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T Mazzei

Publications and source records attributed to T Mazzei.

At least 19 recordsLinked to original sources
PubMed2006

Cellular pharmacology of gemcitabine.

Gemcitabine (2',2'-difluoro 2'-deoxycytidine, dFdC) is the most important cytidine analogue developed since cytosine arabinoside (Ara-C). The evidence of its potent antitumor activity in a wide spectrum of in vitro and in vivo tumor models has been successfully confirmed in the clinical setting. Despite structural and pharmacological similarities to Ara-C, gemcitabine displays distinctive features of cellular pharmacology, metabolism and mechanism of action. Following influx through the cell membrane via nucleoside transporters, gemcitabine undergoes complex intracellular conversion to the nucleotides gemcitabine diphosphate (dFdCDP) and triphosphate (dFdCTP) responsible for its cytotoxic actions. The cytotoxic activity of gemcitabine may be the result of several actions on DNA synthesis. dFdCTP competes with deoxycytidine triphosphate (dCTP) as an inhibitor of DNA polymerase. dFdCDP is a potent inhibitor of ribonucleoside reductase, resulting in depletion of deoxyribonucleotide pools necessary for DNA synthesis and, thereby potentiating the effects of dFdCTP. dFdCTP is incorporated into DNA and after the incorporation of one more nucleotide leads to DNA strand termination. This extra nucleotide may be important in hiding the dFdCTP from DNA repair enzymes, as incorporation of dFdCTP into DNA appears to be resistant to the normal mechanisms of DNA repair. Gemcitabine can be effectively inactivated mainly by the action of deoxycytidine deaminase to 2,2'-difluorodeoxyuridine. Also, 5'-nucleotidase opposes the action of nucleoside kinases by catalysing the conversion of nucleotides back to nucleosides. Additional sites of action and self-potentiating effects have been described. Evidence that up- or down-regulation of the multiple membrane transporters, target enzymes, enzymes involved in the metabolism of gemcitabine and alterations in the apoptotic pathways may confer sensitivity/resistance to this drug, has been provided in experimental models and more recently also in the clinical setting. Synergism between gemcitabine and several other antineoplastic agents has been demonstrated in experimental models based on specific pharmacodynamic interactions. Knowledge of gemcitabine cellular pharmacology and its molecular mechanisms of resistance and drug interaction may thus be pivotal to a more rational clinical use of this drug in combination regimens and in tailored therapy.

Antimetabolites, Antineoplastic↗
PubMed2005

Intraoperative positive fluid balance improves tissue diffusion of ceftizoxime.

AIM OF STUDY: To demonstrate that administration of fluids and the consequent improvement of fluid balance during a surgical procedure can modify the tissue diffusion of ceftizoxime. METHODS: Twenty-eight patients (30-79 years) undergoing major abdominal surgery of the colon were administered ceftizoxime 30 mg/kg i.v. at induction of anesthesia. A sample of arterial blood was taken before administration of the drug (t0) and then again at the time of vascular occlusion of the colon segment to be removed (t1). A sample of the segment of removed colon was taken. The patients were divided into two groups on the basis of the fluid balance between t0 and t1: group A (n = 17) with a fluid balance <1,000 ml and group B (n = 11) with a fluid balance >1,000 ml. The parameters evaluated in each group were: weight, height and age of the patients, serum and tissue antibiotic concentration, percent ratio of serum and tissue concentration, time elapsed between t0 and t1, volume of administered fluids between t0 and t1, diuresis and hourly diuresis between t0 and t1 and body fluid distribution, obtained using a bioelectrical impedance analyzer. The mean results obtained in the two groups were then compared using Student's t test. RESULTS: The balance of fluids calculated up to t1 was 675 +/- 308 ml for group A and 1,411 +/- 405 ml for group B (p < 0.01). The means of the recorded values that showed statistically significant differences were: mean percent concentration ratio (43.6 +/- 8.4 vs. 84 +/- 16%; p < 0.05), concentration in the colonic segment (16.3 +/- 7.9 vs. 37.2 +/- 25.9 mg/ml; p < 0.05), urinary volume gathered up to t1 (538 +/- 557 vs. 169 +/- 104 ml; p < 0.05), hourly urinary volume up to t1 (311.1 +/- 296 vs. 97.6 +/- 77.9 ml/h; p < 0.05), percent variation of resistance (95.1 +/- 5.1 vs. 89.7 +/- 8.6; p < 0.05). The other means did not show any significant statistical differences. CONCLUSIONS: A higher tissue water level seems to facilitate the penetration of the antibiotic into the tissue according to the pharmacokinetic characteristics of ceftizoxime: high amount of free drug (not bound to plasma proteins) and high hydrosolubility.

