In vitro inactivation of gentamicin, tobramycin, and netilmicin by carbenicillin, azlocillin, or mezlocillin

The in vitro inactivation of gentamicin, tobramycin, and netilmicin, when combined with carbenicillin, azlocillin, and mezlocillin, was studied. Plasma samples containing the aminoglycosides at a concentration of 5-8 micrograms/ml in combination with the penicillins in concentrations of 500, 250, and 50 micrograms/ml were incubated at room temperature and 37 degrees C for 0.3, 1, 3, 6, and 9 days. The aminoglycoside concentration was determined by radioimmunoassay or enzyme immunoassay. The extent of inactivation was dependent on penicillin concentration, contact time, and temperature. Penicillin concentrations of 500 micrograms/ml caused the greatest loss of aminoglycoside, while little loss occurred at the 50-micrograms/ml penicillin level. Carbenicillin, in concentrations of 250 and 500 micrograms/ml, inactivated all three aminoglycosides to a greater extent than either azlocillin or mezlocillin. The initial rate of decline in aminoglycoside concentration was greater at 37 degrees C than at room temperature. The new acylureidopenicillins, azlocillin and mezlocillin, inactivate the aminoglycosides studied, in a similar manner to that previously described for carbenicillin.     

In vitro activity of modern penicillins and cephalosporins against enterococci

The in vitro activity of nine penicillin and cephalosporin antibiotics against enterococci was compared by MIC determination and killing curve experiments. To inhibit 90% of the 143 clinical isolates tested the following drug concentrations were required: mezlocillin, 1--2 micrograms/ml; azlocillin, 2 micrograms/ml; piperacillin, 4 micrograms/ml; cefazedone, 16 micrograms/ml; cefazolin and cefoperazone, 32 micrograms/ml; ticarcillin, 64 micrograms/ml. Cefotaxime and lamoxactam proved to be almost ineffective at 128 micrograms/ml which was the highest concentration tested. In killing curve experiments a reduction of viable cell count by 2--3 logs was achieved with all antibiotics except cefotaxime and lamoxactam. In general, the acylureido-penicillins exhibited a better bactericidal activity than the cephalosporins.     

Clinical studies on the biliary excretion of mezlocillin, especially in cases with liver dysfunction

To investigate efficacy of mezlocillin (MZPC) in the treatment of biliary tract infection, the time course concentrations of MZPC in the bile of patients with, in particular, liver dysfunction were measured. MZPC concentrations in the bile decreased with the increase in the severity of liver dysfunction. However, the bile concentration was maintained more than 50 micrograms/ml even in cases of severe cholangitis with obstructive jaundice. These results indicate that MZPC is an useful antibiotic for the treatment of biliary tract infection.     

Activity of 4′-0-tetrahydropyranyladriamycin hydrochloride (THP-ADM) in a human tumor cloning system

4'-0-tetrahydropyranyladriamycin hydrochloride (THP-ADM) is a new anthracycline derivative. The antitumor activity of THP-ADM was tested on 51 human tumor samples representing ten different tumor types in in vitro colony assay method. Tested tumors were: 26 cases of ovarian cancer, 8 cases of breast cancer, 6 cases of colorectal cancer, 3 cases of endometrial cancer, 2 cases each with gastric cancer and sarcoma, and another 4 cases. An in vitro colony assay was done in soft agar as described by Hamburger & Salmon. The criteria for in vitro sensitivity was defined as a 70 percent or greater reduction in the number of colonies after a 1-h exposure to drugs. The selected concentrations of THP-ADM for assay were 0.05, 0.5, and 1.0 micrograms/ml. The sensitivity rates for THP-ADM in each dose were: 0.05 micrograms/ml (7/19, 37%), 0.5 micrograms/ml (10/51, 20%), and 1.0 micrograms/ml (12/19, 63%). In vitro sensitivity of adriamycin (0.04 micrograms/ml) was simultaneously tested in 49 cancer patients. Five out of 25 ovarian cancer patients (20%) showed responses to adriamycin and an overall response rate was 12% (6/49). These data indicate that THP-ADM has an antitumor activity against various cancers and it is comparable to that of adriamycin.     

