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Biomedical subjects

M Vicente

Publications and source records attributed to M Vicente.

At least 37 records · Page 2Linked to original sources
PubMed1998

Endoscopic harvesting of radial artery graft for coronary artery bypass.

The radial artery is used frequently in cardiac revascularization and requires an average 23-cm forearm incision. With proper instrumentation (Tsukuba-West Virginia Endoscopic Radial Artery: TW-ERA series, Takumi Cardio Co., Chiba, Japan), the radial artery can be harvested utilizing two small transverse incisions. The authors report six cases of endoscopic harvest of a radial artery graft. Length of the endoscopic incision is 2 cm proximally and 3 cm distally. Operation time and tourniquet times were approximately 80 to 120 minutes. No complications such as hematomas, nerve damage, or delay in healing were observed at the donor sites. Plastic surgeons, with their expertise in radial forearm flaps, hand surgery, and subcutaneous endoscopic techniques, can contribute greatly to the minimally invasive harvesting of the radial artery, preventing associated morbidity and improving the aesthetic and functional outcome of the donor site.

Adult↗
PubMed1998

Localization of cell division protein FtsQ by immunofluorescence microscopy in dividing and nondividing cells of Escherichia coli.

The localization of cell division protein FtsQ in Escherichia coli wild-type cells was studied by immunofluorescence microscopy with specific monoclonal antibodies. FtsQ could be localized to the division site in constricting cells. FtsQ could also localize to the division site in ftsQ1(Ts) cells grown at the permissive temperature. A hybrid protein in which the cytoplasmic domain and the transmembrane domain were derived from the gamma form of penicillin-binding protein 1B and the periplasmic domain was derived from FtsQ was also able to localize to the division site. This result indicates that the periplasmic domain of FtsQ determines the localization of FtsQ, as has also been concluded by others for the periplasmic domain of FtsN. Noncentral FtsQ foci were found in the area of the cell where the nucleoid resides and were therefore assumed to represent sites where the FtsQ protein is synthesized and simultaneously inserted into the cytoplasmic membrane.

Antibodies, Monoclonal↗
PubMed1998

[Laboratory surveillance of measles. Chile, 1992-1995].

BACKGROUND: The first massive national measles vaccination campaign in Chile was done in 1992. Since then a laboratory surveillance of the disease has been undertaken at the Instituto de Salud Pública. AIM: To report the results of laboratory surveillance of measles between 1992 and 1995. MATERIAL AND METHODS: Paired serum samples from suspected cases of measles were received at the Institute. Measles specific IgG was determined with indirect immunofluorescence methods. IgG and IgM immunoenzymatic methods were used as complementary techniques, and rubella infections were ruled out by hemmaglutination inhibition tests. RESULTS: Sera from 1087 presumptive cases (489 in 1992, 196 in 1993, 180 in 1994 and 222 in 1995) were analyzed. Only two cases of wild imported measles were confirmed, one in Arica in 1992 and the other in Santiago in 1993. Five additional post vaccine cases were detected. Eighty eight percent of samples in 1992 and 75% in 1994 were seropositive. A high percentage of cases were confirmed as rubella (55% in 1992 and 19% in 1994). CONCLUSIONS: Absence of wild measles virus circulation in Chile from 1992 to 1995 emphasizes the importance of laboratory surveillance of the disease.

Child↗
PubMed1997

Computer-based desktop system for surgical videotape editing.

BACKGROUND: The educational role of surgical video presentations should be optimized by linking surgical images to graphic evaluation of indications, techniques, and results. We describe a PC-based video production system for personal editing of surgical tapes, according to the objectives of each presentation. METHODS: The hardware requirement is a personal computer (100 MHz processor, 1-Gb hard disk, 16 Mb RAM) with a PC-to-TV/video transfer card plugged into a slot. Computer-generated numerical data, texts, and graphics are transformed into analog signals displayed on TV/video. A Genlock interface (a special interface card) synchronizes digital and analog signals, to overlay surgical images to electronic illustrations. The presentation is stored as digital information or recorded on a tape. RESULTS: The proliferation of multimedia tools is leading us to adapt presentations to the objectives of lectures and to integrate conceptual analyses with dynamic image-based information. We describe a system that handles both digital and analog signals, production being recorded on a tape. Movies may be managed in a digital environment, with either an "on-line" or "off-line" approach. System requirements are high, but handling a single device optimizes editing without incurring such complexity that management becomes impractical to surgeons. CONCLUSIONS: Our experience suggests that computerized editing allows linking surgical scientific and didactic messages on a single communication medium, either a videotape or a CD-ROM.

