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Biomedical subjects

P Carvalho

Publications and source records attributed to P Carvalho.

50 records · Page 3Linked to original sources
PubMed1991

Accuracy of CT in detecting squamous carcinoma metastases in cervical lymph nodes.

The accuracy of computed tomography (CT) in the assessment of nodal metastases was correlated retrospectively with the pathological examination in 28 patients with known head and neck squamous cell carcinoma, who underwent neck dissections. Three patients had bilateral neck dissections resulting in a total of 31 dissections. CT scanning correctly staged 28 of 31 neck dissections providing an accuracy of 90%, a sensitivity of 87.5% and a specificity of 100% in the detection of nodal metastases. Of the 21 true positives, underestimation of the extent of nodal disease occurred in seven cases. Regarding extracapsular nodal spread, CT resulted in an accuracy of 62%, a sensitivity of 62.5% and a specificity of 60%. All three false negatives for nodal metastases occurred in metastatic spread to the submandibular nodes. The existing criteria for assessment of nodal metastases with CT are sensitive and specific, but in the assessment of extranodal spread CT may not detect 37.5% of cases.

Carcinoma, Squamous Cell↗
PubMed1989

Endoscopic sclerosis of the cardia affects gastroesophageal reflux.

Gastroesophageal reflux disease remains a disorder of unknown etiology associated with abnormal function of the lower esophageal sphincter (LES) and other physiological co-factors of the pathologic reflux. Effective operations for reflux are designed to reinforce the anti-reflux barrier and alter the tendency towards abnormal reflux. We have postulated that the most important component of these procedures is the prevention of distraction of the lowermost components of the LES at the onset of a potential reflux episode. Distraction of the LES causes shortening of the effective sphincter mechanism and can initiate experimental reflux events. In this study we used endoscopic sclerosis of the submucosal space at the cardia as a means of reducing distraction of the cardia in the hope that this would reduce abnormal reflux events. Canine gastroesophageal reflux was induced by intravenous atropine and monitored by continuous esophageal pH monitoring. Sclerosis of the cardia prevented gastroesophageal reflux, without measurable effect on the LES pressure or length. Endoscopic sclerosis of the cardia may be a useful technique in the control of human gastroesophageal reflux.

Animals↗
PubMed1989

The incidence and etiology of the ventilation/perfusion reverse mismatch defect.

Kr-81m ventilation and Tc-99m perfusion images of 392 patients were examined retrospectively for the incidence and etiology of the reverse mismatch defect, which is characterized by a region of lung where the perfusion defect exceeds the ventilation defect. Forty-six patients (11.7%) showed such defects. The most frequent causes were pneumonia (15%), atelactasis (15%), pleural effusions (15%), chronic obstructive airway disease (24%), and bronchial obstruction (31%). The significance of the reverse mismatch defect is discussed.

Adult↗
PubMed1984

Melanotic meningioma complicated by disseminated intravascular coagulation.

The purpose of this paper is fourfold: First, to confirm the rarity of melanotic meningioma, as we have found only 11 reported cases; second to demonstrate that this tumor is not always totally pigmented, a fact that has not been mentioned before; third, to show an unusual recurrence as a hemorrhagic cystic meningioma 10 years and 8 months after removal; and fourth, to describe the association of disseminated intravascular coagulation, a rare disorder with brain tumors.

Disseminated Intravascular Coagulation↗
PubMedDate not supplied

Protein glycation and in vivo distribution of human lens fluorescence.

Glycated proteins formed by the Maillard reaction were measured by furosine determination in human normal lenses and in senile and diabetic cataracts. Furosine, an hydrolysis product of fructose-lysine adduct formed in the early stages of the Maillard reaction, was measured by high performance liquid chromatography (HPLC). Furosine levels in diabetic cataracts were found to be 3 to 4 times higher than those observed for senile cataracts. The increased glycation levels both in cortex and nucleus were related to the increase of fluorescence determined in vitro by fluorometry and in vivo by Scheimpflug photography. Lens proteins were incubated with glucose and it has been demonstrated that protein glycation occurred parallel with the increase in concentration of fluorescent chromophores that present similar characteristics as those observed in vivo. The results indicate that protein insolubilization seemed to involve preferentially glycated proteins and at least in diabetic cataracts, the process seems to be initiated in the cortical region.

Adult↗
PubMedDate not supplied

Endoscopic control of gastro-esophageal reflux: status report.

Gastro-esophageal reflux disease is a common disorder which sometimes requires surgical treatment. Until recently, surgical treatment was the only alternative for severe complications of reflux. During the past 5 years endoscopic treatments for reflux have been reported from several medical centers. These new approaches may herald a new era for the treatment of reflux complications. However, at this time they are purely experimental approaches. Since physiologic antireflux mechanisms involve the muscles of the proximal gastric cardia as well as those of the lower esophageal sphincter, it is not surprising that endoscopic treatments have been directed at these two areas. However, the first endoscopic attempts at reflux control were directed at the lower esophagus sphincter. The most recent efforts at endoscopic control have been aimed at the proximal stomach, based on the concept that scarification beneath the lower end of the esophagus reduces the amount or frequency of reflux. Neither of these latter approaches has been reported in human patients. Since all endoscopic approaches are potentially dangerous, we recommend the adoption of a rigorous protocol for all human application. A possible protocol for this purpose is described herein; the authors will provide data analysis for any cohort of patients receiving endoscopic therapy, and will provide the results of all endoscopic treatments to any serious investigators.

Animals↗
PubMedDate not supplied

Computed tomography of rectal lymphoma.

We present two human immunodeficiency virus positive patients with rectal lymphoma who on CT both demonstrated similar appearances of the rectal tumour, consisting of concentric thickening of the rectal wall and thickening of the levator ani muscles.

Abscess↗
PubMedDate not supplied

BS-SEM evaluation of the tissular interactions between cortical bone and calcium-phosphate covered titanium implants.

The improvement of the reliability of the contact between the osseous tissues and the implant materials has been tested by recovering the metallic implants with ceramic materials, usually calcium phosphates. In our study, the calcium phosphate recovering layers were deposited by means of a pulsed-laser deposition technique. Our aim was to to evaluate the tissue interactions established between cortical bone and titanium implants covered by five different layers, ranging from amorphous calcium phosphate to crystalline hydroxyapatite, obtained by altering the parameters of the laser ablation process. The surgical protocol of the study consisted in the simultaneous implantation of the five types of implants in both the tibial dyaphisis of three Beagle dogs, sacrificed respectively one, two and three months after the last surgical procedures. After the sacrifice, the samples were submitted to a scheduled procedure of embedding in plastic polymers without prior decalcification, in order to perform the ultrastructural studies: scanning microscopy with secondary and backscattered electrons (BS-SEM). Our observations show that both in terms of the calcified tissues appearing as a response to the presence of the different coatings and of time of recovering, the implants coated with crystalline calcium phosphate layers by laser ablation present a better result than the amorphous-calcium-phosphate-coated implants. Moreover, the constant presence of chondroid tissue, related with the mechanical induction by forces applied on the recovering area, strongly suggests that the mechanisms implied in osteointegration are related to endomembranous, rather than endochondral ossification processes.

Alloys↗