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Biomedical subjects

L Silvestro

Publications and source records attributed to L Silvestro.

At least 145 records · Page 8Linked to original sources
PubMedDate not supplied

In vitro chemosensitivity testing of leukemic cells: development of a semiautomated colorimetric assay.

A rapid chemosensitivity assay was developed, employing the human continuous leukemic cell lines HL 60, K 562, FLG 29.1. This automated colorimetric assay is based on the characteristic of viable, metabolically active cells to cleave p-iodonitrotetrazolium violet (INT) into a red formazan derivative, whose optical density is readable at 492 nm by an automated microtiter-plate reader photometer. A linear relationship was found between the viable cell number and the optical density of INT cleaved by the cellular samples. Dead cells did not reduce INT and did not interfere with the formazan derivative generation and the photometric reading. Leukemic cell lines were also tested for INT formazan derivative generation after exposure to antileukemic drugs at various concentrations, representative of plasma levels obtainable in vivo. A dose-dependent inhibition was detected, with different sensitivity patterns, related both to the drugs and to the different cell lines. A significant correlation between the viable cell number and the amount of tetrazolium salt cleaved was also demonstrated after drug exposure. INT assay allows the processing of a great number of samples and gives the opportunity to screen several drugs, saving time and yielding fully reliable results.

Autoanalysis↗
PubMedDate not supplied

In vitro chemosensitivity testing of leukemic cells: prediction of response to chemotherapy in patients with acute non-lymphocytic leukemia.

The in vitro chemosensitivity to daunorubicin and cytosine arabinoside of blast cells derived from 35 patients affected by acute non-lymphocytic leukemia was assessed by a semiautomated tetrazolium-based colorimetric assay, by the use of p-iodonitrotetrazolium violet. The results of the in vitro testing were then compared a posteriori to clinical outcome of patients, who followed a schedule of therapy which always included the drugs tested in vitro. Three dosages of drugs were employed to allow the determination of a dose-response curve, which was obtained for all the patients. The data collected in INT assay correlated with the clinical sensitivity of patients, evaluated in terms of achievement of complete remission. For the dosage of ARA-C 500 ng/ml it was possible to establish a significant cutoff between responders and non-responders to therapy, while an acceptable distribution of sensitivity/resistance prediction was found for DNR 500 ng/ml and 5 micrograms/ml. Present results, together with rapid and easy execution of the test, encourage the use of INT assay in screening leukemic patients' sensitivity to antiblastic drugs before treatment or, in case of resistance to classical chemotherapy, in detecting individual sensitivity to alternative drugs.

Adolescent↗
PubMedDate not supplied

Adhesion inhibition "in vitro" by heparin derivatives correlates with their activity on angiogenesis in mice.

Heparin (HEP) play an important role in angiogenesis. Inhibition of matrix degrading enzymes and binding to adhesion molecules are some of the interaction mechanism. The bleeding risk and the need of parenteral administration, restrict the therapeutic use of HEP as angiogenesis modulator; presently derivatives, with different pharmacokinetic and anticoagulant properties, are available. In this study the "in vitro" anti-adhesion activity, tested with PMNs and endothelial cells, was compared with the effect on angiogenesis, evaluated in Matrigel implanted mice. Some HEP derivatives, with low anticoagulant activity, showed a significant angiogenesis inhibition. A positive correlation between adhesion inhibition in vitro and anti-angiogenesis effect in vivo was found suggesting that the interaction with adhesion molecules by HEP derivatives play a relevant role in the angiogenesis control.

Animals↗
PubMedDate not supplied

Sentinel lymph node and breast cancer staging: final results of the Turin Multicenter Study.

AIM OF THE STUDY: Validation of the sentinel node (SN) technique in breast cancer by means of lymphoscintigraphy. MATERIALS AND METHODS: From December 1996 to January 1999 102 T1-T2 breast carcinoma cases were recruited in Turin. 99mTc-human serum albumin colloids were injected subdermally the day before surgery (mean activity, 5.2 +/- 2.5 MBq). Scintigraphic imaging was performed after injection. After identification of the SN during surgery by a hand-held gamma probe, the SN was excised and sent for histologic examination. SN histology was compared with that of other axillary nodes. RESULTS: The SN detection rate was 86.3%; among 88 cases with an identified SN, 37 (42%) had axillary metastases; the SN was metastatic in 35 cases (sensitivity, 94.6%); in 51.3% of pN+ cases (19/37) the SN was the only metastatic site. In two of the 53 negative SNs, SN histology did not match with that of the remaining axilla (negative predictive value, 96.2%; staging accuracy, 97.7%). CONCLUSIONS: Our results agree with those reported in the literature; however, except in clinical trials and experienced structures axillary lymph node dissection should not be abandoned when mandatory for prognostic purposes, considering that at present SN biopsy alone is not completely accurate for axillary staging, especially in the absence of an adequate learning period.