Analog-Digital Conversion↗
PubMed1997

Contribution of individual promoters in the ddlB-ftsZ region to the transcription of the essential cell-division gene ftsZ in Escherichia coli.

The essential cell-division gene ftsZ is transcribed in Escherichia coli from at least six promoters found within the coding regions of the upstream ddlB, ftsQ, and ftsA genes. The contribution of each one to the final yield of ftsZ transcription has been estimated using transcriptional lacZ fusions. The most proximal promoter, ftsZ2p, contributes less than 5% of the total transcription from the region that reaches ftsZ. The ftsZ4p and ftsZ3p promoters, both located inside ftsA, produce almost 37% of the transcription. An ftsAp promoter within the ftsQ gene yields nearly 12% of total transcription from the region. A large proportion of transcription (approximately 46%) derives from promoters ftsQ2p and ftsQ1p, which are located inside the upstream ddlB gene. Thus, the ftsQAZ genes are to a large extent transcribed as a polycistronic mRNA. However, we find that the ftsZ proximal region is necessary for full expression, which is in agreement with a recent report that mRNA cleavage by RNase E at the end of the ftsA cistron has a significant role in the contol of ftsZ expression.

Bacterial Proteins↗
PubMed1996

[Teachers' attitudes toward smoking prevention at schools].

Teenage smoking continues to present a significant public health problem. Children begin to smoke in elementary and middle school, although consumption is highest during university studies. In spite of their limitations, school-based campaigns are the most effective weapons against smoking. Spanish educational authorities have developed an interdisciplinary anti-smoking curriculum for health education. In practice, however, the curriculum is not usually implemented. An understating of teachers' attitudes toward such campaigns can lead to their better design, contributing to greater cooperation and better outcome. We therefore surveyed teachers participating in the School-based Smoking Prevention Plan during 1993-1995. Teachers had a generally favorable opinion of the campaign and wanted to continue it; they were well disposed to cooperate more actively with the physicians who carried it out.

Adult↗
PubMed1996

Acetylcholinesterase accelerates assembly of amyloid-beta-peptides into Alzheimer's fibrils: possible role of the peripheral site of the enzyme.

Acetylcholinesterase (AChE), an important component of cholinergic synapses, colocalizes with amyloid-beta peptide (A beta) deposits of Alzheimer's brain. We report here that bovine brain AChE, as well as the human and mouse recombinant enzyme, accelerates amyloid formation from wild-type A beta and a mutant A beta peptide, which alone produces few amyloid-like fibrils. The action of AChE was independent of the subunit array of the enzyme, was not affected by edrophonium, an active site inhibitor, but it was affected by propidium, a peripheral anionic binding site ligand. Butyrylcholinesterase, an enzyme that lacks the peripheral site, did not affect amyloid formation. Furthermore, AChE is a potent amyloid-promoting factor when compared with other A beta-associated proteins. Thus, in addition to its role in cholinergic synapses, AChE may function by accelerating A beta formation and could play a role during amyloid deposition in Alzheimer's brain.

Acetylcholinesterase↗
PubMed1996

Structure, function and controls in microbial division.

Several crucial genes required for bacterial division lie close together in a region called the dcw cluster. Within the cluster, gene expression is subject to complex transcriptional regulation, which serves to adjust the cell cycle in response to growth rate. The pivotally important FtsZ protein, which is needed to initiate division, is now known to interact with many other components of the division machinery in Escherichia coli. Some biochemical properties of FtsZ, and of another division protein called FtsA, suggest that they are similar to the eukaryotic proteins tubulin and actin respectively. Cell division needs to be closely co-ordinated with chromosome partitioning. The mechanism of partitioning is poorly understood, though several genes involved in this process, including several muk genes, have been identified. The min genes may participate in both septum positioning and chromosome partitioning. Coupled transcription and translation of membrane-associated proteins might also be important for partitioning. In the event of a failure in the normal partitioning process, Bacillus subtilis, at least, has a mechanism for removing a bisected nucleoid from the division septum.

Bacillus subtilis↗
PubMed1996

Dependency of Escherichia coli cell-division size, and independency of nucleoid segregation on the mode and level of ftsZ expression.

