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Biomedical subjects

A Benedetto

Publications and source records attributed to A Benedetto.

At least 55 records · Page 3Linked to original sources
PubMed1993

[The seroprevalence of HIV, HBV and HCV infections in patients coming to the departments of general surgery of a public hospital (S. Camillo, Rome)].

An anonymous unlinked seroprevalence study of HIV, HBV and HCV infections has been conducted on 485 sera consecutively submitted to the virology laboratory to be tested for HBsAg; sera came from patients attending general surgery at San Camillo Hospital in Rome. Carriers of HBsAg were 12 (2.5%); antibodies against HIV have been identified in 4 sera (0.8%) and against HCV in 35 (7.2) by ELISA (first generation assay); 25/35 of anti HCV ELISA positive sera were reactive also by RIBA (first generation assay). The observed prevalences of potentially infectious patients represent a risk of occupational transmission for health care workers. Vaccination against HBV, adherence with universal precautions and development of safer surgical devices and techniques are needed to prevent the risk of exposure and, consequently, of occupational acquired infections.

Adolescent↗
PubMed1993

Heroin addicts infected by HBV and HIV have a low prevalence of HBV DNA in peripheral blood mononuclear cells.

Several reports show that the prevalence of HBV (hepatitis B virus) carriers in HIV (human immunodeficiency virus) infected populations is significantly higher than in HIV seronegative individuals, independent of the risk group for HIV, that is, homosexuals or drug abusers. In this context, evaluation of the simultaneous presence of HBV and HIV in PBMCs (peripheral blood mononuclear cells) is of particular interest for at least 2 reasons: 1) the possible reciprocal influence of the 2 viruses when they infect the same cell; 2) the possibility that HIV-induced hematological disorders could indirectly influence the settling of HBV in blood cell populations. We report data on the frequency of PCR positivity for HBV DNA in PBMCs from 62 HIV infected patients, rigorously selected by risk group, that is, intravenous use of heroin for at least 3 years and syringe promiscuity. Sixty-seven HIV negative individuals who never used any drug formed the control group. The analysis of the cases positive for HBV DNA in PBMCs showed that: 1) the overall prevalence of PCR positivity found in HIV infected patients was significantly lower than that registered in the control group; 2) PCR positivity among the subjects who were HBsAg negative and anti-HBV positive was extremely low in the HIV infected patients (3.7%) but quite frequent in the HIV negative subjects (37.0%). The results support the hypothesis that, unlike the HIV negative individuals, our HIV infected patients exhibited HBV DNA in PBMCS almost exclusively when they presented with active HBV replication.

Adult↗
PubMed1993

Virus-free survival and down-regulation of CD4 in C8166 cells infected with human immunodeficiency virus type 1 at low density.

Compared with other T cell lines, C8166 lymphocytes are particularly susceptible to human immunodeficiency virus (HIV) infection and the outcome is invariably cell death. The results reported in this study demonstrate that the virus-induced cytolysis is strongly dependent on the initial cell density of C8166 cultures. Cultures diluted to 50 to 500 cells/ml almost completely maintained their cell duplication rate and released infectious virus into the medium. HIV infection of diluted C8166 cells is a simple and easily reproducible procedure for obtaining persistently infected cultures. These cultures contained genomic and extragenomic HIV DNA, the latter being assayed by PCR for two-long terminal repeat circular forms. The status of persistent infection disappeared within 2 months. The recovery is due to the replacement of CD4 down-regulated infected cells by overgrowing uninfected cell variants, which are transcriptionally inactive for CD4. The mechanisms underlying the emergence of these variants in persistently infected cultures are considered.

CD4 Antigens↗
PubMed1993

Tumour necrosis factor-alpha increases the sensitivity of human immunodeficiency virus (HIV)-infected monocytic U937 cells to the complement-dependent cytotoxicity of sera from HIV type 1-infected individuals; role of the gp120 protein.

