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Biomedical subjects

B Rossi

Publications and source records attributed to B Rossi.

At least 163 records · Page 9Linked to original sources
PubMed1992

Characterization and purification of a guanidinobenzoatase: a possible marker of human renal carcinoma.

Guanidinobenzoatases are cell surface-associated proteinases supposed to be involved in cancer metastasis, cell migration, and tissue remodeling. The main features of the guanidinobenzoatase associated with human renal carcinoma plasma membrane are weak membrane association, continuous cleavage of p-nitrophenyl-p'-guanidinobenzoate conversely to the site titration effect of this compound when used with trypsin, and a peculiar sensitivity to serine protease inhibitors, compatible with a poorly active form. Plasma membrane preparation followed by agmatine-trisacryl affinity chromatography allows the purification of guanidinobenzoatase to homogeneity with an apparent enrichment factor of 450. Purified guanidinobenzoatase appears as a single polypeptide chain of M(r) 80,000, likely stabilized by intrachain disulfides bonds. The properties of purified guanidinobenzoatase indicate that it is an original enzyme in spite of some similarities with plasminogen activators. Indeed, in addition to differences in substrate and inhibitor specificity, guanidinobenzoatase is not recognized by specific monoclonal antibodies directed against plasminogen activators or their single-chain precursors. Thus, human renal carcinoma guanidinobenzoatase appears to be an original enzyme whose activity is undetectable in the nontumoral tissue of origin. In this respect, use of purified guanidinobenzoatase would allow us to obtain specific tools to give new insights in cancer cell metastasis.

Adenocarcinoma↗
PubMed1992

Jurkat T cells express a functional neutral endopeptidase activity (CALLA) involved in T cell activation.

We have characterized a T lymphocyte endopeptidase activity that hydrolyses succinyl-alanine-alanine-phenylalanine-paranitroanilide (Suc-Ala-Ala-Phe-pNa). Hydrolysis of this substrate by intact Jurkat T cells was markedly enhanced when exogenous aminopeptidase N was added to the incubation medium. It thus appears that the release of paranitroaniline from Suc-Ala-Ala-Phe-pNA results from the combination of two distinct enzymatic activities: (i) an endopeptidase activity that cleaves the substrate at the alanyl bond and (ii) an aminopeptidase activity that ultimately cleaves the phenylalanyl bond. This cleavage was further confirmed by HPLC analysis. Specific endopeptidase 24.11 inhibitors were shown to inhibit the endopeptidase activity. These features are reminiscent of the characteristics of neutral endopeptidase (NEP, also known as endopeptidase 24.11, CALLA or CD10). Anti-CD10 monoclonal antibodies (mAbs) recognized the CD10+ B cell line Raji, but not Jurkat cells as assessed by FACS analysis. This is probably due to a lack of sensitivity of this method, the level of NEP activity in Jurkat T cells being 3-5% of that measured in B cell lines. Anti-CD10 mAbs immunoprecipitated endopeptidase 24.11 activities in both Jurkat T cells and Raji B cells, demonstrating that T lymphocytes express a CALLA-related endopeptidase. We also demonstrate that T and B cell endopeptidases have the same molecular weight, that T cells express less functional CALLA mRNA than B cells and that there are at least two shorter transcripts (1.8 and 0.8 kb) in both T and B cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗
PubMed1992

Ocular myopathy without ophthalmoplegia can be a form of mitochondrial myopathy.

To characterize muscle pathology in 3 cases affected by ocular myopathy with eyelid ptosis and upper facial weakness, but without ophthalmoplegia, light microscopy and ultrastructural study were performed on levator palpebrae, orbicularis oculi and deltoid muscle biopsies. While levator palpebrae proved uninformative because of the massive fibrous degeneration of muscle, orbicularis oculi biopsies showed histochemical and ultrastructural alterations indicating a mitochondrial involvement, resembling that reported in ocular mitochondrial myopathies (OMM). On the other hand very mild aspecific findings were observed in deltoid. We suggest that these cases with ocular myopathy and without ophthalmoplegia should be considered a partial or initial form of OMM.

Adult↗
PubMed1992

Variability of the expression of muscle mitochondrial damage in ocular mitochondrial myopathy.

