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Biomedical subjects

A Silva

Publications and source records attributed to A Silva.

At least 55 records · Page 3Linked to original sources
PubMed2000

The role of alpha-CaMKII autophosphorylation in neocortical experience-dependent plasticity.

Calcium/calmodulin kinase type II (CaMKII) is a major postsynaptic density protein. CaMKII is postulated to act as a 'molecular switch', which, when triggered by a transient rise in calcium influx, becomes active for prolonged periods because of its ability to autophosphorylate. We studied experience-dependent plasticity in the barrel cortex of mice carrying a point mutation of the alpha-CaMKII gene (T286A), which abolishes this enzyme's ability to autophosphorylate. Plasticity was prevented in adult and adolescent mice homozygous for the mutation, but was normal in heterozygotes and wild-type littermates. These results provide evidence that the molecular switch hypothesis is valid for neocortical experience-dependent plasticity.

Age Factors↗
PubMed2000

Management of tracheal agenesis.

Complete tracheal agenesis is a very rare congenital anomaly that is only compatible with life in some cases with associated tracheo-oesophageal or broncho-oesophageal fistula. In most cases, concomitant congenital anomalies of the heart, digestive tract or genitourinary tract are present. It should be suspected in any neonate with a history of hydramnios, absent crying, respiratory distress and difficulty in intubation. The possibility for surgical correction or palliation rests on the extent of atresia present. We present a case of complete tracheal agenesis without tracheo nor broncho-oesophageal fistula (type II by Floyd's classification) - the diagnosis of which was prenatally suspected - and discuss the important features of the airway management of this condition.

Abnormalities, Multiple↗
PubMed2000

Telereconstruction from computerized tomography images for the distance teaching of medicine.

A system for making remote two- and three-dimensional reconstructions from computerized tomography images has been developed in order to improve medical teleteaching. It allows the automatic two- and three-dimensional remote visualization of the anatomical structure of interest. As a part of this system, software has been developed which allows many visual operations or transformations on a remote three-dimensional model. It permits the remote workstation and the local workstation to visualize every transformation simultaneously. It allows a doctor to interact virtually and remotely with the anatomical structure. The software enables examination of the anatomical model from all angles, even from inside (including planar and three-dimensional presentations).

Education, Distance↗
PubMed2000

Image processing from computerized tomography images: virtual reconstruction for telediagnosis.

We have developed a system for remote three-dimensional reconstruction, which facilitates telediagnosis. The telereconstruction system is based on a computerized tomography (CT) scanner, a workstation connected to the CT scanner, a PC, which can be geographically far away from the workstation, and a computer program that we have developed. The workstation allows CT images to be stored and image processing to be carried out. The PC permits the user to control the workstation in making a three-dimensional reconstruction and allows the remote user to see that reconstruction. From the PC various graphical operations can be performed on the three-dimensional model, such as rotations, translations and cuts through the model. The program therefore allows a remote user to have three-dimensional images and to study them by means of all the options the program provides.

Image Processing, Computer-Assisted↗
PubMed2000

Levels of interleukin-1 beta, -8, and -10 and RANTES in gingival crevicular fluid and cell populations in adult periodontitis patients and the effect of periodontal treatment.

BACKGROUND: Various cytokines have been identified at sites of chronic inflammation such as periodontitis. Cytokines are synthesized in response to bacteria and their products, inducing and maintaining an inflammatory response in the periodontium. The purpose of the present study was to investigate the involvement of interleukin-1 beta (IL-1 beta), IL-8, and IL-10 and RANTES (regulated on activation, normally T cell expressed and secreted) and the cell populations associated with the immune response in destructive periodontitis, as well as the effect of periodontal therapy on cytokine levels in gingival crevicular fluid (GCF). METHODS: Data were obtained from 12 patients with moderate to advanced periodontitis and 6 healthy controls. Patients presenting at least 2 sites with > or =2 mm clinical attachment loss were included in the destructive periodontitis group. After monitoring for 4 months, only 6 patients showed destructive periodontitis and GCF samples and soft tissues biopsies were collected from these patients. GCF samples and biopsies were collected both from active (12 CGF samples and 6 biopsies) and inactive (12 CGF samples and 6 biopsies) sites. The comparison with healthy controls was carried out by collecting GCF samples from 6 healthy volunteers (12 samples) and biopsies during the surgical removal of wisdom teeth. In periodontal patients, clinical data and GCF samples were obtained prior to periodontal treatment (72 samples) and 2 months after periodontal therapy (72 samples). GCF was collected using a paper strip; eluted and enzyme-linked immunoabsorbent assays (ELISA) were performed to determine cytokine levels. The inflammatory infiltrate was analyzed by immunohistochemistry of gingival biopsy samples with monoclonal antibodies against CD3, CD8, CD4, CD11c, and CD19 antigens. RESULTS: Cellular components of the inflammatory infiltrate include B and T lymphocytes and monocyte/macrophages. Active sites contained a higher number of B lymphocytes and macrophages. IL-8 and IL-1 beta and RANTES in GCF were detected in the majority of sites from periodontal patients (100%, 94% and 87%, respectively); IL-10 was found in only 43%. IL-8 was the only cytokine detected in the GCF (75%) of the control group. Moreover, IL-1 beta levels were significantly higher in active sites versus inactive sites (P <0.05). IL-8 and IL-10 and RANTES were increased in active sites; however, differences were not significant (P>0.05). A positive correlation between the IL-8 and RANTES (r = 0.677, P<0.05) was observed in periodontitis patients. Periodontal therapy reduced the total amount of IL-1 beta, IL-8, and IL-10 and RANTES. Data showed a weak correlation between the clinical parameters and the total amount of cytokines in periodontitis. CONCLUSIONS: These data suggest that the amount of crevicular IL-1 beta, IL-8, and IL-10 and RANTES is associated with periodontal status. Removal of the bacterial plaque reduces the antigenic stimuli and consequently could modulate the chemokines present in GCF. We propose that the dynamic interactions between cytokines, their production rates, and their quantity could represent factors controlling the induction, perpetuation, and collapse of the cytokine network present in the periodontal disease.