Sera of 40 intravenous drug addicts [25 seropositive and 15 seronegative for human immunodeficiency virus (HIV)] were tested for the presence of cytotoxic antibodies against uninfected and HIV-infected monocytic U937 cells. Six of the 25 seropositive samples proved to be cytotoxic for HIV-infected target cells in the presence of complement. The pretreatment of HIV-infected U937 cells with tumour necrosis factor (TNF)-alpha (which enhances virus production in these cells) increased the detection of serum cytotoxicity and 60% of these sera became cytotoxic. The percentage lysis was also increased after the TNF-alpha treatment of the target cells (from 16.2 +/- 4.5 to 71.2 +/- 4.9). The complement-dependent cytotoxic activity of these sera was significantly reduced by pretreatment with recombinant HIV gp120 antigen. This reduction was dose-dependent in the majority of cases. Immunofluorescence studies suggested that the cytotoxic sera mainly interacted with the viral antigens localized on the membrane of HIV-infected TNF-treated U937 cells. Moreover, comparative Western blot analyses using cellular extracts from untreated and TNF-treated U937 cells showed that there was a positive correlation between the cytotoxic phenotype and the capacity of sera to recognize the gp120 protein in extracts from TNF-treated HIV-infected cells. These results suggest that in some circumstances endogenous TNF-alpha can be a protective factor because it can render persistently infected cells highly sensitive to complement-dependent serum cytotoxicity as a result of increased expression of the relevant viral antigen (gp120) on the cell membrane.

Acquired Immunodeficiency Syndrome↗
PubMed1993

Monocytotoxic antibodies in HIV-infected persons. TNF-alpha treatment of U937 cells increases the complement dependent cytotoxicity.

Sera of 40 intravenous drug addicts were tested for the presence of cytotoxic antibodies against uninfected and HIV-infected monocytic U937 cells. Twelve out of 31 seropositive samples proved to be cytotoxic for HIV-infected, untreated target cells in the presence of complement. The TNF-alpha treatment of HIV-infected U937 cells increased the detectability of cytotoxic effect of sera (21/31). The complement dependent cytotoxic activity of sera was reduced by pretreatment with recombinant HIV gp120. This reduction proved to be dose-dependent in the majority of cases. Immunofluorescence studies indicated that the cytotoxic sera interacted with antigens mostly localized on the cell membrane of HIV-infected TNF-alpha treated U937 cells. The specificity, the possible role and origin of monocytotoxic antibodies in HIV-infected persons is discussed.

Binding, Competitive↗
PubMed1992

Identification of a CD21 receptor-deficient, non-Ig-secreting peripheral B lymphocyte subset in HIV-seropositive drug abusers.

We have studied 61 HIV-seropositive heroin addicts (18 asymptomatic, 20 ARC, and 23 AIDS cases), 26 HIV-seronegative heroin addicts, and 45 healthy blood donors, matching the groups each other for age and sex. We have focused on the phenotypic characteristics of B subpopulations in the peripheral blood of HIV-seropositive and -seronegative drug abusers, paying particular attention to the consistence of the "CD20+" B cell subset, which poorly expresses the CD21 membrane receptor for the C3d and Epstein-Barr virus (EBV) (referred to as "CD20 + CD21-" subset). In healthy blood donors, the ratio CD20 + CD21-/CD20+ x 100 is extremely low (mean +/- SEM = 8.1 +/- 0.9) and rarely exceeds the value of 20. On the contrary, in HIV seropositives, the values are much more dispersed, with higher mean values (mean +/- SEM = 25.8 +/- 1.8) ranging from 50 to 60. An intermediate situation characterizes the class of HIV-seronegative heroin addicts, whose values are slightly higher and more dispersed than that of normal controls (mean +/- SEM = 11.6 +/- 1.3). The extent of the amplification of the CD20 + CD21- subset in HIV-seropositive individuals does not apparently correlate with the progression of the disease and represents an early event in the clinical course of HIV infection. For each subject of the study group, the number of CD20 + CD21- B lymphocytes is not correlated to other early markers of HIV infection, as the T4 lymphocyte number, or total Ig levels in sera. A functional characterization of the CD20 + CD21- B cell subset indicates that, in HIV-seropositive patients, these cells are unable to produce specific and nonspecific immunoglobulins (Ig's), either spontaneously or after pokeweed mitogen stimulation. Furthermore, this cell subset is characterized by poor expression of surface Ig's. The data reported suggest that this cell subset can be regarded as situated at an early level of B cell lineage differentiation.