Adult↗
PubMed2002

Amoxicillin/clavulanic acid versus cefotaxime for antimicrobial prophylaxis in abdominal surgery: a randomized trial.

Amoxicillin/clavulanic acid (amoxicillin 2 g/clavulanic acid 200 mg) has been administered in comparison to cefotaxime (2 g) for antimicrobial prophylaxis in 476 evaluable patients undergoing abdominal surgery at high risk of septic complications. Both antibiotics were administered as a single infusion. 205 evaluable patients (110 in amoxicillin/clavulanic acid group and 95 in cefotaxime group) underwent upper gastrointestinal surgery (including gastroduodenal and biliary surgery). The wound infection rate was 4.5% for amoxicillin/clavulanic acid and 7.4% for cefotaxime, with no significant differences. Intra-abdominal abscesses were observed in 3 patients in the amoxicillin/clavulanic acid group and in 1 patient in the cefotaxime group. 271 evaluable patients (135 in amoxicillin/clavulanic acid group and 136 in cefotaxime group) underwent lower gastrointestinal surgery (including colorectal surgery). The wound infection rate was 11% for amoxicillin/clavulanic acid and 13% for cefotaxime, with no significant differences. A purulent discharge was present in 3 patients in both groups. Intra-abdominal abscesses were observed in 3 patients in the amoxicillin/clavulanic acid group and in 4 patients in the cefotaxime group. No serious adverse events and no cases of diarrhea were observed. In conclusion, in our experience amoxicillin/clavulanic acid proved to be as effective as cefotaxime in protecting patients from surgical infections in abdominal surgery. Its use in surgical prophylaxis may help decrease the cost of treatment and reduce the risk of resistance to antibiotics and superinfections.

Abdomen↗
PubMed2002

In vivo pharmacodynamic evaluation of clarithromycin in comparison to erythromycin.

The efficacy of various dosing regimens of clarithromycin and erythromycin against recently isolated Streptococcus pneumoniae strains was determined in vivo using two animal infection models (mouse peritonitis and thigh infection). For the thigh infection model, mice received a total dose of 4 mg/Kg of either clarithromycin or erythromycin, as a single total dose or divided into 2, 4 or 8 doses/24h. After 24h of therapy S. pneumoniae organisms were killed at 2.06 to 4.03 log10 CFU/thigh by clarithromycin and the one- or two-dose regimens were significantly more effective than the four- or eight-dose regimens. Organism killing following 24h of therapy with erythromycin ranged from 1.13 to 2.31 log10 CFU/thigh, with the one- or two-dose regimens significantly less effective than the four- or eight-dose regimens. In the mouse survival study, the same dose of either clarithromycin or erythromycin was given as a single total dose or divided into two or four doses with dosing intervals of 4 and 2-times the t1/2 respectively. The results obtained in this model show that there is a significant difference in survival when clarithromycin is administered less frequently (4% deaths for the one-dose regimen in comparison to 40% deaths with the four-dose regimen, P < 0.01, Chi-square test). With erythromycin there was a trend for increased survival with the multiple-dose regimen, with significantly higher survival when concentrations exceeding the MIC were maintained for a longer time period. These results indicate that the time during which serum concentrations exceeding the MIC value of the pathogen is an important parameter for efficacy for erythromycin. On the contrary, results with both animal models demonstrate that bacterial killing and survival are significantly higher among clarithromycin-treated mice when the antibiotic is administered less frequently and the highest Cmax/MIC ratio is achieved.