Adult↗
PubMed2000

Inertially compensated force plate: a means for quantifying subject's ground reaction forces in non-inertial conditions.

A system for the measurement of forces in noninertial reference systems, and a possible solution to compensate force plate readings by means of accelerometers were investigated. If the force plate can be considered a rigid body, six linear accelerometers can measure all linear and angular accelerations of the instrument in 3-D space. However, by using nine accelerometers in a proper layout, the force and moment generated by the movement of the plate can be quantified in a way that eliminates the errors due to the time integration of the accelerations. By doing so, no temporal limits are imposed to the compensation. A one degree of freedom numerical model was implemented to evaluate the importance of main error sources in the estimation of inertial forces using accelerometers with different technical characteristics. The inertial compensation of the force plate along one axis was tested, and the performances of a piezoelectric accelerometer and a capacitive accelerometer were compared. With the proposed inertially compensated force plate, accelerations up to 5 g's in amplitude and frequencies from 0 to 100 Hz can be compensated by means of capacitive accelerometers. Such a device can be used for force measurements in moving vehicles, or any situation where the surface on which the instrument is mounted is moving or vibrating.

Acceleration↗
PubMed1999

Endoscopy during laparoscopy. Reduced postprocedural bowel distention with intraluminal CO2 insufflation.

BACKGROUND: Intraluminal endoscopy during laparoscopy can substitute for manual palpation in defining anatomy and pathology, but a potential problem is the persistent bowel distention associated with intraluminal air insufflation. METHODS: To compare the rates of intraluminal absorption, a 30-cm segment of small bowel with an intact vascular supply was insufflated with either air or CO2 during CO2 pneumoperitoneum. Intraluminal pressures and bowel circumferences were monitored after the insufflation was stopped. To study the metabolic and hemodynamic effects of CO2 endoscopy during laparoscopy, the small bowel was insufflated to an intraluminal pressure of 15 mmHg during CO2 pneumoperitoneum. Nitrogen pneumoperitoneum was used to differentiate the effects from intraluminal and peritoneal CO2 insufflation. RESULTS: The intraluminal pressures remained elevated and the bowel distended for the entire 3 h following bowel insufflation with air. Following intraluminal CO2 insufflation, both the intraluminal pressures and the bowel circumferences returned to preinsufflation values within 15 min. Intraluminal CO2 insufflation also led to systemic absorption of CO2 with significant metabolic and hemodynamic changes. These changes were effectively corrected by doubling minute ventilation. CONCLUSIONS: Intraluminal CO2 was absorbed faster than intraluminal air. Although decreased bowel distention is certainly of practical value, endotracheal intubation needs to be done to effectively ventilate the absorbed CO2.

Air↗
PubMed1999

Fibronectin interaction with alpha4beta1 integrin prevents apoptosis in B cell chronic lymphocytic leukemia: correlation with Bcl-2 and Bax.

