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Biomedical subjects

C Conti

Publications and source records attributed to C Conti.

At least 73 records · Page 4Linked to original sources
PubMed1989

Involvement of carbohydrates in vesicular stomatitis virus-cell early interaction.

The role of N-acetylneuraminic acid and N-acetyl-D-glucosamine containing molecules in vesicular stomatitis virus-cell interaction was studied using specific lectins (limulin and wheat germ agglutinin) and esoglycosidases (neuraminidase, beta-galactosidase, alpha-mannosidase, alpha-fucosidase, beta-N-acetyl-D-glucosaminidase). Lectin treatment of vesicular stomatitis virus (VSV) indicated that carbohydrates of the VSV G envelope glycoprotein were not required for virus infectivity, whereas sialic acid appeared directly involved in the attachment of virus to erythrocytes. The comparative results obtained after enzymatic digestion of cell membrane carbohydrates or their cross linking by lectins demonstrated that whereas VSV infectivity was strongly reduced by pretreatment of chick embryo cells, virus binding to erythrocytes was unaffected by such treatments. We conclude that sugar residues may participate at the host cell attachment site which differs, at least in part, from the membrane binding site of erythrocytes.

Acetylglucosamine↗
PubMed1989

Involvement of lipids in the interaction of Sindbis virus with goose erythrocytes.

The chemical nature of Sindbis virus receptors on goose erythrocytes was investigated by means of two different experimental approaches: by testing the capacity of human serum lipoproteins (HDL, LDL, VLDL) to compete with erythrocytes for virus binding and by enzymatic and chemical modifications of the cell membrane. Each class of lipoproteins was separated into its protein and lipid components which were tested for hemagglutination and hemolysis inhibiting activity. Only the lipid moieties were able to inhibit binding and fusion activities of the virus. Enzymatic treatments of the erythrocyte surface showed that sialic acid and trypsin-sensitive proteins were not involved in Sindbis virus membrane receptor and that some phospholipids probably represent important components of the cellular binding site.

Animals↗
PubMed1988

Malignant progression of papilloma-derived keratinocytes: differential effects of the ras, neu, and p53 oncogenes.

The p117 keratinocyte cell line was derived in culture from chemically induced mouse papillomas. The benignly transformed nature of these cells was demonstrated by their ability to re-form benign papillomas when grafted back onto the animal. Retroviral vectors were used to introduce into the p117 cells three distinct oncogenes: v-Ha-ras, p53, and neu. All three oncogenes were able to induce tumorigenic conversion of the p117 keratinocytes when assayed by subcutaneous injection into nude mice. However, grafting the oncogene-transformed cells onto the back of the mouse revealed important differences in the ability of the three oncogenes to induce a fully malignant phenotype. While the ras-transformed papilloma cells formed aggressive carcinomas, p53 and neu transformation yielded an intermediate phenotype, with formation of large exophytic tumors, not yet invasive but with highly dysplastic features remarkably similar to those of in situ carcinomas. These findings establish a homologous, genetically modifiable cell system in which various stages of malignant transformation can be directly compared.

Animals↗
PubMed1988

Characterization of rat brain cellular membrane components acting as receptors for vesicular stomatitis virus. Brief report.

The chemical nature of the binding sites for vesicular stomatitis virus (VSV) was studied by measuring the ability of solubilized rat brain cell membranes (SRBM) to compete with cultured cells for viral binding. SRBM significantly reduced both binding and infectivity of VSV. After separation of protein and lipid components from membranes, VSV infection was unaffected by the protein fraction, whereas the lipid moiety, specifically phospholipids and glycolipids, showed a dose-dependent inhibitory effect. The essential role of phospholipid and sialic acid-containing glycolipid molecules as receptors for VSV was also suggested by the sensitivity of the inhibitory activity of SRBM and lipid components to phospholipase C and neuraminidase digestion.