Animals↗
PubMed2001

Oxaliplatin and protracted continuous 5-fluorouracil infusion in patients with pretreated advanced colorectal carcinoma.

BACKGROUND: Both OHP and 5-FU are clinically active as single agents in the treatment of metastatic colorectal cancer (MCRC). Clinical and laboratory studies suggest a synergistic interaction between these agents. This phase II study was performed to evaluate the activity of a schedule including OHP and protracted 5-FU infusion in 5-FU-resistant MCRC. PATIENTS AND METHODS: From October 1997 to January 2000, 50 patients with measurable progressive MCRC after one or more 5-FU-based regimens were treated. OHP (2-3-hour i.v. infusion) on day 1 and 5-FU (protracted i.v. infusion using elastomeric/electronic pump through a central venous catheter) on days 1-21 were administered every 3 weeks, at the following 4 dose levels: 1) OHP 100 mg/m2 + 5-FU 200 mg/m2 (21 patients); 2) OHP 100 mg/m2 + 5-FU 250 mg/m2 (3 patients); 3) OHP 130 mg/m2 + 5-FU 200 mg/m2 (10 patients); 4) OHP 130 mg/m2 + 5-FU 250 mg/m2 (6 patients). RESULTS: Objective responses were 1 (2%) CR; 10 (20%) PR, for a median duration of 8 months; 23 (46%) stable diseases, for a median duration of 6 months: 16 (32%) progressions. CR + PR was higher in patients who had previously received no more than one line of chemotherapy for metastatic disease as compared with patients who had received two or more lines of therapy (33% vs. 5%, P < 0.01). The median time to progression was four months (one to nine). All dose levels (313 cycles) were well tolerated with mild toxicity. Major toxicity (grade 3 WHO) included: anaemia in 1 patient (2%), nausea and vomiting in 1 patient (2%), diarrhoea in 4 patients (8%) and stomatitis in 1 patient (2%); grade I and 2 peripheral neuropathy were encountered, respectively, in 30 (60%) and 8 (16%) patients. The median survival was 13 months (9-17), with 32 patients still alive after a median follow-up of 8 months. CONCLUSIONS: This study suggests that 1) OHP plus protracted 5-FU infusion is an active combination in MCRC patients resistant to pre-treatment bolus 5-FU; 2) it has a good tolerability profile and 3) the optimum dose level is OHP 130 mg/m2 and 5-FU 250 mg/m2.

Adult↗
PubMed2001

Amoxicillin/clavulanate in chronic rhinosinusitis: tissue and serum distribution.

UNLABELLED: Amoxicillin/clavulanate in chronic rhinosinusitis: tissue and serum distribution. OBJECTIVE: The aim of the present study is to determine the concentrations of coamoxiclav in the sinusal mucosa of patients undergoing surgery for chronic sinusitis in comparison to serum levels after single oral administration. METHODOLOGY: 24 patients affected by chronic sinusitis, undergoing sinus surgery, were divided into three groups receiving an oral dose of 1 g of coamoxiclav (875 mg amoxicillin, 125 g of clavulanic acid, 7:1 ratio) at 2 h (first group), 4 h (second group) and 6 h (third group) before surgery. The mean concentration of amoxicillin and clavulanic acid were determined biologically in serum and in tissues. RESULTS: The highest concentrations of coamoxiclav both in serum and tissues were observed in the group which received the antibiotic 2 hours before surgery. However the tissue levels of both amoxicillin and clavulanic acid in the time period within 2-6 h after administration were higher than the Minimum Inhibitory Concentration (MIC) for the most frequent causative pathogens of sinus bacterial infections. CONCLUSIONS: Since penicillins need to maintain concentrations above the MIC for at least 40 to 60% of the interval time between administrations to be potentially effective, the Authors concluded that since both amoxicillin and clavulanic acid spread well in the ENT tissues, 1 g twice a day of the combination seems to be clinically effective even in patients suffering from acute episodes of chronic rhinosinusitis.

