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Biomedical subjects

F Bonvicini

Publications and source records attributed to F Bonvicini.

50 records · Page 3Linked to original sources
PubMed1985

Scanning electron microscopy of normal human corneal epithelium obtained by scraping-off in vivo.

The surface of normal human corneal epithelium was examined by scanning electron microscopy (SEM). The study was carried out on specimens obtained by scraping-off in vivo, and immediately fixed. Four different types of microprojections were observed on the epithelial surface: microridges, microvilli, tufted microvilli and knobs. Detailed high magnification of surface microprojections showed that they consist of subunits. Our data suggest a correlation between surface morphology and maturity of the corneal epithelial cell. An evolutive sequence is proposed, from the youngest cell, provided with microridges, to the oldest exfoliating one, with knobs.

Cornea↗
PubMed1985

Scanning electron microscopy study of human cornea and conjunctiva in normal and various pathological conditions.

Relatively few morphological studies on human cornea have been performed due to the difficulty in obtaining material. The specimens may be obtained either by superficial scraping-off, limited to the epithelial layer, or from corneal buttons obtained at keratoplasty. Conjunctiva, on the other hand, may be obtained by painless biopsy. We have studied the three-dimensional ultrastructure of the normal cornea and conjunctiva and in the course of various diseases where the application of scanning electron microscopy (SEM) seemed to be useful. In the cornea, we studied Fuchs' endo-epithelial dystrophy. In the conjunctiva, we analysed the ultrastructural characteristics of adenovirus follicular conjunctivitis, hay fever conjunctivitis and keratoconjunctivitis sicca. We also considered the problem of contact lens wearing, studying by SEM both the conjunctival tissue and the discarded lenses. On the basis of our results we conclude that SEM supplies useful information which integrates that obtained by biomicroscopy, used by clinicians to interpret the lesions at microscopic level. It is, however, indispensable to carry out, in addition to SEM, an examination on sections to completely investigate the disease.

Conjunctiva↗
PubMed1985

Clinical applications of scanning electron microscopy in gastrointestinal diseases.

We considered the role of scanning electron microscopy (SEM) in clinical investigation of different gastrointestinal diseases. The following clinical applications of SEM may be suggested on the basis of our original data and those reported in literature: in peptic ulcer: assessment of the completeness of healing, by observing the mucosal surface architecture of the scars; identification of mucosal changes, namely enterocytic surface membrane alterations, predictive of recurrence; in coeliac disease: early assessment of the response to gluten-free diet and follow-up of the patients by staging the process of mucosal repair in cerebriform, intermediate and villous patterns; in ulcerative and Crohn's colitis: enhancement of the diagnostic sensitivity of perendoscopic biopsy, by detecting differences in surface structure of mucosa surrounding ulcers in both diseases. This is subverted in ulcerative colitis and preserved in Crohn's colitis. Finally the complementary role of SEM in relation to endoscopy and light microscopy is emphasized.

Adolescent↗
PubMed1984

Ultrastructural aspects of duodenal mucosa repair during treatment of peptic disease.

We applied scanning electron microscopy (SEM) to the study of duodenal ulcer healing during treatment with an H2-receptor antagonist (ranitidine). We also evaluated the changes in the duodenal mucosa close to the lesion, which appeared endoscopically and histologically normal. Endoscopic biopsies were taken from 8 patients both on the edge of the ulcer and in the upper duodenum, before and after 1, 2, 3, 4 and 8 weeks of treatment. Endoscopy revealed a decrease of the ulcer crater after the first week and a complete healing after three weeks of therapy. The ulcer edge presented a subtotal mucosal atrophy, cellular exfoliation (dome-shaped cells) and changes in microvilli (bridging, branching, blebs). In the first week of treatment, reepithelization was observed: however, cellular exfoliation and changes in microvilli persisted at least up to the end of the first month of treatment. Short and stumped villi began to reappear after one month. The mucosa farthest from the lesion showed the same alterations but to a lesser extent. The changes tended to decrease after treatment. Two months after the end of treatment the duodenal mucosa was endoscopically and histologically normal, while SEM showed altered microvilli. SEM allowed us to investigate the morphogenesis of mucosal repair and to identify minimal cellular alterations which could represent the morphological basis of the disease and its possible recurrence.

Adult↗
PubMed1983

Possible role of pirenzepine on the release of pancreatic polypeptide in duodenal ulcer patients: preliminary results of a randomized cross-over study.

