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Biomedical subjects

F Ameglio

Publications and source records attributed to F Ameglio.

At least 91 records · Page 5Linked to original sources
PubMed1992

Recombinant glycoprotein 120 of human immunodeficiency virus is a potent interferon inducer.

Cells infected with human immunodeficiency virus (HIV) induce antiviral activity in peripheral blood mononuclear cells (PBMC) from healthy donors. This activity is neutralized by anti-interferon-alpha antibody and partially destroyed at pH 2. Previous studies with enriched cell populations and monoclonal antibodies suggest that B lymphocytes are the main IFN-producing cells, and that both CD4 and HLA class II antigens are essential for IFN induction. Since the initial event of HIV infection of CD4+ cells is the interaction of the virus coat glycoprotein gp120 with CD4 molecule, we investigated whether gp120 is responsible for IFN induction. Using PBMC and recombinant gp120 obtained from a baculovirus expression system, dose-dependent induction of antiviral activity was observed with titers approaching 10(3) IU/ml. This induction was blocked in the presence of antibody to gp120. The antiviral activity was characterized as IFN-alpha by neutralization with IFN alpha-specific antibody. Preincubation of PBMC with anti-CD4 or the presence of soluble CD4 during incubation inhibited IFN induction, indicating that interaction of gp120 with cell-associated CD4 is responsible for this induction. Neither lymphoproliferation nor interleukin-2 (IL-2) production was observed during IFN induction. However, class G immunoglobulin secretion was enhanced by gp120, indicating that B cells are direct or indirect targets of gp120 stimulation in this experimental system. Since gp120 is shed from HIV-infected cells and occurs in the serum of acquired immunodeficiency syndrome (AIDS) patients, our data suggest that this glycoprotein is responsible for the induction of endogenous IFN and the polyclonal activation of B cells both of which are observed in AIDS patients.

B-Lymphocytes↗
PubMed1992

Acid lability is not an intrinsic property of interferon-alpha induced by HIV-infected cells.

Human immunodeficiency virus (HIV)-infected cells induce acid-labile interferon-alpha (al-IFN-alpha) in cultures of mononuclear cells from peripheral human blood. We have investigated the physiochemical properties of such preparations to elucidate the reasons for acid-lability of this IFN. Al-IFN-alpha is a mixture of both glycosylated and unglycosylated molecules as shown by separation on Concanavalin-A Sepharose. Acid-lability is associated only with glycosylated molecules. Upon chromatography of the glycosylated fraction on Sepharose coupled to IFN-alpha-specific antibody, the portion of the IFN that is retained and eluted with guanidine-HCl is acid-stable, whereas the excluded antiviral activity is acid-labile, and is partially neutralized by antibodies to either IFN-alpha or IFN-gamma. Also, upon further purification of the unglycosylated fraction on the same antibody column, all antiviral activity remains indistinguishable from conventional IFN-alpha. Reconstitution experiments showed that glycosylated material excluded from the anti-IFN-alpha column potentiates antiviral activity of the IFN that is specifically retained by the column. This potentiation is abolished by acid treatment. Similar results are obtained with al-IFN-alpha from the serum of acquired immunodeficiency syndrome (AIDS) patients, indicating that its acid-lability is also the consequence of an acid-labile component that is capable of enhancing the antiviral activity. The potentiation of antiviral activity obtained by combining recombinant preparations of IFN-alpha and IFN-gamma suggests that the cooperating molecule is IFN-gamma.(ABSTRACT TRUNCATED AT 250 WORDS)

Acids↗
PubMed1992

The association of Helicobacter pylori infection with low levels of urea and pH in the gastric juices.

Fifty-four gastric biopsies and their relative gastric juices were analyzed for the presence of Helicobacter pylori with both cultural and microscopic methods. Thirty-one samples were positive and twenty-three were negative. These data were therefore employed as references for the subsequent comparisons. Furthermore, the gastric juices were later tested to establish the urea concentration and the pH level. In addition, the sediment obtained after centrifugation was microscopically observed for the possible presence of other bacterial flora in the sample (unstained smears). The urease test on the bioptic specimens has also been evaluated. The presence of H pylori was strictly related to urea levels of less than 15 mg/dl and pH less than 3.5. Furthermore, H pylori was generally not associated with the presence of other bacterial flora (only 1 out of 12 samples). The latter instead, was almost exclusively present in high pH samples (with the exception of one). On the basis of these results, a simple diagnostic scheme was constructed to identify carrier subjects. All patients (14/14) with urea levels of more than 15 mg/dl were found to be negative as well as those presenting a pH of more than 3.5 (7/9) or evidence of other bacteria in the juices (8/9). The remaining subjects (30/31 or 29/31, respectively) presented H pylori in the gastric juices. The final classification was 96.3% (or 94.4%) correct.

