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Biomedical subjects

M Rossi

Publications and source records attributed to M Rossi.

At least 415 records · Page 23Linked to original sources
PubMed1993

Surface staining on the villus of lactase protein and lactase activity in adult-type hypolactasia.

BACKGROUND: We have shown in previous studies the presence of a patchy pattern of lactase protein expression in the proximal jejunum of hypolactasic humans, adult rabbits, and rats. The present study investigated the mechanisms underlying the heterogeneous expression of lactase on the villus. METHODS: Proximal jejunal tissue from 18 adult humans and 12 adult rabbits was examined using enzymocytochemical and surface-staining techniques for lactase protein and activity. RESULTS: In the proximal jejunum of hypolactasic humans and adult rabbits, lactase activity is patchily distributed on the villus enterocytes. In humans, the patches of lactase-positive enterocytes are randomly distributed on the villus, whereas in rabbits, vertical, continuous sheets of positive enterocytes arise from the base of the villus. CONCLUSIONS: The presence of enterocytes without lactase activity is one of the mechanisms causing adult-type hypolactasia in the proximal jejunum of humans and mammals. The patchy pattern of lactase in rabbits suggests a clonal origin with heterogeneity of the cells arising from the crypts. In hypolactasic humans, the enterocyte heterogeneity occurs as a consequence of mechanisms that do not have a clonal origin.

Age Factors↗
PubMed1993

Glottic reconstruction by implant of homologous laryngeal cartilages.

This paper describes a case of reconstructive laryngectomy in a patient with epidermoid carcinoma of the glottis. Reconstruction of the skeletal laryngeal architecture was carried out by implanting homologous cartilages, whilst the glottis was reconstructed with sternohyoid muscle. Laryngeal function was restored within 30 days of the operation.

Carcinoma, Squamous Cell↗
PubMed1993

Antiproliferative effects and DNA hypomethylation by 5-aza-2'-deoxycytidine in human neuroblastoma cell lines.

5-Aza-2'-deoxycytidine (5-AZA-CdR) is an inhibitor of DNA methylation, and its antileukemic activity has been shown in preclinical and clinical studies. This paper describes the ability of 5-AZA-CdR to inhibit DNA methylation, DNA synthesis and cell growth in several human neuroblastoma cell lines. The stability of cell growth inhibition was ascertained, as well as the ability of the metabolite thymidine to enhance the antiproliferative effect of 5-AZA-CdR. The activity of phosphorylating enzyme deoxycytidine kinase (dCK) was correlated to different levels of sensitivity in several cell lines. The results obtained indicate that 5-AZA-CdR may be an agent for the chemotherapy of neuroblastoma.

Antigens, Differentiation↗
PubMed1993

Cloning of the gene for cholesterol oxidase in Bacillus spp., Lactobacillus reuteri and its expression in Escherichia coli.

The cloning of the cholesterol oxidase gene in several Gram-positive bacteria, including Lactobacillus reuteri of intestinal origin, was obtained. Only the transformants of Escherichia coli harbouring the recombinant plasmid pCHOA showed a good intracellular enzyme activity. The heterologous gene was stably maintained in Gram-positive transformants but no enzyme activity was detected.

Bacillus↗
PubMed1993

Continuous on-line optical absorbance recording of blood volume changes during hemodialysis.

Conventional techniques that measure blood volume changes during hemodialysis are invasive, hard to reproduce, and provide only intermittent evaluations. To overcome these drawbacks, we have developed an optoelectronic instrument that estimates intradialytic blood volume percentage changes by the optical absorbance of blood. This device is based on the absorption of light transmitted through blood, which is directly related to the hemoglobin concentration. A personal computer interfaced to the device provides a continuous on-line graphic display of the hemoglobin levels and the percentage changes in blood volume. The noninvasive measurement of dialysis blood volume changes by an optical method may be helpful in detecting the appearance of severe hypovolemia that can be dangerous in critically ill patients.

Absorption↗
PubMed1993

The hmc operon of Desulfovibrio vulgaris subsp. vulgaris Hildenborough encodes a potential transmembrane redox protein complex.

The nucleotide sequence of the hmc operon from Desulfovibrio vulgaris subsp. vulgaris Hildenborough indicated the presence of eight open reading frames, encoding proteins Orf1 to Orf6, Rrf1, and Rrf2. Orf1 is the periplasmic, high-molecular-weight cytochrome (Hmc) containing 16 c-type hemes and described before (W. B. R. Pollock, M. Loutfi, M. Bruschi, B. J. Rapp-Giles, J. D. Wall, and G. Voordouw, J. Bacteriol. 173:220-228, 1991). Orf2 is a transmembrane redox protein with four iron-sulfur clusters, as indicated by its similarity to DmsB from Escherichia coli. Orf3, Orf4, and Orf5 are all highly hydrophobic, integral membrane proteins with similarities to subunits of NADH dehydrogenase or cytochrome c reductase. Orf6 is a cytoplasmic redox protein containing two iron-sulfur clusters, as indicated by its similarity to the ferredoxin domain of [Fe] hydrogenase from Desulfovibrio species. Rrf1 belongs to the family of response regulator proteins, while the function of Rrf2 cannot be derived from the gene sequence. The expression of individual genes in E. coli with the T7 system confirmed the open reading frames for Orf2, Orf6, and Rrf1. Deletion of 0.4 kb upstream from orf1 abolished the expression of Hmc in D. desulfuricans G200, indicating this region to contain the hmc operon promoter. The expression of two truncated hmc genes in D. desulfuricans G200 resulted in stable periplasmic c-type cytochromes, confirming the domain structure of Hmc. We propose that Hmc and Orf2 to Orf6 form a transmembrane protein complex that allows electron flow from the periplasmic hydrogenases to the cytoplasmic enzymes that catalyze the reduction of sulfate. The domain structure of Hmc may be required to allow interaction with multiple hydrogenases.