B cell chronic lymphocytic leukemia (B-CLL) consists of the accumulation of malignant cells that apparently escape normal apoptotic regulation. We have studied the role of alpha4beta1 integrin/fibronectin interaction in preventing apoptosis of these cells in vitro. B cells from 16 patients showed constant expression of alpha4beta1 and little or no alpha5beta1. B-CLL cells cultured on fibronectin or two previously described fibronectin recombinant fragments (H89 and H0) which contain the ligands for alpha4beta1, consistently showed higher viability than control cells cultured on poly-lysine. The H89 fragment, containing the high affinity ligand CS-1, was the most efficient substrate with mean cell viability values of 72, 60 and 35% at days 2, 5 and 8 of culture, respectively. For control cells these values were 40, 27 and 15%, respectively. Parallel cell cycle analysis confirmed these results. The anti-apoptotic effect required direct contact with immobilized substrata since it was not observed when using B-CLL conditioned media alone or when clustering alpha4beta1 with specific mAbs in suspension. Quantitation of the apoptosis regulatory proteins Bcl-2 and Bax revealed that cells cultured on the H89 fragment showed high/moderate levels of Bcl-2 (with some interpatient variation) and low levels of Bax resulting in an elevated Bcl-2/Bax ratio. These results indicate that adhesion of B-CLL cells to fibronectin upregulate the Bcl-2/Bax ratio and this may contribute to the anti-apoptotic effect induced via alpha4beta1 integrin.

Adult↗
PubMed1999

Blue rubber bleb naevus: case report and literature review.

Blue rubber bleb naevus syndrome is a rare cutaneous-digestive angiomatosis, described first by William Bean in 1958. Today, there are more than 200 cases published. The dangers of this syndrome include angiomata in the brain, kidneys or lungs (due to vasculature obliteration by in situ thrombosis). Patients are scanned with technetium-labelled red blood cells in order to identify the affected organs. Multiple techniques are used to treat the lesions by gastrointestinal endoscopy.

Aged↗
PubMed1999

Preliminary assessment of the safety and immunogenicity of a new CTXPhi-negative, hemagglutinin/protease-defective El Tor strain as a cholera vaccine candidate.

Vibrio cholerae 638 (El Tor, Ogawa), a new CTXPhi-negative hemagglutinin/protease-defective strain that is a cholera vaccine candidate, was examined for safety and immunogenicity in healthy adult volunteers. In a double-blind placebo-controlled study, no significant adverse reactions were observed in volunteers ingesting strain 638. Four volunteers of 42 who ingested strain 638 and 1 of 14 who received placebo experienced loose stools. The strain strongly colonized the human small bowel, as evidenced by its isolation from the stools of 37 of 42 volunteers. V. cholerae 638, at doses ranging from 4 x 10(7) to 2 x 10(9) vibrios, elicited significant serum vibriocidal antibody and anti-Ogawa immunoglobulin A antibody secreting cell responses.

Adult↗
PubMed1999

Helicobacter pylori infection in indigenous families of Central America: serostatus and oral and fingernail carriage.

Helicobacter pylori infection remains one of the most common in humans, but the route of transmission of the bacterium is still uncertain. This study was designed to elucidate possible sources of infection in an isolated, rural population in Guatemala. A total of 242 subjects in family units participated in the study. A medical history, including a history of dyspepsia, was taken by a physician and immunoglobulin G antibodies to H. pylori were detected with the QuickVue (Quidel, San Diego, Calif.) onsite serology test. Overall, 58% of subjects were seropositive, with a positive relationship between mother and child (P = 0.02) and a positive correlation between the serostatuses of siblings (intraclass correlation coefficient = 0.63). There was no association between serostatus and gastric symptoms. Oral H. pylori was detected from periodontal pockets of various depths and the dorsum of the tongue by nested PCR. Eighty-seven percent of subjects had at least one oral site positive for H. pylori, with the majority of subjects having multiple positive sites. There was no association between periodontal pocket depth and the detection of H. pylori. Nested PCR was also used to detect H. pylori from beneath the nail of the index finger of each subject's dominant hand. Overall, 58% of subjects had a positive fingernail result, with a significant positive relationship between fingernail and tongue positivity (P = 0.002). In conclusion, the results of this study suggest that oral carriage of H. pylori may play a role in the transmission of infection and that the hand may be instrumental in transmission.

Adolescent↗
PubMed1999

[Elective coronary angioplasty in acute coronary syndromes: early versus delayed treatment].