Adolescent↗
PubMed2001

[Role of parenteral cephalosporins for outpatients treatment of infections].

OPAT (Outpatient Parenteral Antibiotic Therapy) arose in the early 1980s in the USA and later in many other countries from the primary consideration that outpatient treatment is more cost-effective than hospitalisation. Currently, several thousand patients undergo OPAT programmes all over the world and several different bacterial infections are included in the list of treatable diseases, especially those requiring long-term parenteral treatment such as osteomyelitis and soft tissue infections. All injectable antibiotics are suitable for OPAT according to their microbiological spectrum, although clearly some pharmacological properties make one antibiotic more preferable than another. Beta-lactams represent more than half of the antibiotic world market and two-thirds of them are cephalosporins. Such a widespread use of cephalosporins is certainly due to their wide antibacterial spectrum and good tolerability. Among third-generation cephalosporins, covering the majority of micro-organisms responsible for community-acquired infections, ceftriaxone is the only one with an 8-hour half-life, thereby permitting a single daily dose, which represents a great advantage when undertaking an OPAT programme. Analysis of antibiotic consumption used for OPAT therapies, based on data collected from the International OPAT Registry project, with the participation of many countries (USA, Canada, Britain, Argentina, etc.) including Italy, shows that ceftriaxone is the most widely used antibiotic for home therapy, clearly due to the above-mentioned properties.

Ambulatory Care↗
PubMed2000

Gold(III) complexes as potential antitumor agents: solution chemistry and cytotoxic properties of some selected gold(III) compounds.

Gold(III) complexes generally exhibit interesting cytotoxic and antitumor properties, but until now, their development has been heavily hampered by their poor stability under physiological conditions. To enhance the stability of the gold(III) center, we prepared a number of gold(III) complexes with multidentate ligands - namely [Au(en)(2)]Cl(3), [Au(dien)Cl]Cl(2), [Au(cyclam)](ClO(4))(2)Cl, [Au(terpy)Cl]Cl(2), and [Au(phen)Cl(2)]Cl - and analyzed their behavior in solution. The solution properties of these complexes were monitored by visible absorption spectroscopy, mass spectrometry, and chloride-selective potentiometric measurements; the electrochemical properties were also studied by cyclic voltammetry and coulometry. Since all the investigated compounds exhibited sufficient stability under physiological conditions, their cytotoxic properties were tested in vitro, via the sulforhodamine B assay, on the representative human ovarian tumor cell line A2780, either sensitive or resistant to cisplatin. In most cases the investigated compounds showed relevant cell-killing properties with IC(50) values falling in the 0.2-10 microM range; noticeably most investigated gold(III) complexes were able to overcome, to a large extent, resistance to cisplatin when tested on the corresponding cisplatin-resistant cell line. The cytotoxic properties of the free ligands were also determined under the same solution conditions. Ethylenediamine, diethylenetriamine, and cyclam were virtually nontoxic (IC(50) values > 100 microM) so that the relevant cytotoxic effects observed for [Au(en)(2)]Cl(3) and [Au(dien)Cl]Cl(2) could be quite unambiguously ascribed to the presence of the gold(III) center. In contrast the phenanthroline and terpyridine ligands turned out to be even more cytotoxic than the corresponding gold(III) complexes rendering the interpretation of the cytotoxicity profiles of the latter complexes less straightforward. The implications of the present findings for the development of novel gold(III) complexes as possible cytotoxic and antitumor drugs are discussed.

Antineoplastic Agents↗
PubMed2000

Cytotoxicity and DNA binding properties of a chloro glycylhistidinate gold(III) complex (GHAu).