Amino Acid Sequence↗
PubMed1993

Measurement of the bone mineral density of the os calcis as an indication of vertebral fracture in women with lumbar osteoarthritis.

In women with lumbar osteoarthritis, measurement of the os calcis bone mineral density (BMD) using dual-energy X-ray absorptiometry (DEXA) as an indication of vertebral fracture was evaluated. The in vivo precision of the method was 1.28%. Age- and sex-matched control curves were evaluated using a control of 193 females. The correlation between spine BMD and os calcis BMD was significant (r = 0.65, p << 0.001). For the osteoporotic women without osteoarthritis (n = 34), there was no significant difference in the spine and the os calcis Z-scores (-1.99SD and -1.83SD respectively). Whereas for osteoporotic women with osteoarthritis (n = 30) the spine Z-score was -0.49SD the os calcis Z-score was -1.92SD. The difference was significant (p < 0.001). Receiver operating characteristic (ROC) curves demonstrate the superiority of the os calcis as a measurement site over the lumbar spine, in correlation with existing crush fractures in the presence of osteoarthritis. It is concluded that when lumbar osteoarthritis occurs measurement of the os calcis BMD using DEXA is clinically useful for the estimation of bone mass.

Absorptiometry, Photon↗
PubMed1993

[Scintigraphy with radiolabeled granulocytes for the detection of peripheral septic osteoarticular sites].

Radiolabeled granulocyte scintigraphy is a recently introduced technique for detecting osteoarticular infections. Technetium-99m-labeled hexamethylpropylamineoxime (HMPAO), in use since 1986, provides excellent resolution with less radiation exposure than indium-111. Elimination of lymphocytes provides further improvements in image quality and safety, making the technique suitable for use in children. The authors prospectively studied 30 scintigraphies performed with isolated autologous 99mTc-HMPAO-labeled granulocytes to evaluate suspected osteoarticular infection. Image quality was outstanding. In peripheral sites, infection manifested as a focus of increased uptake visible in all three phases (30 min, 3 hours and 18 hours after the injection). Performance was excellent, with 11 true-positive scans, 14 true negative scans, 4 false-positive scans (including two ascribable to recent surgery), and one false-negative scan. Among the 28 evaluable cases, positive predictive value was 85%, negative predictive value was 90%, and sensitivity, specificity, and accuracy were 92%, 88%, and 89%, respectively. The only limitation to routine use of this technique is the need for in vitro granulocyte separation which is time-consuming and requires special precautions to preserve granulocyte function. Nevertheless, these data demonstrate that 99mTc-HMPAO-labeled granulocyte scintigraphy is of value for the detection of osteoarticular infections in patients without chronic inflammatory joint disease.

Acute Disease↗
PubMed1993

[Metallic stents in benign biliary stenosis. A four-year follow-up].

From October 1988 to September 1989, 29 self-expanding biliary metallic stents were positioned in 18 patients with recurrent benign biliary strictures, who were no longer candidates to surgical repair and did not respond to percutaneous balloon dilatation. "Z" stent were used in 17 patients and a Wallstent in one case. At four years' follow-up (range: 39-50, average: 46 months), 10 patients remain asymptomatic, without signs of bile stasis (55.5%), five patients had recurrence of symptoms and were subsequently retreated (27.7%) and three patients died from severe underlying diseases, two of them with stent obstruction, one without signs of bile stasis. Recurrences were caused by stent obstruction in three cases. At four years' follow-up the overall patency rate is 68.7%. According to the type of stricture treated, patency is 100% in the group of patients with single CBD stenosis and in the patients with single anastomotic strictures, whereas in all patients with multiple or complicated strictures the stents completely occluded within 4-22 months.

Adult↗
PubMed1993

[Neuropathy or the brachial plexus associated with pregnancy. Report of a case].

Idiopathic neuropathy of the brachial plexus can appear in two different forms, a sporadic one and a family one, autosomic dominant, much rarer which can be associated with pregnancy. Authors report a clinical case of brachial plexus neuropathy in a patient to the seventh month of pregnancy and with no observation of hereditary disease of nervous peripheric system. Clinical, electrophysiological aspects and possible pathogenetic mechanisms are here debated. Also therapeutic strategies and psychological implications are considered.

Adult↗
PubMed1993

[Calcification of the basal ganglia and Fahr disease. Report of two clinical cases and review of the literature].

Computed Tomography (CT) is superior to conventional skull radiographs in detecting calcifications of the basal ganglia. Basal ganglia calcification has been associated with different conditions, abnormality in the calcium-phosphorus metabolism being the most common of these associations. Some patients, without any evident disease, are well documented and called idiopathics of Fahr's syndrome; less numerous patients present familiar trait, with autosomal dominant inheritance. The correlation of neurological impairment with symmetrical calcification of basal ganglia is not so frequent. Here we present two cases of Fahr's disease, in whom CT aspects were very similar, but the neurological manifestations were different. The review of the literature shows, now, that there is no definite pathogenesis of basal ganglia calcifications.

Basal Ganglia↗