The effects of repeated oral doses of pirenzepine (100 mg daily for 7 days) and antacid (Maalox, 105 ml daily for 7 days) on the test-meal-stimulated release of pancreatic polypeptide (PP) were evaluated in 7 duodenal ulcer outpatients by means of a randomized cross-over study, with a wash-out period of one week between pirenzepine and antacid administration. The effects of pirenzepine (100 mg daily for 7 days) were also evaluated in 5 healthy adult volunteers. The stimulus test was performed on each fasting patient two days before the treatment started and after a 7-day treatment. Venous blood samples were obtained before the test meal (basal) and 3, 10 and 30 minutes after it. Plasma PP levels were estimated by means of a specific RIA. The results obtained showed that pirenzepine significantly inhibits the PP response to the test meal in the duodenal ulcer patients and in the healthy volunteers. The above-mentioned effects suggest that one of the mechanisms of action on the therapeutic activity of pirenzepine on peptic ulcer might be explained by the preservation of pancreatic secretion unimpaired by an increase in PP release after meal stimulus.

Adult↗
PubMed1982

Observer variation in assessment of jejunal biopsy specimens. A comparison between subjective criteria and morphometric measurement.

in an observer variation study, the agreement rate reached by a pair of observers who measured 85 jejunal biopsy specimens using surface/volume ratio was compared with that reached by a pair of observers who subjectively assessed the same biopsy series. Both the agreement reached between the subjective observers and that reached between the objective observers proved significant by kappa statistics. However, both total and partial kappa values were greater for the pair of objective observers in every diagnostic category. Moreover, the percentage of agreement on the grading of all biopsy specimens, independent of the diagnostic categories, proved significantly higher for the objective observers. In the pair who made a qualitative assessment, interobserver variation was particularly evident in the grading of partial villous atrophy. Contrastingly, in the pair who made a quantitative assessment, agreement was present in all but one slide. The kappa values for the observers examining the same biopsy specimens on two separate occasions indicated closer agreement rates for the two objective observers. It is concluded that morphometric measurement is more reliable than subjective criteria in the assessment of jejunal biopsy specimens and that qualitative assessment of biopsy specimens should be coupled with quantitative histology.

Atrophy↗
PubMed1979

Lysosomal changes and enterocytic copper deposits in Wilson's disease.

In 4 siblings, of whom 2 had symptoms of Wilson's disease, electron microscopy showed that the number and size of lysosomes in the enterocytes were increased compared with controls. Electron-dense aggregates, observed near the lysosomes in the 2 symptomatic patients and 1 other sibling, were shown, by means of a microanalytical method, to contain copper. These findings could suggest a possible role of the small intestine in Wilson's disease.

Copper↗
PubMed1978

Cholesterol in acute cholestasis induced by taurolithocholic acid. A cytochemical study in transmission and scanning electron microscopy.

Rats were given intravenous injections of a single dose of sodium taurolithocholate, and an almost total cholestasis appeared after 10 minutes and lasted for 3 hours after the injection; then the choleresis began again and 24 hours after the injection, normal values of bile flow were restored. Ultrastructural analysis of the liver during the acute cholestasis and the restoration phase showed, beside usual modifications found in most cases of cholestasis, the "characteristic" alterations of sodium taurolithocholate-induced cholestasis. Cytochemical procedures were used, both in transmission and in scanning electron microscopy, in order to delineate the possible participation of free cholesterol in these cellular modifications. After Williamson's reaction procedure (Williamson JR:J Ultrastruct Res 27:118, 1969), not only were cholesterol-digitonin complexes found in large numbers, both in the hepatocytic cytoplasm and in the biliary canaliculi, but also their morphologic appearance revealed several new features: dark sticks and dark lamellae, frequently adsorbed on the outer surface of crystalline clear material were observed by transmission electron microscopy, and plugs, obliterating parts of biliary canaliculi, were observed using scanning electron microscopy. These observations seem to indicate that a significant amount of free cholesterol is released into the hepatocyte cytoplasm and into canalicular lumina within a few minutes after the infection of sodium taurolithocholate, probably originating from the hepatocytic membranes, especially from those limiting the canalicular lumen. Such a drastic modification in the chemical constitution of these membranes should coincide with a marked modification of their active and passive transport ability.

Animals↗
PubMedDate not supplied

Ultrastructural localization of ConA and WGA receptors on human corneal endothelium.

Corneal endothelial cell plasma membrane plays an important role in maintaining normal thickness and transparency of the cornea. We investigated the molecular organization of endothelial cell membrane using lectins labeled with colloidal gold as ultrastructural probes. We detected the presence of Concanavalin A and Wheat Germ Agglutinin which recognize specific carbohydrate residues of membrane glycoconjugates. We think that this fine cytochemical approach may be useful to better understand the transport mechanisms between aqueous humor and corneal endothelium and to study adaptation and aging of corneal endothelial cells.

Concanavalin A↗