BACKGROUND: In patients with acute coronary syndromes (ACS) the optimal time required to stabilize the patient before attempting coronary intervention (PTCA) is uncertain. The recent use of newer devices and antiplatelet drugs allowed earlier percutaneous intervention. OBJECTIVE: We examined the efficacy and safety of coronary angioplasty in patients with ACS according to the period of stabilization with medical therapy. METHODS: We included 83 patients, 15 female, 54 with unstable angina and 29 with non-ST elevation myocardial infarction. We studied the rate of complications related to the procedure, the duration of CCU and hospital stay according to the period of stabilization with medical therapy: < 48 hours (early PTCA) and > or = 48 hours (delayed PTCA). RESULTS: No significant differences were found between the two groups of patients with respect to success rate (92% in early PTCA vs 98% in delayed PTCA), stents implantation (74% vs 78%), use of abeiximab (42% vs 24%), abrupt closure during procedure (3% vs 2%), infarct related procedure (0% vs 7%), re-PTCA (5% vs 7%) and surgical revascularization (0% vs 2%). No deaths occurred, CCU stay (2.5 vs 6.7 days, p < 0.001) and hospital stay (4 vs 9.4 days, p = 0.001) were significantly shorter in the group of early PTCA. CONCLUSIONS: In the present group of patients with ACS, early coronary intervention was a safe procedure with a shorter CCU and hospital stay compared with deferred PTCA.

Abciximab↗
PubMed1999

Bilateral groin adenolymphoceles: an unusual presentation of chylous reflux.

We report an unusual presentation of a young man with bilateral groin lymph nodal adenolymphoceles and right leg lymphedema as a manifestation of intestinal lymphangiectasia. Chylous reflux was supported by conventional and isotopic lymphography as well as by a total lipid test showing delayed triglyceride absorption 24 hours after ingestion of 60 gm of butter. After excision of groin masses in conjunction with dietary control (short-medium chain triglycerides), manual massage, pneumatic compression, and long-term wearing of a low stretch elastic garments he remains well.

Adult↗
PubMed1998

Beta2-adrenergic agonist residues: simultaneous methyl- and butylboronic derivatization for confirmatory analysis by gas chromatography-mass spectrometry.

A derivatization procedure for confirmatory residue analysis of beta2-agonists is described. Methyl (MBA) and butyl (BBA) boronic acids are simultaneously used for the derivatization of tulobuterol, mabuterol, mapenterol, salbutamol, clenproperol, clenbuterol, clenpenterol and bromobuterol by GC-MS determination. A temperature of 55 degrees C during 60 min was selected as optimal temperature-time condition for simultaneous MBA and BBA beta2-agonists derivatization. It was also observed that stability of boronic derivatives was maintained at -20 degrees C over a period of four days. The proposed methodology was tested in urine and it could be applied for confirmatory residue analysis of clenbuterol-like compounds.

Adrenergic beta-Agonists↗
PubMed1998

Effect of contralateral masking on the latency of otoacoustic emissions elicited by acoustic distortion products.

Otoacoustic emissions (OAE) are sound products generated by the outer hair cells (OHC) in the inner ear. The OHC are capable of moving spontaneously or in response to acoustic stimuli (spontaneous otoacoustic emissions and evoked otoacoustic emissions), these movements are known as electromotility. Electromotility is affected when contralateral acoustic stimulation is introduced to the ear. Different types of stimuli may produce this response. Clicks, pure tones, and white masking noise have been used as contralateral stimulation. This effect appears to be mediated by the medial efferent olivocochlear bundle. Contralateral masking produces suppression of OAE, especially on the amplitude. However, the effect of contralateral masking on the latency of distortion product otoacoustic emissions (DPOAE) has not been studied. The purpose of this paper is to investigate whether contralateral masking, with wide band masking noise, may produce a significant change on the latency of the DPOAE. Three different latency measurements of DPOAE measurements were made on low, middle and high frequencies of fl including 574 Hz, 2454 Hz and 4919 Hz. Each one of these frequencies was measured with and without contralateral masking. Twenty-eight ears of 15 subjects were studied. Non-significant differences (P > 0.05) between masked and unmasked conditions were found in all cases. It is concluded that contralateral masking does not appear to affect latency of DPOAE.

Audiometry↗
PubMed1998

Replicating function of the RS1 element associated with Vibrio cholerae CTX phi prophage.

The RS1 element associated with Vibrio cholerae CTX phi prophage was cloned from an E1 Tor biotype Vibrio cholerae strain. We used the recA- vaccine strain Peru-15, that lacks the target for RS-mediated site-specific integration, to show that RS1 promotes autonomous replication of a suicide vector. A linker insertion in the rstR open reading frame abolished autonomous replication in Peru-15 but not in a strain containing an RS1 in the chromosome. An AT-rich region containing cis-acting elements involved in autonomous replication was identified by deletion. This region was sufficient to support autonomous replication in a strain containing an RS1 in the chromosome. DNA sequence analysis of a region present in RS1 and not RS2 revealed the presence of putative binding sites for host proteins involved in plasmid replication. These results indicate that RS1 contains a replicon distinct from RS2 which could be involved in replicative recombination events associated with tandem amplification of the CTX element.

Bacteriophages↗