鞘氨醇激酶1抑制剂和5-FU联合应用对体外胃癌细胞增殖与凋亡的影响

目的观察鞘氨醇激酶1(SphK1)抑制剂二甲基鞘氨醇(DMS)与化疗药物5-氟尿嘧啶(5-FU)联合应用对体外胃癌细胞SGC7901增殖与凋亡的影响。方法体外培养人胃癌细胞株SGC7901,分别单用不同浓度5-FU(1、5、25μg/ml)或5-FU与DMS(1μmol/L)联合应用。MTT比色法检测各组细胞生长抑制率,光镜下观察细胞形态变化,流式细胞术检测各组细胞凋亡率。通过SAS软件进行反应曲面分析,分析两药之间的关系。结果不同浓度的5-FU单用组及联用DMS组的抑制率差异有统计学意义(P<0.05),联用组抑制率均高于单用组,两者具有协同作用。单用DMS组及5-FU组的胃癌细胞凋亡率较空白对照组明显增高,联用组凋亡率较单用组明显增加(P<0.05)。结论 DMS可抑制SGC7901细胞的增殖;DMS和5-FU联用显示了较好的协同作用,提示抑制SphK1活性能够提高胃癌细胞对于化疗药物的敏感性。     

Simultaneous determination of tegafur and 5-fluorouracil in serum by GLC using nitrogen-sensitive detection

A sensitive assay of both tegafur (I) and 5-fluorouracil (5-FU) using GLC with a nitrogen-phosphorus-sensitive detector is described. The drugs were extracted from rabbit serum with ethyl acetate and methylated with diazomethane. Linearity was obtained over the concentration ranges of 3.13-200 micrograms/ml for I and 0.0313-2 micrograms/ml and 10-50 ng/ml for 5-FU. The detection limits of I and 5-FU in serum were 50 and 8 ng/ml, respectively. The serum concentrations of the drugs determined by the present method closely agreed with those obtained by spectrophotometry for I and microbial assay for 5-FU.     

The mechanism of action of myxovalargin A, a peptide antibiotic from Myxococcus fulvus

Myxovalargin A has two modes of action. At low concentrations (below 1 microgram/ml) it inhibits bacterial protein synthesis specifically and instantaneously. In vitro experiments suggest that it interferes with the binding of aminoacyl tRNA to the A site of the ribosome. At higher concentrations (above 5 micrograms/ml), or upon prolonged incubation, the antibiotic damages cell membranes. This leads to secondary effects, like decreased O2 consumption or instant break down of RNA synthesis, and may be the reason for the irreversibility of the antibiotic action. The membrane effect is not restricted to prokaryotes and may explain the high toxicity of the compound for higher organisms.     

In vitro teratogenicity of acetylsalicylic acid on rat embryos: studies with various culture conditions

Rat embryos taken at day 9.5 of gestation were exposed in vitro to acetylsalicylic acid (aspirin) using various culture conditions. It was observed that embryos were sensitive to aspirin emulsified in olive oil at concentrations greater than or equal to 150 micrograms/ml. Between 43% and 66% of the embryos exhibited multiple malformations depending on the culture medium, 100% homologous rat serum or Waymouth medium supplemented with 50% rat serum, respectively. At concentrations greater than or equal to 400 micrograms/ml aspirin induced further toxic effects on embryo growth and differentiation. When gelatin was used as the drug-delivery system, aspirin at concentrations of greater than or equal to 150 micrograms/ml induced some malformations (mainly irregular somite shapes) in 57% of the embryos cultured in Waymouth medium, but in only 13% of the embryos grown in 100% serum. At concentrations which were greater than or equal to 400 micrograms/ml aspirin induced dysmorphogenic effects in all embryos, without any concomittant toxicity.     

