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Biomedical subjects

T Mariani

Publications and source records attributed to T Mariani.

At least 19 recordsLinked to original sources
PubMed2001

Scanning force images through the 'Milliscope'--a probe microscope with very wide scan range.

The effectiveness and adequacy of a home-built scanning force microscope (SFM) able to cover a volume of approximately 1.2 x 1.2 x 0.13 mm(3) (X x Y x Z) were tested on calibrating objects, as well as on cytological and histological samples. The instrument was designed for matching the magnification range of an optical microscope (approximately 20-1200x) but its dynamics were one or two orders of magnitude higher, thanks to a lateral resolution of about 10 nm. Images ranging in size from 1.2 x 1.2 mm(2) to 1 x 1 microm(2) showed a quality comparable to that given by other SFMs on similar materials. The 'Milliscope' is a curious but effective imaging tool whose operating range overlaps at one extreme with a goldsmith's eyepiece, and at the other with an electron microscope. The intrinsic limits of scanning probe techniques and of the available SFM cantilevers prevented us taking complete advantage of the wide height range of our scanner. However, our results show that an instrument having a very wide scan area, obtained through simple, inexpensive and intrinsically linear techniques, can give a good performance even at small scan sizes. This encourages us to develop wide scan instruments, which could further increase the already extensive use of scanning force microscopy in biology.

Humans↗
PubMed2000

Phase II trial of pyrazoloacridine in patients with cisplatin-refractory germ cell tumors.

Thirteen patients with cisplatin-refractory germ cell tumors were treated on a Phase II trial with pyrazoloacridine. Pyrazoloacridine was given intravenously at 600 mg/m2 every three weeks. The median nadir leucocyte count was 2.5 cells/mm3, hemoglobin was 10.8 g/dl, and platelet count was 126,000 cells/m3. None of the thirteen evaluable patients achieved a major response. Pyrazoloacridine is not efficacious in the treatment of cisplatin-refractory germ cell tumors.

Acridines↗
PubMed2000

Paclitaxel, ifosfamide, and cisplatin second-line therapy for patients with relapsed testicular germ cell cancer.

PURPOSE: To evaluate the dose, toxicity, and efficacy of paclitaxel in combination with ifosfamide and cisplatin as salvage therapy for patients with relapsed testicular germ cell tumors (GCTs). PATIENTS AND METHODS: Thirty patients with previously treated GCTs were treated with paclitaxel and ifosfamide plus cisplatin (TIP) as second-line therapy. All had favorable prognostic features for response (testis primary tumor site and prior complete response to first-line chemotherapy program). Four cycles of paclitaxel, ifosfamide 5 g/m(2), and cisplatin 100 mg/m(2) were given 21 days apart with granulocyte colony-stimulating factor support, followed by resection of radiographic residua. The dose of paclitaxel was increased among cohorts with dose levels of 175, 215, and 250 mg/m(2); the largest dose was selected for the phase II part of the trial. RESULTS: Twenty-three (77%) of 30 patients achieved a complete response to chemotherapy alone, and one patient achieved a durable partial response with normal tumor markers. Therefore, 24 (80%) achieved a favorable response. Eleven patients with normalized markers after chemotherapy underwent resection of residual tissue, with only necrosis found in 10 and mature teratoma in one. Two patients relapsed, and 22 (73%) of the favorable responses remain durable at a median follow-up duration of 33 months. Myelosuppression was the major toxicity, and two patients had grade 3 neurotoxicity. CONCLUSION: Four cycles of TIP was associated with a high proportion of patients who achieved a complete response, a lack of relapse, and relative tolerability as an ifosfamide-containing salvage regimen for testicular GCTs. The high durable complete response proportion emphasizes the importance of patient selection according to prognostic factors for a favorable outcome to conventional-dose salvage therapy.

Adult↗
PubMed2000

Phase III trial of interferon alfa-2a with or without 13-cis-retinoic acid for patients with advanced renal cell carcinoma.