The chloro glycylhistidinate gold(III) complex (GHAu) is shown to be fairly cytotoxic towards the established A2780 ovarian carcinoma human cell line either sensitive or resistant to cisplatin. Remarkably, GHAu is far more cytotoxic than the corresponding zinc(II), palladium(II), platinum(II) and cobalt(II) complexes implying that cytotoxicity is essentially to be ascribed to the presence of a gold(III) center. Circular dichroism (CD) spectra, atomic absorption measurements and DNA melting profiles suggest that GHAu in vitro is able to bind DNA, the presumed target for several antitumor metal complexes, and to modify its conformation, even if the observed changes are generally small. Implications of these findings for the mechanism of action of cytotoxic gold(III) complexes are discussed.

Animals↗
PubMed2000

Granisetron, tropisetron, and ondansetron in the prevention of acute emesis induced by a combination of cisplatin-Adriamycin and by high-dose ifosfamide delivered in multiple-day continuous infusions.

The antiemetic efficacy of granisetron, ondansetron and tropisetron was evaluated in patients treated with cisplatin-Adriamycin (CDP/ADM) and ifosfamide (IFO) by continuous infusion (CI). In all, 90 patients with osteosarcoma were randomly assigned to receive granisetron (2 mg/m2), or ondansetron (5.3 mg/m2), or tropisetron (3.3 mg/m2) plus dexamethasone 8 mg/m2. Chemotherapy consisted of CDP (120 mg/m2, 48-h CI) followed by ADM (75 mg/m2, 24-h CI) and then, in the second cycle, delivered 3 weeks later, IFO 15 g/m2 (120-h CI). Complete protection (CP) from emesis was obtained on 59% of the 717 days of treatment, without significant differences among the three study drugs. A significantly higher rate of CP was obtained during chemotherapy with IFO than with CDP/ ADM (69% vs 44%; P<0.0001). The rate of CP declined from the first to the last day of treatment for both CDP/ADM (61% to 27%, P<0.0001) and IFO (95% to 43%) cycles (P<0.0001). When CDP/ ADM and IFO are delivered on multiple days by CI, granisetron, ondansetron and tropisetron have the same antiemetic efficacy, which declines from the first day onward through successive days.

Acute Disease↗
PubMed2000

Modulation of dihydrofolate reductase gene expression in methotrexate-resistant human leukemia CCRF-CEM/E cells by antisense oligonucleotides.

An increase in the cellular levels of dihydrofolate reductase (DHFR) is one of the most common mechanisms of tumor resistance to methotrexate (MTX), an antimetabolite that is widely used in the treatment of a variety of human malignancies. The MTX-resistant phenotype generally occurs as a consequence of DHFR gene amplification which in turn is responsible for DHFR gene overexpression. We have designed antisense oligodeoxynucleotides (aODNs) against the DHFR mRNA and tested their in vitro effect on human leukemia CCRF-CEM/E cells, overexpressing the DHFR gene about 20-fold in comparison with the CCRF-CEM/S parental cell line. An aODN complementary to a region encompassing the AUG translation start (DHFR1) of DHFR mRNA and a mixture of two aODNs complementary to the 5' untranslated region (DHFR2+DHFR3) have been used. A DHFR1 scrambled-sequence ODN and a fully degenerated ODN were the controls. All ODNs had a phosphodiester backbone. DHFR1 and the relevant scrambled ODN were also capped with two phosphorothioate derivatives at both the 5' and 3' ends in order to increase ODN stability against serum nucleases. ODNs were vehiculated with a cationic lipid, N-[1-(dioleoyloxy)propyl]-N,N,N-trimethylammonium methyl sulfate (DOTAP), known to enhance ODN cell uptake and biological activity. The effects of ODNs on DHFR gene expression were studied after a 4 day treatment by measuring both DHFR mRNA levels, using a semi-quantitative reverse transcription polymerase chain reaction method, and DHFR protein levels by flow cytometry. A marked reduction in DHFR mRNA levels (79.7 and 74.2%, respectively) was observed with both DHFR1 and DHFR2+DHFR3 aODNs, associated with a lower decrease in DHFR enzyme (44.8 and 61%, respectively). aODN effects on MTX cytotoxicity in CCRF-CEM/E cells were also assessed. No marked enhancement of in vitro MTX cytotoxicity was observed following co-exposure of cells with aODNs and the tested concentrations of the antifol (0.05 and 0.5 microM), indicating that no substantial reversal of the MTX-resistant phenotype was induced by the study aODNs.