Stability of penicillins in total parenteral nutrient solution

The stability of ticarcillin, mezlocillin, and piperacillin in total parenteral nutrient (TPN) solutions at concentrations commonly used in adults was determined. Each antibiotic was added separately to three different amino acids-dextrose TPN solutions in two concentrations: 10 and 20 mg/mL. Amino acids concentration ranged from 25 g/L to 50 g/L. Dextrose concentration ranged from 100 g/L to 350 g/L. Solutions were assayed for antibiotic concentration immediately after mixing (time 0) and at 4, 8, 24, and 48 hours by high-performance liquid chromatography. The effect of the added penicillins on the stability of amino acids and other TPN additives was not investigated. Mezlocillin and piperacillin 10 and 20 mg/mL exhibited stability in TPN solution at 24 hours. Ticarcillin was stable for 24 hours at a concentration of 10 mg/mL, but at 20 mg/mL it was unstable at all times tested. The three antibiotics demonstrated the same characteristic stability in all three TPN solutions, suggesting that the concentrations of dextrose and amino acids did not affect stability. Ticarcillin, mezlocillin, and piperacillin are stable for 24 hours in the TPN solutions studied.     

Efficacy of sequential treatment of HCT116 colon cancer monolayers and xenografts with docetaxel, flavopiridol, and 5-fluorouracil

AIM: Clinical treatment of solid tumors with docetaxel, flavopiridol, or 5-fluorouracil (5-FU) often encounters undesirable side effects and drug resistance. This study aims to evaluate the potential role of combination therapy with docetaxel, flavopiridol, or 5-FU in modulating chemosensitivity and better understand how they might be used clinically. METHODS: HCT116 colon cancer cells were treated with docetaxel, flavopiridol, and 5-FU in several different administrative schedules in vitro, either sequentially or simultaneously. Cell survival was measured by MTT assay. The activity of caspase-3 was determined by caspase-3 assays and the soft agar colony assay was used to test the colony formation of HCT116 cells in soft agar. We also established xenograft models to extend in vitro observations to an in vivo system. RESULTS: The maximum cytotoxicity was found when human colon cancer HCT116 cells were treated with docetaxel for 1 h followed by flavopiridol for 24 h and 5-FU for another 24 h. This sequential combination therapy not only inhibits tumor cell growth more strongly compared to other combination therapies but also significantly reduces colony formation in soft agar and augments apoptosis of HCT116 cells. Sequencing of docetaxel followed 1 h later by flavopiridol, followed 24 h later by 5-FU in xenograft models, also resulted in delayed tumor growth and higher survival rate. CONCLUSION: These results highlight the importance of an administrative schedule when combining docetaxel with flavopiridol and 5-FU, providing a rationale explanation for its development in clinical trials.     

Derivatives of amphotericin inhibit infection with human immunodeficiency virus in vitro by different modes of action

Three water-soluble derivatives of amphotericin B were tested for inhibition of HIV infection in vitro. The compounds amphotericin B methyl ester (AME) and N-(N'-(2-(4'-methylmorpholinio)ethyl)N"-cyclohexyl guanyl) amphotericin B methyl ester (MCG) inhibited HIV infection by 50% at 1 microgram/ml; N-(N'-(3-dimethylaminopropyl)N"-ethyl guanyl) amphotericin B (DAPEG) did so at 5-11 micrograms/ml. While the virus-inhibitory effect of AME was due to an interaction with target lymphocytes, the effect of MCG was due to a direct anti-viral action. AME increased the potential of infected cells to fuse with uninfected cells, but MCG had no significant effect on cell fusion. All compounds had a lower cellular toxicity than amphotericin B and were not toxic at concentrations below 20 micrograms/ml.     