In this study we comparatively analysed deltoid histochemistry, biochemistry and mitochondrial DNA (mtDNA) in two groups of ten sporadic ocular mitochondrial myopathies (OMM), respectively with and without ragged red fibres (RRF). (1) All but one RRF--patients presented the mild form of OMM with blepharoptosis but without ophthalmoplegia; (2) the occurrence of cytochrome c oxidase deficient (COX-) fibres was significantly higher in the RRF+ group, but four RRF- cases also showed COX- fibres; (3) no difference was observed in biochemical findings between the groups; (4) two RRF- patients without COX- fibres showed mtDNA heteroplasmy; (5) in two RRF- patients without deltoid mtDNA deletion, biopsy of an eyelid muscle showed significant mitochondrial alterations. These results suggest that the expression of a mitochondrial defect can vary and that the absence of RRF in a skeletal muscle biopsy does not necessarily rule out the diagnosis of OMM, if other data support that.

Adolescent↗
PubMed1992

Clinical and electrophysiological reports in a case of early onset myotonia congenita (Thomsen's disease) successfully treated with mexiletine.

A sporadic event of myotonia congenita in a infant admitted to the Paediatric Clinic for frequent crises of apnoea, cyanosis, vomiting and difficult feeding is reported. EMG analysis was consistent with the dominant variety of myotonia congenita. Mexiletine therapy showed excellent results in reducing myotonic activity. It is worthwhile stressing that early symptoms may go unnoticed or may be misinterpreted and that information on the genetic form of the disease can be obtained also from the EMG analysis through a repetitive stimulation test.

Electromyography↗
PubMed1992

Peripheral neuropathy in mixed cryoglobulinemia: clinical and electrophysiologic investigations.

Peripheral neuropathy has been described in different rheumatic diseases such as rheumatoid arthritis, systemic lupus erythematosus and systemic vasculitis, but usually in limited numbers of patients. Nerve injury is more frequently reported in mixed cryoglobulinemia. In earlier studies generally performed in small series of patients, prevalence of peripheral neuropathy varied widely. We evaluated prevalence of peripheral neuropathy in 33 unselected patients with mixed cryoglobulinemia (25 women, 8 men, aged from 45-71 years). Neurologic involvement was detected using a complete clinical and electrophysiologic assessment, including sensory motor conduction velocities, F wave and H reflex. Neurologic examination revealed a neuropathy in 48% of subjects, while electrophysiologic variables were altered in 82%; a percentage similar to that of subjective symptoms (91%). Among electrophysiologic investigations, F wave was altered in 22/33 subjects (67%); therefore, this variable seems to be the most reliable for the detection of neurologic involvement. Cryocrit levels were significantly higher in patients with peripheral neuropathy: abnormal examination (p less than 0.01), sensory motor conduction (p less than 0.04), and F wave alterations (p less than 0.008). In addition, hemorheological abnormalities seem to contribute to the pathogenesis of nerve injury. Our results indicate that peripheral neuropathy, to a variable degree, is present in the majority of patients with mixed cryoglobulinemia, and a complete clinical and electrophysiologic investigation can be useful for an early and correct diagnosis.

Aged↗
PubMed1991

Neoadjuvant chemotherapy, surgery, and postoperative radiation therapy for invasive thymoma.

Between January 1988 and June 1990, seven previously untreated patients with histologically confirmed and clinically staged IIIa invasive thymoma (IT) were enrolled in a prospective, single treatment arm study of neoadjuvant chemotherapy (NC) followed by surgery and postoperative radiation therapy (4600 to 6000 cGy). The NC included three cycles of cisplatin (75 mg/m2 on day 1), epirubicin (100 mg/m2 on day 1), and etoposide (120 mg/m2 on days 1, 3, and 5), every 3 weeks. All patients showed a partial response (greater than 50%) and underwent complete (n = 4) or incomplete (gross [n = 1] or microscopic [n = 2] residual tumor) surgical resection. Histologic examination was negative for two completely resected patients. Projected 2-year survival was 80%; all patients but one currently are alive and disease-free. This approach appeared to be feasible and may be a new therapeutic choice in the management of IT, but its use on a regular basis should be reserved until a larger number of patients and longer follow-up are available.

Adult↗
PubMed1990

Effects of selenium and vitamin E on muscular strength and blood parameters in Steinert disease.

Six patients with Steinert disease were treated with selenium and vitamin E, for a 24 month period, including a first phase of 12 months, 6 months wash-out interval and a second treatment phase of 6 months. Mean segmental strength values showed significant improvement during the first 12 months of therapy, while marked reductions of serum enzymes CPK, SGOT, SGPT and gamma-GT were observed in some patients. The results support the hypothesis that selenium may play a role in the development of muscle damage in Steinert disease.