Female↗
PubMed1991

Thymopentin and interleukin-2 in combination with 5-fluorouracil and leucovorin in metastatic colorectal adenocarcinoma: preliminary results.

Thymic hormones have been shown to exhibit immunorestorative effects in vivo and in vitro, and to enhance the expression of high affinity interleukin-2 (IL-2) receptors on normal human lymphocytes stimulated with phytohemagglutinin. Based on these data, a clinical trial was initiated to determine the effects of the combination of 5-fluorouracil (5-FU) and folinic acid (FA) with thymopentin (TP-5) and interleukin-2 (IL-2) in patients with advanced colorectal carcinoma. Fifteen patients were treated with FA, 200 mg/m2/day by IV bolus, and 5-FU, 400 mg/m2/day as a 30-minute infusion, both given for 5 consecutive days every 28 days. TP-5, 50 mg/day, was administered subcutaneously on days 8-11, and IL-2, 9 million IU/m2 twice daily, was given subcutaneously on days 12-16. Of 8 patients evaluable for response, 4 achieved a response. Two patients had stable disease, and two progressed during treatment. There were no instances of life-threatening toxicity. Two patients developed grade III stomatitis and diarrhea followed by leukopenia and fever, requiring hospitalization. Other toxicities were moderate. These results are only preliminary, and a larger number of patients and longer follow-up are needed to draw meaningful conclusions about the merits of this new approach in cancer treatment.

Adenocarcinoma↗
PubMed1991

Detection of Helicobacter pylori carriers by discriminant analysis of urea and pH levels in gastric juices.

An alternative approach to the problems inherent in current methods for detecting Helicobacter pylori carriers--that of being generally time-consuming, expensive, and not sufficiently sensitive--was devised by using the urea concentration and pH levels of gastric juices. A linear discriminant analysis of these variables, measured in 54 patients submitted to digestive endoscopy for gastritis, provided a mathematical formula for assigning the subjects (previously classified by other standard methods) to groups of either positive or negative H pylori carriers. The results obtained showed a correct classification in 52 out of 54 cases with only one false negative and one false positive case.

Adult↗
PubMed1990

Thrombocytopenia during immunotherapy with interleukin-2 by constant infusion.

PURPOSE: To elucidate some of the possible mechanisms that lead to interleukin-2 (IL2)-induced thrombocytopenia. PATIENTS AND METHODS: We evaluated retrospectively the effects of immunotherapy with IL2 in 76 patients with disseminated cancer. The lymphokine was administered by constant infusion, daily for 6 days a week for 4 consecutive weeks. RESULTS: A significant decrease in platelet counts was seen after the first 6 days of therapy in all but two patients: 14 patients experienced grade 2 or 3 toxicity, 21 had grade 1 toxicity, and although the decrease in platelet counts could not be graded as toxicity in the remaining 41 patients, there was an average decrease of 32% from baseline platelet counts in 39 (p less than 0.0001). Thrombocytopenia appeared to be secondary to peripheral platelet destruction, since bone marrow biopsy specimens obtained during thrombocytopenia showed hyperplastic megakaryocytopoiesis. IL2 is inactivated by tubular resorption, and severity of thrombocytopenia was strongly correlated with IL2-induced renal dysfunction (p = 0.0004). Additionally, both renal dysfunction and thrombocytopenia were related to total dose of IL2 and were more pronounced in patients with worse baseline renal function and lower baseline platelet counts. The incidence of thrombocytopenia increased with subsequent IL2 therapy: life-threatening thrombocytopenia (less than 25,000/microL) was seen in nine of 57 patients, five of whom required transfusional platelet support. CONCLUSION: On the basis of preliminary observations, we hypothesize that thrombocytopenia induced by IL2 is caused by accelerated clearance of platelets by the reticuloendothelial system.

Adolescent↗
PubMed1990

Dose and schedule effects of cisplatin on the related acute iron changes.