Adolescent↗
PubMed1992

Prevalence of hepatitis B and C viruses and human immunodeficiency virus infections in women of reproductive age.

OBJECTIVE: To determine the prevalence of hepatitis B and C viruses, and human immunodeficiency virus infections in women of reproductive age attending a health care system. DESIGN: Prospective cross-sectional study. SETTING: Public Obstetric Clinic and Service for Pre- and Perinatal Prevention of Infectious Diseases, Rome, Latium Region, Italy. SUBJECTS: 1142 women attending our centres consecutively for delivery, miscarriage, voluntary interruption of pregnancy or screening for pre- and perinatal prevention of infectious diseases. INTERVENTIONS: Serum samples, collected after informed consent over a period of 2 months, were tested for hepatitis B virus markers (anti-HBc and HBsAg) by enzyme linked immunosorbent assay (ELISA), for antibodies against hepatitis C virus (by ELISA and, if positive, by RIBA) and for human immunodeficiency virus antibodies (by ELISA and, if positive by Western blot). RESULTS: The seroprevalence of hepatitis B virus was 14.4% (95% CI Poisson distribution 12.2-16.5) for anti-HBc and 1.6% (95% CI, 0.9-2.5) for HBsAg. Antibodies against hepatitis C virus were detected by ELISA in 2.4% (CI 1.6-3.5) and by first generation RIBA in 0.9% (CI 0.4-1.6). Human immunodeficiency virus seroprevalence was 1.0% (CI 0.5-1.7). No significant differences were observed by age or by reason for attending. CONCLUSIONS: Women attending our centres have a higher prevalence of hepatitis B virus, hepatitis C virus and human immunodeficiency virus infection than those observed in our country in larger national surveys of newborn babies, in reproductive-aged women or in other selected low-risk groups such as blood donors. This could be due to the attendance of women at increased risk such as drug addicts. The information has the additional value of emphasizing the need for adherence by health care personnel, to the recommendations issued for the prevention of occupational infections.

Adult↗
PubMed1992

Rifamycins as inhibitors of retroviral reverse transcriptase from M-MuLV, RAV-2, and HIV-1.

29 Rifamycins were tested for inhibition of Reverse Transcriptase (RT) as potential anti HIV drugs. Two purified commercial enzymes from M-MuLV and RAV-2 were used. Anti-RT activity was also measured on a crude lysate of HIV-1. The results show that some derivatives have interesting levels of activity on isolated M-MuLV and RAV-2 RTs, while they are less active on the RT in the crude HIV-1 lysate. The active derivatives include oximes and hydrazones, alkylaminoderivatives, open ansa-chain derivatives and derivatives carrying a modified nucleoside.

HIV Reverse Transcriptase↗
PubMed1992

Quinolinehydrazones as inhibitors of retroviral reverse transcriptase.

The inhibitory activity of a series of 2- and 4-quinolinehydrazones on retroviral reverse transcriptase has been studied on enzymes from M-MuLV, RAV-2, and on a crude lysate of HIV-1, assuming the first two enzymes as potential models of the third. The highest activity is mainly found in lipophilic, water soluble 4-quinolinehydrazones. The inhibitory activity of these compounds decreases in changing from the M-MuLV to the RAV-2, and HIV-1 enzymes, in this order.

Cell Survival↗
PubMed1991

Growth properties, differentiation capacity and oncogene expression in metastatic and nonmetastatic Friend leukemia cell variants.