Adult↗
PubMed1990

Clinical and electrophysiological findings in two cases of Miller Fisher syndrome.

Clinical, radiological and electrophysiological data in two patients with 'Miller Fisher syndrome' (MFS), characterized by ataxia, ophthalmoplegia and areflexia are reported. Of the many tests performed only the electrophysiological findings provided any clue to the site of the lesions and the structure involved, showing a significant pattern of brainstem dysfunction. The authors discuss the role of central and peripheral lesion theory in the light of these data and stress that electrophysiological findings lend considerable weight to the former and support the hypothesis that MFS should be recognize as a distinct clinical entity.

Ataxia↗
PubMed1990

Myokymic syndrome with impaired muscular relaxation: further evidence of a possible paraneoplastic genesis.

A case of concomitant myokymia with impaired muscular relaxation and hypertrophic osteoarthropathy associated with the presence of two separate lung malignancies is described. Both the neurological syndrome and osteoarticular disorder significantly improved after surgical removal of the lung cancers. The possibility that common mechanisms may underlie these two tumour-related disorders is also discussed.

Adenocarcinoma↗
PubMed1990

Cell-cycle regulation of insulin-stimulated tyrosine aminotransferase activity in rat hepatoma cells.

Amongst the proteins that are subjected to variation during the cell division cycle few are under hormonal regulation. The variation in amount of tyrosine aminotransferase (TAT) in the hepatic tissue is under the control of glucagon, glucocorticoids and insulin. It has been reported that the inducibility of TAT activity by dexamethasone in rat hepatoma (HTC) is limited to the late G1 and the S portions of the cell cycle. Evidence is presented in this report that in the rat hepatoma Fao, insulin (which has the capability to promote both cell growth and hormonal effects via its own receptors) modulates the TAT activity during the cell cycle. The maximal insulin-stimulated induction of TAT activity was observed at the end of the G1 phase and then decreased as cells progressed through their mitotic cycle. The number of insulin binding sites per cell was decreased by only 30% during the same period of time. Furthermore, the extent of receptor autophosphorylation decreased in the same proportion, suggesting that insulin receptors remained functional through the whole cell cycle. In fact, another insulin-stimulated cellular function, neutral amino-acid transport, was not modified as cells progressed into the S phase. Hydroxyurea, which is known to prevent cell progression into the S phase, stabilized the insulin-induced TAT activity at its maximal level for several hours. Reciprocally, removal of hydroxyurea resulted in a concomitant decrease in TAT activity and reinitiation of DNA synthesis.

Amino Acids↗
PubMed1990

Wheat-germ agglutinin mimics metabolic effects of insulin without increasing receptor autophosphorylation.

Expression of insulin metabolic effects can be obtained by anti-receptor antibodies without activation of the tyrosine kinase activity [O'Brien R. M., Soos M. A. and Siddle K. (1987) EMBO J. 6, 4003-4010; Forsayeth J. R., Caro J. F., Sinha M. K., Maddux B. A. and Goldfine I. D. (1987) Proc. natn. Acad. Sci. U.S.A. 84, 34,448-34,514; Ponzio G., Contreres J. O., Debant A., Baron V., Gautier N., Dolais-Kitabgi J. and Rossi B. (1988) EMBO J. 7, 4111-4117; Hawley D. M., Maddux B. A., Patel R. G., Wong K. Y., Mamula P. W., Firestone G. L., Brunetti A., Verspohl E. and Goldfine I. D. (1989) J. biol. Chem. 264, 2438-2444; Soos M. A., O'Brien R. M., Brindle N. P. J., Stigter J. M., Okamoto A. K., Whittaker J. and Siddle K. (1989) Proc. natn. Acad. Sci. U.S.A. 86, 5217-5221.]. Recently, we have proposed that receptor cross-linking is sufficient in itself to stimulate glycogen synthesis, even if aggregation was performed on receptors mutated on Tyr 1162 and Tyr 1163 and thus devoid of tyrosine kinase activity [Debant A., Ponzio G., Clauser E., Contreres J. O. and Rossi B. (1989) Biochemistry 28, 14-17]. The aim of this study was to gain information on the involvement of receptor clustering in the expression of the different insulin biological effects. To this end, we studied the mimetic effects of wheat-germ agglutinin, which is likely to induce receptor aggregation without interacting with the receptor protein moiety. Wheat-germ agglutinin failed to promote DNA synthesis, whereas the lectin behaved as a potent mimicker of insulin on tyrosine aminotransferase activity and amino-acid transport. However, this stimulatory effect did not parallel the activation of receptor autophosphorylation. Our data reinforce the idea that the expression of the metabolic effects of insulin are not strictly dependent on a general tyrosine kinase activation.

