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Biomedical subjects

P Volpe

Publications and source records attributed to P Volpe.

At least 181 records · Page 10Linked to original sources
PubMedDate not supplied

Repair-modification and evolution of the eukaryotic genome organization.

For a complete reconstruction of the damaged unmethylated islands, in theory, the conventional excision-repair is sufficient. For a complete reconstruction of the damaged methylated domains, a coupling has to take place involving the excision-repair (able to reestablish their ATGC-language) plus the DNA-methylase (able to reestablish their modified ATGC5mC-language). This coupling, defined as "repair-modification," is essentially functioning during the S-phase, because the DNA-polymerase beta (pol beta) is active during the whole cell cycle, whereas the DNA-methylase (met) is active in S and appears to be repressed or inactive during the major part of G1 and during the phases G2 and M. Consequently, after damage, some silent genes might become expressed during these phases, if it is true that DNA methylation is inversely proportional to transcription. Repair-modification should, therefore, exert a continuous differential pressure on evolution of given parts of the genome, when they are methylated to a different extent. According to Darwinian concepts, repair-modification would lead to a high variability, especially of uncoding DNA sequences (if hypermethylated), whereas on the basis of this variability, selection might favor transposition of specific regulatory elements into given transcriptional units. In these, the conservative nature of the coding elements (if unmethylated) would obviously be ensured by the conventional excision-repair.

Animals↗
PubMedDate not supplied

Inositol 1,4,5-trisphosphate receptor and ryanodine receptor in the aging brain of Wistar rats.

Intracellular Ca2+ release channels are key players in the regulation of Ca2+ homeostasis. In the present study, we investigated the age-related changes of inositol 1,4,5-trisphosphate (IP3) receptor/Ca2+ release channel and ryanodine receptor/Ca2+ release channel in microsomes derived from either cerebellum or cerebrum cortex from male Wistar rats. A significant reduction (about 50%) in density of IP3 receptor/Ca2+ release channels was observed in cerebrum cortex, only, in 8- and 28-month old rats, whereas density and Kd of ryanodine binding sites were unaffected in both cerebellum and cerebrum microsomes. These findings, along with impairment of Ca(2+)-dependent protein kinase C phosphorylation of endogeneous substrates, point to coordinate, quantitative alterations of both targets of phosphoinositide metabolism, i.e., PKC and IP3 receptor, in the cerebrum cortex at least. The relevance of the present findings is discussed in relation to reported changes of neuronal Ca2+ homeostasis during aging.

Aging↗
PubMedDate not supplied

Inositol 1,4,5-trisphosphate induces calcium release from sarcoplasmic reticulum of skeletal muscle.

The sarcoplasmic reticulum of skeletal muscle is a specialized form of endoplasmic reticulum that controls myoplasmic calcium concentration and, therefore, the contraction-relaxation cycle. Ultrastructural studies have shown that the sarcoplasmic reticulum is a continuous but heterogeneous membranous network composed of longitudinal tubules that surround myofibrils and terminal cisternae. These cisternae are junctionally associated, via bridging structures called 'feet', with sarcolemmal invaginations (the transverse tubules) to form the triadic junction. Following transverse tubule depolarization, a signal, transmitted along the triadic junction, triggers Ca2+ release from terminal cisternae, but the mechanism of this coupling is still unknown. Inositol 1,4,5-trisphosphate (Ins(1,4,5)P3) has recently been shown to mobilize Ca2+ from intracellular stores, referable to endoplasmic reticulum, in a variety of cell types (see ref. 8 for review), including smooth muscle cells of the porcine coronary artery and canine cardiac muscle cells. Here we show that Ins(1,4,5)P3 releases Ca2+ from isolated, purified sarcoplasmic reticulum fractions of rabbit fast-twitch skeletal muscle, the effect being more pronounced on a fraction of terminal cisternae that contains morphologically intact feet structures; and elicits isometric force development in chemically skinned muscle fibres.

Animals↗
PubMedDate not supplied

[Training of surgeons in laparoscopic surgery of the digestive system. Experience in 1,818 interventions without accidents and mortality].

UNLABELLED: Since the beginning or laparoscopic surgery on University of Sao Paulo Medical School Clinics Hospital, the Digestive Surgery Division established an educational program for surgeons of the alimentary tract. PURPOSE: The course structure includes the information on medical school, extension in laparoscopic surgery league, and surgical formation during the residence, mainly in the fourth year, with a three months period in the Laparoscopic Surgery Unit. METHOD: This model of surgical formation is certainly responsible for the excellent results obtained. RESULTS: An example is the performing of 1818 cholecystectomies in the Laparoscopic Surgery Unit from 1990 till 1998, with 0.9% convertion, and no mortality. The absence of operative accidents or complications give support to the orientation assumed in our Division. CONCLUSION: In a university hospital there is the necessity of professional formation in a well structured program, with humanistic and technical education, in a large period of rotation, but with a solid information and practical structure.

Cholecystectomy, Laparoscopic↗
PubMedDate not supplied

Extrahepatic bile ducts injury: a report on 14 cases.

Traumatic injuries of the extrahepatic biliary tract are infrequent, occurring in approximately 0.5% of all patients with blunt and penetrating abdominal trauma. The incidence of this injury due to blunt abdominal trauma is rare. This study reviewed patients with injuries of the extrahepatic biliary tract due to abdominal trauma over a 6-year period to determine the incidence, trauma scores, associated injuries, surgical treatment performed, complications and mortality rate. We report our experience with 14 patients with extrahepatic biliary tract trauma. A review of the literature and the discussion about the management are presented.

Abdominal Injuries↗
PubMedDate not supplied

[Synchronous esophageal and stomach neoplasm: importance of diagnosis and treatment].

The association of esophageal and gastric cancer has been described because of the better technology in methods for diagnosis. In surgery for esophageal cancer, a gastric tube is often prepared to provide a new route for oral ingestion. Although patients with simultaneous esophageal cancer and gastric cancer have been reported, it is often difficult to diagnose the coexistence of gastric cancer preoperatively due to the presence of esophageal stenosis. In this paper we report on one case of the rare combination of squamous cell cancer of the esophagus and simultaneous adenocarcinoma of the stomach.

Adenocarcinoma, Mucinous↗
PubMedDate not supplied

[Esophagectomy using videosurgery].

This is a report of 10 cases of esophagetomy by videosurgery. Five patients had esophageal carcinoma and five had achalasia. The patients who had neoplasia were submitted to thoracoscopic, laparoscopic and cervicotomy and the others who had benign pathology were submitted to laparoscopic with transdiafragmatic approach and cervicotomy. The evolution was very satisfactory but there were complications that had no relation with the method. The follow up is being made and we have no sure about real results.

Adult↗
PubMedDate not supplied

Gallbladder injuries due to blunt abdominal trauma: report on five cases and review of the literature.

Gallbladder lesions by blunt abdominal trauma are rare, due to the organ's anatomical particularities. Diagnosis is difficult, and it generally occurs during surgery. The trauma is usually associated with other lesions and is related to very serious traumas or to deceleration. Due to the scarcity of publications on this topic and to its reduced incidence, we present here a report of five patients who had suffered blunt abdominal trauma with gallbladder lesion and who were attended at the General Hospital (of the University of São Paulo Medical School) Emergency Service between 1986 and 1991. Furthermore, we analyze the incidence of this trauma, presence of associated lesion, treatment, morbidity and mortality of the patients, as well as a review of the literature.

Abdominal Injuries↗