The aims of this study were: (1) to characterize the biologic properties of the WGA-resistant (WR) Friend leukemia cells (FLC) as compared to the original nonmetastatic or highly metastatic FLC; (2) to investigate the possible correlations between the expression of some oncogenes (i.e., c-myc, H-ras and K-ras) and the in vitro and in vivo behavior of FLC. The tumorigenic behavior of the different FLC types strongly depended on the site of tumor injection. Both WR FLC and in vitro passaged FLC did not grow as ascites (when injected intraperitoneally) and developed large solid tumors (when injected subcutaneously), without forming any spleen or liver metastasis. In contrast, in vivo passaged FLC rapidly formed hemorrhagic ascites when injected intraperitoneally; the subcutaneous injection of these cells resulted in the development of solid tumors, which were smaller than the other FLC tumors, but capable of metastasizing to the liver and to the spleen. No significant differences were observed in the in vitro growth characteristics and cell cycle parameters among the different FLC types under various experimental conditions (i.e., FCS concentration or cell seeding densities). Similarly to the metastatic in vivo passaged parental cells, WR FLC exhibited a much lower erythroid differentiation after in vitro addition of either dimethyl sulfoxide or hexamethylene bisacetamide than the in vitro passaged FLC. High levels of c-myc oncogene mRNA were expressed in all FLC variants; no major variations in the c-myc expression were observed in FLC cultivated in medium supplemented with different FCS concentrations and/or seeded at various cell densities. In addition, no changes in the expression of H-ras or K-ras were observed between the different FLC types.

Acetamides↗
PubMed1991

HIV particles detected in spermatozoa of patients with AIDS.

In this paper the Authors describe the presence of HIV particles on and in mature spermatozoa either ejaculated by AIDS patients or incubated in vitro with HIV. Both kinds of spermatozoa have particles localized around the sperm organelles. In the first case, the nucleoid of the virus can be enveloped by a membrane-like coat or be devoid of it and form buddings in the plasma membrane. In the in vitro infected spermatozoa, only membrane enveloped nucleoids are present, and no process of budding can be found. The Authors conclude considering that the spermatozoa of the AIDS patients can be penetrated by the virus particles in different moments of their life, and show the HIV particles in different stages of their cycle: some of them have freshly penetrated the sperm, and are still contained in a membrane-like coat, others are replicated and are budding through the sperm plasma membrane. On the contrary, in vitro infected spermatozoa have only freshly penetrated virus particles, and lack buddings and membrane-free nucleoids. The presence of the HIV virus in spermatozoa is substantiated by labelling with monoclonal or polyclonal anti-HIV antibodies.

Acquired Immunodeficiency Syndrome↗
PubMed1989

Hyposialylation of high-molecular-weight membrane glycoproteins parallels the loss of metastatic potential in wheat-germ agglutinin-resistant Friend leukemia cells.

From the highly metastatic in vivo-passaged Friend leukemia cells (FLC), WGA-resistant (WR) tumor cell variants were selected. These WR FLC had lost their capacity to metastasize when injected i.v. or s.c. into DBA/2 mice. We have characterized the plasma membrane glycoproteins of the different FLC types by: (i) metabolic labelling with (3H)-galactose; (ii) surface labelling with galactose oxidase-borohydride; (iii) direct binding of (125I)-lectins on glycoproteins separated by SDS-PAGE. The ensemble of these approaches showed that the 100- to 200-kDa glycoproteins of in vivo-passaged FLC and WR FLC exhibited a very similar distribution of the terminal galactose in their oligosaccharide moieties. In contrast, the expression of terminal sialic acid was reduced in WR FLC with respect to in vivo-passaged counterparts as appreciated by: (i) binding experiments with (125I)-WGA; (ii) cathodic shift of the 100- to 200-kDa glycoproteins in 2-dimensional electrophoresis studies, and (iii) thiobarbituric acid assay after FLC treatment with neuraminidase. Moreover, binding experiments with (125I)-LPHA, (125I)-ConA and (125I)-WGA (after Smith degradation) indicated that, in the 100- to 200-kDa region, virtually identical asparagine-linked tri- or tetra-antennary complex-type oligosaccharides were expressed in both cell types. We conclude that the sialylation of high-molecular-weight surface glycoproteins (particularly in the 150-kDa region) is strongly associated with the metastatic potential of FLC, especially to the liver.

Animals↗
PubMed1989

Plasminogen activator and its enhancement in differentiating mouse Friend erythroleukemia cells.