Aminoisobutyric Acids↗
PubMed1990

Inhibitors of chymotrypsin-like activities selectively block the mitotic pathway in rat hepatoma cells.

We provide evidence that both covalent and non-covalent inhibitors of chymotrypsin-like activities inhibit the insulin-induced DNA replication, while the hormonal metabolic effects such as induction of tyrosine aminotransferase activity or increase of amino-acid transport remain unchanged. Besides, the protease inhibitors that we tested were without any effect on both the autocatalytic phosphorylation of insulin receptors and the tyrosine kinase activity towards poly(glutamate/tyrosine). The inhibitory effect of protease inhibitors on DNA synthesis was also visible when fibroblast growth factor (FGF) was used to commit cells in the proliferative cycle. This observation proves that the involvement of a putative protease is not restricted to the insulin mitogenic pathway. Finally, we observed that Fao cells totally escaped the inhibitory action of a covalent inhibitor of chymotrypsin after having been exposed to insulin for 10 h. We propose that a chymotrypsin-like activity is involved in the intracellular signalling leading to the proliferation of rat hepatoma cells up to a non-return point situated in the middle of G1 (6-8 h).

Aminoisobutyric Acids↗
PubMed1989

Type 1 fiber abnormalities in skeletal muscle of patients with hypertrophic and dilated cardiomyopathy: evidence of subclinical myogenic myopathy.

Abnormalities of skeletal muscle have been described in patients with dilated and hypertrophic cardiomyopathy. Eleven patients with dilated and eight with hypertrophic cardiomyopathy without overt symptomatic skeletal myopathy underwent extensive neuromuscular studies. Quantitative electromyography showed abnormal reduction of motor unit potential duration, indicative of myogenic myopathy, in four patients (36%) with dilated and in three (37%) with hypertrophic cardiomyopathy. Values were 21% to 40% (mean 28%) lower than those in age-matched normal control subjects. The presence of normal nerve conduction velocities and of normal motor unit fiber density in all patients indicated lack of neurogenic abnormalities. Skeletal muscle biopsy was performed in five patients with dilated and in four with hypertrophic cardiomyopathy. In all nine patients light and electron microscopy showed central hyporeactive cores, selective atrophy and mitochondrial abnormalities of type 1 fibers but not of type 2 fibers. The degree of impairment of left ventricular function in patients with electromyographic abnormalities was similar to that of those without (percent fractional shortening at two-dimensional echocardiography 21 +/- 9 versus 25 +/- 10, ejection fraction at angiography 39 +/- 13% versus 42 +/- 13% and left ventricular end-diastolic pressure 21 +/- 6 versus 21 +/- 8 mm Hg) as well as symptom duration (9 +/- 4 versus 12 +/- 8 months). Thus, subclinical electromyographic alterations indicative of myogenic myopathy are frequent in patients with dilated and hypertrophic cardiomyopathy and are unrelated to the degree of impairment of left ventricular function. The concomitant histologic alterations, characterized by selective type 1 atrophy, are similar to those observed in congenital and idiopathic myopathies, but different from those described in secondary heart failure.

Adult↗
PubMed1989

Characterization of a natural inhibitor of the insulin receptor tyrosine kinase: cDNA cloning, purification, and anti-mitogenic activity.

Amino acid sequence of the precursor of the phosphorylated N-glycoprotein (pp63) secreted by rat hepatocytes was deduced from the cDNA sequence. This polypeptide (Mr = 40,586) was rich in both cysteine and proline and contained three potential N-glycosylation sites. A single pp63 mRNA species (approximately 2000 bp), found in normal hepatocytes but not in FaO hepatoma cells, appeared to result from transcription of a single gene. pp63 purified by affinity chromatography inhibited insulin receptor tyrosine kinase and receptor autophosphorylation. Only the phosphorylated form of the protein was active. In additon, pp63 antagonized the growth-promoting action of insulin in FaO cells but did not affect hormone-mediated increase in amino acid transport capacity or tyrosine aminotransferase induction in these cells.

Acute-Phase Proteins↗