To investigate the relationships between cisplatin and the related erythropoiesis impairment, 14 patients receiving very-high-dose cisplatin (40 mg/m2/day for 5 days) and 17 patients receiving standard-high-dose cisplatin (either a single dose of 100 or 20 mg/m2/day for 5 days) entered this study. Iron, ferritin, hemoglobin, and reticulocyte levels were evaluated before, 4 and 6 days after each course of cisplatin. A complete blood count was obtained weekly. During the 1st week after chemotherapy, iron and ferritin levels significantly increased, and the reticulocyte count decreased. Iron changes depend on the cisplatin dose, but are not related to the different schedules employed. The severity of subacute anemia was found to be dependent on the cisplatin dose administered and on hemoglobin pretreatment levels. Some relationships between cisplatin, iron changes, and the subacute hemoglobin decrease are described.

Adult↗
PubMed1990

"Giant cell" production by C. albicans cultured in xylitol.

"Giant cell" production by C. albicans cultured in the presence of substances belonging to the pentitol family is described in this study. After two days of incubation, at pentitol concentrations ranging between 0.1 and 20 mg%, the production of very large, frequently multibudding cells became evident. Their number increased with time, in some cases reaching 20% of the culture cells and their size could exceed 25 mcm. Comparisons with other sugar/alcohols and with other Candida spp. are presented. A possible explanation of this observation is consistent with an accumulation of pentitol catabolites in the yeast cytoplasm followed by an increased osmotic strength and cell swelling.

Candida albicans↗
PubMed1988

Very high-dose cisplatin-induced ototoxicity: a preliminary report on early and long-term effects.

Acute and subacute audiometric hearing changes were evaluated in 12 patients receiving 35 courses of very high-dose (vhd) cisplatin (200 mg/m2 per course) in hypertonic saline at 4 or 8-week intervals. Audiogical evaluations were performed both before and immediately after each course of chemotherapy, and again after the discontinuation of treatment. A significant drop of the mean hearing threshold (P less than 0.01) at high frequencies was observed even within 48 h from the end of the first course of therapy, with 50% of the patients presenting a hearing loss of more than 15 dB. At the same total dose (200 mg/m2), one course of this regimen provided an incidence of hearing loss of more than 15 dB, which was four times greater than that reported with two courses of standard-dose regimens. The incidence and severity of the hearing impairment progressed further with subsequent courses of chemotherapy. Compared with baseline levels, most patients (75%) receiving at least two courses had a moderate to severe hearing loss, especially involving 4 and 8 kHz. At the end of treatment, 33% of the patients complained of a nondisabling functional hearing impairment. No recovery occurred after chemotherapy had been discontinued for 9-28 weeks. At this dose level cisplatin is markedly ototoxic. The use of hypertonic saline and vigorous hydration are effective means of minimizing the risk of nephrotoxicity, but seem to have no effect on cisplatin-related ototoxicity.

Adult↗
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↗
PubMed1988

Chemoprophylaxis of bacterial infections in granulocytopenic cancer patients using norfloxacin.

Sixty-five cancer patients pretreated with chemo or radiotherapy, with granulocytopenia less than 1000/mm3 and without fever, were entered into this study: 30 of them were submitted to prophylaxis with norfloxacin while the remaining 35 patients were used as a control group. 20% of the treated subjects versus 68.6% of the controls presented a subsequent infection (P less than 0.001), the lung representing the most frequent site of the infectious disease in both groups (3/6 and 14/24 respectively). These data strongly suggest the use of norfloxacin as an effective prophylactic drug in nonfebrile, granulocytopenic cancer patients, especially as far as gram-negative infections are concerned. Because of the high prevalence of lung cancer in the patients of our study, and a related prevalence of lung infections, at the present time, a wider use of this antibiotic in every kind of solid tumor cannot be generalized.

Agranulocytosis↗
PubMed1987

Changes in serum iron levels following very high-dose cisplatin.

A four-fold (P less than 0.001) mean increase in iron levels was found in 18 patients (a total of 36 courses of therapy) with ovarian cancer at the end of a 5-day course of cisplatin (40 mg/m2 per day every 4-5 weeks). The kinetics of these modifications began very early (24-48 h after initiation of therapy): they reached their maximum on the 4th-5th day, coinciding with the last drug administration, and basal levels were recovered after the 10th day. A subsequent eight-fold average increase (P less than 0.001) in ferritin serum levels, beginning 2 days after the iron changes, was observed, but showed a slower regression (after the 15th day). Reticulocyte counts were lowered (P less than 0.001) with the same time-course of the iron increases, but returned to pretreatment levels within 2 weeks. Total bilirubin and serum glutamate-pyruvate transaminase showed significantly delayed increases compared with iron. The results are in keeping with a reduced iron utilization by the erythroid precursors, but other mechanisms cannot be excluded. There is no statistical correlation between the early iron increases and the subsequent hemoglobin nadir values.

Cisplatin↗