PURPOSE: A randomized phase III trial was conducted to determine whether combination therapy with 13-cis-retinoic acid (13-CRA) plus interferon alfa-2a (IFNalpha2a) is superior to IFNalpha2a alone in patients with advanced renal cell carcinoma (RCC). PATIENTS AND METHODS: Two hundred eighty-four patients were randomized to treatment with IFNalpha2a plus 13-CRA or treatment with IFNalpha2a alone. IFNalpha2a was given daily subcutaneously, starting at a dose of 3 million units (MU). The dose was escalated every 7 days from 3 to 9 MU (by increments of 3 MU), unless >/= grade 2 toxicity occurred, in which case dose escalation was stopped. Patients randomized to combination therapy were given oral 13-CRA 1 mg/kg/d plus IFNalpha2a. Quality of life (QOL) was assessed. RESULTS: Complete or partial responses were achieved by 12% of patients treated with IFNalpha2a plus 13-CRA and 6% of patients treated with IFNalpha2a (P =.14). Median duration of response (complete and partial combined) in the group treated with the combination was 33 months (range, 9 to 50 months), versus 22 months (range, 5 to 38 months) for the second group (P =.03). Nineteen percent of patients treated with IFNalpha2a plus 13-CRA were progression-free at 24 months, compared with 10% of patients treated with IFNalpha2a alone (P =.05). Median survival time for all patients was 15 months, with no difference in survival between the two treatment arms (P =.26). QOL decreased during the first 8 weeks of treatment, and a partial recovery followed. Lower scores were associated with the combination therapy. CONCLUSION: Response proportion and survival did not improve significantly with the addition of 13-CRA to IFNalpha2a therapy in patients with advanced RCC. 13-CRA may lengthen response to IFNalpha2a therapy in patients with IFNalpha2a-sensitive tumors. Treatment, particularly the combination therapy, was associated with a decrease in QOL.

Administration, Oral↗
PubMed2000

Sequential dose-intensive paclitaxel, ifosfamide, carboplatin, and etoposide salvage therapy for germ cell tumor patients.

PURPOSE: To evaluate the efficacy and toxicity of sequential, dose-intensified chemotherapy with paclitaxel/ifosfamide and carboplatin/etoposide administered plus peripheral blood-derived stem-cell (PBSC) support for patients with germ cell tumors (GCT) who have unfavorable prognostic features in response to conventional-dose salvage programs. Carboplatin was dose escalated by target area under the curve (AUC; in [milligrams per milliliter] x minutes) among patient cohorts, and pharmacokinetic studies were performed for comparison. PATIENTS AND METHODS: Thirty-seven previously treated patients who had cisplatin-resistant GCT and unfavorable prognostic features for response to conventional-dose salvage therapy were treated. Two cycles of paclitaxel 200 mg/m(2) plus ifosfamide 6 g/m(2) were given 2 weeks apart with leukapheresis, followed by three cycles of carboplatin plus etoposide given 14 to 21 days apart with reinfusion of PBSCs. The dose of etoposide was 1, 200 mg/m(2), and the carboplatin target AUC ranged among cohorts from 12 to 32 (mg/mL) x min. Pharmacokinetic studies of carboplatin were performed for comparison of target to measured AUC. RESULTS: Twenty-one patients (57%) achieved a complete response and an additional two patients (5%) achieved a partial response with normal tumor markers; therefore, 23 (62%) achieved a favorable response. Eight patients relapsed, and 15 (41%) of the favorable responses remained durable at a median follow-up of 30 months. Myelosuppression was the major toxicity; 58% of carboplatin/etoposide cycles were associated with hospitalization for nadir fever. The AUC of carboplatin measured in serum was lower than the target AUC; this may be related to underestimation of the glomerular filtration rate used in the dosing formula. CONCLUSION: Dose-intense therapy with sequential, accelerated chemotherapy of paclitaxel/ifosfamide and carboplatin/etoposide administered with PBSC support was relatively well tolerated. The durable complete response proportion was substantial in patients with unfavorable prognostic features for achieving durable complete response to conventional-dose salvage programs. Optimal dosing of carboplatin in the high-dose setting warrants further investigation.

Adolescent↗
PubMed1997

Atomic force microscope imaging of chromosome structure during G-banding treatments.