Modulation of 5-fluorouracil metabolism by thymidine. In vivo and in vitro studies on RNA-directed effects in rat liver and hepatoma

The effects of thymidine (TdR) co-administration on the cytotoxicity and incorporation of 5-fluorouracil (5-FU) into RNA of various tissues was studied in rats bearing an ascites hepatoma (AH 130). The role of pyrimidine degradation in determining the modulating effects of TdR on the formation of FU-RNA was studied in hepatocytes and AH 130 cells in vitro. TdR (500 mg/kg) potentiated the antitumour effect of 5-FU (150 mg/kg) and also increased host toxicity as judged by changes in body weight. TdR given alone did not significantly affect tumour growth and body weight gain. Examination of the effect of TdR on the incorporation of 5-FU into RNA revealed a differential modulation of RNA-directed toxicity in different tissues. Incorporation of 5-FU into RNA in tumour and bone marrow was increased 2- and 4-fold, respectively. In spleen and kidney the incorporation increased by approximately 50%, but the values did not reach statistical significance. In contrast, the incorporation into RNA of liver and intestinal mucosa was decreased to ca 35% of the control. TdR at concentrations of 40 microM-40 mM progressively inhibited the degradation of 5-FU and decreased the incorporation of 5-FU into RNA of hepatocytes in vitro. In AH 130 cells in vitro TdR did not significantly influence the metabolism of 5-FU and the incorporation into RNA. These results demonstrate that the enhanced incorporation of 5-FU into tumour RNA in vivo after pretreatment with TdR is related not to local effects on the tumour cells but rather to an increased bioavailability of the drug. Although co-administration of TdR did not selectively enhance the antitumour effect of 5-FU, a differential toxicity in host tissues was indicated by the modulated incorporation of 5-FU into RNA.     

Potassium oxonate modulation of 5-fluorouracil-induced myelotoxicity in murine and human colony forming assays of hematopoietic precursor cells

Potassium oxonate (Oxo) is one of three components of S-1, an anticancer drug developed to improve the selective toxicity of 5-fluorouracil (5-FU). Oxo has been shown to reduce gastrointestinal toxicity. In this study, using murine and human granulocyte/macrophage colony forming (mCFU-GM, hCFU-GM) assays, we investigated whether Oxo can reduce 5-FU-induced myelotoxicity. The respective concentrations of 5-FU for 50% reduction (IC(50)) in mCFU-GM and hCFU-GM assays were 1.1 and 0.76 microM. The concentration-response curve was substantially steeper in the mCFU-GM assay than in the hCFU-GM assay. In the mCFU-GM assay, Oxo prevented growth suppression by 1 and 2 microM 5-FU, and at greater than 1 microM, it prevented suppression by 1 microM 5-FU almost completely. In the hCFU-GM assay, in contrast, Oxo prevented 5-FU suppression only slightly, and without a dose-response relationship. The difference between the mCFU-GM and hCFU-GM results may have stemmed from the spontaneous decomposition of Oxo during the longer culture period and Oxo's toxicity for human cells. Considering the human pharmacokinetic data, we concluded that Oxo has the potential to reduce 5-FU-induced myelotoxicity in human.     

雷公藤红素联合5-氟尿嘧啶在人结肠癌细胞中的相互作用

目的体外观察雷公藤红素与5-氟尿嘧啶（5-FU）联用在人结肠癌HCT-116细胞增殖中的相互作用。方法采用MTT法观察不同浓度雷公藤红素及5-FU单独或联合应用对结肠癌细胞的生长抑制作用,并利用中效原理判断联合用药的效果。结果雷公藤红素和5-FU单独应用时,随药物浓度增加对HCT-116细胞的抑制作用也增加,中效浓度分别为3.533μmol/L,9.254μmol/L,两药联用时在大部分效应范围（0〈fa〈83％）表现协同作用（CI〈1），中效浓度为6．433μmol／L．其中雷公藤红素0．099μmol／L，5-FU6．33μmol／L。两药合用给药时间及次序不同时不同时，合用效应无明显差异。结论上述两种药物联合应用时具有较好的协同效应，且药物效应与给药顺序无关。     

Effects of antirheumatics on the glycosaminoglycan distribution pattern of fetal tibia cultured in vitro