Adult↗
PubMedDate not supplied

Patients with Hashimoto's disease treated with L-thyroxine and followed for three years.

This study investigated the effectiveness of L-thyroxine management in 32 patients (mean age 11 years and 2 months; M:F = 1:5) with Hashimoto's disease followed annually for 3 years. One (8%) of the 12 patients, euthyroid at the onset, never required treatment; of the four (33%) who began treatment immediately, two were able to stop at the 1st or 2nd follow-up, whereas two had to continue. The other seven (59%) who did not begin treatment immediately had to start at the 1st, 2nd or 3rd follow-up. The findings in this small series suggest that hormone management may prove effective to a certain extent in euthyroid Hashimoto patients, primarily as a means of prevention.

Adolescent↗
PubMedDate not supplied

Factors at onset predictive of lasting remission in pediatric patients with Graves' disease followed for at least three years.

Seventeen pediatric patients (mean age at diagnosis 10 yr and 9 mo +/- 2 yr and 9 mo) with Graves' disease treated with 0.3-0.7 mg/kg/day methimazole and followed for at least three years, during which drug suspension was attempted on attainment of good clinical and metabolic compensation, were retrospectively studied to look for factors predictive of lasting remission present at onset. Lasting remission was defined as a clinical and laboratory picture of euthyroidism lasting at least one year in the absence of treatment at the end of the follow-up. A distinction was drawn between patients who reached remission after one or two courses (groups 1 and 2) and those who never attained a lasting remission (group 3). TRAb (TBIAb) levels at onset were the only factor significantly correlated with the response to treatment. Age at diagnosis, goiter size and fT3 and fT4 concentrations were not significantly correlated with the clinical picture. The series was too small to allow any assessment of the real importance of these factors, though a generally better response was displayed by children over 11 years old, without appreciable or with very small goiter and moderately increased thyroid hormone levels at onset (fT3 < 25 pg/ml in 10/10 in groups 1 and 2 and 2/7 in group 3 patients; fT4 < 40 pg/ml in 7/10 in groups 1 and 2 and 3/7 in group 3 patients). It was also found that better results were obtained when the initial drug course was protracted for at least two years.

Adolescent↗
PubMedDate not supplied

Correlation of drug response in human tumors histocultured in vitro with an image-analysis MTT end point and in vivo xenografted in nude mice.

We have in this study used the 3-(4,5-dimethyl-2- thiazoyl) -2,5-diphenyl 2-H-tetrazolium bromide (MTT) end point in our histoculture drug-response assay. We have previously demonstrated that the formazan crystals formed by MTT reduction by mitochondrial succinate dehydrogenase reflect polarized light and can be measured by pixel analysis in intact tissue. The results described here indicate a total specificity of 93.8% and a total accuracy of 74.6% of the MTT end point for drug response in histoculture correlating with nine different human xenograft tumors grown in nude mice with respect to the in vivo drug response data. This in vitro system allows prediction of positive and negative responses to drugs, with a rate of 70% and 71.8%, respectively. The system described here has potential for clinical use because of the possibility of simultaneous description of the MTT values and heterogeneous response to drugs within individual tumors.

Animals↗
PubMedDate not supplied

Intracellular accumulation and cytotoxic effect of (8-thiotheophyllinate) (triphenylphosphine) gold(I) in Friend leukemia cells.

Following continuous exposure to tTAuP in medium containing 10% fetal calf serum (FCS), cells resistant to doxorubicin (DOX-RFLC) were 3 fold more resistant to tTAuP than its sensitive counterpart (FLC). Moreover, FLC were 100 fold more sensitive to tTAuP when the cells were grown in the absence of FCS but in the presence of synthetic medium (BMS). When the cytotoxic effect was measured after short-term exposure (60 min) followed by 72 hr incubation in drug-free medium, unexpectedly, DOX-RFLC were 8 fold more sensitive [ID50 = 1.5 microM] than FLC [ID50 = 12 microM] to tTAuP. When FLC were exposed 60 min at different temperatures (4, 25 or 37 degrees C) to tTAuP prior to 72 hr incubation in drug free medium, the ID50 was achieved at 20, 13 and 3 microM respectively). In contrast, when DOX-RFLC were treated in similar conditions, the cytotoxic activity of tTAuP did not vary following exposure at 4, 25 or 37 degrees C. Although the mechanism of action of gold compounds is still unknown we have assumed that tTAuP cytotoxicity is related to the ease with which it is accumulated. This assumption was supported by the analysis of tTAuP incorporation by SXRF. The results reported here show that tTAuP accumulates rapidly in the cell and is distributed in the cytoplasmic and the nuclear fractions. It is suggested that accumulation is mediated by passive diffusion. However, the detection of gold binding to DNA in complexes resistant to solvent treatments suggests that interaction with macromolecules can be mediated by the formation of covalently bound complexes.