DNA Primers↗
PubMed2000

Postantibiotic leukocyte enhancement of meropenem against gram-positive and gram-negative strains.

The postantibiotic leukocyte enhancement (PALE) of meropenem in vitro in comparison with that of imipenem was evaluated with 24 recently isolated gram-positive and gram-negative strains. In general, pre-exposure to carbapenems (at four times the MIC for 2 h) led to increased polymorphonuclear cell phagocytic killing. The PALE of imipenem was generally significantly less than that observed with meropenem.

Anti-Bacterial Agents↗
PubMed2000

Interactions between triazoles and amphotericin B against Cryptococcus neoformans.

The interaction of amphotericin B (AmB) and azole antifungal agents in the treatment of fungal infections is still a controversial issue. A checkerboard titration broth microdilution-based method that adhered to the recommendations of the National Committee for Clinical Laboratory Standards was applied to study the in vitro interactions of AmB with fluconazole (FLC), itraconazole (ITC), and the new investigational triazole SCH 56592 (SCH) against 15 clinical isolates of Cryptococcus neoformans. Synergy, defined as a fractional inhibitory concentration (FIC) index of < or =0.50, was observed for 7% of the isolates in studies of the interactions of both FLC-AmB and ITC-AmB and for 33% of the isolates in studies of the SCH-AmB interactions; additivism (FICs, >0.50 to 1.0) was observed for 67, 73, and 53% of the isolates in studies of the FLC-AmB, ITC-AmB, and SCH-AmB interactions, respectively; indifference (FICs, >1.0 to < or =2.0) was observed for 26, 20, and 14% of the isolates in studies of the FLC-AmB, ITC-AmB, and SCH-AmB interactions, respectively. Antagonism (FIC >2.0) was not observed. When synergy was not achieved, there was still a decrease, although not as dramatic, in the MIC of one or both drugs when they were used in combination. To investigate the effects of FLC-AmB combination therapy in vivo, we established an experimental model of systemic cryptococcosis in BALB/c mice by intravenous injection of cells of C. neoformans 2337, a clinical isolate belonging to serotype D against which the combination of FLC and AmB yielded an additive interaction in vitro. Both survival and tissue burden studies showed that combination therapy was more effective than FLC alone and that combination therapy was at least as effective as AmB given as a single drug. On the other hand, when cells of C. neoformans 2337 were grown in FLC-containing medium, a pronounced increase in resistance to subsequent exposures to AmB was observed. In particular, killing experiments conducted with nonreplicating cells showed that preexposure to FLC abolished the fungicidal activity of the polyene. However, this apparent antagonism was not observed in vivo. Rather, when the two drugs were used sequentially for the treatment of systemic murine cryptococcosis, a reciprocal potentiation was often observed. Our study shows that (i) the combination of triazoles and AmB is significantly more active than either drug alone against C. neoformans in vitro and (ii) the concomitant or sequential use of FLC and AmB for the treatment of systemic murine cryptococcosis results in a positive interaction.

Amphotericin B↗
PubMed2000

New insight into the clinical pharmacokinetics of cefaclor: tissue penetration.

The serum pharmacokinetic data presented are generally in agreement with those obtained by other authors with both the cefaclor IR (immediate release) and AF (advanced formulation) or MR (modified release) formulations. With the new sustained-release formulation, the time of peak (Tmax) and mean residence time (MRT) values are significantly longer than those observed with the standard cefaclor IR. For the first time the penetration of the MR formulation of cefaclor was determined both in suction blister fluid (SBF) and alveolar epithelial lining fluid (ELF). Cefaclor demonstrated a high tissue distribution, with a high penetration index (PI) into blister fluid, which is at least representative of a relatively large volume of fluid-filled spaces and in part of highly vascularized tissues. SBF and ELF concentrations were higher than blood levels starting at the 4th-6th hour after dose, with longer elimination half-lives from the extravascular compartment than from serum. Cefaclor has a favorable pharmacokinetic profile, especially the new sustained-release formulation, which maintains effective concentrations for a longer time than the IR preparation. The MR formulation improves the kinetic properties of the cefaclor molecule with a prolonged MRT which allows a daily dosage of 750 mg every 12 h.