The glycosaminoglycan (GAG) distribution pattern of murine fetal tibiae cultured for 6 days in vitro was determined and the effects of drugs on the growth of the tibia explants in vitro, on their total GAG content and on their GAG distribution pattern were studied. The explants contained chondroitin-4-sulfate and chondroitin-6-sulfate in a relation of about 4:1; hyaluronic acid was not detected. During the incubation period of 6 days in vitro a mean increase in size of 47% and of the total GAG content of about 80-90% was observed; the GAG distribution pattern was practically unchanged. Incubation of the explants in a medium without ascorbic acid by contrast to a medium containing ascorbic acid (5 and 50 micrograms/ml) lead to a reduction of growth and total GAG content. The nonsteroidal antiphlogistic drugs phenylbutazone (20 and 200 micrograms/ml), ibuprofen (25 and 200 micrograms/ml) and alclofenac (25 and 400 micrograms/ml) effected a concentration dependent decrease of the growth and of the GAG content of the explants mainly due to a reduction of chondroitin-4-sulfate. Prednisolone (10 micrograms/ml) caused a significant increase of the GAG content of the explants leaving their GAG distribution pattern nearly unchanged. Aurothioglucose (400 micrograms/ml) induced a reduction of the growth and of the GAG content of the explants without altering the GAG distribution. Under low concentrations of Na-pentosanpolysulfate (5 micrograms/ml) an increase in growth and in the GAG content by a nearly unaltered GAG distribution pattern was observed, high concentrations (200 micrograms/ml), however, caused a reduction of growth and of the GAG content.     

A new antibiotic, okicenone. I. Taxonomy, fermentation, isolation and biological characteristics

A new antibiotic, okicenone was isolated from the culture broth of Streptomyces sp. KO-3599. The antibiotic possesses cytocidal activity against mammalian tumor cells in vitro at concentrations of 0.53-11.0 micrograms/ml whereas the antibiotic showed no antimicrobial activities against Gram-positive and Gram-negative bacteria, fungi or yeast at a concentration of 1,000 micrograms/ml.     

Dipyridamole combination chemotherapy can be used safely in treating gastric cancer patients

The feasibility of a combined chemotherapy using dipyridamole (DP) with adriamycin (ADM) and 5-fluorouracil (5-FU) was investigated. First, the chemosensitivity of gastric cancer tissues was determined by the succinate dehydrogenase inhibition test, which showed sensitivity to ADM and 5-FU is increased by DP. Next, a clinical trial of combined therapy of DP, ADM and 5-FU, as a post-operative adjuvant chemotherapy for gastric cancer patients, was performed. DP (50 mg) was given as a 1-h i.v. infusion, and ADM (20 mg) was given as a single i.v. injection. This treatment was started on post-operative day 10, and was repeated every 2 weeks. Simultaneously with these treatments, DP (300 mg) and 5-FU (150 mg) were administered post-operatively daily. A total of 63 courses of therapy in nine patients were performed. The adverse effects related to the DP infusion were flushing, headache, nausea and upper abdominal discomfort, all of a low grade. DP did not appear to alter the toxicity of ADM and 5-FU, and no severe adverse effect was noted for this combination therapy. The pharmacokinetics of DP were also investigated in five patients. The mean plasma concentration of DP increased 4.41 micrograms/ml and remained above 0.25 microgram/ml for over 6 h. This combination chemotherapy appears to be safe and may be useful clinically in treating cancer.     