Surface topography of human chromosomes was examined by atomic force microscopy during treatments for G-banding. Trypsin treatment resulted in a structural modification in the chromatin. Subsequent Giemsa staining caused a general swelling of the chromosomal surface that was greater in the areas of G-band positive regions. By means of a quantitative evaluation method we showed that the G-banding process produces a 10-fold enhancement of a pre-existing pattern of chromatin between G-band positive and G-band negative regions on mitotic chromosomes.

Azure Stains↗
PubMed1995

No statistical association between fragile sites and constitutional chromosome breakpoints.

Ten thousand four hundred ninety-two constitutional breakpoints available from the cytogenetic literature were analyzed for their coincidence with known fragile sites (FS) at 303-band resolution. In this analysis we have taken into account the stochastic connections of some features of chromosome bands with both the presence of FS and constitutional breakage. Our results suggest that there is no particular association between FS and constitutional chromosome rearrangements.

Chromosome Aberrations↗
PubMed1994

Longitudinal patterns similar to G-banding in untreated human chromosomes: evidence from atomic force microscopy.

The structure of human metaphase chromosomes, fixed according to standard procedures for optical microscopy but not treated for banding, was examined by atomic force microscopy (AFM). The images show that chromosomes display a banding pattern very similar to G-banding, detected by the AFM as a variation in the thickness of chromatin. This similarity allows the identification of individual chromosomes.

Chromatin↗
PubMed1994

An atomic force microscope for cytological and histological investigations.

An atomic force microscope (AFM) specifically designed for cytological and histological studies and able to operate on the same scale of the highest optical magnification is described. The AFM is a non-invasive instrument; it operates on samples which do not require any kind of treatment and it can produce information that supplements and completes the information given by traditional microscopical methods. The apparatus has been used to image fixed human chromosomes and to investigate the action of trypsin during the staining for banding. First results showed that banding patterns very similar to G-banding pre-exist to staining and to trypsin treatment in human metaphase chromosomes, and that the trypsin treatment induces a structural collapse in the chromatin. The instrument was also used on thin sections of plant tissue and gave promising results. Experience confirmed that AFM is a suitable tool for this kind of investigation, and proved the importance of developing AFM microscopes specifically designed for routine use in cytology and histology, conceived for non-specialized users.

Chromosome Banding↗
PubMed1993

Analysis of electroporation-induced genetic damages in V79/AP4 Chinese hamster cells.

Electroporation is a recent technique used to introduce exogenous DNA into eukaryotic cells. It is important to establish that the gene of interest is transferred into a functional, non-mutated recipient cell. V79/AP4 Chinese hamster cells were exposed to high-voltage pulsed electric fields and some biological and genetic effects were measured. The results showed that cytotoxicity was related in a dose-dependent manner to the number of applied pulses. Thioguanine-resistant colony-forming cells as well as chromosomal aberrations were also induced whereas ouabain resistants and sister-chromatid exchanges were not or slightly induced. Spontaneous and electroporation-induced clones that were phenotypically TGR/HATS were used to investigate the hprt locus. Molecular screening of the locus showed that the number of deleted exons was significantly higher in induced than in spontaneous TG-resistant clones, suggesting that the genetic damages induced by electroporation concern the loss of regions well over the size of the hprt locus.

Animals↗
PubMed1993

Accumulation of anchorage independent cells showing amplified genes (CAD) during the in vitro propagation of CHEF18 Chinese hamster cells.

Anchorage independence and gene amplification have frequently been associated with a transformed or tumorigenic phenotype in cultured mammalian cells. However, it is unknown whether these two traits occur as related events during transformation, or are independent features of the transformed phenotype. To clarify this point, immortalized, untransformed CHEF18 Chinese hamster cells were propagated in culture until they became transformed and tumorigenic. The frequencies with which CHEF18 cells formed colonies either in soft agar, in medium containing N-phosphonacetyl-L-aspartate or in the two selective media simultaneously, were determined. The results indicate that anchorage independence and CAD gene amplification spontaneously arose during the propagation of the cells and that their concurrent emergence was not the consequence of independent events. However, the kinetics of their appearance suggests that anchorage independence is the early event whereas gene amplification might represent one of the numerous events which can be dynamically selected in anchorage-independent cells.

Animals↗
PubMed1992

Responsiveness of tumorigenic and non-tumorigenic CHEF18 Chinese hamster cells to 1-beta-D-arabinofuranosylcytosine treatment.