Expression of ftsZ in strain VIP205 is dissociated from its natural promoters, and is under the control of an inducible tac promoter. This abolishes the oscillation in ftsZ transcription observed in the wild type, allowing different levels of ftsZ expression. We demonstrate that this construction does not affect the expression of other genes, and has no effects on replication or nucleoid segregation. A shift in IPTG from 30 microM, that supports division at wild-type sizes, to lower (6 microM) or higher (100 microM) concentrations, indicates that VIP205 cells can divide within a broad range of FtsZ concentrations. Analysis of the morphological parameters during the transition from one IPTG concentration to another suggests that the correct timing of ftsZ expression, and the correct FtsZ concentration, are required for division to occur at normal cell sizes. After a transient division delay during the transition to lower IPTG concentrations, cells in which ftsZ is expressed continuously (yielding 80% of the wild-type FtsZ levels) divide with the same division time as the wild type, but at the expense of becoming 1.5 times larger. A precise control of ftsZ expression is required for normal division, but the existence of additional regulators to maintain the correct timing during the cell cycle cannot be ruled out.

Bacterial Proteins↗
PubMed1996

Immunoglobulin G subclass measurements in recurrent aphthous stomatitis.

We have measured serum levels of IgG subclasses and total IgG, IgA and IgM in a group of 34 recurrent aphthous stomatitis (RAS) patients. At the time of blood collection, 23 of the 34 patients had active oral lesions. The remaining 11 patients were at an inactive stage. All measurement were performed in the Beckmann 360 Array Protein System. Serum levels of IgG2 subclass were significantly lower (P < 0.05) in the whole group of patients (34) when compared to the control group. This relationship was still significant (P < 0.05) when only the 11 patients without active oral lesions were considered but disappeared in patients at an active stage. We conclude that low serum levels of IgG2 may play a role in the pathogenesis of RAS, just as in other recurrent infectious diseases, and that serum levels of this immunoglobulin subclass, as well as total IgA, may undergo transient changes, depending on the different periods of activity and quiescence of the disease.

Adolescent↗
PubMed1995

Acetylcholinesterase, a senile plaque component, affects the fibrillogenesis of amyloid-beta-peptides.

Acetylcholinesterase (AChE) colocalizes with amyloid-beta peptide (A beta) deposits present in the brain of Alzheimer's patients. Recent studies showed that A beta 1-40 can adopt two different conformational states in solution (an amyloidogenic conformer, A beta ac, and a non-amyloidogenic conformer, A beta nac) which have distinct abilities to form amyloid fibrils. We report here that AChE binds A beta nac and accelerates amyloid formation by the same peptide. No such effect was observed with A beta ac, the amyloidogenic conformer, suggesting that AChE acts as a 'pathological chaperone' inducing a conformational transition from A beta nac into A beta ac in vitro.

Acetylcholinesterase↗
PubMed1995

[Smoking of school children in rural Castilla-León environment. Attitudes of the school population].

Tobacco smoking is the most important health problem among school-age children and educational programs aiming at prevention must be taken up by all members of the school community (parents, teachers and students) as well as by health providers. We designed an anti-smoking campaign lasting three years directed towards sixth, seventh and eight-grade elementary school students and secondary school pupils attending classes in the area of Vitigudino (Salamanca). We report the results of student attitude surveys done at the beginning of the program. Sixty-eight percent of boys and 50.7% of girls have smoked at some time. The average age of first contact with tobacco was 12.1 +/- 2.4 years, with boys starting to smoke at a significantly younger age (p < 0.001) than girls. At present, 13.7% of school children smoke. The main reasons given for starting to smoke were that friends smoked (56.9%) and curiosity (55.4%). Tobacco smoking in the family was mentioned by only 29.5% of the students surveyed. Knowledge of medical problems related to smoking was limited. Intention to smoke upon leaving school was reported by 9%, while 46.7% did not know if they would smoke. The fact that only 44.1% of school children believe they will not smoke upon leaving school highlights the need to provide support information that will help students abstain. Programs aimed at school children have been shown to help reduce tobacco smoking in this population. An adolescent who learns to avoid tobacco is unlikely to be a smoker in adulthood.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1994

Correlation between the structure and biochemical activities of FtsA, an essential cell division protein of the actin family.