In vitro and in vivo cytotoxicity of possible uracil metabolites of methylxanthines

The present study was designed to elucidate the cytotoxic potential of 8 possible substituted uracilic metabolites of methylxanthines. 5-Fluorouracil (5-FU) was used as a reference uracil analogue with cytotoxic activity. Substituted uracil derivatives examined in this study did not affect the proliferative capacity of PHA-stimulated rat lymphocytes, murine L1210 leukaemia and rat chondrocytes. Caffeine had some growth inhibitory activity of extremely high concentrations (greater than 100 micrograms/ml). In vivo administration of 6-amino-5[N-methyl-formylamino]1,3-dimethyluracil (1,3,7-TAU) and 6-amino-5[N-acetylamino]3-methyluracil (7-A3-MAU) caused a transient short-lived reduction of L1210 tumour cell numbers. These observations do not appear to support the hypothesis that substituted uracils are involved in the toxicity of high doses of caffeine in rats.     

In vitro activity of aztreonam, cefuroxime and ceftazidime against gram-negative rods isolated from hospital patients with urinary tract infection

The in vitro activity of aztreonam, cefuroxime and ceftazidime was determined against 2,372 Gram-negative rods (including Pseudomonas spp.) isolated from hospital patients with urinary tract infections during 1985. Minimum inhibitory concentrations (MICs) were determined using an agar incorporation technique in Mueller-Hinton agar. The inoculum used was approximately 10(5) colony forming units (cfu) contained in 10 microliter Mueller-Hinton broth, which was applied to the surface of the agar plates using a multipoint inoculator. Following inoculation plates were incubated aerobically at 37 degrees C for 18 h. The MIC of each antimicrobial for each organism examined was determined as the lowest concentration of the antimicrobial which completely inhibited growth of the inoculum. The minimum concentration required to inhibit the growth of 90% (MIC90) of the bacterial isolates in each genus or species examined was also determined. In general the antibacterial spectrum of aztreonam was comparable to that of ceftazidime and superior to that of cefuroxime. Against Escherichia coli, which accounted for 72% of the isolates examined, aztreonam (MIC90 less than or equal to 0.25 microgram/ml) was slightly more active than ceftazidime (MIC90 0.5 microgram/ml) and considerably more active than cefuroxime (MIC90 8 micrograms/ml). Aztreonam was active against Pseudomonas spp. (MIC90 16 micrograms/ml), although somewhat less so than ceftazidime (MIC90 4 micrograms/ml). Cefuroxime showed low activity against this genus (MIC90 greater than 128 micrograms/ml).     

Severe 5-fluorouracil toxicity associated with a marked alteration of pharmacokinetics of 5-fluorouracil and its catabolite 5-fluoro-5,6-dihydrouracil: a case report

OBJECTIVE: To describe the altered pharmacokinetics of 5-fluorouracil (5-FU) and its major catabolite 5-fluoro-5,6-dihydrouracil (5-FDHU) in a 52-year-old woman affected by a severe 5-FU toxicity. METHODS: Toxicities were rated according to World Health Organization. 5-FU and 5-FDHU plasma concentrations and dihydropyrimidine dehydrogenase (DPD) activity of peripheral blood mononuclear cells (PBMC) were measured by HPLC analysis. RESULTS: After a single cycle of 5-FU therapy the patient developed grade 4 diarrhea and stomatitis, grade 3 vomiting, neutropenia, and dermatitis. Compared to a control population, 5-FU AUC, elimination half-life, and C(max) were markedly increased (24.75 vs. 9.25 +/- 0.63 h microg/ml, >5 vs. 0.36 +/- 0.05 h, and 58.54 vs. 37.2 +/- 4.03 microg/ml, respectively) whereas systemic clearance was decreased (12 vs. 51.29 +/- 2.97 l/h/m2); also 5-FDHU AUC (3.3 vs. 12.35 +/- 0.7 h microg/ml) and C(max) (3.4 vs. 4.56 +/- 0.15 microg/ml), which was reached with delay, were reduced. Surprisingly, the PBMC DPD activity (110.8 pmol/min/mg protein) and urinary uracil (68.32 micromol/g urinary creatinine) were within normal range. CONCLUSIONS: Our results show the altered 5-FU and 5-FDHU pharmacokinetics in a severe 5-FU toxicity case due to an impairment of the hepatic DPD activity and suggest the necessity of a pharmacological evaluation of 5-FU treated patients.