Aged↗
PubMed2000

Cefodizime in skin suction blister fluid and serum following a single intravenous or intramuscular dose in adult patients.

Cefodizime is a third generation cephalosporin for parenteral use. The pharmacokinetics of this cephem antibiotic were determined in serum and skin suction blister fluid (SBF) after intravenous (i.v.) or intramuscular (i.m.) administration of a single 1 g dose in 8 adult patients with normal renal and hepatic function who volunteered for the study. The concentration versus time curve showed a slower elimination rate from the extravascular compartment: the half-lives were 4.4+/-0.5 and 5.4+/-0.4 hours after i.v. and i.m. route respectively. The relatively long elimination half-life in SBF with a mean residence time of about 8 hours allows the use of cefodizime once-a-day for the treatment of infections due to sensitive pathogens.

Adult↗
PubMed2000

Cytotoxicity, DNA damage, and cell cycle perturbations induced by two representative gold(III) complexes in human leukemic cells with different cisplatin sensitivity.

The gold(III) complexes [Au(phen)Cl2]Cl and [Au(dien)Cl]Cl2 were recently shown to exert important cytotoxic effects in vitro on human tumor cell lines. To elucidate the biochemical mechanisms leading to cell death, the effects produced by these gold(III) complexes on the leukemic CCRF-CEM cell line--either sensitive (CCRF-CEM) or resistant to cisplatin (CCRF-CEM/CDDP)--were analyzed in detail by various techniques. For comparison purposes the effects produced by equitoxic concentrations of cisplatin were also analyzed. First, the dependence of the IC50 values of either complex on the incubation time was investigated. Cytotoxicity experiments confirmed that both gold(III) compounds retain their efficacy against the cisplatin-resistant line: only minimal cross-resistance with cisplatin was detected. Notably, [Au(phen)Cl2]Cl is more cytotoxic than [Au(dien)Cl]Cl2, with IC50 values of 7.4 and 6.0 M at 24 and 72 h, respectively, on the resistant line. Results of the COMET assay point out that both gold(III) complexes directly damage nuclear DNA. Remarkably, DNA damage inferred by either gold(III) complex in the two cell lines is larger than that produced by equitoxic cisplatin concentrations. Finally, the effects that either gold(III) complex produces on the cell cycle were investigated by flow cytometry. It was found that both complexes cause only moderate and transient cell cycle perturbations. Larger cell cycle perturbations are induced by equitoxic concentrations of cisplatin. The implications of the present results for the mechanism of action of cytotoxic gold(III) complexes are discussed.

Antineoplastic Agents↗
PubMed1999

New criteria for selecting the proper antimicrobial chemotherapy for severe sepsis and septic shock.

The mortality rate resulting from severe bacterial sepsis, particularly that associated with shock, still approaches 50% in spite of appropriate antimicrobial therapy and optimum supportive care. Bacterial endotoxins that are part of the cell wall are one of the cofactors in the pathogenesis of sepsis and septic shock and are often induced by antimicrobial chemotherapy even if it is administered rationally. Not all antimicrobial agents are equally capable of inducing septic shock; this is dependant on their mechanism of action rather than on the causative pathogen species. The quantity of endotoxin released depends on the drug dose and whether filaments or spheroplast formation predominates. Some antibiotics such as carbapenems, ceftriaxone, cefepime, glycopeptides, aminoglycosides and quinolones do not have the propensity to provoke septic shock because their rapid bactericidal activity induces mainly spheroplast or fragile spheroplast-like bacterial forms.

Anti-Bacterial Agents↗