Cell division protein FtsA, predicted to belong to the actin family, is present in different cell compartments depending on its phosphorylation state. The FtsA fraction isolated from the cytoplasm is phosphorylated and capable of binding ATP, while the membrane-bound form is unphosphorylated and does not bind ATP. A variant of the protein FtsA102, in which the nucleotide binding site was destroyed by mutagenesis of a highly conserved residue predicted to be needed for the binding, does not bind ATP. Another variant, FtsA104, cannot be phosphorylated because the predicted phosphorylatable residue has been replaced by a non-phosphorylatable one. This protein although unable to bind ATP in vitro, is able to rescue the reversible ftsA2, the irreversible ftsA3 and, almost with the same efficiency, the ftsA16 amber alleles. Consequently, phosphorylation and ATP binding may not be essential for the function of FtsA. Alternatively they may have a regulatory role on the action of FtsA in the septator.

Actins↗
PubMed1994

Characterisation of mutant alleles of the cell division protein FtsA, a regulator and structural component of the Escherichia coli septator.

Two alleles of ftsA, a gene that encodes an essential cell division protein in Escherichia coli, have-been mapped at the nucleotide level. The mutations are located inside domains that are conserved in an ATP-binding protein family. The ftsA2 mutation lies in the adenine-binding domain, and the ftsA3 in the ribose-binding domain. The defect in ampicillin binding to PBP3 described for allele ftsA3 is allele-specific. This supports the hypothesis of the existence of different domains in FtsA having different functions.

Alleles↗
PubMed1993

Transcription of ftsZ oscillates during the cell cycle of Escherichia coli.

The FtsZ protein is a key element controlling cell division in Escherichia coli. A powerful transcription titration assay was used to quantify the ftsZ mRNA present in synchronously dividing cells. The ftsZ mRNA levels oscillate during the cell cycle reaching a maximum at about the time DNA replication initiates. This cell cycle dependency is specifically due to the two proximal ftsZ promoters. A strain was constructed in which expression of ftsZ could be modulated by an exogenous inducer. In this strain cell size and cell division frequency were sensitive to the cellular FtsZ contents, demonstrating the rate-limiting role of this protein in cell division. Transcriptional activity of the ftsZ promoters was found to be independent of DnaA, indicating that DNA replication and cell division may be independently controlled at the time when new rounds of DNA replication are initiated. This suggests a parallelism between the prokaryotic cell cycle signals and the START point of eukaryotic cell cycles.

Bacterial Proteins↗
PubMed1993

Detection of antiviral and antitumoral fractions of Chenopodium amaranticolor leaf extract.

Based on the fact that Chenopodium amaranticolor extracts showed inhibitory activity against tobacco mosaic virus (TMV) and Ehrlich tumour (EA), tests were carried out to investigate whether the antiviral and antitumoral activity were caused by the same compounds. When the extract was purified by CM Sephadex C-25 column, after precipitation with 90% ammonium sulphate, twenty active fractions against TMV and two pools of fractions active against EA were obtained. Only one fraction with high absorbance values at 260 and 280 nm was able to inhibit both TMV and EA. When the extract was purified by Bio Gel P-60 column two active fractions against TMV and EA were obtained, suggesting that they were contained in the 0.01 M fraction of the CM Sephadex column. It is suggested that C. amaranticolor leaf extract contained at least two protein-like substances manifesting antiviral and antitumoral activity.

Animals↗
PubMed1993

[Choledocholithiasis following cholecystectomy: what is the real effectiveness of endoscopic sphincterotomy?].

AIM: To assess real efficacy of endoscopic sphincterotomy in the setting of postcholecistectomy choledocolitiasis (i.e., without excluding for analysis any patient referred for the procedures) traditionally the evaluation has been done after excluding those cases in which the procedure failed or was not attempted. DESIGN: Retrospective analysis of a series of cholecystectomized patients with choledocolithiasis. Patients were included for analysis on an "intention to treat" basis, without excluding cases in which the procedure either was not attempted or failed. RESULTS: Out of 122 patients (47.1%) with a firm diagnosis of choledocholithiasis, endoscopic sphincterotomy was performed in 108 (88.5%); in the remaining 13 (10.7%), it was not attempted due to various reasons (among other, five cases of unsuccessful diagnostic cholangiography). In one patient, with a previous surgical sphincteroplasty, calculi were directly extracted. On the whole, stone extraction/expulsion was achieved in 92 cases (including the one patient with previous surgical sphincteroplasty), what represents a success rate of 75.4% on 122 cholecistectomized patients with known choledocolitiasis. Morbidity and mortality reached 9% and 1%, respectively. CONCLUSIONS: If each referred patient is included for analysis of the results of endoscopic sphincterotomy for postcholecistectomy choledocolithiasis (independently of technical success), the therapeutic yield of this procedure lowers significantly compared with the usual estimations.

Adolescent↗