In cultured mammalian cells, sister chromatid exchanges are easily induced by agents that perturb the scheduled timing of DNA replication. In this work a blockage of DNA synthesis induced by 1-beta-D-arabinofuranosylcytosine was applied to non-tumorigenic and tumorigenic CHEF18 Chinese hamster cells, and their responsiveness was compared. The data show that both the induction of sister chromatid exchanges and the reduction of the colony-forming ability were less extensive in non-tumorigenic than in tumorigenic CHEF18 cells. The results suggest that a tight control of the scheduled timing of DNA replication is present in non-tumorigenic CHEF18 cells and perhaps this feature avoids the generation of those chromosomal structures that are responsible for the abnormal induction of sister chromatid exchanges and for the elevated cytotoxicity seen in tumorigenic cells.

Animals↗
PubMed1990

Folate-sensitive fragile sites in Chinese hamster cell lines.

The expression of fragile sites in three different Chinese hamster cell lines was studied. Results showed that folate-sensitive fragile sites were expressed in the pericentromeric regions of chromosomes 1, 3, 4, 6, and 7 and in band 1q22. A comparison of the breakpoints involved in formation of chromosome rearrangements in some established Chinese hamster cell lines was also made. Results showed that while the specific type of rearrangement was random, the breakpoints were not. Three of the chromosomal sites most frequently involved in breaks were regions in which fragile sites were expressed.

Animals↗
PubMed1989

Fragile sites and statistics.

A simple and reliable statistical method is proposed to distinguish real fragile sites from the casual accumulation of aberrations that can occur as a consequence of random distribution. It is based on a study of the expected random distribution, assumed to be equal to a Poisson distribution, with the expected value of events per band as the mean.

Chromosome Fragile Sites↗
PubMed1989

The distribution patterns of sister chromatid exchanges in V79 Chinese hamster cells: relevance to genotoxicity studies.

Sister chromatid exchanges (SCEs) are routinely used in genotoxic studies. The observations that some agents induce SCEs without altering the SCE distribution, while others disrupt such distribution, support the use of SCE distribution as a tool to distinguish between agents which damage DNA and agents which interfere with the replication machinery. In addition to that, it was found that compounds belonging to the latter group, are also able to induce gene amplification. Despite the mechanism by which the two phenomena could be associated is undefined, an aberrant induction of SCEs as a basis of gene amplification it must be taken into account.

Animals↗
PubMed1988

Qualitative analysis of chromosomal evolution in a colcemid-treated Chinese hamster population.

Colcemid is known to inhibit the spindle formation and to induce polyploidy and chromosomal nondisjunction. Using a V79 Chinese hamster cell line, we have shown that colcemid is able to induce the formation of cells that are numerically diploid but whose karyotype, when analyzed with the G-banding technique, differs from that of the untreated ones. Even though these cells have a normal chromosomal constitution, they carry alterations in the chromosomal balance and, consequently, in gene dosage. This could result in an abnormal expression of cellular genes or in the expression of new or preexisting recessive mutations, even in a diploid chromosomal constitution.

Aneuploidy↗
PubMed1988

Gene dosage mutants at adenine phosphoribosyltransferase locus induced by colcemid in Chinese hamster V79-AP4 cells.

Pseudodiploid Chinese hamster V79-AP4 cells, functionally diploid at the adenine phosphoribosyltransferase (aprt) locus, were treated with colcemid, a well-known aneuploidizing agent, under various experimental conditions. Aneuploid and tetraploid cells and variants resistant to 10 micrograms/ml of 2,6-diaminopurine (DAP), which selects for presumptive aprt+/- heterozygotes in the untreated cells, were induced. Many of the induced variants were hypotetraploid with three (rather than four) chromosomes carrying the aprt gene. Dot-blot and Southern analysis of the DNA of these clones confirmed that they had three copies of the aprt gene. Their APRT specific enzymatic activity was 60-80% of that of wild-type V79-AP4. The results of these and other experiments suggest that in these variants resistance to DAP is due to an altered aprt gene dosage and point to a possible genetic effect of colcemid and other aneuploidizing agents in somatic mammalian cells.

2-Aminopurine↗