Animals↗
PubMed1988

Identification of lipid components of human serum lipoproteins involved in the inhibition of Sindbis virus infectivity, hemagglutination, and hemolysis.

Human serum high density lipoproteins (HDL), low density lipoproteins (LDL) and very low density lipoproteins (VLDL) were isolated and tested for their ability to inhibit Sindbis virus infectivity, hemagglutination and hemolysis. VLDL and LDL produced a strong reduction on both viral infectivity on Vero cell monolayers and attachment and fusion with erythrocytes, whereas HDL appeared to be only a weak inhibitor. Lipid and protein components were extracted from each class of lipoproteins to identify the molecules responsible for the inhibiting activity. Only the lipid moiety was found to inhibit Sindbis virus biological activities. Among the individual lipid components of lipoproteins, neutral lipids (cholesterol, oleic acid and palmitic acid) and negatively charged phospholipids (phosphatidylserine and phosphatidylinositol) and glycolipids (GM 3 ganglioside and cerebroside sulphate) were able to neutralize the virus suggesting that either hydrophobic or electrostatic interactions are involved in the inhibition.

Apoproteins↗
PubMed1988

Inhibition of rabies virus infection by a soluble membrane fraction from the rat central nervous system.

This paper describes the inhibitory effect of a normal rat brain solubilized membrane preparation (RBSM-liposomes) on rabies virus infection. Rabies virus was incubated with RBSM-liposomes or their separated components (proteins, phospholipids, gangliosides) before infection of CER or neuroblastoma cells. In addition, both RBSM-liposomes and target cells were treated with enzymes prior to the infection step. All these experimental procedures showed that the active components were mainly lipids.

Animals↗
PubMed1988

Effects of two different medical treatments on dihydrotestosterone content and androgen receptors in human benign prostatic hyperplasia.

In order to evaluate the biochemical modifications induced by hormonal treatments on human prostatic tissue, the intracellular distribution of tissue DHT and AR were investigated in BPH patients untreated and treated (25-30 days before surgery) with the association of cyproterone acetate (CPA), 100 mg p.o./day plus tamoxifen (TAM), 100 mg p.o./day, or with flutamide (FLU) alone, 750 mg p.o./day. Dextran-coated charcoal and exchange assay in the presence of sodium molybdates (0.2 M) were used for AR determination, employing methyltrienolone as radioligand in the presence of triamcinolone acetonide. Endogenous DHT was measured by RIA, after ether extraction and purification on celite microcolumns. The treatment with CPA plus TAM led to a detection of cytosol AR (ARc) in 50% of the specimens, while nuclear AR (ARn) were never measurable. The FLU treatment did not modify the incidence of ARc, while ARn was not detectable. The cytosolic and nuclear compartmentalization of DHT was scarcely affected by the combined CPA plus TAM treatment, while FLU treatment induced a prevalent cytosolic localization of DHT (DHTc = 283.2 +/- 24.6 S.E. and DHTn = 1138.4 +/- 98.7 S.E. pg/mg DNA in untreated patients; DHTc = 350.4 +/- 97.7 S.E. and DHTn = 589.7 +/- 154.4 S.E. pg/mg DNA in CPA plus TAM treated patients; DHTc = 1101.7 +/- 165.7 S.E. and DHTn = 733.0 +/- 93.9 S.E. pg/mg DNA in FLU treated patients). Both medical treatments, therefore, were able to reduce prostatic growth on account of the reduced value of nuclear DHT content.

Androgen Antagonists↗
PubMed1988

Effect of isoflavans and isoflavenes on rhinovirus 1B and its replication in HeLa cells.

