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Biomedical subjects

R Guimaraes

Publications and source records attributed to R Guimaraes.

12 recordsLinked to original sources
PubMed1994

MR lymphography with superparamagnetic iron nanoparticles in rats: pathologic basis for contrast enhancement.

OBJECTIVE: The purpose of this study in rodents was to determine the pathologic basis for enhancement patterns of hyperplastic and tumours lymph nodes shown by MR lymphography after IV injection of superparamagnetic iron oxide nanoparticles (AMI-227). MATERIALS AND METHODS: Hyperplastic and tumorous lymph nodes were imaged in vivo at 1.5 T 1 day after IV administration of AMI-227 (40-200 mumol Fe/kg) to rats. Inguinal and axillary lymph nodes were surgically resected, and in vitro imaging was done by using the same magnet with a prototype coil that allowed a pixel size of 70 x 230 microns. Imaging findings were correlated with histologic findings and iron staining of the nodes. RESULTS: With all sequences, at doses of 80 mumol Fe/kg or higher, the signal intensity of hyperplastic nodes was lower than on unenhanced images. The same pattern was seen in the remaining normal tissue of tumourous lymph nodes. This T2* effect was a result of clustered particles inside macrophages in the lymphatic sinuses. At doses of 200 mumol/kg, the tumor itself consistently showed an increase in signal intensity on T1-weighted images. This T1 effect probably resulted from particles leaking into the interstitial spaces of the tumor. CONCLUSION: After IV injection of superparamagnetic nanoparticles, a decrease in signal intensity indicates active uptake of particles into macrophages, whereas an increase in signal intensity indicates altered capillary permeability in tumor. These findings in rats may prove to be clinically useful in the future for differentiating benign from malignant enlarged lymph nodes.

Animals↗
PubMed1993

Intraabdominal serous fluid collections after appendectomy: a normal sonographic finding.

OBJECTIVE: The significance of sonographic findings 1 week or less after appendectomy is difficult to evaluate without knowing the inconsequential abnormalities that may occur in these patients. Accordingly, we performed postoperative sonography on patients who had a normal course after appendectomy to determine the findings that can be considered normal within 1 week after surgery. SUBJECTS AND METHODS: Forty-four patients who had an appendectomy for acute appendicitis and who had normal findings at clinical follow-up 5 days and 6 months later were included in the study. In all patients, sonograms were obtained on the fifth postoperative day and interpreted by a radiologist who did not know the surgical findings. RESULTS: Ten fluid collections (23%) were found in the pericecal area, ranging in size from 10 x 10 mm to 40 x 20 mm. The collections were hypoechoic or anechoic, crescent-shaped, and immobile. Fluid collections were more common in cases of suppurative appendixes (6/20, 30%) than in cases of inflamed appendixes (4/19, 21%) and in retrocecal appendixes (3/9, 33%) than in normally located appendixes (7/34, 21%). However, the differences were not statistically significant (p > .05). CONCLUSION: Inconsequential fluid collections are detected with considerable frequency on postoperative sonograms 5 days after an appendectomy. Consequently, not every fluid collection should be considered an abscess.

Abdomen↗
PubMed1984

An in vivo study of corneal surface morphologic features in patients with keratoconjunctivitis sicca.

We used wide-field color specular microscopy to study the corneal epithelium of 13 normal subjects and 13 patients with keratoconjunctivitis sicca. The frequencies of small, medium, and large cells were different in the two groups, with a shift to small cells in patients with keratoconjunctivitis sicca. Increased uptake of rose bengal dye, filaments, coarse mucus plaques, and pre-exfoliative sheets were also found in the patients with keratoconjunctivitis sicca. These findings suggest accelerated epithelial cell loss from the surface of the eye in keratoconjunctivitis sicca.

Cornea↗
PubMed1984

The effect of concentrated antibiotics on the rabbit's corneal epithelium.

The effect of concentrated antibiotics on the healing rate of epithelial erosions in rabbit was measured by serial standardized photography. Histological studies were also performed. Our results suggest that Kanamycin 30 mg/ml (p less than 0.001), Penicillin 100,000 units/ml (p less than 0.001) and Vancomycin 31 mg/ml (p less than 0.01) administered six times a day retard the epithelial wound healing compared with control animals which received isotonic NaCl.

Administration, Topical↗
PubMed1984

Color specular microscopy of disorders involving the corneal epithelium.

Color specular microscopy, a noninvasive, in vivo microscopic technique, was utilized to study the corneal epithelium in 17 patients including eight with keratoconus, seven with bullous keratopathy, and two with Fuchs' corneal dystrophy. Color specular microscopy was also performed on rabbit corneas with experimental surgical trauma. Changes observed by specular microscopy in these diseased states correlated with alterations noted by light microscopy and scanning and transmission electron microscopy. Specular microscopy can provide detailed in vivo cellular morphology of the ocular surface, obviating the need for tissue biopsy. Thus, specular microscopy is a valuable diagnostic technique available for the clinician to monitor changes of the diseased ocular surface.

Animals↗
PubMed1984

[Urrets-Zavalia syndrome and glaucomatous cataract. Etiopathogenic and nosologic discussion].

After penetrating keratoplasties for different congenital or acquired corneal diseases, the presence of characteristic cataracta glaucomatosa lens opacities was noted in 9 cases of fixed, dilated pupil iris atrophy of Urrets-Zavalia. This association--rarely mentioned in the literature--is an opportunity to study again the different physiopathological theories on this syndrome (pupillary block by mydriasis with hypertony, upsetting of iris neurovegetative balance, particular sensitivity of ocular tissues to the surgical aggression in keratoconus), to analyze their arguments, and the preventive measures that proceed from them. The almost complete extinction of this type of complication of the corneal graft surgery, since the routine use of these preventive measures, proves the multifactorial origin of this syndrome.

Adolescent↗
PubMed1984

Comparison of the effects of EGF, pFGF and EDGF on corneal epithelium wound healing.

EDGF, a growth factor purified from bovine retina is able to increase the rate of wound healing of rabbit corneal epithelium in a dose dependent way. Two applications a day are enough to obtain the maximum rate. The most purified preparation of EDGF is as effective as EGF or pFGF in promoting this phenomenon and allows the epithelium to reach its normal organization earlier. Excess addition of EDGF did not adversely affect the normal or healed epithelium.

Administration, Topical↗
PubMed1983

Antibiotics and corneal epithelial wound healing.

The healing of a de-epithelialized cornea was measured by serial standardized photography after treatment with different antibiotics. Histological studies were also performed. Low doses of bacitracin (500 units/mL), gentamicin sulfate (3 mg/mL), neomycin (3.5 mg/mL), and chloramphenicol (4 mg/mL) did not retard normal epithelial healing. However, higher doses of bacitracin (10,000 units/mL), gentamicin sulfate (10 mg/mL), and neomycin (8 mg/mL) significantly inhibited reepithelialization.

Animals↗
PubMed1982

Effect of acetylcysteine (Mucomyst) on epithelial wound healing.

The rate of reepithelialization of the rabbit cornea, receiving isotonic NaCl solution and acetylcysteine (Mucomyst) solution at 10 and 20% concentrations, following a superficial epithelial ulcer was studied by fluorescein staining, photography and light microscopy. Acetylcysteine solution does not seem to retard normal epithelial healing compared with control animals which received isotonic NaCl solution.

Acetylcysteine↗