seems to be a good alternative to formal lectures.

Education, Medical, Continuing↗
PubMed1996

A prospective controlled study of low back school in the general population.

There are no data on the efficacy of a back school in primary prevention of back pain in the general population or on the characteristics of the population who volunteers. After announcement in the local press, 494 healthy adults volunteered and paid for a back school course in Switzerland. A total of 371 controls were matched for sex, age, profession, nationality and back pain. A statistically significant decrease in numbers of doctor's visits was found by the participants during the following 6 months compared with the controls. However, there were no significant between-group difference in the four remaining parameters (presence and intensity of back pain, drug intake and sick leave). Three-quarters of participants changed their attitudes after the back school. Volunteering for a back pain prevention programme was associated with the presence of back pain problems. Reasons for volunteering are further discussed. Overall, the results of this study showed that a back school for the general population may not solve the problem of low back pain, but improves self-help in a subgroup of the population.

Adult↗
PubMed1984

[The problems of rheumatic patients].

Seen by the Rheumatism Leagues the problems of rheumatism patients are shown in the analyzes given by the annual reports. Felt by the sufferers themselves they can be found in analyzing the entries of the Stene-Prize of EULAR. Main problems are pain and impairment. Loneliness ranges last.

Adult↗