The effect of newly synthesized halogenated isoflavans and isoflavenes on human rhinovirus 1B (HRV 1B) infection of HeLa cells has been examined. Both series of drugs inhibited virus plaque formation in cell cultures, isoflavans being more effective than isoflavenes. Cells pretreated with compounds before challenge with HRV 1B became resistant to the virus-induced cytopathic effect. The antiviral state induced by the most active compounds persisted for at least 10 h and did not appear to be mediated by interferon production. Experiments whereby the compounds were added at varying times indicated that the isoflavans and isoflavenes interfere with early events of virus replication without affecting virus binding to the cell membrane. In addition to their effects on virus multiplication, the isoflavans were also found to have a direct action on the virus. The inhibitory effect on virus infectivity required extraction with chloroform for reversal. Isoflavans also protected the virions against mild acid or heat inactivation.

Cell Survival↗
PubMed1988

Virulence factors of lactose-negative Escherichia coli strains isolated from children with diarrhea in Somalia.

Lactose-negative Escherichia coli strains were isolated at high frequency from children with diarrhea in Somalia during a 2-year study on diarrheal diseases. Sixty-four of these strains, considered to be a representative sample, were characterized for virulence factors, plasmid profiles, and antibiotic resistance. Of these strains, 5 were recognized as enteroinvasive E. coli (they were serotyped as O135:K-:H-), 6 belonged to classical enteropathogenic E. coli serotypes, 9 were able to adhere to tissue culture cells (of these, 4 showed a pattern of localized adherence and 1 was an enteropathogenic strain), 18 were both adherent and hemolytic, and 8 were simply hemolytic. None hybridized with 32P-labeled heat-labile or heat-stable (a and b) enterotoxin gene probes or produced moderate or high-level cytotoxic effects on HeLa cells. Of the 64 strains examined, 24 produced mannose-resistant hemagglutination with human, chicken, and monkey erythrocytes. One of these was serotyped as O4:K-:H8, and a rabbit O antiserum raised against this strain allowed us to establish that 23 strains had the same O antigen. The 23 O4 strains were hemolytic and were not enterotoxic for rabbit ileal loops, and intact bacteria were able to destroy tissue culture cell monolayers very rapidly. The uniformity of the antibiotic resistance pattern and of the plasmid DNA content, together with the fact that they were isolated in different years and in different children, suggests that the O4 strains must be epidemiologically relevant in Somalia. A possible diarrheagenic role for the adherent-hemolytic E. coli strains is also discussed.

Adolescent↗
PubMed1987

Characterization of membrane components of the erythrocyte involved in vesicular stomatitis virus attachment and fusion at acidic pH.

Goose erythrocyte membranes were isolated and tested for their ability to compete with red cell receptors for vesicular stomatitis virus (VSV) attachment and fusion at acidic pH. Crude membranes, solubilized with Triton X-100, Tween 80 and octyl-beta-D-glucopyranoside, showed a dose-dependent inhibitory effect on virus binding and haemolysis. The chemical nature of the active molecules was investigated by enzyme digestion and by separation of purified components. Only the lipid moiety, specifically phospholipid and glycolipid, was found to inhibit VSV attachment; a more detailed analysis of these molecules showed that phosphatidylinositol, phosphatidylserine and GM3 ganglioside were responsible for the inhibitory activity and could therefore represent VSV binding sites on goose erythrocyte membranes. Removal of negatively charged groups from these molecules by enzymic treatment significantly reduced their activity, suggesting that electrostatic interactions play an important role in the binding of VSV to the cell surface. Enzymic digestion of whole erythrocytes confirmed the involvement of membrane lipid molecules in the cell surface receptor for VSV.

Animals↗
PubMed1987

Clinical evaluation of an automatic blood-pressure monitoring device.

Reliability and reproducibility of an automatic ambulatory blood pressure recorder (ICR-5200, Squibb) were tested on 45 subjects (24 normotensives and 21 hypertensives) aged 32-64 (mean age 49). Of 6,566 recordings, 2,376 measurements were cross-checked with a Riva Rocci sphygmomanometer in supine, standing, or sitting position at the beginning and at the end of a 24-hour monitoring period. Moreover, in 11 normotensives and in 11 hypertensives, cross-checking was performed during a cycloergometer effort test. A highly significant linear correlation was found in all the conditions tested (r = 0.98, p less than 0.001 for systolic and r = 0.98, p less than 0.001 for diastolic pressure) either in hypertensives or in normotensives. Only 8% of diastolic measurements performed by the two methods differed more than 5 mmHg. For each subject 5.4 +/- 3.8% of the preprogrammed measurements were lost. Only seven out of 45 subjects referred a disturbed sleep. ICR-5200 seems a suitable and reliable tool for automatic blood-pressure recording.