Animals↗
PubMedDate not supplied

Cytotoxic activity of azelaic acid against human melanoma primary cultures and established cell lines.

The in vitro cytotoxic activity of azelaic acid was studied with 25 human melanoma primary cultures and with 5 established cell lines characterized by different contents of melanotic pigment. A dose-dependent antiproliferative effect was observed in both the experimental systems, even though cell lines displayed a slightly greater susceptibility to the compound, with ID50 values generally lower than those for fresh human tumors. Our results do not demonstrate a clear difference between melanotic and non-melanotic melanomas in sensitivity to azelaic acid. The early interference of azelaic acid on nucleic acid metabolism was investigated additionally with 15 human melanoma primary cultures. There were significant inhibitions of RNA and DNA synthesis in a remarkable percentage of tumors, at the highest concentrations of the compound. Moreover, cell proliferation of tumors that showed these antimetabolic effects was always significantly depressed by lower drug concentration as well as by the highest.

Antineoplastic Agents↗
PubMedDate not supplied

Phase II study of alpha-interferon plus bleomycin in advanced non-small cell lung cancer.

A synergistic effect between alpha-Interferon and Bleomycin has been recently shown in in vitro and in vivo experimental systems. Although active, Bleomycin and other antineoplastic drugs give low response rates in non-small cell lung cancer, but, like the other antineoplastic agents, responses are short-lived. We treated 13 patients with advanced non-small cell lung cancer with the combination Bleomycin 15 mg/m2 i.v. at hour 0 and alpha-Interferon 9 X 10(6) U i.m. given at hours 6, 30 and 54. Major side effects were pyrexia, astenia and anorexia; only one case of moderate leukopenia was observed. No major responses were obtained and stable disease lasted a median of 5 months. Further study of this combination is not warranted in patients with pretreated non-small cell lung cancer.

Antineoplastic Combined Chemotherapy Protocols↗
PubMedDate not supplied

Positive interaction between interferon and bleomycin in vitro and in animal experimental models.

Effect of combined bleomycin and interferon on cell growth was evaluated in vitro, on 2 leukemia cell lines, and on mice bearing a murine leukemia. Human alpha-A interferon or murine alpha-beta interferon were used. Synergism was observed in both models and the sequence of administration was decisive in this respect. The in vivo results were not completely comparable with those observed in vitro. This finding suggests that the in vitro results reflect the direct effects of the drugs on tumor cells, meanwhile the interaction between drugs in vivo are affected by pharmacokinetic characteristics and by host defense systems.

Animals↗
PubMedDate not supplied

Induction of 2'-5' oligoadenylate synthetase and activation of ribonuclease in tamoxifen treated human breast cancer cell lines.

In the present study the intracellular activity of oligoadenylate synthetase and ribonuclease have been evaluated in two human breast cancer cell lines treated with tamoxifen, a well known antiestrogenic drug. Increased levels of oligoadenylate synthetase and enhanced ribonuclease activity have been found in the cultures of CG5 cell line treated with concentrations of tamoxifen inhibiting cell growth. In the experiments with the EVSA-T cell line we found neither an antiproliferative effect nor an increased oligoadenylate synthetase and ribonuclease activity. It is likely that these enzymes are involved in the mechanisms by which this drug acts as an antiproliferative agent.

2',5'-Oligoadenylate Synthetase↗
PubMedDate not supplied

Drug sensitivity tests after cell separation on density gradients.

Cells from two leukaemic cell lines (K562 and L1210) were separated on a discontinuous Percoll gradient with densities from 1040 to 1090 by centrifugation. The cells recovered from gradient interfaces were checked for their DNA content and subjected to two different drug sensitivity tests using three cytostatic drugs. The purpose of the study was to compare the sensitivity of a sample of the whole population with that of the fractions thus obtained. Depending on the test used and the line tested, there was a 5.5 to 55.5% discordance between the results for the fractions and the non-separated cells.

Animals↗