Urokinase-type plasminogen activator (u-PA) activity was found in the medium as well as in the lysates of cultured uninduced Friend leukemia (FL) cells. PA activity progressively increased during the cell differentiation induced by dimethyl sulphoxide (DMSO), 4-hydroxy-3-methoxybenzaldehyde or hypoxanthine. Both the differentiation and the enhancement of PA activity in cultures of DMSO-induced cells were blocked by treating the cells with 1 microM dexamethasone. A highly significant correlation (rs = 0.93) was found between the number of hemoglobinized cells and the rate of PA secretion, indicating that the increase in PA activity coincides with late events of the differentiation process. FL cells specifically adhere to fibronectin-coated surfaces but tend to lose this property during the differentiation process. Anti-u-PA IgG antibodies promoted the attachment of differentiating cells to fibronectin-coated surfaces, suggesting that u-PA plays a role in the detachment of FL cells from fibronectin immobilized on the growth substratum.

Animals↗
PubMed1989

Inhibition of virus protein glycosylation as the mechanism of the antiviral action of prostaglandin A in Sendai virus-infected cells.

Prostaglandin A (PGA) inhibits Sendai virus replication at doses non-toxic to uninfected cells. In this report, the antiviral action of PGA was found to be associated with specific alterations of viral protein synthesis. SDS-PAGE analysis of [35S]methionine-labelled proteins showed that while the non-glycosylated viral polypeptides (P, NP and M) were normally synthesized in PGA1-treated cells, the viral glycoproteins HN and F0 were not detected. Two new polypeptides of Mr respectively 4000 and 1000 lower than the HN and F0 proteins were instead detected. The results suggest that these new polypeptides are defectively glycosylated forms of HN and F0. In fact PGA1 was found selectively to inhibit glucosamine incorporation into Sendai virus-infected cells, but not in uninfected cells. Moreover, in infected cells the inhibition of glucosamine incorporation appeared to be selective towards viral polypeptides. This effect was not due to a decreased uptake of glucosamine from the cells after PGA1 treatment. The results also show that the PGA1-induced alteration of the HN protein caused a loss of its biological function and prevented the insertion of this protein into the cell membrane, thereby blocking virus maturation. Finally, a polypeptide of Mr 74K, the synthesis of which was induced by PGA1, appeared to be a possible mediator of PGA1 antiviral action.

Autoradiography↗
PubMed1988

A high proportion of sera of heroin addicts possesses anti-HLA class I and class II reactivity.

The anti-HLA reactivity of sera from 210 heroin addicts was tested by the direct binding with 125I-labeled preparations of HLA class I and class II molecules purified from human B-cell lines of various HLA haplotypes. A high proportion (81.7%) of the sera tested possessed anti-HLA class I and II reactivity. The reactivity did not show any allospecificity and was apparently mediated by antibodies. The control included 100 healthy blood donors, 25 male homosexuals positive for anti-HIV (human immunodeficiency virus) antibodies, and 25 patients positive for HBsAg (hepatitis B surface antigen). Of these controls, only one of the healthy blood donors was positive for anti-HLA reactivity (P much less than 0.001). Among heroin addicts, the reactivity was independent of the presence of either HBsAg or anti-HIV antibodies in the serum.

HLA Antigens↗
PubMed1987

Reduced maturation of Friend virus in adhesive mutants of Friend leukemia cells.

The replication of Friend Leukemia virus (FLV) has been investigated in adhesive clones (FF) of Friend Leukemia cells which were selected via cultivation on top of human fibroblast monolayers. In these adhesive clones a shut-down of FLV production is observed under conditions of culture confluency; this finding is not due either to a reduced number of cell divisions nor to a defective expression of FLV genome as assessed by Northern blot and immunofluorescence studies. Ultrastructural studies showed that virus budding and release into the medium is not detectable under these conditions. Conversely, in confluent FF cell monolayers abundant imperfect type-A enveloped particles were visible, possibly originating from stacks of granular endoplasmic reticulum with thickened membranes. It is postulated that the reduced virus production in adhesive FF monolayers is due to as yet undetermined events taking place during virus maturation at a time coincident with that of cell-cell adhesion under conditions of culture confluency.

Animals↗