Adult↗
PubMed1987

[Y chromosome abnormalities and azoospermia. Description of 2 cases].

We describe clinical features and laboratory findings in two azoospermic males with a large Yq deletion involving both the fluorescent and part of the non-fluorescent segment. This report give strong support to the localization of fertility factors in the euchromatic Yq portion.

Adult↗
PubMed1986

Membrane carbohydrate requirement for rabies virus binding to chicken embryo related cells.

The involvement of cellular carbohydrates in the interaction of rabies virus with chicken embryo related cell receptors was investigated. Two different methodological approaches were employed: specific glycosidases were used to treat the cells before infection, and specific lectins were used to compete with the viral binding. The results indicate the participation of sialic acid, galactose, mannose, and N-acetyl-glucosamine but not fucose in the cellular requirements for rabies virus infection.

Animals↗
PubMed1986

[Unexpected positive results in vaginal smears].

Cervicovaginal cytological screening is carried out nowadays at a periodicity dictated by epidemiological experience, in order to detect neoplastic lesions as early as possible. When the vaginal smear test gives an unexpected positive result, a certain number of problems arise which not only relate to the development of lesions but also involve the gynecologist, the laboratory technician and the patient herself. The authors have used three different surveys to study the frequency of this situation and its etiological circumstances, in order to define the conditions that optimize reliability of the cytological examination in daily practice.

Carcinoma in Situ↗
PubMed1986

Effect of concanavalin A on early interactions of Sindbis virus with goose erythrocytes and BHK 21 cells.

The role of mannose containing molecules in Sindbis virus envelope glycoproteins and cell membrane receptors was investigated by means of concanavalin A (con A). Treatment of virus or BHK 21 cells with the lectin before infection reduced viral infectivity. Hemagglutination and hemolysis showed a different sensitivity to con A. Hemagglutination was not affected by the lectin and treatment of erythrocytes with con A produced an enhancement of agglutinability by the virus. Hemolytic activity was, on the contrary, strongly reduced by the lectin. The inhibition observed is due to an action on viral structures and not to an interaction with erythrocyte receptors because con A did not affect the hemolysis when preincubated with erythrocytes.

Animals↗
PubMed1986

Nuclear steroid receptors and dysplasia in adenomatous polyps of the colon as markers of high risk for malignant transformation.

To detect an early colon carcinoma in its stage of carcinoma in situ, colonoscopic examinations with removal of all adenomas of the left colon (particularly of the sigmoid tract and rectum), followed by histological and biochemical evaluations, have been performed on 30 patients. Two-thirds of the adenomas examined presented histological patterns of tubular, tubulovillous, and villous adenomas; those with moderate or severe dysplasia were at high risk of neoplastic transformation. Measurement of estradiol (ER) and progesterone (PR) receptors was performed in the cytosol and in the nuclei of solitary and multiple adenomas and in those with synchronous carcinomas using the dextran-coated-charcoal (DCC) method. Steroid receptors were usually found in the cytosol of the large polyps of male rather than female patients (46% vs 11%) and in the cytosol of the adenomas with moderate or severe dysplasia in male patients. Malignant lesions usually possessed both ER and PR in the cytosol and nuclear fraction. These findings led to hypothesize that patients with adenomas of the colorectal tract with moderate or severe dysplasia and nuclear steroid receptors should be considered at high risk for colon carcinoma and therefore need a special follow-up program.

Cell Nucleus↗